ABSTRACT: The parent geological materials and formation factors influence the chemical, physical, and mineralogical properties and composition of the soil. Therefore, the aims of this study were to determine the chemical and some physical and mineralogical properties of the soil useful for agricultural practice; to determine the natural contents of the semitotal metals in soils of the state of Rio Grande do Sul (Brazil); and to suggest use of the quality reference values (QRVs) in accordance with Resolution 420/2009 of the National Commission for the Environment (Conama). To determine some soil properties useful for agricultural, 254 surface soil samples from areas without known human influence (native grasslands or forests) were analyzed according to the methodology used by the soil testing laboratories of the state of Rio Grande do Sul. In addition, the semitotal heavy metal (Cd, Co, Cr, Cu, Ni, Pb, V, and Zn) contents of the soil were determined by the Usepa 3050B method and Hg was determined through an adaptation of the Usepa 7471 method. The results were studied in five soil groups from the state of Rio Grande do Sul according to soil parent materials: (1) basalt (volcanic rocks) of the Plateau region, (2) crystalline rocks (granite, schists, etc.) of the Southern Shield, (3) pelitic rocks (siltstones, mudstones, etc.) of the Peripheral Depression, (4) sandstones (sedimentary) of the Central Plains, and (5) sediments (unconsolidated) of the Coastal Plains. The properties for agricultural use of these soils were compared using the criteria adopted by the current fertilizer recommendations for the state. Multivariate analysis was used to study metals contents. Average values of available P contents were low in all soil groups; however, average values were high in several soil groups for available K. Averages of total acidity and cation exchange capacity were higher in Group 1 soils. The average values of extractable Zn, Cu, and S were high in all soils. Averages of Fe oxides were higher in the soils formed over basalt than in the other soils. Average metal (Cd, Co, Cr, Cu, Ni, Pb, V, and Zn) contents were higher in Group 1 soils than in the other soil groups (2 to 5). For Hg, however, average values were similar for all soil groups. The Spearman correlation coefficients were positive and highest among the metals (except for Cd and Hg) and the clay, Fed, and extractable Cu soil properties. Another high positive correlation coefficient was found between semitotal Cu and Zn contents and organic carbon. The QRVs for Cd, Co, Cr, Cu, Hg, Ni, Pb, V, and Zn, determined according to Conama Resolution 420/2009, followed the same trend as the average metals contents.

O antraceno e os demais hidrocarbonetos aromáticos policíclicos (HAPs) podem ser removidos do solo pela biorremediação, cuja eficiência é limitada se as condições físicas e químicas não forem favoráveis à sobrevivência e à atividade dos microrganismos degradadores. O objetivo do presente estudo foi avaliar a influência do pH, da umidade e da disponibilidade de nitrogênio, de fósforo, de ferro e de enxofre na biorremediação de um solo contaminado com antraceno. Para tanto, amostras de um solo arenoso foram contaminadas em laboratório com 500mg kg-1 de antraceno e a mineralização desse poluente foi quantificada por respirometria. As maiores mineralizações ocorreram nos tratamentos com as maiores umidades e os pH avaliados. A adição de 100kg ha-1 ou mais de nitrogênio no solo e a redução da relação C HAP-N para valores inferiores a 120:17 diminuíram a mineralização do antraceno. O aumento da disponibilidade do fósforo, do ferro e do enxofre e a presença de amplas relações C HAP:P no solo não influenciaram a mineralização do antraceno. A correção do pH e o adequado fornecimento de água possibilitaram a biorremediação desse solo em curto período de tempo.

The anthracene, as well as the others polycyclic aromatic hydrocarbons (PAH), can be removed from the soil by bioremediation, whose efficiency is limited under unfavorable physical and chemical conditions to the survival and activity of the microbial degraders. The objective of this study was to evaluate the influence of pH, water content, and nitrogen, phosphorus, iron and sulfur concentrations in the bioremediation of a soil contaminated with anthracene. Samples of a sandy soil were contaminated in laboratory with anthracene (500mg kg-1) and the mineralization was evaluated by respirometry. The highest anthracene mineralization was verified in the soil with the highest water content and pH value studied. The addition of 100kg ha-1 nitrogen in the soil and the consequent reduction of CPAH-N ratio to values lesser than 120:17 reduced anthracene mineralization. The increase of phosphorus iron and sulfur availability and wide CPAH-P (120:1 to 120:22) ratios in the soil did not influence anthracene mineralization. The pH correction and appropriate water supply made possible the bioremediation of the soil polluted with anthracene in a short period of time.

Os resíduos gerados na exploração de carvão mineral e no processamento de peles são produtos potencialmente poluentes em várias regiões do Brasil, principalmente nos Estados do Rio Grande do Sul e de Santa Catarina. O presente trabalho foi conduzido a campo com o objetivo de avaliar o efeito da aplicação e da reaplicação de resíduos carbonífero e de curtume ao Cr sobre as plantas de milho e de soja cultivadas em um Argissolo Vermelho distrófico típico, na Estação Experimental da UFRGS, localizada no município de Eldorado do Sul (RS). A primeira aplicação dos resíduos foi feita no ano agrícola de 1996/97 e a reaplicação no ano agrícola de 1999/2000. As doses de resíduos de curtume variaram conforme o pH do solo e o poder de neutralização do resíduo, tendo sido adicionadas quantidades cumulativas de Cr entre 671 a 1,342 kg ha-1. A quantidade acumulada de resíduo carbonífero foi de 164 t ha-1. Foram avaliados os efeitos das aplicações dos resíduos sobre o rendimento e a absorção de N, P, K, Ca, Mg, Cu, Zn e Cr pelas plantas. A adição de lodo de curtume propiciou rendimentos de milho e de soja semelhantes aos obtidos com a adição de N mineral e de corretivo da acidez. Não foram observadas alterações significativas na absorção de Cr pelas plantas. O efeito acidificante do solo apresentado pelo resíduo carbonífero pode ser controlado por aplicações adequadas de lodo de curtume alcalino.

Tannery residues and coal mine waste are heavily polluting sources in Brazil, mainly in the Southern States of Rio Grande do Sul and Santa Catarina. In order to study the effects of residues of chrome leather tanning (sludge and leather shavings) and coal waste on soybean and maize crops, a field experiment is in progress since 1996, at the Federal University of Rio Grande do Sul Experimental Station, county of Eldorado do Sul, Brazil. The residues were applied twice (growing seasons 1996/97 and 1999/00). The amounts of tannery residues were applied according to their neutralizing value, at rates of up to 86.8 t ha-1, supplying from 671 to 1.342 kg ha-1 Cr(III); coal waste was applied at a total rate of 164 t ha-1. Crop yield and dry matter production were evaluated, as well as the nutrients (N, P, K, Ca, Mg, Cu and Zn) and Cr contents. Crop yields with tannery sludge application were similar to those obtained with N and lime supplied with mineral amendments. Plant Cr absorption did not increase significantly with the residue application. Tannery sludge can be used also to neutralize the high acidity developed in the soil by coal mine waste.