Spatial and temporal diagnosis of the physicochemical and microbiological conditions of Tanquinho’s Stream, Ribeirão Preto, SP, Brazil

Abstract

The aim of the study was to evaluate the physico-chemical and microbiological conditions of Tanquinho's Stream, located in a highly urbanized and industrialized area in Ribeirão Preto, SP, Brazil, taking into account spatial and temporal variations. The following limnological parameters were evaluated: pH, temperature, turbidity, conductivity and dissolved oxygen (DO), with measurements in situ. Metal levels in sediment and surface water were analyzed by Atomic Absorption Spectrometry. The Multiple Tubes technique with chromogenic substrate was used to determine Total Coliforms and Escherichia coli. The parameters of DO, E. coli and the concentration of Cu and Mn in the water are not in accordance with national legislation. The metals found in higher concentrations in the sediment were Mn, Cr and Zn. The microbiological evaluation showed sewage discharges into the stream and the metal concentrations indicate possible industrial effluents, which may cause serious public health problems. The spatial diagnosis indicated the sampling sites with the worst microbiological conditions and high concentrations of metals, while the temporal influence was observed in the pH, Mn and Cr in surface water, and Mn, Cr and Pb in the sediments. The results indicate that Tanquinho's Stream is an impacted water body. It is recommended that further studies be conducted to clarify the source of pollutants and to assess the degree of public awareness, and that measures be adopted to ensure the recovery and protection of this water body.