Characteristics of Asian dust transport based on synoptic meteorological analysis over Korea

Classification of synoptic patterns and their correlation with dust events over East Asia were performed by means of cluster analysis. The average linkage and K-means clustering techniques were used to identify two major weather types during Asian dust events (ADEs; total 26 ADEs with 47 dusty days) of six spring seasons from 1996 to 2001. The first weather type mainly influenced neighboring Asian countries and frequently occurred with ADEs (approximately 23% of ADE cases). It mostly occurred under a surface high (low)-pressure system over the west (east) of the Korean peninsula coupled with an upper-level trough and cutoff low passage over the center of the Korean peninsula. It showed strong advection in the middle/ upper troposphere with both a high aerosol index and enhanced coarse particulate matter (PM) loading over Korea. In contrast, the second weather type was mostly associated with long distance or continental-scale transport and occurred less frequently with ADEs (approximately 15%). It appeared with an upper-level trough and a cutoff low vertically connected with a surface low system that was formed by a strong cyclonic vortex over the north of the Korean peninsula. There were weak advection, low aerosol index, and low coarse PM concentration over the Korean peninsula during the second weather type. In addition, it was found to be mostly associated with the trans-Pacific transport of Asian dust to the western coast of North America.     

Patterns of serum PCDD/Fs affected by vegetarian regime and consumption of local food for residents living near municipal waste incinerators from Taiwan

The aim of this study was to evaluate possible factors affecting serum polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) levels of people living near municipal waste incinerators (MWIs). We selected 19 MWIs in Taiwan and collected 1708 serum samples from residents 18-65 years old who had lived within 5 km of one of the selected MWIs for at least 5 years. The samples were analyzed using a standardized study protocol to assure comparability of the concentrations from 17 PCDD/F congeners. The results suggested that a vegetarian regimen was a protective factor to avoid serum PCDD/F accumulation in the subjects. In addition, the current data seemed to support the hypothesis that serum PCDD/F levels of residents living near MWIs are related to they consumed the locally grown or cultivated vegetable and animal foods, such as poultry products near the MWIs. Our results can be used to create guidelines for preventing excessive PCDD/F accumulation from eating animal and vegetable foods grown near MWIs.     

Multi-technique characterization of a nuclear bomb particle from the Palomares accident

A January 1966 accident dispersed Pu and other nuclear bomb materials in the vicinity of Palomares, a village in southeastern Spain. Radioactive particles were identified in a soil sample collected in 1998 and analytical results obtained from one of the isolated particles are presented here. Isolation of the particle was performed using gamma-ray spectrometry and imaging plates. Scanning electron microscopy with X-ray microanalysis revealed the presence of U and Pu as well as Pb and Fe in the particle of approximately 10microm diameter. Radioisotopes of U, Pu, and Am were quantified using radiometric methods, inductively coupled plasma mass spectrometry and secondary ion mass spectrometry. The elevated (235)U/(238)U atom ratio indicates enriched U, and the Pu atom ratios are consistent with weapons-grade material. This work demonstrates that the analysis of individual particles provides information not available through bulk sample analysis.     

The study of ultrasound-assisted oxidative desulfurization process applied to the utilization of pyrolysis oil from waste tires

In recent years, the increasing world population and rapid industrial development has increased the consumption of fossil fuel-derived oils. In response to the resulting exhaustion of fossil fuel energy, many countries around the world are investigating methods of waste energy recovery and reuse, including oil recovery from the pyrolysis process of waste tires. This study investigates the efficiency of an ultrasound-assisted oxidative desulfurization (UAOD) process in sulfur reduction from diesel oil and the pyrolysis oil from waste tires treatment. The results indicate that the oxidation efficiency increases as the doses of transition metal catalyst are increased. Longer sonication time also enhances the oxidation process, apparently through the biphasic transfer of oxidants, which results in a high yield of organic sulfur oxidation products. The best desulfurization efficiency was 99.7% (2.67 ppm sulfur remaining) and 89% (800 ppm sulfur remaining) for diesel and pyrolysis oils, respectively, via a process executed by two UAOD units connected in series and combined with solid adsorption using 30 g of Al₂O₃ in 6 cm columns. These batch experiment results demonstrate clean waste energy recovery and utilization, while fulfilling the requirements of Taiwan EPA environmental regulations (sulfur concentrations less than 5000 ppm).     

Synthesis of mesoporous magnesium oxide: Its application to CO2 chemisorption

Mesoporous magnesium oxide (MgO) was synthesized using mesoporous carbon CMK-3 obtained from mesoporous SBA-15 as exotemplate. P123 was used as the structure-directing template and rice husk ash (RHA) as the silica source for the synthesis of SBA-15, which was subsequently treated with sucrose and sulphuric acid to obtain mesoporous carbon (CMK-3). X-ray powder diffraction (XRD) results and the type-IV adsorption isotherm with H1 hysteresis obtained by N₂ adsorption/desorption study for SBA-15, CMK-3 and mesoporous MgO suggests its resemblance with materials synthesized using conventional silica sources. Mesoporous MgO was subjected for CO₂ adsorption study in TGA; adsorption was 8 and 10 wt% at 25 and 100 °C, respectively. Finally, mesoporous MgO is selective to CO₂ gas, thermally stable and regenerable. Thus, this study contributes a better route to enhance CO₂ gas adsorption and use ecological waste rice husk for the synthesis of such efficient mesoporous materials.