Heavy metal removal efficiencies in a river-marsh system estimated from patterns of metal accumulation in sediments

Estuaries have long been thought to be effective traps for river-borne cont aminants; however, accurately predicting removal efficiencies remains probl ematic. In the Quinnipiac River, CT, marsh system, patterns of metal accumu lation (Ag, Cd, Cu, Pb) in sediments were used to estimate heavy metal remo val efficiencies. Linear and multivariate regression models were fit to sed iment metal concentrations to estimate removal curves and surfaces, which a voided the large temporal variability commonly encountered when using direc t water column measurements. Second order regressions normalized to the sho rtest distance to the river channel were found to have the best fit (r > 0. 67) with the lowest standard error (< 32%). The heavy metal removal efficie ncies estimated by comparing total metal accumulation in marsh sediments wi th riverine flux were Ag = 21%, Cd = 6%, Cu = 14%, and Pb = 17%, which are comparable to the maximum removal efficiency of riverine suspended particul ate matter (similar to 28%). (C) 1999 Published by Elsevier Science Ltd. Al l rights reserved.