| 摘要: |
| 2014年8月对渤海中部海域的水文(温度、盐度)、化学(溶解氧DO、营养盐和化学耗氧量COD)和生物要素(叶绿素a Chl-a)的空间分布进行了调查。研究了该海域底层水体低氧(DO< 3.0 mg/L)的分布特征，深入分析了低氧区发生的关键因素。结果显示，底层水体DO浓度最小值为 2.30 mg/L，低氧面积达1200 km2，呈西北–东南走向。调查海域的西部和西南海域呈现出明显的温度层化，尤其在低氧区附近形成了一个表层与底层水体温度差(δT)>5℃的区域，δT最高值达到7.3℃。水体密度层化与温度层化特征相似，在低氧区附近形成了一个底表层密度差(δρ)>2 g/L的等值线闭合圈。温度层化是低氧产生的主要物理因素。表层水体COD高值区主要分布在调查海域的西部，覆盖大部分的低氧海域。表层水体中的Chl-a (> 4 μg/L)和PO43--P (> 6 μg/L)浓度高值区主要分布在调查海域的西南部，部分与低氧区重合。本研究可为探索渤海海域富营养化演变过程提供借鉴。 |
| 关键词: 渤海中部海域 溶解氧 低氧 富营养化 |
| DOI：10.11758/yykxjz.20150618002 |
| 分类号: |
| 基金项目:农业部专项“渤海生态环境监测评估”(13-Q52201302)和黄海水产研究所级基本科研业务费项目(20603022015002)共同资助 |
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| Report on the Occurrence of Hypoxia in the Central Bohai Sea |
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JIANG Tao, XU Yong, LIU Chuanxia, ZHANG Yan, DING Dongsheng, SUN Xuemei, CHEN Jufa, CHEN Bijuan, ZHAO Jun, QU Keming
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Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Shandong Provincial Key Laboratory of Fishery Resources and Eco-Environment,Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071
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| Abstract: |
| Hypoxia in the central areas of the Bohai Sea was reported for the first time in this study. The survey in August 2014 suggested that the hypoxic zone was 1200 km2 in area and the minimum DO concentration was 2.30 mg/L. The hypoxic zone was on the southwest side of the investigated area (119.1°–119.6°E, 38.3°–38.8°N). The DO (4 mg/L) isoline indicated that the hypoxic layer reached 10 m under the water. There were differences in the temperature and density between the surface and the bottom layer (δT and δρ), implying the formation of strong pycnocline in the hypoxic zone. The δT isoline of 5℃ mainly occurred in the vicinity of hypoxic zone with the highest δT value of 7.3℃. The density difference between the bottom and the surface layer has a similar spatial pattern with δT. By contrast, the salinity difference between the bottom and the surface layer was small (< 0.8) in the investigated areas. These results suggested that thermal stratification could be more influential than saline stratification in controlling the occurrence of hypoxia. The COD concentration was high (< 0.9 mg/L) on the southwest side of the investigated area that accounted for the majority of the hypoxic zone. In addition, high level of Chl-a (> 4 μg/L) and PO43--P (> 6 μg/L) was also observed in this area. We proposed that the formation of hypoxia could be a result of combined factors including the inflow from the Yellow Sea, the topography, and especially, the thermal stratification and in situ production. |
| Key words: The central Bohai Sea Dissolved oxygen Hypoxia Eutrophication |
