Evaluation of Concentrations of Heavy Metals in Water Used in Agricultural Irrigation

Abstract

The knowledge about toxic levels of toxic heavy metals in irrigation water is very scarce and quite varied. This work aimed to evaluate the concentrations of toxic heavy metals in the lake of the Experimental Farm UEMG, Passos-MG Unit. The toxic heavy metals evaluated were Cadmium (Cd), Chromium (Cr) and Lead (Pb). The lagoon was divided into ten strategic points for sampling, each point being sampled in triplicate. The pH of the water and the concentrations of toxic heavy metals present were evaluated. PH measurements were performed on the water in natura, being measured before and after filtration. Values ranging from 6.25 to 7.75 were found. For the determinations of Cd, Cr, and Pb, an Atomic Absorption Spectrophotometer was used. The samples were treated with acid digestion. The values of toxic heavy metals found were: Cadmium: 0.727 mg/L at 0.754 mg/L; Chromium: 0.177 mg/L at 0.256 mg/L and Lead: 0.023 mg/L at 0.081 mg/L. These values are above the limit established by CONAMA 357/2005. The dangers of contamination of water by toxic heavy metals are not restricted only to the direct consumption of this water, but also to the consequences in the food chain when we refer to bioaccumulative toxicants.