U.S. GEOTRACES PMT: Measurement of the organic complexation and chemical lability of dissolved copper using multiple techniques

GSTDTAP

项目编号	1756415
	U.S. GEOTRACES PMT: Measurement of the organic complexation and chemical lability of dissolved copper using multiple techniques
	James Moffett
主持机构	University of Southern California
项目开始年	2018
	2018-03-01
项目结束日期	2021-02-28
资助机构	US-NSF
项目类别	Standard Grant
项目经费	263342(USD)
国家	美国
语种	英语
英文摘要	Copper (Cu) is an element in the ocean that is essential for life. Like many elements taken up by marine life, its concentrations in seawater are very low; however, Cu has a distribution in the water column that is different from other biologically essential elements. This difference may be attributed to the presence of a residual fraction in seawater that is virtually inert. This project seeks to understand what this material is, why it is so unreactive, and how it can eventually be 'cracked" and re-enter the biological cycle. A scientist from the University of Southern California (USC) will characterize the Cu chemistry during the US GEOTRACES Pacific Meridional Transect (PMT) cruise. This cruise is a north-south transect from Alaska to Tahiti that spans a wide range of water depths, temperatures, biology, and chemistry. The Cu measurements will be made alongside many other trace elements that have different chemistries. By comparing their behavior, coupled with the knowledge of each element?s chemical properties, the scientist will further our knowledge of what controls the behavior of Cu in the ocean. Training of graduate students and outstanding undergraduates in the speciation techniques is planned. The graduate students will also mentor high school students from inner city schools through the USC Young Investigators Program. The cruise and its findings will be incorporated into outreach activities and courses taught at USC, including a general education class for non-science majors. A scientist from USC hypothesizes that non-labile complexes will predominate in high-scavenging regimes and that labile forms will accumulate in older deep waters above a non-labile background pool. To quantify the distribution and chemical properties, two different speciation techniques will be used based on competitive ligand exchange. The first, adsorptive cathodic stripping voltammetry, was used on previous GEOTRACES sections. The second is based on a ligand exchange, liquid/liquid partition methodology developed by the researcher. Partitioning leads to physical separation of fractions that are reactive or not with the competitive ligand allowing the exchangeability of strongly complexed copper by using Cu-65 as a tracer. The tracer enables much slower reactions to be studied experimentally. Samples will be analyzed using isotope dilution by inductively coupled plasma-mass spectrometry. Samples will also be prepared for natural Cu isotope analysis of non-labile Cu by a colleague at USC (Seth John) to test the hypothesis that non-labile or semi-labile complexes contribute to the heavy isotope signature of dissolved Cu in seawater. The PMT enables high volume sample collection from deep waters at the terminus of the oceanic conveyor belt, along with data for particulate metals and isotope tracers of scavenging. Moreover, the relationship between labile and non-labile Cu can be studied over several distinct biomes, including high-nutrient, low chlorophyll regions and oligotrophic subtropical gyres along the PMT. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/72335
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	James Moffett.U.S. GEOTRACES PMT: Measurement of the organic complexation and chemical lability of dissolved copper using multiple techniques.2018.