THE POTENTIAL POOL OF CO, NI, CU, PB AND CD ORGANIC COMPLEXING LIGANDS IN COASTAL AND URBAN RAIN WATERS

The detection of dissolved ACSV (adsorptive cathodic stripping voltamm etry) Co, Ni, Cu, Cd and Pb in rain waters collected from an urban and a coastal site in the northwest of England is described. The presence of metal complexing organic ligands in rain waters is indicated with an overall percentage of ACSV(non-labile) dissolved metal of the total dissolved metal fraction (=%ACSV(n1/t)) being 33 (33); 28 (35); 26 (3 2); 33 (25); 27 (34): for Co, Ni, Cu, Cd and Pb, respectively, for the urban site (and coastal site). ACSV metal lability is theoretically d efined and is depende nt upon the alpha-coefficient (beta'(MAL) [AL]) of the added ACSV ligand (AL). No major differences were observed betw een %ACSV(n1/t) metal fractions in rain waters collected at the two co ntrasting sites for all the metals considered. As Cu, Pb, Cd and Ni ha d values greater than 10 for their EF(crust) (crustal enrichment facto r), rain water collected from both sites had predominantly anthropic c hemical characteristics. The commonality of the aerosol chemical chara cteristics at the two sites may account for the observed similar (rela tive to total metal concentrations) proportions of metal organic compl exation at the two different sites. The general order of increasing or ganic associations was Cu=Pb=Ni<Co<Cd, although the analytical log alp ha-coefficients (beta'(MAL) [AL]) for each metal were different (9.62- Ni; 9.27-Cu; 5.29-Co; 2.15-Pb; 1.13-Cd). Significant correlations were encountered between ACSV(non-labile) and total dissolved trace metal concentrations of the pooled data from both sites, again an indication of the similarity of the chemical characteristics of the scavenged so luble organic ligands associated with background aerosol material. Cop yright (C) 1996 Elsevier Science Ltd.