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Mercury net methylation in five tropical flood plain regions of Brazil: high in the root zone of floating macrophyte mats but low in surface sediments and flooded soils

Guimarães, Jean Remy Davée ; Meili, Markus ; Hylander, Lars Daniel ; Silva, Edinaldo de Castro e ; Roulet, Marc ; Mauro, Jane Beatriz Narvaez ; de Lemos, Romilda Alves Lindberg, S ; Levin, L ; Porcella, D (eds)

The Science of the total environment, 2000-10, Vol.261 (1), p.99-107 [Periódico revisado por pares]

Shannon: Elsevier B.V

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Mercury net methylation in five tropical flood plain regions of Brazil: high in the root zone of floating macrophyte mats but low in surface sediments and flooded soils
Autor: Guimarães, Jean Remy Davée ; Meili, Markus ; Hylander, Lars Daniel ; Silva, Edinaldo de Castro e ; Roulet, Marc ; Mauro, Jane Beatriz Narvaez ; de Lemos, Romilda Alves
Lindberg, S ; Levin, L ; Porcella, D (eds)
Assuntos: Amazon ; Animal, plant and microbial ecology ; Applied ecology ; Applied sciences ; Biological and medical sciences ; Biological and physicochemical phenomena ; Biological and physicochemical properties of pollutants. Interaction in the soil ; Brazil ; Disasters ; Earth sciences ; Earth, ocean, space ; Ecotoxicology, biological effects of pollution ; Engineering and environment geology. Geothermics ; Exact sciences and technology ; Floating macrophyte mats ; Floodplain ; Fresh water environment ; Fundamental and applied biological sciences. Psychology ; Geologic Sediments - chemistry ; Mercury ; Mercury - analysis ; Mercury - metabolism ; Methylation ; Methylmercury ; Methylmercury Compounds - analysis ; Natural water pollution ; Plant Roots - chemistry ; Pollution ; Pollution, environment geology ; Soil and sediments pollution ; Tissue Distribution ; Water Pollutants, Chemical - analysis ; Water treatment and pollution
É parte de: The Science of the total environment, 2000-10, Vol.261 (1), p.99-107
Notas: ObjectType-Article-2
SourceType-Scholarly Journals-2
ObjectType-Feature-1
content type line 23
SourceType-Conference Papers & Proceedings-1
ObjectType-Conference-3
Descrição: In aquatic systems, bottom sediments have often been considered as the main methylmercury (MeHg) production site. In tropical floodplain areas, however, floating meadows and flooded forests extend over large areas and can be important Hg methylating sites. We present here a cross-system comparison of the Hg net methylation capacity in surface sediments, flooded soils and roots of floating aquatic macrophytes, assayed by in situ incubation with 203Hg and extraction of formed Me 203Hg by acid leaching and toluene. The presence of mono-MeHg was confirmed by thin layer chromatography and other techniques. Study areas included floodplain lakes in the Amazon basin (Tapajós, Negro and Amazon rivers), the Pantanal floodplain (Paraguay river basin), freshwater coastal lagoons in Rio de Janeiro and oxbow lakes in the Mogi-Guaçú river, São Paulo state. Different Hg levels were added in assays performed in 1994–1998, but great care was taken to standardise all other test parameters, to allow data comparisons. Net MeHg production was one order of magnitude higher (mean 13.8%, range 0.28–35) in the living or decomposing roots of floating or rooted macrophyte mats ( Eichhornia azurea, E. crassipes, Paspalum sp., Eleocharis sellowiana, Salvinia sp., S. rotundifolia and Scirpus cubensis) than in the surface layer of underlying lake sediments (mean 0.6%, range 0.022–2.5). Methylation in flooded soils presented a wide range and was in some cases similar to the one found in macrophyte roots but usually much lower. In a Tapajós floodplain lake, natural concentrations of MeHg in soil and sediment cores taken along a lake–forest transect agreed well with data on net methylation potentials in the same samples. E. azurea, E. crassipes and Salvinia presented the highest methylation potentials, up to 113 times higher than in sediments. Methylation in E. azurea from six lakes of the Paraguay and Cuiabá rivers, high Pantanal, was determined in the 1998 dry and wet seasons and ranged from 1.8 to 35%. Methylation was lower in washed roots than in untreated roots of E. azurea and methylation in solids isolated from the roots, was higher than in sediments but lower than in untreated roots. This indicates that the methylation in roots zones occurs mainly in the root-associated solids. Floating meadows are sites of intense production of biomass and of highly bioavailable MeHg and appear to be an essential link of the MeHg cycle in tropical aquatic systems.
Editor: Shannon: Elsevier B.V
Idioma: Inglês

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Mercury net methylation in five tropical flood plain regions of Brazil: high in the root zone of floating macrophyte mats but low in surface sediments and flooded soils

Guimarães, Jean Remy Davée ; Meili, Markus ; Hylander, Lars Daniel ; Silva, Edinaldo de Castro e ; Roulet, Marc ; Mauro, Jane Beatriz Narvaez ; de Lemos, Romilda Alves Lindberg, S ; Levin, L ; Porcella, D (eds)

Shannon: Elsevier B.V

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