Prediction of Heavy Metal Uptake by Marsh Plants Based on Chemical Extraction of Heavy Metals from Dredged Material.

摘要

A field and laboratory study was conducted to establish the extent of heavy metal absorption and uptake by marsh plant species from dredged material and to develop a technique using chemical extraction of heavy metals from dredged material to predict the concentration of heavy metals in marsh plants subsequently grown on the dredged material. Extensive field sampling of marsh plants and dredged material from U.S. Army Corps of Engineers (CE) disposal sites was conducted along the East and Gulf Coasts of the United States. Marsh plant species studied included Spartina alterniflora, Spartina patens, and Distichlis spicata. Four procedures for the extraction of heavy metals from soil were evaluated including water soluble, ammonium acetate exchangeable, dilute acid extractable, and DTPA extractable. Results indicated that most marsh plants colonizing dredged material disposal sites sampled in this study contained relatively low concentrations of Zn, Cu, Cd, Pb, Cr, Ni, and Hg. These concentrations were very similar to those reported for natural coastal marshes. There were a few location, however, in which the concentrations of Zn, Cu, Dc, and Pb in the marsh plants were an order of magnitude greater than the concentrations measured in the majority of marsh plants. The occurrence of these elevated concentrations of heavy metals emphasizes the need for a method to predict heavy metal availability from dredged material to plants. DTPA extraction of heavy metals gave the best correlations with actual heavy metal concentrations in marsh plants.