In this study, the spatial and temporal distribution of odorants in ambient air was investigated at three measurement points in a University campus in Seoul city during a 15 day study period. The concentrations of 12 target analytes designated as malodor compounds by KMOE were measured through time. The highest mean concentration (in ppb unit) was found from NH₃(25.3) followed by styrene (0.51) ＞ acetaldehyde (0.13) ＞ H₂S, propionaldehyde (0.07) ＞ butyraldehyde, isovaleraldehyde, and valeraldehyde (0.06) ＞ DMDS (0.04) ＞ TMA (0.03) ＞ CH₃SH and DMS (0.01). Comparison of odorant data showed fairly strong distinctions across diurnal period, while differences in concentration levels were not clear enough between different sampling locations. The results of correlation analysis showed that the concentrations of DMS and NH₃ were strongly correlated with relative humidity. In addition, most of reduced sulfur compounds (RSC) exhibited strong correlations with each other. When the odorant concentrations were converted into odor intensity, the values were typically found below the odor degree of 1. The odor intensity, if assessed by the maximum values of each compound, were generally in between 1~2 odor degree level (e.g., H₂S, CH₃SH, DMDS, acetaldehyde, and TMA). The results of this study thus show that most odorant species occurred below the threshold value at clean space like a University campus. Hence, more efforts are desirable toward the development of the analytical technique at various concentration levels.

In this study, the removal efficiency of 24 odorous compounds was measured in diverse control process units of 7 individual chemical companies located in Ban-Wall & Shi-Wha Industrial Complex in Gyeonggi-do, Korea from March to August, 2007. To quantify the removal efficiency rates of major odorous compounds, we collected odor samples from the inside process and both the front and rear side of 7 control process units. As the results of this study, it was shown that toluene, ammonia, trimethylamine (TMA) and acetaldehyde were dominant odorous compounds in the inside process. In addition, VOCs, TMA and acetaldehyde were also detected at higher concentrations in the stacks and 10 (toluene, acetone, ethyl benzene, xylene etc.) out of 24 index compounds were found to have negative removal efficiencies. According to the removal efficiency evaluation of seven odor control facilities, a company equipped with two connected absorption processes was shown to have positive (＋) removal efficiencies for 16 odor substances and NH₃, TMA, acetaldehyde, the priority odor substances, which meant the proper control system was installed and operated. Hence, to obtain best removal efficiency of odorous pollutant emission, the database on source characteristics and the development of management techniques of diverse control process units are continually needed.

The purpose of this study is to assess the cause of offensive odor incident that took place at Shin-Gil district in Seoul on 17. Nov. 2007. Air samples were collected from both the inside and outside of the accidental sewage site both at the right after and long after the accident and analyzed by GC/MS method. The results of our initial analysis showed that there were 39 compounds with sufficiently detectable quantities (e. g., above ~ 1 ppb). These compounds can be classified into 3 classes of chemical groups which include: Benzene, Indene, and Miscellaneous. It further indicated that compounds with benzene(C₆H₆) ring were the most abundant species followed by several compounds with indene(C₉H₈) structure. Based on our analysis, we conclude that the release of industrial solvents with indene resin contributed most significantly to the observed malodor incident.

Research trend and basic knowledge on the biological degradation of PCE (tetrachloroethylene) were reviewed. At first, anaerobic PCE degradation pathway was introduced, and microorganisms related with biological PCE dechlorination under both anaerobic and aerobic conditions were shown. PCE degradation is readily occurred in anaerobic conditions. Anaerobic PCE degradation was carried out by replacing the strongly combined chloride ion with hydrogen ion. The replacement occurs by electrons from electron donors such as H₂, acetate, lactate, and methanol. The best electron donor for PCE degradation is hydrogen. H₂ produced by the fermentation of carbon source can be used by microorganisms involved in acetogenesis, methanogenesis, sulfidogenesis, dehalorespiration, and iron reduction. These organisms can compete one another in natural ecosystem. Due to the competition, H₂ is sustained at low level. At this low level of H₂, the dechlorination of PCE can be maintained, but is inhibited by highly toxic VC accumulation in anaerobic PCE degradation. Since Dehalococcoides ethenogenes strain 195 can convert PCE into ethene which doesn"t have any toxicity and can further be used as a carbon source, it is very useful for field application. Pseudomonas stutzeri OX1 was able to utilize o-xylene and toluene as a carbon source using toluene-o-xylene monooxygenase for the first time in aerobic coditions. However, it has not further been proven. Based on these basic knowledge of biological PCE degradation, various field applications have been carried out and evaluated. Dehalococcoides related with PCE dechlorination were examined in contaminated sites. In a recent study on a wetland having both anaerobic and aerobic conditions, the effects of soil depth and plant species, and seasonal differences were researched as well as the sequential degradation of PCE. Formate was suggested as an alternative organic compound to efficiently neutralize the PCE degradation product, hydrochloric acid. To improve the PCE biodegradation effectively, the following research directions were proposed: (1) development of aerobically PCE degrading microorganism, (2) development of aerobic/anaerobic hybrid system (3) development of a system capable of maintaining consistent PCE degradation rate regardless of seasonal changes.