Influência do despejo de esgoto doméstico nas características limnológicas do rio Camandocaia, bacia hidrográfica do rio Piracicaba, Estado de São Paulo

Abstract

The objective of the present study was to investigate the influence of domestic sewage on the water along the Camandocaia River. The limnological variables analyzed were: pH, turbidity, color, manganese, iron, dissolved oxygen, nitrogen and total phosphorus. The data are discussed in terms of average values, and the Principal Component Analysis was employed. At no point were the oxygen saturation values below 70%, with the exception of point 9 (38.8%). The lowest nitrogen values were detected in points 1 to 3 (0.18 to 0.21 mg L -1) and the highest in points 9 and 10 (1.29 and 1.79 mg L -1); the highest phosphorus value was detected in point 9 (345.5 μg L -1). All variables correlate positively to the principal component 1, with the exception of oxygen saturation. The sum of the two principal components explains 86.6% of total variation found. The water of the river was little impacted by domestic sewage until Amparo. The highest levels of pollution were detected at the end of that city, and the trend was partial self-depuration until confluence with the Jaguary River. Nevertheless, the most polluted point of the river, when compared to other polluted rivers, presented lower pollution levels.