Bioaccumulation et bioindication par les lichens de la pollution atmosphérique actuelle et passée en métaux et en azote en France : sources, mécanismes et facteurs d'influence

La contamination atmosphérique par les métaux/métalloïdes (As, Cd, Cu, Pb, Sb, Zn…) et par les composés azotés impacte durablement les écosystèmes. L’évaluation des dépôts atmosphériques responsables de ces effets néfastes reste éparse car complexe, en particulier dans les environnements éloignés des sources de contamination comme les massifs forestiers. La prospection et l’estimation des éléments traces et de l’azote apportés dans ces dépôts ont été réalisées à l’échelle nationale à travers deux approches de biosurveillance par les lichens et les mousses : la bioaccumulation et la bioindication. L’enregistrement des éléments traces par les organismes indique une forte pression lithogénique dans ces milieux éloignés des sources directes, qui s’inclut dans le bruit de fond géochimique (e. g. Al, As, Co, Cr, Fe, Ni et Ti). Des sources additionnelles issues des activités anthropiques plus locales complètent régionalement les cortèges des éléments chimiques enregistrés (Cd, Cu, Sb ou Zn). La comparaison des échantillons de lichens et de mousses avec des spécimens historiques d’herbiers nous permet de retrouver ce contexte régional durant les siècles passés, et notamment de conforter les signatures lithologiques à travers le temps grâce aux terres rares. Ainsi, l’utilisation du charbon fossile apparaît être la source de contamination métallique dominante durant la fin du XIX e siècle et le début du XX e siècle, et plus récemment, une source additionnelle comme le transport routier (cas de Pb) a pu être notée. En parallèle, des facteurs influençant la bioaccumulation des métaux ont été testés : l’espèce considérée joue sur la capture des particules atmosphériques à travers la morphologie du thalle, et l’écorce support ne présente que peu d’influence. En considérant les signatures des dépôts atmosphériques, la végétation au travers des pluviolessivats apparaît influencer davantage les mousses terricoles que les lichens corticoles, ces derniers étant plus représentatifs des dépôts totaux. Des expérimentations de sorption/désorption montrent un processus rapide d’accumulation (une semaine) pour Pb et Cd, mais ne montrent ni compétition entre les métaux bioaccumulés, ni influence du lessivage sur la bioaccumulation. De nouvelles données concernant la sensibilité des espèces lichéniques face aux polluants métalliques ont pu être obtenues à partir de relevés de bioindication couplés à des analyses statistiques multivariées. ABSTRACT : The atmospheric contamination by metals/metalloids (As, Cd, Cu, Pb, Sb, Zn…) and by nitrogen compounds impact the ecosystems. The atmospheric deposition is responsible of these harmful effects and its evaluation is complex and missing, particularly in remote environments like forest areas. The monitoring of trace element and nitrogen deposition at the national scale is carried out through two different approaches of biomonitoring by lichens and mosses: bioaccumulation and bioindication. The metal bioaccumulation points out a strong lithogenic pressure in these remote areas that is included in the geochemical background (e. g. Al, As, Co, Cr, Fe, Ni and Ti). Additional sources from more local anthropogenic activities are responsible for the regional context by the accumulation of other chemical elements (Cd, Cu, Sb or Zn). The comparison of current samples with herbarium specimens allows us getting back to historical regional influence one and half century ago, including consolidating the lithological influence over the time by rare earth elements. The use of fossil coal appears as a dominant source of metallic contamination in the late 19th century and the beginning 20th century. In parallel, the factors influencing the bioaccumulation of metals were evaluated: the entrapment of atmospheric particles is influenced by the morphology of the thallus but not by the bark. Considering the atmospheric deposition signature, vegetation via throughfall was found to be more influent for terricolous mosses than for corticolous lichens. Additional experiments of sorption/desorption showed a quick accumulation process (one week) for Pb and Cd, but neither metal competition, nor leaching influence on bioaccumulation were highlighted. New data on lichen species sensitivity to metal pollutants have been compiled through multivariate statistical analysi

