AVALIAÇÃO DA QUALIDADE DA ÁGUA E DO TEOR DE METAIS PESADOS EM PEIXES DO ESTUÁRIO DO RIO PERIZES (MA)

Abstract

Investigate the quality of water and fish in estuarine environments is undoubtedly extremely important, considering that a large part of the population depends almost exclusively on the goods offered by this ecosystem, especially fishery resources. In addition, the estuaries are on the list of natural environments that suffer most from anthropic interventions and consequently compromising the quality of water, fauna and flora. Therefore, the study sought to investigate the physico-chemical and microbiological parameters of water, as well as the levels of heavy metals in the muscle tissue of four species of fish (Genyatremus luteu – Peixe pedra, Macrodon ancylodon – Pescada Gó, Sciades herzbergii - Bagre and Guribu Mugil curema – Tainha Sajuba mullet) from the Perizes river estuary (MA). The samples were collected at four sampling points in the estuary mentioned between November 2017, January, March and May 2018. Fish specimens were captured by fishermen from the region, taking into account the sampling perimeter among the four collection points. The water analysis used the equipment. As for water analysis was used the equipment Kit-multiparameter HQ40D of Hach and disc of Secchi; Microbiological analysis by the multiple tube technique. In the analysis of the fish, the quantification of metals was verified by means of the atomic absorption spectrophotometry technique. The results of the environmental variables were satisfactory according to the maximum limits established by Resolution CONAMA nº 357/05, except for Turbidity that reached a maximum value, 449 UNT, in P3, in the month of Jan/18. There was presence of E. coli in most of the water samples. As for the quantification of the metals in the mentioned species, low concentrations of the metals (Al, Cu, Fe, Mn, Zn, Ni and Hg) were observed, unlike Cr and Pb. In general, the estuary has a certain degree of conservation, considering that the most environmental variables were in accordance with the CONAMA Resolution No. 357/05. Regarding thermotolerant coliforms, the results showed that the limits are lower than the resolution quoted, although it does not mean that the environment does not receive a load of contaminants. Therefore, the data presented in this study suggest the need for environmental monitoring, when considering that the surrounding families use the fish in their food diet and come in contact with the river water.