ABSTRACT
RESUMO No estado da Paraíba e no Brasil, a exploração do mineral vermiculita tem gerado grande volume de resíduos no entorno das mineradoras, que tem se tornado um passivo ambiental significativo, com potencial poluente ou contaminante. Dessa forma, neste trabalho, objetivou-se avaliar a influência de proporções do enxofre elementar (fonte p.a) adicionado ao resíduo da exploração de vermiculita sobre a liberação de nutrientes no solo. Para tanto, foi realizado experimento em delineamento inteiramente casualizado em fatorial 5×8, sendo 5 proporções de enxofre elementar (0, 50, 100, 150 e 200 g.kg−1) adicionadas ao resíduo de vermiculita e 8 períodos de incubação (0, 15, 30, 45, 60, 75, 90 e 105 dias) da mistura resíduo-enxofre, com 4 repetições, totalizando 160 parcelas experimentais. Durante 105 dias de incubação, a cada 15 dias, foram determinados, na mistura solo-resíduo-enxofre, os teores disponíveis de K, Na, Ca, Mg, P, SO4−2 e os valores de pH. O resíduo de mineração associado ao enxofre elementar proporcionou, na mistura, aumento significativo nos teores de sulfato, cálcio e fósforo disponíveis, redução do pH e dos teores de K. Os teores de Mg não foram influenciados pela adição do "aditivo"; já em relação aos teores de Na, houve aumento significativo. Conclui-se que a mistura rejeito-enxofre tem potencial para incrementar os teores de alguns nutrientes do solo. Contudo, seu uso pode ser limitado em solos com dificuldade de drenagem em razão do acúmulo excessivo de sódio trocável.
ABSTRACT In the state of Paraíba and in Brazil, the exploitation of the vermiculite mineral has generated a large volume of waste in the vicinity of the mining companies, which has become a significant environmental liability, with polluting or contaminating potential. Thus, in this work, the objective was to evaluate the influence of proportions of elemental sulfur (source p.a) added to the vermiculite exploration residue on the release of nutrients in the soil. For this purpose, an experiment was carried out in a completely randomized design in a 5 × 8 factorial, with five proportions of elemental sulfur (0, 50, 100, 150 and 200 g.kg−1) added to the vermiculite residue and eight incubation periods (0, 15, 30, 45, 60, 75, 90 and 105 days of incubation) of the residue-sulfur mixture, with four replications, totaling 160 experimental plots. During 105 days of incubation, every 15 days, the available contents of K, Na, Ca, Mg, P, SO4−2 and pH values were determined in the soil-residue-sulfur mixture. The mining residue associated with elemental sulfur, provided in the mixture, significant increase in the contents of sulfate, calcium and phosphorus available, reduction of the pH and of the contents of K. The contents of Mg were not influenced by the addition of the "additive", already in relation to Na levels, there was a significant increase. In conclusion, It is concluded that the sulfur-tailing mixture has the potential to increase the contents of some nutrients in the soil, however, its use may be limited in soils with drainage difficulties due to excessive accumulation of exchangeable sodium.
ABSTRACT
As a green and economic emerging technology, biological desulfurization is popular. However, biological desulfurization is inhibited by organosulfur in the treatment gases which cannot be ignored. This article summarizes relevant studies on the influence of organosulfur on biological desulfurization in recent years, including the types and physicochemical characteristics of organosulfur, the influence of organosulfur on the desulfurization process, the reaction mechanism of organosulfur, the interplay between organosulfur and some operating conditions, and species of microorganisms that are tolerant to organosulfur. Methods for mitigating the effect of organosulfur on the desulfurization process are discussed, to provide references for the stable and efficient operation of biological desulfurization.
ABSTRACT
Aims: The objectives were to evaluate the phosphate solubilization efficiency of different Thiobacilli strains and to find out the best combination of sulfur and Thiobacilli for enhancing bio-available P in soil. Study Design: An experimental study. Place and Duration of Study: Microbiology and Soil Fertility Labs, Department of Soil Science and Soil and Water Conservation, Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi, Pakistan and Microbiology and Soil Chemistry Labs, Auriga Research Center, Lahore, Pakistan, between May 2011 and November 2012. Methodology: Fifty Thiobacilli strains were isolated from ten different ecologies. Then an incubation study of soil was performed wherein the most efficient four Thiobacilli strains were inoculated in combination with three different levels of elemental sulfur to determine pH, water soluble sulfur, sequential P fractions and bio-available phosphorous contents in the incubated soil. Results: All the four Thiobacillus strains (IW16, SW2, IW1 and IW14) dropped pH of the incubated soil along with three doses of S° (50, 75 and 100 kg ha-1). However, Thiobacillus strains IW16 and SW2 reduced soil pH quite sharply from 7.90 to 7.12 (net reduction of 0.78 points) and 7.28 (net reduction of 0.62 points) respectively where inoculated with S° @ 100 kg ha-1. The best P solubilizer was Thiobacillus strain IW16 and the best dose of S° was @ 100 kg ha-1 and their combination enhanced maximum quantity of P (22.26 mg kg-1) in the soil by solubilizing already present insoluble calcium bounded P fractions like octacalcium phosphate (Ca8-P) and apatite (Ca10-P). Conclusion: The present study suggests the use of Thiobacilli along with elemental sulfur for the dissolution and enhancement of bio-available P in alkaline and calcareous soils.
Subject(s)
Oxidation-Reduction , Phosphorus , Soil/chemistry , Soil/microbiology , Soil Microbiology , Sulfates/metabolism , Sulfides/metabolism , Sulfur/metabolism , Sulfur-Reducing Bacteria/metabolism , Thiobacillus/chemistry , Thiobacillus/metabolism , Thiobacillus/physiologyABSTRACT
Reverse transcriptase-PCR experiments suggest that the two clusters of genes potentially involved in the oxidation of reduced sulfur compounds are organized as operons in strain of the acidophilic, chemolithoautotrophic bacterium Acidithiobacillus ferrooxidans ATCC 23270, the two clusters of genes including such the ORF of putative sulfate-thiosulfate-molybdate binding proteins, the ORF of putative thiosulfate: quinone oxidoreductase and the ORF of the rhodanese-like protein (P21). Bioinformatic analyses have predicted the possible promoters sequences and the possible +1 start site of transcription for the doxDA operons.
ABSTRACT
Metal sulfides are chemically attacked by Fe~ 3+ and H~+, resulting in the formation of elemental sulfur via polysulfides or thiosulfate pathway. Elemental sulfur may aggregate and even form a layer on the metal sulfide surface, which will inhibit leaching metals from the sulfides minerals. Elimination of inert elemental sulfur in a typical acidic environment can exclusively be by way of oxidation of acidophilic sulfur-oxidizing bacteria, such a way includes the attachment, transport and oxidation process of elemental sulfur by acidophilic sulfur-oxidizing bacteria. On the basis of analysis on the pertinent researches, the molecular mechanism of sulfur elimination by the acidophilic bacteria is far away from elucidated, and to attain that target, there are still much work to be done for elucidating the molecular mechanism on the attachment, transport and oxidation process of elemental sulfur by the acidophilic sulfur-oxidizing bacteria.