Radiocarbon in Dissolved Organic Matter in the Arctic Ocean

深海溶解有机碳（DOC）的平均放射性碳年龄在4000 ~ 6500放射性碳年之间。用于估计这一范围的数据集仅基于世界海洋中的几个地点，其中没有一个在北极。本提案的目的是确定北冰洋海水中大量DOC的放射性碳特征，以更好地了解单位体积陆地DOC接收量最高的地区DOC循环的时间尺度。参加一次前往北大西洋北部的巡航，以及另外两次前往欧亚盆地和加拿大盆地的巡航，计划从六个详细剖面收集水样。建议使用AMS（加速器质谱法）对每个站点水样中的DOC进行高精度放射性碳测量。本文将验证两个假设：(1)加拿大盆地（北极西部）的大块DOC比欧亚盆地（北极东部）的大块DOC早几百个放射性碳年，这些年龄可以用来确定北冰洋深海DOC的循环时间；(2)北大西洋北部（61 ~ 62.5°N）的大块DOC比欧亚盆地年轻，这是由于该地区深水地层中存在炸弹放射性碳。这些结果将为北冰洋DOC循环的时间尺度提供定量信息。这项资助将支持一名研究生和两名本科生的工作，并提供实践经验，为他们成为科学家和教育工作者做好准备。PI将在几个教育和专业级别开展外联和指导活动。

The average radiocarbon age of dissolved organic carbon (DOC) in the deep ocean ranges from 4000 - 6500 radiocarbon years. The data set used to estimate this range is based on only a few sites in the world ocean, none of which are in the Arctic. The objective of this proposal is to determine the radiocarbon signatures of bulk DOC in seawater from the Arctic Ocean to better understand the timescale of DOC cycling in the area that receives the highest amount of terrestrial DOC per unit volume than any other ocean. Participation in one cruise to the northern North Atlantic, and on two other cruises, to the Eurasian Basin and Canada Basin, is proposed to collect water samples from six detailed profiles. High-precision radiocarbon measurements are proposed using AMS (accelerator mass spectrometry) of DOC in water samples from each site. Two hypotheses will be tested: (1) bulk DOC in the deep Canada Basin (western Arctic) is several hundred radiocarbon years older than that in the deep Eurasian Basin (eastern Arctic), and these ages can be used to determine the cycling time of DOC in the deep Arctic Ocean; and (2) bulk DOC in the northern North Atlantic Ocean (61-62.5°N) is younger than in the Eurasian Basin, because of the presence of bomb radiocarbon in this region of deep water formation. These results will provide quantitative information on the timescale of DOC cycling in the Arctic Ocean. This grant will support the work of one graduate student and two undergraduate students and provide hands-on experience that will prepare them for careers as scientists and educators. The PI will conduct outreach and mentoring activities at several educational and professional levels.