WATER RESOURCES RESEARCH GRANT PROPOSAL
Project ID: 2004GA58B
Title: Biogeochemical Cycling of Arsenic at the Sediment-Water Interface of the Chattahoochee River
Project Type: Research
Focus Categories: Sediments, Water Quality
Keywords: Arsenic, Biogeochemistry, Contaminant Transport, Metalloids, River Beds, Water Chemistry, Water Quality Monitoring
Start Date: 03/01/2004
End Date: 02/28/2005
Federal Funds: $16,000
Non-Federal Matching Funds: $32,037
Congressional District: 5
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 ƒÝg/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.