Temporal and spatial bioassessment of ecological risk of Amazonian Itchyofauna associated to Hg exposure

In Amazon artisan gold mining, mercury (Hg) is released to environment during its use to amalgamate the fine particles of gold. Once mercury entries in aquatic ecosystems, it might be methylated to methylmercury (MeHg). The objectives of this work were: (i) to establish and compare the dose-response relationship for Hg accumulation by Tucunaré for a contaminated and a background area; (ii) to test the DRAC methodology to proceed field sampling of fish; (iii) to conduct a temporal analysis of magnitude of mercury contamination in fish during the last decade by using DRAC methodology and (v) to investigate the relationship between hematological parameters (erythrocytes, hematocrit, leukocytes and mean corpuscular volume) and Hg exposure in fish.. Close to 100 Tucunarés were caught in the Tapajós River region. The results showed significant differences in hematological parameters and Hg concentration considering contaminated and background areas and the temporal assessment suggest increase the Hg bio-availability during last decade in Tapajos River Region. One could suggest that those hematological parameters might be used as physiological biomarkers of Hg exposure in ecological risk assessment process and that Hg used by or remaining from gold mining “garimpos” might be continuous bio-available to Amazonian biota

Evaluation of trace metals (cadmium, chromium, copper and zinc) in tissues of a commercially important fish (Leporinus obtusidens) from Guaíba Lake, Southern Brazil

Concentrations of Cd, Cr, Cu and Zn were determined in liver and muscle of Leporinus obtusidens. During 2003, the fishes (N = 54) were sampled from three sites along Guaíba Lake (north, central and south zones). The hypotheses tested assumed that there were differences in the location and date as to levels of contamination, association between the trace metal content in the fishes and size, and that the sex influenced metal accumulation. Possible risks of contaminated fish consumption to human health were also evaluated. The level of mean concentration (µg/g) of metals in tissues was higher in liver than muscle: [Cd] = 2.32&#9794;; [Cr] = 0.08&#9792;; [Cu] = 30.82&#9792; and [Zn] = 97.77&#9792;. The results showed differences between the local and date sampling for all metals except Cr. Metal content was higher in the warmer than colder seasons and in the central zone than at other points. Significant sexual differences were detected for Cd and Zn and there were positive associations between the size and metal concentrations for Cu and Zn. The concentration levels of metals in muscle tissue showed that the fish samples did not offer risks to human health.<br>As concentrações dos metais Cd, Cr, Cu e Zn foram determinadas para os tecidos muscular e hepático de Leporinus obtusidens no sul do Brasil. Durante o ano de 2003, 54 indivíduos foram capturados em três locais ao longo do Lago Guaíba (norte, centro e sul). Neste estudo verificamos se havia diferenças entre os locais de amostragem e as épocas do ano nas concentrações de metais nos tecidos analisados, bem como relação entre a concentração do metal e tamanho e sexo dos indivíduos. O risco para o consumo humano também foi avaliado. A concentração média (µg/g) dos metais foi maior no fígado do que no músculo para todos os metais: [Cd] = 2,32&#9794;; [Cr] = 0,08&#9792;; [Cu] = 30,82&#9792; e [Zn] = 97,77&#9792;. Os resultados apresentaram diferenças significativas entre os locais (região central do lago com as maiores concentrações) e épocas do ano (meses de primavera e verão) para todos os metais, exceto Cr. Diferenças entre os sexos também foram detectadas, para Cd e Zn, e relações com o tamanho dos indivíduos para Cu e Zn. Os níveis encontrados no tecido muscular não oferecem riscos ao consumo da espécie