Risk Analysis of Volatile Organic Compounds Through Daily Life Cycle in the Industrial City in Korea

This study analyzed the risk of exposure to volatile organic compounds (VOCs) through a study of activity patterns in the Korean industrial city, Ulsan. The daily life cycle patterns(LCPs) of 331 people in Ulsan were surveyed and the average LCPs in Ulsan were obtained by statistical analysis. Nine to twelve personal air samples of VOC exposure at the breathing zones were collected at each LCP. This included hours for sleeping,cooking and eating, going to and from work, working, participating in field or outdoor activities, reading, watchingTV, and shopping. The components and concentrations of the collected VOCs were identified by a Gas Chromatography-MassDetector (GC-MS). The overall reproducibility of all GC analytical procedures of the simultaneously collected duplicatesample pairs represented a mean of percent differences rangingfrom about 9 to 13%. For the general population of Ulsan, thecarcinogenic and non-carcinogenic risk of exposure to theVOCs during the LCPs was evaluated. The carcinogenic riskwas analyzed using both the chronic daily exposure orlifetime average daily exposure (CDI) and the cancerpotency factor. The non-carcinogenic risk was analyzedusing both the CDI and the chronic reference dose.The major chemical forms of the identified VOCs were oxidized forms (43%), aliphatic alkanes (29%) and aromatics (15%). Even though the highest total exposure strength per unit time of each activity was observed during shopping, the highest totalamount of exposure to VOCs was identified as the exposure duringwork. The total carcinogenic risk of exposure to the carcinogenicVOCs through daily life cycle in Ulsan was 2.0 × 10^-4which is substantially exceeding the permissible carcinogenicrisk level, 10^-5 10^-6. The carcinogenic riskduring most of the life cycle activities, except forreading, mainly performed indoors, was higher than that ofthe activities performed outdoors. The carcinogenic risk bybenzene exposure was about 56% (time weighted average) ofthe total carcinogenic risk by the exposure to thecarcinogenic VOCs. During cooking and eating, shopping andout door activities, however, the carcinogenic risk by theexposure to chlorinated compounds like chloroform exceededthe exposure to benzene. The overall hazard index (non-carcinogenic risk) by a chronic exposure to carcinogenicand non-carcinogenic VOCs through daily life cycle in Ulsanwas evaluated as 3.91 × 10^-1, which is much less than1.0 considered as a hazard level to human health, and thusit seems likely not to produce a severe health hazard.     

Oxidation of organophosphorus pesticides for the sensitive detection by a cholinesterase-based biosensor

A potentiometric flow injection-type biosensor developed in our laboratory was used for the determination of organophosphorus pesticides (OPs). The principle of the biosensor is that the degree of inhibition of a sensor enzyme by an OP is dependent on the concentration of the pesticide. The sensor system consisted of a reactor with acetylcholinesterase (AChE) immobilized on a controlled pore glass and a detector with a tubular H(+)-selective membrane electrode. In order to examine the possibility of enhancing the sensitivity of the sensor by converting OPs to oxidized forms (stronger inhibitors), a comparison of the degree of enzyme inhibition by OPs at 10(-6) M before and after their oxidation was made. All of the ten pesticides tested exhibited greater inhibitory power toward the sensor enzyme following oxidation. All of the oxidized pesticides at 10(-6) M inhibited the sensor enzyme to a considerable degree, demonstrating the utility of the developed method for the class-specific determination of OPs. A calibration curve for diazinon, over the concentration range of 10(-11)-10(-4) M, was obtained. The lower detection limit was 2 x 10(-10) M. Treatment of the inhibited enzyme with pyridine-2-aldoxime restored the enzyme to near full activity, allowing repeated use of the sensor.     

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.     

Fetal marfan syndrome: Prenatal ultrasound diagnosis with pathological confirmation of skeletal and aortic lesions

Sonography was performed during the second trimester in two pregnancies at risk for the Marfan syndrome. In one, the limbs were significantly longer than expected (p < 0·0025) and a diagnosis of the Marfan syndrome was established. Pathological examination of the fetus after pregnancy interruption showed typical foci of cystic medial necrosis in the ascending aorta.     

Pretreatment of sludge with microwaves for pathogen destruction and improved anaerobic digestion performance.

A new way of generating Class A sludge using microwaves was evaluated through a series of laboratory-scale experiments. Microwaves provide rapid and uniform heating throughout the material. Other benefits of microwave treatment include instant and accurate control and selective and concentrated heating on materials, such as sludge, that have a high dielectric loss factor. Sludge was irradiated with 2450-MHz microwaves, and fecal coliforms were counted. Fecal coliforms were not detected at 65 degrees C for primary sludge and anaerobic digester sludge and at 85 degrees C for waste activated sludge when sludge was irradiated with 2450-MHz microwaves. During the bench-scale anaerobic digester operation, the highest average log reduction of fecal coliforms was achieved by the anaerobic digester fed with microwave-pretreated sludge (> or = 2.66 log removal). The anaerobic digester fed with microwave-irradiated sludge was more efficient in inactivation of fecal coliforms than the other two digesters fed with raw sludge and externally heated sludge, respectively. It took more than three hydraulic retention times for a bench-scale mesophilic anaerobic digester to meet Class A sludge requirements after feeding microwave-irradiated sludge. Class A sludge can be produced consistently with a continuously fed mesophilic anaerobic digester if sludge is pretreated with microwaves to reach 65 degrees C.     