Origin and distribution of rare earth elements in various lichen and moss species over the last century in France

Rare earth elements (REE) are known to be powerful environmental tracers in natural biogeochemical compartments. In this study, the atmospheric deposition of REE was investigated using various lichens and mosses as well as herbarium samples from 1870 to 1998 from six major forested areas in France. The comparison between the REE distribution patterns in organisms and bedrocks showed a regional uniformity influence from dust particles originating from the bedrock and/or soil weathering that were entrapped by lichens and mosses. These lithological signatures were consistent over the last century. The REE patterns of different organism species allowed minor influence of the species to be highlighted compared to the regional lithology. This was even true where the morphological features played a role in the bioaccumulation levels, which were related to the variable efficiency in trapping atmospheric dust particles. A comparison between REE profiles in the organisms and bark indicated a lack of influence of the substrate on lichen REE content. Lichens and mosses appear to be robust passive monitors of REE atmospheric deposition over decades because the mineral data was preserved in herbarium samples despite organic degradation being shown by carbon isotopes and SEM observations. To overcome the bias of REE concentration that resulted from organic degradation, the use of a normalized method is recommended to interpret the historical samples

Comparing early twentieth century and present-day atmospheric pollution in SW France: a story of lichens

Lichens have long been known to be good indicators of air quality and atmospheric deposition. Xanthoria parietina was selected to investigate past (sourced from a herbarium) and present-day trace metal pollution in four sites from South-West France (close to Albi). Enrichment factors, relationships between elements and hierarchical classification indicated that the atmosphere was mainly impacted by coal combustion (as shown by As, Pb or Cd contamination) during the early twentieth century, whereas more recently, another mixture of pollutants (e.g. Sb, Sn, Pb and Cu) from local factories and car traffic has emerged. The Rare Earth Elements (REE) and other lithogenic elements indicated a higher dust content in the atmosphere in the early twentieth century and a specific lithological local signature. In addition to long-range atmospheric transport, local urban emissions had a strong impact on trace element contamination registered in lichens, particularly for contemporary data

Investigation of spatial and temporal metal atmospheric deposition in France through lichen and moss bioaccumulation over one century

Lichens and mosses were used as biomonitors to assess the atmospheric deposition ofmetals in forested ecosystems in various regions of France. The concentrations of 17 metals/metalloids (Al, As, Cd, Co, Cr, Cs, Cu, Fe, Mn, Ni, Pb, Sb, Sn, Sr, Ti, V, and Zn) indicated overall lowatmospheric contamination in these forested environments, but a regionalism emerged fromlocal contributions (anthropogenic activities, as well as local lithology). Taking into account the geochemical background and comparing to Italian data, the elements from both natural and anthropogenic activities, such as Cd, Pb, or Zn, did not show any obvious anomalies. However, elements mainly originating from lithogenic dust (e.g., Al, Fe, Ti) were more prevalent in sparse forests and in the Southern regions of France, whereas samples from dense forests showed an accumulation of elements from biological recycling (Mn and Zn). The combination of enrichment factors and Pb isotope ratios between current and herbarium samples indicated the historical evolution of metal atmospheric contamination: the high contribution of coal combustion beginning 150 years ago decreased at the end of the 20th century, and the influence of car traffic during the latter observed period decreased in the last few decades. In the South of France, obvious local influences were well preserved during the last century

Bioaccumulation et bioindication par les lichens de la pollution atmosphérique actuelle et passée en métaux et en azote en France (sources, mécanismes et facteurs d'influence)

