Lessons from a large scale deployment of DGT in the Seine basin

Emmanuelle Uher (1) , C. Mirande-Bret (2) , Catherine Gourlay-Francé (1)

1 UR HBAN - Hydrosystèmes et Bioprocédés
2 LEESU - Laboratoire Eau, Environnement et Systèmes Urbains

Diffusive Gradient in Thin film (DGT) is a speciation technique now commonly used in the scientific literature to assess metallic contamination in water. However applications usually take place in a same watercourse or in neighbouring sites. We propose here to present the first results of a large scale deployment of DGTs. The main objective of the project, which is supported by the French water agency of the Seine-Normandie basin, is to evaluate the potential of passive samplers as monitoring tools. DGT devices were deployed in 45 sites, on 30 locations in the entire Seine river basin. The sampling area was 500 km long and 200 km wide around Paris. The total sampling period lasted over the whole 2009 year. Restricted gels of 0.78 were used to measure labile Cd, Cr, Co, Cu, Mn, Ni, Pb and Zn. In parallel, raw and filtered water samples were collected to measure total and dissolved metals. General physico-chemical parameters were also measured. The whole set of measurements constitute a rich dataset including large and small rivers, and reference as well as impacted sites. The results first allow us to draw a map of total, dissolved and labile metal concentrations, representing the spatial variability of metal contamination in the Seine basin. Moreover, considering the temporal variability, different behaviours, depending on the metal, can be identified. The large scale deployment of DGT in the Seine river basin was successful: all the samples have been interpreted and are exploitable, whereas the dissolved metal samples are sometimes under the detection limit. We have then built a representative data set on the water contamination in labile metal of an urban impacted basin. The results are also interpreted as labile percentage, showing the operationally possible values of lability in contrasted environmental conditions. A first approach of the factors influencing the lability highlights the significance of the nature of the organic matter to interpret the lability of the metals.

Mots clés: METAUX; SEINE BASSIN; DGT; SPECIATION

Domaines: Sciences de l'environnement

Emmanuelle Uher, C. Mirande-Bret, Catherine Gourlay-Francé. Lessons from a large scale deployment of DGT in the Seine basin. Environmental Chemistry Group Bulletin, 2011, p. 1 - p. 8. ⟨hal-00582436⟩