SEGH Articles

Trace Metal inputs in French Pyrenees: a spatial and temporal case study in the Upper valley of the Vicdessos

02 May 2013
A human-environment observatory aims to monitor the evolution of human-environment interactions within the Upper Vicdessos valley. The aim is to collect data and integrate them to conduct a transdisciplinary research in a changing environment.

 

The following article comes from the Ecolab – members of the organising team for this year’s International SEGH meeting in Europe. The venue in Toulouse, Southern France promises and exciting and informative series of oral and poster presentations in stunning surroundings in the centre of the city.”

Trace Metals (e.g. Pb, Hg, Cu) are metallic chemical elements in small amounts in natural rocks and soils. However human activities have impacted their biogeochemical cycles through local and global dispersions throughout the world since the beginning of the metallurgy more than 5000 years ago. As some of these trace metals are known to be harmful and can be accumulated in natural environments, it is important to understand the present trace metal inventories in soil.

Our study takes place in the upper valley of Vicdessos (Ariège). This is a mountain catchment situated in the French Pyrenees up to 2600 m above see level. As several places in the whole Pyrenees range, human pressure, variable in time and space, have impacted on the surrounding environment. To be more precise mining and smelting activities (Iron, Ag-Pb Galena), intensive agro-pastoral activities, deforestation are documented for this area at least since the early Middle Ages. These activities have been dispersed metals and contributed to the current contamination of soil, leaving here a chemical legacy. We focus our study on Bassiès valley (photo 1) which is a sub-catchment of the upper-Vicdessos Valley (Cf. map 1). The geomorphological shape of the valley results of glacial erosion of the Bassiès monzogranite basement during the last glacial era. Several lakes and mires are formed in this succession of glacial basins and tills. Since 2009, a human-environment observatory (http://w3.ohmpyr.univ-tlse2.fr/) aims to monitor the evolution of human - environment interactions within this geographic zone. Different projects, from botanical research to economic studies through biogeochemistry, are carried out in this context. The aim is to collect data and integrate them to conduct a transdisciplinary research in changing environment.

This PhD project is involved in such context. The idea is to decipher the different natural and anthropogenic factors influencing trace metals flows and accumulation in the catchment, main objectives are to:

  • Understand when and how trace metals inputs occurred in the past, and the relationship with contemporaneous environment (e.g. land use, mining, smelting, etc.)
  • Highlight temporal variability and origin of present atmospheric trace metals inputs
  • Estimate present inventories and the possible release in the case of environmental changes.

 

To answer these questions, we aim to set up a spatio-temporal approach using environmental archives and atmospheric deposition monitoring. Several cores of environmental archives (Peat, Lakes...) will be analysed to reconstruct past deposition of trace metals on Bassiès catchment (Photo 3). These results should be compared with other studies (palynology, charcoal) and historical data to discuss their possible relationships and influence of changes in environmental pressure on trace metals inputs. Multi-coring will be applied on the Bassiès site to see intra-variability and a Pyrenean coring transect to discuss spatial variability in the last 200 years. Temporal dynamic of actual trace metal deposition is assessed by means of atmospheric deposition clean collectors (Photo 4) along altitudinal transects and soil solution collectors. We will install passive fog collectors designed to ultra-trace metal occult deposition. Special insight will be the study of lead isotopic composition in deposition, cores and surface mosses transects for better understanding of lead sources.

This PhD project is led by Adrien CLAUSTRES in the EcoLab, a laboratory of functional ecology and environment at the University of Toulouse, France. This project is directed by Gaël LE ROUX and Anne PROBST, CNRS researchers also at EcoLab. (http://www.ecolab.omp.eu/).

Adrien Claustres, EcoLab, University of Toulouse, France

adrien.claustres@free.fr

Keep up to date

Submit Content

Members can keep in touch with their colleagues through short news and events articles of interest to the SEGH community.

