DOI: 10.1029/2019GB006279
论文题名: An Investigation Into the Origin of Nitrate in Arctic Sea Ice
作者: Clark S.C. ; Granger J. ; Mastorakis A. ; Aguilar-Islas A. ; Hastings M.G.
刊名: Global Biogeochemical Cycles
ISSN: 0886-6236
EISSN: 1944-9224
出版年: 2020
卷: 34, 期: 2 语种: 英语
英文关键词: ammonium
; atmospheric deposition
; concentration (composition)
; isotopic composition
; melting
; nitrate
; nitrogen
; Northern Hemisphere
; primary production
; provenance
; sea ice
; seawater
; Arctic Ocean
中文摘要: 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. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/160062
Appears in Collections: 气候变化与战略
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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
Recommended Citation:
Clark S.C.,Granger J.,Mastorakis A.,et al. An Investigation Into the Origin of Nitrate in Arctic Sea Ice[J]. Global Biogeochemical Cycles,2020-01-01,34(2)