Assessment of Pollutants in Soils and Groundwater from the Coastal Plain of Paraíba do Sul River Delta, RJ, Brazil

Abstract

In developing countries, the quality of the available freshwater is deteriorating mainly due to pollution. Underground water bodies are important resources, taking into account that they are usually more isolated and also protected from anthropogenic influence. Within this context, the present study aimed to assess trace metals, nitrate and organic contaminants in groundwater and soils from 10 bore wells located at the coastal plain of the Paraíba do Sul river delta. Groundwater of the study area revealed elevated concentrations of arsenic, iron, manganese and barium, surpassing the limits established by Brazilian legislation as well as the limits established by other regulatory agencies. As, Fe and Ba reached concentrations as high as 242.70, 31 919 and 4.041 µg.l-1 in groundwater. Despite the elevated values, results suggested a reducing environment and the contaminants appear to have a natural geogenic origin, which is corroborated by past studies in the same area. Soils of the aquifer presented low levels of trace metals, corroborating the hypothesis of geogenic contamination in groundwater. No significant differences among the bore wells were observed regarding trace metals in soils, and concentrations found in the present study were much lower than the ones found in impacted aquifers around the world. No PCB's were detected in groundwater or soils. Nitrate concentrations in groundwater were within the limits recommended by Brazilian legislation.