Uso e ocupação em zona ripária e sua implicação na qualidade do solo e da água na Lagoa do Boqueirão, Touros-RN

Abstract

The riparian zones are areas of water interference, that is, regions of conservation and preservation of the watershed in which it is inserted. They ensure the balanced operation of all systems (fauna, flora and water resources) and reduce the entry of pollutants into water bodies. The use and occupation of these spaces can reduce soil quality, for example, increase vulnerability to erosion, due to the surface runoff of existing nutrients in the soil to the water body. Thus, the objective of this work was to understand the influence of land use and occupation in a riparian zone, on the physical and chemical attributes of the soil and on water quality, in order to identify indicators of the processes of environmental degradation resulting from soil occupation riparian zone of Lagoa of Boqueirao in the municipality of Touros/RN. For data collection, soil samples were collected in different classes of use and then analyzes of the attributes were carried out: granulometry, soil density, particle density, total porosity, pH, electrical conductivity, organic matter and available phosphorus were performed. In relation to Lagoa, monitoring data from IGARN (Rio Grande do Norte State Water Management Institute) were used through the analysis of the attributes: pH, dissolved oxygen (DO), turbidity, total phosphorus, total solid, ammonia nitrogen, Escherichia Coli, chlorophyll-a, conductivity, total dissolved solids, total suspended solids, total alkalinity and phytoplankton - quantitative. The evaluation of the obtained data was made from the Pearson Correlation and PCA - Principal Component Analysis. The predominant class in the riparian zone of Lagoa do Boqueirão is native vegetation (68,92%) followed by exposed soil (24,90%). As a result of this change in the landscape towards anthropic uses, there was a reduction in soil quality due to soil compaction and erosion, in addition to the excessive supply of nutrients. In view of this, the ability to compromise the water quality of the water body can be increased. Soil compaction in areas with exposed soils is related to cattle trampling, while losses of finer particles in areas of agriculture and exposed soil are associated with erosive processes. In other words, the physical and chemical attributes selected were efficient as indicators of soil and water quality, in addition to distinguishing anthropic and natural environments.