댐 방류에 따른 방류수는 직하류 하천과 하구부 및 연안에서의 다양한 수환경 변화를 발생시킬 수 있다. 본 연구는 주암조절지댐에서 방류된 방류수가 하류 하천과 연안에서의 수온 및 염분농도 변화에 미치는 영향을 파악하기 위해 EFDC 모형을 사용하였다. 대상구간은 주암조절지댐 직하류에서 부터 순천만까지이고, 지류하천인 상사천과 동천을 포함하였다. 모형의 재현성을 평가하기 위하여 하천과 하구부 지점에서의 수온 및 염분농도 관측값과 모의값을 비교한 결과 양호한 수준으로 재현됨을 확인하였다. 구축된 모형을 이용하여 댐 방류수의 수온과 방류량을 변화시킬 경우 하류 수온 및 염분농도에 미치는 영향을 평가하였다. 방류수 수온은 심층수와 표층수 방류조건을 비교하였고, 방류량은 실방류량과 방류량을 50%로 저감한 조건을 비교하였다. 비교결과 댐 방류수온의 영향은 댐 직하류에서 강하게 나타나지만 하류로 진행할수록 영향이 약화되며 외해역에서는 매우 미미한 영향이 발생하였다. 염분농도는 상류 댐 방류량이 외해 조위에 따른 해수교환량에 비해 작기 때문에 담수에 의한 염분농도 변화가 미미한 수준으로 나타났다.본 연구에서 구축한 댐-하천-연안 통합 3차원 분석모형은 향후 추가적인 보정을 통해 정확도를 보다 향상시키고, 수질 및 하상변동 기능을 포함하여 보다 다양한 분석이 가능할 것으로 판단된다.
The fertilized eggs of E. septemfasciatus are spherical and transparent with buoyancy at 790 to 890 μm (average 821.8±2.0 μm) in diameter with 170 to 230 μm oil globules (average 192.9±0.93 μm). Hatching began approximately 46 and 35 hours after fertilization at 22.0℃ and 25.0℃ water temperature, respectively. The average total length of newly hatched larvae was 1.75±0.03 mm. Most of the yolk and oil globules were absorbed within 3 to 4 days after hatching. The larvae reached 2.48 to 2.72 mm in total length, and their mouths and anuses opened at 3 to 4 days after hatching. In this time, the mouth diameters of the larvae were 0.209 to 0.238 mm. The larvae reached 3.24 to 4.15 mm in total length at 11 to 17 days after hatching, and began to metamorphose at the time the second dorsal and pelvic spines appeared and elongated. The abdominal cavity was densely lined with melanophores. The larvae reached 5.12 mm in total length at 24 days after hatching.
Physiological responses to salinity stress were evaluated in six rice genotypes differing in their tolerance to salinity at the seedling stage. Susceptible genotypes ('Dongjingbyeo', 'Hwayeongbyeo', and 'IR29') showed salt injury symptoms (mean 8.8) and higher visual score under salt stress than that of tolerant ones ('Pokkali', 'IR74009', and 'IR73571'). As salinity affects growth and physiological parameters, the six genotypes thus showed significant reduction because of salt stress. Tolerant Japonica/Indica bred lines ('IR74009', 'IR73571') showed lower reduction, 33.9%, 34.5%, and 50%, respectively, in plant seedling height, dry shoot weight and dry root weight than those of the susceptible Japonica varieties ('Dongjingbyeo', 'Hwayeongbyeo'), and the highest reduction under salt stress was observed in dry root weight, followed by dry shoot weight and seedling height, respectively. Shoot Na+ concentration of IR74099 and IR73571 was lower than that of the susceptible varieties, 'Dongjinbyeo' and 'Hwayeongbyeo'. There were no significant differences among genotypes in root Na+ concentration. Shoot K+ concentration showed a reverse tendency compared to shoot Na+ concentration. IR74009 and IR73571 had considerably lower ratio compared to 'Dongjinbyeo' and 'Hwayeongbyeo' in Na+/K+ ratio of their shoot and was not different the tolerant check, 'Pokkali'.
