In situ intercomparison exercise on “home-made” DGT for the monitoring of trace metals, mercury and arsenic in surface freshwaters - INRAE - Institut national de recherche pour l’agriculture, l’alimentation et l’environnement Accéder directement au contenu
Poster De Conférence Année : 2015

In situ intercomparison exercise on “home-made” DGT for the monitoring of trace metals, mercury and arsenic in surface freshwaters

Exercice in situ d'intercomparaison de DGT "home-made" pour la surveillance des métaux, du mercure et de l'arsenic dans les eaux de surface

Résumé

Most monitoring programs for surface waters within a legislative framework such as the Water Framework Directive (WFD) rely on conventional techniques such as spot or automated sampling to determine total dissolved concentration of a target substance. These sampling methods are generally time-consuming, do not take into account temporal variability and could induce samples contamination, loss of analyte or speciation modifications. The Diffusive Gradient in Thin films (DGT) technique is an alternative sampling method to assess a time-weighted average (TWA) metal concentration in surface waters, as it takes into account metal variations during the period of exposure. This passive sampler based on a polyacrylamide diffusive gel and a Chelex resin has been widely used to measure TWA concentration for cationic metals such as cadmium (Cd), nickel (Ni), lead (Pb), zinc (Zn) and copper (Cu). Recently, the gel and/or the resin were modified to propose a similar tool allowing trapping mercury (Hg) species and arsenic (As). These different tools are commercially available but several laboratories are now developing their home-made DGTs. As each laboratory prepares its home-made gel or resin in different working conditions by using different reagents (i.e. purity and/or supplier) and by using different methods to determine diffusive coefficient the comparison of results obtained with these tools could be not relevant. To answer this question, the objective of our study was to compare commercial and “home-made” DGT performances for cationic metals (Cd, Pb, Ni, Cu, Zn, Co) and total mercury during an in situ intercomparison exercise. The in situ intercomparison exercise was carried out in July 2014 in the Deûle River (northern France) for 2 weeks. Results were addressed in terms of (i) blank values, (ii) accumulated metal mass and (ii) TWA concentration by overcoming the analytical bias. First results highlighted the effect of different working conditions on blank values and their impact for the determination of TWA concentrations. Additionally, data showed the importance of characterizing diffusion coefficients for each type of home-made DGT in order to compare them.
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Dates et versions

hal-02601999 , version 1 (16-05-2020)

Identifiants

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A. Magnier, L. Lesven, Y. Gao, A. Dabrin, Marina Coquery. In situ intercomparison exercise on “home-made” DGT for the monitoring of trace metals, mercury and arsenic in surface freshwaters. DGT Conférence, Sep 2015, San Sebastian, Spain. pp.1, 2015. ⟨hal-02601999⟩
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