Effects of sample collection device and filter pore size on concentrations of metals in groundwater samples

摘要

The Savannah River Site has conducted a study to statistically quantify differences in metals concentrations as a function of sampling device and filter treatment. Twelve wells screened in unconsolidated coastal plain sediments were sampled for the study. All wells had histories of detectable toxic metals concentrations. Unfiltered and filtered (using 10 and 0.45 micron filters) samples were collected from all wells to evaluate the effects of filtering. To compare the effects of sampling device, the wells were sampled twice, once with a bladder pump and once with a centrifugal pump. An analysis of covariance (ANCOVA) method was used to assess the effects of sampling device and filtration on metals concentrations considering the variation in pH, conductivity, and turbidity among samples. This study demonstrates that when controlled sampling techniques are employed, differences in toxic metals concentrations between filtered and unfiltered samples are not statistically significant. However, variations in sampling devices yield samples with statistically different metals concentrations. The centrifugal pumps, which cause more agitation of the sample and the screened zone than bladder pumps, yield samples with statistically higher metals concentrations.