Determination of oxidative metabolism in Collembolan Proisotoma minuta (Tullberg)

An oxidative metabolism of Collembolan Proisotoma minuta was determined with a model compound of aldrin and dieldrin in this paper. The seven-day LD(50) values for aldrin, dieldrin, and piperonyl butoxide in salt solution were 0.496, 0.367, and 8.346 mg L(-1), respectively. When P. minuta were exposed to aldrin, dieldrin was the sole metabolite. The conversion of aldrin to dieldrin was known to be catalyzed by P450 monooxygenases system. It has been shown that the synergist piperonyl butoxide inhibited the metabolism of aldrin in P. minuta.     

Anthropogenic mercury emission inventory with emission factors and total emission in Korea

Mercury emissions concentrations, emission factors, and the total national emission from major anthropogenic sources in Korea for the year 2007 were estimated. Uncontrolled and controlled mercury emission factors and the total emission from each source types are presented. The annual national mercury emission from major anthropogenic sources for the year 2007, on average was 12.8 ton which ranged from 6.5 to 20.2 ton. Averaged emissions of elemental, oxidized, and particulate mercury were estimated at 8.25 ton, 3.69 ton, and 0.87 ton, respectively. Due to the removal of a major portion of particulate and oxidized mercury species, elemental mercury was dominant in stack emission. About 54.8% of mercury emission was contributed by industrial sources, 45.0% by stationary combustion sources and 0.02% by mobile sources. Thermal power plants, oil refineries, cement kilns and incinerators (municipal, industrial, medical, sewage sludge) were the major mercury emitters, contributing about 26%, 25%, 21% and 20%, respectively to the total mercury emission. Other sources (crematory, pulp and paper manufacturing, nonferrous metals manufacturing, glass manufacturing) contributed about 8% of the total emission. Priority should be given in controlling mercury emissions from coal-fired power plants, oil refineries, cement kilns and waste incinerators. More measurements including natural and re-emission sources are to be carried out in the future in order to have a clear scenario of mercury emission from the country and to apply effective control measures.     

Catalytic reduction of sulfur dioxide with carbon monoxide over tin dioxide for direct sulfur recovery process

SO(2) reduction by CO over SnO(2) catalyst was studied in this work. The parameters were the reaction temperature, space velocity (GHSV) and [CO]/[SO(2)] molar ratio. The optimal temperature, GHSV and [CO]/[SO(2)] molar ratio were 550 degrees C, 8000 h(-1) and 2.0, respectively. Under these conditions, the SO(2) conversion and sulfur selectivity were about 78% and 68%, respectively. The following reaction pathway involving two mechanisms was proposed in SO(2) reduction by CO over SnO(2) catalyst: in the first step involving Redox mechanism, the elemental sulfur was produced by the mobility of the lattice oxygen between SO(2) and SnO(2) surface. In the second step, COS was formed by the side reaction between elemental sulfur and CO or metal sulfide and CO. In the third step involving COS intermediate mechanism, the abundant elemental sulfur was produced by the SO(2) reduction by COS which was produced in the second step and was more effective reducing agent than CO.     

Zoo animal manure as an overlooked reservoir of antibiotic resistance genes and multidrug-resistant bacteria

Environmental Science and Pollution Research - Animal fecal samples collected in the summer and winter from 11 herbivorous animals, including sable antelope (SA), long-tailed goral (LTG), and...     

Toluene vapor capture by activated carbon particles in a dual gas-solid cyclone system

Capturing of odorous compounds such as toluene vapor by a particulate-activated carbon adsorbent was investigated in a gas-solid cyclone, which is one type of mobile beds. The test cyclone was early modified with the post cyclone (PoC) and a spiral flow guide to the vortex finder. The proposed process may contribute to the reduction of gases and dust from industrial exhausts, especially when dealing with a low concentration of odorous elements and a large volume of dust flow. In this device, the toluene capturing efficiency at a 400 ppm concentration rose up to 77.4% when using activated carbon (AC) particles with a median size of 27.03 μm. A maximum 96% of AC particles could be collected for reuse depending on the size and flow rate. The AC regenerated via thermal treatment showed an adsorption potential up to 66.7% throughout repeated tests.

Implications: VOCs and particles have been of interest both in industrial field and public indoor spaces. In this study, a post cyclone (PoC) that utilizes a residual vortex from the mother cyclone was modified by inserting a flow guide and was applied to capture toluene vapor. The device of modified post-cyclone system can be used effectively in simultaneous treatment of gas-solid flow.     

Examination of Critical Factors Related to Summer Chlorophyll a Concentration in the Sueo Dam Reservoir, Republic of Korea

This study examined critical factors related to the short-term variation of algae growth in reservoirs during the summer. To this end, statistical tests were carried out at a small dam reservoir to determine how chemical factors (e.g., nutrient concentrations) and physical factors (e.g., theoretical and relative residence times, temperature) influenced the chlorophyll a (Chl-a) concentration. Statistical tests revealed that, although phosphorus (P) concentration was significant for Chl-a, residence time had much stronger relationship to Chl-a concentration than chemical factors. In addition, the study verified that relative residence time (RRT) best explained the relation of water status to algae growth. RRT was found to be useful in identifying water status related to the summer algae bloom. Finally, this study raised the possibility of inhibiting summer algae growth by operating dam reservoirs moderately. These findings need to be seriously considered when reservoir operators establish effective strategies for water quality management in summer.     

