DOI: 10.1029/2019GB006242
论文题名: Dinitrogen Fixation Across Physico-Chemical Gradients of the Eastern Tropical North Pacific Oxygen Deficient Zone
作者: Selden C.R. ; Mulholland M.R. ; Bernhardt P.W. ; Widner B. ; Macías-Tapia A. ; Ji Q. ; Jayakumar A.
刊名: Global Biogeochemical Cycles
ISSN: 0886-6236
EISSN: 1944-9224
出版年: 2019
卷: 33, 期: 9 语种: 英语
英文关键词: dissolved organic carbon
; nitrogen fixation
; oxygen
; oxygen minimum layer
; physicochemical property
; Pacific Ocean
; Pacific Ocean (North)
; Pacific Ocean (South)
; Pacific Ocean (South)
学科: aphotic
; diazotroph
; eastern tropical pacific
; nitrogen fixation
; oxygen deficient zone
; oxygen minimum zone
中文摘要: The Eastern Tropical North Pacific Ocean hosts one of the world's largest oceanic oxygen deficient zones (ODZs). Hot spots for reactive nitrogen (Nr) removal processes, ODZs generate conditions proposed to promote Nr inputs via dinitrogen (N2) fixation. In this study, we quantified N2 fixation rates by 15N tracer bioassay across oxygen, nutrient, and light gradients within and adjacent to the ODZ. Within subeuphotic oxygen-deplete waters, N2 fixation was largely undetectable; however, addition of dissolved organic carbon stimulated N2 fixation in suboxic (<20 μmol/kg O2) waters, suggesting that diazotroph communities are likely energy limited or carbon limited and able to fix N2 despite high ambient concentrations of dissolved inorganic nitrogen. Elevated rates (>9 nmol N·L−1·day−1) were also observed in suboxic waters near volcanic islands where N2 fixation was quantifiable to 3,000 m. Within the overlying euphotic waters, N2 fixation rates were highest near the continent, exceeding 500 μmol N·m−2·day−1 at one third of inshore stations. These findings support the expansion of the known range of diazotrophs to deep, cold, and dissolved inorganic nitrogen-replete waters. Additionally, this work bolsters calls for the reconsideration of ocean margins as important sources of Nr. Despite high rates at some inshore stations, regional N2 fixation appears insufficient to compensate for Nr loss locally as observed previously in the Eastern Tropical South Pacific ODZ. ©2019. The Authors. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/160106
Appears in Collections: 气候变化与战略
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作者单位: Department of Ocean, Earth & Atmospheric Science, Old Dominion University, Norfolk, VA, United States; Now at Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, United States; Institute of Oceanological Research, Autonomous University of Baja California, Ensenada, Mexico; Department of Geosciences, Princeton University, Princeton, NJ, United States; Now at Helmholtz Center for Ocean Research Kiel, Kiel, Germany
Recommended Citation:
Selden C.R.,Mulholland M.R.,Bernhardt P.W.,et al. Dinitrogen Fixation Across Physico-Chemical Gradients of the Eastern Tropical North Pacific Oxygen Deficient Zone[J]. Global Biogeochemical Cycles,2019-01-01,33(9)