IDENTIFICATION OF A DEEP MARINE SOURCE OF PARTICULATE ORGANIC-CARBON USING BOMB C-14
IDENTIFICATION OF A DEEP MARINE SOURCE OF PARTICULATE ORGANIC-CARBON USING BOMB C-14
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DOI：
10.1038/347172a0
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发表时间：
1990-09-13
期刊：
影响因子：
64.8
通讯作者：
WILLIAMS, PM
中科院分区：
文献类型：
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作者：
DRUFFEL, ERM;WILLIAMS, PM
通过对北太平洋浮游生物进行放射性碳年代测定，评估了炸弹放射性碳（14 C）流入海洋食物链的情况1，2。这些研究发现深度存在显着梯度，为Δ 14 C（与十九世纪木材标准活性的每密耳偏差）。根据长期存在的关于水柱中碳循环的假设3 -5，预计不会出现这种梯度;相反，人们可以预计，到1970年左右（炸弹放射性碳产生后10-20年），整个水柱中生物体的Δ 14 C将与地表水溶解无机碳（DIG）中的Δ 14 C相等。在这里，我们提出的Δ 14 C值测量的悬浮和下沉颗粒有机碳（POC）从公海网站和沿海盆地的配置文件。悬浮态POC的14 C活性随深度的增加而显著降低，与生物体中的14 C活性相同，而下沉态POC的14 C活性仅略低于表层DIC和表层悬浮态POC。然而，所有POC Δ 14 C结果均大于相应的爆炸前、表面衍生DIC值，因此包含爆炸14 C。这种14 C活性的降低需要一个深层的碳源（或多个碳源）进入次表层POC池。涉及低14 C活性溶解有机碳（DOC）的吸附过程可能提供降低悬浮和（在较小程度上）下沉POC中Δ 14 C值的机制。
THE influx of bomb radiocarbon (14C) into the oceanic food chain has been evaluated by radiocarbon dating of pelagic organisms in the North Pacific1,2. These studies found a significant gradient with depth of Δ14C (the per mil deviation from the Standard' activity of nineteenth century wood). Such a gradient is not expected according to long-standing assumptions about carbon cycling in the water column3–5; instead, one could expect the Δ14C of organisms throughout the water column to have become equal to that in surface-water dissolved inorganic carbon (DIG) by about 1970 (10–20 years after the production of bomb radiocarbon). Here we present Δ14C values measured in the profiles of suspended and sinking particulate organic carbon (POC) from an open-ocean site and a coastal basin. The14C activity of suspended POC decreases significantly with depth, as is observed in organisms, whereas that of sinking POC is only slightly lower than that in surface DIC and surface suspended POC. All POC Δ14C results, however, are greater than the corresponding pre-bomb, surface-derived DIC values, and therefore contain bomb14C. This decrease in14C activity requires a deep source (or sources) of carbon to sub-surface POC pools. Adsorptive processes involving low-14C-activity dissolved organic carbon (DOC) may provide a mechanism for lowering Δ14C values in suspended and (to a lesser extent) sinking POC.