长江口邻近海域溶解氧分布特征及主要影响因素

Distribution and Main Influence Factors Process of Dissolved Oxygen in the Adjacent Area of the Changjiang Estuary in Autumn

根据2002年11月5~10日对东海长江口邻近海域(29.0°N^32.0°N,122.0°E^124°E)的现场调查数据,初步分析了调查海域秋季溶解氧分布特征及主要影响因素。结果显示:调查海域秋季溶解氧平面分布整体上呈近岸高、外海低,表层高、底层低的分布趋势,在约20m深度存在溶解氧跃层。调查海域溶解氧饱和度均<100%,表观耗氧量最高达4.0mg/L,氧不饱和状态由表层至底层逐渐加剧,在123°E附近底层仍然存在明显的溶解氧低值区,但其溶解氧含量已较夏季有所回升,含量范围在3.31~8.47mg/L之间,平均为(6.73±1.09)mg/L。该海域秋季溶解氧分布主要受物理过程控制,生物活动仅在底层溶解氧低值区有较大的影响。

An autumn cruise was carried out from Nov. 5th to 10th 2002 in the East China Sea, covering an area from 29.0°N to 32.0°N and 122.0°E to 124.0°E, with the purpose of making a primary study on the spatial distributions and the influence factors of dissolved oxygen （DO） in the adjacent areas of the Changjiang Estuary. The horizontal distribution of DO was in a decreasing trend from coastal waters to the open sea, while the vertical distribution was in a decreasing trend from the surface to the bottom. At the same time, spring layers were found at the depth of about 20m at some sections. On the whole, the saturation rate of DO in the study area was below 100 %, while the maximal apparent oxygen utilization （AOU） was as high as 4.0mg/L. And a lower oxygen area was found to be at the bottom of the adjacent areas of the Changjiang Estuary. The insitu data showed that the DO concentration varied from 3.31 to 8.47mg/L., the mean being （6.73 ± 1.09）mg/L. The DO in the study area in autumn was dominated by the physical processes rather than the bio disturbance, which was considered to be neglectable.