Seasonal controls on stream metal(loid) signatures in mountainous discontinuous permafrost.

Autor: Skierszkan EK; Department of Geological Sciences, University of Saskatchewan, 114 Geological Sciences Place, Saskatoon S7N 5E2, Canada. Electronic address: elliott.skiers@usask.ca., Carey SK; School of Earth, Environment & Society, McMaster University, 1280 Main Street West, Hamilton L8S 4K1, Canada., Jackson SI; Lorax Environmental Services Ltd., 2289 Burrard Street, Vancouver V6J 3H9, Canada., Fellwock M; Department of Geological Sciences, University of Saskatchewan, 114 Geological Sciences Place, Saskatoon S7N 5E2, Canada., Fraser C; Lorax Environmental Services Ltd., 2289 Burrard Street, Vancouver V6J 3H9, Canada., Lindsay MBJ; Department of Geological Sciences, University of Saskatchewan, 114 Geological Sciences Place, Saskatoon S7N 5E2, Canada.
Jazyk: angličtina
Zdroj: The Science of the total environment [Sci Total Environ] 2024 Jan 15; Vol. 908, pp. 167999. Date of Electronic Publication: 2023 Oct 31.
DOI: 10.1016/j.scitotenv.2023.167999
Abstrakt: We assess physical and chemical processes driving seasonal fluctuations in dissolved (<0.45 μm) trace metal(loid) concentrations in subarctic streams in discontinuous permafrost. Our analysis integrates multiple years of stream hydrometric and geochemical data with geochemical analyses of bedrock, permafrost, and active-layer samples. Three principal flow regimes govern stream hydrology: winter baseflow, spring freshet, and summer high flows. Metal(oid) concentrations in streams respond seasonally to these flow regimes. Baseflows are dominated by discharge of circumneutral-pH groundwater draining fractured bedrock. This discharge acts as a source of metals found as oxyanions or neutrally charged complexes, such as uranium and molybdenum. High stream flows are associated with peak concentrations of aluminium, cobalt, copper, iron, nickel, titanium, and vanadium. Concentrations of the metal cations aluminium, cobalt, copper, nickel, and titanium peak during freshet, when infiltration of snowmelt through organic-rich and moderately acidic soils favors their complexation with dissolved organic carbon. Concentrations of vanadium peak during summer high flows, likely reflecting flow through mineral soils in the active layer and involving reductive dissolution of iron(III)-(oxyhydr)oxides. The seasonal variation of arsenic concentrations is complex; at the majority of catchments it is sourced from shallow flowpaths in the active layer, but it can also be locally associated with discharge of deeper bedrock groundwater, which is spatially constrained by the presence of permafrost. Based on our analysis, we present a conceptual model that describes the flowpaths and processes governing metal(loid) release to streams in discontinuous permafrost. This model provides a framework upon which we consider changes in metal(loid) export into water resources in the context of thawing permafrost.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2023 Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
Externí odkaz: