THE EFFECT OF SALINITY ON BINDING OF CD, CR, CU AND ZN TO DISSOLVED ORGANIC-MATTER

Salinity can affect binding of metals to humic acid and thus affect bi oavailability, however, the effects are poorly understood. The fractio n of Cu, Zn, Cd and Cr (at 100 mu g/L) complexed with Suwannee River H umic Acid (SRHA) was measured at salinities of 0,1, 3, 10, and 15 psu using 1000 Dalton ultrafiltration membranes. In distilled water, 10 mg SRHA/L bound at least 40% of each metal. Except for Cu, metal binding decreased to less than 20% at salinities between 1 and 15 pan. Copper binding decreased ro 27% at 3 psu, but increased to approximately 60% bound at 15 psu. Copper complexation with natural dissolved organics from a local estuary was also measured and ranged from 25 to 100%. Pub lished by Elsevier Science Ltd.