THE BINDING OF Pb, Zn, AND OTHER METAL IONS IN SUSPENDED RIVERINE PARTICULATE MATTER
PHILIP G. MANNING and XIAOWA WANG
Lakes Research Branch, National Water Research Institute, 867 Lakeshore Road, Burlington, Ontario L7R 4A6
Abstract
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 with those of ferric iron by the relationship [M]/[Fe2+CL] = k1-[Fe3+T]/[Fe2+CL] - nCL-k1 + k2, where k1 and k2 are constants, nCL is the ratio of ferric iron to ferrous iron within the clay structure, M is one of Pb2+, Zn2+, Mn, Cu2+, or Cr, and Fe3+T and Fe2+CL are total ferric iron and clay-bound ferrous iron, respectively. The linear relationship is predicated on the distribution of ferric iron between active hydrated oxides and relatively inactive clay minerals. Lead, zinc, manganese, copper, and chromium ions are bonded to hydrated ferric oxides via a bridging anion, possibly fulvate or humate ion. Coefficients of binding (k1) are, as weight percent of ferric 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, namely a ferric oxide - organic matter assemblage. The metals are relatively unavailable while in suspension in the river.
Keywords: lead, zinc, metals, ferric oxide, binding, particulate matter, availability, river, Trent - Severn Waterway, Ontario.