Time filter

Source Type

Lee J.E.,National Institute of Environmental Research NIER | Lee B.U.,Konkuk University | Bae G.N.,Korea Institute of Science and Technology | Jung J.H.,Korea Institute of Science and Technology
Journal of Aerosol Science | Year: 2017

The purpose of this study was to examine the aerosolization characteristics of biocontaminated particles, including particle release behavior and the concentrations of culturable fungi and (1→3)-β-D-glucan from four flood-affected floor and bedding materials. We applied an aerosolization process using multiple air jets, then measured the particles aerosolized from biocontaminated materials in real time using an optical particle counter, while simultaneously collecting particles in a BioSampler. The total count of particles released over 10 min was highest from linoleum (25,503 particles/cm2), followed by rugs (1562 particles/cm2), carpets (508 particles/cm2), and pillows (24 particles/cm2). Linoleum, which has a hard surface, released particles the fastest (<6 s) among the test materials. During fractional particle concentration analysis, the portion of submicron particles between 0.3 and 1.0 μm was 66.1% (linoleum) – 77% (carpet) of the total particle concentration. Additionally, based on biological assays of the collected particles, the levels of culturable fungi and (1→3)-β-D-glucan in the four materials ranged from undetectable (linoleum; lower limit=0.2 CFU/cm2) to 0.83 CFU/cm2 (rug) and from 0.84 (carpet) to 3.26 ng/cm2 (rug), respectively. We suggest that these results are helpful for further understanding of the aerosolization characteristics of biocontaminated particles from flood-affected materials, with benefits for the safe restoration of flood-damaged homes. © 2017 Elsevier Ltd

Noh S.,Gwangju Institute of Science and Technology | Kim C.-K.,EH R and C Co. | Kim Y.,National Institute of Environmental Research NIER | Lee J.-H.,EH R and C Co. | Han S.,Gwangju Institute of Science and Technology
Science of the Total Environment | Year: 2016

We investigated monomethylmercury (MMHg) concentrations in 448 samples of four common fish species (barbel steed, largemouth bass, leopard mandarin, and bluegill) and the trophic states of 14 artificial reservoirs in South Korea in order to understand how trophic states of reserviors affect MMHg concentrations in fish. The trophic state index (TSI) of each reservoir was determined using empirical equations based on the monthly chlorophyll-a, total phosphorus, and Secchi depth, collected over a three-year period. The length-normalized MMHg concentrations in fish showed a negative correlation with the TSI based on chlorophyll-a (r2 =0.90) and total phosphorus (r2 =0.75) that may be a result of particle dilution of MMHg in surface waters. This study revealed that MMHg accumulation in fish was better correlated with TSI than MMHg in water, therefore, we suggest that the measurement of TSI based on chlorophyll-a and total phosphorus is an effective way to predict MMHg bioaccumulation across diverse reservoirs. © 2016.

Kim K.-H.,Korea University | Yun S.-T.,Korea University | Yun S.-T.,Korea Water Resources Corporation | Kim H.-K.,Korea University | Kim J.-W.,National Institute of Environmental Research NIER
Journal of Geochemical Exploration | Year: 2015

Increased nitrate loading of groundwater has emerged as a major environmental problem in many countries, including South Korea. This study aims to evaluate the nitrate levels of South Korean groundwater on a regional (national) scale and specifically to demonstrate the procedure to better estimate the natural background level (NBL) and threshold of nitrate as the basis of groundwater management. For this work, nitrate data of groundwater (n=8510) in two major hydrogeologic units (alluvium and bedrock) were collected from the National Groundwater Monitoring Network (NGMN) of South Korea. Four supplementary datasets (n=1074) were also used to test the rationality of estimated thresholds by comparing them with NGMN datasets. Compared with the data reported in many countries, the nitrate concentrations in NGMN groundwater in 2009 are high, with median values of 12.2 and 8.7mg/L, respectively, for alluvial groundwater and bedrock groundwater. The nitrate levels of South Korean groundwater seem to have been historically steady at these high levels between 1997 and 2009, suggesting widespread diffusive contamination since the 1980s. The NBLs and anthropogenic polluted levels (APLs) of nitrate on a regional (national) scale are statistically established by the model-based approach using a finite normal (Gaussian) two-component mixture model, because (1) the sample size (frequency) of the natural background group is much smaller than that of the polluted group, as a result of widespread nitrate contamination, and (2) nitrate concentrations are more or less affected by natural attenuation processes. Accordingly, thresholds of nitrate (as the concentration level indicating groundwater pollution) are selected as the lower limits (i.e., 10th percentile) of the polluted group, which are 3.0 and 5.5mg/L NO3 -, respectively, for bedrock groundwater and alluvial groundwater. This study provides a practical guideline for national groundwater management, based on a heuristic procedure to statistically determine the NBLs and thresholds in the case of groundwater systems with pervasive contamination. Compared with the other classical methods to estimate NBLs, the model-based approach using a finite normal-mixture model can be more effective to reasonably separate the polluted samples from a regional (or national) dataset. © 2014 Elsevier B.V.

