본 연구는 8월에 한반도를 우회하며 동해상으로 빠져나간 2018년 제 19호 태풍 Soulik과 서해상으로 북진하여 통과한 2020년 제 8호 태풍 Bavi을 통해 태풍 유입 전‧후에 따른 한반도 해역별 수온 변동성을 분석하였다. 분석자료는 국립수산과학원 실시간 수온 자료와 수온관측소 근처 AWS의 바람자료 및 NOAA/AVHRR 위성 수온자료를 활용하였다. 분석 결과 이동경로가 다른 태풍이 한반도를 통과할때 동해에서는 풍속과 풍향에 따라 수온의 상승(북풍)과 하강(남풍)이 반복적으로 발생하였는데 특히 태풍 Soulik 유입 시 10 ℃ 안팎의 급격 한 수온 하강을 보였다. 서해는 태풍 Bavi의 중심부가 통과되면서 서해 일부 해역에서 수온이 상승되었고, 차가운 물덩어리가 존재했던 남 해 일부 해역에서도 태풍 Bavi의 이동으로 따뜻한 수온이 유입되어 평년 수온으로 회복된 것으로 나타났다. 또한 태풍 유입시 서해와 남해 는 지형적‧환경적 조건으로 인해 각 해역별 특성에 맞게 수온 변동이 다르게 나타났다. 본 연구를 통해 태풍으로 인한 한반도 해역별 수 온 변동을 해석함으로써 이상기후에 따른 양식 생물의 부정적인 영향을 최소화하고 해역별 수산재해의 피해대응 전략을 수립하는데 기여 할 것으로 사료된다.
Microplastics and nanoplastics (NMPs) are considered one of hazardous contaminants in marine ecosystems due to their toxic effects, such as reproduction disorder and oxidative stress, on marine organisms. Although water temperature is rising due to global climate change, little information on the toxicological interaction between NMPs and temperature is available. Therefore, in this study, we confirmed the toxicity of NMPs (polystyrene [PS] beads; 0.05- and 6-μm) on brackish water fleas (Diaphanosoma celebensis) depending on increased temperature (30°C and 35°C) at individual and molecular levels. In the chronic toxicity test, the group exposed to high temperatures showed an earlier first reproduction time compared to the normal temperatures group, but it was delayed by co-exposure to NMPs at 35°C. Notably, the total reproduction decreased significantly only after 0.05-μm PS beads exposure at 30°C. Interaction analysis showed that first reproduction time, modulation of the antioxidantrelated gene (GSTS1), heat shock gene (Hsp70), and ecdysteroid pathway-related genes (EcR_A, EcR_B, and CYP314A1) were closely related to temperature and PS beads size. These results indicate that microplastics have size-dependent toxicity, and their toxicity can be enhanced at high temperatures. In addition, higher temperatures and PS beads exposure may have negative effects on reproduction. This study suggests that various factors such as water temperature should be considered when evaluating the toxicity of microplastics in marine ecosystems, and provides an understanding of the complex toxic interaction between water temperature and microplastics for marine zooplankton.
Change in chemical constitution of a zirconium sample treated at the simulated condition of a pressurized water reactor (water at 315°C and 15.5 MPa) was investigated using X-ray diffraction (XRD) and Raman spectroscopy. We observed swelling of the zirconium sample as well as the change in its color from silver to gray treated after the pressurized water at high temperature. On the basis of XRD and Raman data, we confirmed that the variation in composition of zirconium specimen from hexagonal Zr to monoclinic ZrO2 occurred at the simulated PWR condition. Therefore, we suggested that the oxidation of zirconium appeared due to the reaction with water at high temperature and pressure, as shown in the following reaction: Zr + 2H2O → ZrO2 + 2H2.