홍수 혹은 융설로 인한 대량의 담수유입은 만에서의 염분농도를 급격히 저하시키며, 그러한 변화는 근해 생물들의 서식환경을 파괴하는 경우도 있다. 그러므로 자연환경의 적절한 활용 및 생물들의 보호를 위해 만에서의 염분분포를 정량적으로 파악하는 연구는 매우 중요하다. 본 연구에서는 1차적으로 위성영상과 탁도와의 상관성을 조사하고, 2차적으로는 탁도와 염분농도와의 상관성을 이용하여 만에서의 염분분포를 구하였다. 본 연구의 주요 성과는 다음과 같다. 첫째 위성영
The solitary ascidian, Halocynthia aurantium, which is commonly called the sea peach because of its coloration and general shape, is a valuable organism of benthic marine population in the northern region of the East Sea, Korea. It is seldom found at a depth of less than 10 meters and the sea peach is frequently observed in large populations between 20 and 100 meters. It appears to prefer attachment to vertical rocks faces and artificial cement blocks exposed to the currents. Mass mortality and reduction of resources in sea peach, H. aurantium, were occurred in the benthic area of the northern region of the East Sea because of the rapid fluctuation of environmental factors such as temperature and salinity due to mass rainfall in summer and going up north of a strong warm current in winter. Therefore, we examined the effects of temperature and salinity on embryonic development of fertilized eggs, tadpole larva to metamorphosis, and attachment to siphon development. Laboratory-raised larvae were studied using a two-factorial experimental design with four levels of temperature(8, 12, 16 and 20℃) and four levels of salinity(20, 25, 30 and 34 psu). The ascidian larvae of H. aurantium survived environmental conditions between temperature of 8~20℃ and salinity of 25~34 psu and exhibited positive growth at 8~16℃ and 30~34 psu. Fertilized eggs have not developed at lower salinity of 20 psu irrespective of temperature range tested and have showed an abnormal development at the salinity of 25 psu between higher temperatures of 20 and 24℃. This result suggests that temperature increase and salinity reduction depending on environmental fluctuation may have significant impacts on population variation of H. aurantium in the northern region of the East Sea.
벼 내염성 유묘검정에서 실용성, 경제성, 정밀성이 우수한 검정체계를 확립하고벼 자포니카 내염성 중간모본 및 품종개발을 위한 내염성 유전자원 및 품종을 선발 이용하고자 본 시험을 수행하였다. 1. 증류수 이용 Yoshida 양액에 NaCl를 첨가한 염처리는 0.3%, 0.5%, 0.7%로 희석한 바닷물로 Yoshida 양액을 제조한 염처리 보다 유묘 내염성 계통을 선발하는데 효율적이었다. 2. 수돗물로 양액 제조 처리는 증류수로 양액 제조 처리와 유묘 내
The adverse effects of salinity and drought on soybean cultivar Hwangkeumkong were also investigated. Endogenous bioactive gibberellins GA1 and GA4, jasmonic acid (JA), abscisic acid (ABA) and salicylic acid (SA) content and pertinent changes in response to basic and double NaCl (70 mM & 140 mM) and PEG (8% & 16%) were examined. We found that plant growth and yield components significantly reduced with the application of NaCl and PEG during pre-flowering and post-flowering growth periods. The endogenous bioactive GA1 and GA4content decreased under elevated salt and drought stress. However, an insignificant increase in GA4level was noted with 8% PEG, applied during post-flowering growth stage. JA levels significantly increased with NaCl and PEG applications, but declined with elevated PEG applied during post-flowering period. SA level drastically reduced with NaCl, while insignificantly reduced with PEG. Endogenous ABA contents of leaves increased with elevated NaCl and PEG application. The endogenous bioactive GA1 and GA4, JA and ABA content of soybean leaves were analyzed through chromatograph/ mass spectrometer (GC/MS) in selected ion monitoring (SIM) mode, while SAcontent was quantified with HPLC.
