Avaliação dos possíveis impactos da atividade salineira através do monitoramento da qualidade da água e sedimento do estuário Tomás-Galinhos em Galinhos/RN

Abstract

The Rio Grande do Norte is the largest producer of salt, sodium chloride, the country and holder of 97% of all salt produced. In this context, Salina Diamante Branco - SDB in Galinhos, dismisses the whole process of brine in the study area, the river Thomas-Galinhos. Thus, it is essential to assess the possible impacts of this Salineira activity in the body of water adjacent. Thus, there was a physical-chemical monitoring of water quality and sediment to obtain an environmental assessment, including indicators of pollution, the Water Quality Index - IQW and Toxicidez Index. Most samples were collected from July 2014 to April 2016, three months, for a total of 32 collections for high and low tide. In these collections, there were two other heavy metals in water and sediment. All results were related to the standards required by resolutions 357 of 17 March 2005 and 344 of 25 March 2004, both the National Environmental Council - CONAMA. For non listed in the cited standards parameters, these were evaluated before its variability in the water body. The vast majority of results presented without great variations while maintaining the natural characteristics of the estuary, a fact that led the IQW all points as quality GOOD. In contrast, some levels of oxygen dissolved total phosphorus in water and sediment, and obtained chlorophyll, indicated a tendency to contamination by organic matter. However, these contaminants are from other activities in the surrounding communities. January and April, higher temperatures generally showed lower values of dissolved oxygen. Regarding metals in water, almost all were below the ICP-OES detection limit or below the limits required by CONAMA, indicating that these metals tend to be adduced by the dynamics of tidal or precipitated sediment, characterizing as IT = 1, absent contamination. Regarding metals in sediment was obtained also no toxicity. Brine disposal a priori influence the behavior of the salinity, however, do not alter the natural characteristics of the river, keeping a fixed range of salinity over the years. At low tide and periods of drought, we found a trend to a higher concentration of salts and nutrients. The location characteristic of each collection point also influenced the results. The values of calcium, magnesium and alkaline pH are characteristic of the body of water and studied underwent no significant changes.