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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. Source


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. Source


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. Source


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. Source


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 Source

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