Surface water temperature of a bay (from the south to the north) increases in spring and summer, but decreases in autumn and winter. Due to shallow water depth, freshwater outflow, and weak current, the water temperature in the central to northern part of the bay is greatly affected by the land coast and air temperature, with large fluctuations. Water temperature variations are large in the north-east coast of the bay, but small in the south-west coast. The difference between water temperature and air temperature is greater in winter and in the south-central part of the bay than that in the north to the eastern coast of the bay where sea dykes are located. As the bay goes from south to north, the range of water temperature fluctuation and the phase show increases. When fresh water is released from the sea dike, the surrounding water temperature decreases and then rises, or rises and then falls. The first mode of empirical orthogonal function (EOF) represents seasonal variation of water temperature. The second mode represents the variability of water temperature gradient in east-west and north-south directions of the bay. In the first mode, the maximum and the minimum are shown in autumn and summer, respectively, consistent with seasonal distribution of surface water temperature variance. In the second mode, phases of the coast of Seosan~Boryeong and the east coast of Anmyeon Island are opposite to each other, bordering the center of the deep bay. Periodic fluctuation of the first mode time coefficient dominates in the one-day and half-day cycle. Its daily fluctuation pattern is similar to air temperature variation. Sea conditions and topographical characteristics excluding air temperature are factors contributing to the variation of the second mode time coefficient.
This study aims to select eggplant cultivars adaptive to the hot temperature period greenhouse climate by water consumption, and growth performance of plants and fruits of different European eggplant cultivars, including ‘Bartok (BA)’, ‘Bowie (BO)’, ‘Black Pearl (BP)’, ‘Ishbilia (I)’, ‘Mabel (M)’, ‘Vestale (VE)’ and ‘Velia (VL)’, in substrate hydroponic cultivation under hot and humid greenhouse conditions. On the 118 DAT, the leaf number and stem dry weight were highest in ‘VL’, followed by ‘M’, and there was no significant difference in leaf dry weight among cultivars. The marketable fruit number per plant was 16.4 for ‘M’, which was higher than other cultivars, and ‘VE’ and ‘VL’ were 8.5 and 8.8, respectively. The weight per fruit was low for ‘M’ at 136 g, and the highest in ‘VE’ and ‘VL’ at 332 and 281 g, respectively. There was no significant difference in fruit production per plant. In this study, ‘M’, which has high water use efficiency and a large number of fruits, and ‘VL’, which required less quantity to water consumption for producing 200 g of fruit and had a high product weight, will have excellent adaptability in the UAE greenhouse condition.
This study was conducted to evaluate the filtration performance according to the feed temperature composed of NaCl and the operating pressure of the brackish water reverse osmosis (BWRO) process. The temperature is known that decides the filtration performance of reverse osmosis (RO). It is noted that temperature increase activates the permeate of salts due to augment of diffusivity and mass transfer. Filtration of the lab-scale RO system was performed with constant pressure and the constant flow was simulated. The salt rejection measured by the concentration of the feed and permeate was compared with water permeability and salt permeability in the conditions containing various temperatures (5, 10, 15, 20, 25, and 30℃) and pressures (10, 12, 15, and 18 bar). An increase in feed temperature from 5 °C to 30 °C caused a 4.65% decrease in salt rejection in CSM, due to an increase in salt permeability (4.06 times) rather than an increase in water permeability (2.62 times). Specific energy consumption (SEC) was calculated by using an electricity meter set in the RO system. It was expected that the SEC by the increases in temperature and pressure decreased due to the viscosity decline of the feed and the permeate flux augment, respectively. The SEC decreased by 63.4% in CSM and by 54.3% in Nittodenko when the feed temperature increased from 5 °C to 30 °C. It discussed how to operate the optimal RO process through the effect of temperature and operating pressure and the comparison of SEC.
동해연안의 반폐쇄성 해역인 영일만에서 고주파해양레이더(HF-Radar)로 측정된 표층 해수유동 자료를 활용하여 1)바람과 수평 적인 해수유동 사이의 상관성을 파악하고 2)수직적으로 조밀한 간격의 층별 수온시계열 자료와 연계하여 수평적 및 수직적 해수유동의 특성을 파악하였다. 시계열 관측기간 중 영일만 해역의 전역에 걸쳐 북동풍이 우세하게 나타났을 때 표층부터 저층까지 수온의 급격한 상승이 동반되었다. 또한 표층의 장주기 해수유동에서도 풍향과 유사한 방향의 흐름이 뚜렷하게 관측되었다. 바람과 표층 해류 사이의 지 연상관 분석을 통해 영일만에 북동풍의 바람이 불기 시작하여 일정하게 지속된다면 짧은 시간(1 ~ 2시간) 내에 남서향의 표층 해류가 발 생되는 것을 확인하였다. 일평균된 장주기 표층 해류로부터 수렴과 발산을 계산하였고 이를 통해 층별 관측지점에서 발생한 두 번의 급 격한 저층수온 상승이벤트가 모두 영일만의 북동풍과 연관된 표층 해수(상대적 고온수)의 수렴(침강) 현상으로 인해 나타난 것으로 판단 하였다.
