• Journal of Bio-Environment Control
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• v.32 no.4
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• pp.342-352
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• 2023

Ultra-violet (UV) light is one of abiotic stress factors and causes oxidative stress in plants, but a suitable level of UV radiation can be used to enhance the phytochemical content of plants. The accumulation of antioxidant phenolic compounds in UV-exposed plants may vary depending on the conditions of plant (species, cultivar, age, etc.) and UV (wavelength, energy, irradiation period, etc.). To date, however, little research has been conducted on how leaf thickness affects the pattern of phytochemical accumulation. In this study, we conducted an experiment to find out how the antioxidant phenolic content of kale (Brassica oleracea var. acephala) leaves with different thicknesses react to UV-A light. Kale seedlings were grown in a controlled growth chamber for four weeks under the following conditions: 20℃ temperature, 60% relative humidity, 12-hour photoperiod, light source (fluorescent lamp), and photosynthetic photon flux density of 121±10 µmol m^-2 s^-1. The kale plants were then transferred to two chambers with different CO₂ concentrations (382±3.2 and 1,027±11.7 µmol mol^-1), and grown for 10 days. After then, each group of kale plants were subjected to UV-A LED (275+285 nm at peak wavelength) light of 25.4 W m^-2 for 5 days. As a result, when kale plants with thickened leaves from treatment with high CO₂ were exposed to UV-A, they had lower UV sensitivity than thinner leaves. The Fv/Fm (maximum quantum yield on photosystem II) in the leaves of kale exposed to UV-A in a low-concentration CO₂ environment decreased abruptly and significantly immediately after UV treatment, but not in kale leaves exposed to UV-A in a high-concentration CO₂ environment. The accumulation pattern of total phenolic content, antioxidant capacity and individual phenolic compounds varied according to leaf thickness. In conclusion, this experiment suggests that the UV intensity should vary based on the leaf thickness (age etc.) during UV treatment for phytochemical enhancement.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.363-366
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• 2003

본 연구는 membrane bioreactor (MBR)을 질산화 위주로 운영하면서 질소폐수 처리 과정에서 나타나는 MBR의 운전특성 및 처리효율을 검토하고, 아울러 경제적인 질소처리 방법인 아질산화를 유도하기 위한 조건을 탐색하는 것이다. 반응기의 유효부피 8 L, 체류시간을 12시간으로 고정하고 유입폐수 중의 암모니아 농도를 증가시키는 방법으로 암모니아 부하를 $2\;kg/m^3{\cdot}day$까지 증가시켜 보았다. 운전 중반부에 이유를 명확히 알 수 없는 슬러지의 활성 저하 기간을 제외하고는 거의 98% 이상의 질산화 효율을 나타냈으며, 2 kg 이상의 암모니아 부하에서는 효율이 감소하였다. pH 조절, 유입수의 암모니아 농도 및 부하 조절에 의해 MBR 내의 free ammonia (FA) 농도를 변화시켜, FA 저해에 의한 유도한 아질산화는 매우 불안정하게 이루어졌다. 반면에, 공기 공급량을 변화시켜 반응기 내의 DO를 낮추는 방법으로 유도한 아질산 축적은 안정적인 경향을 보여 MBR에서 적절한 운전전략으로 판단된다.

• Journal of the Korean Society for Marine Environment & Energy
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• v.13 no.4
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• pp.288-295
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• 2010

Metal exposure experiments using polychaete (Perinereis nuntia) as a bio-indicator of trace metals contamination were conducted to evaluate the bioaccumulation and the biomarkers responses such as metallothionein-like protein (MTLPs) and glutathione S-transferase (GST) which was simultaneously exposed to Cadmium (Cd) and Copper (Cu). Cu and Cd concentrations in polychaete were enhanced with increasing exposure time and their concentrations of aqueous medium. Initial accumulation of Cd was higher than that of Cu. Our results showed that the bioaccumulation of Cu and Cd were prohibited, especially at higher Cu levels, suggesting the different cellular uptake mechanisms when Cu and Cd are co-exist. Net accumulation rate of Cu was declined with exposure time but it did not show any significant change for Cd. Although the highest MTLPs concentration was observed at 6 hr of exposure time, it did not show any significant change related to exposure times and metals concentrations. An increase of GST activity tended to increase as a function of exposure time and metals concentrations. And GST activities in P. nuntia have similar tendency with bioconcentration factors in high concentration of Cu (treatment group IV) at post 24 h of exposure. Our results provide new information of the bioaccumulation and biomarker responses to understand the effects of co-existing contaminants (Cu and Cd) using polychaete. Further studies are required to elucidate the bioaccumulation and biomarkers responses for various contaminants.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.1
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• pp.53-60
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• 2000

