| Popis: |
The hydrographic basin of Sapucaia stream, located in the Metropolitan Region of Porto Alegre has its sources in the rural area. But, the middle and lower portions of this stream are located in urban areas characterized by a diversity of anthropogenic activities. Concerning the possibility that the stream may present specific contamination problems and in order to verify this, an evaluation of water and streambed sediments was performed from the geochemical-environmental perspective. Nutrients and major and trace elements were analyzed. The dynamic approach based on mass balance models, associated with the determination of natural and anthropogenic fluxes of the elements identified were used to study the geochemical behavior of streamwater. The streambed sediments were analyzed applying the contamination index that led to identifying the sources and distribution of possible contaminants. The results obtained for nutrient concentrates, major and trace elements in the water were compared to water quality standards as determined by current legislation. Concerning nutrients, the water of the Sapucaia are Class 3, indicating domestic effluent contamination. For the major elements, concentrates are higher than the medium Class 2 values and the trace elements are systematically lower than established by the CONAMA 20/86 class limit. The streambed sediments are clearly contaminated and classified as moderately polluted. Therefore, analyzing all points, it can be said that the methodology applied here is appropriate to achieve the desired objectives. The data obtained can be used to provide further information to improve environmental management of the Sapucaia hydrographic basin |
