BIOGEOCHEMISTRY AND CHARACTERIZATION OF CHEMICAL ELEMENT SOURCES FOR RIVER WATERS: AN ANALYSIS IN THE DESCOBRIMENTO NATIONAL PARK
watersheds, monitoring, conservation units.
The extreme south of Bahia is characterized by disorderly land use and occupation, which is responsible for negative environmental impacts on the region's watersheds. Historical changes in land use have been responsible for altering one of Brazil's main biomes, the Atlantic Forest, which is considered a biodiversity hotspot. The aim of the research was to assess the chemical composition of river water from the region's micro-watersheds, identifying the sources of chemical elements and discussing the influences of the buffer zone. Considering the proposed objective, water samples were collected at different sampling points in rivers located in the Descobrimento National Park, a UC in the far south of Bahia. Samples were taken from the Rio Cahy (RC), Rio Japara (J1, J2, J3), Rio do Sul (RS) and Rio Imbassuaba (RI). Physico-chemical parameters (pH, electrical conductivity, temperature, redox potential, DO) were assessed in the field. In the laboratory, the samples were filtered and chemical parameters such as alkalinity, MPS, chlorophyll-a, PO4-3 and SiO2, F-, Cl-, SO4-2, NO3-, NH4+, Na+, K+, Ca+2, Mg+2 were determined. The data was statistically treated by means of a factor analysis with extraction of the factors by principal components using Statistics software. The results indicate that river hydrochemistry is dominated by lithological influence in terms of ionic composition. The data was statistically treated by means of a factor analysis with extraction of the factors by principal components using Statistics software. The results indicate that river hydrochemistry is dominated by lithological influence in terms of ionic composition. Five factors were extracted from the factor analysis, which together explain 82.67% of the variation observed in the data. These variations can be explained by factors such as the influence of the Barreiras Geological Formation, which occurs in the region and the influence of the use of agricultural additives in the buffer zone (BZ) of the PND, as well as the process of liming the soil in this BZ. Finally, by characterizing the chemical composition of the fluvial waters at the different sampling points in the rivers of the PND, it was concluded that the fluvial waters receive marine influence, geological influence from the Barreiras Formation and anthropogenic influence due to the use of fertilizers from the PND buffer zone. The monitoring of fluvial biogeochemistry in the main rivers that cross the PND provided unprecedented data and information that will be used by the unit's management in most socio-environmental conflicts.