Provenances of atmospheric dust over Korea from Sr–Nd isotopes and rare earth elements in early 2006

Sr and Nd isotopic composition of pre- and syn-Asian dust (Hwangsa) particles collected from three different water depths at two different offshore sites, western Korea and rare earth elemental composition of syn-Asian dust particles collected from three islands around the Korean Peninsula in late April 2006 were analyzed to interpret their provenance. The dust Sr–Nd isotopic compositions vary spatiotemporally, but they show specific values when the Hwangsa event occurred. Satellite images, airmass backward trajectory modeling, and comparison with Sr–Nd isotopic ratios and rare earth elements compositions of soils and desert sands of northern China all suggest the major source of dust particles for the late April 2006 Hwangsa event to be the Mu Us Desert in northern China. Dust particles of the pre-Hwangsa period include both background dusts and the previous Hwangsa event dust particles, and they are interpreted to have been originated from various arid regions of China such as the Hobq Desert, the Mu Us Desert, and the Taklamakan Desert in different times. Different background dust sources during pre-Hwangsa period in early 2006 resulted from the changing route of the westerlies.     

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.     

Hybridization of the natural antibiotic, cinnamic acid, with layered double hydroxides (LDH) as green pesticide

Background, aim, and scope  

Heavy application of highly toxic synthetic pesticides has been committed to protect crops against insects and diseases, which have brought about serious environmental problems. Thus, an inevitable and fundamental issue has been how to protect crops without harmful effects on nature. As a fascinating nature-compatible approach, we have attempted to hybridize soil-compatible layered double hydroxides (LDHs) with natural antibiotic substances. Only a few of natural antibiotic substances are available for pest control mainly because of their inherent properties such as easy degradability, high minimum inhibition concentration for practical application, and often extremely low availability, whereas LDHs exhibit unique properties such as anion exchange capacity, acid lability, and high affinity to ubiquitous carbonate ion which make them an excellent inorganic matrix to carry labile biomolecules in soils. This study focuses on the behavior of cinnamate–LDH hybrid in soils and the evaluation of its potentials as a green pesticide.     

Degradation of hexane and other recalcitrant hydrocarbons by a novel isolate, <Emphasis Type=Italic>Rhodococcus</Emphasis> sp. EH831

Background, aim, and scope  

Hexane, a representative VOC, is used as a solvent for extraction and as an ingredient in gasoline. The degradation of hexane by bacteria is relatively slow due to its low solubility. Moreover, the biodegradation pathway of hexane under aerobic conditions remains to be investigated; therefore, a study relating to aerobic biodegradation mechanisms is required. Consequently, in this study, an effective hexane degrader was isolated and the biodegradation pathway examined for the first time. In addition, the degradation characteristics of a variety of recalcitrant hydrocarbons were qualitatively and quantitatively investigated using the isolate.     

Emission estimation and congener-specific characterization of polybrominated diphenyl ethers from various stationary and mobile sources

Here we show that combustion sources, including waste incinerators, metallurgical processes, power-heating systems and so on, are also important emitters of polybrominated diphenyl ethers (PBDEs) to the atmosphere. Geometric mean PBDE concentrations in the stack flue gases of the combustion sources ranged from 8.07 to 469 ng/Nm³. The sinter plants (24.7 mg/h), electric arc furnaces (EAFs) (11.3 mg/h) and power plants (50.8 mg/h) possessed the largest PBDE emission rates, which were several orders higher than those of the other reported sources. The occurrences of the PBDEs in the flue gases of the power plants and vehicles, as well as their PBDE concentrations statistically highly correlated with combustion-originated PCDD/Fs, revealing that PBDEs should be the products of combustion. The ranking of major PBDE emission sources in Taiwanese PBDE inventory for combustion sources was power plants (30.85 kg/year), vehicles (14.9 kg/year) and metallurgical processes (5.88 kg/year).     

Optimized contaminated land investigation at minimum overall cost to achieve fitness-for-purpose

A methodology for optimized contaminated land investigation (OCLI) is described that balances the uncertainty of measurements against the cost of taking the measurements and the financial losses that may arise from misclassification of the land. Uncertainty from the sources of both field sampling and chemical analysis is estimated using existing techniques, based on the taking of duplicated samples. The actual costs of sampling and analysis and the expected costs that could arise from either 'false positive' or 'false negative' classification of areas of land were estimated. A loss function was constructed that calculates the expectation of financial loss that will arise for a given uncertainty of measurement. The function shows a clear minimum value of cost at an optimal value of uncertainty. Application of this OCLI technique to two case studies demonstrated this minimum value. Below the optimum value of uncertainty, the costs increased due to higher measurement costs. Above the optimum, the costs increased due to increasing risk of factors such as unnecessary remediation or potential litigation over undetected contamination. Many areas for further development of OCLI are identified, but the technique is demonstrated as a useful new approach to judging fitness-for-purpose of such measurements.     

