南沙海域基于^234Th-^238U不平衡的颗粒态有机碳输出通量研究

Particulate organic carbon export fluxes in Nansha Islands sea area estimated from ^(234)Th-^(238)U disequilibria

利用234Th-238U不平衡方法研究南沙群岛海域春季真光层颗粒动力学性质,测定了4个站位水柱中颗粒态有机碳(POC)、溶解态及颗粒态234Th和238U的含量,讨论了各站位水柱中234Th/238U)A.R.的垂直分布。运用稳态箱式模型计算各站位不同水层中溶解态234Th相对于清除至颗粒物的平均停留时间和颗粒态234Th相对于迁出作用的平均停留时间。结合POC/234ThP比值,用两种方法估算出各站位的颗粒态有机碳输出通量分别为8.51—34.94和13.28—50.06mmol.(m2.d)-1。两种方法结果一致,说明234Th是表征POC循环的良好示踪剂。

Particle dynamics in the euphotic zone was studied at four stations in the Nansha Islands sea area during the 2002 spring cruise by the application of ^234Th-^238U disequilibria. The contents of the particulate organic carbon （POC）, ^234Th （dissolved and particulate） and ^238U were determined and the profiles of ^234Th/^238U）A.R. were discussed at the four stations. The profiles of dissolved and particulate 234Th and a steady state box model were used to quantify the dissolved ^234Th scavenging fluxes, particulate ^234Th re moval fluxes and their resident times. According to Poe/TM Thp ratios, the POC export fluxes at the four stations derived from the two different approaches ranged from 8.51 to 34.94 mmol/ ·（m^2·d）^-1 and 13.28 to 50.06 mmol/ ·（m^2·d）^-1, respectively.