Saro L.,Korea Institute of Geoscience and Mineral Resources | Hyun-Joo O.,Korea Institute of Geoscience and Mineral Resources | Ki-Dong K.,National Institute of Environmental Research NIER
Disaster Advances | Year: 2010

This study constructs a hazard map for ground subsidence around abandoned underground coal mines (AUCMs) at Samcheok City in Korea using a probability (frequency ratio) model, a statistical (logistic regression) model and a Geographic Information System (GIS). To evaluate the factors related to ground subsidence, an image database was constructed from a topographical map, geological map, mining tunnel map, global positioning system (GPS) data, land use map, digital elevation model (DEM) data and borehole data. An attribute database was also constructed from field investigations and reports on the existing ground subsidence areas at the study site. Seven major factors causing ground subsidence were extracted from the probability analysis of the existing ground subsidence area: I) depth of drift from the mining tunnel map and distance from drift; 2) slope gradient, calculated from the topographical map; 3) groundwater level and permeability, from borehole data; 4) geology from the geological map; and 5) land use from the land use map. The frequency ratio and logistic regression models were applied to determine each factor's rating and the ratings were overlain for ground subsidence hazard mapping. The ground subsidence hazard map was then verified and compared with existing subsidence areas. The verification results showed that the logistic regression model (accuracy of 96.75%) is better in prediction than the frequency ratio model (accuracy of 95.64%). The verification results showed sufficient agreement between the hazard map and the existing data on ground subsidence area. Analysis of ground subsidence with the frequency ratio and logistic regression models suggests that quantitative analysis of ground subsidence near AUCMs is possible.

Lee J.,National Academy of Agricultural Science | Cho J.,Gwangju Institute of Science and Technology | Kim S.H.,National Institute of Environmental Research NIER | Kim S.D.,Gwangju Institute of Science and Technology
Ecotoxicology and Environmental Safety | Year: 2011

The aims of this study were to determine the sorption coefficient (LogKDOC) of 17Β-estradiol (E2), according to the size and composition of dissolved organic matter (DOM) isolated from wastewater effluent using a fluorescence quenching (FQ) method, and to measure the estrogenic changes due to the extent of E2 sorption onto effluent DOM (EfOM) by using an E-screen bioassay. The highest logKDOC of E2 for a DOM size fraction less than 0.2μm was observed by 4.87±1.87Lkg-1 DOC, and its estrogenicity was the lowest among all the size fractions at 1.2ng-EEQL-1. However, E2 estrogenicity for a DOM size fraction less than 5kDa was as high as that for the positive control due to the absence of fulvic acid- and protein-like DOM to bind with E2. The estrogenic activity for the hydrophobic fraction bound with E2 was significantly reduced to 1.6ng-EEQL-1, while that for the hydrophilic fraction having no binding with E2 was 2.6ng-EEQL-1, which was similar to that of the positive control (i.e., 2.8ng-EEQL-1). The results support a conclusion that the change in estrogenicity was due to the strong sorption affinity of E2 onto DOM. © 2011 Elsevier Inc.

Jung J.H.,Korea Institute of Science and Technology | Jung J.H.,California Institute of Technology | Lee J.E.,National Institute of Environmental Research NIER
Journal of Aerosol Science | Year: 2013

This study describes the real-time fluorescence characteristics of bacterial bioaerosols (Escherichia coli and Bacillus subtilis) thermally inactivated to produce various degrees of cellular culturability. Bacterial bioaerosols were exposed to various temperatures for very short times in a thermal electric tube furnace and then passed into an aerosol fluorescence measurement system that measured the ultraviolet (UV) light-induced fluorescence intensity of airborne particles in real time. The fluorescence of particles in the optical sensing zone was continuously measured with two photomultiplier tubes (PMTs) equipped with optical filters to detect radiation in the UV and visible (Vis) bands. The results showed that both UV- and Vis-fluorescence intensities decreased with increasing deactivation temperature. Also, the ratio of UV- to Vis-fluorescence decreased with increasing temperature for each bacterial bioaerosol. Under the same experimental conditions, we found that the airborne aromatic amino acids (L-tryptophan and L-tyrosine) and ovalbumin particles showed similar reduction trends in their fluorescence characteristics, compared with the test bacterial bioaerosols. These results provide basic information on the feasibility of intrinsic fluorescence measurements for real-time characterization of biological particles. © 2013 Elsevier Ltd.

