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Poluição urbana e industrial em zonas costeiras - fitorremediação de metais em sedimentos de sapal
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Nos poluentes urbanos e industriais, os metais pesados são relevantes por serem persistentes, tóxicos e bioacumuláveis. Neste trabalho caracterizou-se as concentrações de Ni Cd, Pb, Zn e Cr nas águas pluviais da cidade de Faro descarregadas na Ria Formosa. Consideraram-se 3 estações, (A, B) próximas da cidade de Faro, e (C) adjacente a uma zona industrial em Olhão. Quantificaram se os metais nos sedimentos de sapal, avaliou-se o seu Potencial de risco ecológico (PRE) e a capacidade da Sarcocornia fruticosa para fitorremediar estes metais. As C.M.E das águas pluviais foram, por ordem decrescente Zn > Cr > Pb > Ni> Cd, sendo inferiores às obtidas noutras cidades. Nos sedimentos das estações A e B, os metais apresentaram concentrações por ordem decrescente Zn > Pb > Cr > Ni > Cd, sendo a estação A, a que apresentou maiores concentrações para todos os metais. Nos sedimentos da estação C as concentrações foram por ordem decrescente Zn > Cr > Pb > Ni > Cd. O PRE apresentou risco moderado na estação A e risco baixo para as estações B e C. As concentrações de Cd mostraram grande influência na toxicidade global dos sedimentos. Na estação A, a seguir ao Cd, o Pb foi o metal que mais contribuíu para a toxicidade do biota. Já na estação C, foi o Ni a segunda maior contribuição. A S. fruticosa remediou os metais estudados Fator de Enriquecimento (FE >1) nas 3 estações, acumulando-os sobretudo nas raízes, este comportamento demonstrou dependência com o nível de contaminação. Nas estações mais contaminadas a planta manteve os metais mais tóxicos (Cd, Ni e Pb) indisponíveis na rizosfera adsorvidos às raízes e no rizosedimento, não os translocando para os órgãos aéreos. A S. fruticosa evidenciou contribuir para a melhoria da resiliência desta lagoa costeira aos metais de origem antrópica, diminuindo a sua biodisponibilidade, e reduzindo os riscos ambientais e de saúde pública. Estes estudos devem ser aprofundados para melhorar o conhecimento da fitorremediação com esta planta.
Among urban and industrial pollutants, heavy metals are important as they are persistent, toxic and bioaccumulative. This work analyzed the concentrations of Ni, Cd, Pb, Zn and Cr from Faro city discharge, measured in two precipitation events in 2015 and their potential implications on Ria Formosa coastal lagoon. Three sample stations were selected, A and B nearby the urban settlement of Faro, and station C nearby an industrial zone, Olhão. The sediments were characterized and the metal concentrations were quantified. The (PER) was determined, as an indicator of toxicity for biota. Sarcocornia fruticosa's ability to metal remediation was evaluated, using the (EF), and metal translocation to aerial organs. The Mean Event Concentrations in stormwater were, in decreasing order Zn> Cr> Pb> Ni> Cd, being lower than those already obtained for other cities. In sediments of stations A and B, under urban influence, metals concentrations where in decreasing order Zn> Pb> Cr> Ni> Cd, station A presented higher concentrations than B, for all metals. In the sediments of station C, under industrial influence, concentrations were in decreasing order Zn> Cr> Pb> Ni> Cd. The PER on station A presented a moderate risk, and in stations C and B a low risk, whereas the risk was higher in C than in B. Cadmium concentrations when analyzed individually did not appear to be of concern, but had a major influence on overall sediment toxicity at the 3 stations. At station A, after Cd, Pb was the metal that most contributed to biota toxicity. In station C, Ni had the 2nd largest contribution. S. fruticosa remediated the studied metals (EF > 1) in the 3 stations, accumulating them mainly in the roots, this behavior indicated dependence on the metal contamination levels. In the most contaminated stations, this specie kept the most toxic metals (Cd, Ni and Pb) unavailable in the rhizosphere adsorbed to the roots and in the rhizosediment, not translocating them to the aerial organs. Therefore S. fruticosa showed to improve the resilience of this coastal lagoon to these metals, reducing their bioavailability, and decreasing environmental and public health risks. These studies should be extended to more metals and other stations in Ria Formosa, in order to improve the knowledge of the S. fruticosa’s phytoremediation capacity.
Among urban and industrial pollutants, heavy metals are important as they are persistent, toxic and bioaccumulative. This work analyzed the concentrations of Ni, Cd, Pb, Zn and Cr from Faro city discharge, measured in two precipitation events in 2015 and their potential implications on Ria Formosa coastal lagoon. Three sample stations were selected, A and B nearby the urban settlement of Faro, and station C nearby an industrial zone, Olhão. The sediments were characterized and the metal concentrations were quantified. The (PER) was determined, as an indicator of toxicity for biota. Sarcocornia fruticosa's ability to metal remediation was evaluated, using the (EF), and metal translocation to aerial organs. The Mean Event Concentrations in stormwater were, in decreasing order Zn> Cr> Pb> Ni> Cd, being lower than those already obtained for other cities. In sediments of stations A and B, under urban influence, metals concentrations where in decreasing order Zn> Pb> Cr> Ni> Cd, station A presented higher concentrations than B, for all metals. In the sediments of station C, under industrial influence, concentrations were in decreasing order Zn> Cr> Pb> Ni> Cd. The PER on station A presented a moderate risk, and in stations C and B a low risk, whereas the risk was higher in C than in B. Cadmium concentrations when analyzed individually did not appear to be of concern, but had a major influence on overall sediment toxicity at the 3 stations. At station A, after Cd, Pb was the metal that most contributed to biota toxicity. In station C, Ni had the 2nd largest contribution. S. fruticosa remediated the studied metals (EF > 1) in the 3 stations, accumulating them mainly in the roots, this behavior indicated dependence on the metal contamination levels. In the most contaminated stations, this specie kept the most toxic metals (Cd, Ni and Pb) unavailable in the rhizosphere adsorbed to the roots and in the rhizosediment, not translocating them to the aerial organs. Therefore S. fruticosa showed to improve the resilience of this coastal lagoon to these metals, reducing their bioavailability, and decreasing environmental and public health risks. These studies should be extended to more metals and other stations in Ria Formosa, in order to improve the knowledge of the S. fruticosa’s phytoremediation capacity.
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Keywords
Zonas costeiras Metais Toxicidade Fitorremediação S. fruticosa