气候变化领域集成服务门户(CCPortal): An Investigation Into the Origin of Nitrate in Arctic Sea Ice

CCPortal

DOI	10.1029/2019GB006279
	An Investigation Into the Origin of Nitrate in Arctic Sea Ice
	Clark S.C.; Granger J.; Mastorakis A.; Aguilar-Islas A.; Hastings M.G.
发表日期	2020
ISSN	0886-6236
EISSN	1944-9224
卷号	34 期号:2
英文摘要	Atmospheric deposition has been suggested to be an important source of reactive nitrogen stored in Northern Hemisphere land-fast ice, in contrast to Antarctic sea ice, where bulk nutrients originate predominantly from underlying seawater. A paucity of sea ice studies in the open Arctic Ocean limits our understanding of the potential for melting ice to contribute to primary production in N-deplete waters of the Arctic. As part of the U.S. western Arctic GEOTRACES 2015 expedition, samples of pack ice, overlying snow, atmospheric aerosols, and underlying seawater were collected between 82°N and 89°N. To identify the provenance of N in sea ice, we measured a suite of tracers including the isotopic composition of nitrate, ammonium, water, and particulate N. Relatively low concentrations of nitrate and ammonium were detected in sea ice (0.1–8.2 and 0.6–1.2 μmol L−1, respectively), and in atmospheric samples (1.1–3.7 and 0.8–1.2 μmol L−1, respectively). Atmospheric nitrate in snow had characteristically high Δ17O and δ18O (Δ17ONO3 = δ17O − 0.52 × δ18O = 27.1–33.5‰ versus Vienna Standard Mean Ocean Water (VSMOW); δ18ONO3 = 70.8–87.8‰), and low δ15NNO3 (−5.9–2‰ versus N2). In contrast to the atmospheric samples, the sea ice δ15NNO3 was typically higher (−0.3–15.0‰) and the δ17ONO3 and δ18ONO3 much lower (Δ17ONO3 = 0–12.4‰; δ18ONO3 = 23.3–67.5‰). The presence of Δ17ONO3 in the sea ice indicated that 0–40% of the nitrate is sourced from the atmosphere, while the majority of the nitrate is non-atmospheric (Δ17ONO3 = 0‰). Based upon concentration, isotopic observations, and dynamic box modeling with atmospheric deposition and biological processes, we find that the majority of nitrate can be explained by in-situ biological nitrate production. ©2020. American Geophysical Union. All Rights Reserved.
语种	英语
scopus关键词	ammonium; atmospheric deposition; concentration (composition); isotopic composition; melting; nitrate; nitrogen; Northern Hemisphere; primary production; provenance; sea ice; seawater; Arctic Ocean
来源期刊	Global Biogeochemical Cycles
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/129667
作者单位	Department of Earth, Environmental and Planetary Sciences and Institute at Brown for Environment and Society, Brown University, Providence, RI, United States; Department of Marine Sciences, University of Connecticut, Groton, CT, United States; Department of Chemistry, Brown University, Providence, RI, United States; College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK, United States
推荐引用方式 GB/T 7714	Clark S.C.,Granger J.,Mastorakis A.,et al. An Investigation Into the Origin of Nitrate in Arctic Sea Ice[J],2020,34(2).
APA	Clark S.C.,Granger J.,Mastorakis A.,Aguilar-Islas A.,&Hastings M.G..(2020).An Investigation Into the Origin of Nitrate in Arctic Sea Ice.Global Biogeochemical Cycles,34(2).
MLA	Clark S.C.,et al."An Investigation Into the Origin of Nitrate in Arctic Sea Ice".Global Biogeochemical Cycles 34.2(2020).