Annual Conference 2007, Royal Geographical Society, London Session key: CCRG-session 2
29-31 August, 2007 Paper-2
GLOBAL WARMING AND CHANGING LAND USE PATTERNS IN BIHAR PLAINS, INDIA
Nupur Bose1, A.K.Ghosh2. K.R.P.Singh3, Rajiv K.Sinha4
1Department of Geography, A.N.College, Patna, India
2 Department of Environment and Water Management, A.N.College, Patna
3 remote sensing Application Centre, Patna, India
4 Department of Environmental Engineering, Griffith university, Brisbane, Australia
ABSTRACT-
The densely populated fluvial plain of Bihar is sustained by its agro-based economy. Its land use patterns are largely determined by its abundant fresh water resources augmented by monsoon rainfall. This study was aimed to find the quantum of changes in land use in the region, and identifying the visible, recorded physical causes for these changes. The methodology was based on image processing techniques of IRS-WiFS Sensor satellite imageries of March 1984 and December 2004. Comparative analysis of areas under major land use types was done. References of topographical sheets were obtained to corroborate the findings with ground realities. There was significant reduction in areas under crop cultivation and wetlands, while forest and plantation cover increased by almost 20%. Fallow lands registered a sharp increase. Sandy stretches, bereft of any significant plant cover, also had larger areal spread. The study revealed concomitant reductions in spatio-temporal surface water configurations and sharp recession of Himalayan ice cover within the time span of eighteen years. Though neotectonics have been attributed to changes in the river flow systems, the stark evidence of global warming in the form of gradual shrinking of the perennial sources of water of the region's drainage system cannot be ignored.
INTRODUCTION-
In Bihar, rapid changes in surface water bodies and channel flows have been noted on two satellite imageries obtained in the spring season, covering a time span of last two decades. There are contradictory trends in eastern and western parts of the state - the former showing expansion of surface water and the latter revealing rapid shrinkage of the same. Corresponding changes in seasonal land use indicate the increasing primacy of hitherto unimportant factors of the changing Man-Environment relationship in the state.
The nature of land use in Bihar has been traditionally dependent upon varying conditions of relief, rainfall, soil fertility, water availability, population density patterns, transport, communication, and access to markets. Generally, although over 80% of the total land is devoted to primary activities, inter-regional variations exist
PHYSICAL ASPECTS AFFECTING LANDUSE -
The reorganized State of Bihar is located within Mid Gangetic valley. Bihar covers an area of 94,163 sq. km. and possesses a rich network of surface drainage lines, both from the northern Himalayan ranges and southern plateaus. Basically a part of the mid-Ganga Plains, most of the study area was formed during the late Palaeogene-Neogene times, and is related to the upheaval of the Himalayas vis a vis flexural down warp of the Indian lithosphere under the supracrustal load of the Himalayas [Wadia, 1961]1. Bihar Plains lie on a highly active seismic belt, seismicity being greater towards the north. The western part of the study area is geologically proved to be uplifting in the upstream area, with the result that the general slope is tilting to the south-east2. This is gradually contributing to the draining out of the tectonic sags and surface depressions in the west towards east and south-east.
The hydro-geological framework of the region gets reflected in the numerous channel flows, the wetlands and other fluvial features. The plains are also subject to frequent channel avulsions, flooding, and resultant sedimentation3. These events have influenced the patterns of wetlands, most of which originate from the meandering streams. The rivers appear to be aggrading, thereby increasing the annual overspills, more so in the east4. The surface is composed of calcareous alluvium in north-west, non-calcareous soil in the north-east, and forest and hill soils in the plateau rim of the south5.
Climatic variations, resultant rainfall distribution and water availability also impact Bihar’s land use. In North Bihar, annual inundation is common, while drought-like conditions prevail in the south. The Himalayan ice caps and glaciers feed the innumerable south flowing streams, and along wit the monsoon rains, contribute to high fertility of Bihar Plains. Supply of water is also affected by hydrological changes, where determinations of channel conditions due to excessive aggradations, itself the result of an increase in the quantities of sediment carried by the major tributaries of the Ganga have occurred6. Hence, any change in the factors affecting surface water availability impacts the pattern of land use. This study refers to the dry period of December-March, when demand for water availability is highest.
SOCIO-ECONOMIC ASPECTS AFFECTING LANDUSE -
The economy of the reorganized Bihar is underdeveloped and heavily dependent on agriculture. Bihar has the lowest per capita income in India - below Rs. 5000/- as against the national per capita income of Rs. 10,254/- [1993-1994]. Bihar is also densely populated. As per 2001 census, there were 82,998,509 persons, which is about 8.08% of the population of the country, with a density of 881 persons/sq.km7.
The pressure of population have forced deforestation and decrement of the area under orchards and pasture Hence, the land use pattern has a long chronology of being dominated by agricultural production. Traditional agricultural practices are based on near-total dependence on monsoons, with very little land allocated to other activities. Agriculture is the main stay of the rural people of the state, which provides direct and indirect employment to around 77.35% of the total work force of the state and contributes 87% of the Net State Domestic Product. Agriculture, combined with Animal Husbandry, are characterised by low productivity due to traditional practices, inadequate capital formation, low investment, inadequate irrigation According to the Agricultural census, the total number of operational holdings was 75,77,251, 79% of which were of less than 2 acres.
CROPPING PATTERN IN BIHAR [1980s]
Source: Bihar through figures, 1986, Govt. of Bihar, India
Cropping Pattern:
Paddy is the principal food crop of the state and accounts for about 46.66% of the total gross cropped area, followed by wheat (27.93%) and pulses (9.13%). Similarly, the area under cash crops and oilseeds account for 5.89% and 1.88% respectively.
The physical bases of location, configuration, drainage, soil, sub-surface strata, temperature and precipitation with access to water supplies, define the limits of the biotic potentialities of the land. The human bases including the extent of occupancy, population density, social and economic institutions, along with accessibility to markets, transport and communication, control the extent to which the resources of the land are utilized8.
Land Use Pattern:
Bihar has an agro-based economy. As per records, land use pattern in Bihar stresses on primary activities with 78.97 lakh hectares out of total geographical area of 93.60 lakh hectares in 1997-98, under crops. 22.33 lakh hectares were given to multiple cropping, and net sown area was 56.6 lakh hectares. Only 6.22 lakh hectares of forest cover remained in the decade of the nineties. Bihar Plains are almost immune to this category. In the decade of the eighties, they constituted 6.58% of the land cover in Bihar. Altered natural vegetation comprising of dry deciduous forests now survive in areas having less than 1200 mm. rain in the rims of the Highlands in south Bihar. High rainfall of over 1500 mm.permit the growth of moist deciduous forests in the Dun and Someshwar ranges in the north-west and Saharsa and Purnea Districts in the north-east. The area under miscellaneous crops, groves and pastures totalled to 2.53 lakh hectares9. Fallow lands and barren segments are found in the drier parts of the state. The nature of land use in Bihar is dependent upon varying conditions of rainfall, soil fertility, water availability, population density, transport and access to markets. Hence, while eastern Bihar is usually intensively cultivated, the water bodies and swampy conditions inhibit year-round cultivation in the northern part
LAND USE IN BIHAR [1997-98]
PURPOSE OF STUDY
The satellite imageries revealed that the changes in surface land use patterns have taken place too rapidly to assign the cause of these changes solely to neotectonism. The spatio-temporal impact of global warming on economic activities, particularly on agriculture, needed to be assessed. The aim of this study was, therefore, to consider the extent of changes in the areal spread of major land use categories in Bihar in the dry seasons [December –March] in 1984 and 2004, and to seek explanation of these changes especially in the context of evidences of global warming.
METHODOLOGY
Remote sensing techniques have been used to observe and analyze the changes in the land use of Bihar Plains, its geographical location being between 21058’10” N and 27031’15”N latitudes, between 82019’50”E to 89017’40”E longitudes. Two satellite imageries of IRS-WiFS Sensor [Indian Remote Sensing – Wide field Sensor] of March 1984 and December 2004 were studied. The image processing was done on ERDAS-Imagine Version 8.3. FCC was classified, and the classified images were recoded to generate the desired results. The image resolution is of 80 meters. Changes in pixels were calculated. Upon superposition of the physical map of Bihar over the images, comparative picture of the changing trends in the state was highlighted, and subject to analyses and explanations. Limited GT ( Ground Truth ) data were collected for the image processing
SOI [Survey of India Topographical sheets were referred to corroborate the findings. State Boundary was digitized as Vector to know the extent of the study area. The vector was changed in the form of raster to get the statistical value of the spatial extent of crop cover.
Field study of Kabar Tal wetland [ a proposed RAMSAR Site] in Begusarai District, was also undertaken to verify shrinkage of wetlands particularly in north Bihar10.
Interviews with local population, for perception of changes in normal temperature and rainfall variations, land use and surface water availability, were conducted.
The interpretation of the land use changes was based on the observation of the images of two years, obtained in March 1984 and December 2004. Pixel calculations were used to identify important land use categories, which have direct influence on the state’s economy, and may not agree with the land use data collected manually by authorities. These are –
1. Wetlands.
2. Forests – this included the area under plantation.
3. Cropped land
4. Fallow land – These are marginal lands whose prospects for use increase with adequate availability of water and other agricultural inputs like better seeds and fertilizers
5. Area under Sand deposits and cloud cover
6. Unclassified land – That which has not been classified, either because the scientists are not aware what is lying in those areas, or because of the fact that the specific area falls beyond the purview of this study.
FINDINGS –
Although both March and December are dry months, surface water availability and sown area coverage are generally more in December as this follows the post monsoon period. By March, winter crops near harvest time in the plains, thereby covering much of the agricultural lands.
This study reveals a changed scenario, in which rivers, wetlands, agricultural land and land under forests exhibit a dynamism that is a harbinger of changes in agricultural trends, and in turn, the state’s economy. Reduction in pixels representing water bodies between the 1984 and 2004 images indicates decrease in areas of water bodies in the western part of the state. Massive sedimentation in the December 2004 image is revealed in the Ghagra-Gandak Interfluve in the north western segment, so much so that the channel flow of the lower Gandak river is almost obliterated. Declining wetlands were noted even in the piedmont north and the adjacent marshy terrain. However, towards the north-east, surface water increased spatially. The Kosi fan and its downstream section revealed an almost 8% increase in surface water area, this being due to the heavy silt load of the river and resultant spillage by the river. A historically flood-prone area, northern Bihar’s topography is characterized by abandoned meanders and channel avulsions. But a comparative study reveals that surface water availability in the dry periods of the two years declined by around 40% in west Bihar and increase by approximately 10% in the east.10 , and declined by -43.40% for the state as a whole. Kabar Tal, a bird Sanctuary in central-east Bihar, covered 6786 hectares in March 1984, but 20 years later, it shrunk to 6043 hectares, the shrinkage being on its western flanks. To the east of these clusters of wetlands, an increase in surface water configuration was noted.
The area under forests is officially stated to be decreasing. However, in this study, interpretation of the satellite imagery included all types of green cover, forests and plantations. The continuous vegetation belt along the northern rim of the platean in south Bihar stood almost obliterated in the second image. Only Munger hill forests, near the southern bank of the Ganga river, was least affected. There was a simultaneous accumulation of swampy tracts and water bodies in the nearby areas that could have attributed to the continuity of this forest zone.
The enhanced figure of forested land, therefore, bears testimony to the rising importance of plantation farming which itself indicates a subtle shift from cereal farming to commercial cropping activity. Since the cropping pattern has historically been dominated by paddy, this shift may be regarded as the farmer’s adaptation to the changing environment of decreasing water resources.
The 1984 image reveals a dominance of cropped area over the Bihar Plains, except in the south-east where most of the flat surface has been left fallow in the dry month of March. Of the total agricultural land, 59.27% was under cultivation. The latter image revealed reduction in pixels in this category of land use, the percentage of agricultural land now being reduced to 54.16%. Also a marginal decrease in the combined categories of agricultural land [cropped land and fallow land] by 80.05 hectares was noted. Significant increase in area under fallow land by approximately 2303 hectares [a 12.35% increase] in the second image of December is suggestive of the fact that changing surface water availability influenced area under crops.
Of greater importance and relevance to changing land use structure was the land under sand. The role of cloud cover becomes minimized if the period of the images studied, is considered. Sand deposits spread by over 40% from the 1984 base year, and included sedimentation of fertile tracts, particularly in north Bihar. Unclassified land increased in cover by 338.6 hectares, registering a 64% expansion beyond its 1984 area.