The effects of ammonia loading on nitrification, especially on nitrite build-up, in an activated carbon fluidized bed reactor were investigated by increasing the ammonia loading rate stepwise from 0.1 to $7.5kg\;NH_3-N/m^3{\cdot}day$. Although effluent nitrite concentration and nitrification efficiency fluctuated at the loading rates above $1.8kg\;NH_3-N/m^3{\cdot}day$, an average nitrification efficiency of 90% was achieved. Nitrite build-up began at an ammonia loading rate of $l.8kg\;NH_3-N/m^3{\cdot}day$, at which the free ammonia concentration was estimated to be above 1 mg/L. During the nitrite build-up, the ratio of influent $NH_3-N$ concentration to the DO concentration of the reactor liquor and the ratio of effluent $NH_3-N$ concentration to the DO concentration of the reactor liquor was measured to be above 100 and 2, respectively. Considering the advantages of nitritation/denitrification, a fluidized bed reactor could be an effective means for biological nitrification of wastewaters with high ammonia concentration.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.11
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• pp.947-956
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• 2009

Residual petroleum hydrocarbons after an oil spill may accumulate in the marine benthic ecosystem due to their high hydrophobicity. A lot of monitoring data are required for the estimation of ecosystem exposure to residual petrochemicals in an ecological risk assessment in the affected region. To save time and cost, the environmental exposure to them in the affected ecosystem can also be assessed using a simple food-web bioaccumulation model. In this study, we evaluated residual concentrations of four selected polycyclic aromatic hydrocarbons (phenanthrene, anthracene, pyrene, and benzo[a]pyrene) in a hypothetic benthic ecosystem composed of six species under two exposure scenarios. Body-residue concentration ranged 5~250 mg/kg body depending on trophic positions in an extreme scenario in which the aqueous concentrations of PAHs were assumed to be one-tenth of their aqueous solubility. In addition, bioconcentration factors (BCFs) and bioaccumulation factors (BAFs) were evaluated for model species. The logarithm of bioconcentration factor (log BCF) linearly increased with increasing the logarithm of 1-octanol-water partition coefficient (log $K_{OW}$) until log $K_{OW}$ of 7.0, followed by a gradual decrease with further increase in log $K_{OW}$ without metabolic degradation. Biomagnification became significant when log $K_{OW}$ of a pollutant exceeded 5.0 in the model ecosystem, indicating that investigation of food-web structure should be critical to predict biomagnifications in the affected ecosystem because log $K_{OW}$ values of many petrochemicals are higher than 5.0. Although further research is required for better site-specific evaluation of exposure, the model simulation can be used to estimate the level of the ecosystem exposure to residual oil contaminants at the screening level.

• The Korean Journal of Zoology
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• v.37 no.2
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• pp.222-231
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• 1994

밤바구미 유충기의 whole body로부터 cyclic AMP(CAMP)를 추출하여 농도 변화를 측정하였고 cyclic AMP-dependent protein kinase(PKA)를 부분 정제하여 활성도 변화를 조사하여 CAMP 농도와 PKA 활성도와의 소장관계를 비교하였다 CAMP 농도와 PKA 활성도는 HPLC와 liquid scintillation counter를 이용하여 측정하였다 CAMP 농도는 밤바구미 유충에서 월동전에 0.57 UMlg로 가장 높았고, 월동중에 0. 14 UMIS로 감소하였다가 월동후에 0.29 UMlg로 증가하였다 또한 PKA 활성도는 월동전에 2.56unit/mg로 가장 높았으며, 월동중에 0.62 unit/mg로 감소하다가 월동후에 07 unit/mg로 다시 증가하여 CAMP 농도 변화와 유사한 경향을 나타내었다. 이는 월동전에 휴면에 대비하여 최대의 취식으로 지방체 축적이 가장 많았고, 월동중에는 지방체의 소비가 증대되.기 때문에 감소하였다가, 월동후 휴면 종결과 유충-번데기 탈피를 준비하기 위해 'CAMP 농도와 PKA 활성도는 다시 증가하였다.

• KSBB Journal
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• v.19 no.4
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• pp.327-330
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• 2004

An inducible expression system of poly[(R)-3-hydroxybutyrate] (PHB) depolymerization was established in metabolically engineered Escherichia coli with the PHB biosynthesis genes. The Ralstonia eutropha PHB depolymerase gene was cloned in a vector system containing the PHB biosynthesis genes and expressed under inducible promoter. Recombinant E. coli harboring the PHB biosynthesis genes and depolymerase gene was first cultured for the accumulation of PHB, and then the depolymerase was expressed resulting in the degradation of accumulated PHB into (R)-3-hydroxybutyric acid (R3HB). R3HB could be produced with the concentration of 7.6 g/L in flask culture. Two different PHB biosynthesis genes from Alcaligenes latus and R. eutropha were compared for the production of R3HB. This strategy can be used for the production of enantiomerically pure (R)-hydroxycarboxylic acids with high concentration.

