The Influence of Glacial Cover on Riverine Silicon and Iron Exports in Chilean Patagonia.

Autor: Pryer HV; Bristol Glaciology Centre, Department of Geographical Sciences University of Bristol Bristol UK.; School of Earth Sciences University of Bristol Bristol UK., Hawkings JR; Department of Earth, Ocean and Atmospheric Sciences Florida State University Tallahassee FL USA.; German Research Centre for Geosciences GFZ Potsdam Germany., Wadham JL; Bristol Glaciology Centre, Department of Geographical Sciences University of Bristol Bristol UK., Robinson LF; School of Earth Sciences University of Bristol Bristol UK., Hendry KR; School of Earth Sciences University of Bristol Bristol UK., Hatton JE; School of Earth Sciences University of Bristol Bristol UK., Kellerman AM; Department of Earth, Ocean and Atmospheric Sciences Florida State University Tallahassee FL USA., Bertrand S; Renard Centre of Marine Geology Ghent University Ghent Belgium., Gill-Olivas B; Bristol Glaciology Centre, Department of Geographical Sciences University of Bristol Bristol UK., Marshall MG; Bristol Glaciology Centre, Department of Geographical Sciences University of Bristol Bristol UK., Brooker RA; School of Earth Sciences University of Bristol Bristol UK., Daneri G; Centro de Investigación en Ecosistemas de la Patagonia Coyhaique Chile.; COPAS Sur-Austral Universidad de Concepción Concepción Chile., Häussermann V; Huinay Scientific Field Station Pontificia Universidad Católica de Valparaíso Valparaíso Chile.
Jazyk: angličtina
Zdroj: Global biogeochemical cycles [Global Biogeochem Cycles] 2020 Dec; Vol. 34 (12), pp. e2020GB006611. Date of Electronic Publication: 2020 Dec 17.
DOI: 10.1029/2020GB006611
Abstrakt: Glaciated environments have been highlighted as important sources of bioavailable nutrients, with inputs of glacial meltwater potentially influencing productivity in downstream ecosystems. However, it is currently unclear how riverine nutrient concentrations vary across a spectrum of glacial cover, making it challenging to accurately predict how terrestrial fluxes will change with continued glacial retreat. Using 40 rivers in Chilean Patagonia as a unique natural laboratory, we investigate how glacial cover affects riverine Si and Fe concentrations, and infer how exports of these bioessential nutrients may change in the future. Dissolved Si (as silicic acid) and soluble Fe (<0.02 μm) concentrations were relatively low in glacier-fed rivers, whereas concentrations of colloidal-nanoparticulate (0.02-0.45 μm) Si and Fe increased significantly as a function of glacial cover. These colloidal-nanoparticulate phases were predominately composed of aluminosilicates and Fe-oxyhydroxides, highlighting the need for size-fractionated analyses and further research to quantify the lability of colloidal-nanoparticulate species. We also demonstrate the importance of reactive particulate (>0.45 μm) phases of both Si and Fe, which are not typically accounted for in terrestrial nutrient budgets but can dominate riverine exports. Dissolved Si and soluble Fe yield estimates showed no trend with glacial cover, suggesting no significant change in total exports with continued glacial retreat. However, yields of colloidal-nanoparticulate and reactive sediment-bound Si and Fe were an order of magnitude greater in highly glaciated catchments and showed significant positive correlations with glacial cover. As such, regional-scale exports of these phases are likely to decrease as glacial cover disappears across Chilean Patagonia, with potential implications for downstream ecosystems.
Competing Interests: The authors declare no conflicts of interest.
(©2020. The Authors.)
Databáze: MEDLINE
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