CHANGES IN MAJOR LAND USE CATEGORIES IN BIHAR
[Based on March 1984 & December 2004 remote sensing images]
Land use types
1984 March
[Fig. in Hectares]
2004 December
[Fig. in Hectares]
Change
[in %]
Wetlands
4023.91
2409.86
- 40.11
Forests [includes plantations]
4812.63
5773.54
19.96
Cropped Area
27148.52
24764.96
- 8.78
Fallow
18653.12
20956.63
12.35
Sand [includes cloud cover/haze]
978.53
1373.12
40.32
Unclassified land
521.52
860.12
64.93
TOTAL
56138.23
56138.23
ANALYSIS OF THE CHANGES –
The study area is an established sedimentation sink and geologically volatile. The high sediment load during the monsoons and frequent spillage in the Ganga and its tributaries normally lead to changes in channel configurations and choking up of wetlands. In north and west Bihar, this is further influenced by neotectonic changes in local slope conditions.. The general slope of the region is tilting to the south-east. But response of each region to sedimentological adjustments and neotectonics is different in magnitude11, this being partly reflected in the land usage of the state. This accounts for sediment and sand deposit increases in the northern-eastern agricultural land between Himalayan foothills and the Ganga.
The above fact was augmented by dramatic changes in the snow cover of the Nepal Himalayas and the Greater Himalayan range that feed the perennial southward-flowing tributaries. InMarch1984, the Himalayan snow belt extended from the vicinity of the upper tract of the Gandak river eastwards in a wider swathe to form the sources of the Sapt Kosi river system. All the mountain streams bore water even in this warm dry month, and the surface depressions were adequately full, thereby supporting a larger area under crop cultivation. Sedimentation was most evident in the upstream area of the Kosi floodplain. The second imagery revealed altered surface drainage, with a visible, considerable disappearance of Himalayan ice cover north and north-west of the fluvial plains. Only the north-eastern ranges feeding the Kosi river network retained their ice cover.
Lesser availability of surface water, therefore, accounted for decline in the seasonal cropping intensity in west and central Bihar and contributed to a larger spread of land left fallow. Conversely, in eastern Bihar, the shrinking wetlands gave way to new arable lands in their outer confines.
CONCLUSION-
Depleting ice covers and glacial recession are having direct impact on the quantum of water and detritus in the perennial Himalayan streams upon which land use patterns have evolved. The Second Bihar State Irrigation Commission, 1994, stated that within Bihar, the river basins already had a shortfall of water availability. This marked depletion does not auger well for the state, for it has already set in motion a series of reactions as exemplified in this study, that are bound to have cataclysmic effects on it’s ecological balance, and in turn, on the economic and social fabric of the state.
Also, the “Interlinking of Rivers” Project of the Govt. of India envisages alteration of the entire nation’s drainage pattern. The Himalayan streams are perennial, snow-fed channels that bring a huge volume of water and load of detritus onto the north Bihar Plains. The right-bank streams drain a huge area south of the Ganga, and overspill their banks during the monsoons. Hence, this flood-prone drainage network, supplemented with adequate monsoon rains ranging between 80-120 cms. per annum, enabled Bihar to meet the textbook definition of “a water-surplus state”. Tragically, this situation is altered in several parts of Bihar today. Dried up riverbeds and truncated flows, along with changes in the area under RABI or winter crop, are the most visible features in the river basins. The emerging environmental constraints would, therefore, come in the way of successful implementation of the interlinking of the rivers in Bihar that fall within the broad framework of this mega-project. Reorganized Bihar has only two precious resources left to cushion its economy – it’s fresh water resources and it’s arable land - which must be conserved for a more balanced regional development.
REFERENCES –
Wadia, D.N. (1961). Geology of India. Macmillan, London.
Geological Survey of India Sp. Publication 31; Bihar-Nepal earthquake, 1993, 14-19, 62-80.
Sinha, R., (1996), Channel avulsion and floodplain structure in the Gandak-Kosi interfan, north Bihar rivers, India. Zeitschrift fur Geomorphologie , 103, 249-268
Ahmad, E. (1971). The Ganga - A Study In River Geography. Geographer, Vol XVIII,; Aligarh Muslim University, India.
Singh, R.P., & Kumar, A. (1970). Monograph of Bihar. Bharati Bhawan, Patna.
Jain, V and Sinha, R. (1996). Monitoring Fluvial Hazards from Space: a Case Study of North Bihar Plains, India. www.GeospatialToday-Articles.htm ; accessed on 20/02/04
8.Census of India –Bihar, 2001
ibid.
Bihar through figures, 2000.
Ghosh, A.K., Bose, N., Singh, K.R.P., & Sinha, R.K. Study of Spatio-Temporal Changes in the Wetlands of North Bihar through Remote Sensing [2004], Proceedings of 12th. International Soil Conservation Organization Conference, Brisbane.
Thursday, December 27, 2007
Population Exposed to Arsenic Contaminated Water in Bihar
Annual Conference 2007, Royal Geographical Society, London Session key: BSG-session 5
29-31 August, 2007 Paper-2
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(2) VULNERABILITY OF POPULATION EXPOSED TO ARSENIC CONTAMINATION IN THE MID GANGA PLAIN OF BIHAR, INDIA
Dr. Ashok Kumar Ghosh, Prof.-in-Charge, Dept. of Environment and Water Management A.N.College, Patna nupur.bose@gmail.com
Dr. Nupur Bose, Lecturer, Dept. of Geography, A.N.College, Patna, India
Dr. Narendra Kumar Roy, Resource Person, Dept. of Environment and Water Management A.N.College, Patna, Bihar
Dr. Ajay Upadhyay, Resource Person, Dept. of Environment and Water Management A.N.College, Patna, India
Mr. Amardeep Singh, Research Scholar, Dept. of Environment and Water Management A.N.College, Patna, India
Mr. Sushant Kumar Singh, Research Scholar, Dept. of Environment and Water Management A.N.College, Patna, India
Arsenic contaminated aquifers, being used for direct and indirect human consumption, have severe health implications among the rural population in the state on Bihar, India. This study covered a 10 km. belt along the Ganga river in the four districts of Bhojpur, Patna, Vaishali and Bhagalpur. The purpose of this research was to obtain the distribution and quantum of human population at risk of arsenic poisoning and population composition characteristics of the arsenic-affected belt. The methodology adopted was based upon self-generated and confirmed primary data on abnormally high arsenic concentration in ground water ranging from above 10 ppb. to 1861 ppb. Percentage of hand pumps testing with more than 10 ppb. arsenic content were calculated. This data was compared with the Census 2001 data to obtain estimates of affected population, while Topographical and Administrative Block Maps of all four districts were referred to for studying the spatial pattern of this population. The result showed that approximately 1,537,426 persons [about 47% of the population] residing in the study belt are at risk. In Bhagalpur study belt, the vulnerability extends to more than 75% of the population. Symptoms of arsenic poisoning are widespread, especially among child population. Appropriate mitigation strategies are yet to be undertaken in this study area.
INTRODUCTION –
Bihar is located entirely in the Ganga drainage basin, the geographical extent being 240 20’N to 270 31’15”N, and 830 19’50” E to 880 17’40”E longitudes. Bihar is the second most densely populated state of India having 82,878,769 persons, 89.53% of which is rural population. The per capita income of this economically backward state is a meagre , and it is largely sustained by its agriculture-driven economy. The physical geography of these plains, characterised by annual inundations and frequent meander changes in the river network, generally force rural inhabitants to relocate their habitation sites, particularly in central and north Bihar. It has also resulted in emergence of new areas of alluvial deposits. The presence of ample surface and ground water sources generally confined the problem of water resource to management of flood situations till the last decade. However, detection of arseniferous aquifers in Bihar within the past five years, apart from presenting one of the most daunting health challenges to Indian authorities, exemplify how ground water quality has been compromised with on account of its unplanned and excessive utilisation in domestic and agricultural sectors. This has impacted upon the general health conditions of the people. Arsenic level up to 1861 ppb. in drinking water hand pumps had been confirmed in 2004, and very limited epidemiological studies on arsenocosis have been conducted in Bihar till date. More important is the confirmation of the continuous extent of arsenic contaminated ground water upstream from the Bengal Basin.
This study is based on intensive tests carried out on water samples drawn from hand pumps that are used for direct human consumption in the rural areas of four districts of Bihar – Patna, Bhojpur, Vaishali and Bhagalpur- all of which lie along river Ganga. Recent geochemical study supports the hypothesis that arsenic contamination is more frequent and intense in areas of newer alluvium, which areas in Bihar also form zones of high rural population density.
AIM OF THIS STUDY –
To facilitate the recently introduced mitigation strategies by -
Determining the quantum of population at risk in villages with arsenic affected aquifers.
Classifying the villages on the basis of an index of vulnerability to arsenic poisoning.
Obtaining feedbacks regarding the sustainability of the mitigation strategies, initiated by the stakeholders in the affected areas.
METHODOLOGY –
§ The ground water samples of over 28,000 hand pumps in the four districts were collected by this PROJECT ARSENIC group in 2004 – 2005. The study area was confined to 10 km. in Patna, and five km. in the remaining four districts, based upon the frequency of arsenic contamination.
§ While field test kits were used for initial determination on arsenic content, subsequent confirmatory tests were carried through Atomic and UV Spectrophotometers.
§ Questionnaires were distributed for obtaining information regarding the time span of ground water consumption in the affected villages, the depth of the hand pumps, nutrition and health problems.
§ Census of India, 2001, of Govt. of India was referred to gauge the number of persons residing in the areas of arsenic hotspots. However, since the areas of annual inundation are also subject river bank erosion, certain villages within the study area have been relocated to adjacent higher grounds in the form of smaller compact settlements, and hence find no mention in the Census 2001 records. The population totals of such villages were obtained from the “village headman”.
§ Topographical maps and Administrative Block maps were extensively used to determine the spatial spread of contaminated pumps, while G.P.S. data of arsenic hotspots were recorded.
§ Total population and percentage of contaminated hand pumps in each village were considered in deriving an index of population vulnerable to arsenic poisoning, ranging from 1 to 10. Villages with 10 ppb. and less arsenic contamination, and clean pumps were not included in the analysis.
§ This database, along with socio-economic information obtained during field visits, were used in preparing this analysis for gaining insights into the population at risk and the sustainability of different mitigation options adopted.
FINDINGS –
The total study belt bears an approximate population of 3,590,363 persons, of which 1,619,527 [45.10%] reside in villages bearing arsenic contaminated aquifers of over 10 ppb. arsenic content. In Patna, the geographical extent of contaminated aquifers was largely confined to north-western and west central district, whereas sporadic instances of moderate to high contamination levels were found in its eastern part. Concentration of population distribution is influenced by proximity to the state capital of Patna, accounting also for the greater frequency and usage of hand pumps for drinking water purposes. Bhojpur had a much diffused spread of population away from the river bank – a feature that can be attributed to rapid erosion of the river bank in this sector. Conversely, annual inundation along the river bank forced number of villages to migrate away from the river bank in the northern district of Vaishali. Hence both flooding and bank erosion influenced habitation sites in the study area.
The accessibility of the population to contaminated sources varied with variations in the numbers and areal spread of contaminated hand pumps. Hence there were villages with over 26,000 persons with 28 contaminated drinking water hand pumps, as well as an instance where a population of only 1500 were accessing 32 contaminated hand pumps. A total of 7747 hand pumps supplying drinking water were counted, of which 3724 or 48%, were in Patna and Bhojpur. A large number of this were located in a densely populated contiguous belt from North-western Patna to Bhojpur in the west., covering a rough geographical length of about 50 kms. About 728,787 [45%] persons of all the arsenic affected villages were identified as vulnerable, the largest numbers inhabiting the floodplains of Bhagalpur and Patna.
MID GANGA PLAIN OF BIHAR, INDIA: POPULATION AT RISK
IN THE AREAS OF ARSENIC CONTAMINATED AQUIFERS
DISTRICTS
No. of contaminated
Sources in
Affected villages
Population vulnerable to
Arsenic toxicity
[approx.]
% of
population
in study belt
PATNA
1588
251,788
66.34
BHOJPUR
2136
117,609
33.84
VAISHALI
1513
65,062
28.75
BHAGALPUR
2510
294,338
45.35
The index of vulnerability to arsenic poisoning in each district’s study area revealed that high risk group villages peaked up, except in Vaishali where there was a progressive decline from low risk villages to high risk ones. Reversal in declining trend in the high risk group is highest in Patna followed by Bhojpur.
Although the high risk index is highest in the eastern district of Bhagalpur, the contiguous belt of the same in the two adjacent districts of Patna and Bhojpur qualifies the latter as the worst arsenic contaminated area in the study region. This is supported by the highest arsenic levels [Bhojpur-1861ppb., Patna-724 ppb] recorded in these 2 districts. Bhagalpur had larger “moderately high” population at risk, as compared to other districts. The low risk index, too, includes severely contaminated [50 ppb+] sources, but their proportion to the total village population accessing all the hand pumps is low thereby reducing number of persons at risk. However the largest number of villages surveyed belongs to this low risk group, which enhances the possibility of future aggravation of arsenic poisoning.
MID GANGA PLAIN OF BIHAR, INDIA: DISTRICT-WISE INDEX OF POPULATION
VULNERABLE TO ARSENIC POISONING
INDEX→
Upto 4
[low risk]
4 – 6
[moderate]
6 – 8
[moderately high]
8 – 10
[high risk]
PATNA
53
17
08
19
BHOJPUR
75
22
20
30
VAISHALI
59
09
08
02
BHAGALPUR
69
17
27
28
TOTAL NO. OF
VILLAGES
252
67
63
81
DISTRICT –WISE ANALYSIS OF VULNERABILITY INDEX –
Patna district – The general trend of vulnerable rural population declined from west to east and away from the river bank. Sampatchak was the sole exception wherein there was widespread diffuse contamination in almost all villages, and the contamination spread to the western adjacent Phulwari block. This contamination cluster stood isolated in the area south of Patna block. Sampatchak contaminations had the largest spatial spread, covering almost 75% of the block, but its lower population concentration reduced its vulnerability index.
