Water Quality Assessment of the Pardo River Basin, Brazil: A Multivariate Approach Using Limnological Parameters, Metal Concentrations and Indicator Bacteria

Located in the southeast of Brazil, the Pardo River Basin has a large population and an economy focused on agriculture, with a strong predominance of the sugarcane agro-industry. The purpose of the study was to assess the water quality of the Pardo River Basin under a multivariate approach using limnological parameters, metal concentrations, and indicator bacteria. Nine sampling campaigns were performed during both the dry and rainy seasons. Element concentrations were determined by inductively coupled plasma spectrometry (ICP-MS, Perkin Elmer Elan 6000). A battery of test to determine limnological parameters was performed (in situ). Total coliforms and Escherichia coli were detected and quantified using Defined Substrate Technology Colilert ® and multiple tube dilutions. Principal component analysis and hierarchical cluster analysis were used as multivariate exploratory analysis. In general, the results suggest the influence of rain, possible sewage discharges into the watercourse, and the input of organic matter in some sampling points in both seasons, besides the absence of riparian vegetation in much of the Pardo River. The likely influence of industrial activities that do not have great prominence in the region was supported by temporal/spatial assessment of Cr and V. The water quality monitoring of Pardo River is an important tool for environmental management, and its continuity is indicated to obtain a consistent series of systematic data and thereby support concretely the actions of planning and controlling the use of water from the Pardo River and soil around them.