Kim C.-H.,Pusan National University | Park S.-Y.,Pusan National University | Kim Y.-J.,Pusan National University | Chang L.-S.,National Institute of Environmental Research NIER | And 3 more authors.
Atmospheric Environment | Year: 2012

Several indicators of the long-range transport potential of particulate matters have been proposed. These indicators can be used in the interpretation of the long-range transport process over northeast Asia. In order to characterize the indicators of long-range transport potential for days during which the concentration of particulate matter is high, we first classified these days during which PM 10 concentration was high into two extreme synoptic cases: long-range transport (LRT) case, and local emission with stagnation (LES) case. The classification employed here was on the basis of semi-empirical approach by employing the synoptic meteorological variables including relative vorticity, vorticity advection, and geostrophic wind speed/direction at a geopotential level of over 850 hPa. Simulation results of the two cases using the MM5-CMAQ modeling system were contrasted to determine suitable indicators of LRT potential. The results showed that the most effective indicator is the ratio of aromatic organic compounds to NO x, with correlation coefficients of 0.70 for toluene/NO x, and 0.72 for xylene/NO x. The ratios of N-containing species such as NO x (or NO y) to CO were the next best alternative indicators, with correlation coefficients of 0.53-0.62. The sulfur conversion ratios such as SO 4 2-/(SO 2 + SO 4 2-) and SO 4 2-/SO 2 suggested good indicators for high sulfate condition (i.e., SO 4 2- > 10 μg m -3). However, carbon aerosol ratio OC/EC did not show clearly separated regression lines distinguishing the LRT and LES cases, implying that ratios of both sulfur conversion in less polluted atmosphere and carbon aerosol should be considered carefully using them with confidence about their indication of the LRT potential over northeast Asia. © 2011 Elsevier Ltd.

Kim K.T.,Gwangju Institute of Science and Technology | Klaine S.J.,Clemson University | Cho J.,Gwangju Institute of Science and Technology | Kim S.-H.,National Institute of Environmental Research NIER | Kim S.D.,Gwangju Institute of Science and Technology
Science of the Total Environment | Year: 2010

Size is one of important factors determining titanium dioxide nanoparticle (TiO2 NP) toxicity since penetration is eased with decreasing particle size and bioavailability is increased. The effect of particle size on oxidative stress against titanium dioxide nanoparticle (TiO2 NP) exposure to Daphnia magna was investigated with both acute and chronic toxicity tests. Experiments on biochemical responses, repeatedly performed after size fractionation of the NPs using filtration, focused on the activities of four antioxidant enzymes: catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPX), and glutathione-S-transferase (GST). In the chronic bioassay, the mortality was significantly increased at TiO2 NP concentrations of 5 and 10 mg/L; however, no reduction of the reproduction ability was observed. Biochemical measurements showed that TiO2 NP exposure significantly increased the antioxidant enzyme activities in D. magna. CAT, GPX and GST, but not SOD, showed a concentration-dependent increase. In terms of size fraction, particles ranging from 400 to 800 nm exhibited an increase of antioxidant enzyme activities in GST and GPX. These biochemical level observations suggested that TiO2 NP toxicity was mediated by reactive oxygen species (ROS) generation via oxidative stress in D. magna. The increased mortality at the concentration of 5 mg/L in the chronic bioassay was attributed to accumulated TiO2 NPs in the intestine of D. magna, which might induce effects such as oxidative stress relating to the induction of antioxidant enzymes. © 2010 Elsevier B.V. All rights reserved.

Kim M.,National Institute of Environmental Research NIER | Wolf C.,Social Impact Assessment Center
Impact Assessment and Project Appraisal | Year: 2014

The impact assessment (IA) we want seeks to balance the 'productive harmony' between people and nature by enhancing the quality of life while maintaining the integrity of natural systems. Its focus centers on 'sustainable futures' as the goal of integrated IA. © 2014 © 2014 IAIA.

Kim C.-G.,Korea Research Institute of Bioscience and Biotechnology | Kil J.,National Institute of Environmental Research NIER
Biological Invasions | Year: 2016

The Korean Peninsula has been divided into the countries of North and South Korea since 1948. This adoption of different political and socio-economic regimes has significantly changed economic activity and international exchange by those nations, thus affecting the introduction of alien plants. Our study objective was to provide a comprehensive, up-to-date inventory of the alien flora on the Korean Peninsula and to analyse how the partitioning between North and South Korea has influenced the numbers and status of those alien plants. We identified pre-1876 aliens that were brought to the Korean Peninsula before 1876, when Korea opened up to foreign countries, and also determined the post-1876 aliens that were introduced after 1876. Plants in the latter group were further classified into those that arrived before the outbreak of the Korean War in 1950 (1876–1950 aliens) and those introduced since then (post-1950 aliens). We investigated the regions of origin, family compositions, and invasion status of those alien taxa. In total, 504 alien taxa were identified, with 102 taxa being pre-1876 and 117 being 1876–1950 aliens. After the Korean War, the number of alien plants in South Korea more than doubled (276 taxa), whereas the number reported for North Korea was considerably lower (33 taxa). This might be due to enhanced economic activity and a larger human population in South Korea. Climatic differences as well as variations in the recording intensity for alien flora between North and South Korea may also have contributed to the large contrast in numbers of new alien species recorded during the last decades. Coordinated measures between the two nations are necessary if the spread of invasive alien plants onto the Korean Peninsula is to be reduced. © 2016 Springer International Publishing Switzerland

Loading National Institute of Environmental Research NIER collaborators
Loading National Institute of Environmental Research NIER collaborators