DS0101 - Comprendre et prévoir les évolutions de notre environnement

TRACE METAL LEGACY on MOUNTAIN AQUATIC ECOGEOCHEMISTRY – TRAM

TRACE METAL LEGACY on MOUNTAIN AQUATIC ECOGEOCHEMISTRY

Following the onset of the industrial revolution and the use of fossil energy, humans can now indisputably be seen as major geological agents. At present, anthropogenic fluxes of up to 62 chemical elements surpass their corresponding natural fluxes. Due to their geological features mountain environments have been exploited since the beginning of metallurgy.

Metal legacy

As a response to the 2015 ANR panel?s call for a better understanding of the critical zone, ecosystems (both Axe 1), ecotoxicology (Axe 2) , TRAM is in our opinion a promising interdisciplinary and integrative project to face the different following challenges: 1) TRAM will assess changes in the introduction and transfer of PHTE over Millenia using innovative geochemical and isotopic tracers, 2) TRAM will further combine a geochemical approach with ecological analyses to define the impact of PHTE on biodiversity and ecosystem services, 3) TRAM will develop a range of indicators to make the impact of PHTE on the mountain critical zone clearer to decision makers and stakeholders, considering also hydrological, biogeochemical modelling and GIS analyses.

We will focus on two main areas, geologically similar, where peat bogs and lake sediments provide background, ancient and present values of the PHTE contamination: -The heart area of the Parc National des Pyrénées (PNP) and the neighboring natural reserve of Néouvielle, further denominated NEO, -The Haute Ariège where the “Observatoire Hommes et Milieu Pyrénées Haut-Vicdessos” (funded by the LabEx DRIIHM) is located,
Task 1 will focus on present release, transfer and impact of PHTE in the Pyrenees critical zone
Task 2 will focus on the ecological history of PHTE' release in the Pyrenees
Task 3 will use the SWAT model to understand and model the functioning ot the mountain critical zone for past, present and future conditions.

TRAM will draw upon interdisciplinary expertise in soil and catchment modelling, PHTE chemistry, isotope tracing and biotic impacts, to tackle the challenges of understanding and predicting the impacts of PHTEs in mountain critical zones under changing global conditions. As a response to the 2015 ANR panel?s call for a better understanding of the critical zone, ecosystems (both ANR Axe 1), ecotoxicology (ANR Axe 2) , TRAM is in our opinion a promising interdisciplinary and integrative project that will aim at: 1) TRAM will assess changes in the introduction and transfer of PHTE over Millennia using innovative geochemical and isotopic tracers, 2) TRAM will further combine a geochemical approach with ecological analyses to define the impact of PHTE on biodiversity and ecosystem services, 3) TRAM will develop a range of indicators to make the impact of PHTE on the mountain critical zone clearer to decision makers and stakeholders, considering also hydrological, biogeochemical modelling and GIS analyses. We will investigate the intimate relationship between organic matter and PHTE in the mountain critical zone in an area that has been repeatedly subjected to human impacts including mining and in an area which is now protected and with no history of mining. We will investigate PHTE stream transfers to the biota by comparing streams with different trophic webs. By comparing the outputs of hydro-geochemical models with the data obtained from environmental archives, we will improve the robustness of models on longer time scales and pinpoint the technical barriers to understand the future of the mountain critical zone.

Since 2009, EcoLab has hired 3 young CNRS researchers + one young lecturer in the different fields of biogeochemistry. TRAM is a unique opportunity for them to develop an integrative research in common with more experienced geochemists, ecologists and hydrologists at the University of Toulouse. TRAM will bridge the gap between biogeochemists and ecologists in Toulouse using state of the art and innovative tools. The ANR funding is a pertinent investment that will be use locally to further develop researches in the Pyrenees but also assist in bringing to life new concepts on the ecological functioning of the mountain critical zone, that will be used in other mountain ranges and in equivalent boreal, arctic and sub-antarctic zones. TRAM will be an ideal development tool to apply to European (ERC) and International (Belmont, FuturEarth) calls.
TRAM integrates studies of present Pyrenees environment with an additional paleo-perspective to improve understanding of long-term processes and feedbacks in the mountain critical zone. TRAM contributes clearly to demonstrate the utilities (e.g. water, recreational fishing, and tourism) of the mountain critical zone (Axe 5 of the ANR call) through a risk assessment exercise by combining modelling and geographic information system. TRAM members work closely with national parks, water agencies, electricity companies (EDF, GDF-Suez) and fishermen's associations. Results will also be disseminated to ski resorts, large water consumers and major economic players in the Pyrenees. Improving water management to be more sustainable and improving the quality of water is a major priority for the European Union.

