TUESDAY, OCTOBER 26, 2004
Poisoned Waters
Arsenic pollution is a threat to life and livelihood in the Ganga, Meghna and Brahmaputra (GMB) basins. Widespread presence of cancer among those living in this region has been attributed to arsenic contamination of groundwater. Dipankar Chakraborti, director of Jadavpur University School of Environmental Studies, tells Surojit Mahalanobis that regulation of tubewells and better water management offer a way out:
Where all have you detected arsenic in aquifers?
It is found in Bihar, in tubewells in Purantola, Newtola, Dihal Reketola and Badaltola villages in Patna district.
How does arsenic accumulate in groundwater?
There are various theories that explain the phenomenon - such as oxidation, reducing condition of aquifers, organic inflow. Arsenic also leaches into aquifers due to microbial activity. It has been there for thousands of years. Some believe arsenic is sourced from the Himalayas, Tibet plateau and Kunlun mountain range in China etc. It's not an anthropogenic source but started soon after man began using groundwater.
How do you trace areas contaminated with arsenic?
Through research carried out at several locales. We found that the flood plains of Ganga-Meghna-Brahmaputra (GMB) in Uttar Pradesh, Bihar, Jharkhand, West Bengal, Bangladesh and Assam are arsenic-affected. Arsenic contamination is possible in any place in this over 5 lakh sq km area. It affects about 450 million people. However, that doesn't mean the entire population in this belt is affected. But the risk is always there; which tubewell will be affected depends on many factors.
How serious is the risk to the people living in this area?
A WHO report predicts that within a few years one in 10 adult deaths in south Bangladesh could be due to cancers triggered by arsenic. The problem with Bangladeshi patients is that most of them are poverty-stricken. With better nutritional care, you can fight the arsenic that gets into the body through water and food. 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 poisoning in West Bengal is comparatively less. Kolkatans can resist arsenic toxicity by cultivating nutritive food habits. But, we still have many arsenic patients in Kolkata.
Recently in the Royal Society's 'Journal of Environmental Monitoring' you blamed human behaviour for arsenic contamination. Geological surveys in the US and the UK claim it is natural. I haven't said it is man-made. I said the source of arsenic is geogenic but due to extensive use of huge groundwater we are exposed to arsenic. Arsenic is always present in aquifer sediment. Groundwater extraction leads to pyrite oxidation which pollutes the water that is taken out.
Are there any ways to prevent it?
The way out is to use surface water and institute effective withdrawal regulation. West Bengal and Bangladesh have sufficient surface water. We should first have proper watershed management. Treat and use available surface water - rainwater and other similar sources of water. Arsenic pollution in Bangladesh and West Bengal is due to misguided state policies. We should be careful not to follow the same policies in Bihar, Uttar Pradesh, Jharkhand and Assam.
You have claimed that the arsenic removal plants (ARPs) installed in deep tubewells under the UNDP and WHO programmes are a failure. Why?
Since 2000, we have been questioning the efficacy of the ARPs installed in West Bengal and Bangladesh. In West Bengal, the government spent crores of rupees at Murshidabad, North 24-Parganas and in Kolsur in Deganga delta. Of the total of 182 ARPs installed, 63 were found defunct, many were installed at inconvenient places and the success rate was only 11%. Besides, most ARPs didn't have effec-tive quality control provision either.
Scientists with the Central Ground Water Authority claim that arsenic can be easily leached out at treatment plants. Theoretically, yes, but ask yourself. Why did ARPs fail? In India and Bangladesh an advanced technology may not work unless politicians want it honestly. Given the size of the contaminated area, how many water treatment plants can you instal? Can you take them to remote villages? If you do, at what cost?
How do we combat the arsenic threat?
Build awareness among people and create alternate water sources. People must know when to discard a tubewell or borewell. The government must be ready to exploit surface water properly. Stop digging tubewells and regulate borewells. Test tubewells for arsenic every three to six months. Proper watershed management must be in place. Encourage use of treated water from rivers, wetlands and ox-bow lakes which are in plenty here. Institute indigenous system of filtering mined water, do rainwater harvesting, use lime and other disinfectants to protect stored water from bacteria and chemicals, educate people to use night-long settled water as we have been doing traditionally. Educate villagers about the danger of arsenic toxicity and benefits of eating seasonal fruits and vegetables. Keep the wells bacteria free. A healthy body can fend off arsenic.
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