Avaliação da qualidade da água de corpos hídricos no Extremo Sul da Bahia

Abstract

This study aimed to assess in an integrated and complex way the water quality of the Jardim and Mutari rivers, located in the extreme south of Bahia through the physical-chemical assessment of water, land use and occupation and variation in the structure of the planktonic community. The collections were carried out in the months of April and July 2019 (rainy period) and May and October 2019, (dry period), in 8 sampling points chosen according to the access and ordered in the nascent - mouth direction. The physical-chemical and biological parameters measured in the water were temperature, hydrogen 23 potential (pH), salinity, dissolved oxygen, biochemical oxygen demand (BOD), nitrite, nitrate, ammonia, total nitrogen (NT), total phosphorus (PT), total dissolved solids, total and thermotolerant coliforms and planktonic community, the data being compared with reference values established by CONAMA Resolution No. 357/2005. The parameters pH, OD, DBO, PT and NT showed values that were in disagreement with those allowed by the legislation, mainly in points closer to the mouth that is urbanized. In relation to planktonic organisms, an inversely proportional pattern was observed between the dominance of cladocera and copepoda (cyclopoid). In urbanized environments there is a higher prevalence of cladocera and in the protected region of copepoda. The multivariate statistical analysis Manova, allowed to identify differences between the rivers Jardim and Mutari and between urbanized and protected environments, when they were compared to the data of physical-chemical parameters of the water and the zooplankton community. In this way, we proved the importance of assessing environmental quality from multivariate sets, in addition, the supervised classification allowed the visualization of anthropic activities and the negative influence of urbanization and agricultural activities that occur throughout the basin