Ecotoxicologia do mercúrio total em peixes do hidrossistema da UHE Curuá-Una.

Abstract

The heavy metals as mercury (Hg) is considered the most toxic and poses a great risk to the environment. In addition to its high toxicity, mercury contamination is widely discussed with respect to two important processes that it undergoes in contaminated organisms: bioaccumulation and bioconcentration. Fish are good indicators of Hg contamination and in reservoirs these have presented high levels of contamination, mainly carnivores. Fish collected downstream from the dams have demonstrated higher Hg levels than the amount. In the Amazon region, the main route of exposure to mercury is fish consumption, especially by riverine communities. The hydroelectric reservoirs of Curuá-Una, inaugurated in 1977, was the first dam built in the Central Amazon, which is our area of study. The objective of this work was to examine the concentrations of total mercury in fish muscle tissues at different collection points in the Curuá-Una Santarém/PA HPP. The fish samples were collected in September 2011, during the river ebbing period. Samples of the ichthyofauna occurred at nine collection points, seven upstream of the dam and nine downstream, on the Curuá-Una river. The water, sediment and fish samples were analyzed by Cold Vapor Atomic Fluorescence Spectrometry-CVAFS. To analyze the data was used Analysis of Variance-ANOVA, Pearson's Correlation and Linear Regression. A total of 283 individuals belonging to 15 species were analyzed. No species had an average concentration of HgTotal above that allowed by National Health Surveillance Agency-ANVISA and World Health Organization. However, in five species, some individuals had absolute individual concentrations that exceeded the limit tolerated for human consumption. A total of 283 individuals belonging to 15 species were analyzed. Auchenipterusnuchalis, an omnivorous / insectivorous food habit, was the species that presented the highest average concentration of HgTotal and also obtained the highest Bioconcentration Factor. The species Hemiodus unimaculatus, collected downstream of the reservoir showed a trend of higher concentration of HgTotal than collected upstream. There was no relationship between HgTotal levels in fish with HgTotal levels in water and sediment, nor with limnological variables. Catoprionmento, a detritus species, obtained the lowest mean concentration. Among the species studied, one presented bioaccumulation, Acestrorhynchuscf. Microlepis(piscivora).