PATNA DISTRICT, BIHAR: BLOCK-WISE INDEX OF POPULATION
VULNERABLE TO ARSENIC POISONING
INDEX→
BLOCKS
Upto 4
[population at
low risk]
4 – 6
Population at
[moderate
risk]
6 – 8
[population at
moderately
high risk]
8 – 10
[population at
high risk]
MANER
08
04
05
09
DANAPUR
04
-
01
04
SAMPATCHAK
06
07
01
03
PHULWARI
05
-
-
01
BAKHTIYARPUR
12
02
01
-
BARH
03
-
-
01
MOKAMA
06
01
-
-
PANDARAK
04
01
-
01
FATUA
02
02
-
-
KHUSRUPUR
03
-
-
-
TOTAL VILLAGES
53
17
08
19
The entire strip of new alluvial deposits, wherever inhabited, yielded arsenic contaminated waters at frequent intervals at shallow depths. High risk index was considerable in Maner and Danapur, putting around 50 % of the villages in this group.
Bhojpur district – Trends in Patna continued into this western district, the only difference being maximum detection of arsenic in the older alluvial terraces about 3 kms. south from the river bank. Higher agricultural productivity and increased incomes permitted the farmers to obtain drinking water from greater depths, but arsenic were detected in aquifers of different depths. Frequency of arseniferous aquifers was highest in Barhara, thereby jeopardising the general health parameters of the area. The number of villages bearing low vulnerability index was also much more in Barhara and Shahpur. More important is the intensity and areal spread of the contamination in these two blocks. Over 31% of the district population is being exposed to 47.42 % hand pumps which have arsenic ranging from 05 ppb to 1861 ppb. [AAS Data].
.BHOJPUR DISTRICT, BIHAR: BLOCK-WISE INDEX OF POPULATION
VULNERABLE TO ARSENIC POISONING
INDEX→
BLOCKS
Upto 4
[population at
low risk]
4 – 6
Population at
[moderate
risk]
6 – 8
[population at
moderately
high risk]
8 – 10
[population at
high risk]
BARHARA
24
13
09
16
SHAHPUR
24
05
05
05
BEHEA
09
02
03
06
UDWANTNAGAR
01
01
02
-
ARA
05
-
01
02
KOILWAR
08
01
-
01
TOTAL VILLAGES
71
22
20
30
In Shahpur, the vulnerability was more in the western part and in the south where the contaminated aquifers continue into north-eastern corner of Behea, that fell within the study area. Further investigations are required into the southern spread of the contaminations for assessing the affected population in Behea. In other blocks, sporadic contaminated aquifers accounted for fewer number of villages in the population risk groups
Vaishali district - All the hand pumps of the riverine island of Raghopur tested positive for arsenic contamination. However, just 17% of the sources had more than 10 ppb. arsenic, so that a comparatively limited number of persons were in the vulnerability index in the 10 affected villages. Hajipur had the highest number of population at risk in its 34 villages in the entire district.. The risk increased towards the east in Sahdai Buzurg, where 2 villages had populations in the high risk group.
VAISHALI DISTRICT, BIHAR: BLOCK-WISE INDEX OF POPULATION
VULNERABLE TO ARSENIC POISONING
INDEX→
BLOCKS
Upto 4
[population at
low risk]
4 – 6
Population at
[moderate
risk]
6 – 8
[population at
moderately
high risk]
8 – 10
[population at
high risk]
RAGHOPUR
10
-
-
-
HAJIPUR
29
03
02
-
BIDUPUR
07
-
02
-
SAHDAI BUZURG
10
03
02
02
DESRI
03
03
02
-
TOTAL
59
09
08
02
Bhagalpur district - Lying adjacent to the Bengal Basin, Bhagalpur exemplifies the upstream continuation of Bengal’s arsenic contaminated aquifers. It had the largest number of villages above index 6. Here even open wells tested positive [Nathnagar] . This district had very few safe villages in contrast to Bhojpur, which severely limits the search for arsenic free hand pumps.
BHAGALPUR DISTRICT, BIHAR: BLOCK-WISE INDEX OF POPULATION
VULNERABLE TO ARSENIC POISONING
INDEX→
BLOCKS
0.01-4.0
[low risk]
4.01 – 6.0
[moderate
risk]
6.01 – 8.0
[moderately
high risk]
8.01 – 10.0
high risk]
KAHALGAON
08
07
06
10
NATHNAGAR
19
02
03
06
SABOUR
09
02
06
03
PIRPAINTI
16
03
12
10
SULTANGANJ
17
03
-
01
TOTAL
69
17
27
30
IMPACT ON HUMAN HEALTH -
The general health of the people was affected by persistent poverty and lack of sufficient nutrition, facts which lowered their resistance to diseases.
During field trips it was observed that the population, in general, was suffering from itching all over their skin, and also had digestion problems. A number of people were found having spots all over their torso. Skin lesions, discoloration of skin, nodules over thickened soles and, in some cases, all over the body were recorded on camera. Initial symptoms bore stark resemblance to the pictures of bodily symptoms obtained from arsenic affected areas of Bangladesh and Bengal. However, clinical examination is urgently required to substantiate these observations. Another point to be noted is that the comparatively low frequency of visible symptoms can be attributed to the fact that arsenicosis symptoms are detected usually after prolonged exposure. Also, most of these affected habitation sites were relatively new settlements, following flooding of the older villages, that have emerged on the meander beds of the Ganga. The population of the entire study area complained of non-response of most of their health symptoms to conventional medicines.
CURRENT MITIGATION STRATEGY –
Based upon the initial intensive detection of arsenic contaminated aquifers in the 4 districts by this study group, the State Government , with financial assistance from the Centre and international organizations, initiated mitigation work based upon providing alternate sources of safe drinking water, that include –
Rain water harvesting – this study group observed that villagers had a psychological barrier in drinking water collected from rooftops. Moreover, due to lack of maintenance, the stored water emitted foul smell, making the communities reject the water even for non-drinking purpose.
Revival of old dug wells in Bhojpur, Patna and Vaishali – the authorities took the initiative to clean and cover the wells and install hand pumps. Here too, less number of wells have not been able to meet the demand. Moreover, the villagers were reluctant to consume well water as they were habituated in consuming bacteria-free ground water.
Adequate infrastructure created for drawing water from safe, deeper aquifers – the success of this project has been severely compromised due to perennial shortage of power supply in rural areas.
RECOMMENDATIONS-
The above mitigation measures can be improved by increasing community participation through creation of awareness of this problem, providing adequate training for maintaining the above schemes, and harnessing alternate energy sources like solar power. Community participation will also increase prospects of employability and accountability, so as to sustain these schemes
Apart from this, district-level monitoring laboratories have been established, but more such centers are required to cope with the growing demand of water testing. Pathological laboratories and health centers need to be established to determine and treat arsenicosis symptoms.
Additional database relating to seasonal monitoring of arsenic contamination levels, checking of safe pumps, and health statistics need to be created even to contain the population at risk.
The stakeholders may use the target villages identified through the Vulnerability index to enable them to prioritize sustainable and cost-effective mitigation strategy in each affected area.
References:
29-31 August, 2007 Paper-2
------------------------------------------------------------------------------------------------------------------
(2) VULNERABILITY OF POPULATION EXPOSED TO ARSENIC CONTAMINATION IN THE MID GANGA PLAIN OF BIHAR, INDIA
Dr. Ashok Kumar Ghosh, Prof.-in-Charge, Dept. of Environment and Water Management A.N.College, Patna nupur.bose@gmail.com
Dr. Nupur Bose, Lecturer, Dept. of Geography, A.N.College, Patna, India
Dr. Narendra Kumar Roy, Resource Person, Dept. of Environment and Water Management A.N.College, Patna, Bihar
Dr. Ajay Upadhyay, Resource Person, Dept. of Environment and Water Management A.N.College, Patna, India
Mr. Amardeep Singh, Research Scholar, Dept. of Environment and Water Management A.N.College, Patna, India
Mr. Sushant Kumar Singh, Research Scholar, Dept. of Environment and Water Management A.N.College, Patna, India
Arsenic contaminated aquifers, being used for direct and indirect human consumption, have severe health implications among the rural population in the state on Bihar, India. This study covered a 10 km. belt along the Ganga river in the four districts of Bhojpur, Patna, Vaishali and Bhagalpur. The purpose of this research was to obtain the distribution and quantum of human population at risk of arsenic poisoning and population composition characteristics of the arsenic-affected belt. The methodology adopted was based upon self-generated and confirmed primary data on abnormally high arsenic concentration in ground water ranging from above 10 ppb. to 1861 ppb. Percentage of hand pumps testing with more than 10 ppb. arsenic content were calculated. This data was compared with the Census 2001 data to obtain estimates of affected population, while Topographical and Administrative Block Maps of all four districts were referred to for studying the spatial pattern of this population. The result showed that approximately 1,537,426 persons [about 47% of the population] residing in the study belt are at risk. In Bhagalpur study belt, the vulnerability extends to more than 75% of the population. Symptoms of arsenic poisoning are widespread, especially among child population. Appropriate mitigation strategies are yet to be undertaken in this study area.
INTRODUCTION –
Bihar is located entirely in the Ganga drainage basin, the geographical extent being 240 20’N to 270 31’15”N, and 830 19’50” E to 880 17’40”E longitudes. Bihar is the second most densely populated state of India having 82,878,769 persons, 89.53% of which is rural population. The per capita income of this economically backward state is a meagre , and it is largely sustained by its agriculture-driven economy. The physical geography of these plains, characterised by annual inundations and frequent meander changes in the river network, generally force rural inhabitants to relocate their habitation sites, particularly in central and north Bihar. It has also resulted in emergence of new areas of alluvial deposits. The presence of ample surface and ground water sources generally confined the problem of water resource to management of flood situations till the last decade. However, detection of arseniferous aquifers in Bihar within the past five years, apart from presenting one of the most daunting health challenges to Indian authorities, exemplify how ground water quality has been compromised with on account of its unplanned and excessive utilisation in domestic and agricultural sectors. This has impacted upon the general health conditions of the people. Arsenic level up to 1861 ppb. in drinking water hand pumps had been confirmed in 2004, and very limited epidemiological studies on arsenocosis have been conducted in Bihar till date. More important is the confirmation of the continuous extent of arsenic contaminated ground water upstream from the Bengal Basin.
This study is based on intensive tests carried out on water samples drawn from hand pumps that are used for direct human consumption in the rural areas of four districts of Bihar – Patna, Bhojpur, Vaishali and Bhagalpur- all of which lie along river Ganga. Recent geochemical study supports the hypothesis that arsenic contamination is more frequent and intense in areas of newer alluvium, which areas in Bihar also form zones of high rural population density.
AIM OF THIS STUDY –
To facilitate the recently introduced mitigation strategies by -
Determining the quantum of population at risk in villages with arsenic affected aquifers.
Classifying the villages on the basis of an index of vulnerability to arsenic poisoning.
Obtaining feedbacks regarding the sustainability of the mitigation strategies, initiated by the stakeholders in the affected areas.
METHODOLOGY –
§ The ground water samples of over 28,000 hand pumps in the four districts were collected by this PROJECT ARSENIC group in 2004 – 2005. The study area was confined to 10 km. in Patna, and five km. in the remaining four districts, based upon the frequency of arsenic contamination.
§ While field test kits were used for initial determination on arsenic content, subsequent confirmatory tests were carried through Atomic and UV Spectrophotometers.
§ Questionnaires were distributed for obtaining information regarding the time span of ground water consumption in the affected villages, the depth of the hand pumps, nutrition and health problems.
§ Census of India, 2001, of Govt. of India was referred to gauge the number of persons residing in the areas of arsenic hotspots. However, since the areas of annual inundation are also subject river bank erosion, certain villages within the study area have been relocated to adjacent higher grounds in the form of smaller compact settlements, and hence find no mention in the Census 2001 records. The population totals of such villages were obtained from the “village headman”.
§ Topographical maps and Administrative Block maps were extensively used to determine the spatial spread of contaminated pumps, while G.P.S. data of arsenic hotspots were recorded.
§ Total population and percentage of contaminated hand pumps in each village were considered in deriving an index of population vulnerable to arsenic poisoning, ranging from 1 to 10. Villages with 10 ppb. and less arsenic contamination, and clean pumps were not included in the analysis.
§ This database, along with socio-economic information obtained during field visits, were used in preparing this analysis for gaining insights into the population at risk and the sustainability of different mitigation options adopted.
