Physicochemical and mineralogical characterization of soil-saprolite cores from a field research site, Tennessee

Site characterization is an essential initial step in determining the feasibility of remedial alternatives at hazardous waste sites. Physicochemical and mineralogical characterization of U-contaminated soils in deeply weathered saprolite at Area 2 of the DOE Field Research Center (FRC) site, Oak Ridge, TN, was accomplished to examine the feasibility of bioremediation. Concentrations of U in soil-saprolite (up to 291 mg kg(-1) in oxalate-extractable U(o)) were closely related to low pH (ca. 4-5), high effective cation exchange capacity without Ca (64.7-83.2 cmol(c) kg(-1)), amorphous Mn content (up to 9910 mg kg(-1)), and the decreased presence of relative clay mineral contents in the bulk samples (i.e., illite 2.5-12 wt. %, average 32 wt. %). The pH of the fill material ranged from 7.0 to 10.5, whereas the pH of the saprolite ranged from 4.5 to 8. Uranium concentration was highest (about 300 mg kg(-1)) at around 6 m below land surface near the saprolite-fill interface. The pH of ground water at Area 2 tended to be between 6 and 7 with U concentrations of about 0.9 to 1.7 mg L(-1). These site specific characteristics of Area 2, which has lower U and nitrate contamination levels and more neutral ground water pH compared with FRC Areas 1 and 3 (ca. 5.5 and <4, respectively), indicate that with appropriate addition of electron donors and nutrients bioremediation of U by metal reducing microorganisms may be possible.     

Influence of chloride ions on the reduction of mercury species in the presence of dissolved organic matter

Environmental Geochemistry and Health - Mercuric species, Hg(II), interacts strongly with dissolved organic matter (DOM) through the oxidation, reduction, and complexation that affect the fate,...     

Quantification of ammonia and hydrogen sulfide emitted from pig buildings in Korea

The aim of this field study was to determine the concentrations and emissions of ammonia and hydrogen sulfide in different types of pig buildings in Korea to allow objective comparison between pig housing types in Korea and other countries. Concentrations of ammonia and hydrogen sulfide in the pig buildings averaged 7.5ppm and 286.5ppb and ranged from 0.8 to 21.4ppm and from 45.8 to 1235ppb, respectively. The mean emissions of ammonia and hydrogen sulfide per pig (normalized to 75kg liveweight) and area (m2) from pig buildings were 250.2 and 37.8mg/h/pig and 336.3 and 50.9mg/h/m2, respectively. Ammonia and hydrogen sulfide concentrations and emissions were higher in the pig buildings managed with deep-pit manure systems with slats and mechanical ventilation than in other housing types.     

Simultaneous leaching and carbon sequestration in constrained aqueous solutions

The behavior of metal ions’ leaching and precipitated mineral phases of metal-rich fly ash (FA) was examined in order to evaluate microbial impacts on carbon sequestration and metal immobilization. The leaching solutions consisted of aerobic deionized water (DW) and artificial eutrophic water (AEW) that was anaerobic, organic- and mineral-rich, and higher salinity as is typical of bottom water in eutrophic algae ponds. The Fe- and Ca-rich FAs were predominantly composed of quartz, mullite, portlandite, calcite, hannebachite, maghemite, and hematite. After 86 days, only Fe and Ca contents exhibited a decrease in leaching solutions while other major and trace elements showed increasing or steady trends in preference to the type of FA and leaching solution. Ca-rich FA showed strong carbon sequestration efficiency ranging up to 32.3 g CO₂/kg FA after 86 days, corresponding to almost 65% of biotic carbon sequestration potential under some conditions. Variations in the properties of FAs such as chemical compositions, mineral constituents as well as the type of leaching solution impacted CO₂ capture. Even though the relative amount of calcite increased sixfold in the AEW and the relative amount of mineral phase reached 37.3 wt% using Ca-rich FA for 86 days, chemical sequestration did not accomplish simultaneous precipitation and sequestration of several heavy metals.