Elementos-traço em solos de veredas do Triângulo Mineiro, região de Uberlândia, MG

Abstract

Cerrado wetlands (locally called as veredas) play important environmental roles, such as: carbon sink and reservoir; water storage and ground water maintenance; greenhouse gas emissions (N2O, CH4 and H2S); and ecological and social functions. Due to their position in the landscape, the wetlands are subjected to contamination by erosion sediments and runoff. This is may be critical after the significant transformation of native Cerrado for crop-livestock production during the past 40 years. This work was carried out aiming to evaluate the trace-elements concentration in soils from six veredas in the Brazilian Savanna Biome (Cerrado). Triplicate surface (0-20 cm) and subsurface (40-70 cm) samples were collected in the upper, middle and lowest position in the wetlands for physical and chemical characterization and to measure the concentration of As, Cd, Pb, Se, Ni, Zn, Cu, Mn and Fe (not trace element) by USEPA 3051A method. In each position in the wetlands, PVC tubes (1.5 m high and 15 cm diameter) were inserted into the soil (□ 1.0 m depth) to monitor monthly the ground water levei and to water sampling. The pH and electrical conductivity were measured in the water samples. The concentration of all trace-elements is below the threshold values established by Brazilian guidelines. Cationic trace-elements (Cd, Pb, Ni, Cu, Mn and Zn) were correlated to soil organic matter fractions. Anionic trace-elements were correlated to Fe and clay content. The cationic trace-elements concentration increased from the upper position to lowest position. This work evaluated six fragments of Cerrado wetlands around Uberlândia, MG, Brazil. So, the statement regarding the soil quality from veredas is not possible. The results from this work help to build-up the inventory of the trace-element concentration in soils from Cerrado wetlands.