Identification and interpretation of representative ozone distributions in association with the sea breeze from different synoptic winds over the coastal urban area in Korea

To aid the studies of long-term impact assessment of cumulative ozone (O3) exposures, the representative 8-hr O3 pollution patterns have been identified over the Greater Seoul Area (GSA) in Korea. Principal component analysis and two-stage clustering techniques were used to identify the representative O3 patterns, and numerical and observational analyses were also used to interpret the identified horizontal distribution patterns. The results yielded three major O3 distribution patterns, and each of the three patterns was found to have strong correlations with local and synoptic meteorological conditions over the GSA. For example, pattern 1, accounting for 46% of O3 concentration distributions, mostly occurred under relatively weak westerly synoptic winds. The predominant features of this pattern were infrequent high O3 levels but a distinct gradient of O3 concentration from the western coastal area to the eastern inland area that was mainly induced by the local sea breeze. Pattern 2, accounting for 31% of O3 concentration distributions, was found with higher O3 levels in the western coastal area but lower in the eastern inland area. This is due to the modified sea breeze under the relatively stronger easterly opposing synoptic wind, affecting the high O3 occurrence in the western coastal area only. However, pattern 3, accounting for 21% of O3 concentration distributions, showed significantly higher O3 concentrations over the whole GSA mainly due to the retarded and slow-moving sea-breeze front under the weak opposing synoptic flow. Modeling study also indicated that local and synoptic meteorological processes play a major role in determining the high O3 concentration distribution patterns over the GSA.     

Estrogen equivalent concentration of 13 branched para-nonylphenols in three technical mixtures by isomer-specific determination using their synthetic standards in SIM mode with GC-MS and two new diasteromeric isomers

Thirteen isomers of branched para-nonylphenols (para-NP) in three technical mixtures were isomer-specifically determined using their synthesized standards by SIM of structurally specific ions, m/z 135, 149 or 163 with GC–MS. Of the 13 isomers, four isomers, 4-(2,4-dimethylheptan-4-yl)phenol, 4-(4-methyloctan-4-yl)phenol, 4-(3-ethyl-2-methylhexan-2-yl)phenol (3E22NP) and 4-(2,3-dimethylheptan-2-yl)phenol synthesized for their determinations were first used as standard substances. The 13 isomers in the technical mixtures individually occurred at mass percent portion of more than 2%. The total mass percent portions in the mixtures from Tokyo Chemical Industry (TCI), Aldrich, and Fluka covered with 89 ± 2%, 75 ± 4% and 77 ± 2%, respectively. The abundance of 4-(3,6-dimethylheptan-3-yl)phenol in the three mixtures was the largest with 11.1 ± 2% to 9.9 ± 0.3%, while that of 4-(2-methyloctan-2-yl)phenol was the smallest with 2.9 ± 0.3% to 3.0 ± 0.2%. Additionally, structures of four new isomers of more than 1% portion present in a technical mixture were elucidated as two pairs of diastereomeric isomers: two types of 4-(3,4-dimethylheptan-4-yl)phenol (344NP) and those of 4-(3,4-dimethylheptan-3-yl)phenol (343NP). By estrogenic assay of 13 isomers with yeast estrogen screen system, the activity of 3E22NP was the highest, while that of 4-(3-methyloctan-3-yl)phenol was the least. Their relative activities to that of 3E22NP were individually calculated. Estrogenic equivalent concentrations of the three technical mixtures were predictively evaluated. The ratio of the EEC to the conventional concentration, total mass percent portions of the 13 isomers in technical mixtures were 0.208 for TCI, 0.206 for Aldrich and 0.205 for Fluka. The predicted estrogenic activity of measured concentration of para-NP in technical mixtures was approximately 5-fold greater than the measured estrogen agonist activity.     

Development and application of kinetic model on biological anoxic/aerobic filter

An up-flow biological anoxic filter (BANF) has been developed to achieve high removal performance of suspended solids and BOD removal as well as nitrogen. With a view to understand treatment mechanisms, we developed a filtration model that incorporates filtration, deposit scoring and biological reactions simultaneously. The biological reactions consist of four types of reaction; dissolution of organic particles; utilization of dissolved organic matter; denitrification; and self-degradation of bacteria. Whereas the reactor is generally assumed to be a plug flow reactor in the filtration model, it is assumed a continuous-flow stirred tank reactor (CSTR) in the model of biological reactions. The hydrodynamics is supposed that the filter bottom (the portion sludge settled) is a CSTR and the filter bed (the portion filled with filter media) consists of number of CSTR of equal size arranged in series. The model obtained in this study was verified and simulated using experimental results taken from a pilot-scale plant and predicted the experimental data well, applying to design and operate BANF.     

Development of conflict techniques for left-turn and cross-traffic at protected left-turn signalized intersections

To design comprehensive traffic safety measures, the risk of the occurrence of traffic accidents must be objectively evaluated. It is difficult, however, to evaluate the effects of traffic measures in terms of the change in the number of traffic accidents, because traffic accidents are unpredictable and rare events. Therefore, this study used a traffic conflict technique to objectively evaluate traffic safety at intersections. In this study, traffic conflicts that occur at the time of a signal violation were differentiated according to type, and a traffic conflict technology was developed that would consider the severity of each type of conflict. To apply this method, traffic images were collected from the Jungja intersection and the Naejung intersection in Sungnam City, Korea and were analyzed using traffic data by means of image procedure technology. The analyses showed that of the four levels of differentiated conflict conditions, the Level 1 condition occurred most often, followed by Level 2, which occurred much less frequently than Level 1. Level 3 (serious conflicts) and Level 4 (dangerous conflicts: accidents) conditions were not detected.     