• Korean Journal of Environment and Ecology
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• v.36 no.6
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• pp.566-574
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• 2022

Heavy metals are one of the dangerous pollutants that threaten urban biodiversity due to their accumulation over a long period without being decomposed in vivo. Accordingly, there is a need for biological monitoring to compare accumulation concentrations in living organisms according to the degree of heavy metal exposure to evaluate heavy metal contamination in the air in urban areas. This study aims to examine the possibility of using nesting materials as heavy metal monitoring samples and determine the effects of heavy metals on Paridae. We installed 54 artificial nest boxes in the research areas that included campus green spaces (14), urban forests (11), and urban parks (29) on a university campus in Cheonan City, Chungcheongnam Province. The birds' use rate of artificial nest boxes was 11/14 (78.57%) in campus green spaces, 8/11 (72.72%) in urban forests, and 6/29 (20.68%) in urban parks. Moss materials were collected from collected nests, and the heavy metal accumulation characteristics of each type of urban green space and the effects of heavy metals on the success of fledging of Paridae were compared through heavy metal analysis. The analysis showed that the average concentrations of zinc and lead were 228.08±209.62 ㎍/dry g and 17.67 ± 6.72 ㎍/dry g, respectively. There was no significant difference in zinc concentration for each type of urban green space (Kruskal-Wallis test, p-value=0.28), but lead concentration showed a significant difference (Kruskal-Wallis test, p<0.05^*). Of the 21 Paridae, nests analyzed for heavy metals, fledging of birds was observed in 11 nests (52.38%). Fledging of birds observed in each urban green space type was 7 campus green spaces (77.78%), 6 in urban forests (85.71%), and 1 in urban park (20%), mainly in urban forests and green spaces on campus. Heavy metal concentrations were compared to check the effect of heavy metal accumulation on the successful fledging of Paridae, but there was no statistically significant difference (Zn: W=44, p-value=0.74, Pb: t=0.64676, df =7.2422, p-value=0.54). This study is a basic study using the nesting materials of Paridae as heavy metal monitoring samples, and it is determined that it can be used as basic data for non-invasive biological monitoring.

• Applied Biological Chemistry
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• v.39 no.4
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• pp.287-292
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• 1996

The present study was carried out to investigate the difference of absorption and translocation of Ni by radish grown for 45 days under factors such as the levels of Ni in soil, soil pH, competitive metal interactions, covering with soil, organic matter and lime. Germination rate of radish in soil treated by Ni 150 mg/kg was 40%. As soil pH was increased, the contents of Ni translocated to radish showed the negative correlation$(shoot=-0.965^{**},\;root= -0.837^{*})$. The Ni content in shoot and root of radish grown under 50 mg/kg Ni treated soil were slowly decreased with iron levels increased. However Ni content in shoot and root of radish grown under 50 mg/kg Ni treated soil showed increasing trend with the increasing the zinc levels. As covering with soil, organic matter and lime were treated, Ni contents of shoot and root in radishes were in the decreasing order of organic matter>covering with soil>lime.

• Economic and Environmental Geology
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• v.37 no.3
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• pp.335-345
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• 2004

Total and extractable contents of heavy metals were measured in sediment and seafood from Bukhang and Boggil-ri tidal flats along the Mokpo coastal area, south-western part of Korean peninsular in order to assess the degree of metal pollution, metal bioavailability and metal hioaccumulation. The metal concentrations, except Pb were found to be greater than the background concentrations of sediments indicating the progress of cumulative contamination by anthropogenic origin of metals. The order of extractable metal concentrations in sediments were Mn(32-53 mg/kg)＞Zn(14-42 mg/tg)＞Cu(2.5-17.0 mg/kg)＞Pb(2.4-6.8 mg/kg)＞Cd(0.5-0.7 mg/kg). However, the amount of metals associated with extractable fraction of sediments were significantly high in Bukhang relative to Boggil-ri. Significant bioaccumulation of all metals, except Pb were observed in seaweed and benthos. The order of bioaccumulation of metals were: in concentration; all biota commonly, Mn(129-374 mg/kg)＞Zn(19-106 mg/kg)＞Cu(6-87 mg/kg)＞Cd(4.6-7.6 mg/kg)＞Pb(0.2-3.7 mg/kg), in BCF; Enteromorpha, Cd＞Mn＞Cu＞Zn＞Pb, Ilyoplax deschampsi, Cu＞Cd＞Mn＞Zn＞Pb, Urechis unicinctus, Cd＞Zn＞Mn＞Cu＞Pb. Some metal concentrations of Enteromorpha, especially Cu, Zn, weakly Pb in bukhang, Mn, Cd in boggili-ri, were correlate well with concentrations in sediment, indicating relatively more contaminated by the anthropogenic origin of metals in each tidal flat. The results clearly indicate that the seafood of bukhang, even of Boggili-ri known as clean area, are contaminated with metals.