title: Total mercury and methyl-mercury contents and accumulation in polar microbial mats.
abstract: Although polar regions are considered isolated and pristine areas, the organisms that inhabit these zones are exposed to global pollution. Heavy metals, such as mercury, are global pollutants and can reach almost any location on Earth. Mercury may come from natural, volcanic or geological sources, or result from anthropogenic sources, in particular industrial or mining activities. In this study, we have investigated one of the most prominent biological non-marine communities in both polar regions, microbial mats, in terms of their Hg and methyl-mercury (MeHg) concentrations and accumulation capacities. The main hypotheses posed argued on the importance of different factors, and to test them, we have measured Hg concentrations in microbial mats that were collected from 6 locations in different ecological situations. For this purpose, the direct anthropogenic impacts, volcanic influences, proximity to the seashore, latitudinal gradients and C contents were investigated. Our results show that, other than the direct anthropogenic influence, none of the other hypotheses alone satisfactorily explains the Hg content in microbial mats. In contrast, the MeHg contents were noticeably different between the investigated locations, with a higher proportion of MeHg on the McMurdo Ice Shelf (Antarctica) and a lower proportion on Ward Hunt Island (High Arctic). Furthermore, our results from in situ experiments indicated that the microbial mats from South Shetland Islands could quickly accumulate (48 h) Hg when Hg dissolved salts were supplied. Over short-term periods, these mats do not transform Hg into MeHg under field conditions.
authors.affiliation: Instituto Cavanilles de Biodiversidad y Biología Evolutiva and Departamento de Microbiología y Ecología, Edificio de Investigación, Campus de Burjassot, Universitat de Valencia, E-46100 Burjassot, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Camacho
authors.affiliation: Instituto Cavanilles de Biodiversidad y Biología Evolutiva and Departamento de Microbiología y Ecología, Edificio de Investigación, Campus de Burjassot, Universitat de Valencia, E-46100 Burjassot, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Rochera
authors.affiliation: Laboratoire de Glaciologie et Géophysique de l'Environnement-CNRS UMR 5183, 54, rue Molière, Domaine Universitaire, B.P. 96, Université Joseph Fourier-Grenoble 1 F-38402, Saint Martin d'Hères, France.
authors.forename: Raphaëlle
authors.initials: R
authors.lastname: Hennebelle
authors.affiliation: Laboratoire de Glaciologie et Géophysique de l'Environnement-CNRS UMR 5183, 54, rue Molière, Domaine Universitaire, B.P. 96, Université Joseph Fourier-Grenoble 1 F-38402, Saint Martin d'Hères, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Ferrari
authors.affiliation: Departamento de Biología, Universidad Autónoma de Madrid, E-28049, Madrid, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Quesada
mesh_terms: D001110:Arctic Regions; D018441:Biofilms; D004784:Environmental Monitoring; D008628:Mercury / Q000032:analysis*; D008767:Methylmercury Compounds / Q000032:analysis*; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical; C073972:dimethyl mercury; D008628:Mercury
keywords: Antarctica; High Arctic; Mercury; Methyl-mercury; Microbial mats; Polar regions