Groundwater Contamination in a Rural Municipality of Northeastern Brazil: Application of Geostatistics, Geoprocessing, and Geochemistry Techniques

Water is one of the most important natural resources that significantly affects the health and economy of a country. With global warming, drought has increased in rural areas, and based on this assumption, there is a growing need to monitor the water quality of rivers and aquifers in these areas. Therefore, this research aims to evaluate the quality of groundwater in the municipality of Candeias, Bahia, rural area of northeastern Brazil, correlating seasonality with the physicochemical parameters collected. A total of 135 samples were collected at six different points to assess possible sources of contamination. Geostatistics and geoprocessing techniques were used, such as principal component analysis (PCA) and inverse distance weighting (IDW) interpolation. The water quality indexes (WQI) of Brazil and Malaysia (ASEAN Group) together along with the water pollution index (WPI) were used to classify groundwater. The main results indicate high concentration of nitrate (3229.838 mg L-1) and chloride (2522.413 mg L-1) at point P5 and high concentration of sulfate (2293.244 mg L-1) at point P1, both in residential areas where groundwater is consumed by residents of the region. Seasonality influenced the concentrations of physicochemical parameters, as dry weather presented higher values than rainy weather. The WQI presented a moderate and poor classification in groundwater quality and as moderately polluted through the WPI. The geostatistical and geoprocessing tools used in this work proved to be efficient in evaluating the distribution of pollutants in a pioneering way in the northeast region of Brazil, since there is no work on groundwater contamination in this region. These data can serve to justify subsidies for the development of strategies, planning, and urban management with relevance to public health and the different uses of water by the population.