Regeneration of used sand with sodium silicate binder by wet method and their core manufacturing

Journal of Material Cycles and Waste Management - Organic binders that are used in sand casting emit high amounts of hazardous pollutants and volatile organic compounds during the casting process....     

Heavy metals,occurrence and toxicity for plants: a review

Metal contamination issues are becoming increasingly common in India and elsewhere, with many documented cases of metal toxicity in mining industries, foundries, smelters, coal-burning power plants and agriculture. Heavy metals, such as cadmium, copper, lead, chromium and mercury are major environmental pollutants, particularly in areas with high anthropogenic pressure. Heavy metal accumulation in soils is of concern in agricultural production due to the adverse effects on food safety and marketability, crop growth due to phytotoxicity, and environmental health of soil organisms. The influence of plants and their metabolic activities affects the geological and biological redistribution of heavy metals through pollution of the air, water and soil. This article details the range of heavy metals, their occurrence and toxicity for plants. Metal toxicity has high impact and relevance to plants and consequently it affects the ecosystem, where the plants form an integral component. Plants growing in metal-polluted sites exhibit altered metabolism, growth reduction, lower biomass production and metal accumulation. Various physiological and biochemical processes in plants are affected by metals. The contemporary investigations into toxicity and tolerance in metal-stressed plants are prompted by the growing metal pollution in the environment. A few metals, including copper, manganese, cobalt, zinc and chromium are, however, essential to plant metabolism in trace amounts. It is only when metals are present in bioavailable forms and at excessive levels, they have the potential to become toxic to plants. This review focuses mainly on zinc, cadmium, copper, mercury, chromium, lead, arsenic, cobalt, nickel, manganese and iron.     

Arsenic mobility in the amended mine tailings and its impact on soil enzyme activity

The objectives of this study were to elucidate the effects of soil amendments [Ferrous sulfate (Fe^II), red mud, Fe^II with calcium carbonate (Fe^II/L) or red mud (RM/F), zero-valent iron (ZVI), furnace slag, spent mushroom waste and by-product fertilizer] on arsenic (As) stabilization and to establish relationships between soil properties, As fractions and soil enzyme activities in amended As-rich gold mine tailings (Kangwon and Keumkey). Following the application of amendments, a sequential extraction test and evaluation of the soil enzyme activities (dehydrogenase and β-glucosidase) were conducted. Weak and negative relationships were observed between water-soluble As fractions (As_WS) and oxalate extractable iron, while As_WS was mainly affected by dissolved organic carbon in alkaline tailings sample (Kangwon) and by soil pH in acidic tailings sample (Keumkey). The soil enzyme activities in both tailings were mainly associated with As_WS. Principal component and multiple regression analyses confirmed that As_WS was the most important factor to soil enzyme activities. However, with some of the treatments in Keumkey, contrary results were observed due to increased water-soluble heavy metals and carbon sources. In conclusion, our results suggest that to simultaneously achieve decreased As_WS and increased soil enzyme activities, Kangwon tailings should be amended with Fe^II, Fe^II/L or ZVI, while only ZVI or RM/F would be suitable for Keumkey tailings. Despite the limitations of specific soil samples, this result can be expected to provide useful information on developing a successful remediation strategy of As-contaminated soils.     

Landscape-level influences of terrestrial snake occupancy within the southeastern United States

Habitat loss and degradation are thought to be the primary drivers of species extirpations, but for many species we have little information regarding specific habitats that influence occupancy. Snakes are of conservation concern throughout North America, but effective management and conservation are hindered by a lack of basic natural history information and the small number of large-scale studies designed to assess general population trends. To address this information gap, we compiled detection/nondetection data for 13 large terrestrial species from 449 traps located across the southeastern United States, and we characterized the land cover surrounding each trap at multiple spatial scales (250-, 500-, and 1000-m buffers). We used occupancy modeling, while accounting for heterogeneity in detection probability, to identify habitat variables that were influential in determining the presence of a particular species. We evaluated 12 competing models for each species, representing various hypotheses pertaining to important habitat features for terrestrial snakes. Overall, considerable interspecific variation existed in important habitat variables and relevant spatial scales. For example, kingsnakes (Lampropeltis getula) were negatively associated with evergreen forests, whereas Louisiana pinesnake (Pituophis ruthveni) occupancy increased with increasing coverage of this forest type. Some species were positively associated with grassland and scrub/shrub (e.g., Slowinski's cornsnake, Elaphe slowinskii) whereas others, (e.g., copperhead, Agkistrodon contortrix, and eastern diamond-backed rattlesnake, Crotalus adamanteus) were positively associated with forested habitats. Although the species that we studied may persist in varied landscapes other than those we identified as important, our data were collected in relatively undeveloped areas. Thus, our findings may be relevant when generating conservation plans or restoration goals. Maintaining or restoring landscapes that are most consistent with the ancestral habitat preferences of terrestrial snake assemblages will require a diverse habitat matrix over large spatial scales.