Caracterização geoquímica do Estuário do Rio Una, BA, Brasil

Abstract

RESUMOCom uma vasta área estuarina, o sul da Bahia (Brasil) detém amplos recursos naturais. Os estuários agregam diversas dinâmicas ecológicas que contribuem significativamente no equilíbrio do ecossistema, trazendo à comunidade recursos sustentáveis valiosos. Atualmente esses recursos vêm sendo drasticamente explorados desordenadamente, e comunidades locais são as primeiras a serem prejudicadas. Entender e conhecer o comportamento geoquímico estuarino permite identificar estratégias ambientais, para uma exploração equilibrada desses ecossistemas. O presente trabalho teve o objetivo de caracterizar geoquimicamente o baixo curso do Rio Una através da análise dos parâmetros físico-químicos na água (temperatura, pH, oxigênio dissolvido, salinidade, Eh, conductividade, turbidez e sólidos totais dissolvidos) e metais (Ni, Cu, Cd, Pb e Cr) na água e no material particulado em suspensão. As amostras foram coletadas no período da seca em outubro de 2012 e na estação chuvosa em maio de 2013. Os maiores valores dos metais foram de Ni, Cu e Pb no material particulado em suspensão. O Cd foi o único elemento traço presente na fração dissolvida, o que indica uma possibilidade de contaminação da água em decorrência das atividades antrópicas circunvizinhas. Em geral, os valores de metais traço são considerados altos, quando comparados com os índices estabelecidos para sedimento.

Review on metal contamination in equatorial estuaries in the Brazilian Northeast

“…The particulate Zn in the EZBN estuaries was the only element with high concentrations in comparison to other Brazilian tropical estuaries, such as Rio Una (Bahia) and Paraíba do Sul (Rio de Janeiro) (Carvalho et al, 2002;Gonçalves and Carvalho, 2006;Jesus and Cruz, 2019). The Jaguaribe estuary showed particulate Cu and Pb concentrations two and five times lower, respectively, than Rio Una, while particulate Al and Fe were three times lower than concentrations observed in the Paraíba do Sul.…”

“…Comparing the range of dissolved trace metals to other Brazilian tropical estuaries under anthropogenic pressure, such as Tapacurá River (Pernambuco), Rio Una (Bahia), Sepetiba Bay (Rio de Janeiro), and Lagoa dos Patos (Rio Grande do Sul), and the Brazilian legislation (CONAMA n o 357, 2005 we can recognize high values Frontiers in Earth Science frontiersin.org for most metals found in estuaries of the EZBN, except dissolved Cd and Mn, which were 7.1 and 1.6 times lower than CONAMA values for brackish water, respectively (CONAMA n o 357, 2005;Molisani et al, 2007;Aprile and Bouvy, 2010;Barbosa et al, 2012;Jesus and Cruz, 2019). Tapacurá River and Rio Una identified enrichment of dissolved Cu, Zn, and Cd as a result of surrounding anthropic activities such as domestic sewage and agriculture runoff (Aprile and Bouvy, 2010;Jesus and Cruz, 2019). These elements are probably available to aquatic organisms and cause harm due to high metal toxicity.…”

“…The Bacanga estuary was indicated as moderately to heavily contaminated (Class 3), while the Parnaíba River Delta and Curimataú estuary were found heavily contaminated for this element (Class 4). Pb is a toxic metal to aquatic biota and humans (Jesus and Cruz, 2019;Kütter et al, 2021), but the main source of Pb for the region is mainly from natural contribution, urban runoff, inadequate disposal of solid waste, and Pb present in aerosols resulting from the burning of fossil fuels. Pb can be correlated with suspended particulate material, which may favor the co-precipitation of Pb with Fe-Mn oxyhydroxides and PbCO 3 in an environment with pH > 6 (Nascimento, 2013;Paula Filho et al, 2014;Azevedo, 2019;Santos et al, 2019), explaining the large spatial distribution of Pb in these estuarine sediments.…”

Reviews in Geochemistry: 2022

“…Comparing the range of dissolved trace metals to other Brazilian tropical estuaries under anthropogenic pressure, such as Tapacurá River (Pernambuco), Rio Una (Bahia), Sepetiba Bay (Rio de Janeiro Frontiers in Earth Science frontiersin.org for most metals found in estuaries of the EZBN, except dissolved Cd and Mn, which were 7.1 and 1.6 times lower than CONAMA values for brackish water, respectively (CONAMA n o 357, 2005;Molisani et al, 2007;Aprile and Bouvy, 2010;Barbosa et al, 2012;Jesus and Cruz, 2019). Tapacurá River and Rio Una identified enrichment of dissolved Cu, Zn, and Cd as a result of surrounding anthropic activities such as domestic sewage and agriculture runoff (Aprile and Bouvy, 2010;Jesus and Cruz, 2019). These elements are probably available to aquatic organisms and cause harm due to high metal toxicity.…”

“…The Bacanga estuary was indicated as moderately to heavily contaminated (Class 3), while the Parnaíba River Delta and Curimataú estuary were found heavily contaminated for this element (Class 4). Pb is a toxic metal to aquatic biota and humans (Jesus and Cruz, 2019;Kütter et al, 2021),…”