Water quality monitoring of the Pirapó River watershed, Paraná, Brazil.

E C Bortoletto,H A Silva,C M Bonifácio,C R G Tavares

doi:10.1590/1519-6984.00313suppl

E C Bortoletto, H A Silva + Show 2 more

Open Access

https://doi.org/10.1590/1519-6984.00313suppl

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Abstract

This study aimed to evaluate the water quality of the Pirapó River watershed in Paraná, Brazil, and identify the critical pollution sites throughout the drainage basin. The water quality was monitored during the period from January 2011 to December 2012. Nine points distributed throughout the main channel of the Pirapó River were sampled for a total of 17 samplings. The water quality was evaluated based on the determination of 14 physical, chemical and microbiological parameters. Analysis of the variables monitored in the Pirapó River watershed using factor analysis/principal components analysis (FA/PCA) indicated the formation of three distinct groups of parameters: water temperature (Twater), dissolved oxygen (DO) and a group composed of total suspended solids (TSS), turbidity and nitrite (NO2⁻). The parameters Twater and DO exhibited a relationship with the seasonality, and the TSS, turbidity, and NO2⁻ levels were correlated with surface runoff caused by rainfall events. Principal component analysis (PCA) of the sampling points enabled the selection of the 10 most important variables from among the 14 evaluated parameters. The results showed that the nitrate (NO3⁻), NO2⁻, TSS, turbidity and total phosphorous (TP) levels were related to the soil type, and the parameters DO, electrical conductivity (EC), ammoniacal nitrogen (N-NH3) and thermotolerant coliforms (TC) were related to organic matter pollution, with the P5 sampling site being the most critical site. The ordination diagram of the sampling points as a function of the PCA indicated a reduction from 9 to 5 sampling points, indicating the potential for decreasing the costs associated with monitoring.

Highlights

The gradual decline of surface water quality is directly related to the discharge of municipal sewage and industrial effluents into water bodies, the inadequate disposal of solid wastes and surface runoff from agricultural areas
The formation of 3 distinct groups is observed: three distinct groups of parameters: water temperature (Twater), dissolved oxygen (DO) and a group composed of total suspended solids (TSS), turbidity and nitrite
The application of factor analysis/principal components analysis (FA/principal component analysis (PCA)) to the monitored variables of the Pirapó River watershed indicated the formation of three distinct groups: Twater, DO and a group composed of TSS, turbidity and nitrite

Summary

Introduction

The gradual decline of surface water quality is directly related to the discharge of municipal sewage and industrial effluents into water bodies, the inadequate disposal of solid wastes and surface runoff from agricultural areas. The quality of surface waters is directly related to the type of land use, landscape modification, the removal of native vegetation for monocropping, the indiscriminant use of pesticides and fertilizers and a lack of human and animal waste treatment (Almeida et al, 2001; Luz, 2009). Considering the growing influence of anthropogenic factors on water quality, namely, the type of use and occupation of the physical environment and socio-economic activities, it becomes necessary to distinguish the natural characteristics of water from those attributed to human activities (Rebouças et al, 1999).

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