La contamination atmosphérique par les métaux/métalloïdes (As, Cd, Cu, Pb, Sb, Zn ) et par les composés azotés impacte durablement les écosystèmes. L évaluation des dépôts atmosphériques responsables de ces effets néfastes reste éparse car complexe, en particulier dans les environnements éloignés des sources de contamination comme les massifs forestiers. La prospection et l estimation des éléments traces et de l azote apportés dans ces dépôts ont été réalisées à l échelle nationale à travers deux approches de biosurveillance par les lichens et les mousses : la bioaccumulation et la bioindication. L enregistrement des éléments traces par les organismes indique une forte pression lithogénique dans ces milieux éloignés des sources directes, qui s inclut dans le bruit de fond géochimique (e. g. Al, As, Co, Cr, Fe, Ni et Ti). Des sources additionnelles issues des activités anthropiques plus locales complètent régionalement les cortèges des éléments chimiques enregistrés (Cd, Cu, Sb ou Zn). La comparaison des échantillons de lichens et de mousses avec des spécimens historiques d herbiers nous permet de retrouver ce contexte régional durant les siècles passés, et notamment de conforter les signatures lithologiques à travers le temps grâce aux terres rares. Ainsi, l utilisation du charbon fossile apparaît être la source de contamination métallique dominante durant la fin du XIX e siècle et le début du XX e siècle, et plus récemment, une source additionnelle comme le transport routier (cas de Pb) a pu être notée. En parallèle, des facteurs influençant la bioaccumulation des métaux ont été testés : l espèce considérée joue sur la capture des particules atmosphériques à travers la morphologie du thalle, et l écorce support ne présente que peu d influence. En considérant les signatures des dépôts atmosphériques, la végétation au travers des pluviolessivats apparaît influencer davantage les mousses terricoles que les lichens corticoles, ces derniers étant plus représentatifs des dépôts totaux. Des expérimentations de sorption/désorption montrent un processus rapide d accumulation (une semaine) pour Pb et Cd, mais ne montrent ni compétition entre les métaux bioaccumulés, ni influence du lessivage sur la bioaccumulation. De nouvelles données concernant la sensibilité des espèces lichéniques face aux polluants métalliques ont pu être obtenues à partir de relevés de bioindication couplés à des analyses statistiques multivariées.The atmospheric contamination by metals/metalloids (As, Cd, Cu, Pb, Sb, Zn ) and by nitrogen compounds impact the ecosystems. The atmospheric deposition is responsible of these harmful effects and its evaluation is complex and missing, particularly in remote environments like forest areas. The monitoring of trace element and nitrogen deposition at the national scale is carried out through two different approaches of biomonitoring by lichens and mosses: bioaccumulation and bioindication. The metal bioaccumulation points out a strong lithogenic pressure in these remote areas that is included in the geochemical background (e. g. Al, As, Co, Cr, Fe, Ni and Ti). Additional sources from more local anthropogenic activities are responsible for the regional context by the accumulation of other chemical elements (Cd, Cu, Sb or Zn). The comparison of current samples with herbarium specimens allows us getting back to historical regional influence one and half century ago, including consolidating the lithological influence over the time by rare earth elements. The use of fossil coal appears as a dominant source of metallic contamination in the late 19th century and the beginning 20th century. In parallel, the factors influencing the bioaccumulation of metals were evaluated: the entrapment of atmospheric particles is influenced by the morphology of the thallus but not by the bark. Considering the atmospheric deposition signature, vegetation via throughfall was found to be more influent for terricolous mosses than for corticolous lichens. Additional experiments of sorption/desorption showed a quick accumulation process (one week) for Pb and Cd, but neither metal competition, nor leaching influence on bioaccumulation were highlighted. New data on lichen species sensitivity to metal pollutants have been compiled through multivariate statistical analysisTOULOUSE-INP (315552154) / SudocSudocFranceF

Use of geochemical signatures, including rare earth elements, in mosses and lichens to assess spatial integration and the influence of forest environment

