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A Forty-Year Karstic Critical Zone Survey (Baget Catchment, Pyrenees-France): Lithologic and Hydroclimatic Controls on Seasonal and Inter-Annual Variations of StreamWater Chemical Composition, pCO2, and Carbonate Equilibrium

Ulloa-Cedamanos, Francesco and Probst, Jean-Luc and Binet, Stéphane and Camboulive, Thierry and Payre, Virginie and Pautot, Corinne and Bakalowicz, Michel and Beranger, Sandra and Probst, Anne A Forty-Year Karstic Critical Zone Survey (Baget Catchment, Pyrenees-France): Lithologic and Hydroclimatic Controls on Seasonal and Inter-Annual Variations of StreamWater Chemical Composition, pCO2, and Carbonate Equilibrium. (2020) Water, 12 (5). 1-29. ISSN 2073-4441

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Official URL: https://doi.org/10.3390/w12051227

Abstract

The long-term trends and seasonal patterns of stream water chemical composition in a small remote forested karst catchment, were investigated from 1978 to 2018. Calcium, magnesium, and bicarbonates, the dominant ions, increased over the period together with temperature, while sulfates decreased. Carbonate and sulfate mineral dissolution was the main source of these elements. These trends and the seasonal opposite patterns of discharge vs. temperature, calcite saturation index vs. pCO2 and bicarbonate vs. sulfates, suggested the influence of discharge, of reduced long-range atmospheric pollution, and of increasing air temperature on biological activity and carbonate dissolution. Furthermore, the hydrological regime controlled the seasonal stream water chemical composition and fluxes by: (i) a dilution during the high discharge period, (ii) a change in the contribution rate of the waters draining different lithological areas in the catchment, e.g., the increased sulfates to bicarbonates ratio during summer low flows, with a maximum alkalinity decrease of 24%, and (iii) a “piston” and a “flushing” effects of dissolved elements stored in soils and epikarst with the first autumn heavy rains. Long-term stream water hydrochemical surveys of karst system have proved to be powerful indicators of biogeochemical processes, water sources and pathways under variable natural and anthropogenic environmental pressure conditions.

Item Type:Article
Additional Information:This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY)
HAL Id:hal-02896444
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
French research institutions > Institut de Recherche pour le Développement - IRD (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
Other partners > Université de Montpellier 2 (FRANCE)
French research institutions > Bureau de Recherches Géologiques et Minières - BRGM (FRANCE)
Other partners > Institut national des sciences de l'Univers - INSU (FRANCE)
Laboratory name:
Funders:
CNRS-INEE - SNO KARST - IR OZCAR - IR RZA - Ministère de l'Enseignement Supérieur, de la Recherch et de l'Innovation
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Deposited On:10 Jul 2020 10:03

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