Pesticide levels in Soil of a small Guarani settlement in Brazil

Abstract

BACKGROUND AND AIM: Pesticide uses skyrocket in Brazil in the last 20 years, our aim is to present an overview of the contamination at a small native settlement called “Tehoe Oco´y = Guaranis” (Native Americans) living near Itaipu HE Dam, Parana State. METHODS: In order to access the presence and the effects of some pesticides (glyphosate acephate, metamidophos and methomil) on the natural attenuation of the natural system, i.e. the potential for (bio) degradation and / or immobilization of contaminants we developed a biosensor based on the attenuation of flurescence of proteins.High sorption capacity in soil mineral fraction: low mobility in soils with high values of Cation Exchange Capacity; Competitive sorption with elements such as P, copper and zinc. RESULTS:High levels of pesticides were found in the soils, and the contamination coming from the soy and corn plantations in located very close to the guarani village seemns evident, Dynamics of sorption/desorption of glyphosate in soils presents a relevant variation considering the mineral fertility profile of Brazilian agricultural soils and their levels of P, Zn and Cu; The levels of P, Cu and Zn required for the displacement of glyphosate to the soil solution are 5 times lower than the concentrations found in Brazilian agricultural soils; Levels of glyphosate found in the soil and the P and Cu levels influenced the kinetics of the degradation enzymes in the samples; Sorption dynamics of glyphosate alters the kinetics enzyme by varying the desorbed concentration (present in the soil solution); CONCLUSIONS:Soil studies on the mobility of high toxicity metals potentially affects the fate of glyphosate.We need to review the agronomic recommendations of mineral fertilization and liming observing the management of pesticides. Importance of ecological (functional) studies on the impact of these contaminants on the maintenance and quality of environmental services, where natural attenuation is factor of their resilience; KEYWORDS: Herbicides, Fate, Soils, Native Americans