Keunje Yoo

Molecular approaches for the detection and monitoring of microbial communities in bioaerosols: A review.

Bioaerosols significantly affect atmospheric processes while they undergo long-range vertical and horizontal transport and influence atmospheric chemistry and physics and climate change. Accumulating evidence suggests that exposure to bioaerosols may cause adverse health effects, including severe disease. Studies of bioaerosols have primarily focused on their chemical composition and largely neglected their biological composition and the negative effects of biological composition on ecosystems and human health. Here, current molecular methods for the identification, quantification, and distribution of bioaerosol agents are reviewed. Modern developments in environmental microbiology technology would be favorable in elucidation of microbial temporal and spatial distribution in the atmosphere at high resolution. In addition, these provide additional supports for growing evidence that microbial diversity or composition in the bioaerosol is an indispensable environmental aspect linking with public health.

Comparison of fatty acid analysis methods for assessing biorefinery applicability of wastewater cultivated microalgae

In this study, we compared the performances of four different gas chromatography (GC) based microalgal fatty acid analysis methods that are typically applied to biorefinery research using wastewater-adapted microalgae. Compared with the HP-5-type non-polar column, WAX-type polar columns exhibited excellent abilities to quantitatively separate C(16)-C(18) polyunsaturated fatty acids (PUFAs) from selected wastewater-adapted microalgae (Chlorella vulgaris, Ankistrodesmus gracilis and Scenedesmus quadricauda) isolates. GC-mass spectroscopy (MS) using the WAX-type polar column provided the strongest detection sensitivity among the tested methods by lowest detection limit, and GC-flame ionized detector (FID) with the same polar column exhibited nearly consistent results to GC-MS analysis. Our statistical comparison of microalgal fatty acid composition profiles generated using various GC methods, microalgal resources and culture media (wastewater, BG11 and nitrogen limitation) suggested that an appropriate GC method and algal resource choice are more important than the optimization of culture conditions to evaluate the applicability of microalgal biorefinery using wastewater resources.

Using GA-Ridge regression to select hydro-geological parameters influencing groundwater pollution vulnerability.

For groundwater conservation and management, it is important to accurately assess groundwater pollution vulnerability. This study proposed an integrated model using ridge regression and a genetic algorithm (GA) to effectively select the major hydro-geological parameters influencing groundwater pollution vulnerability in an aquifer. The GA-Ridge regression method determined that depth to water, net recharge, topography, and the impact of vadose zone media were the hydro-geological parameters that influenced trichloroethene pollution vulnerability in a Korean aquifer. When using these selected hydro-geological parameters, the accuracy was improved for various statistical nonlinear and artificial intelligence (AI) techniques, such as multinomial logistic regression, decision trees, artificial neural networks, and case-based reasoning. These results provide a proof of concept that the GA-Ridge regression is effective at determining influential hydro-geological parameters for the pollution vulnerability of an aquifer, and in turn, improves the AI performance in assessing groundwater pollution vulnerability.

Decision-Tree-based data mining and rule induction for predicting and mapping soil bacterial diversity

Soilmicrobial ecology plays a significant role in global ecosystems. Nevertheless, methods of model prediction and mapping have yet to be established for soil microbial ecology. The present study was undertaken to develop an artificial-intelligence- and geographical information system (GIS)-integrated framework for predicting and mapping soil bacterial diversity using pre-existing environmental geospatial database information, and to further evaluate the applicability of soil bacterial diversity mapping for planning construction of eco-friendly roads. Using a stratified random sampling, soil bacterial diversity was measured in 196 soil samples in a forest area where construction of an eco-friendly road was planned. Model accuracy, coherence analyses, and tree analysis were systematically performed, and four-class discretized decision tree (DT) with ordinary pair-wise partitioning (OPP) was selected as the optimal model among tested five DT model variants. GIS-based simulations of the optimal DT model with varying weights assigned to soil ecological quality showed that the inclusion of soil ecology in environmental components, which are considered in environmental impact assessment, significantly affects the spatial distributions of overall environmental quality values as well as the determination of an environmentally optimized road route. This work suggests a guideline to use systematic accuracy, coherence, and tree analyses in selecting an optimal DT model from multiple candidate model variants, and demonstrates the applicability of the OPP-improved DT integrated with GIS in rule induction for mapping bacterial diversity. These findings also provide implication on the significance of soil microbial ecology in environmental impact assessment and eco-friendly construction planning.

