Thursday, September 12, 2013
Massive groundwater pumping in Asia may poison millions
The study, published by experts from Switzerland, the US and Vietnam, examined changing groundwater flow over one decade in Vietnam’s capital, Hanoi.
Hanoi is expanding rapidly, as is water demand. Pumping for municipal water supplies doubled between 2000 and 2010, to around 240 million gallons daily. In the city, water is filtered and treated, but in areas just a few kilometres outside, near the Red River, many households use private untreated wells.
In the past, higher water levels in the aquifer (underground layer of water-bearing rock, sand or silt) meant water from these wells was generally safe. But as more groundwater has been pumped, water from arsenic-rich sediments is increasingly intruding into the previously uncontaminated aquifer.
Arsenic, one of the most common inorganic contaminants found in drinking water worldwide, can be highly toxic to humans. Even in low concentrations arsenic can damage health if ingested over long periods. It is associated with cancer of the skin, lungs, bladder and kidneys.
At some sites in Vietnam investigated for the study, arsenic concentrations were up to 50 times higher than the internationally recommended limit of 10 micrograms of arsenic per litre....
A bridge over the Red River in Hanoi, shot by Luigi Guarino, Wikimedia Commons, under the Creative Commons Attribution 2.0 Generic license