Trophic state index phosphorus-based in the Paraguay-Diamantino basin in the Mato Grosso, Brazil

Abstract

The quality of the water can be altered naturally due to the contact with the rocky and edaphic substrate in the hydrological course, which can acquire characteristics of these substrates to a greater or lesser extent. However, urban demographic concentration, the technological advance of agricultural and industrial practices, among other anthropogenic actions, also influence water quality, generally in a negative and shocking way. Regardless of the origin of the quality change, it should be monitored for scientific knowledge and geo-environmental management. In this context, sampling was carried out in the nine water courses in the Paraguay-Diamantino basin, aiming to analyze the total phosphorus concentration and its effect on water eutrophication. For this, water samples were collected in four periods, according to rainfall, drought and transitional seasons, and determined from the Trophic State Index (EITP), as recommended by the National Water Quality Assessment Program (PNQA). There was a change in the EIT between the watercourses, between the collection periods and between points in the same watercourse, in this case the Paraguay River. The EIT varied between the weights 0.50, 1.00, 2.00 and 3.00. It was concluded that there is variation of water quality in relation to the EITP, pointing to diversity of phosphorus contamination, in relation to its concentration. The EITP fell within the highest quality classes and no concentration of phosphorus indicating acute eutrophication was found.