ARSENIC CONTAMINATION OF GROUND WATER IN INDIA :---->
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STUDIES CARRIED BY NATIONAL RURAL DRINKING WATER PROGRAMME (NRDWP)---2018, PUBLIC HEALTH ENGINEERING DEPARTMENT (PHED) DATA--2016 , LATEST REPORT OF THE CENTRAL GROUND WATER BOARD (CGWB)--2019 ALL SAYS THAT ARSENIC CONTAMINATION OF GROUND WATER IS ONE OF THE CRIPPLING ISSUES IN THE DRINKING WATER SCENARIO OF INDIA BUT THE RESULT OF ARSENIC(As) CONTAMINATION VARIES.
THE STATES ALONG THE GANAGA-BRAHMAPUTRA-MEGHANA RIVER BASINS SUCH AS UTTAR PRADESH, BIHAR, JHARKHAND, WEST BENGAL AND ASSAM ARE WORST AFFECTED BY THIS HUMAN-AMPLIFIED GEOGENIC OCCURANCE. DUE TO LACK OF TESTING AND STUDIES WE HAVE UNDERESTIMATED DATA BUT DISTRICT AFFECTED BY "As" IS GROWING, THE INCONSISTENT DATA CAN BE TERMED AS "MISSED DISTRKICT".
RANKWISE GEOGRAPHICAL DISTRIBUTION OF ARSENIC AFFECTED AREAS IN INDIA ARE :
RANK 1: ASSAM--17 DISTRICT AFFECTED
RANK 2 : WEST BENGAL --
RANK 3 : BIHAR
RANK 4 : U.P.
RANK 5 : JHARKHAND
RANK 6: CHHATTISGARH
OTHERS ARE : KARNATAKA, PUNJAB AND HARYANA
ACCORDING TO NRDWP-2018 REPORT, 46 DISTRICT HAS ARSENIC LEVEL LIES BETWEEN 0.01-0.05mg/L AND 17 DISTRICTS WHERE ARSENIC LEVEL IS BEYOND 0.05mg/L. THESE DISTRICTS HAVE ARSENIC LEVEL ABOVE THE BUREAU OF INDIAN STANDARD (BIS) PERMISSIBLE LIMIT FOR SAFE DRINKING WATER IS BELOW 0.01mg/L.
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WHY WE CONCERN ABOUT ARSENIC CONTAMINATION OF GROUND WATER ?
ARSENIC CONTAMINATED GROUND WATER IS USED FOR DRINKING, IRRIGATION OF AGRICULTURAL FIELDS TO GROW DIFFERENT FOOD CROPS AND VEGETABLES. THE ENTRY OF ARSENIC IN FOOD CHAIN LEADS TO DIFFUSED CONTAMINATION, POSSIBILITIES OF BIO-MAGNIFICATION IN FOOD PRODUCTS. THE RICE, WHEAT, VEGETABLES, FEEDER CROPS OF LIVESTOCKS. CATTLE PRODUCTS CONTAMINATION ALONG WITH DRINKING WATER.
ARSENIC (As) BELONGS TO THE SAME GROUP AS NITROGEN, PHOSPHOSROUS IN THE PERIODIC TABLE MEANS ARSENIC HAS STRUCTURAL SIMILARITY AND CELLULAR METTALOID TRANSPORT SYSTEM LIKE PHOSPHATE CALLED ARSENATE. THUS, THE LIVING ORGANISM LIKE PLANTS AND ANIMALS TAKES UP ARSENATE ALONG WITH PHOSPAHATE (3-OH group) .
ADVESRE IMPACT ON HUMAN HEALTH OF ARSENIC CONTMINATIONS ARE : SINCE, As is TOXIC, POSIONIOUS AND CARCINOGENIC AND ITS ACCUMULATION IN THE BODY MORE THE PERMISSIBLE LIMITS THEN CAUSE ARSENICOSIS. IT LEADS TO TO ADVERSE IMPACT ON HEALTH BY INHIBITING ESSENTIAL ENZYMES, WHICH ULTIMATELY LEADS TO DEATH FROM MULTI-ORGAN SYSTEM FAILURE. IT LEADS TO SKIN DAMAGES, SKIN CANCERS, DISEASES OF VASCULAR SYSTEM, DIABETES, ADVERSE REPRODUCTIVE OUTCOMES.
