Characteristics of the Yellowish-Green-Colored Water-Zone in the Nakdong Estuary

洛東江 河口域에 出現하는 黃록色 水色帶의 特性에 關한 硏究

Water quality of seawater samples from ten stations was measured and analyzed to study the causes and the characteristics of the yellowish-green-colored zone in the Nakdong Estuary in February, May, August and October, 1984. The color of the yellowish-green-colored zone was equivalent to the grade 7 according to the Forel water-color meter and was observable throughout the year. The characteristics of the zone were low in transparency and high in the concentration of suspended solids, and about 52% of the suspended solids consisted of volatile substances. The chlorophyll a contents ranged from 0.4mg/$m^3$ to 51.0mg/$m^3$ and dissolved oxygen was in a state of supersaturation within the yellowish-green-colored zone. Nutrient concentrations were higher within the colored zone than the outside. Positive correlation was observed between tne concentrations of nutrients and chlorophyll a. Our results showed that the signficant portion of suspended solids sampled from the yellowish-green-colored zone consisted of phytoplanktons of which bloom was possibly induced by inflow of the nutrient-rich Nakdong River water.

洛東江 河口 一部 海域에서 觀察되는 黃綠色 水色帶의 發生原因과 性狀을 糾明하기 위하여 1984年 2月, 5月, 8月과 10月의 四次에 걸쳐 洛東江 河口의 10個 定點에서 水質調査를 實施하였다. 洛東江 河口 海域에 出現하는 黃綠色水色帶를 形成하는 것은 高 濃度의 浮遊物質로써, 그 中 平均 52%가 有機物에 該當하는 揮發性 浮遊物質로 構成되어 있다. 클로로필 a의 濃度는 黃綠色 水色帶 內部海域에서 平均 11.3mg/$m^3$이며, 最高 51.0mg/$m^3$으로써 周邊海域 및 他 海域에 比하여 매우 높은 濃度를 보이며, 溶存酸素는 過飽和 狀態이다. 營養鹽類 濃度도 黃綠色 水色帶 內部 海域이 外海側 海域보다 높고, 營養鹽類 濃度와 클로로필 a量과는 良好한 正의 直線的 相關關係를 나타낸다. 洛東江 河口 海域에 出現하는 黃綠色 水色帶는 洛東江에서 排出되는 土砂의 混濁뿐만 아니라 營養鹽類가 풍부한 洛東江 河川水의 影響으로 大量 繁殖한 植物性 플랑크톤의 發生으로 因한 것으로 보인다.