Comparison of the metal contamination in water measured by diffusive gradient in thin film (DGT), biomonitoring and total metal dissolved concentration at a national scale

Abstract

In this study, we propose to compare the metal contamination in water assessed by three monitoring tools: diffusive gradient in thin film (DGT), caged gammarids and grab samples of the dissolved phase. The study was conducted at a national scale on 101 sites throughout France and involved the deployment of DGT and gammarids at the same time. Cd, Cr, Co, Cu, Mn, Ni, Pb and Zn were measured in DGT, dissolved phase and gammarids. The data set was analyzed with an exploratory data analysis method: multiple factor analysis (MFA), which aims at comparing data sets structured in groups of variables in order to compare the groups and the conclusions to be drawn from the analysis of the data set by each group. No differences were observed for Co and Ni for the three methods. The gammarid group gave the richest information on the contamination of the sites because it discriminated the sites contaminated by Pb and Cd. Depending on the metals, DGT provided more information than grab samples, but less than gammarids. We conclude that the three monitoring tools gave complementary information on metal contamination, and their effectiveness in assessing metal contamination in water depends on the metal and the fraction studied.