FINDINGS –
The total study belt bears an approximate population of 3,590,363 persons, of which 1,619,527 [45.10%] reside in villages bearing arsenic contaminated aquifers of over 10 ppb. arsenic content. In Patna, the geographical extent of contaminated aquifers was largely confined to north-western and west central district, whereas sporadic instances of moderate to high contamination levels were found in its eastern part. Concentration of population distribution is influenced by proximity to the state capital of Patna, accounting also for the greater frequency and usage of hand pumps for drinking water purposes. Bhojpur had a much diffused spread of population away from the river bank – a feature that can be attributed to rapid erosion of the river bank in this sector. Conversely, annual inundation along the river bank forced number of villages to migrate away from the river bank in the northern district of Vaishali. Hence both flooding and bank erosion influenced habitation sites in the study area.
The accessibility of the population to contaminated sources varied with variations in the numbers and areal spread of contaminated hand pumps. Hence there were villages with over 26,000 persons with 28 contaminated drinking water hand pumps, as well as an instance where a population of only 1500 were accessing 32 contaminated hand pumps. A total of 7747 hand pumps supplying drinking water were counted, of which 3724 or 48%, were in Patna and Bhojpur. A large number of this were located in a densely populated contiguous belt from North-western Patna to Bhojpur in the west., covering a rough geographical length of about 50 kms. About 728,787 [45%] persons of all the arsenic affected villages were identified as vulnerable, the largest numbers inhabiting the floodplains of Bhagalpur and Patna.
MID GANGA PLAIN OF BIHAR, INDIA: POPULATION AT RISK
IN THE AREAS OF ARSENIC CONTAMINATED AQUIFERS
DISTRICTS
No. of contaminated
Sources in
Affected villages
Population vulnerable to
Arsenic toxicity
[approx.]
% of
population
in study belt
PATNA
1588
251,788
66.34
BHOJPUR
2136
117,609
33.84
VAISHALI
1513
65,062
28.75
BHAGALPUR
2510
294,338
45.35
The index of vulnerability to arsenic poisoning in each district’s study area revealed that high risk group villages peaked up, except in Vaishali where there was a progressive decline from low risk villages to high risk ones. Reversal in declining trend in the high risk group is highest in Patna followed by Bhojpur.
Although the high risk index is highest in the eastern district of Bhagalpur, the contiguous belt of the same in the two adjacent districts of Patna and Bhojpur qualifies the latter as the worst arsenic contaminated area in the study region. This is supported by the highest arsenic levels [Bhojpur-1861ppb., Patna-724 ppb] recorded in these 2 districts. Bhagalpur had larger “moderately high” population at risk, as compared to other districts. The low risk index, too, includes severely contaminated [50 ppb+] sources, but their proportion to the total village population accessing all the hand pumps is low thereby reducing number of persons at risk. However the largest number of villages surveyed belongs to this low risk group, which enhances the possibility of future aggravation of arsenic poisoning.
MID GANGA PLAIN OF BIHAR, INDIA: DISTRICT-WISE INDEX OF POPULATION
VULNERABLE TO ARSENIC POISONING
INDEX→
Upto 4
[low risk]
4 – 6
[moderate]
6 – 8
[moderately high]
8 – 10
[high risk]
PATNA
53
17
08
19
BHOJPUR
75
22
20
30
VAISHALI
59
09
08
02
BHAGALPUR
69
17
27
28
TOTAL NO. OF
VILLAGES
252
67
63
81
DISTRICT –WISE ANALYSIS OF VULNERABILITY INDEX –
Patna district – The general trend of vulnerable rural population declined from west to east and away from the river bank. Sampatchak was the sole exception wherein there was widespread diffuse contamination in almost all villages, and the contamination spread to the western adjacent Phulwari block. This contamination cluster stood isolated in the area south of Patna block. Sampatchak contaminations had the largest spatial spread, covering almost 75% of the block, but its lower population concentration reduced its vulnerability index.
PATNA DISTRICT, BIHAR: BLOCK-WISE INDEX OF POPULATION
VULNERABLE TO ARSENIC POISONING
INDEX→
BLOCKS
Upto 4
[population at
low risk]
4 – 6
Population at
[moderate
risk]
6 – 8
[population at
moderately
high risk]
8 – 10
[population at
high risk]
MANER
08
04
05
09
DANAPUR
04
-
01
04
SAMPATCHAK
06
07
01
03
PHULWARI
05
-
-
01
BAKHTIYARPUR
12
02
01
-
BARH
03
-
-
01
MOKAMA
06
01
-
-
PANDARAK
04
01
-
01
FATUA
02
02
-
-
KHUSRUPUR
03
-
-
-
TOTAL VILLAGES
53
17
08
19
The entire strip of new alluvial deposits, wherever inhabited, yielded arsenic contaminated waters at frequent intervals at shallow depths. High risk index was considerable in Maner and Danapur, putting around 50 % of the villages in this group.
Bhojpur district – Trends in Patna continued into this western district, the only difference being maximum detection of arsenic in the older alluvial terraces about 3 kms. south from the river bank. Higher agricultural productivity and increased incomes permitted the farmers to obtain drinking water from greater depths, but arsenic were detected in aquifers of different depths. Frequency of arseniferous aquifers was highest in Barhara, thereby jeopardising the general health parameters of the area. The number of villages bearing low vulnerability index was also much more in Barhara and Shahpur. More important is the intensity and areal spread of the contamination in these two blocks. Over 31% of the district population is being exposed to 47.42 % hand pumps which have arsenic ranging from 05 ppb to 1861 ppb. [AAS Data].
.BHOJPUR DISTRICT, BIHAR: BLOCK-WISE INDEX OF POPULATION
VULNERABLE TO ARSENIC POISONING
INDEX→
BLOCKS
Upto 4
[population at
low risk]
4 – 6
Population at
[moderate
risk]
6 – 8
[population at
moderately
high risk]
8 – 10
[population at
high risk]
BARHARA
24
13
09
16
SHAHPUR
24
05
05
05
BEHEA
09
02
03
06
UDWANTNAGAR
01
01
02
-
ARA
05
-
01
02
KOILWAR
08
01
-
01
TOTAL VILLAGES
71
22
20
30
In Shahpur, the vulnerability was more in the western part and in the south where the contaminated aquifers continue into north-eastern corner of Behea, that fell within the study area. Further investigations are required into the southern spread of the contaminations for assessing the affected population in Behea. In other blocks, sporadic contaminated aquifers accounted for fewer number of villages in the population risk groups
Vaishali district - All the hand pumps of the riverine island of Raghopur tested positive for arsenic contamination. However, just 17% of the sources had more than 10 ppb. arsenic, so that a comparatively limited number of persons were in the vulnerability index in the 10 affected villages. Hajipur had the highest number of population at risk in its 34 villages in the entire district.. The risk increased towards the east in Sahdai Buzurg, where 2 villages had populations in the high risk group.
VAISHALI DISTRICT, BIHAR: BLOCK-WISE INDEX OF POPULATION
VULNERABLE TO ARSENIC POISONING
INDEX→
BLOCKS
Upto 4
[population at
low risk]
4 – 6
Population at
[moderate
risk]
6 – 8
[population at
moderately
high risk]
8 – 10
[population at
high risk]
RAGHOPUR
10
-
-
-
HAJIPUR
29
03
02
-
BIDUPUR
07
-
02
-
SAHDAI BUZURG
10
03
02
02
DESRI
03
03
02
-
TOTAL
59
09
08
02
Bhagalpur district - Lying adjacent to the Bengal Basin, Bhagalpur exemplifies the upstream continuation of Bengal’s arsenic contaminated aquifers. It had the largest number of villages above index 6. Here even open wells tested positive [Nathnagar] . This district had very few safe villages in contrast to Bhojpur, which severely limits the search for arsenic free hand pumps.
BHAGALPUR DISTRICT, BIHAR: BLOCK-WISE INDEX OF POPULATION
VULNERABLE TO ARSENIC POISONING
INDEX→
BLOCKS
0.01-4.0
[low risk]
4.01 – 6.0
[moderate
risk]
6.01 – 8.0
[moderately
high risk]
8.01 – 10.0
high risk]
KAHALGAON
08
07
06
10
NATHNAGAR
19
02
03
06
SABOUR
09
02
06
03
PIRPAINTI
16
03
12
10
SULTANGANJ
17
03
-
01
TOTAL
69
17
27
30
IMPACT ON HUMAN HEALTH -
The general health of the people was affected by persistent poverty and lack of sufficient nutrition, facts which lowered their resistance to diseases.
During field trips it was observed that the population, in general, was suffering from itching all over their skin, and also had digestion problems. A number of people were found having spots all over their torso. Skin lesions, discoloration of skin, nodules over thickened soles and, in some cases, all over the body were recorded on camera. Initial symptoms bore stark resemblance to the pictures of bodily symptoms obtained from arsenic affected areas of Bangladesh and Bengal. However, clinical examination is urgently required to substantiate these observations. Another point to be noted is that the comparatively low frequency of visible symptoms can be attributed to the fact that arsenicosis symptoms are detected usually after prolonged exposure. Also, most of these affected habitation sites were relatively new settlements, following flooding of the older villages, that have emerged on the meander beds of the Ganga. The population of the entire study area complained of non-response of most of their health symptoms to conventional medicines.
CURRENT MITIGATION STRATEGY –
Based upon the initial intensive detection of arsenic contaminated aquifers in the 4 districts by this study group, the State Government , with financial assistance from the Centre and international organizations, initiated mitigation work based upon providing alternate sources of safe drinking water, that include –
Rain water harvesting – this study group observed that villagers had a psychological barrier in drinking water collected from rooftops. Moreover, due to lack of maintenance, the stored water emitted foul smell, making the communities reject the water even for non-drinking purpose.
Revival of old dug wells in Bhojpur, Patna and Vaishali – the authorities took the initiative to clean and cover the wells and install hand pumps. Here too, less number of wells have not been able to meet the demand. Moreover, the villagers were reluctant to consume well water as they were habituated in consuming bacteria-free ground water.
Adequate infrastructure created for drawing water from safe, deeper aquifers – the success of this project has been severely compromised due to perennial shortage of power supply in rural areas.
RECOMMENDATIONS-
The above mitigation measures can be improved by increasing community participation through creation of awareness of this problem, providing adequate training for maintaining the above schemes, and harnessing alternate energy sources like solar power. Community participation will also increase prospects of employability and accountability, so as to sustain these schemes
Apart from this, district-level monitoring laboratories have been established, but more such centers are required to cope with the growing demand of water testing. Pathological laboratories and health centers need to be established to determine and treat arsenicosis symptoms.
Additional database relating to seasonal monitoring of arsenic contamination levels, checking of safe pumps, and health statistics need to be created even to contain the population at risk.
The stakeholders may use the target villages identified through the Vulnerability index to enable them to prioritize sustainable and cost-effective mitigation strategy in each affected area.
References:
Arsenic in Bihar
Annual Conference 2007, Royal Geographical Society, London Session key: BSG-session 3
29-31 August, 2007 Paper-5
Arsenic contaminated aquifers: a study of the Ganga levee zones in Bihar, India
A.K.Ghosh1. S.K..Singh2, Nupur Bose3, S. Chaudhary4
1 Department of Environment and Water Management, A.N.College, Patna
2 Department of Environment and Water Management, A.N.College, Patna
3 Department of Geography, A.N.College, Patna, India
4 Department of Botany, T.M.Bhagalpur University, Bhgalpur, India
ABSTRACT-
'In Bihar Plains, ground water is the most important source of drinking and irrigation water. The purpose of this interdisciplinary study, undertaken along the levee of river Ganga in the Mid Ganga Plain, was to determine the existence and intensity of arsenic contamination in aquifers being tapped for direct and indirect ingestion of the properties of the region’s ground water, in the four districts of Bihar [India], i.e., Patna, Bhojpur, Vaishali and Bhagalpur. The methodology involved formulation of a protocol for arsenic detection in ground water, use of Field Test Kits for initial detection, obtaining GPS coordinates of arsenic hotspots for spatial analysis of the problem, and confirmatory testing of arsenic hot samples by U.V., and Atomic Absorption Spectrophotometry. Water samples of 28000 private and government owned hand pumps were tested. Many arsenic hotspots were detected in all the four districts, the coordinates of which were recorded by GPS. Arsenic contamination up to 1861 ppb. was found in the western district of Bhojpur, against the W.H.O. permissible limit of 10 ppb. The greatest frequency of contaminated hand pumps was noted in the eastern district of Bhagalpur. Sharp spatio-temporal variations of contamination levels were detected in this densely populated study belt.
