Particulate organic carbon export fluxes estimated from ~(234)Th/~(238)U disequilibria in the Xiamen Bay | 厦门湾水体中颗粒有机碳的垂向输出通量:~(234)Th/~(238)U不平衡的应用
2002
陈敏 | 黄奕普 | 邱雨生
对厦门湾塔角附近海域某站位叶绿素 a、POC、初级生产力、234Th/238U不平衡进行的周日变化研究表明,POC含量介于14.4～34.6 mmol/m3之间,其中碎屑有机碳与活体有机碳所占份额分别为74％～92％和8％～26％.POC垂直分布呈现由表及底降低的趋势,且白昼期间POC含量高于晚间,说明研究海域POC含量与生物过程具有密切联系.初级生产力水平在1d之中变化达5倍,垂直分布亦随深度增加而降低,与叶绿素a的变化相对应.短时间（2h）培养获得的初级生产力水平明显高于长时间培养（24 h）的结果,证实部分新固定的碳被优先呼吸排出.结合234Th/238U不平衡法获得的颗粒态234Th输出通量及输出界面颗粒物中的POC/PTh比值,可计算出真光层 POC的垂向输出通量为16.0mmol/（m2·d）,其中碎屑有机碳与活体有机碳贡献的数量分别为13.3和2.7mmol/（m2·d）.POC输出通量与初级生产力的比值（ThE比值）平均为0.31,真光层POC停留时间平均为11d.上述结果与Aksnes和Wassmann[1]的模型计算结果相吻合,但与其他大多数模型的结果仍存在一定的差异. 【英文摘要】 The daily variations of Chi. a, POC, primary production and 234Th/238U disequilibria in the Xiamen Bay were studied. POC concentration in the study area ranged from 14. 4 to 34. 6 mmol/m3, with an average concentration of 21. 6 mmol/m3. The contributions of living organic carbon (phytoplankton) and organic detritus were estimated to be about 8% ~ 26% and 74% ~92% of the total POC, respectively. The profiles of POC showed a gradually decrease with the depth, and its temporal variation showed that the POC con...
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