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Foram estudados o sulfeto volatilizado em meio ácido (AVS), os metais simultaneamente extraídos (SEM) e os metais em sítios de sedimentos do Estuário do Rio Sergipe, Brasil. As concentrações de AVS e SEM foram, em geral, maiores nos sedimentos dos sítios situados nas áreas que recebem maior aporte antrópico devido à poluição urbana. Nesses sítios, o sulfeto parece ser a principal fase de ligação para os metais. No sítio do sedimento situado na área de maior influência marinha, as fases mais importantes de ligação para os metais parecem estar associadas à matéria orgânica e aos carbonatos. Os perfis de AVS permitiram identificar dois tipos de processos de sedimentação no estuário. Em todos os sítios, as relações SEM/AVS foram muito menores do que 1. Acid volatile sulfide (AVS), simultaneously extracted metals (SEM) and metals were studied in sediment cores from the Sergipe River Estuary, Brazil. AVS and SEM concentrations were, in general, higher in the core sediments from areas which receive a higher anthropic contribution due to urban pollution. In these cores, the sulfide seemed to be the main connection for the metals. In the core obtained from the area of major marine influence, the most important binding phases for the metals seemed to be associated with organic matter and carbonates. The AVS profiles allow identification of two types of sedimentation processes in the estuary. In all cores SEM/AVS ratios were much lower than 1.

O procedimento de extração seqüencial proposto pelo European Community Bureau of Reference (BCR) foi empregado para o fracionamento de Cd, Cr, Cu, Ni, Pb e Zn em sedimentos do estuário do Rio Sergipe, Brasil. O método empregado apresentou-se adequado com limite de detecção e desvio padrão aceitável para a determinação de metais em amostras de sedimentos. Cd foi o metal com maior percentagem na fração extraível. Ni e Pb estão presentes principalmente nas frações oxidável e redutível. Cr, Cu e Zn foram encontrados predominantemente na fração residual. A ordem de mobilidade dos metais extraídos foi Pb > Cd > Ni > Cu > Cr > Zn. De acordo com o código de avaliação de risco (RAC), as amostras de sedimentos mostraram risco baixo a médio para todos os metais analisados.The sequential extraction procedure proposed by the European Community Bureau of Reference (BCR) was applied for the fractionation of Cd, Cr, Cu, Ni, Pb and Zn in sediments from the Sergipe Estuary, Brazil. The method showed satisfactory recoveries, detection limits and standard deviations for trace metals determinations in sediment samples. Cd was the metal with the greatest percentage in the exchangeable fraction. Pb and Ni were present mainly in the reducible and oxidizable fractions. Cr, Cu and Zn were predominantly associated with the residual fraction. The order of mobility of metals extracted was Pb > Cd > Ni > Cu > Cr > Zn. According to the risk assessment code (RAC), the sediments showed low to medium risk for all metals.

Cd, Co, Cr, Cu, Mn, Ni, Zn, and Pb were measured in feather samples of adult, subadult, and juvenile of Larus dominicanus, sampled in the Florianólis, SC, in the south of Brazil in December 2005, by flame atomic absorption spectrophotometry. The average of the distribution of Cd concentration in adult feathers (0.072 microg g(-1)) was significantly different than that found in juvenile feathers (0.021 microg g(-1)). Cu concentration averages were not significantly different between adults (13.30 microg g(-1)), subadults (9.67 microg g(-1)), and juveniles (13.76 microg g(-1)). For adults and juveniles there was significant difference in feather concentrations for Cd, Co, Cr, Ni, and Pb. The distribution of Mn concentration averages in feathers differs between adults (11.36 microg g(-1)) and juveniles (1.184 microg g(-1)). Ni concentration averages of adults (5.92 microg g(-1)) were significantly higher than those of juveniles (2.23 microg g(-1)). For Pb, concentration averages were significantly higher in adults (7.53 microg g(-1)) than in juveniles (1.47 microg g(-1)). The concentration of Co and Cr in juvenile and subadults are statistically different when compared with the adults. In the present study, levels of Cd, Co, Cr, Mn, Ni, Zn, and Pb increased with age. The concentrations of essential trace elements in L. dominicanus were generally comparable to values reported in other studies. With non-essential metals (Cd, Pb, and Ni), in our study, L. dominicanus had lower values than those reported for their northern Atlantic counterparts.

