HEAVY-METAL CONTENT OF SEDIMENTS IN THE CALCASIEU RIVER LAKE COMPLEX, LOUISIANA

The heavy metals Cd, Cr, Cu, Pb, Hg, Ag, and Zn, and the metalloid As were measured in surface sediments at permanent stations located in the Calcasieu River/Lake Complex. The relationships among metal concentrations in different areas of the system were investigated to determine sources, source strength, and transport. The point-source inputs of heavy metals were assumed to be industrial outfalls (Bayou d'Inde) and sewage outfalls (Bayou d'Inde and Contraband Bayou). Although these inputs have not seriously affected the entire river/lake system, stressed regions exist within each bayou. The background levels of arsenic and heavy metals were: 0.60 (As), 0.3 to 1.4 (Cd), 25 (Cr), 10 (Cu), 15 (Pb), < 0.05 (Hg), 0.07 (Ag), and 40 mg kg-1 (Zn). Stations near sewage outfalls and industrial outfalls had increased metal concentrations above these background levels, but the increases were restricted to the regions near the outfalls. The metals discharged into the bayous were not being transported to the remainder of the river/lake complex. © 1990 Kluwer Academic Publishers.