Monitoring and risk assessment of polychlorinated biphenyls (PCBs) in agricultural soil from two industrialized areas

For monitoring and risk assessment, levels and distributions of Σ₂₉ PCBs in paddy soil samples collected from Gwangyang (10 sites) and Ulsan (20 sites), heavily industrialized cities in Korea, were investigated using high-resolution gas chromatography/high-resolution mass spectrometry. Overall, total concentrations of Σ₂₉ PCBs in Gwangyang (216.4–978.6 pg g^?1 dw) and Ulsan (273.8–1824.1 pg g^?1 dw) were higher than those (106.6–222.6 pg g^?1 dw) in agricultural soil from Anseong in Korea. The TEQ (toxic equivalency) values from Gwangyang (0.06–0.40 ng TEQ kg^?1 dw) and Ulsan (0.06–0.22 ng TEQ kg^?1 dw) were higher than those (0.04–0.11 ng TEQ kg^?1 dw) in Anseong but lower than the WHO threshold level (20 ng TEQ kg^?1). However, one of the most toxic congeners, PCB 126, gave the highest concentration, possibly posing a risk to the biota. Seven indicator PCB congeners contributed to 50–80% of the total concentration of Σ₂₉ PCBs, indicating the 7 PCBs can be used as valuable indicators for monitoring. The principal component analysis and cluster analysis for the homologue profiles of PCBs indicated that all the samples from both cities had the similar PCB contamination patterns, and the major sources of the PCB contamination were most likely from the usage of Aroclor 1254 than those of Aroclors 1242 and 1260. These PCB technical mixtures were possibly significantly used by various industries including iron and steel industries in Gwangyang and petrochemical and shipbuilding industries in Ulsan.     

Investigation of carbonyl compounds in air from various industrial emission sources

The emission concentrations of carbonyl compounds in air were quantified from a total of 195 man-made source units within 77 individual companies at a large industrial complex in Korea. The measurement data were evaluated both by absolute magnitude of concentration and by their relative contribution to malodor formation such as malodor degree (MD) derived from empirical formula. It was found that formaldehyde exhibited the highest mean concentration of 323ppb with a median value of 28.2ppb, while butyraldehyde recorded the highest contribution to odor formation with an MD value of 3.5 (186 (mean) and 9.8ppb (median)). The relative intensity of carbonyl emission, when compared by the sum of MD, showed the highest source strength from the food and beverage (industry sector) and scrubber (source unit). A comprehensive evaluation of the carbonyl data from diverse industrial facilities thus allowed us to describe the fundamental patterns of their emission.     

Analysis of volatile organic compounds released during food decaying processes

A number of volatile organic compounds (VOCs) including acetone, methyl ethyl ketone, toluene, ethylbenzene, m,p-xylene, styrene, and o- xylene released during food decaying processes were measured from three types of decaying food samples (Kimchi (KC), fresh fish (FF), and salted fish (SF)). To begin with, all the food samples were contained in a 100-mL throwaway syringe. These samples were then analyzed sequentially for up to a 14-day period. The patterns of VOC release contrasted sharply between two types of fish (FF and SF) and KC samples. A comparison of data in terms of total VOC showed that the mean values for the two fish types were in the similar magnitude with 280 ± 579 (FF) and 504 ± 1,089 ppmC (SF), while that for KC was much lower with 16.4 ± 7.6 ppmC. There were strong variations in VOC emission patterns during the food decaying processes between fishes and KC that are characterized most sensitively by such component as styrene. The overall results of this study indicate that concentration levels of the VOCs differed significantly between the food types and with the extent of decaying levels through time.     

强化混凝-氧化处理含溴氰菊酯农药水库水

通过投加不同混凝剂、助凝剂和氧化剂,对含溴氰菊酯农药的某水库原水进行强化混凝-氧化处理,探讨了不同条件下对原水的处理效果.结果表明,当对水样仅作常规混凝处理时,聚合氯化铝(PAC)的处理效果优于其他混凝剂,最佳投加量为18mg/L,最佳pH为9,最高去除率可达64.5％.投加助凝剂可提高混凝效果,聚丙烯酰胺(PAM)助凝效果优于水玻璃.混凝后水样再用高锰酸钾(KMnO4)氧化处理,结果表明,在水样pH为5,KMnO4投加量为0.6mg/L,氧化时间为25 min的条件下,溴氰菊酯去除率最高可达82.4％.     

