Teores de metais disponíveis e atributos químicos em solos do Estado do Pará.

Abstract

The heavy metals studies request an appropriate approach due to impacts that these elements may bring to the environment, as to the society that depends on it. At Para State, studies quantifying the levels heavy metals that aim to obtain the values of available are yet incipient. In this way, this research is concerned in determine the available content of heavy metals in Para's soil in natural conditions, through three extractors; correlate those metals with some soil attributes and characterize the representative soils of Para State from the chemicals point of view. Soil samples of different depth were collected in areas of natural vegetation and/or with any or minimum anthropic intervention, what make a total of 264 samples. The samples were dried on air, unclodded and sieved on a mesh of 2 mm to obtain thin soil dried on air (TSDA). The chemical analysis was made and determined the available metals through the extractors: Mehlich-l, Mehlich-Ill and DTPA. The heavy metals determined on this research were: Ba, Cd, Cr, Pb, Cu, Mn, Ni and Zn. The heavy metals of the produced extracts were dosed by spectrometry of optical emission in plasma with induced coupling (Mehlich-Ill e DTPA) and through the atomic absorption (Mehlich-I). The results were processed using proceeds of descriptive statistics and Pearson correlations among metals, and soils attributes. The available content as the references values for heavy metals in Para State soils determined by the three extractors was inferior to the values of reference established by CETESB. Significant correlations were obtained between metals and the attributes: pH, organic matter and CTC. The pH presented negative correlation with Al in the three extractors. Correlations between the clay's fraction and the majority of determined metals were not found. The analyzed soil samples present a difference on the chemical characteristics according to different classes and depth. The determined values represent the natural reality of the following soil classes (Ferralsol, Acrisol Nitisol, Gleysol, Arenoso! and Plinthosol) and they may contribute to the Para State Soils Monitoring what aims a better environmental quality management.