SORÇÃO-DESSORÇÃO E MINERALIZAÇÃO DE PESTICIDAS CLASSIFICADOS COMO PRIORITÁRIOS EM SOLOS DO MUNIXÍPIO DE RIO VERDE, GOIÁS

Abstract

The use of pesticides in agricultural areas is necessary in order to improve production, but its misuse can cause negative impacts on the terrestrial and aquatic environment, and human health. In general, compounds that so used, sorbed, leaching, persistent and toxic should receive priority attention, because their dynamic will be controlled by the retention, transformation and transport processes, which dictate their availability, persistence and the possibilities of transference to other environments. The objective of this study was to generate basic information about the potential environmental contamination from pesticides commercialized in Rio Verde – GO, applying GUS and GOSS index. Two of the pesticides classified as priority were tested on their dynamic in soil (sorption-desorption and mineralization) in a clayey and sandy soil, at three different depths. There were commercialized 117 active ingredients, and the most used ones were: glyphosate, atrazine, paraquat, imazethapyr and 2,4-D, belonging to herbicide class; acephate, methomyl, chlorpyrifos, malathion and imidacloprid, belonging to the insecticide class; and carbendazim, thiophanate-methyl, tebuconazole, azoxystrobin andpyraclostrobin, belonging to fungicide class. Among the active ingredients identified as priorities, atrazine and chlorpyrifos were selected for the laboratory studies. Kf coefficients ranged from 3.69 to 10.09 mL g-1 for atrazine and 21.56 to 41.77 mL g-1 for chlorpyrifos. Both pesticides had a low mineralization rate, < of 21% for 62 days of the study, and chlorpyrifos mineralized faster, with a maximum rate of 20.33%. On the other hand, only 4.71% of the initially applied atrazine concentration mineralized. It can be concluded that chlorpyrifos is more sorbed and mineralized than atrazine, because it has greater affinity with soil clay and organic matter content, which directly influence the dynamics of these pesticides in the soil