Dissolved Organic Carbon (C13 and C14) Measurements, Beaufort Sea, 2012 USCGC Healy

Dissolved organic carbon (DOC) in the ocean is thousands of 14C years old, yet a portion of the DOC cycles on much shorter time scales (days to decades). We present 14C measurements of DOC in the Arctic Ocean and estimate that ≥8% of the DOC in the deep Eurasian basin contains bomb 14C. While this is a limited dataset, there appears to be selective loss of modern DOC in the surface and halocline waters of the open Beaufort Sea versus the Beaufort slope. At one of the Beaufort Sea stations, there is a linear relationship between DOC ∆14C values and previously measured total hydrolysable amino acid concentrations as reported by Shen et al. (2012), indicating that deep DOC contains small amounts of bioavailable DOC. The 14C data show that not all of the deep DOC is recalcitrant.

海洋中的溶解态有机碳（Dissolved organic carbon, DOC）的14C年龄可达数千年，但其中一部分DOC的周转时间尺度要短得多（数天至数十年）。我们开展了北冰洋DOC的14C同位素测定，并估算得出欧亚深层海盆中≥8%的DOC含有核爆14C（bomb 14C）。尽管本数据集存在一定局限性，但相较于波弗特海坡区域，开阔海域的波弗特海表层及斜温层水中似乎发生了现代DOC的选择性流失。在波弗特海的其中一个站位，DOC的Δ14C值与Shen等人（2012）报道的总可水解氨基酸浓度呈线性相关关系，这表明深层DOC中含有少量可生物利用的DOC。本次14C同位素数据表明，并非所有深层DOC均为难降解有机碳。