Biomonitoring of trace metal elements by lichens of the Western Pyrenees.Study of elemental and isotopic signature of mercury

Abstract

The lichens, organisms originated by symbiotic relationship between an algae and a fungus, have shown good properties as biomonitors of pollution from Trace Metal Elements. They can be used as indicators of local and long-range atmospheric pollution. The assessment of deposition of atmospheric pollutants results difficult to know their long term impact. This happens specially when the study is focalized in remote areas. In this project it has been developed the elemental and isotopic analysis of mercury composition (and lead that will be carried out after presentation of this report) on epiphytic lichens (growing on tree barks). The samples were collected in the mountain ecosystem of Iraty Forest, on both sides of the border between France (Departement des Pyrénées Atlantiques) and Spain (Comunidad de Navarra). The determination of different trace metal elements (by ICP-MS Analysis) present in the lichens can be used to asses the spatial distribution of this pollutants all over the study area. The new analytical methodology (Multi-Collection Analysis coupled with ICP-MS) used for isotopic analysis allow to a better discrimination or “fingerprinting” of the pollution sources and environmental pathways followed by mercury in mountain ecosystems.