A PROTOCOL FOR MINIMIZING CONTAMINATION IN THE ANALYSIS OF TRACE-METALS IN GREAT-LAKES WATERS

The precautions and procedures aimed at minimizing contamination artifacts during the collection, filtration, and analysis of trace metals in fresh water are described. The techniques for proper decontamination of sample containers and labware and for field blanks are also presented. Samples are obtained using a portable clean laboratory and analyzed in a Class 100 pressurized room. Preliminary results obtained using the protocols described cast doubt on most of the published data on trace metal concentrations in the Great Lakes. The profiles of dissolved metal concentrations in the water column of Lake Ontario show very distinctive source-dependentfeatures obfuscated in earlier studies by poor data quality.