| 摘要: |
| 于2013年3月和8月研究了长江口及其邻近海域叶绿素a的分布特征, 并对环境因子和长江冲淡水对浮游植物生物量分布的影响进行了探讨。结果表明, 叶绿素a浓度在丰水期较高, 平均值为5.18 μg/L,最高值达32.05 μg/L, 现场海水出现变色现象; 与同期历史资料对比分析, 发现该海域叶绿素a浓度呈现出波动增长趋势。丰水期与枯水期叶绿素a的相对高值区均位于冲淡水的中部, 122.5°E～123°E之间;丰水期在调查海域出现溶解氧低值区与低氧区, 最低值仅为0.64 mg/L;发现低氧区出现位置北移、面积扩大和溶解氧最低值下降的趋势。底层溶解氧低值区分布与表层叶绿素高值区大致吻合, 表明低氧现象与表层浮游植物的生长和现存量密切相关, 在跃层存在的水体中表层浮游植物的大量繁殖易造成底层低氧区的出现。 |
| 关键词: 叶绿素a 长江口 浮游植物 冲淡水 溶解氧 |
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| 基金项目:中国科学院战略性先导科技专项(A 类)资助(XDA11020302);国家基金委-山东省联合基金项目(U1406403); 中国科学院“百人计划”项目资助 |
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| Distribution of chlorophyll a and its correlation with the formation of hypoxia in the Changjiang River Estuary and its adjacent waters |
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LI Zhao,SONG Shu-qun,LI Cai-wen
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| Abstract: |
| Based on multi-discipline surveys in the Changjiang River Estuary and its adjacent waters in March and August 2013, the distribution of chlorophyll a (Chl a) as well as its correlation with major environment factors were studied. The results indicated that Chl a concentration was higher during the flood period, with an average of 5.18 μg/L and a maximum of 32.05 μg/L. The Chl a concentration during the flood period showed a fluctuating growth trend as compared to historical data, and the water containing a relatively high Chl a level appeared in the middle of the diluted area bounded by 122.5–123°E. A low level of dissolved oxygen (DO) and hypoxia was observed in the near-bottom waters during the flood period, with a minimum value of 0.64 mg/L. These results indicated that the hypoxic zone expanded and had a trend of moving northward, while the minimum DO value decreased significantly as compared to the historical records. The lower DO zone in near-bottom water was associated with the surface water with higher Chl a, indicating a close correlation between DO at the bottom and Chl a. Therefore, with strong water stratification, the flourishing of phytoplankton in the surface water may directly contribute to the formation of low-oxygen zones in near-bottom water. |
| Key words: chlorophyll a (Chl a) Yangtze River Estuary phytoplankton dilution water dissolved oxygen |
