Atributos dos solos do estado do Pará e teores naturais de elementos potencialmente tóxicos em solos no entorno da rodovia Transamazônica, Amazônia Oriental.

Abstract

Abstract 1: Soil from Pará State show accentuated variability depending on both the diversity of parental material as bioclimatic conditions of the region. The variability in the factors and processes of soil formation affect biogeochemical processes, including absorption of nutrients and potentially toxic elements. The potentially toxic elements occurring in the environment at low concentrations. The potentially toxic elements study is oriented from the total content, however, the total content is not completely indicative of contamination, because only pari shows mobility in the soil profile and is available to plant absorption.The aim was evaluate the physical and chemical attnbutes of soil classes most representative from Pará State and determine the amounts of potentially toxic element available barium (Ba), cadmus (Cd), lead (Pb), cobalt (Co), copper (Cu), chrome (Cr), iron (Fe), manganese (Mn), aluminum (Al), and zinc (Zn) in the 0-0,2 m layer, fhrough extractors solutions, DTPA-TEA, Mehlich 1 e Mehlich 3,. Soil samples were collected in primary vegetation field with minimal anthropic intervention. The samples were air dried and passed through a 2 mm sieve. Were determined chemical analysis, pH in water, available P, exchangeable KT. Ca"+, Mg"'+ e Al+3, potential acidity and organic matter. With the results obtained in the sorption complex analysis were calculated the sum of exchangeable bases, the cation exchange capacity and base and Al saturation. Were determined SiOo, FesOs, AI2O3, MnO e TiO? oxides by sulfuric acid attack, oxalate and dithionite-citrate-bicarbonate and particle size analysis. Was performed Shapiro-Wilk normality test, Pearson correlation matrix, descriptive analysis, principal component analysis, cluster analysis, Kruskal-Wallis signifícance test (p< 0,05) and Kruskalmc test. The ratio Feo/Fed and Fed/Fet were low indicating predominance of crystalline forms in relation the amorphous and advanced degree weathering respectively, with low K+, P, Ca"+ and Mg2 amounts and high Al+J content in the exchange complex. The contents of silicon, aluminum and iron oxides extracted by sulfuric acid attack increased with depth and were different among soil classes with amounts higher in Inceptisols, Alfísols and Oxisols. The amount of Fe and Mg oxides were higher in Alfisols and Inceptisols, characterizing as rich soil in ferruginous minerais. The available amount of potentially toxic element in soils to DTPA-TEA in the order of Fe > Al >Mn> Ba > Cu > Zn > Co > Cd >Pb; Mehlich 1 Al > Fe >Mn> Ba > Cu > Zn > Co >Pb> Cd and Mehlich 3 were in the order of Al > Fe >Mn> Ba > Cu > Co> Zn >Pb> Cd. Significant correlations were established between metais and MO, pH, CTC, Fe and Mn oxides. The elements Cu, Mn, Fe and Zn show significant correlation among for all three methods, indicating similarity in the extracted form. Mehlich 3 was more effective to extract the metais Fe, Al, Mn and Pb than Mehlich 1 and DTPA-TEA and equally efficient for Cd, Mn, Zn and Cu. The contents of metais extracted by each method varied in the order M3, Ml and DTPA-TEA.

Abstract 2: The Amazon soils are naturally heterogeneous, due difference in parental material composition and pedogenic processes that act in the formation, resulting in the heterogeneity of attnbutes. Moreover, research about region soils are still incipients and based mainly in generalized surveys, which limits the planning sustainable natural resources. The aim was to characterize the chemical and physical attributes of soil classes most representative from Pará State. Were determined pH in water, avaüable P, exchangeable K+, Ca2+ , Mg2+ e Al+3. potential acidity and organic carbon. With the results obtained in the sorption complex analysis were calculated the sum of exchangeable bases, the cation exchange capacity and base and Al saturation. Were determined SIO2, Fe2O3, AI2O3, MnO e TIO2 oxides by sulfuric acid attack, oxalate and dithionite-citrate-bicarbonate and particle size analysis. Was performed principal component analysis, cluster analysis and descriptive analysis of the data. The contents K+, P, Ca2+ and Mg2+werelow and high Al+J content in the exchange complex, indicating dystrophic or alie character. Theratio Feo/Fed and Fed/Fet were low indicating presence of weathered soils. The among of silicon, aluminum and iron oxides extracted by sulfuric acid attack were higher in subsurface layer and differentiate between soil classes with bigher amounts in Inceptisols, Alfisols and Oxisols. The amount of Fe and Mg oxides were bigher in Alfisols and Inceptisols, characterizing as rich soil in oxidic minerais.

Abstract 3: The Flighway Transamazon is a frontier region where agricultural activities, mining and wood extraction, beyond big hydroelectric plants are the main economic activities responsible for leveraging development. These activities lead to environmental contamination by potentially toxic elements (PTEs). Environmental monitoring will only be possible by the determination of element contents in natural conditions. Several extraction methods have been proposed to determine the availability of metais in soils, however, there is no consensus about what is most appropriate extractor. In this study we determined the contents of PTEs in soils at the surrounding Highway "Transamazon after extraction with DTPA-TEA, Mehlich 1 and Mehlich 3. Soil samples were collected in areas with natural vegetation at the highway Transamazon ffom Para state. Were determined chemical and granulometric attributes, besides the content of Fe, Al, Mn and Ti by sulfuric acid attack. Si after attack alkaline; poorly crystalline oxides of Fe, Al and Mn, and "free" Fe. The Mehlich 3 solution extracted higher contents of Fe, Al and Pb, regarding Mehlich 1 and DTPA-TEA and similar contents for Cd, Mn, Zn and Cu. Correlations were found between the contents of EPTs and oxides of Fe and Mn beyond organic carbon and cation exchange capacity. Cu, Mn, Fe and Zn extracted by tbe three methods were positively correlated, indicating similarity in the forms extracted.