All scientific results of TRAM will be presented at International Conferences and published in top-ranked ecological and geochemical journals. The lead PI and co. I (all “young researchers”) have an accumulated >100 rank A publications, which illustrates a high efficiency of scientific publication. All results will be published in the public domain, without particular necessity for data/interest protection. They will be integrated in national and international databases (OHM database, PANGEA database). A major effort will be the education of MSc students (see Table 3: Msc participants). Our work in the Parc National des Pyrénées will be presented to National Park visitors through poster and oral communications. On the entire range of the Pyrenees, our results on water and ecosystem qualities will be disseminated to water and environmental agencies. TRAM participants are and will contribute to scientific outreach activities in their host institutions such as „Fête de la Science?. The PI and the main task leaders are organizing and managing scientific sessions on TRAM topics at the Goldschmidt, INQUA or Réunion des Sciences de la Terre conferences.

Following the onset of the industrial revolution and the use of fossil energy, humans can now indisputably be seen as major geological agents. At present, anthropogenic fluxes of up to 62 chemical elements surpass their corresponding natural fluxes. Due to their geological features mountain environments have been exploited since the beginning of metallurgy. The Pyrenees are no exception as many mining sites in the region have been dated back to the Bronze Age thus allowing a potential human impact on the environment on millennial scales. Furthermore, high altitude soils are often shallow and thus susceptible to erosional processes. The mountain critical zone is therefore sensitive to human-induced environmental changes - e.g. agriculture, mining, clear cutting, as well as to impact of long-term climate change and associated rapid environmental changes. For example, flooding can remobilize trace metals stored in soils and mining heaps and impact downstream natural, agricultural but also coastal ecosystems. Peatlands, a reoccurring ecosystem in mountainous environments, acts as reservoirs of organic matter. Due to peats ability to retain trace metals and radionuclides these natural environments can be considered as a pollutant “sponge” which have accumulated contaminants since the beginning of the metallurgy and have acted as natural filters for toxic elements (e.g. Arsenic, mercury or lead) since the last deglaciation.
Based on previous results on trace metal concentrations in the Central Eastern Pyrenees (Le Roux & Claustres, unpublished), we estimate that more than 600 tons of anthropogenic Pb is stored in peatlands and organic soils but also in lake sediments on the northern slope of the Pyrenees. Similar conclusions can be drawn for other metals. The fate of these potentially harmful trace elements (PHTE; i.e. Pb, Sb or Hg) in relation to long-term climate change or rapid environmental changes is poorly understood. Once these elements are remobilized within the critical zone, the catchment can become highly enriched in the bioavailable fraction of these PHTE (exceeding the recommended guideline values). Several PHTE could also be bio-accumulated in fish and other river biota, modify benthic communities and affect the quality of domestic water.
The legacy of trace metal stocks in the mountain critical zone is poorly understood and the Pyrenees provide a perfect mountain range for detailed scientific investigations of the fate and the impact of those PHTE on the ecological functioning of mountain catchments.
As a response to the 2015 ANR panel’s call for a better understanding of the critical zone, ecosystems (both Axe 1), ecotoxicology (Axe 2) , TRAM is in our opinion a promising interdisciplinary and integrative project to face the different following challenges:
1) TRAM will assess changes in the introduction and transfer of PHTE over Millenia using innovative geochemical and isotopic tracers,
2) TRAM will further combine a geochemical approach with ecological analyses to define the impact of PHTE on biodiversity and ecosystem services,
3) TRAM will develop a range of indicators to make the impact of PHTE on the mountain critical zone clearer to decision makers and stakeholders, considering also hydrological, biogeochemical modelling and GIS analyses.

Project coordinator

Monsieur Gael Le Roux (Centre National de la Recherche Scientifique/Laboratoire d'Ecologie Fonctionnelle et Environnement)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

CNRS/EcoLab Centre National de la Recherche Scientifique/Laboratoire d'Ecologie Fonctionnelle et Environnement

Help of the ANR 272,017 euros
Beginning and duration of the scientific project: September 2015 - 36 Months

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