Corrosion behavior of glass and glass-ceramics made of municipal solid waste incinerator fly ash

Glasses and glass-ceramics were prepared by melting municipal solid waste (MSW) incinerator fly ash and their corrosion properties were evaluated. Corrosion of both materials proceeded in two different steps. At the initial stage, the corrosion process is a diffusion-controlled process. After approximately 10 h at the initial stage, weight losses increased linearly with time due to the total dissolution of glasses or glass-ceramics. Leaching of heavy metals from glasses and glass-ceramics were well within international environmental regulations. Corrosion proceeded uniformly in fly ash glass while Na2CaSiO4 crystalline phase was preferentially dissolved in the glass-ceramics.     

Operational Atmospheric Modeling System CARIS for Effective Emergency Response Associated with Hazardous Chemical Releases in Korea

The Chemical Accidents Response Information System (CARIS) was developed at the Center for Chemical Safety Management in South Korea in order to track and predict the dispersion of hazardous chemicals in the case of an accident or terrorist attack involving chemical companies. The main objective of CARIS is to facilitate an efficient emergency response to hazardous chemical accidents by rapidly providing key information in the decision-making process. In particular, the atmospheric modeling system implemented in CARIS, which is composed of a real-time numerical weather forecasting model and an air pollution dispersion model, can be used as a tool to forecast concentrations and to provide a wide range of assessments associated with various hazardous chemicals in real time.This article introduces the components of CARIS and describes its operational modeling system. Some examples of the operational modeling system and its use for emergency preparedness are presented and discussed. Finally, this article evaluates the current numerical weather prediction model for Korea.Published online     

Novel method for determining pyrene biodegradation using synchronous fluorimetry

To study the biodegradation rate of pyrene dissolved in liquid medium supplemented with mineral salts, a synchronous fluorimetry (SF) method was established. The limit of detection for pyrene dissolved in mineral salts medium (MSM) was determined as 0.19 ng/ml with a relative standard deviation of less than 1.3% (n = 9). The pyrene degrading rates of four bacterial strains were investigated using this method under the same experimental conditions. The degradation rates of the three active strains ranged from 76% to 87% after a 14-h incubation. The results were confirmed by the gas chromatography with a flame ionized detector (GC/FID) method. This implies that pyrene degradation can be directly monitored by the SF method without the solvent extraction of samples. The advantages of SF are that it is less laborious, faster, and less expensive than the GC/FID determination method with solvent extraction. The SF method provides a new tool for studying the degradation of polynuclear aromatic hydrocarbons (PAHs) in the natural environment and under experimental conditions.     

Ecological modeling for water quality management of Kwangyang Bay, Korea

This study estimated the appropriate pollutant load reduction from point sources in Kwangyang Bay, Korea, using an eco-hydrodynamic model. The total chemical oxygen demand (COD), nitrogen (TN), and phosphorus (TP) loads from rivers and ditches that provide input to the bay were approximately 2.8x10(4), 2.5x10(4), and 5.9x10(2) kg day-1, respectively. Wastewater discharge from industrial complexes was the greatest contributor to pollutant loads in the inner part of the bay. COD values in the inner part of the bay were greater than 3.0 mg l-1, and exceeded Korean seawater quality grade III limits. A residual current was simulated, using a hydrodynamic model, to have a slightly complicated pattern in the inner part of the bay, ranging from 0.001 to 8 cm s-1. In the outer part of the bay, the simulated current flowed out to the South Sea with a southward flow at a maximum of 15 cm s-1. The results of the ecological model simulation of COD levels showed high concentrations, exceeding 4 mg l-1, in the southwest of the Myodo, an area of wastewater discharge, and lower levels, approaching less than 1 mg l-1, closer to the outer part of the bay. Engineering countermeasures to reduce the organic and inorganic material loads from point sources by more than 45% were required to keep the COD levels below 2 mg l-1.     

Cytochrome <Emphasis Type="Italic">b</Emphasis> (<Emphasis Type="Italic">Cyt-b</Emphasis>) gene sequence analysis in six flatfish species (Teleostei,Pleuronectidae), with phylogenetic and taxonomic insights

