Monday, November 13, 2006

Deciphering Trends in the Spatial Variation of Groundwater Arsenic Concentrations in the Lower Mekong Basin, Cambodia.

Guangchao Li, Matthew Polizzotto, and Scott Fendorf. Stanford Univ, GES, 118 Bruan Hall, Stanford, CA 94305

Arsenic is a contaminant in the groundwater of Holocene aquifers throughout Southeast Asia. Presently, there are many unresolved issues concerning the distribution of arsenic within the aquifers of the region and the processes by which it is liberated from the solid phase.  In particular, there is extensive spatial variation in groundwater arsenic concentrations such that wells within 100 meters of one another can often have vastly differing concentrations.  We have established a field site in the Lower Mekong Delta of Cambodia and have installed a 3-dimensional network of wells to monitor arsenic concentrations and to investigate aqueous and solid-phase properties.  Currently we are evaluating the impacts of physical and chemical factors on the arsenic distribution in order to elucidate trends in the spatial variation.  Such analyses are vital for predicting areas where arsenic concentrations may be high enough to pose a severe risk to human health.