Arsenic contamination of groundwater

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Main article: Water pollution

Arsenic contamination of groundwater has occurred in various parts of the world, most notably the Ganges Delta of Bangladesh and West Bengal, India, causing serious arsenic poisoning among large numbers of people. It is a natural occurring high concentration of arsenic in deeper levels of groundwater, which became a high-profile problem in recent years due to the use of deep tubewells for water supply in the Ganges Delta .

Parts of Thailand, Taiwan, Argentina, Chile and China have also been affected.[1] Approximately 20 incidents of groundwater arsenic contamination have been reported from all over the world.[2] Of these, four major incidents were in Asia.[3] Roger Smith, Professor of Pharmacology and Toxicology Emeritus, Dartmouth Medical School, has confirmed that natural arsenic contamination of drinking water has also been a problem in wells in New Hampshire.[citation needed]

Contents

[edit] Bangladesh and West Bengal

The story of the arsenic contamination of the groundwater in Bangladesh is a tragic one. Diarrheal diseases have long plagued the developing world as a major cause of death, especially in children. Prior to the 1970's, Bangladesh had one of the highest infant mortality rates in the world. Ineffective water purification and sewage systems as well as periodic monsoons and flooding exacerbated these problems. As a solution, UNICEF and the World Bank advocated the use of wells to tap into deeper groundwater for a quick and inexpensive solution. Millions of wells were constructed, infant mortality and diarrheal illness were reduced in half. However with over 11 million wells constructed, it has been found over the last two decades that 40% of these wells are contaminated with arsenic. Arsenic is a carcinogen which causes many cancers including skin, lung, and bladder as well as cardiovascular disease. [4]

In the Ganges Delta, the affected wells are typically more than 20 m and less than 100 m deep. Groundwater closer to the surface typically has spent a shorter time in the ground, and so has not absorbed a high concentration of arsenic; water deeper than 100 m is exposed to much older sediments which have already been depleted of arsenic.[1][5]

Dipankar Chakraborti from West Bengal brought the crisis to international attention in a research paper published in The Analyst in 1995 and reported on by David Bradley (The Guardian, January 5, 1995, "Drinking the water of death"). [6] [7] Beginning his investigation in West Bengal in 1988, he eventually published, in 2000, the results of a study conducted in Bangladesh which involved the analysis of thousands of water samples and hair, nail and urine samples. They found 900 villages with arsenic above the government limit. Chakraborti described this as "only the tip of the iceberg."[1][3]

Chakraborti has criticized aid agencies, saying that they denied the problem during the 1990s while millions more tube wells were sunk, and later hired foreign experts who recommended treatment plants which were not appropriate to the conditions, regularly breaking down or not removing the arsenic.[8]

Chakraborti says that the arsenic situation in Bangladesh and West Bengal is due to negligence. However, he also says that in West Bengal, water is mostly supplied from rivers. Groundwater comes from deep tubewells, which are few in the state. So the risk of arsenic patients in West Bengal is comparatively less. [9]

According to the World Health Organisation, “In Bangladesh, West Bengal (India) and some other areas, most drinking-water used to be collected from open dug wells and ponds with little or no arsenic, but with contaminated water transmitting diseases such as diarrhoea, dysentery, typhoid, cholera and hepatitis. Programmes to provide ‘safe’ drinking-water over the past 30 years have helped to control these diseases, but in some areas they have had the unexpected side-effect of exposing the population to another health problem - arsenic.” [10] WHO has defined the area under threat: Seven of 16 districts of West Bengal have been reported to have ground water arsenic concentrations above 0.05 mg/L; the total population in these seven districts is over 34 million and it has been estimated that the population actually using arsenic-rich water is more than 1 million (above 0.05 mg/L) and is 1.3 million (above 0.01 mg/L). According to a British Geological Survey study in 1998 on shallow tube-wells in 61 of the 64 districts in Bangladesh, 46% of the samples were above 0.010 mg/L and 27% were above 0.050 mg/L. When combined with the estimated 1999 population, it was estimated that the number of people exposed to arsenic concentrations above 0.05 mg/l is 28-35 million and the number of those exposed to more than 0.01 mg/l is 46-57 million (BGS, 2000). [10]

The solution according to Chakraborti, “By using surface water and instituting effective withdrawal regulation. West Bengal and Bangladesh are flooded with surface water. We should first regulate proper watershed management. Treat and use available surface water, rain-water and others. The way we're doing at present is not advisable.[9]

[edit] Water purification solutions

Chakraborti claims that arsenic removal plants (ARPs) installed in Bangladesh by UNDP and WHO were a colossal waste of funds due to breakdowns, inconvenient placements and lack of quality control.[9]

A simpler and less expensive form of arsenic removal is known as the Sono arsenic filter, using 3 pitchers containing cast iron turnings and sand in the first pitcher, and wood charcoal and sand in the second.[11] Plastic buckets can also be used.[12] It is claimed that thousands of these systems are in use, and that they can last for years, while avoiding the toxic waste disposal problem inherent to conventional arsenic removal plants.

