Arsenic in groundwater- West Bengal

Arsenic in groundwater is becoming a difficult problem in many parts of the country. This problem is acute in West Bengal and is spreading to other parts of the country with awareness to quality of drinking water is growing.

Take the case of West Bengal. In 1959, minor-irrigation projects were started in the state in collaboration with the Exploratory Tube-well Organization of the Union government. As per the 2001 census, there are about 5, 50,000- tube wells in the state; 64 per cent of 54640 square kilometres of cultivable land in the state is under irrigation — by tube wells that tap groundwater. Irrigated farming has supported millions of people, but that has a horrible spin off: arsenic levels have risen in the shallow aquifers of West Bengal. But how did irrigation lead to such pollution? The water used for farming had high levels of arsenic and the arsenic accumulated in the roots of rice plants — its levels are reported to be as high as 169 parts per million. When these roots were ploughed back into the soil, during subsequent irrigation arsenic released from roots found their way to the shallow aquifers. The paddy stem, leaves, the grain and the husk have arsenic concentration far above the level prescribed by the World Health Organization. All these parts are consumed by man and animals!! Now even the kitchen vegetables also registered arsenic levels above the prescribed limit.  Now arsenic has entered the food chain in West Bengal. This development began a couple of decades ago and is continuing unabated. Groundwater irrigation was envisaged as a panacea for food shortage, it has polluted drinking water and killed many. The Water Investigation and Development Department, which oversees water quality has completely ignored the problem. And preliminary studies indicate that the rot is spreading to parts of Northeast India.

What can be done?

            There are several technologies to remove arsenic from drinking water  — some of these are reverse osmosis, precipitation and flocculation and solar oxidation. But these are costly and unfeasible to implement and practice by the rural population.

            Providing safe drinking water to rural communities is an integrated effort, which requires engaging skills of hydrologists, engineers, medical experts and non-governmental organisations. These specialists should be involved in identifying the areas affected by arsenic and in collecting data about the extent of the problem. Once this is done, the affected basins should be mapped and permanent observation basins identified. This will not only create a good data bank on individual basins but also trained personnel who can be consulted to oversee the problem in future.

            Tackling the arsenic problem also requires changing people’s mindsets. Since the chemical does not affect humans overnight, there is always a tendency to procrastinate on solutions. The state groundwater organisations and public health departments should take the help pf grassroots bodies in raising people’s awareness in the affected areas.   

Over the long-term

But these are all short-term solutions. There is no viable long-term panacea except harnessing surface water to mitigate both drinking water and arsenic problems. The large volumes of surface water that gets discharged into the seas every year can easily be used for these purposes. For example, the government of Meghalaya has created an excellent lake to store surface water; this reservoir supplies water to communities in Shillong. Facilities to create such water bodies exist in all the northeast states. Besides, the entire region has a good water drainage system; interlinking them scientifically could provide water for irrigation as well as for drinking.  The microbial problem associated with surface water sources can easily be tackled compared to removal of arsenic in groundwater. Of course, interlinking has political problems which can be solved. This is much easier than saving millions from arsenic related diseases. Making the project completely transparent would take care of the problem to a great extent: the data generated should be made available in the public domain. Academic institutions and the state public works departments should collaborate in the endeavour.