THE BINDING OF PB, ZN, AND OTHER METAL-IONS IN SUSPENDED RIVERINE PARTICULATE MATTER

The concentrations ([]) of lead, zinc, manganese, copper, and chromium ions in suspended particulate matter collected over a two-year period from the Trent - Severn Waterway, Ontario, are linearly correlated wi th those of ferric iron by the relationship [M]I/[Fe-CL(2+)] = k(l).[F e-T(3+)]/[Fe-CL(2+)] - n(CL).k(1) + k(2), where k(1) and k2 are consta nts, n(CL) is the ratio of ferric iron to ferrous iron within the clay structure, M is one of Pb2+, Zn2+, Mn, Cu2+, or Cr, and Fe-T(3+) and Fe-CL(2+) are total ferric iron and clay-bound ferrous iron, respectiv ely. The linear relationship is predicated on the distribution of ferr ic iron between active hydrated oxides and relatively inactive clay mi nerals. Lead, zinc, manganese, copper, and chromium ions are bonded to hydrated ferric oxides via a bridging anion, possibly fulvate or huma te ion. Coefficients of binding (k(1)) are, as weight percent of ferri c iron in oxide, 0.57 +/- 0.04 for lead, 1.1 +/- 0.1 for zinc, 90 +/- 10 for manganese, 1.0 +/- 0.1 for copper, and 0.5 +/- 0.1 for chromium ions. These metal ions share a common carrier with phosphate ion, nam ely a ferric oxide - organic matter assemblage. The metals are relativ ely unavailable while in suspension in the river.