• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.241-244
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• 2006

The basic prediction model was constructed to obtain optimal maintenance method for concrete structure under marine environment by exploring the mechanism of mono and combined deterioration in lab. This model was planned to be upgraded with data acquired from several exposure specimens under same environment as structures. The computer program developed to give useful guidance observer would be improved. Several repair materials and repair construction methods applied to exposure specimens will be tested for its performance of prohibit salt attack and freezing & thawing action during experimental period about ten years. All of these data could be available to complete the prediction system. The manager will be able to use the system for optimal maintenance of marine concrete structures.

• 한국수산과학회지
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• 제39권spc1호
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• pp.180-188
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• 2006

We examined the effect of salt marsh vegetation on the benthic environment in macro-tidal flats at Donggeomdo, Ganghwa, on the west coast of Korea. Nine stations were established along a transect across the tidal flats, including salt marsh, and field sampling was conducted monthly from July 1997 to June 1998. During the study period, environmental parameters fluctuated as follows: salinity, 15.0 to 28.2 psu, exposure time, 613 to 702 hr/m, inundation time, 28 to 117 hr/m, sediment organic carbon, 0.71 to 1.34%, nitrogen, 0.07 to 0.16%, sulfur from 0.07 to 0.22%, mean grain size from 6.3 to $6.9{\phi}$, water content from 19.4 to 44.4%, water temperature from 4.4 to $20.4^{\circ}C$ and temperature of the surface sediments, 2.7 to $31.1^{\circ}C$, in total, seven halophyte species were sampled and found to be vertically distributed across the tidal levels. Carer scabrifolia, Suaeda maritima, Limonium tetragonum and Phragmites communis dominated the upper zone of the salt marsh, Juncus haenkei, Triglochin maritimum and P. communis dominated the middle zone, and Suaeda japonica predominated in the lower area. Principal component analysis (PCA) and non-metric multi-dimensional scaling revealed that the zonation of halophytes was related to environmental variables such as salinity and exposure time. The halophyte communities were likely related to the organic content of the surface sediment.

• Corrosion Science and Technology
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• 제7권2호
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• pp.99-111
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• 2008

Copper was exposed unsheltered and sheltered in four humid tropical sites, representing urban, urban-industrial, urban-marine and rural environments. The corrosion rates and the sequence of corrosion product formation are presented and discussed in relation with climatic and atmospheric pollution parameters. Chemical compositions of corrosion products were found to depend on environments and duration of exposure. In all environments, cuprite was the predominating corrosion product that formed first and continuously increased during the exposure. Among the sulphur-containing corrosion products, posnjakite and brochantite were more frequently found and the first formed earlier. Nantokite was the most common chlorine-containing products for most cases, except the high-chloride environment, where atacamite was detected instead. The corrosion rate of copper was well indicated by the colour of patina. The red-purple colour corresponded to the high corrosion rate and the greenish grey colour corresponded to the low corrosion rate. Corrosion rate of sheltered copper in urban-marine environment increased with the exposure time.

• 한국해양환경ㆍ에너지학회지
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• 제13권4호
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• pp.288-295
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• 2010

환경 내 미량금속 오염의 지표생물로 널리 이용되고 있는 갯지렁이의 체내 미량금속 축적 및 생체지표 변화를 연구하기 위하여 구리와 카드뮴에 혼합 노출시킨 Perinereis nuntia의 체내 미량금속의 농도, 금속결합 단백질(metallothioneinlike proteins, MTLPs) 및 항산화효소 중 하나인 글루타치온 S-전이효소(glutathione S-transferase, GST)를 분석하였다. 갯지렁이 체내 미량금속의 농도는 노출 시간과 농도에 따라 증가하였으며, 특히 카드뮴 노출 초기의 축적률과 시간에 따른 증가율이 구리에 비해 높았다. 시간에 따른 미량금속 체내 축적률(net accumulation rate)은 카드뮴의 경우 초기에 높은 값을 보인 후 시간에 따른 증감이 보이지 않았으나, 구리는 노출시간이 증가함에 따라 감소하는 경향을 보였다. 노출시킨 구리의 농도에 따라 두 원소의 축적이 저해되었으며, 이는 원소에 따라 다른 체내 흡수 기작이 있음을 보여주고 있다. 금속결합 단백질은 노출 후 6 시간째 가장 높은 농도를 보였으며 이후 노출시간 증가에 따라 감소하는 경향을 보였으나, 구리의 농도를 $100{\mu}g/L$, $200{\mu}g/L$으로 처리한 실험군의 48 시간째를 제외하고 노출시간과 농도에 따라 유의한 변화를 보이지 않았다. 항산화효소인 글루타치온 S-전이효소의 경우 시간과 농도에 따라 증가하는 경향을 보였으며 갯지렁이 체내 미량금속의 농축 비와 유사하게 높은 구리 농도에서 24 시간 이후 감소하는 경향을 보였다. 본 연구를 통해 구리와 카드뮴이 동시에 영향을 미칠 때 P. nuntia의 체내 미량 금속의 축적과 생체지표의 반응에 대한 정보를 얻을 수 있었으며, 향후 다양한 오염물질에 대한 체내 축적 및 생체지표를 이해하기 위한 연구가 요구된다.

