DOI: 10.1002/2015GB005350
Scopus记录号: 2-s2.0-84978795854
论文题名: Enzyme-level interconversion of nitrate and nitrite in the fall mixed layer of the Antarctic Ocean
作者: Kemeny P ; C ; , Weigand M ; A ; , Zhang R ; , Carter B ; R ; , Karsh K ; L ; , Fawcett S ; E ; , Sigman D ; M
刊名: Global Biogeochemical Cycles
ISSN: 8866236
出版年: 2016
卷: 30, 期: 7 起始页码: 1069
结束页码: 1085
语种: 英语
英文关键词: antarctic
; fall
; interconversion
; nitrate
; nitrite
; seasonality
Scopus关键词: enzyme activity
; growth rate
; mixed layer
; nitrate
; nitrite
; nitrogen isotope
; oxidation
; oxygen isotope
; phytoplankton
; seasonality
; upwelling
; Southern Ocean
英文摘要: In the Southern Ocean, the nitrogen (N) isotopes of organic matter and the N and oxygen (O) isotopes of nitrate (NO3 −) have been used to investigate NO3 − assimilation and N cycling in the summertime period of phytoplankton growth, both today and in the past. However, recent studies indicate the significance of processes in other seasons for producing the annual cycle of N isotope changes. This study explores the impact of fall conditions on the 15N/14N (δ15N) and 18O/16O (δ18O) of NO3 − and nitrite (NO2 −) in the Pacific Antarctic Zone using depth profiles from late summer/fall of 2014. In the mixed layer, the δ15N and δ18O of NO3 − + NO2 − increase roughly equally, as expected for NO3 − assimilation; however, the δ15N of NO3 −-only (measured after NO2 − removal) increases more than does NO3 −-only δ18O. Differencing indicates that NO2 − has an extremely low δ15N, often < −70‰ versus air. These observations are consistent with the expression of an equilibrium N isotope effect between NO3 − and NO2 −, likely due to enzymatic NO3 −-NO2 − interconversion. Specifically, we propose reversibility of the nitrite oxidoreductase (NXR) enzyme of nitrite oxidizers that, having been entrained from the subsurface during late summer mixed layer deepening, are inhibited by light. Our interpretation suggests a role for NO3 −-NO2 − interconversion where nitrifiers are transported into environments that discourage NO2 − oxidation. This may apply to surface regions with upwelling, such as the summertime Antarctic. It may also apply to oxygen-deficient zones, where NXR-catalyzed interconversion may explain previously reported evidence of NO2 − oxidation. ©2016. 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/77839
Appears in Collections: 气候变化事实与影响
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作者单位: Department of Geosciences, Princeton University, Princeton, NJ, United States; Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, United States; College of Ocean and Earth Sciences, Xiamen University, Xiamen, China; Joint Institute for the Study of the Atmosphere and Ocean, University of Washington, Seattle, WA, United States; NOAA Pacific Marine Environmental Laboratory, Seattle, WA, United States; Antarctic Climate & Ecosystems Cooperative Research Centre, University of Tasmania, Hobart, TAS, Australia; Department of Oceanography, University of Cape Town, Rondebosch, South Africa
Recommended Citation:
Kemeny P,C,, Weigand M,et al. Enzyme-level interconversion of nitrate and nitrite in the fall mixed layer of the Antarctic Ocean[J]. Global Biogeochemical Cycles,2016-01-01,30(7)