^(234)Th示踪法估算楚科奇海的颗粒有机碳输出通量

234Th as a tracer of particulate organic carbon fluxes in the Chukchi Sea

为了研究楚科奇海生物泵过程,利用234Th示踪法估算了该海区真光层颗粒有机碳的输出通量。测定了中国第2次北极考察期间获得的楚科奇海测站海水样品中溶解态及颗粒态234Th、238U和颗粒有机碳的含量。基于上层水体中234Th与238U的不平衡并结合一维稳态不可逆清除模型,估算出了真光层中溶解态234Th的清除速率、颗粒态234Th的迁出速率、234Th的平均停留时间等颗粒动力学参数以及颗粒有机碳的输出通量和ThE比值(颗粒有机碳输出通量和初级生产力的比值)。楚科奇海具有较高的颗粒有机碳输出通量和很高的ThE比值,生物泵运转活跃,是全球碳循环的重要汇区。

^ 234 Th was utilized as a tracer of particulate organic carbon fluxes from the euphoric zone to study biological pump process in the Chukchi Sea. The depth profiles of particulate organic carbon （POC）, ^234Th （including both dissolved and particulate） and ^238U in the upper water column at one station in the Chukchi Sea were determined during the Second Chinese National Arctic Expedition （CHINARE）. The ^234 Th/^238 U disequilibria in the upper waters and one-dimensional irreversible steady state model were used to calculate the particle dynamic parameters （i. e. , the dissolved ^234Th scavenging rates, the particulate ^234Th removal rates and their resident times） and the POC export fluxes as well as the ThE ratio （the ratio of POC fluxes to primary production） in the euphotic zone. The high POC export fluxes and the ThE ratio show that the Chukchi Sea with an actively running biological primp is an important sink in the global carbon cycle.