Introduction
Arsenic is one of the less abundant metalloids forming the earth’s crust. Its important physico-chemical characteristic is that it is commonly concentrated in sulphide-bearing mineral deposits, pyrites and hydrous iron oxides1,2. Its presence in ground water sources is attributed to a number of natural and anthropogenic causes, based on its property of solubilizing in ground waters “depending on pH, redox conditions, and temperature and solution composition”3. Main sources of arsenic in aquifers include organic carbon or black shales, Holocene alluvial deposits, and volcanic sources4. Of particular relevance to this study, is the “strongly reducing, arsenic-rich aquifers”5 of the young alluvial sediments of the Mid Ganga Plains. Arsenic occurs widely in aquifers of deltaic sediments6, near zones of orogeny, and in deep sandy aquifer layers7 as fluvial deposits. It is introduced into the aquifer sediments in soluble state and gets adsorbed on iron-rich clastic grains and authigenic siderite concentrations. The adsorption process and its consequent desorption are stated to be controlled by microbial activity within the concerned aquifers8. Sediments containing 1 to 20 ppb. of arsenic can give rise to high dissolved arsenic of >50 ppb. by one or both of two possible causes – an increase of pH of over 8.5 or the onset of reductive iron dissolution3. Also, presence of solutes can also decrease or prevent the adsorbtion of arsenate and arsenite ions onto fine grained clays, like iron oxides8. Additional processes promoting high arsenic content in ground water are oxidation and dissolution of arsenian pyrite, Fe[As,S]2, and arsenopyrite [HN8], FeAsS9. Oxidation occurs either by infiltration of oxygenated ground waters10, or by lowering of ground water table into a stratigraphic zone of arsenic –rich sulphides11.
There are two main theories as to how arsenic is released into the groundwater -
Pyrite oxidation: In response to pumping, air or water with dissolved oxygen penetrates into the ground, leading to decomposition of the sulphide minerals and release of arsenic.
Oxyhydroxide reduction: Arsenic was naturally transported in the river systems of Bangladesh adsorbed onto fine-grained iron or manganese oxyhydroxides. These were deposited in flood plains and buried in the sedimentary column. Due to the strongly reducing conditions which developed in the sediments and groundwater of certain parts of Bangladesh the arsenic was released into groundwater. The release mechanism is still hotly debated but the second theory is thought to be the more likely explanation.
Our recent hydrochemical study of groundwater arsenic along transects from the foothill alluvium to the Indian Shield exposed in Mid Ganga Basin indicate that As concentrations are much higher in groundwater collected from the youngest alluvial terraces (~50% samples have 0.01 mg/L [WHO Maximum Contaminant Level] As, maximum 0.52 mg/L), than those associated with the shield (all 0.005 mg/L). Most (87%) of the As is present as As(III) 12.
Arsenic toxicity
Arsenic is highly toxic carcinogen (Category I) and also a mutagen / teratogen (harming foetus). Arsenic in ground water that is used for human consumption water, poses the greatest threat to public health13. Reliable data on exposure and health effects are rarely available, but it is clear that there are many countries in the world where arsenic in drinking water has been detected at concentrations greater than the WHO Guideline Value, 0.01 mg/L or the prevailing national standards. These include Argentina, Australia, Bangladesh, Chile, China, Hungary, Mexico, Peru, the United States of America and some countries in the South-East Asia Region. The arsenic crisis in Bangladesh has been described as one of the worst cases of mass poisoning in world history. Studies from West Bengal in India show that approximately 5 million persons are consuming groundwater containing arsenic exceeding 0.05 mg/L. Recent unconfirmed reports point to the presence of arsenic in Tamil Nadu and other states of India, implying industrial contamination of groundwater. In India, it is estimated that 220 000 of the 5 million exposed subjects are showing signs of arsenicosis.
W.H.O.14 has published Guidelines for Drinking Water Quality in which a contemporary value for an acceptable maximum level of Arsenic was set at 10 ug/l/ for safe water. National standards range from 7 ug/l in Australia to 50 ug/l in Vietnam, Cambodia and Bangladesh15.
Long-term oral exposure via drinking water can cause cancer of the skin16, lungs, urinary bladder, and kidneys. With long term exposure the first changes are usually seen in the skin pigments (indicator of arsenic poisoning), then hyperkeratosis. Symptoms of chronic arsenic poisoning can take five to 15 years to appear and are apparently influenced by nutrition and general health standards24. Increased risks of lung and bladder cancer and of skin lesions have been observed at arsenic concentrations of less than 0.05 mg / L of drinking water..
Statement of the problem-
Naturally occurring Arsenic, as a water quality issue in South Asia, began to attract international attention in the early decade of the nineties, when widespread chronic arsenic poisoning cases became apparent in Bangladesh and later in West Bengal, India17,18. Arsenic pollution in groundwater in this part of the subcontinent is a contentious issue. Investigations into the causation of arsenic pollution require a multidisciplinary approach19.
Later, the discovery of arseniferrous aquifers in Simaria-Ojhapatti village under Shahpur Block in Bhojpur, Bihar, located further upstream of the Bengal basin in 2003, raised apprehensions about the greater spatial spread of this dreaded contamination along the Ganga Valley.
In 2002, School of Environmental Studies, Jadavpur University, detected arsenic levels higher than the Bengal contamination readings. This has made it urgent for further detection of Arsenic infestation in the surrounding aquifers near River Ganga, within Bihar20,21. The study area of this research incorporates Patna District, the justification being its close proximity to Bhojpur District. The two districts are separated by the River Sone which confluences with the Ganga on the northern boundaries of both Bhojpur and Patna. Based on the hypothesis of previous random water analysis about possibilities of contamination in newer fluvial deposits,22, the study area of levee region was confined to an approximate belt of 10 kms. along the southern bank of River Ganga in the districts of Patna, Bhojpur and Bhagalpur; and along the northern bank in Vaishali district,
Methodology-
This research team formulated the Protocol, duly approved by Govt. of Bihar, Govt. of U.P., and UNICEF, for detection of arsenic over large areas. This Protocol is specifically intended for use by all those involved with arsenic detection in hand pumps using field test kits. The methodology incorporated in the Protocol has the following five significant components-
· All the public hand pumps of the study area were tested for Arsenic content through Field Test Kits by trained Staff.
· Each public hand pump tested was marked, with a unique Identification Code at the time of testing. The 13-digit code was derived from the Census 2001. This information identified the State, District, block and village, and finally the serial number of the Hand pump.
· Bihar Plains consist of sandy soils, where recent research has shown that presence of silica often masks the signal of arsenic from many chemicals11, thereby “creating a false optimum” of arsenic content lower than actually existing. Hence, 10% random verification of field test kit results was done through Atomic Absorption Spectroscopy.
· All field test results above 40mg/l were retested using AAS / UV Spectrophotometer23.
· Marking of hand pumps were done to inform the public of their status (safe/unsafe). The color codes applied were – Blue for FTK readings below 40 ppb.; yellow for FTK readings 40- 79 ppb.; and, Red for FTK readings of 80 ppb. and above.
· There is an increasing need to map the level of arsenic concentration, trends of arsenic flow and temporal changes occurring in its concentration levels. Recording the locations of Arsenic-affected hand pumps, using Global Positioning System (GPS) units24, was done, followed by mapping of the arsenic occurrences. The other references used were Block Maps, Topographical Maps.
· Use of field test kits as basic indicator of arsenic contamination -
The initial assessment of ground water arsenic contamination has been done by Field Test Kits designed by National Chemical Laboratory [NCL], Pune,and manufactured by Chem In corporation,Pune. As a reliable testing tool, FTK usage was previously discarded. However, during the Patna Study, the efficacy of FTK was proved by statistical comparison with AAS test results of the same water samples, in Sriram Institute of Industrial Research [SIIR], New Delhi. The SIIR Report on the efficacy of FTK has proved that it is a fast and economical, general indicator of arsenic contamination in water, provided the FTK users are trained technicians with a good idea of laboratory procedures.
F.T.K. Results -
Of the total of 27061 public hand pumps surveyed and sampled by Field Test Kits till date, 5757 hand pumps were contaminated with arsenic of over 10 ppb.. Taking into account the permissible limit of 10 ppb. set by W. H. O, the table below reveals massive contamination in Maner, Danapur, Bakhtiarpur, and Barh blocks [ Patna district]; Barhara and Shahpur blocks [Bhojpur district]; Kahalgaon, Pirpainti and Nathnagar blocks [Bhagalpur district]; and, Raghopur, Hajipur and Sahdai Buzurg[ Vaishali district].. These arsenic hotspots, forming the first group, have been found to be highly concentrated in the DIARA region. It would be not out of place to mention that there seems to be certain continuity in the occurrence of ground water arsenic, from Bhojpur district in the west into Bhgalpur to the east.
However deviations in the contiguity of the arsenic belt was noted in Sampatchak Block in Patna District and in Barhara and Shahpur blocks in Bhojour. Widespread occurrences of low level contaminations of around 50 ppb. in Sampatchak block, 5 km. away from the southern river bank,
In Patna, a fair presence of arsenic above 10 ppb., include Mokama, Sampatchak, Patna, Fatuha and Phulwari. The general areal extent of this contamination is in close proximity to the right bank of river Ganga, except in Sampatchak, where lower arsenic concentrations of 50 ppb. and less were spread over the entire block. While most of the blocks had a considerable number of “safe” or BDL marked hand pumps, the same is of limited proportion in Maner, where largest number of contaminated hand pumps were identified. Except Bihta, Naubatpur, Ghoswari and Daniawan all the blocks had contamination levels of above 10 ppb. to 50 ppb.
FTK Readings of water samples in worst
affected blocks,
Patna District
Sl.
No.
Name of
The Block
11 ppb. and above
1
Maner
38.04%
2
Danapur
26.87%
3
Sampatchak
16.58%
4
Barh
10.60%
5
Bakhtiarpur
14.47%
In Bhojpur, of the 5917 FTK tested samples, arsenic contamination at various levels, have been noted in 2806 samples. Udwantnagar has 100 contaminated sources against 67 “Nil” hand pumps. Barhara, Shahpur and Bihia have the maximium numbers of contaminated samples. The intensity of arsenic content can be best gauged by the. Fact thar Barhara , Shahapur and Bihia collectively spews arsenic rich water [> 50 ppb] from 1381 public hand pumps. Except Ara and Koilwar, the remaining 4 blocks have the largest share of arsenic contamination sources in the >50 ppb class. Conversely, Ara and Koilwar have the largest proportion of arsenic–free hand pumps. The total percentage of arsenic contaminated water samples fall within 3 groups- high contamination of over 50 % [Barhara and Udwantnagar]; moderate contamination of 30% to 50 % [Shahpur and Behea]; and low contaminated occurrences of below 30 % [Ara and Koilwar].
Overall, level of arsenic contamination in public hand pumps is both higher and more widespread than the situation in the neighboring Patna District
FTK Readings of water samples in worst
affected blocks,
Vaishali District
Sl.
No.
Name of the Block
11 ppb. and above
1
Raghopur
17.18
2
Hajipur
55.58
3
Bidupur
71.19
4
Sahdai Buzurg
68.09
5
Desri
68.42
In Vaishali, a total of 8080 water samples were tested by F.T.K.s, of which 18.73% were found to be contaminated. Raghopur was the only block that had 100% contaminated samples, although in comparison to other blocks, a large chunk of contaminated samples fell in the “below 40 ppb.” group. In Hajipur, 61.69% source samples tested arsenic – free, and only 119 [7.57%] of contaminated samples were of 40 ppb. and more. Bidupur, with 81.58% uncontaminated samples, had the largest share of arsenic “NIL” water source. But, a total of 102 [28.81% of contaminated samples] were in the 40 ppb+ range, making this block the most contaminated one. Sahdai Buzurg and Desri had 66.88% and 74.93% uncontaminated samples respectively.
FTK Readings of water samples in worst
affected blocks,
Bhojpur District
Sl.
No.
Name of the Block
11 ppb. and above
1
Barhara
55.35%
2
Shahpur
37.97%
3
Bihia
33.37%
4
Udwant-
Nagar
55.69%
5
Ara
15.23%
6
Koilwar
26.12%
In Bhagalpur District , 8075 hand pumps were subject to FTK tests, of which over 2500 sources tested positive. Kahalgaon and Pirpainti, had the largest number of contaminated drinking water hand pumps, followed by Nathnagar, Sabour and Sultanganj blocks.
FTK Readings of water samples in worst
affected blocks,
Bhagalpur District
Sl.
No.
Name of the Block
11 ppb. and above .*
1
Kahalgaon
48.50 %
2
Pirpainti
43.00%
3
Sabour
31%
4
Nathnagar
11.00%
5
Sultanganj
ANALYSIS OF AAS AND UV SPECTROPHOTOMETER RESULTS-
Out of 6101 samples collected in Patna, 457 samples were retested by AAS-HG method at Sriram Institute of Industrial Research, New Delhi. Of the 457 samples tested there, 390 samples were confirmed to have Arsenic content of over 10 ppb. Samples have tested as having more than 50 ppb. As. content. The highest As. content detected by AAS Method is 724 ppb. , this sample being collected from Naikatola Village, Maner block, in the hand pump located near the house of Mr. Pundev Singh.
In Danapur block the highest As. Level detected by AAS method is 450 ppb. at Kasimchak, from the hand pump located near the house of Mr. Sitaram Rai. The next highest reading of 409 ppb.in this block, is from the hand pump near the house of Mr. Laxman Rai of Harshamchak village, Danapur block.