Installation of platform screen doors and their impact on indoor air quality: Seoul subway trains

In this study, variations of particulate matter (PM) concentrations in subway trains following installation of platform screen doors (PSDs) in the Seoul subway system were investigated. PM samples were collected in the trains on subway lines 1–8 before and after installation of PSDs. It was found that the mean PM₁₀ concentration in the trains after PSDs installation increased significantly by 29.9% compared to that before installation. In particular, the increase of PM₁₀ in line 6 was the highest at 103%. When the relationship between PM₁₀ and PM_2.5 was compared, coefficients of determination (r²) before and after PSDs installations were 0.696 and 0.169, respectively. This suggests that air mixing between the platform and the tunnel after PSDs installation was extremely restricted. In addition, the indoor/outdoor PM₁₀ ratio following PSDs installation increased from 1.32 to 2.97 relative to the period with no installed PSDs. Furthermore, this study revealed that PM levels in subway trains increased significantly after all underground PSDs were put in use. Several potential factors were examined that could result in this PM increase, such as train ventilation systems, operational conditions, passenger volume, subway depth, and the length of underground segments.

ImplicationsPM₁₀ concentrations inside the subway trains increased after PSDs installation. This indicates that air quality in trains was very seriously impacted by PSDs. PM₁₀ levels were also influenced by the tunnel depth and length of the underground segments. To prevent the adverse effect on human health by PM₁₀ emitted from the tunnel, an applicable ventilation system to reduce PM₁₀ is required inside trains and tunnels.     

Selective catalytic reduction of NO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> using RDF char and municipal solid waste char based catalyst

Experiments were performed in order to investigate the possibility for the development of catalysts for low-temperature selective catalytic reduction (SCR) using municipal waste char and RDF byproduct. Physical and chemical activations, using water, and HCl and KOH, were employed to increase the catalytic activities. The characteristics of the activated catalysts were investigated using N₂ adsorption–desorption and FT-IR. The catalysts activated chemically using basic treatment showed higher NO _x removal efficiencies than those activated physically or chemically using acidic treatment. The de-NO _x performance of the activated catalysts was dependent on the chemical properties, such as oxygen functional groups as well as physical properties, such as specific surface area and pore volume. In order to investigate the effect of MnO _x , which has been reported to be efficient for the removal of NO _x in low-temperature SCR processes, the chemically activated catalyst was impregnated with manganese. The Mn-impregnated catalyst had the highest NO _x conversion at all of the temperatures tested in this study.     

Correlation study of hazardous waste characteristics among various chemical processes in Republic of Korea

To harmonize with international standards, the Republic of Korea is in the process of converting its current hazardous waste classification system and setting up regulatory standards for all toxic substances present in hazardous waste. Detailed characterization of each form of hazardous waste belonging to five chemical processes and their correlations were studied. In the present work, the concentrations of 13 heavy metals, F^?, CN^?, 7 PAH compounds, total PCDD/F and 7 PCB isomers present in the hazardous waste generated among chemical processes such as synthetic rubber (SR), man-made fibers (MF), organic dyes and pigments (DP), pharmaceuticals and cosmetics were analyzed along with their leaching characteristics. Comparing all the processes, most of the heavy metal concentrations were high in SR waste. Naphthalene was the dominant PAH in most of the chemical process waste. PCDD/F concentrations of the samples were in the range of 0.001–0.003 ng I-TEQ/g. PCB isomer-101 and isomer-118 were found to be slightly higher than the permissible limit in the SR filter cake sample. SR process wastes doesn’t show any resemblance with the other process waste in either the heavy metals and PAH trend. Each sample from DP and MF were suitable only for hazardous waste landfill.     

1H-NMR-based profiling of organic components in leachate from animal carcasses disposal site with time

Leachate, generated by the decomposition of animal carcasses, presents many environmental, sanitary, and food safety hazards. However, research on the characteristics of leachate is lacking. In this study, we performed biochemical profiling of leachate from two animal species (pig and cattle) in two soil types (sandy loam and sandy soil) using ¹H-NMR-based profiling, followed by multivariate data analysis. The leachate was collected from a well-controlled artificial burial site over a 31-week period. Principal components analysis (PCA) of the NMR data showed similar patterns between species and soil types. Organic components, including organic acids and phenols, predominated, and their levels increased with time. The methylamine level in leachate from pig carcasses 18 weeks following burial was significantly higher than that from cattle carcasses; leachate from cattle carcasses in sandy soil 1 week after burial contained unique components (specifically ethanol, formate, alanine, N-methylation, and taurine), in contrast with those from sandy loam soil. This study suggests that a NMR-based profiling approach is useful to characterize the organic components in leachate from animal carcasses over time.     

朝鲜4.13“光明星3号”卫星发射次声信号分析

朝鲜4.13"光明星3号"发射是一次包含火箭发射与爆炸次声信号的事件。对火箭发射激发次声信号的基本理论、影响火箭发射激发次声信号监测能力的因素等进行了简要阐述;在分析火箭发射历史次声信号的基础上,研究了该类信号的信号走时、频率及波形特征;对"光明星3号"发射激发的次声信号从事前预判、信号检测、爆炸区域确定、误差原因分析等方面进行了详细分析说明。研究分析结果表明:朝鲜"光明星3号"的爆炸疑似区域为北纬35.2756°～36.3887°,东经125.1675°～126.5487°。