# Impact of atmospheric pollution inputs and climate change on dissolved inorganic carbon fluxes in karst aquifers: evidences from a 36 years past monitoring of karstic watersheds.

Stephane Binet, Jean-Luc Probst, Christelle Batiot-Guilhe, Jean-Luc Seidel, Christophe Emblanch, Nicolas Peyraube, Michel Bakalowicz, Anne Probst

► To cite this version:

Stephane Binet, Jean-Luc Probst, Christelle Batiot-Guilhe, Jean-Luc Seidel, Christophe Emblanch, et al. Impact of atmospheric pollution inputs and climate change on dissolved inorganic carbon fluxes in karst aquifers: evidences from a 36 years past monitoring of karstic watersheds. 19th EGU General Assembly, 2017, Vienne, Austria. pp.17051. hal-03552731

HAL Id: hal-03552731

https://hal.science/hal-03552731

Submitted on 3 Feb 2022

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>
<figure><img src="image_2.png" /></figure>

# Impact of atmospheric pollution inputs and climate change on dissolved inorganic carbon fluxes in karst aquifers: evidences from a 36 years past monitoring of karstic watersheds.

Stephane Binet (1), Jean-Luc Probst (2), Christelle Batiot-Guilhe (3), Jean-Luc Seidel (3), Christophe Emblanch (4), Nicolas Peyraube (5), Alain Mangin (), Michel Bakalowicz (3), and Anne Probst (2)

(1) CNRS Université d'Orléans, ISTO, Orleans, France (stephane.binet@univ-orleans.fr), (2) ECOLAB Université de Toulouse, CNRS, INPT, OMP, France, (3) HSM, Univ. Montpellier, Montpellier, France, (4) EMMAH, Université d'Avignon et des Pays de Vaucluse, Avignon, France, (5) Université de Bordeaux, Bordeaux, France

Atmospheric pollution is known to modify the soil CO₂ consumption associated with carbonate bedrock weathering. To evidence the long term feedbacks of atmospheric pollution and climate change on this chemical reaction, we investigated the inorganic carbon fluxes monitored weekly from 1979 to 2006 in a small forested karstic watershed in the Pyrénées Mountains, characterized by a large precipitation variability, a 0.025 °C air temperature increase per year and a low agricultural pressure.

The yearly average concentrations of [Ca + Mg] and dissolved inorganic carbon increases of about 0.057 meq.L⁻¹.yr⁻¹ and the 0.1 meq.L⁻¹.yr⁻¹, respectively. The gap relative to the 1:2 relationship between [Ca + Mg] and HCO₃⁻ (in mmole. L⁻¹), noted Delta-HCO₃⁻, was founded to be driven by the atmospheric pollution inputs, producing strong acids that inhibit the consumption of carbon from soil during the carbonate dissolution processes. In addition, atmospheric temperature increase is correlated with the [Ca +Mg] change, whereas the decrease of the atmospheric acid inputs observed since the seventies, is linked with a + 0.0022 meq.L⁻¹.yr⁻¹ increase in Delta-HCO₃⁻.

Similar trends in Delta-HCO₃⁻ change were found over other karstic watersheds monitored more recently in the framework of the SNO KARST, one the observatory networks from the OZCAR Research Infrastructure, highlighting that Delta-HCO₃⁻ changes over time were partially controlled by atmospheric pollution inputs. The re-interpretation of hydrochemical databases using this Delta-HCO₃⁻ indicator enables to evaluate better the impact of atmospheric pollution load and climate change on surface waters. In an indirect way, the dephasing between atmospheric loads recorded in precipitation and Delta-HCO₃⁻ observed in groundwater could be a new tracer method to estimate groundwater residence times.