Effects of salinity and standard toxic metals on fertilization and embryo development rates were investigated in the sea urchin, Strongylocentrotus nudus. Spawning was induced by injecting 1㎖ of 0.5 M KCl into the coelomic cavity. The fertilization and embryo development rates were below 20% when salinity was 25 psu or lower, but were above 90% when salinity was between 30 and 35 psu. The fertilization and embryo development rates in the control condition (not including Cu and Cd) were greater than 90%, but decreased with a high negative correlation (r) of 0.89 and 0.91 with the increasing of Cu and Cd concentrations, respectively. These results suggest that salinity concentrations for successful fertilization and normal embryogenesis of S. nudus are between 30 and 35 psu, and the biological assays of fertilization and embryo development rates using S. nudus are useful methods for the ecological toxicity test of marine pollution elements.
In order to investigate the effect of inflow of Yangze river on the distribution of chlorophyll-a, the results of serial oceanographic observation during 2000-2005 were used. The oceanographic conditions in the northern East China Sea is influenced by the Tsushima Warm Current and low saline water derived from the Yangze river. The distributions of these water masses vary significantly by the season in the northern East China Sea. The sea surface temperature and salinity were stable and concentrations of chlorophyll-a were low in the eastern part of 126°E. On the contrary, the salinity was significantly influenced by the low saline water derived from Yangze river with the high concentrations of chlorophyll-a. It is suggested that the low saline water inflowed from the Yangze river affects high concentrations of chlorophyll-a in the northern East China Sea in summer.
We examined the horizontal distribution of salinity and the concentrations of DIN and DIP after heavy rainfall events in coastal areas of South Korea from Yeoja Bay to Narodo and from Gwangyang Bay to Geomodo to determine whether fresh water actually flows into areas of Cochlodinium polykrikoides red tides and to observe its effect on the growth of this organism after heavy rainfall.
Following heavy rainfall (155 mm) in the Yeosu and Suncheon regions, the average salinity was 21 and 29 psu at Yeoja Bay and in the coastal waters of Narodo, respectively. After 126 mm of rainfall, the values were 19 and 25 psu in the coastal waters of Yeosu and Geomodo, respectively. This may have been caused by an influx of fresh water, after the rainfall event, into the open sea coastal areas around Narodo and Geomodo from the Dong and Seomjin Rivers, which are about 3540 km away. After the rainfall, the concentrations of NH4-N, NO2-N, and PO4-P were slightly increased; however, the concentration of NO3-N was greatly increased and diffused throughout the coastal areas of Narodo and Geomodo, which frequently experience C. polykrikoides blooms.
The influence of NH4-N, NO2-N, and PO4-P on the occurrence of C. polykrikoidesred tides in coastal areas around Narodo and Geomodo after heavy rainfall does not appear to be great. Instead, the occurrence C. polykrikoides red tides in the coastal areas of Narodo and Geomodo seems to be facilitated by NO3-N.
Based on the observation on 20, 23 and 26 July 2004, the distributions of temperature, salinity and stratification was investigated in relation to ebb, turn of tide and flood. The results are as follows: 1) The high temperature and low saline water with 23.5~24.0℃ and 32.4~33.0psu existed at Naro Island. 2) The cold surface water below 21.0℃ and 33.0~33.4psu appeared in the area near Gae Island and Geumo Island. 3) The cold and saline water, below 24.0℃ at the surface and 17.0℃ near the bottom, 32.8~33.8psu at the surface and 33.8~34.0psu near the bottom, existed in Sori Island. These waters were more saline compared to the South Sea Coastal Water with about 31.8psu. This suggests that the oceanic saline water intruded into the Bottol Bada through the area near Sori Island.
The stratification appeared during all the observation periods due to a high solar radiation of 22MJ/m2, and a weak wind speed of 2.9m/s on the average while the mean speed of wind in July is around 3.9 m/s. It qualitatively suggested that the stratification was maintained during the observation periods because of a high solar radiation, a weak wind speed and intrusion of saline oceanic water.