The Role of Transported Sediment in the Cycling of Phosphate in Georgia Piedmont Impoundments

Abstract

The high iron content in the soils and resident parent material of the Georgia Piedmont results in significant transport of iron in runoff to receiving waterbodies. Phosphorus cycling in lakes can be significantly affected by the iron cycle. The work presented here describes experiments to test sorption and desorption of phosphate from Bt horizon soil to help illuminate the role of transported sediment in the cycling of phosphorus in Georgia Piedmont impoundments. We conducted sorption capacity experiments on Bt horizon soil, Lake Lanier sediments, and catalyst grade FeOOH. We also describe experiments to test release of phosphate from Bt horizon soil under elevated pH conditions. Sorption capacity of Bt soil and Lake Lanier sediments is greater than that of FeOOH. Phosphate desorption from Bt horizon soil at pH values of 8-10 fits a linear model with greater desorption at higher pH values. The results presented here further support the alternative phosphorus cycling pathway proposed in Parker and Rasmussen (2001).