A dinamica biogeoquimica do mercurio na bacia do Rio Negro (AM) e fluxos na interface agua/atmosfera

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

The biogeochemistry of mercury, including the evaluation of Dissolved Gaseous Mercury (DGM) fluxes at the interface water/air in the Rio Negro basin was carried out assuming four different approaches: (a) measurements of total mercury in the atmosphere and in the total precipitation, as well as total, reactive and dissolved gaseous mercury in the surface waters; (b) diel estimates of DGM fluxes in both black and white waters; (c) in situ photochemical experiments using both types of waters, and (d) integrated approach using analytical results and sub-basin tributaries characteristics were perfomed with Geographic Information System (GIS) and Remote Sensing (RS). This approach allowed to generate a model for the DGM flux at the water/air interface, as well as to subsidize the proposal of a general model of mercury cycling in the Rio Negro basin. From the obtained results, it is important to point out the existence of photoreducting and photooxidizing mechanisms in black waters, being the oxidative mechanisms promoted by OH radical and H2O2 generated by Fenton s reaction due to the high amount of dissolved organic matter. DGM fluxes were around 2.2 pmol m h and the total mercury mass exported at the water/air interface was 0,26 ton y. Average value for the total mercury deposition over the Rio Negro 18 tributaries sub-basins was 22,9 mg m y. It is also important to mention that mercury has been accumulating in the basin at rates of 13,4 ton y, being the metal retention directly associated with the type soil present in the basin.

ASSUNTO(S)

amazonia sistema de informação geografica mercurio

ACESSO AO ARTIGO

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