
%0 Journal Article
%A Hawke, DJ 
%A Hunter, KA 
%T Dissolved trace metal speciation in the Manuherikia River, Central Otago, New Zealand
%J Marine and Freshwater Research
%D 1992/12/01
%V 43
%N 6
%P 1381-1391
%K 
%R https://doi.org/10.1071/MF9921381
%U https://www.publish.csiro.au/paper/MF9921381 
%X The inorganic speciation of the trace metals Cu, Ni, Cd, Zn and Pb has been calculated for the pristine, subalpine Manuherikia River. Temperature, pH, ionic strength and major-ion composition were found to be important controls on the free-ion activity of trace metals. Metal -CO3-2 species were the most important complexes for Pb, Cu and Ni. The metal-HCO3- species was most important for Cd, and Zn was intermediate. Ni, Zn and Cd were present mainly as the free divalent ion, whereas Pb (up to 81% complexed) and Cu (up to 70% complexed) were strongly affected by ionic interactions. Free-ion activities of Cu2+ and Pb2+ were essentially constant along the length of the river despite significant increases in total dissolved-metal concentrations. Thus, for these metal ions, total dissolved concentrations are a poor indicator of biological availability. 