Science in the News

Latest on-line papers from the SEGH journal: Environmental Geochemistry and Health

  • Date palm waste biochars alter a soil respiration, microbial biomass carbon, and heavy metal mobility in contaminated mined soil 2017-04-19

    Abstract

    A 30-day incubation experiment was conducted using a heavy metal-contaminated mined soil amended with date palm feedstock (FS) and its derivative biochars (BCs) at three pyrolysis temperatures of 300 (BC-300), 500 (BC-500), and 700 °C (BC-700) with different application rates (0.0, 5, 15, and 30 g kg−1) to investigate their short-term effects on soil respiration (CO2–C efflux), microbial biomass carbon (MBC), soil organic carbon (SOC), mobile fraction of heavy metals (Cd, Cu, Pb, Zn, Mn, and Fe), pH, and electrical conductivity (EC). The results showed that FS and BC-300 with increasing addition rate significantly reduced soil pH, whereas SOC, CO2–C efflux, and soil MBC were increased compared to the control. On the contrary, BC-500 and BC-700 increased soil pH at early stage of incubation and have small or no effects on SOC, CO2–C efflux, and MBC. Based on the results, the date palm biochars exhibited much lower cumulative CO2–C efflux than feedstock, even with low-temperature biochar, indicating that BCs have C sequestration potential. Applying BC-700 at 15 and 30 g kg−1 significantly reduced cumulative CO2–C efflux by 21.8 and 45.4% compared to the control, respectively. The incorporation of FS into contaminated soil significantly increased the mobile content of Cd and Mn, but decreased the mobile content of Cu. However, BC-300 significantly reduced the mobile content of Cd, Cu, Pb, and Zn. It could be concluded that low-temperature biochar could be used as a soil amendment for reducing heavy metal mobility in mining contaminated soil in addition to minimize soil CO2–C efflux.

  • Historical record of anthropogenic polycyclic aromatic hydrocarbons in a lake sediment from the southern Tibetan Plateau 2017-04-17

    Abstract

    High-altitude lake sediments can be used as natural archives to reconstruct the history of pollutants. In this work, the temporal distribution of polycyclic aromatic hydrocarbons (PAHs) was determined in a sediment core collected from the southern Tibetan Plateau (TP), which was dated by using the 210Pb dating method and validated with the 137Cs fallout peak. The concentrations of the anthropogenic PAHs (Σ8PAH) in the sediment core ranged from 0.83 to 12 ng/g dw, and the fluxes of the Σ8PAH were in the range of 2.1–27 g/cm2/year. The temporal variations in the concentration and input flux of anthropogenic PAHs were low with little variability before the 1950s, and then gradually increased from the 1950s to the 1980s, and an accelerated increase was observed after the early 1980s. The content of total organic carbon played an insignificant role in affecting the time trends of PAHs in the sediment core. Diagnostic concentration fractions of PAH components indicate PAHs in the lake sediment of the southern TP which are mainly from biomass burning and/or from long-range atmospheric transport.

  • Determination of the potential implementation impact of 2016 ministry of environmental protection generic assessment criteria for potentially contaminated sites in China 2017-04-12

    Abstract

    The Ministry of Environmental Protection of China issued a 3rd draft edition of risk-based Generic Assessment Criteria (the MEP-GAC) in March 2016. Since these will be the first authoritative GAC in China, their implementation is likely to have a significant impact on China’s growing contaminated land management sector. This study aims to determine the potential implementation impact of the MEP-GAC through an in-depth analysis of the management context, land use scenarios, health criteria values adopted and exposure pathways considered. The MEP-GAC have been proposed for two broad categories of land use scenarios for contaminated land risk assessment, and these two categories of land use scenarios need to be further delved, and a MEP-GAC for Chinese cultivated land scenario ought to be developed, to ensure human health protection of Chinese farmers. The MEP-GAC have adopted 10−6 as the acceptable lifetime cancer risk, given the widespread extent and severe level of land contamination in China, consideration should be given to the decision on excess lifetime cancer risk of 10−5. During risk assessment process in practice, it is better to review the 20% TDI against local circumstances to determine their suitability before adopting it. The MEP-GAC are based on a SOM value of 1%, for regions with particularly high SOM, it might be necessary to develop regional GAC, due to SOM’s significant impact on the GAC developed. An authoritative risk assessment model developed based on HJ25.3-2014 would help facilitate the DQRA process in practice. The MEP-GAC could better reflect the likely exposures of China’s citizens due to vapour inhalation by using characteristics of Chinese exposure scenarios, including China-generic building stock, as inputs into the Johnson and Ettinger model as opposed to adoption of the US EPA parameters. The MEP-GAC once implemented will set the trajectory for the development of the investigation, assessment and remediation of land contamination for years.