Geological and anthropic influence on the water quality of a northern Pantanal Stream, Brazil

Abstract

Studies about the quality of water resources are an important tool for the management of aquatic environments. Thus, we sought to analyze the water quality of the Jacobina stream in the rural region of Cáceres/MT, Northern Pantanal, in relation to lithology and the use and coverage of land around the basin. For this purpose, the basin was compartmentalized in high, medium and low courses and the sampling comprised the dry and flood period, which are characteristic of the Pantanal. For the survey of the geological units of the basin, a thematic map was elaborated using satellite images Landsat TM 5 and TM 8. The identification of the use and coverage of the surrounding land was raised through on-site visits with the application of questionnaires on the rural properties that cover the stream. In each compartment, a water collection point was adopted. 25 limnological variables were analyzed and the Water Quality Index (WQI) was applied. The results showed that, in general, the water quality of the Jacobina stream is 'Excellent' according to the values obtained by calculating the WQI and by presenting the variables that were within the limits of the current legislation of CONAMA 357/05 and 430 / 11 and MS 2914/11. The stream waters are possibly influenced by the rocky material, mostly limestone, demonstrated by the parameters of Ca²⁺, Mg²⁺, alkalinity and pH. Thus, this study made it possible to relate the activities developed around the Jacobina stream, as well as the natural characteristics of the environment, such as water quality.