Impacts of hydrologic variations on chemical weathering and solute sources in the Min River basin, Himalayan–Tibetan region

Impacts of hydrologic variations on chemical weathering and solute sources in the Min River... Feedback between hydrologic variations and chemical weathering is thought to play a crucial role in modulating global carbon cycling. The mechanisms associated with the impacts of hydrologic variations on solute sources and chemical weathering were evaluated by examining the relationships between river discharge and hydrochemistry based on high-frequency sampling of the Min River, which originates in the Himalayan–Tibetan region. Fluid transit times and flow pathways vary with changes in discharge, thereby affecting various biogeochemical processes. Although shorter transit times occur during the high-flow season than during the low-flow season, concentrations of chemical weathering products exhibit chemostatic behaviour (less variation than changes in discharge) in response to increasing discharge due to hydrologic flushing of minerals, which increases the amount of reactive mineral surface area. The contributions of various sources to dissolved loads in the Min River were estimated using a forward model. The calculated annual carbonate and silicate weathering fluxes are 24.1 and 9.6 t/km2 year, respectively. Atmospheric contributions increase with increasing discharge, whereas the contributions of silicate weathering decrease with increasing discharge. Both the carbonate weathering flux (FCarb) and silicate weathering flux (FSil) are positively correlated with the discharge, indicating that temporal variations in chemical weathering fluxes in the Min River are highly affected by hydrologic variations. The slope of the relationship between FCarb and discharge is much greater than that between FSil and discharge due to the rapid dissolution of carbonate minerals, suggesting that carbonate weathering is more sensitive than silicate weathering to hydrologic variations. This study demonstrates that high-frequency sampling is necessary when investigating solute sources and chemical weathering processes in river basins influenced by a monsoon climate. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Environmental Science and Pollution Research Springer Journals

Impacts of hydrologic variations on chemical weathering and solute sources in the Min River basin, Himalayan–Tibetan region

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Publisher
Springer Berlin Heidelberg
Copyright
Copyright © 2017 by Springer-Verlag GmbH Germany
Subject
Environment; Environment, general; Environmental Chemistry; Ecotoxicology; Environmental Health; Atmospheric Protection/Air Quality Control/Air Pollution; Waste Water Technology / Water Pollution Control / Water Management / Aquatic Pollution
ISSN
0944-1344
eISSN
1614-7499
D.O.I.
10.1007/s11356-017-9584-2
Publisher site
See Article on Publisher Site

Abstract

Feedback between hydrologic variations and chemical weathering is thought to play a crucial role in modulating global carbon cycling. The mechanisms associated with the impacts of hydrologic variations on solute sources and chemical weathering were evaluated by examining the relationships between river discharge and hydrochemistry based on high-frequency sampling of the Min River, which originates in the Himalayan–Tibetan region. Fluid transit times and flow pathways vary with changes in discharge, thereby affecting various biogeochemical processes. Although shorter transit times occur during the high-flow season than during the low-flow season, concentrations of chemical weathering products exhibit chemostatic behaviour (less variation than changes in discharge) in response to increasing discharge due to hydrologic flushing of minerals, which increases the amount of reactive mineral surface area. The contributions of various sources to dissolved loads in the Min River were estimated using a forward model. The calculated annual carbonate and silicate weathering fluxes are 24.1 and 9.6 t/km2 year, respectively. Atmospheric contributions increase with increasing discharge, whereas the contributions of silicate weathering decrease with increasing discharge. Both the carbonate weathering flux (FCarb) and silicate weathering flux (FSil) are positively correlated with the discharge, indicating that temporal variations in chemical weathering fluxes in the Min River are highly affected by hydrologic variations. The slope of the relationship between FCarb and discharge is much greater than that between FSil and discharge due to the rapid dissolution of carbonate minerals, suggesting that carbonate weathering is more sensitive than silicate weathering to hydrologic variations. This study demonstrates that high-frequency sampling is necessary when investigating solute sources and chemical weathering processes in river basins influenced by a monsoon climate.

Journal

Environmental Science and Pollution ResearchSpringer Journals

Published: Jun 28, 2017

References

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