title: Environmental and Anthropogenic Factors Influencing Mercury Dynamics During the Past Century in Floodplain Lakes of the Tapajós River, Brazilian Amazon.
abstract: In the Tapajós River region of the Brazilian Amazon, mercury (Hg) is a prevalent contaminant in the aquatic ecosystem. Few studies have used comprehensive chronological analyses to examine the combined effects of environmental and anthropogenic factors on Hg accumulation in sediments. Total mercury (THg) content was measured in sediments from eight floodplain lakes andPb210 isotope analysis was used to develop a timeline of THg accumulation. Secondary data representing environmental and anthropogenic factors were analyzed using geo-spatial analyses. These include land-cover change, hydrometeorological time-series data, lake morphology, and watershed biophysical characteristics. The results indicate that THg accumulation and sedimentation rates have increased significantly at the surface of most sediment cores, sometimes doubling since the 1970s. Human-driven land-cover changes in the watershed correspond closely to these shifts. Tropical deforestation enhances erosion, thereby mobilizing the heavy metal that naturally occurs in soils. Environmental factors also contribute to increased THg content in lacustrine sediments. Climate shifts since the 1980s are further compounding erosion and THg accumulation in surface sediments. Furthermore, variations in topography, soil types, and the level of hydrological connectivity between lakes and the river explain observed variations in THg fluxes and sedimentation. Although connectivity naturally varies among sampled lakes, deforestation of sensitive floodplain vegetation has changed lake-river hydrology in several sites. In conclusion, the results point to a combination of anthropogenic and environmental factors as determinants of increased THg accumulation in tropical floodplain sediments in the Tapajós region.
authors.affiliation: Centro de Desenvolvimento Sustentável (CDS), Universidade de Brasília, Campus Universitário Darcy Ribeiro, Gleba A, Asa Norte, Brasília, DF, 70910-900, Brazil. jsoestreicher@gmail.com.|Institut des sciences de l'environnement (ISE), Université du Québec à Montréal, Montreal, Canada. jsoestreicher@gmail.com.
authors.forename: Jordan Sky
authors.identifier: http://orcid.org/0000-0001-7576-7706
authors.initials: JS
authors.lastname: Oestreicher
authors.affiliation: Institut des sciences de l'environnement (ISE), Université du Québec à Montréal, Montreal, Canada.|Centre de recherche GEOTOP, Université du Québec à Montréal, Montreal, Canada.
authors.forename: Marc
authors.initials: M
authors.lastname: Lucotte
authors.affiliation: Institut des sciences de l'environnement (ISE), Université du Québec à Montréal, Montreal, Canada.|Centre de recherche GEOTOP, Université du Québec à Montréal, Montreal, Canada.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Moingt
authors.affiliation: Institut des sciences de l'environnement (ISE), Université du Québec à Montréal, Montreal, Canada.
authors.forename: Émilie
authors.initials: É
authors.lastname: Bélanger
authors.affiliation: Institut des sciences de l'environnement (ISE), Université du Québec à Montréal, Montreal, Canada.
authors.forename: Christine
authors.initials: C
authors.lastname: Rozon
authors.affiliation: Biodôme de Montréal, Montreal, Canada.
authors.forename: Robert
authors.initials: R
authors.lastname: Davidson
authors.affiliation: Centro de Desenvolvimento Sustentável (CDS), Universidade de Brasília, Campus Universitário Darcy Ribeiro, Gleba A, Asa Norte, Brasília, DF, 70910-900, Brazil.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Mertens
authors.affiliation: Centro de Desenvolvimento Sustentável (CDS), Universidade de Brasília, Brasília, Brazil.|Université Paris Descartes, Paris, France.
authors.forename: Christina A
authors.initials: CA
authors.lastname: Romaña
mesh_terms: D001938:Brazil; D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000032:analysis*; D060106:Lakes / Q000737:chemistry; D008628:Mercury / Q000032:analysis*; D045483:Rivers; D012621:Seasons; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D014874:Water Pollutants, Chemical; D008628:Mercury