Residence time is defined as the time taken for a material in a system to leave the system. The residence time characteristics in shellfish aquaculture determine the dispersion of excretion from aquaculture farms, along with the supply of food by seawater exchange. In this study, we estimated the spatial distribution of average residence time in the shellfish farming area using a particle tracking model. As a result, a relatively short average residence time of about 20 days or less was calculated in most areas, but an average residence time of more than 40 days was calculated in the inner areas. Relatively long average residence times were calculated along the west coast compared to the east coast, with the longest average residence time of more than 50 days in the northwestern areas. It can be inferred that the disturbance of the benthic ecosystem caused by shellfish farms is likely to be large because of the relatively weak dispersion of excrement from shellfish farms located on the west coast, especially in the northwest region. This distribution of average residence time is important for understanding the potential effects of seawater exchange on the environmental sustainability of shellfish farms, along with the seawater circulation characteristics of Jaran Bay.

본 연구에서는 패류 껍질의 경계조건을 모사한 고연성 시멘트 복합재료의 휨 성능을 평가하였다. 패류 껍질층 경계면 구조를 모방 하여 프리캐스트 형식으로 제조된 패널 사이를 후 타설 HDCC로 충전한 실험체와 PE-mesh를 HDCC층의 경계면에 배치한 실험체 등 2가지 경계면 특성을 고려하여 제작한 4종류 실험체의 휨 성능을 평가하였다. 패류 껍질의 경계조건을 모사한 고연성 시멘트 복합재료의 휨 성능 평가 결과 일반적인 휨 시험체 대비 층상화 단면을 적용한 모든 실험체의 연성이 증가하였다. 특히 PE-mesh를 삽입하여 층상화한 방법이 가장 우수한 연성을 나타내는 것을 확인하였다. 이는 삽입된 PE-mesh가 층을 분리하는 경계면 역할을 하고, PE-mesh 체눈 내의 각주형 HDCC는 층과 층 사이의 부착을 견고히 하는 역할을 하였기 때문이라고 사료된다.

This study was performed to investigate the geochemical and benthic environment of three shellfish farms in Suncheon Bay during the period of September 2014 ~ April 2015. Three sampling stations were selected; St.1 is the shellfish farm of razor clam near Jangsan area. St.2 is the shellfish farm of small ark shell near Hwapo area and St.3 is the shellfish farm of razor clam near Yongdu area. Razor clam was the dominant species at St.1, small ark shell and granulated ark shell were dominant at St.2 and St.3, respectively. Granulated ark shell inhabited St.3, although it is not cultured at that station. This station’s exposure to air during the ebb tide and sediment composition likely provides the appropriate habitat for granulated ark shell species. Analysis of the number of different species showed that 8 benthos species were found to be distributed at St.1, 18 species at St.2, and 13 species at St.3. Among three stations, the highest Ignition Loss (IL), Chemical Oxygen Demand (COD) and Acid Volatile Sulfide (AVS) values were obtained from the sediment at St.2. The analysis of pore water from St.2 also showed the highest values of Total Organic Carbon (TOC), ammonia (NH4 +), Dissolved Inorganic Nitrogen (DIN) and phosphate (PO4 3-). These results are related to the fact that species dominance and richness is the highest in St.2.