A sub-bacia hidrográfica do rio Poxim é formada por quatro rios de água doce, Poxim-Açu, Poxim-Mirim, Poxim e Pitanga e está situada na porção leste do Estado de Sergipe, Nordeste do Brasil. Nesse trabalho foi investigada a distribuição, os fatores que controlam as concentrações e o risco de toxicidade para Co, Cr, Cu, Li, Mn, Ni, Pb, Zn, Al e Fe em sedimentos superficiais dos quatro rios. A toxicidade foi avaliada usando o Consensus-based Sediment Quality Guidelines for freshwater ecosystems. A matriz de Spearman não indicou associação dos metais com a matéria orgânica, mas mostrou uma forte correlação com alumínio, moderada com o ferro e fraca com o manganês, sugerindo ser as argilas os principais carreadores dos metais para os sedimentos. Em todas as amostras as concentrações dos metais ficaram abaixo do TEC (threshold effect concentration) indicando que em relação aos metais traço, raramente deve ocorrer efeito adverso para a biota aquática. Foi definida uma base geoquímica para a região usando o lítio como elemento de referência. Somente em três sítios foram observados enriquecimentos dos metais associados a influências antrópicas. Os valores do fator de enriquecimento sugerem uma grande predominância nos sedimentos, de metais de origem natural.The Poxim river hydrographic sub-basin comprises four freshwater rivers, Poxim-Açu, PoximMirim, Poxim and Pitanga, and is located in the East of Sergipe State, Northeast of Brazil. The present work investigates the distribution, the factors controlling concentrations, and toxicity risks of the metals Co, Cr, Cu, Li, Mn, Ni, Pb, Zn, Al and Fe, in surface sediments of the four rivers. Toxicity was evaluated using the Consensus-based Sediment Quality Guidelines for freshwater ecosystems. Spearman correlation analysis did not indicate any association of the metals with organic matter, however strong, moderate and weak correlations with aluminium, iron, and manganese, respectively, suggested that clay minerals were the main carrier of metals to sediments. Concentrations of metals in all samples were below the TEC (threshold effect concentration), indicating that for these trace metals adverse effects on aquatic biota should rarely occur. A geochemical baseline for the region was defined using lithium as reference element. Metal enrichments due to anthropogenic influence were only observed at three sites. At other sites, enrichment factors were indicative of a large predominance of naturally occurring metals in the sediments. Keywords: sediments, trace metals, geochemical baselines, Poxim River IntroductionAquatic sediments accumulate metals derived from both natural processes as well as anthropogenic activities, and play a fundamental role in redistribution of these elements to water and aquatic biota. The ability to accumulate and redistribute chemical species makes sediments extremely interesting for the purposes of environmental investigation, since they can provide a semi-permanent record of levels of contamination. [1][2][3] In order to determine the contamination de...

This paper presents the distributions of the investigation of trace metals geochemistry in surface sediments of the Sergipe river estuary, northeast Brazil. Analyses were carried out by Flame or electrothermal atomic absorption spectrometry (FAAS or ETAAS). Principal component analysis was applied to results to identify any groupings among the different sampling sites. In order to determine the extent of contamination, taking into account natural variability within the region, metal concentrations were normalized relative to aluminium. Cr, Cu, Ni and Zn contamination was observed in sediments from the area receiving highest inputs of domestic wastes, while cadmium contamination occurred in sediments from the region affected by highest inflows of industrial effluents. Possible toxicity related to these metals was examined using the relationship simultaneously extracted metals/acid volatile sulfide and by comparing sediment chemical data with sediment quality guidelines ERL-ERM values. Results obtained using the two methods were in agreement and indicated that adverse effects on aquatic biota should rarely occur.

