^(234)Th示踪法测定北太平洋西北海域冬季真光层中颗粒态有机碳输出通量  

Particulate organic carban fluxes from euphotic zone estimated with ^(234)Th deficiency in winters in the northwestern North Pacific Ocean

作　　者：杨永亮[1,2] 韩旭[2] 日下部正志 

机构地区：[1]国家地质实验测试中心 [2]青岛大学环境科学与工程系,山东青岛266071 [3]日本放射线医学综合研究所那珂凑支所 [4]日本海洋科学技术中心,横须贺237-0061

出　　处：《海洋学报》2005年第1期84-92,共9页

基　　金：国家自然科学基金资助项目(40173027);日本高纬度海洋物质循环计划资助项目.

摘　　要：讨论了1997年冬季在北太平洋西北海域7个站位的表层至200m水深水柱中溶解及颗粒态234Th,颗粒态有机碳(POC)、氮(PON)及叶绿素a浓度的垂直分布剖面.溶解态、颗粒态及总的234Th的放射性在真光层中显著低于母体238U的放射性,总的234Th放射性在水深大于100m时趋于平衡.利用234Th-238U在海洋表层海水中的放射性不平衡推导出了北太平洋西北海域冬季真光层海水中234Th的平均停留时间和输出通量以及颗粒态有机碳和有机氮的输出通量.在亚北极环流区溶解态234Th的停留时间为40~50d,而在黑潮-亲潮共同影响区为20d左右.颗粒态有机碳和有机氮从真光层的输出通量范围分别为3 8~8 2和0 50~0 98mmol/(m2·d),西部海区高于东部海区,南部海区高于北部海区.在黑潮-亲潮共同影响区较高的颗粒态有机碳输出通量表明光照量及陆源营养盐物质的提供是两个决定生产力的主要因素.叶绿素a的水深分布和POC/PON的值同Redfield的比值的一致性表明这个海区的冬季颗粒物主要由浮游植物构成.北太平洋西北海域在冬季的颗粒有机碳输出通量可高于世界大洋一些海区春、夏季的颗粒有机碳输出通量.Dissolved and particulate ^(234)Th,particulate organic carbon (POC),particulate organic nitrogen (POC),and chlorophyll a concentrations in the upper 200 m of water columns from seven stations in the northwestern North Pacific Ocean were determined in the winter of 1997. The dissolved,particulate,and total ^(234)Th activities (dissolved plus particulate) show a pronounced deficiency with respect to its parent ^(238)U in the euphotic zone whereas the total ^(234)Th shows near-equilibrium at the depth greater than 100 m. The ^(234)Th data were used to derive the fluxes of particulate organic carbon and nitrogen output of the euphotic zone. The POC and PON fluxes range from 3.8 to 8.2 and 0.50 to 0.98 mmol/(m^2·d),respectively,and are higher in the west region than in the east,and higher in the south than in the north. The co-influence of Kuroshio-Oyashio Currents with supply of substances from the coast area to the study area and the light condition are two factors determining the horizontal distribution of POC fluxes in winter. The depth distribution of the chlorophyll a as well as the consistence of the ratio of POC to PON with the Redfield ratio suggest that phytoplankton is the main contributor to the export of POC in this area in winter. The POC fluxes in the northwestern North Pacific Ocean in winter are comparable to some areas in the world oceans in spring and summer seasons.

关 键 词：^234Th 北太平洋 有机碳 有机氮 输出生产力 

分 类 号：P722.5[天文地球—海洋科学]