Rates of microbial metabolism in deep coastal plain aquifers

Rates of microbial metabolism in deep anaerobic aquifers of the Atlantic coastal plain of South Carolina were investigated by both microbiological and geochemical techniques. Rates of [2-¹⁴C]acetate and [U-¹⁴C]glucose oxidation as well as geochemical evidence indicated that metabolic rates were faster in the sandy sediments composing the aquifers than in the clayey sediments of the confining layers. In the sandy aquifer sediments, estimates of the rates of CO₂ production (millimoles of CO₂ per liter per year) based on the oxidation of [2-¹⁴C] acetate were 9.4 × 10⁻³ to 2.4 × 10⁻¹ for the Black Creek aquifer, 1.1 × 10⁻² for the Middendorf aquifer, and