Li and δ7Li as proxies for weathering and anthropogenic activities: Application to the Dommel River (meuse basin). (September 2020)

• Record Type: Journal Article
• Authors: Négrel, Philippe; Millot, Romain; Petelet-Giraud, Emmanuelle; Klaver, Gerard
• Is Part Of: Applied geochemistry. Volume 120(2020)
• Publication Date: 2020-09
• Subjects: Environmental geochemistry -- Periodicals; Water chemistry -- Periodicals; Geochemistry -- Social aspects -- Periodicals; Geochemistry -- Periodicals; 551.9
• DOI: 10.1016/j.apgeochem.2020.104674
• Languages: English
• ISSNs: 0883-2927

Abstract

Abstract: Lithium (Li) contents and isotopes were studied in the Dommel catchment, a small riverine system in northern Belgium and the southern part of the Netherlands discharging into the Meuse River. The study covered surface- and groundwaters in and on sand and gravel in the catchment; it aimed at evaluating the potential of Li isotopes as effective tracers of anthropogenic activities in addition to tracing water/substratum interaction processes within a sandy environment. Dissolved lithium concentrations in the Dommel catchment span one order of magnitude, ranging from 1.55 to 39.20 μg/L with a mean concentration of 6.58 μg/L, higher than the worldwide riverine average of 1.9 μg/L. Dissolved δ 7 Li varies from +5.4‰ to +27.8‰. Part of the catchment is impacted by smelter effluents with Li concentrations in the range 91–526 μg/L (mean value 288.36 μg/L) and a δ 7 Li of around +25.6‰ before dilution along the flowpaths of the catchment basin. To interpret the dataset in terms of using Li isotopes as a proxy for anthropogenic activity, we first applied an atmospheric-input correction to waters for both Li concentration and δ 7 Li, as rain contributes an important fraction of the dissolved elements in Dommel waters (8–100% of Li in waters is of atmospheric origin; 100% means no interaction with rocks, no anthropogenic disturbance). Then, we determined and quantified the anthropogenic influence using δ 7 Li and mixing equations for the impacted parts of the catchment. Finally, we added constraints on the water/substratum interaction in this mostly sandy-feldspar soil catchment through the δ 7 Li and Li/Na ratios, highlighting the role of water-residence time in the system on weathering intensity. Highlights: Li and δ7Li as proxies for weathering and anthropogenic activities. The δ7Li of the main river samples is consistent with the influence of smelter effluents. Lithium and its isotopes are effective tracers of industrial discharge into the river. The variation in atmospheric-corrected δ7Li reflects varying influence of weathering.