Avaliação de metodologia de extração sequencial de Al, Cd, Co, Cr, Cu, Pb e Zn em solo do Rio Cará-Cará de Ponta Grossa, Paraná

Abstract

Sequential extraction is a widely used method for evaluating mobility, bioavailability, and metal toxicity. Thus, this work aimed to evaluate the extraction of aluminum, chromium, cobalt, copper, cadmium, lead, and zinc through four different sequential extraction methodologies using the soil from Ponta Grossa - PR, which, according to its physical-chemical characteristics, are classified as a dystrophic red latosol. The results obtained in this work demonstrated great relevance in the variables among the methodologies, such as the influence of volume, temperature, extraction time, and the extraction reagent. The evaluation of the several stages of sequential extraction aimed to estimate the behavior, aiming at the bioavailable fraction of the mentioned metallic species, was also possible since high pseudo-total values of chromium were observed in the analyzed soil, exceeding the permitted values by legislation, however, in a less mobile form connected to the mineralogical part of the soil was also observed for cadmium and zinc, pointing out that environmental legislation should not consider only the total concentration when evaluating the potentially toxic effects of metallic species. Nevertheless, a small fraction of cadmium and zinc seems to be in a labile form, indicating their source as anthropogenic activities. Changes in conditions such as pH and ionic strength can mobilize them into the interstitial solution and make them available.