In Bakhtiarpur, the highest arsenic level detected by AAS method is 553 ppb. in Ghiaspur Mahazi, outside the house of Ashok Mahto, followed by 538 ppb. in Kala Diara, outside the house of Faudar Paswan. In Barh, the highest arsenic level read by AAS is 484 ppb. in Malahi Banda, near the house of Balaj Mahto; and 441ppb. near the house of Mohan Mahto
In Bhojpur, 27.35% of the AAS-tested 457 samples fall within the 50-99 ppb. group, and 25.38% have arsenic content of between 11-49 ppb. Table-3 reveals a tapering down of the number of samples in the successive higher arsenic value groups. Uncontaminated samples were only 10.5%, while another 4.6%samples were within the permissible limit of below 10 ppb. All the four critical l blocks had large numbers of contaminations between 11-99 ppb.
The first list of AAS tested water samples from 656 villages in Barhara and Shahpur Blocks have been obtained. All the villages in this list have hand pumps with more than 10 ppb. Arsenic Content, interspersed with a lesser number of safe hand pumps [Table -15].
In the total of 656 AAS tested samples received till date, the highest values of 1861 and 1064 has been recorded in the houses of Krishna Pandey and Munna Pandey respectively, in village Pandey Tola, Sinha in Barhara. In Shahpur, the highest arsenic contamination of 598 ppb was recorded in the house of Baban Prasad at village Karnamepur.
90.05% the 586 contaminated samples are in the 11ppb. – 500ppb. level. Barhara has 91.07% and Shahpur has 88.75% in this contamination group. The two values of over 1000 ppb. merit serious attention to the Arsenic contamination problem in Barhara.
In Vaishali district, Highest number of contaminated samples was found in the 51-100 ppb. group [142 or 54.44%]. Another 77 FTK samples [28.51%] fell in the 11-50 ppb. group, while 36 samples [13.33%] were of 101-150 ppb. contamination levels. The remaining 15 samples tested more than 151 ppb.UV results of Bidupur show the largest contaminated samples in the 51-100 ppb. group among all the contamination groups of all the blocks. Desri’s water samples ranged between 11-101 – making it the least contaminated of the blocks surveyed
In Bhagalpur
SUMMARY OF AAS/UV SPECTROPHOTOMETER RESULTS
DISTRICT
No. of water sources with
more than
10 ppb. arsenic
Highest reading
Patna
392
724ppb
Bhojpur
656
1861 ppb.
Vaishali
270
360 ppb
Bhagalpur
1402
608 ppb.
Mapping of Arsenic Hotspots in Bihar -
GPS coordinates were obtained for all the hotspots. These were then imposed on the topographical sheets and the spatial parameter was assessed.
A total of 171 villages were surveyed in Patna.. Every block has some degree of arsenic contamination, Maner having more than 40 % of the water samples, and Danapur and Sampatchak with 30-40% of the samples testing positive. Less than 10 % of the samples from only Patna block tested positive. The remaining blocks had varying percentage values in the intermediate range between the two extremes. Sampatchak was the single block with diffuse spread of arsenic contaminated hand pumps - low intensity arsenic contamination exist in almost every village, and the highest reading went upto 50 ppb.
3 Clusters of hotspots were noted – Maner cluster, Danapur Cluster, Bakhtiarpur Cluster and Barh Cluster. All these hotspots were located in the DIARA or floodplains that are subject to annual inundation. Mokama and Pandarak had frequent occurrences of 50 ppb. too. Gradual decreases in the number of highest readings were noted from west to east. Also, arsenic concentrations tapered down towards south, supporting the hypothesis of arsenopyrite oxidation of Holocene sedimentary deposits3, 10. This oxidation has been attributed to excessive withdrawal of ground water by the inhabitants, both for domestic purpose and agricultural use.As one moved away from the riverbank, the frequency of arsenic contaminated sources decreased. Tests were also extended southward along the right bank of river Sone in order to seek spread of contamination. However, all the samples collected from the Sone bank further south of its confluence with the Ganga, tested negative. It can be safely concluded that the menace of Arsenic in ground water exists in Patna district, parallel to the Ganga riverbank, in a broken belt from Maner in the west to Mokama in the east. These findings need further regular monitoring to detect future changes in its extent and intensity.
As per AAS confirmatory test results, Arsenic contaminated sources were found to be greatest in Maner and Danapur blocks and were interpretated through isoline mapping of northwest Patna. The map obtained thus, revealed four concentrations of high arsenic levels, around which decreasing iso-values were interpolated. The resultant pattern is highly indicative of the presence of arsenic rich rock layer within or very close to the major aquifer [[major aquifer depth- 60 to 110 feet] in this area, from where maximum water is withdrawn. This finding needs to be further assessed by possible digging of boreholes, for geochemical analysis, in the peak value spots identified in the map. The space between the Maner and Danapur Clusters are uninhabited, but it falls within the zone of potential arseniferrous aquifers. The peculiarity of this metalloid in Patna is that it is non-existent in open wells, and is absent on, and, beyond the older alluvium of the southern levee.
Choropleth maps were prepared on the basis of FTK data to identify the arsenic hotspots in Bhojpur District. GPS readings were obtained from all the known arsenic affected villages. Barhar and Shahpur blocks had the highest frequency of arsenic contaminated handpumps in almost all the villages.. Behea is contaminated in its north-easterm parts, while Udwantnagar is heavily contaminated in the small area covered. Ara and Koliwar reveal diffuse contamination, though of a lesser intensity than the remaining blocks.
The unpredictable nature of arsenic levels was also revealed. Some villages with more than 75% contaminated hand pumps are located along the southern boundary of the 10 km. belt in Barhara, and Udwantnagar, giving credence to the possibility of arsenic contamination further into the district interiors.
Unlike the Patna contaminations, where there was a tapering down of arsenic content in water away from the Ganga Bank, Bhojpur has widespread arsenic occurrences, that also occur at all aquifer levels accessed by the local population. Repeated high arsenic contamination in Udwantnagar forced the Project Investigator to test water samples of Chhotka Sasaram Village adjacent to the southern boundary of the 10 km. belt, and arsenic contamination was found to be very high. Some of the demarcated villages have been abandoned, and have not been subjected to FTK tests.
North of the Ganga River, arsenic hotspots are more frequent 4 – 5 kms. away from the river bank. Here in Vaishali, riverside contamination with over 50 ppb readings was confined to 3 settlements only. A comparatively larger number of contaminated villages are noted nearer the Gandak River in Hajipur Block.
Although much of Raghopur were covered due to annual inundation, all the samples were contaminated. All villages drinking water sources tested here had a number of above 50 ppb contaminated drinking water sources. There was a concentration of > 40 ppb water sources in the narrow land on the north-eastern part of Raghopur. Bidupur had the minimum contamination [18.34%samples contaminated]. The areal spread of contamination is less than in Hajipur and is more on the northern part of this block. Dot clusters again become frequent in Desri and Sahdai Buzurg Blocks. Readings of over 40 ppb are noted along the northern boundary of the study area, suggesting a further northward spread of arsenic contamination.
Maps also revealed the intensity of contamination levels. Raghopur block had no ‘NIL’ samples, and a large percent of low contamination of below 10 ppb. In all the other blocks, contaminations of 11-39 ppb. are significant.
The FTK data maps of Patna and Bhojpur supported the hypothesis of this research team that the areal spread of ground water arsenic contamination bears some correlation to the occurrence of iron-rich newer fluvial deposits in Bihar; hence its frequency nearer the banks of the Ganga. Vaishali maps reveal a different pattern. There are arsenic occurrences in all the villages surveyed in Raghopur island in the south with a few corresponding occurrences hotspots along the northern banks of the river. Immediately to the north of the bank area, are a series of villages with “NIL” FTK readings. Beyond this, further north is a near-contiguous arsenic contamination belt, with intervening non-surveyed villages, that extends roughly parallel to the river bank in an east-west direction. The belt can be traced from Hajipur in the east to Sahdai Buzurg in the west. It is indicative of serious arsenic contamination beyond the arbitrary 10 km. study belt in northern Bihar. The spatial pattern once again highlights the abruptness and unique spread of arsenic in each district of Bihar and calls for immediate hydro-geological analysis.
The flood-prone “diara” areas of Bhagalpur revealed a spatial pattern similar to that of Patna district, with the number of occurrences decreasing away from the river bank. However, Bhagalpur’s contamination extended to even open-wells in Nathnagar . Continuity of hotspots in Kahalgaon and Pirpainti, gives credence to the fact that arsenic mobilization was advancing upstream from the adjacent Bengal Basin along the eastern boundary of this district.
Recommendations-
• A comprehensive study for arsenic contamination in ground water is urgently required all along the banks of Ganga.
• All hand pumps confirmed as having more than 50 ppb. Arsenic content be capped immediately.
• Efforts should be made also to minimize the intake of water having arsenic content of 10 ppb to 50 ppb.
• Gradual, planned reduction of local permissible limit of 50 ppb. to 10 ppb., to avoid long-term assimilation and accumulation of arsenic among the undernourished child and young population
• Identification ,usage and maintenance of arsenic-free aquifers may be carried out in the affected villages identified by this study on priority basis.
• Provisions for alternate safe sources of drinking water, such as piped water, can be implemented wherever possible.
• Intensive awareness campaign should be initiated in arsenic affected villages, educating them about the scourge. Services of nutritional experts can be harnessed, who can identify nutrition-rich agricultural produce and advice the villagers on how to increase the intake of proteins, vitamins and minerals through increased consumption of such local farm products.
• Supply of low-cost, community-based arsenic filters be provided to the affected villages
• Usage of dug wells, with proper water treatment, can be resumed, as the wells of the surveyed area have not tested positive for arsenic contamination till date.
• In all the mitigation work to be adopted, community participation is a basic prerequisite, as it will aid the stakeholders in effective management of arsenic contaminated drinking water sources
• Clinical investigation be initiated in affected villages by a team of doctors
• There is an urgent need for fully-equipped health centres in the arsenic identified areas.
• Further research through bioremediation by “arsenic munchers”[microbes and ferns] should be encouraged, on the principle that nature’s problems can be overwhelmed by identifying solutions existing within nature itself.
References
1. Wedepohl, K.H., Geochim. 1995, Cosmochim. Acta 59, 1217 .
2. Kolker, A., et al., The U.S. Geological Survey WorkShop on Arsenic in the Environment;
www.brr.cr.usgs.gov/Arsenic/
3. Smedley, P.L., & Kinniburgh, D.G., 2002, Appl. Geochem. 17, 517.
4. Webster, J. & Nordstorm, D.K., Arsenic in Groundwater, [Eds.welch, A.H. & Stollenwerk K.G.],
Kluwer, Amsterdam.
5. Nordstorm, D. Kirk, 2002,Worldwide Occurences of Arsenic in Ground Water, Science, Vol. 269, Issue
5576, p2143.
6. Acharya, S. K.,Chakrabarty, P., et al, 1999, “Arsenic Poisoning in Ganges Delta [ Brief
Communication], Nature, 401: 55.
7. “Interim AusAid Guidelines and Operations Procedures for Managing Arsenic in Water Supplies”.
www.ausaid.gov.au/publications/pdf.arsenicguide_feb04.pdf
8. Pal, T., Mukherjee, P.K., & Sengupta, S., Nature of Arsenic pollutants in groundwater of Bengal Basin-
A case study from Baruipur area, West Bengal, India, Current Science, Vol. 82, No. 5, March 2002
9. Welch,A.H.,et al., Groundwater 38, 589 [2000].
10. Mueller, S., et al., USGS Fact Sheet FS-111-01, November 2001.
11. Schreiber, M.J., et al., Hydrogeol. J. 8, 161 [2000]
12. Mukherji, A., Scanlon, B.R., Ghosh A., et al., Regional Hydrochemical study of groundwater arsenic contamination along transects from the Himalayan alluvial deposits to the Indian Shield, Central Gangetic Basin, India - accepted for presentation in GSA Denver Annual Meeting, October 2007, USA.
13. Chakrabarty, D., “ Arsenic Orphans”, Banabithi, Environmental Special Issue, Dept. of Environment
and Forest, Govt. of West Bengal, India, June 1989, 7-16.
14. The World Bank [1999] , Entering the 21st. Century, World Development Report, 1999-2000, Oxford
University Press, N.Y
15. Fazal, A., Kawachi, T., & Ichion, E., “Extent and Severity of Groundwater Arsenic contamination in
Bangladesh”, International Water Resources Association, Water International, Vol. 26, No. 3, 370-
379, Sept. 2001.
16. Astolfi, E., Maccagno, A., et al, 1981, “Relation between Arsenic in Drinking Water and Skin Cancer”,
Biological Trace Element Research, 3, 133-143.
17. Chaudhary, U.K., Biswas, B. K., Roy Choudhury, T., et al, 2000, “Ground water Arsenic Contamination in
Bangladesh and West Bengal, India”, Environmental Health Perspective, 108, 388-397
18.Chadha D.K. and Sinha Roy S.P., “High Incidence of Arsenic in Groundwater in West Bengal”, CGWB,
Ministry of Water Resources, Faridabad, India, July 1999 Report.
19.Chakraborty, D., Samanta, G. et al, 1994, “Arsenic in Groundwater In Six Districts of West Bengal, India:
Biggest arsenic Calamity in the World”, Environ. Geochemistry and Health, 18, 5-15.
