Seyferth 시약인 phenyl(tribromomethyl)mercury 및 diazomethane의 식품보존제인 dehydroacetic acid 및 coumarin과의 발암성과 그 반응기작을 분자 구조적 관점에서 알아보기 위하여 UV/vis 조건과 laser flash photolysis 시켰을 때의 결과는 다음과 같다. 1. Diazomethane과 phenyl(tribromomethyl) mercury와 dehydroacetic acid와 diazomethane과의 반응은 광화학적 분해 반응에서 생산된 : CBr_2 와 :CH_2 카르벤 중간체의 이탈기 효과에 따라 발암성이 크게 나타났다. 2. Laser flash photolysis 상에서 반응시켰을 때 식품보존제의 발암성이 UV/vis 상에서의 photolysis때보다 크게 나타났다.

The photochemical characteristics were analyzed in the context of sowing time and different levels of fertilized nitrogen during the maize (Zea mays L.) growth. When maize was early sawn, the fluorescence parameters related with electrontransport, in photosystem II (PSII) and PSI, were effectively enhanced with the higher level of fertilized nitrogen. Highest values were observed in maize leaves grown in double Nfertilized plot. The photochemical parameters were declined in the progress of growth stage. In early growth stage, the fluorescence parameters were highest, and then reduced to about half of the parameters related with electron transport on PSII and PSI at middle and late growth stages. In 1/2 N plot, the photochemical energy dissipation was measured to 13% in term of active reaction center per absorbed photon resulting in decrease in performance index and driving force of electron. This decrease induced to lower the photochemical effectiveness. In 2 N plots, the electron transport flux from QA to QB per cross section and the number of active PSII RCs per cross section were considerably enhanced. It was clearly indicated that the connectivity between photosynthetic PSII and PSI, i.e. electron transport, was far effective.

많은 미생물들이 수용성 망간이온(Mn2+)을 불용성인 산화망간(Mn4+) 광물로 산화 침전시키는데, 이와 같은 생물학적 산화반응은 비생물학적 산화반응보다 훨씬 빠르게 일어난다. 이처럼 미생물에 의해 생성된 바이오 산화망간 광물은 표면의 강한 흡착성과 산화환원 반응을 통해 생지구화학 순환과 환경오염물질의 생물흡수도에 큰 역할을 한다. 본 논평은 양자역학의 밀도범함수 이론에 바탕을 둔 전산모사를 이용하여 산화망간 광물 표면의 독성금속 흡착의 자세한 기작과 망간원자 빈자리의 광화학적 역할을 새롭게 밝힌 최근 연구결과를 소개한다.

In predicting oxidants concentration, the most important fact is to select a suitable photochemical reaction mechanism. Sensitivity analysis of O3 and other important photochemical oxidants concentrations was conducted by using CBM-IV model. The predicted oxidants concentration was considerably related with the initial concentration of formaldehyde, [NO2]/[NO],NOx, RH and RCHO. As the initial concentration of formaldehyde increased, concentration of NO2 increased. O3 concentration was proportional to the [NO2]/[NO] ratio. When the initial concentrations of RH and RCHO were high, photochemical reaction was more reactive, including more rapid conversion of NO to NO2 and increased oxidants. Also, the sensitivities of ozone formation to rate constants, Kl,K2andK3 in the NO2 photolysis were studied.

The number of cases exceeding environmental standards of atmospheric ozone in the major cities in Korea has steadily increased during the past decades. In order to understand and analyze the atmospheric reactions in the atmosphere, especially the secondary photochemical reactions, smog chambers studies have been performed very actively by many research groups worldwide. However, these studies have focused on the mechanism of photochemical reactions in high concentration conditions, not at the ambient levels. Therefore, in-depth studies in these conditions are essentially needed to realize exact mechanism in the atmosphere near the earth surface, especially at Korean atmospheric conditions. In this experiment, the mechanism of photochemical smog was examined through a comparative experiment of smog chambers under sun light and black light conditions. The results of our study indicated that concentrations of ozone, aldehyde, and PAN increased as the radiation of light source increases. Photochemical reaction patterns can be considered quite similar for both black light and sun light experiments. Based on our experiments using toluene as a reactant which is present at significant high levels in ambient air relative to other VOCs, it was found that toluene could contribute notably to oxidize NO to NO2, this reaction can eventually generate some other photochemical oxidants such as ozone, aldehyde, and PAN. The results of simulation and experiments generally showed a good agreement quite well except for the case of O3. The restriction of oxidization of NO to NO2 seems to cause this difference, which is mainly from the reaction of peroxy radical itself and other reactants in the real gas.

The Photodegradation efficient of total organic compounds in the drinking water has been studied using the methods of photocatalytic reaction and laser beam irradation. The results are summarized as follows; 1. The photodegradation efficiency of total organic compounds shows as 50% to 80% as within one hour and after this the efficiency is decreased slowly. 2. The photodegradation efficiency of total organic compounds shows as 65 to 90% within 3.3min. when Nd : YAG beam is irradiated to the water layer. 3. An excellent observation of the organic compound removal efficiency gives revealed in that case of the longest wavelength of 532nm is irradiated among the three kinds of laser beam sources of 532nm, 355nm and 266nm. 4. The organic compound removal efficiency shows high in the case of UV beam irradiation in the thin layer of water. However the efficiency is not depended on the thickness of water layer severely. 5. The removal efficiency of the organic compounds in the direct irradiation shows higher than the indirect irradiation in the case of UV beam, but the efficiency is not depended on the direction of irradiation in the case of Nd : YAG beam irradiation.

The photocatalytic decolorization and photodegradation of wastewater contamininated with dyes such as methyleneblue tetrahydrate(MBT), methyl orange(MO), phenol red(PR) and the mixed dyes have been studied using a batch reactor in the presence of aerotropic and titania. Degussa P25 titanium oxide was used as the photocatalyst and proved to be effective for the dyes-degradation when irradiated with UV-light source emitting the wavelength of 253.7 nm in the presence of air. In addition to removing the color from the wastewater, the photocatalytic reaction simultaneously reduced the COD and optical density which suggests that the dissolved organic compounds have been photooxidized. The reaction rate of disappearance of the dyes were measured as a function of the irradiation times. The photooxidative procedure of the aquatic solution have the first order reaction-kinetics. The rate constants were increased in the order of PR < MBT < <MO < mixing dyes, and all of these dyes have been mostly photodegraded within 240-minutes, when the aquatic sample solution containing 0.5 gL-1-TiO2 powder were irradiated with the UV-light source.