Seasonal evaluation of surface water quality at the Tamanduá stream watershed (Aparecida de Goiânia, Goiás, Brazil) using the Water Quality Index

Abstract

Freshwater is an essential natural resource for humanity, however, its quality has been compromised as a result of natural and anthropogenic interference. The objective of the present study was to determine the Bascarán Water Quality Index (WQI B ) for the Tamanduá stream in the municipality of Aparecida de Goiânia, Goiás, Brazil, and relate it to the limits established by CONAMA resolutions n 357 [1] and n 274 [2], for Class 2 freshwater bodies. The study was carried out at three sampling points proximate to urban parks, with samples collected in both the dry and the rainy seasons with the measurement of flow. The physical, chemical and biological parameters were analyzed as recommended in Standard Methods [3]. Parametric descriptive statistics were used for data analysis. The WQI B results classified the water as acceptable (24%), normal (48%), improper (20%) and unpleasant (8%), with turbidity, DO and total coliforms responsible for decreased WQI B in the rainy season. The parameters pH, apparent color and DO do not conform with CONAMA resolution n 357 [1] while water resources for bathing were classified as excellent according to CONAMA resolution n 274 [2].