Testing the fidelity of neodymium isotopes as a paleocirculation tracer in the Southeast Indian-Southern Ocean

GSTDTAP

项目编号	1737151
	Testing the fidelity of neodymium isotopes as a paleocirculation tracer in the Southeast Indian-Southern Ocean
	[unavailable]
项目开始年	2017
	2017-09-01
项目结束日期	2017-12-31
资助机构	US-NSF
项目类别	Standard Grant
项目经费	142643(USD)
国家	美国
语种	英语
英文摘要	In the modern open ocean neodymium (Nd) isotope values of seawater are often explained by the mixing of water masses. As such, Nd is recognized as a "quasi-conservative" tracer. Implicit in this "quasi-conservative" behavior is the assumption that no significant source of Nd exists along the water mass flowpath. This is the basic principle behind using Nd isotopes archived in marine sediments as a tracer of past ocean circulation. In recent years, several studies of Nd sources, sinks, and biogeochemical cycling has challenged this conventional wisdom and proposed additional sources of Nd, such as: (i) exchange with particulates that modifies seawater Nd isotope ratios, or (ii) addition of pore water Nd influenced by reactions with sediment. To successfully use Nd isotopes as a water mass tracer proxy, it is essential to understand these limitations. Therefore, this project will examine these alternative sources (and sinks) of Nd to evaluate their impact on the quasi-conservative behavior of seawater Nd. This research will help to constrain the limitations of Nd isotopes as a tracer of past ocean circulation. Funding supports career development for a postdoctoral researcher, provides field experience for a graduate student, and provides research experience for an undergraduate student. Project investigators will collect samples that constitute the different components of modern Nd cycle (e.g., filtered seawater, water column particulates, pore waters and concurrent down hole sediment samples) during a cruise in the Southeast Indian-Southern Ocean (SEISO). The SEISO cruise track will: (i) cover major water masses of Southern Ocean origin (Antarctic Mode Water, Antarctic Intermediate Water, Upper and Lower Circumpolar Deep Water), (ii) extensively transit over the southeast Indian Ridge, and (iii) sample the region just north of the Subantarctic Front, where Subantarctic Mode Water is forming today. Seawater and pore water Nd isotopes and Rare Earth Elements will be analyzed, thereby allowing characterization of the Southern Ocean water masses, the effects on seawater Nd isotopes from potentially reactive ridge rocks, and the influence of pore water Nd flux on bottom water Nd isotopes. Besides improving the understanding of Nd cycling, data from this project will provide important information for interpreting other datasets from the research cruise, and will be of interest to a wide range of climate scientists as well as biogeochemical modelers, chemical and biological oceanographers, and polar scientists.
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/71717
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	[unavailable].Testing the fidelity of neodymium isotopes as a paleocirculation tracer in the Southeast Indian-Southern Ocean.2017.