20. http://www.sos-arsenic.net/english/natural_origin/research_India.html (4 of 7)6/24/2004 4:24:03 PM
21. Rajiv Gandhi National Drinking Water Mission. http://rural.nic.in/book98-99/chapter7.pdff
22. Fazal, A., Kawachi, T., & Ichion, E., “Validity of the Latest Research Findings on Causes of Groundwater
Arsenic Contamination in Bangladesh”, International Water Resources Association, Water International, Vol 26,
No. 2, 380-389, June 2001.
23. Standard Methods for the Examination of Water and Wastewater, 1996, published jointly by American Public
Health Association [APHA], American Water Works Association and Water Pollution Control Federation
24. Basu, B. & Sil, S., “Arsenic Mapping for North 24 Parganas District of West Bengal- using GIS and Remote Sensing Technology”. www.gisdevelpment.net/application/environment/water/pdf/2004pdff
29-31 August, 2007 Paper-5
Arsenic contaminated aquifers: a study of the Ganga levee zones in Bihar, India
A.K.Ghosh1. S.K..Singh2, Nupur Bose3, S. Chaudhary4
1 Department of Environment and Water Management, A.N.College, Patna
2 Department of Environment and Water Management, A.N.College, Patna
3 Department of Geography, A.N.College, Patna, India
4 Department of Botany, T.M.Bhagalpur University, Bhgalpur, India
ABSTRACT-
'In Bihar Plains, ground water is the most important source of drinking and irrigation water. The purpose of this interdisciplinary study, undertaken along the levee of river Ganga in the Mid Ganga Plain, was to determine the existence and intensity of arsenic contamination in aquifers being tapped for direct and indirect ingestion of the properties of the region’s ground water, in the four districts of Bihar [India], i.e., Patna, Bhojpur, Vaishali and Bhagalpur. The methodology involved formulation of a protocol for arsenic detection in ground water, use of Field Test Kits for initial detection, obtaining GPS coordinates of arsenic hotspots for spatial analysis of the problem, and confirmatory testing of arsenic hot samples by U.V., and Atomic Absorption Spectrophotometry. Water samples of 28000 private and government owned hand pumps were tested. Many arsenic hotspots were detected in all the four districts, the coordinates of which were recorded by GPS. Arsenic contamination up to 1861 ppb. was found in the western district of Bhojpur, against the W.H.O. permissible limit of 10 ppb. The greatest frequency of contaminated hand pumps was noted in the eastern district of Bhagalpur. Sharp spatio-temporal variations of contamination levels were detected in this densely populated study belt.
Introduction
Arsenic is one of the less abundant metalloids forming the earth’s crust. Its important physico-chemical characteristic is that it is commonly concentrated in sulphide-bearing mineral deposits, pyrites and hydrous iron oxides1,2. Its presence in ground water sources is attributed to a number of natural and anthropogenic causes, based on its property of solubilizing in ground waters “depending on pH, redox conditions, and temperature and solution composition”3. Main sources of arsenic in aquifers include organic carbon or black shales, Holocene alluvial deposits, and volcanic sources4. Of particular relevance to this study, is the “strongly reducing, arsenic-rich aquifers”5 of the young alluvial sediments of the Mid Ganga Plains. Arsenic occurs widely in aquifers of deltaic sediments6, near zones of orogeny, and in deep sandy aquifer layers7 as fluvial deposits. It is introduced into the aquifer sediments in soluble state and gets adsorbed on iron-rich clastic grains and authigenic siderite concentrations. The adsorption process and its consequent desorption are stated to be controlled by microbial activity within the concerned aquifers8. Sediments containing 1 to 20 ppb. of arsenic can give rise to high dissolved arsenic of >50 ppb. by one or both of two possible causes – an increase of pH of over 8.5 or the onset of reductive iron dissolution3. Also, presence of solutes can also decrease or prevent the adsorbtion of arsenate and arsenite ions onto fine grained clays, like iron oxides8. Additional processes promoting high arsenic content in ground water are oxidation and dissolution of arsenian pyrite, Fe[As,S]2, and arsenopyrite [HN8], FeAsS9. Oxidation occurs either by infiltration of oxygenated ground waters10, or by lowering of ground water table into a stratigraphic zone of arsenic –rich sulphides11.
There are two main theories as to how arsenic is released into the groundwater -
Pyrite oxidation: In response to pumping, air or water with dissolved oxygen penetrates into the ground, leading to decomposition of the sulphide minerals and release of arsenic.
Oxyhydroxide reduction: Arsenic was naturally transported in the river systems of Bangladesh adsorbed onto fine-grained iron or manganese oxyhydroxides. These were deposited in flood plains and buried in the sedimentary column. Due to the strongly reducing conditions which developed in the sediments and groundwater of certain parts of Bangladesh the arsenic was released into groundwater. The release mechanism is still hotly debated but the second theory is thought to be the more likely explanation.
Our recent hydrochemical study of groundwater arsenic along transects from the foothill alluvium to the Indian Shield exposed in Mid Ganga Basin indicate that As concentrations are much higher in groundwater collected from the youngest alluvial terraces (~50% samples have 0.01 mg/L [WHO Maximum Contaminant Level] As, maximum 0.52 mg/L), than those associated with the shield (all 0.005 mg/L). Most (87%) of the As is present as As(III) 12.
Arsenic toxicity
Arsenic is highly toxic carcinogen (Category I) and also a mutagen / teratogen (harming foetus). Arsenic in ground water that is used for human consumption water, poses the greatest threat to public health13. Reliable data on exposure and health effects are rarely available, but it is clear that there are many countries in the world where arsenic in drinking water has been detected at concentrations greater than the WHO Guideline Value, 0.01 mg/L or the prevailing national standards. These include Argentina, Australia, Bangladesh, Chile, China, Hungary, Mexico, Peru, the United States of America and some countries in the South-East Asia Region. The arsenic crisis in Bangladesh has been described as one of the worst cases of mass poisoning in world history. Studies from West Bengal in India show that approximately 5 million persons are consuming groundwater containing arsenic exceeding 0.05 mg/L. Recent unconfirmed reports point to the presence of arsenic in Tamil Nadu and other states of India, implying industrial contamination of groundwater. In India, it is estimated that 220 000 of the 5 million exposed subjects are showing signs of arsenicosis.
W.H.O.14 has published Guidelines for Drinking Water Quality in which a contemporary value for an acceptable maximum level of Arsenic was set at 10 ug/l/ for safe water. National standards range from 7 ug/l in Australia to 50 ug/l in Vietnam, Cambodia and Bangladesh15.
Long-term oral exposure via drinking water can cause cancer of the skin16, lungs, urinary bladder, and kidneys. With long term exposure the first changes are usually seen in the skin pigments (indicator of arsenic poisoning), then hyperkeratosis. Symptoms of chronic arsenic poisoning can take five to 15 years to appear and are apparently influenced by nutrition and general health standards24. Increased risks of lung and bladder cancer and of skin lesions have been observed at arsenic concentrations of less than 0.05 mg / L of drinking water..
Statement of the problem-
Naturally occurring Arsenic, as a water quality issue in South Asia, began to attract international attention in the early decade of the nineties, when widespread chronic arsenic poisoning cases became apparent in Bangladesh and later in West Bengal, India17,18. Arsenic pollution in groundwater in this part of the subcontinent is a contentious issue. Investigations into the causation of arsenic pollution require a multidisciplinary approach19.
Later, the discovery of arseniferrous aquifers in Simaria-Ojhapatti village under Shahpur Block in Bhojpur, Bihar, located further upstream of the Bengal basin in 2003, raised apprehensions about the greater spatial spread of this dreaded contamination along the Ganga Valley.
In 2002, School of Environmental Studies, Jadavpur University, detected arsenic levels higher than the Bengal contamination readings. This has made it urgent for further detection of Arsenic infestation in the surrounding aquifers near River Ganga, within Bihar20,21. The study area of this research incorporates Patna District, the justification being its close proximity to Bhojpur District. The two districts are separated by the River Sone which confluences with the Ganga on the northern boundaries of both Bhojpur and Patna. Based on the hypothesis of previous random water analysis about possibilities of contamination in newer fluvial deposits,22, the study area of levee region was confined to an approximate belt of 10 kms. along the southern bank of River Ganga in the districts of Patna, Bhojpur and Bhagalpur; and along the northern bank in Vaishali district,
Methodology-
This research team formulated the Protocol, duly approved by Govt. of Bihar, Govt. of U.P., and UNICEF, for detection of arsenic over large areas. This Protocol is specifically intended for use by all those involved with arsenic detection in hand pumps using field test kits. The methodology incorporated in the Protocol has the following five significant components-
· All the public hand pumps of the study area were tested for Arsenic content through Field Test Kits by trained Staff.
· Each public hand pump tested was marked, with a unique Identification Code at the time of testing. The 13-digit code was derived from the Census 2001. This information identified the State, District, block and village, and finally the serial number of the Hand pump.
· Bihar Plains consist of sandy soils, where recent research has shown that presence of silica often masks the signal of arsenic from many chemicals11, thereby “creating a false optimum” of arsenic content lower than actually existing. Hence, 10% random verification of field test kit results was done through Atomic Absorption Spectroscopy.
· All field test results above 40mg/l were retested using AAS / UV Spectrophotometer23.
· Marking of hand pumps were done to inform the public of their status (safe/unsafe). The color codes applied were – Blue for FTK readings below 40 ppb.; yellow for FTK readings 40- 79 ppb.; and, Red for FTK readings of 80 ppb. and above.
· There is an increasing need to map the level of arsenic concentration, trends of arsenic flow and temporal changes occurring in its concentration levels. Recording the locations of Arsenic-affected hand pumps, using Global Positioning System (GPS) units24, was done, followed by mapping of the arsenic occurrences. The other references used were Block Maps, Topographical Maps.
· Use of field test kits as basic indicator of arsenic contamination -
The initial assessment of ground water arsenic contamination has been done by Field Test Kits designed by National Chemical Laboratory [NCL], Pune,and manufactured by Chem In corporation,Pune. As a reliable testing tool, FTK usage was previously discarded. However, during the Patna Study, the efficacy of FTK was proved by statistical comparison with AAS test results of the same water samples, in Sriram Institute of Industrial Research [SIIR], New Delhi. The SIIR Report on the efficacy of FTK has proved that it is a fast and economical, general indicator of arsenic contamination in water, provided the FTK users are trained technicians with a good idea of laboratory procedures.
F.T.K. Results -
Of the total of 27061 public hand pumps surveyed and sampled by Field Test Kits till date, 5757 hand pumps were contaminated with arsenic of over 10 ppb.. Taking into account the permissible limit of 10 ppb. set by W. H. O, the table below reveals massive contamination in Maner, Danapur, Bakhtiarpur, and Barh blocks [ Patna district]; Barhara and Shahpur blocks [Bhojpur district]; Kahalgaon, Pirpainti and Nathnagar blocks [Bhagalpur district]; and, Raghopur, Hajipur and Sahdai Buzurg[ Vaishali district].. These arsenic hotspots, forming the first group, have been found to be highly concentrated in the DIARA region. It would be not out of place to mention that there seems to be certain continuity in the occurrence of ground water arsenic, from Bhojpur district in the west into Bhgalpur to the east.
However deviations in the contiguity of the arsenic belt was noted in Sampatchak Block in Patna District and in Barhara and Shahpur blocks in Bhojour. Widespread occurrences of low level contaminations of around 50 ppb. in Sampatchak block, 5 km. away from the southern river bank,
In Patna, a fair presence of arsenic above 10 ppb., include Mokama, Sampatchak, Patna, Fatuha and Phulwari. The general areal extent of this contamination is in close proximity to the right bank of river Ganga, except in Sampatchak, where lower arsenic concentrations of 50 ppb. and less were spread over the entire block. While most of the blocks had a considerable number of “safe” or BDL marked hand pumps, the same is of limited proportion in Maner, where largest number of contaminated hand pumps were identified. Except Bihta, Naubatpur, Ghoswari and Daniawan all the blocks had contamination levels of above 10 ppb. to 50 ppb.
FTK Readings of water samples in worst
affected blocks,
Patna District
Sl.
No.
Name of
The Block
11 ppb. and above
1
Maner
38.04%
2
Danapur
26.87%
3
Sampatchak
16.58%
4
Barh
10.60%
5
Bakhtiarpur
14.47%
In Bhojpur, of the 5917 FTK tested samples, arsenic contamination at various levels, have been noted in 2806 samples. Udwantnagar has 100 contaminated sources against 67 “Nil” hand pumps. Barhara, Shahpur and Bihia have the maximium numbers of contaminated samples. The intensity of arsenic content can be best gauged by the. Fact thar Barhara , Shahapur and Bihia collectively spews arsenic rich water [> 50 ppb] from 1381 public hand pumps. Except Ara and Koilwar, the remaining 4 blocks have the largest share of arsenic contamination sources in the >50 ppb class. Conversely, Ara and Koilwar have the largest proportion of arsenic–free hand pumps. The total percentage of arsenic contaminated water samples fall within 3 groups- high contamination of over 50 % [Barhara and Udwantnagar]; moderate contamination of 30% to 50 % [Shahpur and Behea]; and low contaminated occurrences of below 30 % [Ara and Koilwar].