해양에 유출된 중금속은 빠르게 퇴적물과 결합하며, 해수보다 퇴적물에 수천 배 이상 높은 농도로 분포한다(Martin & Whitifield, 1983; Lee & Kim, 2000). 이매패류는 주로 해양저질에 서식하며, 여과 섭식을 한다. 따라서, 오염된 퇴적물에 서식하는 생물은 중금속에 직,간접적으로 악영향을 받을 수 있다(Luoma & Fisher, 1997; Yoo et al., 2002). 본 연구에서는 베트남 Ha Long Bay의 저질중금속 농도와 이 지역에 서식하는 이매패류 두 종의 intersexuality를 확인하고자 하였다. 저질중금속 분석은 ICP-MS(Perkin Elmer, NexION®300X)를 이용하여 측정하였다. 이매패류는 백합목(Veneroida), 재첩과(Corbiculidae)에 속하는 Polymesoda erosa와 개량조개과(Mactridae)에 속하는 Lutraria lutraria를 이용하였다. 시료는 Bouin 용액에 24시간 동안 고정하여 파라핀 절편법으로 4~6 ㎛ 두께로 연속 절편하였다. 그 후 Mayer's hematoxylin과 0.5% eosin(H-E) 비교염색을 실시하여 광학현미경으로 관찰하였다. Ha Long Bay 5개 지점의 저질중금속 농도는 Table 1과 같으며, 모든 지점에서 Al 농도가 가장 높았고, Cd 농도가 가장 낮았다. Intersex는 난소에서 수컷의 생식세포 또는 정소에서 암컷의 생식세포가 관찰되는 것을 기준으로 하였다. 성비는 P. erosa에서 1:0.4로 암컷의 비율이 더 높게 나타났고, L. lutraria에서는 1:4.5로 수컷의 비율이 더 높았다. Intersexuality는 P. erosa에서 14.3%, L. lutraria에서 9.1%로 두 종 모두 암컷에서만 관찰되었다(Table 2).

환경요인의 위해성 평가에 이용되는 biomarker 가운데 생식 및 조직학적 지표들은 독성물질에 의한 장기적이고 지속적인 영향을 평가하는데 중요하게 이용되는 항목이다(Huggett et al., 1992). 수질 오염원으로 확인되는 화학물질은 중금속, 난분해성 화학물질(persistent organic pollutants: POPs), 내분비계장애물질(endocrine disrupting chemicals: EDCs) 등이 있으며, 이매패류는 해양 저질과 수질의 오염상태를 알아보기 위한 지표종으로 많이 사용되고 있다. 본 연구는 한국 남해안 여자만에 서식하고 있는 우점종 이매패류를 이용하여 생태 건강도를 알아보고자 하였다. 연구에 사용된 이매패류는 여수 인근 여자만에 서식하는 바지락, Ruditapes philippinarum, 지중해담치, Mytilus galloprovincialis와 진주담치, M. edulis이다. 바지락은 여자만 인근 여수 이목리와 송여자도에서, 지중해담치와 진주 담치는 여수 이목리, 송여자도, 적금도와 고흥 백일도에서 2012년 5월부터 7월까지 채집하였다. 채집한 시료는 조직표본을 제작한 후 Mayer's hematoxylin-eosin(H-E) 염색, AB-PAS(pH 2.5) 반응과 Long Ziehl-Neelsen 염색을 실시하여 광학현미경으로 관찰하였다. Lipofuscin의 분포비율은 화상분석장치(IMT, Virsus, USA)를 이용하여 분석하였다. 체내 중금속 분석은 ICP-MS(Perkin Elmer, ELAN 6000)로 측정하였다. 바지락의 성비(♀:♂)는 여수 이목리와 송여자도에서 각각 1:1.10, 1:0.52로 나타났고, 지중해 담치와 진주담치는 여수 이목리에서 1:0.8, 1:1, 송여자도에서 1:1.25, 1:0.57, 적금도에서 1:1.67, 1:2, 고흥 백일도에서 1:0.44, 1:1.33으로 나타났다. Intersex 현상은 송여자도에 서식하는 바지락(13.8%), 지중해담치(11.1%)와 진주담치(9.1%)에서만 발견되었다. 조직학적 측면에서 intersex 현상은 반대 성의 생식세포들이 생식세포형성소낭 내부와 소낭 사이에 무리지어 나타나는 형태였다. 소화선에서는 모든 지역에서 공통적으로 소화선세관을 구성하는 상피세포와 호염기성세포의 변성과 결합조직층의 변성이 확인되었다. 특히 이목리와 송여자도에서 상피세포의 위축과 파괴가 관찰되었다. 소화선에서 lipofuscin의 분포비율(%)은 여수 이목리와 송여자도에 서식하는 바지락에서 각각 0.24, 3.14로 관찰되었으며, 지중해담치와 진주담치는 송여자도 7.17, 3.14, 이목리 1.16, 1.55, 적금도에서 4.81, 8.21과 고흥 백일도에서 3.51, 3.47로 확인되었다. 여자만에 서식하는 이매패류의 체내 중금속(Ni, Cr, Co, Al, Mn, Zn, Cu, Pb, Cd, As) 농도(mg/kg)는 바지락 2.49, 3.04, 0.53, 375.09, 19.25, 46.68, 8.39, 0.57, 0.34, 9.76, 지중해담치 3.93, 4.46, 0.75, 753.75, 26.72, 81.82, 7.86, 1.57, 1.54, 7.48와 진주담치 3.03, 0.69, 700.26, 28.95, 63.14, 7.87, 1.40, 1.39, 6.83로 나타났다.