In order to assess the influence of local environment and spatial integration of Trace Metals (TM) by biomonitors, Al, As, Cd, Cr, Cs, Cu, Fe, Mn, Ni, Pb, Sb, Sn, V and Zn and some rare earth element (REE) concentrations have been measured in lichens and mosses collected in three French forest sites located in three distinct mountainous areas, as well as in the local soil and bedrock, and in both bulk deposition (BD) and throughfall (TF). Similar enrichment factors (EF) were calculated using lichens and mosses and local bedrock for most elements, except for Cs, Mn, Ni, Pb, and Cu which were significantly (KW, p < 0.05) more enriched in mosses. Similar REE ratios were measured in soils, bedrock, lichens and mosses at each study sites, indicating a regional integration of atmospheric deposition by both biomonitors. Both TM signature and REE composition of mosses revealed that this biomonitor is highly influenced by throughfall composition, and reflect atmospheric deposition interaction with the forest canopy. This explained the higher enrichment measured in mosses for elements which concentration in deposition were influenced by the canopy, either due to leaching (Mn), direct uptake (Ni), or dry deposition dissolution (Pb, Cu, Cs)

The SPLASH Action Group – Towards standardized sampling strategies in permafrost science

International audienceThe Action Group called ‘Standardized methods across Permafrost Landscapes: from Arctic Soils to Hydrosystems’ (SPLASH) is a community-driven effort aiming to provide a suite of standardized field strategies for sampling mineral and organic components in soils, sediments, and water across permafrost landscapes. This unified approach will allow data from different landscape interfaces, field locations and seasons to be shared and compared, thus improving our understanding of the processes occurring during lateral transport in circumpolar Arctic watersheds

Tundra uptake of atmospheric elemental mercury drives Arctic mercury pollution

Anthropogenic activities have led to large-scale mercury (Hg) pollution in the Arctic. It has been suggested that sea-salt-induced chemical cycling of Hg (through 'atmospheric mercury depletion events', or AMDEs) and wet deposition via precipitation are sources of Hg to the Arctic in its oxidized form (Hg(ii)). However, there is little evidence for the occurrence of AMDEs outside of coastal regions, and their importance to net Hg deposition has been questioned. Furthermore, wet-deposition measurements in the Arctic showed some of the lowest levels of Hg deposition via precipitation worldwide, raising questions as to the sources of high Arctic Hg loading. Here we present a comprehensive Hg-deposition mass-balance study, and show that most of the Hg (about 70%) in the interior Arctic tundra is derived from gaseous elemental Hg (Hg(0)) deposition, with only minor contributions from the deposition of Hg(ii) via precipitation or AMDEs. We find that deposition of Hg(0)-the form ubiquitously present in the global atmosphere-occurs throughout the year, and that it is enhanced in summer through the uptake of Hg(0) by vegetation. Tundra uptake of gaseous Hg(0) leads to high soil Hg concentrations, with Hg masses greatly exceeding the levels found in temperate soils. Our concurrent Hg stable isotope measurements in the atmosphere, snowpack, vegetation and soils support our finding that Hg(0) dominates as a source to the tundra. Hg concentration and stable isotope data from an inland-to-coastal transect show high soil Hg concentrations consistently derived from Hg(0), suggesting that the Arctic tundra might be a globally important Hg sink. We suggest that the high tundra soil Hg concentrations might also explain why Arctic rivers annually transport large amounts of Hg to the Arctic Ocean

Bioaccumulation and bioindication by lichens of the current and historical atmospheric pollution of metals and nitrogen in France : sources, mechanisms and influencing factors

