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Hydrothermal (NN)-N-15-N-15 abundances constrain the origins of mantle nitrogen 期刊论文
NATURE, 2020, 580 (7803) : 367-+
作者:  Zhao, Steven;  Jang, Cholsoon;  Liu, Joyce;  Uehara, Kahealani;  Gilbert, Michael;  Izzo, Luke;  Zeng, Xianfeng;  Trefely, Sophie;  Fernandez, Sully;  Carrer, Alessandro;  Miller, Katelyn D.;  Schug, Zachary T.;  Snyder, Nathaniel W.;  Gade, Terence P.;  Titchenell, Paul M.;  Rabinowitz, Joshua D.;  Wellen, Kathryn E.
收藏  |  浏览/下载：34/0  |  提交时间：2020/05/13

Nitrogen is the main constituent of the Earth'  s atmosphere, but its provenance in the Earth'  s mantle remains uncertain. The relative contribution of primordial nitrogen inherited during the Earth'  s accretion versus that subducted from the Earth'  s surface is unclear(1-6). Here we show that the mantle may have retained remnants of such primordial nitrogen. We use the rare (NN)-N-15-N-15 isotopologue of N-2 as a new tracer of air contamination in volcanic gas effusions. By constraining air contamination in gases from Iceland, Eifel (Germany) and Yellowstone (USA), we derive estimates of mantle delta N-15 (the fractional difference in N-15/N-14 from air), N-2/Ar-36 and N-2/He-3. Our results show that negative delta N-15 values observed in gases, previously regarded as indicating a mantle origin for nitrogen(7-10), in fact represent dominantly air-derived N-2 that experienced N-15/N-14 fractionation in hydrothermal systems. Using two-component mixing models to correct for this effect, the (NN)-N-15-N-15 data allow extrapolations that characterize mantle endmember delta N-15, N-2/Ar-36 and N-2/He-3 values. We show that the Eifel region has slightly increased delta N-15 and N-2/Ar-36 values relative to estimates for the convective mantle provided by mid-ocean-ridge basalts(11), consistent with subducted nitrogen being added to the mantle source. In contrast, we find that whereas the Yellowstone plume has delta N-15 values substantially greater than that of the convective mantle, resembling surface components(12-15), its N-2/Ar-36 and N-2/He-3 ratios are indistinguishable from those of the convective mantle. This observation raises the possibility that the plume hosts a primordial component. We provide a test of the subduction hypothesis with a two-box model, describing the evolution of mantle and surface nitrogen through geological time. We show that the effect of subduction on the deep nitrogen cycle may be less important than has been suggested by previous investigations. We propose instead that high mid-ocean-ridge basalt and plume delta N-15 values may both be dominantly primordial features.


  
Can We Detect Changes in Amazon Forest Structure Using Measurements of the Isotopic Composition of Precipitation? 期刊论文
GEOPHYSICAL RESEARCH LETTERS, 2019
作者:  Pattnayak, K. C.;  Tindall, J. C.;  Brienen, R. J. W.;  Barichivich, J.;  Gloor, E.
收藏  |  浏览/下载：22/0  |  提交时间：2020/02/17
precipitation oxygen isotope-ratios  land derived precipitation tracer  Ocean derived precipitation tracer  Rayleigh distillation  ocean-sourced precipitation  recycled precipitation  
Using Short-Term CO/CO2 Ratios to Assess Air Mass Differences Over the Korean Peninsula During KORUS-AQ 期刊论文
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 2019
作者:  Halliday, H. S.;  DiGangi, J. P.;  Choi, Y.;  Diskin, G. S.;  Pusede, S. E.;  Rana, M.;  Nowak, J. B.;  Knote, C.;  Ren, X.;  He, H.;  Dickerson, R. R.;  Li, Z.
收藏  |  浏览/下载：26/0  |  提交时间：2019/11/27
carbon monoxide  carbon dioxide  CO  CO2 ratios  Korean air quality  air mass characterization  tracer ratios