Spatial and temporal distribution of thermotolerant coliform in Canal de Passagem (Vitória - ES) - related to physico-chemical parameters and tide

Abstract

The Canal de Passagem (CP), Vitória -ES, is an estuarine system undergoing a process of environmental degradation due to the discharge of in natura and semi-treated sewage. The surrounding local community's use of the estuarine resources conflicts with environmental quality and this offers risks to public health. The objective of this study was 1. to evaluate the distribution of fecal coliforms in the HCP (multiple tubes method), relating it to the distribution of sources of fecal pollution, the dynamics of the tides and physico-chemical parameters, and 2. evaluate the results in the light of the limits established by Brazilian legislation to ensure the health of the users of the water whatever the use to which it is put. Samples were taken spatially and temporally, to assess the tidal cycle of the spring tide in the winter, autumn and spring seasons, and also of the neap and spring tides at two sampling events in the summer. The sanitary parametersthermotolerant coliforms, physico-chemical, and tidal action, were considered. Meaningful correlations were found with the tidal regime. As conclusion, that the distribution of thermotolerant coliforms was related to the point sources of pollution, and the concentrations were different between spring and neap tides. This difference between tides is not taken into consideration by the Brazilian Bathing Water Legislation up to now. O Canal de Passagem, Vitória, ES, é um sistema estuarino em processo de degradação ambiental devido à descarga de esgoto in natura e semitratado. Os usos da comunidade do entorno dos recursos locais estuarinos são conflitantes com a qualidade ambiental, o que pode oferecer riscos para a saúde pública. Os objetivos do presente trabalho foram: 1. avaliar a distribuição de coliformes termotolerantes dentro do HCP (método dos tubos múltiplos), relacionando-a com a distribuição das fontes de poluição fecal, a dinâmica de marés e parâmetros físico-químicos, e 2. avaliar os resultados dentro das leis brasileiras de limites sanitários para os variados usos da água e balneabilidade. Amostras foram feitas espacialmente e temporalmente, visando cobrir o ciclo de marés de sizígia no inverno, outono e primavera, e também cobrindo uma quadratura e uma sizígia na amostragem no verão. Foram considerados os parâmetros sanitários -coliformes termotolerantes, físicos e químicos e a ação das marés. Correlações significativas foram encontradas com o regime das marés e distribuição de coliformes. A conclusão retirada do trabalho foi que a distribuição de coliformes termotolerantes esteve relacionada com as fontes pontuais de poluição, e as concentrações foram diferentes entre as marés de quadratura e sizígia. Variação entre tais marés não é observada até o momento pela Legislação Brasileira para as águas balneáveis. AbstrAct

Water quality assessment of the Demetrio stream: an affluent of the Gravataí River in the South of Brazil

“…In a previous study (Rio Grande do Sul, 2012), high levels of total coliforms, phosphorus, and chemical oxygen demand were observed, it could be associated with the lower dilution of domestic effluents from the Gravataí city. Alves et al (2015) studied the "Canal de Passagem" located in the Vitória city (Espírito Santo, Brazil) and stated that the places most affected with fecal pollution are closer to contamination sources. Oliveira et al (2012) also confirmed this trend along the Dilúvio stream in Viamão and Porto Alegre (Rio Grande do Sul, Brazil); however, in Lake Guaíba, a reduction in thermotolerant coliform concentration was noticed due to the interference resulting from the variation in water of the Lake.…”