CAUSES OF HIGH ARSENIC IN GANGA-BRHAMAPUTRA-MEGHANA BASIN :---->
GENERALLY THERE ARE TWO MECHANISM TO BUILD ARSENIC IN SOIL AND GROUND WATERS . 1) UNDER HIGH pH AND OXIDISING CONDITIONS (pH >> 8.5) AND 2) UNDER REDUCING ACUIFERS CONDITIONS , HERE CHEMICAL FORM ARSENIC DEPENDS ON REDOX POTENTIAL.
IN INDIA THE NORTHERN PLAINS ALLUVIAL SOIL AREAS GROUND WATER IS BEING CONTAMINATED WITH ARSENIC DUE TO HIMALAYAS CONTAINS ARSENIC RICH ROCKS SUCH AS PYRITES (FeS2) WHICH UNDERGOES EXCESSIVE WEATHERING AND EROSION . THE ERODED MATERIAL SUCH AS FINE SILT AND CLAY CARRIES BY RIVER SYSTEM AND FINALLY DEPOSITED IN THE NORTHERN PLAINS AND DELATS. THUS THE ALLUVIAL SOILS IS RICH IN ARSENIC, IT INFILTERATES WHEN GRONDWATER MOVEMENT IS SLOW IN NORTHERN PLAINS. HERE ORGAINIC MATTER GROWS, MICROBES BIND CARBON AND ARSENIC AND RELEASES THE ARSENIC IN GROUND WATERS.
AGE OF THE AQUIFERS SEDIMENTS ALSO HELPS TO PREDICT THE OCCURENCE OF ARSENIC CONTAMINATED GROUND WATERS. THERE ARE TWO TYPES OF AQUIFERS .
1) YOUNG AQUIFERS (HOLOCENE--10,000 YEARS TO PRESENT)-- MUCH YOUNGER, RECENT ALLUVIUM DEPOSITS, HAS YOUNG FRESH ORGANIC MATTER, FINE-GRAINED TEXTURE OF SEDIMENTS , AMORPHOUS MINERAL PHASE, OFTEN REDUCING CONDITIONS, ELEVATED ARSENIC LEVELS.
2) OLDER AQUIFER (PLEISTOCENE -- 1.8MILLION YEARS TO 10,000 YEARS AGO)--HAS LESS ORGANIC MATTER, COARSE GRAINED AND CRYSTALLINE PHASE, OXIC CONDITION, LOW ARSENIC CONCENTRATION.
FACTORS INFLUENCING THE ARSENIC (As) CONTAMINATIONS ARE : (SUMMERY)
1) LOW LYING AREAS SUCH AS ALLUVIAL PLAINS AND DELTAIC PLAINS
2) REDUCING GROUND WATERS (REDOX POTENTIAL)
3) ORGANIC RICH-SEDIMENTS
4) YOUNG SEDIMENTS
5) VOLCANIC ORES
6) AREAS AFFECTED BY LARGE SCALE PUMPING
7) MINING ACTIVITIES
8) INDUSTRIAL ACTIVITIES
THUS BOTH NATURAL AND HUMAN INDUCED ARSENIC CONTAMINATION IS INCREASING .
MEASURES/ SOLUTION : FOR ARSENIC MANAGEMENT ARE :
1) ARSENIC REMOVAL UNITS THROUGH HAEMATITE GRANULES SEDIMENTATION )
2) USES OF SURFACE WATER SOURCES
3) EXPLORING AND HARNESSING ALTERNATE ARSENIC FREE AQUIFERS.
4) ADOPTING RAINWATER HARVESTING AND WATERSHED MANAGEMENT PRACTICES RAISE THE WATER TABLE.
