Water Resources Research Act Program

Details for Project ID 2004GA58B

Biogeochemical Cycling of Arsenic at the Sediment-Water Interface of the Chattahoochee River

Institute: Georgia
Year Established: 2004 Start Date: 2004-03-01 End Date: 2005-02-28
Total Federal Funds: $16,000 Total Non-Federal Funds: $32,037

Principal Investigators: Martial Taillefert

Abstract: The adverse human health effects of arsenic have been known for several centuries. The toxicity and biochemical behavior of arsenic depends on its chemical form. In natural environments, arsenite (As(III)) is not only more mobile but can be greater than 60 times more toxic than arsenate (As(V)) salts, or organoarsenic compounds. Recently, it has been shown that elevated concentrations of dissolved arsenic can be found in the Chattahoochee River downstream from two coal- fire power plants but upstream from Westpoint Lake, a freshwater reservoir located an hour southwest of Atlanta (GA) that provides drinking water, flood control, hydroelectric power, navigation, wildlife development, and general recreation for Southwest Georgia. In a preliminary study, we found that dissolved arsenic in the sediment porewaters of the Chattahoochee river can reach concentrations up to the limit of the new Federal Primary Drinking Water Standard (i.e 10 /L) passed by the USEPA in 2001. In addition, we found that 60 to 200 nM cm-2 yr-1 of arsenate fluxes out of the sediment back into the overlying water. These sediments are anoxic, suggesting that arsenate could be reduced to arsenite and diffuse out of the porewaters. Interestingly, very little is known about the dynamics of the chemical and biological transformations of arsenic in natural systems, and it is possible that the exchange of arsenic between the sediment and the water column be episodic and affect the natural ecosystem as well as the drinking water supply.