A direct passive method for measuring water and contaminant fluxes in porous media

This paper introduces a new direct method for measuring water and contaminant fluxes in porous media. The method uses a passive flux meter (PFM), which is essentially a self-contained permeable unit properly sized to fit tightly in a screened well or boring. The meter is designed to accommodate a mixed medium of hydrophobic and/or hydrophilic permeable sorbents, which retain dissolved organic/inorganic contaminants present in the groundwater flowing passively through the meter. The contaminant mass intercepted and retained on the sorbent is used to quantify cumulative contaminant mass flux. The sorptive matrix is also impregnated with known amounts of one or more water soluble 'resident tracers'. These tracers are displaced from the sorbent at rates proportional to the groundwater flux; hence, in the current meter design, the resident tracers are used to quantify cumulative groundwater flux. Theory is presented and quantitative tools are developed to interpret the water flux from tracers possessing linear and nonlinear elution profiles. The same theory is extended to derive functional relationships useful for quantifying cumulative contaminant mass flux. To validate theory and demonstrate the passive flux meter, results of multiple box-aquifer experiments are presented and discussed. From these experiments, it is seen that accurate water flux measurements are obtained when the tracer used in calculations resides in the meter at levels representing 20 to 70 percent of the initial condition. 2,4-Dimethyl-3-pentanol (DMP) is used as a surrogate groundwater contaminant in the box aquifer experiments. Cumulative DMP fluxes are measured within 5% of known fluxes. The accuracy of these estimates generally increases with the total volume of water intercepted.     

The effect of positive work reflection during leisure time on affective well‐being: Results from three diary studies

Previous research showed that psychological detachment from work during leisure time is beneficial and that reflecting on negative aspects of work is detrimental for employees' well‐being. However, little is known about the role of positive reflection about work during leisure time. In the present research, we examined the effects of positive work reflection on affective well‐being. Additionally, we tested the effectiveness of an intervention to increase positive work reflection and to improve well‐being with a randomized controlled field experiment. Findings from three diary studies showed that positive work reflection was related to an increase in affective well‐being with regard to both positive and negative moods. The results further indicated that the benefits of positive work reflection were incremental to that of psychological detachment and the absence of negative work reflection. Contrary to our expectation, no evidence was found for the effectiveness of the intervention. Theoretical implications of main findings as well as supplementary findings are further discussed. Copyright © 2015 John Wiley & Sons, Ltd.     

Microbial Degradation of PCBs in Contaminated Sediments

The extent of natural dechlorination varies widely in sediments and fails to reach its maximum potential. Recent laboratory and field studies have suggested that the potential for further dechlorination is low in the Hudson and St. Lawrence Rivers. Laboratory investigations have also indicated that polychlorinated biphenyl (PCB) dechlorination is directly coupled to the growth of dechlorinating microorganisms in that: (a) there was no growth of dechlorinating microorganisms below the threshold concentration, (b) the rate of chlorine removal per gram sediment was significantly correlated to the growth rate of the microorganisms, (c) the negative effect of lower moisture levels on dechlorination was correlated to the microorganism death rate, and (d) the extent of natural dechlorination in the St. Lawrence River appears to be related to the in-situ population size of dechlorinators. There also appear to be many dechlorinating populations, each with different requirements and competence. Therefore, the growth enhancement of these microorganisms is the key to promoting PCB dechlorination either in situ or ex situ. © 1999 John Wiley & Sons, Inc.     

Controlling various contaminants in wastewater effluent through membranes and engineered wetland

For effective wastewater reclamation and water recovery, the treatment of natural and effluent organic matters (NOM and EfOM), toxic anions, and micropollutants was considered in this work. Two different NOM (humic acid of the Suwannee River, and NOM of US and Youngsan River, Korea), and one EfOM from the Damyang wastewater treatment plant, Korea, were selected for investigating the removal efficiencies of tight nanofiltration (NF) and ultrafiltration (UF) membranes with different properties. Nitrate, bromate, and perchlorate were selected as target toxic anions due to their well known high toxicities. Tri-(2-chloroethyl)-phosphate (TCEP), oxybenzone, and caffeine, due to their different K _ow and pK _a values, were selected as target micropollutants. As expected, the NF membranes provided high removal efficiencies in terms of all the tested contaminants, and the UF membrane provided fairly high removal efficiencies for anions (except for nitrate) and the relatively hydrophobic micropollutant, oxybenzon. Through the wetlands, nitrate was successfully removed. Therefore, a fair process of combining membranes with an engineered wetland could be proposed for sustainable wastewater reclamation and optimum control of contaminats.