The Diffusive Gradients in Thin Films Technique (DGT) for Trace Metals versus Active Sampling

Abstract

The diffusive gradient in thin films (DGT) technique is an in situ passive sampling method that is designed to accumulate labile metal species in environmental systems. DGTs were applied for the determination of time integrated concentrations of low level dissolved metals in waters in areas of ecological concern. The data revealed heavy metal contamination of waters and tracked the contamination to the source. A comparison of DGT-derived water concentrations with water concentrations measured from grab samples highlighted the effectiveness of passive water samplers for detecting ultra-trace levels of met-als. Comparing active and passive sampling techniques showed that both methods produce similar results when used simultaneously at the same sites. The use of DGT technique along with traditional methods offers an extra cost effective method of independent evaluation of environmental sites as well as more sensi-tive and inexpensive way of obtaining additional information about sites which would be very hard to obtain using active sampling techniques.