The role of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans in arsenic bioleaching from soil

Bioleaching of As from the soil in an abandoned Ag–Au mine was carried out using Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. A. ferrooxidans is an iron oxidizer and A. thiooxidans is a sulfur oxidizer. These two microbes are acidophilic and chemoautotrophic microbes. Soil samples were collected from the Myoungbong and Songcheon mines. The main contaminant of the soil was As, with an average concentration of 4,624 mg/kg at Myoungbong and 5,590 mg/kg at Songcheon. A. ferrooxidans and A. thiooxidans generated lower pH conditions during their metabolism process. The bioleaching of As from soil has a higher removal efficiency than chemical leaching. A. ferrooxidans could remove 70 % of the As from the Myoungbong and Songcheon soils; however, A. thiooxidans extracted only 40 % of the As from the Myoungbong soil. This study shows that bioleaching is an effective process for As removal from soil.     

Geochemical and Geophysical Monitoring of Salinewater Intrusion in Korean Paddy Fields

The saline water intruded zone in paddy fields near the seashore can be diagnosed accurately by joint exploration with geophysical and geochemical methods. Using the electromagnetic (EM) sounding technique, the weakly consolidated zone which introduces saline water into such an area of near seashore paddy fields in Korea was detected from the variation of electrical conductivity distribution following field irrigation. Vertical electrical sounding (VES) with Schlumberger array and chemical analysis of top soils, and groundwater in the study area verified the intruded zone near the surface. The VES results showed that the intrusion of seawater occurred in the form of a channel down to 30 m below sea level. Geochemical analysis of the top soil samples for the six major elements found in seawater indicated that the region showing high concentrations is concordant with the weakly consolidated zone near the surface. The degree of contamination in the study area was investigated by comparing the soil data with those from a nearby old reclamation field. If remediation work is not done for this intrusion zone, the sodicity degree in the paddy soil is expected to increase compared with the reference site data.     

Variation of dust layer height in the northern Taklimakan Desert in April 2002

LIDAR observations were conducted in the northern Taklimakan Desert to investigate the vertical distribution of dust in April 2002. During the observation period, a dust outbreak occurred on 13 April, remaining over the desert for several days. Despite only slight variations being observed in dust layer height before the dust event, marked diurnal variation in dust layer height was observed after the dust event. In this study, we conducted two numerical simulations to investigate differences in the variation exhibited by the dust layer heights before and after the dust event, and assessed the influence of meteorological conditions on this variation. The simulated results show that the clearly diurnal variation in dust layer height is strongly influenced by local circulation which is affected by the characteristic topography and synoptic conditions of the Tarim Basin.     

Effects of climatic factors on the prevalence of influenza virus infection in Cheonan,Korea

Environmental Science and Pollution Research - Big data can be used to correlate diseases and climatic factors. The prevalence of influenza (flu) virus, accounting for a large proportion of...     

Comparison of hematite/Fe(II) systems with cement/Fe(II) systems in reductively dechlorinating trichloroethylene

Reactive reductants of cement/Fe(II) systems in dechlorinating chlorinated hydrocarbons are unknown. This study initially evaluated reactivities of potential reactive agents of cement/Fe(II) systems such as hematite (alpha-Fe(2)O(3)), goethite (alpha-FeOOH), lepidocrocite (gamma-FeOOH), akaganeite (beta-FeOOH), ettringite (Ca(6)Al(2)(SO(4))(3)(OH)(12)), Friedel's salt (Ca(4)Al(2)Cl(2)(OH)(12)), and hydrocalumite (Ca(2)Al(OH)(6)(OH).3H(2)O) in reductively dechlorinating trichloroethylene (TCE) in the presence of Fe(II). It was found that a hematite/Fe(II) system shows TCE degradation characteristics similar to those of cement/Fe(II) systems in terms of degradation kinetics, Fe(II) dose dependence, and final products distribution. It was therefore suspected that Fe(III)-containing phases of cement hydrates in cement/Fe(II) systems behaved similarly to the hematite. CaO, which was initially introduced as a pH buffer, was observed to participate in or catalyze the formation of reactive reductants in the hematite/Fe(II) system, because its addition enhanced the reactivities of hematite/Fe(II) systems. From the SEM (scanning electron microscope) and XRD (X-ray diffraction) analyses that were carried out on the solids from hematite/Fe(II) suspensions, it was discovered that a sulfate green rust with a hexagonal-plate structure was probably a reactive reductant for TCE. However, SEM analyses conducted on a cement/Fe(II) system showed that hexagonal-plate crystals, which were presumed to be sulfate green rusts, were much less abundant in the cement/Fe(II) than in the hematite/Fe(II) systems. It was not possible to identify any crystalline minerals in the cement/Fe(II) system by using XRD analysis, probably because of the complexity of the cement hydrates. These observations suggest that major reactive reductants of cement/Fe(II) systems may differ from those of hematite/Fe(II) systems.     

Mercury and cadmium in common cormorants (Phalacrocorax carbo)

Mercury (Hg) and cadmium (Cd) in common cormorants (Phalacrocorax carbo) collected in Lake Biwa, Japan and Tokyo, Japan, were investigated to elucidate the biological behaviors of these elements, and to assess exposure to these pollutants of wild, fish-eating birds. Hg and Cd concentrations were highest in the liver and kidneys, respectively. The lowest levels of both elements were observed in chicks. Hg concentrations in all tissues except brain increased significantly with growth from chicks to juveniles (p<0.05, U-test). Cd concentrations in the kidneys and liver also increased significantly during growth from juvenile to adult (p<0.005, U-test). When comparing hepatic Hg and Cd in adult birds between 10 samples from Lake Biwa and nine samples from Tokyo, the Cd concentrations in the Lake Biwa samples (1.4+/-0.37 microg/g dry wt) (mean+/-SD) were significantly higher than those from Tokyo (0.32+/-0.16 microg/g dry wt) (p<0.005, U-test), while no statistically significant difference was found in the Hg concentrations. Possible causes of these differences were discussed in relation to their prey.     

