ABSTRACT
The aim of this study was to carry out a physicochemical analysis of water, sediment and riparian vegetation in a fish farm located near the Ribeirão da Mata basin in Minas Gerais State (Brazil). The water samples were collected weekly at four points: (1) source, (2) system entry, (3) discharge point, (4) and point release. The monitored physicochemical parameters in the water samples were: temperature (ºC), pH, dissolved oxygen, biochemical oxygen demand, total phosphorus, alkalinity, total dissolved solids, phosphate, nitrate, nitrite, sulfate, ammonia and phenol. Heavy metals (lead, cadmium, mercury and zinc) and pesticides (organochlorine, organophosphates, clorofosforados, carbamates, pyrethroids and anticoagulant rodenticides) were searched in the samples of water, sediment and riparian vegetation. Alkalinity and total solids presented the highest concentration, probably due to geological features of a carstic area. Phenol, at all points, and phosphate, at points 3 and 4, showed values above the limits allowed for class II freshwater, according to the CONAMA Resolution n. 357. The other parameters (ammonia, nitrate, nitrite and sulfate) in all sampling sites showed low values. It was not detected lead and mercury in the water samples; and zinc values were below 0.007 mg.L-1. However, the sediment samples showed lead values from 11.1566 to 37.0438 mg.L-1, with 12 of those samples above the quality reference value. In addition, it was detected mercury in all sediment samples, which ranged from 0.35 to 0.82 mg.L-1. It was not detected cadmium in samples of sediment neither plants. No pesticides were detected in the samples.
Keywords:
trace elements; pesticides; environment; environmental risk