Mitochondrial DNA (mtDNA) at Cyt-b gene region was sequenced for six flatfish species (in total nine sequences of at least 1,117 bp) from the Far East of Russia and compared with other sequences of Pleuronectiformes comprising altogether 34 species and 3 outgroup species (Perciformes). Analysis of the protein-coding Cyt-b gene revealed a statistically substantiated bias in (T + C):(A + G) content, supporting earlier findings. Values of P-distances, as summarized for different scales of the evolutionary history at Cyt-b gene, revealed a clear pattern of increased nucleotide diversity at four different phylogenetic levels: (1) intraspecies, (2) intragenus, (3) intrafamily, and (4) intraorder. Scores of average P-distances of the four categories of comparison in flatfishes were (1) 0.46 ± 0.19%, (2) 11.74 ± 2.26%, (3) 17.51 ± 3.13%, and (4) 25.60 ± 0.42%, respectively (mean ± SE). These data support the concept that speciation in the order Pleuronectiformes, in most cases, follows a geographic mode through the accumulation of numerous small genetic changes over a long period of time. A phylogenetic tree for 64 sequences of flatfishes and 3 other fishes belonging to ray-finned fishes (Actinopterigii) was developed using Cyt-b gene and four different analytical approaches: neighbour-joining (NJ), Bayesian (BA), maximum parsimony (MP), and maximum likelihood (ML). The analysis revealed a monophyletic origin for the representatives of Pleuronectidae, which is the principal flatfish family investigated (99% repetition level in our BA analysis). A well supported property of the phylogenetic tree was the monophyletic placement of all the five flatfish families and the order Pleuronectiformes among other representatives of ray-finned fishes of the class Actinopterigii. Species identification on per individual basis (barcoding tagging) was generally high. However, there were taxonomic complications that arose during analysis, and they are discussed. Major outcomes of this discussion are the necessity of synonymy acceptance for Hippoglossoides elassodon, and H. robustus, and for Pseudopleuronectes yokohamae and P. schrenki. Priority considerations suggest H. elassodon and P. yokohamae as valid species names.     

Design of a water quality monitoring network in a large river system using the genetic algorithm

Despite several decades of operations and the increasing importance of water quality monitoring networks, the authorities still rely on experiential insights and subjective judgments in siting water quality monitoring stations. This study proposes an integrated technique which uses a genetic algorithm (GA) and a geographic information system (GIS) for the design of an effective water quality monitoring network in a large river system. In order to develop a design scheme, planning objectives were identified for water quality monitoring networks and corresponding fitness functions were defined using linear combinations of five selection criteria that are critical for developing a monitoring system. The criteria include the representativeness of a river system, compliance with water quality standards, supervision of water use, surveillance of pollution sources and examination of water quality changes. The fitness levels were obtained through a series of calculations of the fitness functions using GIS data. A sensitivity analysis was performed for major parameters such as the numbers of generations, population sizes and probability of crossover and mutation, in order to determine a good fitness level and convergence for optimum solutions. The proposed methodology was applied to the design of water quality monitoring networks in the Nakdong River system, in Korea. The results showed that only 35 out of 110 stations currently in operation coincide with those in the new network design, therefore indicating that the effectiveness of the current monitoring network should be carefully re-examined. From this study, it was concluded that the proposed methodology could be a useful decision support tool for the optimized design of water quality monitoring networks.     

Locating major PM10 source areas in Seoul using multivariate receptor modeling

Identifying the major sources contributing to air pollution is a problem of fundamental importance in developing effective air quality management plans. Multivariate receptor modeling aims to achieve this goal by unfolding the air pollution data into components associated with different sources based on factor analysis models. We analyze the PM₁₀ data obtained from 17 monitoring sites in Seoul to locate the major source regions using multivariate receptor modeling. The model uncertainty caused by the unknown number of sources and identifiability conditions is assessed by posterior probability of each model. The estimated source spatial profiles seem to be consistent with our prior expectation about the PM₁₀ sources in Seoul.     

Two facets of conscientiousness and the knowledge sharing dilemmas in the workplace: Contrasting moderating functions of supervisor support and coworker support

This study adopts self‐ and other‐centered approaches to explain how the two facets of conscientiousness (i.e., dutifulness and achievement striving) distinctly resolve knowledge sharing dilemmas among employees. It also explores how the critical social surroundings of employees (i.e., supervisor support and coworker support) neutralize or activate the effects of dutifulness and achievement striving on knowledge‐sharing behavior. Our analysis of the data collected from 150 employee–supervisor dyads corroborates that the other‐centered facet of conscientiousness (dutifulness) is positively related to knowledge‐sharing behavior, whereas the self‐centered facet (achievement striving) is negatively related to the same behavior. The analysis also affirms that the positive effect of dutifulness and the negative effect of achievement striving on knowledge sharing are strengthened when supervisor support is low and coworker support is high. This study offers theoretical and practical implications relevant to knowledge management in organizations, distinct roles of facet‐specific personalities toward knowledge sharing, and contrasting personality–situation interactions by situation strength and trait activation in shaping employee behavior.     

Characteristics and potential human health hazards of charged aerosols generated by high-voltage power lines

We investigated the characteristics of charged aerosols produced by high-voltage power lines (HVPLs) to explore the effects on respiratory disease incidence among those who handle HVPLs. Charged aerosol currents and charged aerosol concentrations were measured over 24?h at 12 sites. Aerosol current effective levels were 2.7 times higher compared to exposed and control sites. This pattern of relative enhancement at exposed sites was seen consistently in all measurements and the difference was 1.7 higher at exposed sites. Correlation analysis among all important variables revealed strong positive correlations between currents and concentration, currents and magnetic field, humidity and concentration, and humidity and particles of 10?µm or less (PM₁₀), while negative correlations were observed between charged aerosol concentrations and wind velocity and between wind velocity and humidity. Estimated production of charged aerosols from HVPLs found that people who work with HVPLs are highly likely to be exposed to charged aerosols.