Isotopic constraints confirm the significant role of microbial nitrogen oxides emissions from the land and ocean environment  

作　　者：Wei Song Xue-Yan Liu Benjamin Z.Houlton Cong-Qiang Liu 

机构地区：[1]School of Earth System Science,Tianjin University,Tianjin 300072,China [2]Department of Global Development and Department of Ecology and Evolutionary Biology,Cornell University,Ithaca,NY 14850,USA

出　　处：《National Science Review》2022年第9期181-189,共9页国家科学评论（英文版）

基　　金：supported by the National Natural Science Foundation of China(42125301,41730855 and 42073005);the Coordinated Research Project of IAEA(F32008)。

摘　　要：Nitrogen oxides(NO_(x),the sum of nitric oxide(NO)and N dioxide(NO_(2)))emissions and deposition have increased markedly over the past several decades,resulting in many adverse outcomes in both terrestrial and oceanic environments.However,because the microbial NO_(x) emissions have been substantially underestimated on the land and unconstrained in the ocean,the global microbial NO_(x) emissions and their importance relative to the known fossil-fuel NO_(x) emissions remain unclear.Here we complied data on stable N isotopes of nitrate in atmospheric particulates over the land and ocean to ground-truth estimates of NO_(x) emissions worldwide.By considering the N isotope effect of NO_(x) transformations to particulate nitrate combined with dominant NO_(x) emissions in the land(coal combustion,oil combustion,biomass burning and microbial N cycle)and ocean(oil combustion,microbial N cycle),we demonstrated that microbial NO_(x) emissions account for 24±4%,58±3%and 31±12%in the land,ocean and global environment,respectively.Corresponding amounts of microbial NO_(x) emissions in the land(13.6±4.7 Tg N yr^(-1)),ocean(8.8±1.5 Tg N yr^(-1))and globe(22.5±4.7 Tg N yr^(-1))are about 0.5,1.4 and 0.6 times on average those of fossil-fuel NO_(x) emissions in these sectors.Our findings provide empirical constraints on model predictions,revealing significant contributions of the microbial N cycle to regional NO_(x) emissions into the atmospheric system,which is critical information for mitigating strategies,budgeting N deposition and evaluating the effects of atmospheric NO_(x) loading on the world.

关 键 词：nitrogen isotopes NITRATE NO_(x)emission nitrogen deposition microbial N cycle 

分 类 号：P736.44[天文地球—海洋地质]