Diffusive gradients in thin films (DGT): A suitable tool for metals/metalloids monitoring in continental waterbodies at the large network scale

Juliette Rougerie; Rachel Martins de Barros; Rémy Buzier; Delphine Devillers; Patrice Fondanèche; Sophie Lissalde; Julie Leblanc; Margaux Saüt; Jean-Pierre Rebillard; Nicolas Mazzella; Gilles Guibaud

doi:10.1016/j.scitotenv.2020.142147

Diffusive gradients in thin films (DGT): A suitable tool for metals/metalloids monitoring in continental waterbodies at the large network scale

Sci Total Environ. 2021 Feb 1:754:142147. doi: 10.1016/j.scitotenv.2020.142147. Epub 2020 Sep 6.

Affiliations

¹ University of Limoges, PEIRENE-Equipe DIQeau - URA IRSTEA, 123 avenue Albert Thomas, 87060 Limoges Cedex, France.
² University of Limoges, PEIRENE-Equipe DIQeau - URA IRSTEA, 123 avenue Albert Thomas, 87060 Limoges Cedex, France. Electronic address: remy.buzier@unilim.fr.
³ Water Agency Adour-Garonne, 90 Rue du Feretra, 31078 Toulouse Cedex 4, France.
⁴ INRAe, Ecosystèmes Aquatiques Et Changements Globaux, Equipe ECOVEA, 50 Avenue de Verdun, 33612 Cestas, France.

PMID: 33254868
DOI: 10.1016/j.scitotenv.2020.142147

Abstract

The contribution of Diffusive Gradients in Thin films (DGT) passive sampling to continental water quality monitoring was assessed in a real measurement network (6 sampling campaigns, 17 stations). Ten metals/metalloids (Al, Zn, Ni, Cd, Cu, Pb, Cr, As, Se and Sb) were studied using the control laboratory's working conditions with grab and DGT passive sampling. The DGT field deployments were robust, with a 3% sampler loss rate and a <65% average relative deviation between duplicates. Compared to grab sampling, DGT showed a similar quantification frequency for half of the targeted elements but showed a higher frequency for the other half (e.g., Cd quantification at 20% with grab sampling vs. 97% with DGT). Similar concentration trends were established using DGT and grab sampling at most sites throughout the year. Notably, for some elements, trends were only provided by DGT sampling. A study of several DGT blanks showed that the device contamination was occasional and originated primarily from cross-contamination during the disassembly step. Considering this contamination, the operational sensitivity by DGT was at least between 1 and 5 times greater in comparison to that by grab sampling. Estimations of the economic cost revealed that measurement networks cost 2 to 3 times more when monitored by DGT compared to standard grab monitoring. However, the information obtained based on each type of sampling method is different. Grab sampling is easy to implement and can highlight high contamination peaks. The DGT concentrations are averaged over time and are relevant to chronic exposure evaluations. Considering the good performance of the DGT sampling highlighted in this study and its complementarity with grab sampling in terms of water quality assessments, a combination of these two types of sampling, which can be affordable, should improve the water quality evaluation within monitoring networks.

Keywords: Field sampling; Metalloids; Metals; Passive sampling; Water quality network.