Monitoring and identification of pollutant groups of the Lagoa Mirim

Abstract

Located on the Atlantic coast of South America, the Lagoa Mirim watershed occupies an area of 47,362 km2 of direct contribution and 55,110 km2 including the coastal strip. It has a high pollution index of agricultural origin because of the territorial extension of the areas used for this purpose. Another important factor that contributes to the pollution of this lagoon is the launching of untreated urban and industrial sewage into the São Gonçalo watercourse, where Lagoa Mirim interconnects with Lagoa dos Patos. This study aimed to use multivariate statistical methods, such as FA/PCA, to analyze the water quality of this water resource. Water samples were collected in 2014, 2015 and 2016 at eight monitoring points of Lagoa Mirim. Ten parameters of water quality were analyzed. In general, the variables showed a strong correlation with each other. There were four main components of quality for the water body studied with an accumulated explained variance of 80.24%. These components are mainly related to agricultural and urban pollution. The results attest to the relevance of using statistical methods for the monitoring of this lagoon. They also provide an idea of the processes that influence the water quality.