Volume 26, Number 1, 2002

Knowing the susceptibility of a soil to compaction is important to adjust soil management, tillage practices, and traffic to cause minimal detrimental effects on soil properties. The objective of this study was to determine the preconsolidation pressure (σ’p) and the compression index (Cc) at two depths of two soils under no-tillage and conventional tillage, including a wide variation of the state of compaction. Undisturbed soil samples were collected with rings (5.4cm wide and 2.0cm high), at 0 to 2 and […]

Soil water content is one of the determining factors in controlling compaction caused by animal trampling or machinery traffic.The objective of this study was to evaluate the effect of water content (pore water saturation) on preconsolidation pressure (σ’p) and compression index (Cc) values, for two soils with contrasting textures, at two depths, cultivated under no tillage and conventional tillage.Undisturbed soil samples (5.35cm of diameter for 2cm of height) were collected in the surface layer (0 to 2cm) and in the […]

The objectives of this study were to evaluate the parameters from isotherms of Freundlich and Langmüir that best reflect the adsorption of heavy metals in weathered soils, and to identify the relationship between the selected parameters and the chemical, physical and mineralogical attributes of twelve representative soil classes from Brazil.The soils were collected by EMBRAPA-CNPS during various surveys in the Southern, Southeastern and Northern areas of Brazil.The correlation coefficient among dependent variables, obtained through the isotherms of adsorption (parameters of […]

To investigate the mineralogical variations with depth, 11samples were collected down to 14m, in an exposed sediment packet of the Barreiras Group in Aracruz, Espírito Santo, Brazil.The sand, silt and clay fractions were studied by X-ray diffraction, differential thermal analysis, thermogravimetry and electron microscopy.The total contents of Fe in the clay and silt fractions and Ti and Zr in the silt fraction were determined by ICP after fluoridric acid extraction.Clay and silt fractions were submitted to selective and sequential mineral […]

Barreiras Group sediments (Coastal Tablelands) are very poor in primary mineral containing nutrients.To study the distribution of K, Mg and other metals in minerals of clay, silt and sand fractions, 11 samples were collected at depths of 0.7; 1.4; 2.1; 2.8; 3.5; 4.2; 4.9; 5.6; 7.7; 10.5 and 14m, in an exposed sedimentary sequence of the Barreiras Group, in Aracruz (19o49’13″S 40o16’24″W), Espírito Santo, Brazil.The total contents of K, Mg, Ca, Al, Fe, Ti, Mn, Cu, Zn, Ni, Pb, Cr, […]

Detailed chemical and crystal properties of the kaolinite (Ka) and iron oxides in the Barreiras Group soils and sediments (Coastal Tablelands) are little known. Eleven samples were collected (0,7; 1,4; 2,1; 2,8; 3,5; 4,2; 4,9; 5,6; 7,7; 10,5 and 14m) in an exposed sediment sequence in Aracruz, Espírio Santo State, Brazil, in order to study the characteristics of these minerals with depth. Clay and silt fractions were studied by X-ray diffraction (XRD), differential thermal analysis and electron microscopy. Total contents […]

Acid drainage, resulting from sulfide oxidation, is an environmental problem which may impair soil and water sources quality. Such impact may occur in several environments, but it is commonly related to coal mining. This work was carried out to study the kinetics of pyrite oxidation in coal mining spoil from Candiota (RS) Brazil, under different conditions of atmospheric O2 access and pH. The study aimed to evaluate the possibility of adjusting carbonate dissolution rate to the sulfide oxidation rate in […]

The geochemical behavior in soil alteration profiles in Lavras (MG), Brazil, was evaluated during the process of soil formation leading to the formation of argillic horizons, in parent material ranging from acid, intermediate to mafic geochemical composition.Along each profile, from the consolidated bedrock to the solum, geochemical analyses of major elements-main oxides were performed, calculating the gains and losses through a mass chemical balance.The results showed a moderate loss of SiO2, bases leaching, and a slight relative enrichment of Al, […]

The geochemical behavior of trace elements (TE) and rare earth elements (REE) was evaluated in the region of Lavras (MG), during the pedogenetic evolution in soil profiles with argillic horizons differentiated by acid, intermediate and basic compositions of the parent material.Chemical analyses of TE and REE were performed along the profiles and gains and losses were evaluated through mass chemical balance.The study allowed to group the TE into two classes: (a)moderate to high mobility: loss from the consolidated rocks to […]

This work was carried out to study methods of sulfide analysis to obtain a fast, accurate and reproducible procedure to evaluate acid drainage in samples of rocks and sediments.The samples were submitted to oxidative digestions with H2O2 and nitric-hydrochloric acid solutions (3:1, v/v).The S in the extracts was determined by gravimetry, atomic absorption spectrophotometry (AAS) for remaining Ba, turbidimetry and colorimetry.The Fe and Pb contents in the extracts were determined by AAS.Acidity was also determined by titration with NaOH in […]