This research was performed to simulate shellfish production systems and sales in Gamak Bay, South Korea. To study the way the shellfish system generates maxima, a numerical model was developed to simulate the model under a control and a number of different scenarios. The program calculates the EMERGY flows by multiplying the flows of energy and materials by the appropriate solar transformity. In this study, an energy systems model was built to simulate the variation of sustainability for oyster aquaculture. The results of the simulation based on 2005 data that as oyster production yield slightly increases, money and assets increase to a steady state. When the program is run control simulation, the system reaches carrying capacity after 8 years. The simulation of models with price of purchased inputs increased with 3.5% inflation rate per year showed maximum benefit of shellfish production occurs after 6 years but amounts are less than control simulation, and then decreases slightly in money and yield results. The results with 3.5% inflation and increase of oyster price annually showed steady and slightly increase of money and yield.

The objective of this research is to apply more scientific, quantitative methods and procedures of environmental investigation to the development of the natural environment and the improvement of the human environment during the establishment of a sewage treatment plant and special facilities using environmental accounting. This research was performed to develop a method of strategic environmental assessment on the operation of sewage treatment plant and reuse of shellfish seeding areas through the use of environmental accounting based on EMERGY evaluation. The result was applied to marine environment policy in order to evaluate the real wealth of the regional environment and economy for both the present phase and the proposed developed phase. Using results from the comparison of EMERGY indices between the present situation and future scenarios, cost benefit analysis was performed for three different scenarios: (1) construction of a new sewage treatment plant, (2) relocation and recovery of the shellfish seeding area , and (3) relocation and re-seeding of shellfish area and construction of a new sewage treatment plant. Cost-benefit ratios of the three scenarios are 1.88, 0.94, and 1.38, respectively.

This research outlines a new method for evaluation of shellfish production in Gamak Bay based on the concept of EMERGY. Better understanding of those environmental factors influencing oyster production and the management of oyster stocks requires the ability to assess the real value of environmental sources such as solar energy, river, tide, wave, wind, and other physical mechanisms. In this research, EMERGY flows from environment sources were 76% for shellfish aquaculture in Gamak Bay. EMERGY yield ratio, Environmental Loading Ratio, and Sustainability Index were 4.26, 0.31 and 13.89, respectively. Using the Emergy evaluation data, the predicted maximum shellfish aquaculture production in Gamak Bay and the FDA (Food and Drug Administration, U.S.) designated area in Gamak Bay were 10,845 ton/y and 7,548 ton/yr, respectively. Since the predicted shellfish production was approximately 1.3 times more than produced shellfish production in 2005, the carrying capacity of Gamak Bay is estimated to be 1.3 times more than the present oyster production.

To examine inshore radioactive contamination caused by nuclear power plants, nuclear testing, hospital and laboratory, both gross β-radioactivity and γ-spectrometry were measured. The measurements were taken with the Abalone and Top shell, which had been collected from the four different sites at the coast in Jeju-do (Seongsan, Deajeong, Wimi, Dodu). The activity ranges of concentration were respectively 0.11～0.29 Bq/kg-wet for 90Sr, 0.01～0.04 Bq/kg-wet for 137Cs, 36～53 Bq/kg-wet for 40K in shellfish on the Jeju island. The radioactivities of 90Sr, 137Cs and 40K were similar to those in sampling location of shellfish in the coastal on the Jeju island. The radioactivity of 90Sr for the Abalone was lower level than that for Top shell. The radioactivity of 137Cs for the Abalone was similar to that for the Top shell. But the radioactivity of 40K for the Abalone was higher level than that for the Top shell. As a result, the gross β-radioactivity observed was similar to that in nature. Among radionuclides, only 90Sr, 137Cs and 40K were detected in a very small amount, and each was also close to the natural levels.