Volatile Organic Compounds in Ambient Air at Four Residential Locations in Seoul, Korea

To investigate the environmental behavior of volatile organic compounds (VOCs) in urban areas, their concentrations were measured at four urban monitoring sites (namely, N, S, E, and W) in Seoul, Korea (February to December 2009). A total of 27 compounds were quantified that consist of four chemical groups: aromatic (AR), halogenated aromatic, halogenated paraffin, and halogenated olefin. Results were evaluated by focusing on these four functional groups just mentioned and their summation term as total VOC (TVOC) along with several individual species (mainly AR species, that is, benzene, toluene, ethylbenzene, and xylene). The highest concentration of chemical groups was found from AR (71.1±42.1?ppbC), while that for individual species confirmed the dominance of toluene (7.48±3.88?ppb). The analysis of spatial distribution indicated that high TVOC levels were recorded at sites N and W, while it was not so significant such as S and E in terms of TVOC budget. Seasonal variation of these VOCs was characterized by the peak values in December to reflect the combined effects of pronounced source activities and meteorological conditions. Analysis of spatial variations in VOC levels between the four urban sites indicated that their distributions are tightly affected by local source processes in each area.     

Nitrate and ammonium ions removal from groundwater by a hybrid system of zero-valent iron combined with adsorbents

Nitrate (NO(3)(-)) is a commonly found contaminant in groundwater and surface water. It has created a major water quality problem worldwide. The laboratory batch experiments were conducted to investigate the feasibility of HCl-treated zero-valent iron (Fe(0)) combined with different adsorbents as hybrid systems for simultaneous removal of nitrate (NO(3)(-)) and ammonium (NH(4)(+)) ions from aqueous solution. The maximum NO(3)(-) removal in combined Fe(0)-granular activated carbon (GAC), Fe(0)-filtralite and Fe(0)-sepiolite systems was 86, 96 and 99%, respectively, at 45 °C for 24 h reaction time. The NO(3)(-) removal rate increased with the increase in initial NO(3)(-) concentration. The NO(3)(-) removal efficiency by hybrid systems was in the order of sepiolite > filtralite > GAC. The NH(4)(+) produced during the denitrification process by Fe(0) was successfully removed by the adsorbents, with the removal efficiency in the order of GAC > sepiolite > filtralite. Results of the present study suggest that the use of a hybrid system could be a promising technology for achieving simultaneous removal of NO(3)(-) and NH(4)(+) ions from aqueous solution.     

The role and distribution of total suspended solids in the macrotidal coastal waters of Korea

Spatial and temporal distribution patterns of total suspended solids (TSS) in the shallow and macrotidal regions of the Korean peninsula indicated there were significant changes in TSS concentrations. These were seasonally influenced by the wind, river input and tidal cycle. There were high TSS values at estuarine and river mouth stations and during low tide due to the re-suspension of bottom sediment by strong wind action during winter months, in addition the land input through rivers and strong tidal current during ebbing. Monthly mean values of TSS significantly correlated with wind speed and nitrate concentration (p < 0.01). This indicated that the resuspension of surface sediment was a more important source of TSS than the river input, and that nitrate was introduced into the water column during the resuspension process. TSS were seven times higher at low tide than in high tide. Light penetration was significantly inhibited by TSS; as >98% of incident light was absorbed within 2 m and zero photosynthetically active radiation (PAR) under 2 m in the estuarine stations during winter. Removal of heavy metals and nutrients by TSS in the water column was evident. Over 80% of the initial concentration of nutrients was removed within 10 min under various concentrations of TSS and also TSS contained significantly higher concentration of heavy metals than surface sediment. The concentration levels of nutrients and chemical oxygen demand in the west coast were comparable with the East and South Sea, even the major rivers in the Korean peninsula flow into the West Sea with major pollutant loadings into the coastal areas. High concentration of TSS is likely to contribute to the removal process of these pollutants, resulting in relatively lower levels of nutrients and organic materials in these coastal waters.     

Environmental estrogenic effects and gonadal development in wild goldfish (Carassius auratus)

Serum vitellogenin (VTG) contents of wild goldfish (Carassius auratus) were investigated as a sensitive biomarker for artificial estrogenic compounds in aquatic environments. Goldfish was sampled from a pristine area, a river situated 5 km downstream from a sewage treatment works (STW), and also from the Young-San River in Korea. The female yolk precursor protein VTG was not detected when gonadosomatic index (GSI) was less than 0.85%, while VTG levels of >10 microg/ml were found in males whose GSI was less than 1.53%. In male goldfish sampled from STW and the Young-San River, the higher VTG corresponded to lower GSI. This study suggested a trend that gonad development was connected to VTG levels in both sexes, and the application of GSI and histological analysis provide an attractive possibility that it could be included in the panel of markers used for estrogenic activity investigation of aquatic environments.