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Spatio‐temporal geochemistry of mercury in waters of the Tapajós and Amazon rivers, Brazil
Author(s) -
Roulet M.,
Lucotte M.,
Canuel R.,
Farella N.,
De Freitos Goch Y. G.,
Pacheco Peleja J. R.,
Guimarães J.-R. D.,
Mergler D.,
Amorim M.
Publication year - 2001
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.2001.46.5.1141
Subject(s) - methylmercury , tributary , mercury (programming language) , environmental science , amazon rainforest , aquatic ecosystem , environmental chemistry , hydrology (agriculture) , drainage basin , water column , soil water , ecosystem , surface water , ecology , oceanography , bioaccumulation , geology , chemistry , geography , environmental engineering , soil science , biology , cartography , geotechnical engineering , computer science , programming language
Spatial and temporal variations of mercury (Hg) concentrations were monitored in the surface waters from the lower portion of the Tapajós River, the Arapiuns River, its principal tributary, and the Amazon River at its confluence with the Tapajós. In the rivers, Hg concentrations in the water column are governed by the concentration of suspended particles. Hg in the filtered water showed very little seasonal variation with low concentrations in the lower Tapajós (<1.8 ng L −1 ), Arapiuns (<0.8 ng L −1 ), and Amazon (<2.8 ng L −1 ). Concentrations of fine particulate Hg (0.6–29.7 ng L −1 ) represent 40%–90% of the total volumetric concentration of Hg. In relation to their oxyhydroxide contents, suspended particles are not richer in Hg than nearby soils where oxyhydroxides control the accumulation of Hg. The study shows that the dominant stock of Hg in the aquatic ecosystems of this region is derived from erosion of natural soils in the catchment rather than from anthropogenic pollution. The input of natural Hg coming from soils into the aquatic ecosystems may have increased over historical levels in the region. This increase of total Hg in aquatic ecosystems could potentially account for high levels of methylmercury recently reported in fish and humans in the lower Tapajós River area, but the link between the different processes that promote high levels of methylmercury exposure for the human community remains to be proved.