The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY (한국해양학회지:바다)
- Volume 5 Issue 1
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- Pages.16-26
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- 2000
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- 1226-2978(pISSN)
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- 2671-8820(eISSN)
The Outbreak of Red Tides in the Coastal Waters off Kohung, Chonnam, Korea: 1. Physical and Chemical Characteristics in 1997
전남 고흥 해역의 유해성 적조의 발생연구: 1.물리${\cdot}$ 화학적인 특성
- Yang, Jae-Sam (Department of Oceanography, Kunsan National University) ;
- Choi, Hyun-Yong (Department of Oceanography, Kunsan National University) ;
- Jeong, Hae-Jin (Department of Oceanography, Kunsan National University) ;
- Jeong, Ju-Young (Department of Oceanography, Kunsan National University) ;
- Park, Jong-Kyu (The Institute of Environmental Research, Inje University)
- Published : 2000.02.29
Abstract
Physical characteristics and nutrient distributions in seawater were investigated to understand the mechanism of red tide outbreak in coastal waters off Kohung area. To identify any physical and chemical differences before, during and after the red tide outbreaks, 6 times of field observations have been carried out from May to October, 1997. We found that major environmental properties of the seawater in the study area were determined not by the local meteoric conditions or nearby-land influences, but by the intrusion of seawater from offshore. In particular, extreme environmental variations in seawater were found during the period of red tide outbreak from August to September. Before the red tide outbreak, high concentrations of DIN(Dissolved Inorganic Nitrogen)were found in seawater, but they decreased during the outbreak. Whereas no significant variations of DIP(Dissolved Inorganic Phosphate) were found. For the water mass in the semienclosed northern part of the study area, local nutrient sources originated from nearby-lands were estimated to cover 70% of total DIN input, but the rest part of the water mass in the study area, sporadic intrusion of offshore water mass could account for the major source of DIN supply. An offshore water mass influenced by Yangtze river effluent was suggested as one of the candidates with its high nitrate contents, high seawater temperature and low salinity. A red tide related phytoplankton, Gyrodinium impudicum, was found in seawater on the 21th day of August and, on the same day, a unique water mass with high temperature and extremely low salinity suddenly appeared in the study area. On the 22th day of September, after one and half month duration of red tide we found that red tide had disappeared simultaneously with the intrusion of new water mass with different characteristics.
비내만성 적조가 빈발하는 남해안 고흥 해역에서 1997년 5월에서 10월까지 적조발생 이전, 도중 그리고 이후 등 총 6차에 걸쳐 해수 물성 및 영양염의 분포를 조사하였다. 연구해역의 해수특성 변화 및 수층구조는 국지적인 기상조건이나 인접한 육지의 영향보다는 외해역에서 유입되는 해수의 특성에 따라 변화하였다. 특히 적조 발생기간인 8월에서 9월 사이에 극심한 해수환경의 변화가 발견되었다. 적조발생 전에는 주변환경에 비하여 높은 농도의 용존무기질소가 관측된 반면, 적조가 발생한 기간에는 오히려 농도가 낮아졌다. 그러나 용존무기인 농도의 변화는 발견되지 않았다. 연구해역의 북측 내만은 인근 육지에서 공급된 용존무기질소의 양이 전체 유입량의 70%를 차지하고, 그 외의 해역에서는 외해로부터 유입된 수지(flux)가 전체 유입량의 98%로 주 유입원이 된다. 이와 같이 높은 영양염과 고온
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