Issue 9, 2022

Selenium distribution and speciation in waters of pristine alpine lakes from central-western Pyrenees (France–Spain)

Abstract

The speciation of both redox reactive and volatile selenium (Se) compounds, barely reported in pristine aquatic environments, has never been investigated in remote alpine lakes, considered as sensitive ecosystems to detect the effect of global change. This work presents an integrated investigation on Se distribution and speciation conducted in 20 high altitude pristine lakes from the central-western Pyrenees. Five seasonal sampling campaigns were carried out after snowmelt (June/July) and in early fall (October) for the period 2017–2019. Concentrations of total dissolved Se (TDSe) ranged from 7 to 78 ng L−1, with selenate being ubiquitously observed in most cases (median of 61% of TDSe). Selenite was only occasionally detected up to 4 ng L−1, therefore a fraction of TDSe was presumably in the forms of elemental Se(0) and/or selenides. Depth profiles obtained in different lakes showed the occurrence of such Se(−II, 0) pools in bottom hypoxic to anoxic waters. The production of volatile Se compounds presented a low median total concentration (TVSe) of 33 pg L−1 (range 3–120 pg L−1), mainly in the form of dimethylselenide in subsurface samples (median of 82% of TVSe). The Se concentration in lake waters was significantly correlated with the sulphate concentration (ρ = 0.93, p < 0.0001), demonstrating that it is influenced by erosion and dissolution of Se and S-enriched parent bedrocks. In addition, for Se depleted alpine lake-bedrock systems, long-range transport and wet atmospheric depositions represent a major source of Se for lake waters.

Graphical abstract: Selenium distribution and speciation in waters of pristine alpine lakes from central-western Pyrenees (France–Spain)

Supplementary files

Article information

Article type
Paper
Submitted
13 oct. 2021
Accepted
05 janv. 2022
First published
06 janv. 2022

Environ. Sci.: Processes Impacts, 2022,24, 1430-1442

Selenium distribution and speciation in waters of pristine alpine lakes from central-western Pyrenees (France–Spain)

M. Bueno, B. Duval, E. Tessier, A. Romero-Rama, L. Kortazar, L. Á. Fernández, A. de Diego and D. Amouroux, Environ. Sci.: Processes Impacts, 2022, 24, 1430 DOI: 10.1039/D1EM00430A

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