Overall, level of arsenic contamination in public hand pumps is both higher and more widespread than the situation in the neighboring Patna District
FTK Readings of water samples in worst
affected blocks,
Vaishali District
Sl.
No.
Name of the Block
11 ppb. and above
1
Raghopur
17.18
2
Hajipur
55.58
3
Bidupur
71.19
4
Sahdai Buzurg
68.09
5
Desri
68.42
In Vaishali, a total of 8080 water samples were tested by F.T.K.s, of which 18.73% were found to be contaminated. Raghopur was the only block that had 100% contaminated samples, although in comparison to other blocks, a large chunk of contaminated samples fell in the “below 40 ppb.” group. In Hajipur, 61.69% source samples tested arsenic – free, and only 119 [7.57%] of contaminated samples were of 40 ppb. and more. Bidupur, with 81.58% uncontaminated samples, had the largest share of arsenic “NIL” water source. But, a total of 102 [28.81% of contaminated samples] were in the 40 ppb+ range, making this block the most contaminated one. Sahdai Buzurg and Desri had 66.88% and 74.93% uncontaminated samples respectively.
FTK Readings of water samples in worst
affected blocks,
Bhojpur District
Sl.
No.
Name of the Block
11 ppb. and above
1
Barhara
55.35%
2
Shahpur
37.97%
3
Bihia
33.37%
4
Udwant-
Nagar
55.69%
5
Ara
15.23%
6
Koilwar
26.12%
In Bhagalpur District , 8075 hand pumps were subject to FTK tests, of which over 2500 sources tested positive. Kahalgaon and Pirpainti, had the largest number of contaminated drinking water hand pumps, followed by Nathnagar, Sabour and Sultanganj blocks.
FTK Readings of water samples in worst
affected blocks,
Bhagalpur District
Sl.
No.
Name of the Block
11 ppb. and above .*
1
Kahalgaon
48.50 %
2
Pirpainti
43.00%
3
Sabour
31%
4
Nathnagar
11.00%
5
Sultanganj
ANALYSIS OF AAS AND UV SPECTROPHOTOMETER RESULTS-
Out of 6101 samples collected in Patna, 457 samples were retested by AAS-HG method at Sriram Institute of Industrial Research, New Delhi. Of the 457 samples tested there, 390 samples were confirmed to have Arsenic content of over 10 ppb. Samples have tested as having more than 50 ppb. As. content. The highest As. content detected by AAS Method is 724 ppb. , this sample being collected from Naikatola Village, Maner block, in the hand pump located near the house of Mr. Pundev Singh.
In Danapur block the highest As. Level detected by AAS method is 450 ppb. at Kasimchak, from the hand pump located near the house of Mr. Sitaram Rai. The next highest reading of 409 ppb.in this block, is from the hand pump near the house of Mr. Laxman Rai of Harshamchak village, Danapur block.
In Bakhtiarpur, the highest arsenic level detected by AAS method is 553 ppb. in Ghiaspur Mahazi, outside the house of Ashok Mahto, followed by 538 ppb. in Kala Diara, outside the house of Faudar Paswan. In Barh, the highest arsenic level read by AAS is 484 ppb. in Malahi Banda, near the house of Balaj Mahto; and 441ppb. near the house of Mohan Mahto
In Bhojpur, 27.35% of the AAS-tested 457 samples fall within the 50-99 ppb. group, and 25.38% have arsenic content of between 11-49 ppb. Table-3 reveals a tapering down of the number of samples in the successive higher arsenic value groups. Uncontaminated samples were only 10.5%, while another 4.6%samples were within the permissible limit of below 10 ppb. All the four critical l blocks had large numbers of contaminations between 11-99 ppb.
The first list of AAS tested water samples from 656 villages in Barhara and Shahpur Blocks have been obtained. All the villages in this list have hand pumps with more than 10 ppb. Arsenic Content, interspersed with a lesser number of safe hand pumps [Table -15].
In the total of 656 AAS tested samples received till date, the highest values of 1861 and 1064 has been recorded in the houses of Krishna Pandey and Munna Pandey respectively, in village Pandey Tola, Sinha in Barhara. In Shahpur, the highest arsenic contamination of 598 ppb was recorded in the house of Baban Prasad at village Karnamepur.
90.05% the 586 contaminated samples are in the 11ppb. – 500ppb. level. Barhara has 91.07% and Shahpur has 88.75% in this contamination group. The two values of over 1000 ppb. merit serious attention to the Arsenic contamination problem in Barhara.
In Vaishali district, Highest number of contaminated samples was found in the 51-100 ppb. group [142 or 54.44%]. Another 77 FTK samples [28.51%] fell in the 11-50 ppb. group, while 36 samples [13.33%] were of 101-150 ppb. contamination levels. The remaining 15 samples tested more than 151 ppb.UV results of Bidupur show the largest contaminated samples in the 51-100 ppb. group among all the contamination groups of all the blocks. Desri’s water samples ranged between 11-101 – making it the least contaminated of the blocks surveyed
In Bhagalpur
SUMMARY OF AAS/UV SPECTROPHOTOMETER RESULTS
DISTRICT
No. of water sources with
more than
10 ppb. arsenic
Highest reading
Patna
392
724ppb
Bhojpur
656
1861 ppb.
Vaishali
270
360 ppb
Bhagalpur
1402
608 ppb.
Mapping of Arsenic Hotspots in Bihar -
GPS coordinates were obtained for all the hotspots. These were then imposed on the topographical sheets and the spatial parameter was assessed.
A total of 171 villages were surveyed in Patna.. Every block has some degree of arsenic contamination, Maner having more than 40 % of the water samples, and Danapur and Sampatchak with 30-40% of the samples testing positive. Less than 10 % of the samples from only Patna block tested positive. The remaining blocks had varying percentage values in the intermediate range between the two extremes. Sampatchak was the single block with diffuse spread of arsenic contaminated hand pumps - low intensity arsenic contamination exist in almost every village, and the highest reading went upto 50 ppb.
3 Clusters of hotspots were noted – Maner cluster, Danapur Cluster, Bakhtiarpur Cluster and Barh Cluster. All these hotspots were located in the DIARA or floodplains that are subject to annual inundation. Mokama and Pandarak had frequent occurrences of 50 ppb. too. Gradual decreases in the number of highest readings were noted from west to east. Also, arsenic concentrations tapered down towards south, supporting the hypothesis of arsenopyrite oxidation of Holocene sedimentary deposits3, 10. This oxidation has been attributed to excessive withdrawal of ground water by the inhabitants, both for domestic purpose and agricultural use.As one moved away from the riverbank, the frequency of arsenic contaminated sources decreased. Tests were also extended southward along the right bank of river Sone in order to seek spread of contamination. However, all the samples collected from the Sone bank further south of its confluence with the Ganga, tested negative. It can be safely concluded that the menace of Arsenic in ground water exists in Patna district, parallel to the Ganga riverbank, in a broken belt from Maner in the west to Mokama in the east. These findings need further regular monitoring to detect future changes in its extent and intensity.
As per AAS confirmatory test results, Arsenic contaminated sources were found to be greatest in Maner and Danapur blocks and were interpretated through isoline mapping of northwest Patna. The map obtained thus, revealed four concentrations of high arsenic levels, around which decreasing iso-values were interpolated. The resultant pattern is highly indicative of the presence of arsenic rich rock layer within or very close to the major aquifer [[major aquifer depth- 60 to 110 feet] in this area, from where maximum water is withdrawn. This finding needs to be further assessed by possible digging of boreholes, for geochemical analysis, in the peak value spots identified in the map. The space between the Maner and Danapur Clusters are uninhabited, but it falls within the zone of potential arseniferrous aquifers. The peculiarity of this metalloid in Patna is that it is non-existent in open wells, and is absent on, and, beyond the older alluvium of the southern levee.
Choropleth maps were prepared on the basis of FTK data to identify the arsenic hotspots in Bhojpur District. GPS readings were obtained from all the known arsenic affected villages. Barhar and Shahpur blocks had the highest frequency of arsenic contaminated handpumps in almost all the villages.. Behea is contaminated in its north-easterm parts, while Udwantnagar is heavily contaminated in the small area covered. Ara and Koliwar reveal diffuse contamination, though of a lesser intensity than the remaining blocks.
The unpredictable nature of arsenic levels was also revealed. Some villages with more than 75% contaminated hand pumps are located along the southern boundary of the 10 km. belt in Barhara, and Udwantnagar, giving credence to the possibility of arsenic contamination further into the district interiors.
Unlike the Patna contaminations, where there was a tapering down of arsenic content in water away from the Ganga Bank, Bhojpur has widespread arsenic occurrences, that also occur at all aquifer levels accessed by the local population. Repeated high arsenic contamination in Udwantnagar forced the Project Investigator to test water samples of Chhotka Sasaram Village adjacent to the southern boundary of the 10 km. belt, and arsenic contamination was found to be very high. Some of the demarcated villages have been abandoned, and have not been subjected to FTK tests.
North of the Ganga River, arsenic hotspots are more frequent 4 – 5 kms. away from the river bank. Here in Vaishali, riverside contamination with over 50 ppb readings was confined to 3 settlements only. A comparatively larger number of contaminated villages are noted nearer the Gandak River in Hajipur Block.
Although much of Raghopur were covered due to annual inundation, all the samples were contaminated. All villages drinking water sources tested here had a number of above 50 ppb contaminated drinking water sources. There was a concentration of > 40 ppb water sources in the narrow land on the north-eastern part of Raghopur. Bidupur had the minimum contamination [18.34%samples contaminated]. The areal spread of contamination is less than in Hajipur and is more on the northern part of this block. Dot clusters again become frequent in Desri and Sahdai Buzurg Blocks. Readings of over 40 ppb are noted along the northern boundary of the study area, suggesting a further northward spread of arsenic contamination.
Maps also revealed the intensity of contamination levels. Raghopur block had no ‘NIL’ samples, and a large percent of low contamination of below 10 ppb. In all the other blocks, contaminations of 11-39 ppb. are significant.
The FTK data maps of Patna and Bhojpur supported the hypothesis of this research team that the areal spread of ground water arsenic contamination bears some correlation to the occurrence of iron-rich newer fluvial deposits in Bihar; hence its frequency nearer the banks of the Ganga. Vaishali maps reveal a different pattern. There are arsenic occurrences in all the villages surveyed in Raghopur island in the south with a few corresponding occurrences hotspots along the northern banks of the river. Immediately to the north of the bank area, are a series of villages with “NIL” FTK readings. Beyond this, further north is a near-contiguous arsenic contamination belt, with intervening non-surveyed villages, that extends roughly parallel to the river bank in an east-west direction. The belt can be traced from Hajipur in the east to Sahdai Buzurg in the west. It is indicative of serious arsenic contamination beyond the arbitrary 10 km. study belt in northern Bihar. The spatial pattern once again highlights the abruptness and unique spread of arsenic in each district of Bihar and calls for immediate hydro-geological analysis.
The flood-prone “diara” areas of Bhagalpur revealed a spatial pattern similar to that of Patna district, with the number of occurrences decreasing away from the river bank. However, Bhagalpur’s contamination extended to even open-wells in Nathnagar . Continuity of hotspots in Kahalgaon and Pirpainti, gives credence to the fact that arsenic mobilization was advancing upstream from the adjacent Bengal Basin along the eastern boundary of this district.
Recommendations-
• A comprehensive study for arsenic contamination in ground water is urgently required all along the banks of Ganga.
• All hand pumps confirmed as having more than 50 ppb. Arsenic content be capped immediately.
• Efforts should be made also to minimize the intake of water having arsenic content of 10 ppb to 50 ppb.
• Gradual, planned reduction of local permissible limit of 50 ppb. to 10 ppb., to avoid long-term assimilation and accumulation of arsenic among the undernourished child and young population
• Identification ,usage and maintenance of arsenic-free aquifers may be carried out in the affected villages identified by this study on priority basis.
• Provisions for alternate safe sources of drinking water, such as piped water, can be implemented wherever possible.
• Intensive awareness campaign should be initiated in arsenic affected villages, educating them about the scourge. Services of nutritional experts can be harnessed, who can identify nutrition-rich agricultural produce and advice the villagers on how to increase the intake of proteins, vitamins and minerals through increased consumption of such local farm products.
• Supply of low-cost, community-based arsenic filters be provided to the affected villages
• Usage of dug wells, with proper water treatment, can be resumed, as the wells of the surveyed area have not tested positive for arsenic contamination till date.
• In all the mitigation work to be adopted, community participation is a basic prerequisite, as it will aid the stakeholders in effective management of arsenic contaminated drinking water sources
• Clinical investigation be initiated in affected villages by a team of doctors
• There is an urgent need for fully-equipped health centres in the arsenic identified areas.
• Further research through bioremediation by “arsenic munchers”[microbes and ferns] should be encouraged, on the principle that nature’s problems can be overwhelmed by identifying solutions existing within nature itself.
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