• Corrosion Science and Technology
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• 제13권6호
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• pp.214-223
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• 2014

Interest in the durability assessment and structural performance has increased according to an increase of concrete structures in salt damage environment recent years. Reliable way ensuring the most accelerated corrosion test is a method of performing the rebar corrosion monitoring as exposed directly to the marine test site exposure. However, long-term exposure test has a disadvantage because of a long period of time. Therefore, many studies on reinforced concrete in salt damage environments have been developed as alternatives to replace this. However, accelerated corrosion test is appropriate to evaluate the critical chlorine concentration in the short term, but only accelerated test method, is not easy to get correct answer. Accuracy of correlation acceleration test depends on the period of the degree of exposure environments. Therefore, in this study, depending on the concrete mix material, by the test was performed on the basis of the composite degradation of the salt damage, and investigate the difference of corrosion initiation time of the rebar, and indoor corrosion time of the structure, of the marine environment of the actual environments were inuestigated. The correlation coefficient was derived in the experiment. Long-term exposure test was actually conducted in consideration of the exposure conditions submerged zone, splash zone and tidal zone. The accelerated corrosion tests were carried out by immersion conditions, and by the combined deterioration due to the carbonation and accelerated corrosion due to wet and dry condition.

• 한국해양환경ㆍ에너지학회지
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• 제9권4호
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• pp.187-192
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• 2006

조선소에서 배출되는 처리수, 혼합방류수 및 주변 하천수가 양식 생물에 미치는 생물 독성영향을 알아보기 위해 48시간 급성독성과 DNA 손상을 조사하였다. 조사대상 생물종으로는 조선소 주변에서 양식되고 있는 넙치, 조피볼락, 피조개, 멍게가 사용되었으며, 48 시간 노출 후 치사율을 파악하였고, DNA 손상 정도는 Comet assay을 이용하여 측정되었다. 급성독성 실험 결과, 넙치는 장평천에서 치사가 나타났고(26%), 조피볼락은 혼합방류수 1에서 치사가 나타났다(13%). 멍게는 고현천에서 10%의 치사율을 보였고, 피조개는 어느 시료에서도 치사가 나타나지 않았다. 본 연구에 사용되어진 어떠한 시료에서도 실험생물을 50%까지 치사시키는 독성이 나타나지 않아 $LC_{50}$은 계산될 수 없었다. 넙치는 장평천과 혼합방류수에서 대조구보다 유의하게 높은 DNA 손상을 보여주었고, 조피볼락은 장평천에서 유의하게 높은 DNA손상이 나타났다(p<0.05). 멍게는 세탁폐수에서 유의한 DNA손상이 나타났지만, 피조개에서는 모든 처리구에서 DNA 손상을 보이지 않았다. 치사율과 DNA 손상을 고려하였을 때 조선소의 처리수와 혼합방류수보다는 장평천에서 놀은 생물독성을 보여주는 것으로 나타났다.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2017년도 추계학술발표회
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• pp.236-236
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• 2017