[edit] Dietary intake

Researchers from Bangladesh and the United Kingdom have recently claimed that dietary intake of arsenic adds a significant amount to total intake, where contaminated water is used for irrigation.[13]

[edit] See also

[edit] Notes and references

  1. ^ a b c The UNESCO Courier, Bangladesh's arsenic poisoning: who is to blame?
  2. ^ Mukherjee A., Sengupta M. K., Hossain M. A. (2006). "Arsenic contamination in groundwater: A global perspective with emphasis on the Asian scenario". Journal of Health Population and Nutrition 24 (2): 142-163. 
  3. ^ a b Chowdhury U. K., Biswas B. K., Chowdhury T. R. (2000). "Groundwater arsenic contamination in Bangladesh and West Bengal, India". Enviromental Health Perspectives 108 (4): 393-397. 
  4. ^ Ibrahim, A., Wilson, R., Chronic Arsenic Poisoning: History, Study and Remediation ( accessed 11 Feb 2007.
  5. ^ Singh A. K. (2006). "Chemistry of arsenic in groundwater of Ganges-Brahmaputra river basin". Current Science 91 (5): 599-606. 
  6. ^ Amit Chatterjee, Dipankar Das, Badal K. Mandal, Tarit Roy Chowdhury, Gautam Samanta and Dipankar Chakraborti (1995). "Arsenic in ground water in six districts of West Bengal, India: the biggest arsenic calamity in the world. Part I. Arsenic species in drinking water and urine of the affected people". Analyst 120: 643-651. DOI:10.1039/AN9952000643. 
  7. ^ Dipankar Das, Amit Chatterjee, Badal K. Mandal, Gautam Samanta, Dipankar Chakraborti and Bhabatosh Chanda (1995). "Arsenic in ground water in six districts of West Bengal, India: the biggest arsenic calamity in the world. Part 2. Arsenic concentration in drinking water, hair, nails, urine, skin-scale and liver tissue (biopsy) of the affected people". Analyst 120: 917-925. DOI:10.1039/AN9952000917. 
  8. ^ New Scientist, Interview: Drinking at the west's toxic well31 May 2006.
  9. ^ a b c The Times of India, 'Use surface water. Stop digging', interview, 26 Sep, 2004.
  10. ^ a b World Health Organization, Arsenic in Drinking Water, accessed 5 Feb 2007.
  11. ^ Evaluation of Performance of Sono 3-Kolshi Filter for Arsenic Removal from Groundwater Using Zero Valent Iron Through Laboratory and Field StudiesPDF (272 KiB)
  12. ^ SONO® ARSENIC FILTER FROM BANGLADESH - 1PDF (102 KiB) - pictures with descriptions.
  13. ^ Toxic rice harvested in southwestern Bangladesh, 13 July 2006, SciDev.Net; and Williams et al, 2006, Increase in Rice Grain Arsenic for Regions of Bangladesh Irrigating Paddies with Elevated Arsenic in Groundwaters, Environ. Sci. Technol.

http://www.pcrwr.gov.pk/Arsenic_CP.htm

  • Smedley PL, Kinniburgh DG (2002). "A review of the source, behaviour and distribution of arsenic in natural waters". Applied Geochemistry 17 (5): 517-568. DOI:10.1016/S0883-2927(02)00018-5. 
  • Nickson RT, McArthur JM, Ravenscroft P (2000). "Mechanism of arsenic release to groundwater, Bangladesh and West Bengal". Applied Geochemistry 15 (4): 403-413. DOI:10.1016/S0883-2927(99)00086-4. 
  • Korte N. E., Fernando Q. (1991). "A Review of Arsenic(III) in Groundwater". Critical Reviews in Enviromental Control 21 (1): 1-39. 
  • Smith AH, Lingas EO, Rahman M (2000). "Contamination of drinking-water by arsenic in Bangladesh: a public health emergency". Bulletin of the World Health Organization 78 (9): 1093-1103. 
  • Harvey CF, Swartz CH, Badruzzaman ABM (2002). "Arsenic mobility and groundwater extraction in Bangladesh". Science 298 (5598): 1602-1606. DOI:10.1126/science.1076978. 
  • Hossain MF (2006). "Arsenic contamination in Bangladesh - An overview". Agriculture Ecosystem & Enviroment 113 (1-4): 1-16. DOI:10.1016/j.agee.2005.08.034. 

[edit] External links

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