This study was conducted to investigate the effects of different water temperatures (8, 11, 14 and 17°C) on growth, survival and hematological parameters of juvenile chum salmon (Oncorhynchus keta) for eight weeks. At the end of the experiment, at 14°C, the final body weights of the O. keta group were the highest compared to the other groups. Also, the O. keta showed a higher tendency in the 14°C group than the 8, 11, and 17°C groups in terms of growth performances, including specific growth rate (SGR), feed conversion ratio (FCR), feed efficiency (FE), weight gain (WG), and condition factor (CF). The survival rate (SR) was 100% at 8 and 11°C groups, 96% at 14°C group and 98% at 17°C group. In the plasma components, the alanine aminotransferase (ALT) was significantly decreased at 17°C group, whereas there was no significant change in the albumin (ALB), total protein (TP), sodium (Na+), potassium (K+) and chloride (Cl-) levels. Among the whole-body composition of salmon, moisture, crude protein, and ash were not significantly affected by water temperature. However, crude lipid in the 8°C group was significantly higher than in other water temperature groups. The results of this study demonstrated that the optimal temperature to stable growth performance for juvenile O. keta was 14°C.
본 연구는 저염분 상태에서 수온 및 사육밀도와 같은 환경요인이 흰다리새우(Litopenaeus vannamei)의 성장에 미치는 영향을 조사하기 위하여 수행하였다. 연구 결과, 흰다리새우는 저 염분 상태에서 전반적으로 수온이 높을수록 생존율이 높게 나타났고, 사육밀도가 낮을수록 생 존율이 높아졌다. 사료효율에 관한 연구에서는 수온이 높을수록 증체량(WG)이 증가하였고, 사 육밀도가 증가할수록 증체량은 감소하였다. 수온이 높을수록(수온 31℃) 성장 속도가 빨랐다. 또한 사육밀도에 따른 성장도의 평가에서도 사육밀도가 낮은 상태에서 성장 속도가 빨라지는 것을 확인하였다. 본 연구 결과를 흰다리새우의 최적 성장을 위한 적정 사육밀도 및 사육수온 의 결정에 유용하게 적용되리라 사료된다.
수송은 양식어류의 양식과정에서 필수적으로 수행되며, 선별과 같은 물리적인 스트레스 요인 중 하나이다. 이러한 이유로 본 연구에서는 해산어류인 넙치를 이용하여 수송 시 염분, 수온 및 마취제의 영향을 확인하기 위해 수송 시 해수 염분(35‰, 15‰)과 수온은 20℃ (natural water temperature, NWT), 15℃ (cooling water temperature, CWT)로 설정하였으며 마취제(anesthesia, Anes., Sigma USA)는 50 ppm 희석하여 염분, 수온, 마취제 요인들을 혼합한 실험구를 설정하였 다. 실험구는 각각 NWT+35‰, CWT+ 35‰, NWT+15‰, CWT+15‰, NWT+15‰+Anes. 및 CWT+15‰+Anes.으로 설정하였다. 스티로폼 상자(66×42×20 cm)를 수송용기로 사용하였으 며, 해수 3 ℓ와 액화산소를 주입한 비닐봉지에 넙치 8마리씩 수용하여 수송하였다. 연구 결과 수송 전 코티졸 농도는 2.4±0.1 ng ml-1로부터 CWT+35‰ 구(16.7±12.8 ng ml-1)를 제외한 나 머지 실험구에서 유의하게 높아졌다. K+ 농도는 수송 전 3.1±0.0 mEq l-1로부터 NWT+15‰ 구에서 4.5±1.1 mEq l-1로 차이를 보이지 않았으나, 나머지 실험구에서는 모두 유의하게 높은 값을 보였다. 혈액성상의 변화에는 영향을 미치지 않았으며, 수온과 마취제는 스트레스를 유발 로 인한 삼투압조절에 부정적인 영향을 미쳤다. AST, ALT에는 영향을 미치지 않았다.