The concentrations of cadmium, copper, nickel, zinc, and lead were determined in the catfish (Cathorops spixii) from the Sal River estuary, Brazil, to evaluate the potential role of domestic and industrial effluents released without treatment on the quality of the estuarine environment with consequences to fish resources. Muscle, liver, and kidney samples were analyzed for trace metal composition by flame atomic absorption spectrophotometry. The mean concentration (µg/g wet weight) of trace metals in the tissues of C. spixii were as follows: cadmium = 1.65, 2.81, and 0.71 µg/g; copper = 29.07, 4.38, and 3.40 µg/g; zinc = 229, 312, and 15.57 µg/g; nickel = 1.22, 1.04, and 117 µg/g; and lead = 7.09, 10.77, and 11.18 µg/g. The results show that metal accumulation in organs indicates the difference between them. The results showed high concentrations of copper, zinc, nickel, lead, and cadmium in the Cathorops spixii compared with the maximum values registered from fish in studies reported in other coastal regions of Brazil.

Surface sediments from the River São Francisco were analyzed to investigate the impact, due to the presence of metals (Cd, Cu, Pb, Zn) in wastes from a metallurgical industry in the city of Três Marias/MG, Brazil. The concentrations and geochemical associations of Pb, Zn and trace metals associated with the minerals employed in zinc production were measured. Sediments close to discharge locations were highly contaminated with Pb (332-512 µg g , with values decreasing rapidly due to dilution and hydraulic sorting. Evaluation of toxicity according to the Consensus-based Sediment Quality Guidelines indicated for Cd, Pb and Zn a high probability of adverse effects on aquatic biota at these sites.Keywords: contaminated sediment; lead; zinc. INTRODUÇÃOAtividades de mineração e exploração comercial de recursos minerais fazem parte do conjunto das atividades humanas que mais têm contribuído para introdução de metais traço na hidrosfera. Os rejeitos dessas atividades contêm concentrações elevadas de metais e, por causa da instabilidade química e geotécnica desses materiais, representam, por longo tempo, uma fonte potencial de contaminação. [1][2][3] A contaminação de sedimentos com metais derivados de efluentes da mineração e do beneficiamento de minérios têm se tornado um problema global 4 e, por isso, tem adquirido muita importância a avaliação geoquímica desses sedimentos, no sentido de diferenciar o metal derivado daquelas fontes de contaminação daquele originário do background regional e de fontes difusas globais. 5,6 Tem também sido destacada a necessidade de se entender os processos de dispersão dos metais pelo transporte fluvial, pois isso pode contribuir para melhorar as práticas de gerenciamento dos rios contaminados. Os sedimentos agem como um reservatório no qual as espécies quí-micas são acumuladas no decorrer do tempo e, desse modo, se constituem num arquivo útil para avaliação de contaminações passadas. Uma parte significativa dos metais introduzidos no rio por algum aporte, transiente ou contínuo, deve se acumular nos sedimentos através de processos químicos e físicos de sorção.1 Vários estudos têm documentado concentrações extremamente elevadas de Pb, Zn e Cd em sedimentos próximos a áreas de mineração, inclusive com a ocorrência de efeitos ecológicos adversos, provocados pelos metais associados aos sedimentos. Nessas mesmas áreas tem também sido registrado aumento das concentrações de metais (Pb, Zn, Cd) em invertebrados aquáticos e peixes. 8-11As concentrações naturais dos elementos traço em sedimentos são fortemente determinadas pela natureza do material inorgânico resultante do intemperismo físico e químico. Esse material é formado principalmente por um número limitado de silicatos, tais como quartzo, feldspato, micas e argilas minerais, e em menor quantidade por óxi-dos metálicos e sulfetos. Entre os diferentes substratos geoquímicos que compõem os sedimentos, os mais importantes são aqueles que detêm a capacidade de reter e concentrar elementos traço e nesse caso destacam-se os compostos argilomine...