Stable isotope on the evaluation of water quality in the presence of WWTPs in rivers

Environmental Science and Pollution Research - We investigated the distribution of nitrogen compounds in Han River as well as two tributaries of Tancheon and Jungrangcheon. Particularly, we...     

A comparative study on per capita waste generation according to a waste collecting system in Korea

As cities are becoming increasingly aware of problems related to conventional mobile collection systems, automated pipeline-based vacuum collection (AVAC) systems have been introduced in some densely populated urban areas. The reasons are that in addition to cost savings, AVAC systems can be efficient, hygienic, and environmentally friendly. Despite difficulties in making direct comparisons of municipal waste between a conventional mobile collection system and an AVAC system, it is meaningful to measure the quantities in each of these collection methods either in total or on a per capita generation of waste (PCGW, g/(day*capita)) basis. Thus, the aim of this study was to assess the difference in per capita generation of household waste according to the different waste collection methods in Korea. Observations on household waste show that there were considerable differences according to waste collection methods. The value of per capita generation of food waste (PCGF) indicates that a person in a city using AVAC produces 60 % of PCGF (109.58 g/(day*capita)), on average, compared with that of a truck system (173.10 g/(day*capita)) as well as 23 %p less moisture component than that with trucks. The value of per capita generation of general waste (PCGG) in a city with an AVAC system showed 147.73 g/(day*capita), which is 20 % less than that with trucks delivered (185 g/(day*capita)). However, general waste sampled from AVAC showed a 35 %p increased moisture content versus truck delivery.     

UV Spectroscopic Monitoring of Vaporized Monoaromatic Hydrocarbons from Petroleum-Contaminated Soils

Fast and simple systems using ultraviolet (UV) absorbance were examined for on-line monitoring of monoaromatic hydrocarbons from petroleum-contaminated soils in this research. Since soil particles hinder the UV light transmittance, the absorbance measurement of vaporized monoaromatic hydrocarbons in soil gas extracted from petroleum-contaminated soils was proposed. In the fixed system that exhibited higher sensitivity than the portable one, the absorbance intensity of benzene, toluene, ethylbenzene, and xylene increased in proportion to the concentration of the contaminants. The portable system, however, was suitable for screening purpose, while it exhibited faster response. There was no interference from water, which helps the applicability of the proposed systems to the actual fields.     

Gender differences in public office workers’ satisfaction,subjective symptoms and musculoskeletal complaints in workplace and office environments

This study investigates differences between male and female public office workers’ satisfaction levels, sick building syndrome (SBS) symptoms and musculoskeletal disorder (MSD) complaints in workplace and office environments. Questionnaire surveys were performed in 30 offices from 15 public institutions. Male and female workers of the same age were coupled and selected from each office, gathering a total of 120 male and 120 female subjects. The results show that differences exist between genders in noise and lighting satisfaction levels, SBS-related symptoms (eye, nose, skin) and MSD complaints of hand/wrist/finger, while there is no difference in overall satisfaction level of office environments. The study also suggests that office design for public office workers should take into account gender differences in preventing MSDs and also SBS. The findings of this study are expected to serve as basic data for designing effective public office environments.     

Flux measurements of volatile organic compounds by the relaxed eddy accumulation method combined with a GC-FID system in urban Houston,Texas

A tall tower flux measurement setup was established in metropolitan Houston, Texas, to measure trace gas fluxes from emission sources in the urban surface layer. We describe a new relaxed eddy accumulation (REA) system combined with a dual-channel GC-FID used for VOC flux measurements, focusing on benzene, toluene, ethylbenzene and xylenes (BTEX) results. Ambient air sampled from 60 m above the ground next to a sonic anemometer was subsampled by a membrane pump and pushed into an REA valve system with two Teflon bag reservoirs, then transferred to two preconcentration units for thermal desorption. We discuss the performance of our system and the selected BTEX measurement results using approximately 8 weeks of data (May 22–July 22, 2008), presenting diurnal variations of concentrations and fluxes of these traffic tracers. The measured values exhibited diurnal cycles with dominant morning and midday peaks during weekdays related to rush hour traffic and additional weekday daytime toluene and xylenes emissions. Local evaporative emissions, likely from solvent usage, significantly contributed to the measured fluxes. We upscaled measured emissions to the county level using a high resolution land cover data set and compared the results with EPA’s National Emission Inventory (NEI).     

Relative importance of polychlorinated naphthalenes compared to dioxins, and polychlorinated biphenyls in human serum from Korea: Contribution to TEQs and potential sources

Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) in human have been studied extensively; however, polychlorinated naphthalenes (PCNs) have been studied less widely. The mean concentrations of PCNs, PCDDs, PCDFs, and PCBs in 61 healthy human volunteers were 2170 pg/g lipid, 452 pg/g lipid, 116 pg/g lipid, and 120 ng/g lipid respectively, and the mean toxic equivalents (TEQs) contributed by PCNs, PCDDs, PCDFs, and PCBs were 5.88, 5.22, 5.48, and 5.33 pg/g lipid, respectively. PCNs contributed to 26.8% of the total TEQs. 1,2,3,7,8-PeCDD, 2,3,4,7,8-PeCDF, PCB126, and hepta-CN-73 accounted for >62% of the total TEQs in the human serum samples. The overall serum PCN homologue profiles of all subjects were dominated by tetra- and penta-CN homologues, and the most predominant individual congener was hepta-CN-73, which contributed 17.5% of the total serum PCN concentration. Enrichment of hepta-CN-73 in the human serum samples might be due to contributors from combustion sources.     

A contribution of brown carbon aerosol to the aerosol light absorption and its radiative forcing in East Asia

Brown carbon aerosols were recently found to be ubiquitous and effectively absorb solar radiation. We use a 3-D global chemical transport model (GEOS-Chem) together with aircraft and ground based observations from the TRACE-P and the ACE-Asia campaigns to examine the contribution of brown carbon aerosol to the aerosol light absorption and its climatic implication over East Asia in spring 2001. We estimated brown carbon aerosol concentrations in the model using the mass ratio of brown carbon to black carbon (BC) aerosols based on measurements in China and Europe. The comparison of simulated versus observed aerosol light absorption showed that the model accounting for brown carbon aerosol resulted in a better agreement with the observations in East Asian-Pacific outflow. We then used the model results to compute the radiative forcing of brown carbon, which amounts up to ?2.4 W m^?2 and 0.24 W m^?2 at the surface and at the top of the atmosphere (TOA), respectively, over East Asia. Mean radiative forcing of brown carbon aerosol is ?0.43 W m^?2 and 0.05 W m^?2 at the surface and at the TOA, accounting for about 15% of total radiative forcing (?2.2 W m^?2 and 0.33 W m^?2) by absorbing aerosols (BC + brown carbon aerosol), having a significant climatic implication in East Asia.