Tellurium behaviour in a major European fluvial–estuarine system (Gironde, France): fluxes, solid/liquid partitioning and bioaccumulation in wild oysters
|Author(s)||Gil-Díaz Teba1, Schäfer Jörg1, Dutruch Lionel1, Bossy Cécile1, Pougnet Frédérique1, Abdou Melina1, Lerat-Hardy Antoine1, Pereto Clément1, Derriennic Hervé1, Briant Nicolas2, Sireau Teddy2, Knoery Joel2, Blanc Gerard1|
|Affiliation(s)||1 : Université de Bordeaux, UMR CNRS 5805 EPOC, Allée Geoffroy Saint-Hilaire, 33615 Pessac, France
2 : IFREMER – RBE/BE/Laboratoire de Biogéochimie des Contaminants Métalliques, BP 21105, Nantes F-44311, France
|Source||Environmental Chemistry (1448-2517) (CSIRO Publishing), 2019-07 , Vol. 16 , N. 4 , P. 229-242|
|WOS© Times Cited||11|
|Keyword(s)||Garonne River, Gironde Estuary, Lot River, RNO, ROCCH, technology critical element|
Tellurium (Te) is a technology critical element (TCE) with largely unknown environmental behaviour, especially in continent-ocean interface systems. The unknown behaviour results from the lack of studies in aquatic environments and from analytical challenges limiting the determination of its naturally low (ultra-trace) environmental levels. We performed a comprehensive study of Te in the Lot–Garonne–Gironde fluvial–estuarine system to better understand seasonal variations, solid/liquid partitioning (Kd), gross fluxes, estuarine dynamics, and transfer to wild oysters at the estuary mouth. A temporal record (2014–2017) of dissolved (Ted) and particulate (Tep) Te concentrations at five sites in the Lot–Garonne River system shows little differences between sites, with average ~0.9 ng L−1 and ~50 µg kg−1 respective concentrations. Watershed Ted and Tep follow parallel seasonal patterns, which result in constant partitioning (log10 Kd ~4.75 L kg−1), with constant annual gross dissolved fluxes (~15.0 kg y−1) and variable gross particulate fluxes (from 6.50 to 140 kg y−1) entering the Gironde Estuary. Estuarine reactivity in contrasting hydrological conditions (from flood to drought) suggest that grain-size effects and/or estuarine hydrological residence times strongly affect Tep behaviour. Historical records (1984–2017) of Te in wild oysters at the estuary mouth vary from 1.33 to 2.89 µg kg−1 dry weight (d.w.), without any clear long-term trend. This study provides rare knowledge on Te environmental dynamics in aquatic systems, and suggests that, although no current anthropogenic sources were identified in the economically developed Lot-Garonne-Gironde fluvial-estuarine system, there is a non-negligible bioaccumulation in wild oysters at the estuary mouth.