Improved TNT detoxification by starch addition in a nitrogen-fixing Methylophilus-dominant aerobic microbial consortium

In this study, a novel aerobic microbial consortium for the complete detoxification of 2,4,6-trinitrotoluene (TNT) was developed using starch as a slow-releasing carbon source under nitrogen-fixing conditions. Aerobic TNT biodegradation coupled with microbial growth was effectively stimulated by the co-addition of starch and TNT under nitrogen-fixing conditions. The addition of starch with TNT led to TNT mineralization via ring cleavage without accumulation of any toxic by-products, indicating improved TNT detoxification by the co-addition of starch and TNT. Pyrosequencing targeting the bacterial 16S rRNA gene suggested that Methylophilus and Pseudoxanthomonas population were significantly stimulated by the co-addition of starch and TNT and that the Methylophilus population became predominant in the consortium. Together with our previous study regarding starch-stimulated RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) degradation (Khan et al., J. Hazard. Mater. 287 (2015) 243-251), this work suggests that the co-addition of starch with a target explosive is an effective way to stimulate aerobic explosive degradation under nitrogen-fixing conditions for enhancing explosive detoxification.

State of the Art on Legislation for Subsurface Environment Management in Korea

ABSTRACT Many legislations have been implemented in order to manage the subsurface environment in Korea. However, there wasno control tools for managing subsurface environment so effectively. In this study, many laws and regulations wereanalyzed for extracting Korean subsurface environment management plan. Korean government need to 1) establish thebasic paradigm for building the subsurface space, 2) establish the clear subsurface environment management systems, 3)establish the regulations related with subsurface space compensation, 4) prepare the human health and ecosystem relatedlegislations.Key words : Subsurface environment, Laws, Regulations, Policy implications 1. 서론 2014년부터 2015년까지 연속하여 발생한 땅꺼짐 현상,포트홀 등의 지반 침하 현상으로 인해 국민들의 지중 환경 안전 관련 분야에 대한 관심이 매우 높아졌다. 2015년현재 지반 침하 관련 사고가 발생하는 경우 정부에서는전문가로 구성된 비상대책 위원회를 구성하여 사고의 원인을 조사하고 피해가 확산되지 않도록 조치하고 있다.하지만 지반 침하의 원인이 매우 다양하며 관계 법령이산재되어 있는 등의 제도적 기반 부족으로 인해 전문가의의견이 제대로 수렴되기 어려운 실정이다.또한 이해 관계자 및 책임 소재자에 따라 원인 규명에대한 접근 방식이 달라 원인 규명 자체에도 무척 긴 기간이 소요되고 있다.Lee(2014a)에 의해 크게 네 가지 행위가 지반 침하에주된 영향을 미칠 수 있다고 보고되었다. 첫 번째는 건설시공에 의한 지반 침하 현상이다. 인천 지하철공사 현장인근, 경기도 성남시 신분당선 건설 현장 인근에서 발생한 지반 관련 사고와 연관되어 있다. 두 번째는 광산 활동으로 인한 지반의 붕괴이다. 광산활동을 위해 지반 내 발파작업, 안전 수칙을 위반한 현장운영 등으로 지반이 심각하게 훼손된 경우 빈 공간이 압력을 이겨내지 못하여 지반 침하 현상이 발생할 수 있다.세 번째와 네 번째 지반 침하의 주요 원인은 우수 및지하수에 의한 지반 용해와 지하수위의 저하를 꼽을 수있다. 2015년 3월 강원도 삼척 소재 한 석회석 광산에서는 지반 침하가 심하게 진행되어 보도된 사례가 있다. 석회석 지질에 대한 지반 침하는 지하수의 작용으로 인한자연스러운 현상으로 알려져 있다. 또한 2014년 송파구의석촌 호수 수위저하가 땅꺼짐 현상과 관련이 있다고 보도된 바 있다.이와 같이 지반 침하 현상을 일으키는 다양한 원인 중도심지에서 발생하는 땅꺼짐 현상의 발생원인 1위는 ‘도심지 지반 굴착공사’가 선정되었다. 도심지 기반 굴착공사는 지반 침하의 일차적인 피해 이외에도 수도, 가스, 전력 시설의 파괴를 수반할 수 있기 때문에 더욱 위험한

A Study on the Introduction of Pre-management System to Prevent Soil Contamination by Chemical Accident

Although a number of chemical accidents have been occurred in South Korea, the effective prevention act for soil contamination has not been established so far. To effectively protect soil contamination from chemical accidents, decision support laws and regulations are absolutely essential. Regarding this situation, this study was aimed at diagnosing problems in current chemical safety management and prevention and response system against chemical accidents through analyzing the domestic and foreign causes of chemical accidents and the accident response procedures and finally suggesting policy measures for solving those problems. In order to clarify management of soil contamination by chemical accident, this study suggests the establishment of chemical accident preparedness, response, and making of local chemical management law and policy. This law needs to be supported by a clear management framework to guide government officials and all other stakeholders in the management of soil contamination by chemical accident.