New method developed to map arsenic affected areas

July 14th, 2008 - 2:33 pm ICT by IANS  

Washington, July 14 (IANS) A new, low-cost method has been developed to help accurately map areas where the groundwater has been contaminated by arsenic. Earlier, identifying high-risk areas required costly sampling campaigns, said researchers who developed the new method to trace the toxin that affects the health of millions, especially in the river deltas of South and Southeast Asia.

Worldwide, more than 100 million people are exposed to excessive amounts of arsenic in drinking water. Arsenic is a contaminant - deriving from natural sources - which is dissolved in groundwater.

If ingested over long periods, even low concentrations can cause damage to health, including hyper-pigmentation of the skin, disorders of liver and kidney function, and various types of cancer.

In many areas, the problem is recognised, but because surface waters are polluted new wells are continually dug, often without testing the pumped water for arsenic.

Researchers, led by geologist Lenny Winkel and environmental chemist Michael Berg, have compiled existing geological data from countries including Bangladesh, Myanmar and others to produce a map of arsenic contaminated areas.

The data related to surface sediments and soil properties, which permits sufficiently accurate conclusions about the chemical and physical conditions in groundwater.

The scientists then studied the statistical relations between 30 surface parameters and arsenic concentrations, and incorporated the eight most relevant variables into a logistic regression model.

In particular, young river deposits with organic rich sediments proved to be indicators of groundwater arsenic contamination. This is apparent from the maps in which the probabilities calculated for elevated arsenic concentrations are presented in a graphical form.

The findings of the study have been published in the latest issue of the journal Nature Geoscience.

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