Estudo hidrogeoquímico aplicado à geologia médica de poços para o abastecimento humano ao longo da BR 290 em Caçapava do Sul, Rio Grande do Sul

Abstract

The groundwater is that which in the subsoil saturation zone, limited by a layer impermeable in the base, and water table in the top. Deep wells are that colecting this water. Shallow wells reach the subsurface aeration zone, where not all pores are filled with water. Both situations may harbor elements detrimental to human health, whether due to anthropogenic or geological interaction. The present work deals with the hydrochemistry of seven water samples, being one of them collected after passing through the water box, two of shallow wells, and the resting of groundwater, and all aimed at human consumption with the aim of ensuring water that is not harmful to consumers' health. Those who do not collect groundwater served as a counterpoint to the discussions The área of study is limited to northeast region of Caçapava do Sul – RS, in length along the BR 290, approximately 50 km². It fits into two types of terrain: the sedimentary rocks of Camaquã Basin; and the metassedimentary rocks of São Gabriel Terrain. Both is located in Sul-Rio-Grandense shield (ESRG). Comparing field work, environmental analysis and laboratory analyzes, together with the bibliographic research, it was verified that only samples 2 and 5 can be classified within the standard of potability defined by the Ministério da Saúde. The other samples present coliform bacteria, which may indicate fecal contamination. Even being within the maximum values allowed for hardness and alkalinity, whose parameters are directly related to the Ca and Mg contente, four samples (1, 1.1, 2, 3 e 6) presented values close to the maximum allowed. In contrast, the other three samples (3, 4 e 5) presented low values. If they exceed the values proposed by the concierge the first group of samples can generate salty flavor and precipitate in the form of carbonates, generating incrustations in the pipes; and the second group may favor one of the many factors that contribute to cardiovascular disease.