AvaliaÃÃo das concentraÃÃes de elementos quÃmicos nos sedimentos de fundo do estuÃrio do Rio Formoso (PE)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The estuary of Formoso river is located in the south coastal zone of the Pernambuco state, in an environmental protection area, named APA of Guadalupe. This is an important coastal ecosystem with a rich biodiversity, which plays an important socioeconomic role for the local population. Anthropogenic activities such as shrimp farming, sugar cane cultivation, urban effluents, and landfills were observed in the area. In order to provide the assessment of the contamination levels in this estuary, concentrations of several chemical elements (Li, Be, Mg, Al, K, V, Cr, Fe, Mn, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Mo , Cd, Sb, Ba, Tl, Pb, and Ca) in samples of bottom sediments. The silt-clay fraction (<63μm) of the sediments were used for the analyses. The chemical extraction was performed with HCl 0.5M and the determination was made by ICP-MS. The results indicate the concentrations of chemical elements considered susceptive to the bioavailability, and they were compared with the reference values of the Canadian and North American environmental agencies, as well as with those of other estuaries from northeastern Brazil and worldwide, and the average of the shale composition in the world. Relative high concentrations of As (2.4-20mg Kg-1) were found, and this metalloid should be as As (V) (arsenate) in the estuarine water, according to its Eh-pH conditions. At the estuary of Formoso river, As may be of anthropogenic origin, as suggest the close spatial relationship with landfills, agricultural activities, and poultry. The Fe concentrations (3,675-21,807mg kg-1) were higher than those found in Brazilian and worldwide estuaries. Positive correlations found between Zn-Cr-Pb and Fe-Al-Mn-organic matter reveal that probably these metals occur in Fe and Mn oxy-hydroxides, and/or adsorbed in clay minerals, and/or in organometallic complexes. Another positive correlation was observed between Co-Ni and As-Cd-Tl, which seems to be unusual in terms of natural geochemical associations, and thus can indicate that at least As, Cd, and Tl could be from anthropogenic sources. The estuary of Formoso river is considered a well preserved site, but concentrations of chemical elements reported in this work indicate that it need to be monitored

ASSUNTO(S)

geociencias fontes de contaminaÃÃo sedimentos estuarinos estuÃrio do rio formoso estuarine sediment chemical elements sources of contamination elementos quÃmicos estuary of the formoso river

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