气候变化领域集成服务门户(CCPortal): The Dual Isotopic Composition of Nitrate in the Gulf of Mexico and Florida Straits

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DOI	10.1029/2020JC016047
	The Dual Isotopic Composition of Nitrate in the Gulf of Mexico and Florida Straits
	Howe S.; Miranda C.; Hayes C.T.; Letscher R.T.; Knapp A.N.
发表日期	2020
ISSN	21699275
卷号	125 期号:9
英文摘要	The Gulf of Mexico receives considerable riverine nutrient inputs that contribute to eutrophication of northern shelf waters. However, it is unclear whether a significant fraction of these riverine nutrients delivered to the Gulf of Mexico are subsequently exported from the Gulf, potentially influencing the chemistry of the North Atlantic. Here, we report the first dual isotopic composition (“δ15N” and “δ18O”) measurements of nitrate (NO3−) from three profiles collected in different years in the Gulf of Mexico, as well as a new profile from the Florida Straits. We compare these new measurements with prior measurements from the North and South Atlantic, as well as with the magnitude of riverine and other nitrogen fluxes to the Gulf of Mexico. We find that in the upper thermocline, NO3− δ15N measurements from the Gulf of Mexico are intermediate between prior measurements in the Sargasso Sea (lower in NO3− δ15N), and those from the South Atlantic (higher in NO3− δ15N), but are indistinguishable from Florida Straits and Sargasso Sea profiles on deeper isopycnal surfaces. There is little evidence for riverine NO3− influencing the isotopic composition of NO3− exported from the Gulf of Mexico, which, based on its δ15N, would be expected to raise the δ15N of shallow NO3−. Lesser nitrogen fluxes are too small to significantly influence the isotopic composition of water column NO3− in the Gulf of Mexico. These results are consistent with recent modeling work suggesting that the majority of riverine nutrients are retained in the nearshore region. ©2020. American Geophysical Union. All Rights Reserved.
英文关键词	Gulf of Mexico; Mississippi River; nitrate; nitrate isotopes
语种	英语
来源期刊	Journal of Geophysical Research: Oceans
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/186688
作者单位	Earth, Ocean, and Atmospheric Science Department, Florida State University, Tallahassee, FL, United States; School of Ocean Science and Engineering, University of Southern Mississippi, Stennis Space Center, MS, United States; Earth Sciences and Ocean Process Analysis Laboratory, University of New Hampshire, Durham, NH, United States
推荐引用方式 GB/T 7714	Howe S.,Miranda C.,Hayes C.T.,et al. The Dual Isotopic Composition of Nitrate in the Gulf of Mexico and Florida Straits[J],2020,125(9).
APA	Howe S.,Miranda C.,Hayes C.T.,Letscher R.T.,&Knapp A.N..(2020).The Dual Isotopic Composition of Nitrate in the Gulf of Mexico and Florida Straits.Journal of Geophysical Research: Oceans,125(9).
MLA	Howe S.,et al."The Dual Isotopic Composition of Nitrate in the Gulf of Mexico and Florida Straits".Journal of Geophysical Research: Oceans 125.9(2020).