Enhancing Bio-Available Phosphorous in Soil Through Sulfur Oxidation by Thiobacilli.

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.

Fate and Transport of Mercury in Environmental Media and Human Exposure / 예방의학회지

Mercury is emitted to the atmosphere from various natural and anthropogenic sources, and degrades with difficulty in the environment. Mercury exists as various species, mainly elemental (Hg0) and divalent (Hg2+) mercury depending on its oxidation states in air and water. Mercury emitted to the atmosphere can be deposited into aqueous environments by wet and dry depositions, and some can be re-emitted into the atmosphere. The deposited mercury species, mainly Hg2+, can react with various organic compounds in water and sediment by biotic reactions mediated by sulfur-reducing bacteria, and abiotic reactions mediated by sunlight photolysis, resulting in conversion into organic mercury such as methylmercury (MeHg). MeHg can be bioaccumulated through the food web in the ecosystem, finally exposing humans who consume fish. For a better understanding of how humans are exposed to mercury in the environment, this review paper summarizes the mechanisms of emission, fate and transport, speciation chemistry, bioaccumulation, levels of contamination in environmental media, and finally exposure assessment of humans.

Activity test for biological sulfate reduction.

Biofilm reactors with turbulent agitation are often the best choice for sulfate reduction using hydrogen as electron donor for treatment of metal sulfate wastewater. In this paper, a simple activity set-up with self aspiration of gas into liquid is described for determining the sulphidogenic activity of biofilms on polystyrene beads. Sulfate reducing bacteria attached to the beads of size 1-2 mm and 2 mm were found helpful for 0.058 g SO4(2-) reduction per g of dry beads per day and 0.33 g SO4(2-) reduction per g of dry beads respectively. Also it is observed that zinc has no impact on this activity at the concentration of 680 mg/L.