standard Arsenic: a deep environmental problem

ResearchBlogging.orgOn this blog we have explored research on arsenic contaminated drinking water in Bangladesh in an interview with Dr Manzurul Hassan who was a visiting researcher in IHRR last year, and is a colleague of Prof Peter Atkins based in the Dept of Geography in Durham University who also works on the arsenic problem.  Arsenic poisoning in Bangladesh is without a doubt one of the worst environmental problems in the world today affecting the health of millions of people in Bangladesh and other countries in Southeast Asia.

A paper published last month in the Proceedings of the National Academy of Sciences focuses on the problem of arsenic poisoning in Vietnam where drilling deep tube wells for arsenic-safe water may not necessarily resolve the problem, but could actually worsen the situation.  The study demonstrates that statistical modelling can be used to see how deep arsenic lies within the Earth when drilling for drinking water.  But it also shows that arsenic located in upper layers of sediment could leach down into the deep aquifers.

To avoid contamination, wells in the Bengal Basin can be drilled into deep layers that were oxidized during the last ice age, in which the water is free of arsenic, says Dr Michael Berg [co-author on the study] . These aquifers were created during the Pleistocene epoch, between 12,000 and 2.5 million years ago, and lack the organic carbon that is needed for arsenic to leach into water.

But if people in the Bengal Basin continue to exploit their water supplies at the current rates, arsenic-laden water from the upper layers may find its way into Pleistocene aquifers, the study suggests. ‘Arsenic sinks to new depths.’ Nature News

According to Hassan, deep acquirers were questioned by the Bangladeshi government years ago as to whether or not they would provide a lasting  solution to arsenic contaminated drinking water:

In 2005 there was an assessment of the options and the installation of deep tube wells was banned by the government until it could be determined whether the arsenic-safe deep aquifer was protected by an impermeable layer.  If the deep aquifer is ever contaminated with severe levels of arsenic, there will be no option for arsenic-safe drinking water. Interview with Dr Manzurul Hassan. IHRR Blog

Other means of providing arsenic-safe drinking water have also been looked at by government including rain water harvesting, but it seems that (and this has been said before by others including science writer David Bradley) that arsenic poisoning is not solely a scientific or technical problem, but a highly political and social problem.  Even if a sophisticated technology is developed or is available now to filter or treat arsenic contaminated water, there is still the problem of making it available to some of the poorest countries in the world who experience these problems on a daily basis.  Are there low-tech methods for preventing arsenic poisoning through drinking water?  Like any environmental problem that affects human health, people need policy that can allocate resources, both scientific and social, effectively before any solution is found.  Unfortunately, science and technology alone are not enough, but more importantly researchers and government need to understand why in order to act intelligently instead of continuing to make mistakes of the past.

Vaidyanathan, G. (2011). Arsenic sinks to new depths Nature DOI: 10.1038/news.2011.20

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