La contamination atmosphérique par les métaux/métalloïdes (As, Cd, Cu, Pb, Sb, Zn…) et par les composés azotés impacte durablement les écosystèmes. L’évaluation des dépôts atmosphériques responsables de ces effets néfastes reste éparse car complexe, en particulier dans les environnements éloignés des sources de contamination comme les massifs forestiers. La prospection et l’estimation des éléments traces et de l’azote apportés dans ces dépôts ont été réalisées à l’échelle nationale à travers deux approches de biosurveillance par les lichens et les mousses : la bioaccumulation et la bioindication. L’enregistrement des éléments traces par les organismes indique une forte pression lithogénique dans ces milieux éloignés des sources directes, qui s’inclut dans le bruit de fond géochimique (e. g. Al, As, Co, Cr, Fe, Ni et Ti). Des sources additionnelles issues des activités anthropiques plus locales complètent régionalement les cortèges des éléments chimiques enregistrés (Cd, Cu, Sb ou Zn). La comparaison des échantillons de lichens et de mousses avec des spécimens historiques d’herbiers nous permet de retrouver ce contexte régional durant les siècles passés, et notamment de conforter les signatures lithologiques à travers le temps grâce aux terres rares. Ainsi, l’utilisation du charbon fossile apparaît être la source de contamination métallique dominante durant la fin du XIX e siècle et le début du XX e siècle, et plus récemment, une source additionnelle comme le transport routier (cas de Pb) a pu être notée. En parallèle, des facteurs influençant la bioaccumulation des métaux ont été testés : l’espèce considérée joue sur la capture des particules atmosphériques à travers la morphologie du thalle, et l’écorce support ne présente que peu d’influence. En considérant les signatures des dépôts atmosphériques, la végétation au travers des pluviolessivats apparaît influencer davantage les mousses terricoles que les lichens corticoles, ces derniers étant plus représentatifs des dépôts totaux. Des expérimentations de sorption/désorption montrent un processus rapide d’accumulation (une semaine) pour Pb et Cd, mais ne montrent ni compétition entre les métaux bioaccumulés, ni influence du lessivage sur la bioaccumulation. De nouvelles données concernant la sensibilité des espèces lichéniques face aux polluants métalliques ont pu être obtenues à partir de relevés de bioindication couplés à des analyses statistiques multivariées.The atmospheric contamination by metals/metalloids (As, Cd, Cu, Pb, Sb, Zn…) and by nitrogen compounds impact the ecosystems. The atmospheric deposition is responsible of these harmful effects and its evaluation is complex and missing, particularly in remote environments like forest areas. The monitoring of trace element and nitrogen deposition at the national scale is carried out through two different approaches of biomonitoring by lichens and mosses: bioaccumulation and bioindication. The metal bioaccumulation points out a strong lithogenic pressure in these remote areas that is included in the geochemical background (e. g. Al, As, Co, Cr, Fe, Ni and Ti). Additional sources from more local anthropogenic activities are responsible for the regional context by the accumulation of other chemical elements (Cd, Cu, Sb or Zn). The comparison of current samples with herbarium specimens allows us getting back to historical regional influence one and half century ago, including consolidating the lithological influence over the time by rare earth elements. The use of fossil coal appears as a dominant source of metallic contamination in the late 19th century and the beginning 20th century. In parallel, the factors influencing the bioaccumulation of metals were evaluated: the entrapment of atmospheric particles is influenced by the morphology of the thallus but not by the bark. Considering the atmospheric deposition signature, vegetation via throughfall was found to be more influent for terricolous mosses than for corticolous lichens. Additional experiments of sorption/desorption showed a quick accumulation process (one week) for Pb and Cd, but neither metal competition, nor leaching influence on bioaccumulation were highlighted. New data on lichen species sensitivity to metal pollutants have been compiled through multivariate statistical analysi

Les lichens épiphytes : sentinelles de la qualité de l'air

Organismes symbiotiques entre un champignon et une algue, les lichens sont présents partout avec 20 000 espèces à travers le monde. Du fait de leur caractéristiques biologiques, ils constituent de précieux témoins de la qualité de l’air. Ils sont fréquemment employés pour évaluer, à faible coût, les niveaux de contamination d’un environnement donné, depuis les milieux urbains jusqu’aux écosystèmes forestiers. Cela nécessite néanmoins la mise en place de protocoles adaptés pour chaque type d’écosystème et un suivi régulier afin d’identifier tout changement dynamique