KINETIC-STUDIES OF ALUMINUM AND ZINC SPECIATION IN RIVER WATER AND SNOW

Kinetic studies of chemical speciation by the Chelex-100 batch technique revealed aluminum is present both as an aquo ion and as simple complexes of inorganic ligands in snow, but probably bound to macromolecule complexants and/or colloidal substances in the Rideau River surface water. Two kinetically distinguishable components of aluminum having dissociation rate constants of 1.1 x 10(-2), less than or equal to 5.4 x 10(-4) s(-1) and three kinetically distinguishable components of aluminum having dissociation rate constants of 5.5 x 10(-3), 8.4 x 10(-4)less than or equal to 6.3 x 10(-5) s(-1) were observed in snow and river surface water, respectively. One kinetically distinguishable component of zinc having a dissociation rate constant of 9.1 x 10(-3) s(-1), and three kinetically distinguishable components of zinc having dissociation rate constants of 8.5 x 10(-3), 2.5 x 10(-3), less than or equal to 6.0 x 10(-5) s(-1), were observed in snow and river surface water, respectively. Use of inductively-coupled plasma mass spectrometry (ICP-MS) with the solution nebulizer to follow the kinetics of the uptake of aluminum and zinc by the Chelex resin in the Chelex batch technique allowed collection of many more data points in the same time range than were obtainable by graphite platform furnace atomic absorption spectrometry (GFAAS) with an automatic sampler, with the result that ICP-MS had a greater ability to resolve labile complexes than GFAAS. ICP-MS is therefore preferable to GFAAS for kinetic studies of metal speciation in aqueous samples.