Effluent treated by an NaDCC injection method in Ballast water management system (BWMS) contains reactive chlorine species and disinfection by-products (DBPs). In this study, we conducted whole effluent toxicity (WET) testing and ecological risk assessment (ERA) to investigate its ecotoxicological effects on marine environment. WET testing was carried out for four marine pelagic and freshwater organisms, i.e., diatom Skeletonema costatum, Navicula pellicuosa, chlorophyta Dunaliella tertiolecta, Pseudokirchneriella subcapitata, rotifer Brachionus plicatilis, Brachionus calyciflorus and fish Cyprinodon variegatus, Pimephales promelas. The biological toxicity test revealed that algae was the only biota that showed apparent toxicity to the effluent; it showed no observed effect concentration (NOEC), lowest observable effect concentration (LOEC) and effect concentration of 50% (EC50) values of 25-50%, 50-100% and >100%, respectively, at three water condition, but did not show any significant toxicities on other biota. Meanwhile, chemical analysis revealed that the BWMS effluent contained total residual oxidants (TROs) below $0.03{\mu}g/L$ and a total of 25 DBPs such as bromate, volatile halogenated organic compounds (VOCs), halogenated acetonitriles (HANs), halogenated acetic acids (HAAs), chloropicrin and Isocyanuric acid. Based on ERA, the 25 DBPs were not considered to have persistency, bioaccumulation and toxicity (PBT) properties. The ratio of predicted environmental concentration (PEC) to predicted no effect concentration (PNEC) of the other DBPs did not exceed 1 for General harbor environment. However, four substances (Isocyanuric acid, Tribromomethane, Chloropicrin and Monochloroacetic acid) were exceed 1 for Nearship environment. But observed toxicity in the test water on algal growth inhibition would be mitigated by normal dilution factor of 5 applied for nearship exposure. Thus, our results of WET testing and ERA showed that the BWMS effluent treated by NaDCC injection method would have no adverse impacts on marine environment.

• Fisheries and Aquatic Sciences
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• 제25권3호
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• pp.167-174
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• 2022

Despite the beneficial aspect of fish consumption, bioaccumulation of toxic metals such as arsenic (As) and mercury (Hg) can enhance the health risk for the consumers. Arsenic and Hg concentrations were measured in edible tissue and two targeted organs, namely gill and liver of longtail tuna species (Thunnus tonggol) from Terengganu waters, including Kuala Besut, Kuala Terengganu, Dungun and Kemaman. The concentration of As and Hg were analysed by using inductively coupled plasma- mass spectrometry. The mean concentrations of both elements were significantly different (p < 0.05) among the locations and targeted organs. The hierarchy of As and Hg mean concentrations in muscle samples were Dungun > Kuala Besut > Kemaman > Kuala Terengganu. The mean concentration of As in all samples, including muscle, exceeded the permitted level set by Malaysia Food Act. Estimate Weekly Intake (EWI) was conducted to assess the health risk effect, and 63 kg was used as the average body weight of Malaysian adults. However, the EWI values show that the weekly intake of As and Hg does not exceed the provisional tolerable weekly intake limit suggested by Food and Agricultural Organization for the United Nations and is considered safe to be consumed.

• 생태와환경
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• 제40권4호
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• pp.489-494
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• 2007

Transcriptional modulation of metallothionein (MT) during acute metal exposures (cadmium, copper or zinc) was examined in fry of Hemibarbus mylodon, a threatened fish species in Korean peninsula. Viability of H. mylodon fry was most affected by copper exposure (up to 79% of mortality at 1 ppm for 48 hours) and considerably by cadmium exposure (21 to 54% of mortality). On the other hand, Zn showed the least adverse effect on the viability (0 to 13% of mortality) of this species. Based on the semi-quantitative RT-PCR analysis, the stimulation of MT mRNA in response to metal exposures followed generally in a dose-dependent fashion where cadmium was the most potent inducer for the induction of MT transcripts in fry (up to more than 5-fold) while the lowest response was observed in zinc-exposed group (2-fold at maximum). From the exposure using environmentally realistic doses of cadmium (0 to 0.05 ppm for 24 hours), MT expression at mRNA level was also sensitively modulated toward upregulation up to more than 3-fold as relative to non-exposed control. Results from the present study would be a good basis for understanding the adaptive capacity and stress physiology of this endangered fish species during metal pollution.

• Earthquakes and Structures
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• 제3권5호
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• pp.649-673
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• 2012

Recent studies have highlighted the importance of accounting for aging and deterioration of bridges when estimating their seismic vulnerability. Effects of structural degradation of multiple bridge components, variations in bridge geometry, and comparison of different environmental exposure conditions have traditionally been ignored in the development of seismic fragility curves for aging concrete highway bridges. This study focuses on the degradation of multiple bridge components of a geometrically varying bridge class, as opposed to a single bridge sample, to arrive at time-dependent seismic bridge fragility curves. The effects of different exposure conditions are also explored to assess the impact of severity of the environment on bridge seismic vulnerability. The proposed methodology is demonstrated on a representative class of aging multi-span reinforced concrete girder bridges typical of the Central and Southeastern United States. The results reveal the importance of considering multiple deterioration mechanisms, including the significance of degrading elastomeric bearings along with the corroding reinforced concrete columns, in fragility modeling of aging bridge classes. Additionally, assessment of the relative severity of exposure to marine atmospheric, marine sea-splash and deicing salts, and shows 5%, 9% and 44% reduction, respectively, in the median value bridge fragility for the complete damage state relative to the as-built pristine structure.