Evaluation of pliers’ grip spans in the maximum gripping task and sub-maximum cutting task

A total of 25 males participated to investigate the effects of the grip spans of pliers on the total grip force, individual finger forces and muscle activities in the maximum gripping task and wire-cutting tasks. In the maximum gripping task, results showed that the 50-mm grip span had significantly higher total grip strength than the other grip spans. In the cutting task, the 50-mm grip span also showed significantly higher grip strength than the 65-mm and 80-mm grip spans, whereas the muscle activities showed a higher value at 80-mm grip span. The ratios of cutting force to maximum grip strength were also investigated. Ratios of 30.3%, 31.3% and 41.3% were obtained by grip spans of 50-mm, 65-mm, and 80-mm, respectively. Thus, the 50-mm grip span for pliers might be recommended to provide maximum exertion in gripping tasks, as well as lower maximum-cutting force ratios in the cutting tasks.     

Mutagenic and carcinogenic potency of extracts from diesel related environmental emissions: Simultaneous morphological transformation and mutagenesis in BALB/c 3t3 cells

Particulate extracts from six different environmental emission sources were assayed for genotoxic activity in mouse BALB/c 3T3 clone A31-1 cells. All compounds were tested simultaneously for both transforming and mutagenic (induction of ouabain-resistance) potential with and without exogenous metabolic activation in the form of a 9000 × g postmitochondrial hepatic supernatant fraction from Aroclor-1254 induced Fischer 344 rats. Dichloromethane particulate extracts from the exhaust of two light duty diesel engines (Oldsmobile and Nissan), one heavy duty diesel engine (Caterpillar) and one late model gasoline engine (Mustang II) were assayed in an identical manner to particulate extracts from the emissions of a roofing tar pot and a coke oven. No clear dose-dependent responses were observed, but several of the samples showed significant transforming and mutagenic activity. A qualitative ranking system showed the activity of these particulate extracts for either mutagenesis or transformation was: coke oven = Mustang II gasoline engine > Nissan diesel engine > roofing tar. Particulate extracts from the Oldsmobile diesel engine and the Caterpillar diesel engine showed essentially no activity.     

Evaluating the e ects of granular and membrane filtrations on chlorine demand in drinking water

In this study, chlorine decay experiments were conducted for the raw water from Nakdong River that is treated by Chilseo Water Treatment Plant (CWTP) situated in Haman, Korea as well as the e uents from sand and granular activated carbon (GAC) filters of CWTP and fitted using a chlorine decay model. The model estimated the fast and slow reacting nitrogenous as well as organic/inorganic compounds that were present in the water. It was found that the chlorine demand due to fast and slow reacting (FRA and SRA) organic/inorganic substances was not reduced significantly by sand as well as GAC filters. However, the treated e uents from those filters contained FRA and SRA that are less reactive and had small reaction rate constants. For the e uents from microfiltration, ultrafiltration, and nanofiltration the chlorine demand because FRA and SRA were further reduced but the reaction rate constants were larger compared to those of sand and GAC filter e uents. This has implications in the formation of disinfection by products (DBPs). If DBPs are assumed to form due to the interactions between chlorine and SRA, then it is possible that the DBP formation potential in the e uents from membrane filtrations could be higher than that in the e uents from granular media filters.     

An investigation of methods for enriching trophoblast from maternal blood

Trophoblast deportation is known to occur in normal human pregnancy, but it is not yet clear whether these cells routinely enter the maternal peripheral circulation and are available as a source of fetal DNA for non-invasive prenatal diagnosis of genetic disorders. To resolve this issue requires an efficient method of enriching trophoblast from maternal blood combined with a means to confirm its identity. Five different techniques were tested on ten retroplacental blood samples to determine the most sensitive and operator-efficient method. Lysis of red cells alone gave the best recovery of trophoblast but had to be discounted, together with Ficoll density gradient centrifugation, due to the very low purity and the excessive time required. Fluorescence-activated cell sorting (FACS) of pre-enriched trophoblast resulted in the lowest recovery rate (8 per cent) despite a 3250-fold enrichment and a very high purity. Immunomagnetic beads (Dynabeads) coated with anti-CD 16 antibody proved to be the best method for the subsequent immunocytochemical characterization of deported trophoblast. However, IO beads coated with anti-CD45 antibody may be more useful for isolating trophoblast for prenatal diagnosis due to the high purity, enrichment (32-fold), and recovery rate (78 per cent) obtained with this method.     

Health risk assessment and source apportionment of PM2.5-bound toxic elements in the industrial city of Siheung,Korea

Environmental Science and Pollution Research - The emission sources and their health risks of fine particulate matter (PM2.5) in Siheung, Republic of Korea, were investigated as a middle-sized...     

Risk assessment of particulate matter by considering time-activity-pattern and major microenvironments for preschool children living in Seoul,South Korea

Environmental Science and Pollution Research - Preschool children aged 3–6 years are vulnerable to exposed to particulate matter (“PM10” and “PM2.5”). It is required...