Qualidade das águas superficiais e subterrâneas das microbacias do Cumaru e São João, nordeste paraense.

Abstract

The present study aimed to characterize the quality of surface and underground waters of the watersheds of the Cumaru and São João streams, through the most important physical-chemical and biological parameters, relating the results to the use and occupation of the soil in the region. For water monitoring, 6 similar land use systems were selected for the two microbasins, being fallow vegetation, Agroforestry System (SAF), planting area prepared for slash and burn, planting area prepared for cut and crunch, Pasture and Vegetation Ripary. In these, three surface water collection stations were established in the Cumaru stream micro-basin and four stations in the São João stream micro-basin, as well as thirty (30) observation wells (piezometers) were drilled. The variables analyzed were: Precipitation, temperature, flow, pH, EC, turbidity, DO, Na+, NH4+, K+, Mg2+, Ca2+, Cl-, NO3-, PO43-, SO42-, DOC, DIC, TN, Thermotolerant coliforms and OBD. Collections were carried out monthly. Subsequently, 97 socio-environmental questionnaires were applied to communities living in the two microbasins. The main results obtained revealed that the waters of the two studied watersheds are characterized as acid and have low dissolution of inorganic ions, especially Cl- and Na+ ions, which presented the highest concentrations observed throughout the study, characterizing them predominantly as Sodium Chlorinated and Chlorinated Mixed. The springs were less impacted in relation to the other stretches in the two microbasins, in the order NasSJ > NasC. The practice of preparing the soil based on the burning of the area, is notably, one of the main sources of changes in water quality, followed by the removal of fragments of secondary vegetation for implantation of pastures and use of water for other purposes (recreation and dumping of domestic sewage). For the surface waters of the ICU microbasin, the AF/ACP technique generated three components (84.22%), being Nutritional (DOC, DIC, Na+, NH4+, Ca2+, Cl- and PO43-), biological (thermotolerant coliforms) and physicochemical (pH, CE and DO). For the surface waters of the ISJ microbasin, the technique generated two components (85.08%), being Nutritional (Na+, NH4+, Ca2+, Cl- and PO43-) and biological (thermotolerant coliforms). The perception of the interviewed communities regarding the environmental quality of the area is revealed to be vulnerable, representing potential impacts on the health of residents, and on the environment in which they live.