Validation and in situ application of an automated dissolved nickel monitor for estuarine studies

The validation of a fully automated dissolved Ni monitor for in situ estuar ine studies is presented, based on adsorptive cathodic stripping voltammetr y (AdCSV). Dissolved Ni concentrations were determined following on-line fi ltration and UV digestion, and addition of an AdCSV ligand (dimethyl glyoxi me) and pH buffer (N-2-hydroxyethylpiperazine-N'-2-ethanesulphonic acid). T he technique is capable of up to six fully quantified Ni measurements per h our. The automated in situ methodology was applied successfully during two surveys on the Tamar estuary (south west Britain). The strongly varying sam ple matrix encountered in the estuarine system did not present analytical i nterferences, and each sample was quantified using internal standard additi ons. Up to 37 Ni measurements were performed during each survey, which invo lved 13 h of continuous sampling and analysis. The high resolution data fro m the winter and summer tidal cycle studies allowed a thorough interpretati on of the biogeochemical processes in the studied estuarine system. (C) 199 8 Elsevier Science B.V. All rights reserved.