Food web structure of a restored macroalgal bed in the eastern Korean peninsula determined by C and N stable isotope analyses

Loss of macroalgae habitats has been widespread on rocky marine coastlines of the eastern Korean peninsula, and efforts for restoration and creation of macroalgal beds have increasingly been made to mitigate these habitat losses. Deploying artificial reefs of concrete pyramids with kelps attached has been commonly used and applied in this study. As a part of an effort to evaluate structural and functional recovery of created and restored habitat, the macroalgal community and food web structure were studied about a year after the establishment of the artificial macroalgal bed, making comparisons with nearby natural counterparts and barren ground communities. Dominant species, total abundance, and community structure of macroalgal assemblage at the restored macroalgal bed recovered to the neighboring natural bed levels during the study period. The main primary producers (phytoplankton and macroalgae) were isotopically well separated. δ¹³C and δ¹⁵N values of consumers were very similar between restored and natural beds but varied greatly among functional feeding groups. The range of consumer δ¹³C was as wide as that of primary producers, indicating the trophic importance of both producers. There was a stepwise trophic enrichment in δ¹⁵N with increasing trophic level. A comparison of isotope signatures between primary producers and consumers showed that, while suspension feeders are highly dependent on pelagic sources, invertebrates of other feeding guilds and fishes mainly use macroalgae-derived organic matter as their ultimate nutritional sources in both macroalgal beds, emphasizing the high equivalency of trophic structure between both beds. Isotopic signatures of a few mollusks and sea urchins showed that they use different dietary items in macroalgal-barren grounds compared with macroalgal beds, probably reflecting their feeding plasticity according to the low macroalgal biomass. However, isotopic signatures of most of the consumers at the barren ground were consistent with those at the macroalgal beds, supporting the important trophic role of drifting algae. Our results revealed the recoveries of the macroalgal community and trophic structure at the restored habitat. Further studies on colonization of early settlers and the following succession progress are needed to better understand the process and recovery rate in the developing benthic community.     

Trichloroethylene degradation by photocatalysis in annular flow and annulus fluidized bed photoreactors

The effects of trichloroethylene (TCE) gas flow rate, relative humidity, TiO(2) film thickness, and UV light intensity on photodegradation of TCE have been determined in an annular flow type photoreactor. Phosgene and dichloroacetyl chloride formation could be controlled as a function of TCE gas flow rate and photodegradation of TCE decreased with increasing relative humidity. The optimum thickness of TiO(2) film was found to be approximately 5 mum and the photocatalytic reaction rate of TCE increased with square root of UV light intensity. In addition, the effects of the initial TCE concentration, phase holdup ratio of gas and solid phases (epsilon(g)/epsilon(s)), CuO loading on the photodegradation of TCE have been determined in an annulus fluidized bed photoreactor. The TCE photodegradation decreased with increasing the initial TCE concentration. The optimum conditions of the phase holdup ratio (epsilon(g)/epsilon(s)) and CuO wt.% for the maximum photodegradation of TCE was found to be 2.1 and 1.1 wt.%, respectively. Therefore, an annulus fluidized bed photoreactor is an effective tool for TCE degradation over TiO(2)/silica gel with efficient utilization of photon energy.     

Threshold dependence of mortality effects for fine and coarse particles in Phoenix, Arizona

Daily data for fine (< 2.5 microns) and coarse (2.5-10 microns) particles are available for 1995-1997 from the U.S. Environmental Protection Agency (EPA) research monitor in Phoenix, AZ. Mortality effects on the 65 and over population were studied for both the city of Phoenix and for a region of about 50 mi around Phoenix. Coarse particles in Phoenix are believed to be natural in origin and spatially homogeneous, whereas fine particles are primarily vehicular in origin and concentrated in the city itself. For this reason, it is natural to focus on city mortality data when considering fine particles, and on region mortality data when considering coarse particles, and most of the results reported here correspond to those assignments. After allowing for seasonality and long-term trend through a nonlinear (B-spline) trend curve, and also for meteorological effects based on temperature and specific humidity, a regression of mortality was performed on PM using several different measures for PM. Based on a linear PM effect, we found a statistically significant coefficient for coarse particles, but not for fine particles, contrary to what is widely believed about the effects of coarse and fine particles. An analysis of nonlinear pollution-mortality relationships, however, suggests that the true picture is more complicated than that. For coarse particles, the evidence for any nonlinear or threshold-based effect is slight. For fine particles, we found evidence of a threshold, most likely with values in the range of 20-25 micrograms/m3. We also found some evidence of interactions of the PM effects with season and year. The main effect here is an apparent seasonal interaction in the coarse PM effect. An attempt was made to explain this in terms of seasonal variation in the chemical composition of PM, but this led to another counterintuitive result: the PM effect is highest in spring and summer, when the anthropogenic concentration of coarse PM is lowest as determined by a principal components analysis. There was no evidence of confounding between the fine and coarse PM effects. Although these results are based on one city and should be considered tentative until replicated in other studies, they suggest that the prevailing focus on fine rather than coarse particles may be an oversimplification. The study also shows that consideration of nonlinear effects can lead to real changes of interpretation and raises the possibility of seasonal effects associated with the chemical composition of PM.