Applicability of an eddy covariance system based on a close-path quantum cascade laser spectrometer for measuring nitrous oxide fluxes from subtropical vegetable fields  

作　　者：WANG Dong WANG Kai Eugenio DíAZ-PINS ZHENG Xunhua Klaus BUTTERBACH-BAHL 

机构地区：[1]State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry,Institute of Atmospheric Physics,Chinese Academy of Sciences (IAP-CAS) [2]College of Earth Science,University of Chinese Academy of Sciences [3]Institute of Meteorology and Climate Research,Atmospheric Environmental Research,Karlsruhe Institute of Technology

出　　处：《Atmospheric and Oceanic Science Letters》2016年第5期381-387,共7页大气和海洋科学快报（英文版）

基　　金：supported from the Ministry of Science and Technology of China[grant number 2012CB417106];the Chinese Academy of Sciences[grant number XDA05020100];the German Science Foundation[contract number BU1173/12-1];the National Natural Science Foundation of China[grant numbers41405137 and 41321064]

摘　　要：The soil of subtropical vegetable fields is an important source of the atmospheric greenhouse gas nitrous oxide（N2O）. In a field study in subtropical China, the authors used an eddy covariance（EC）system based on a close-path quantum cascade laser（QCL） spectrometer to measure N2O fluxes from a vegetable field. During the experimental period from 9 October 2014 to 18 February 2015,the observed half-hourly N2O fluxes ranged from.10.7 to 1077.4 μg N m^-2h^-1, with a mean value of99.3 μg N m^-2h^-1. The detection limit（95% confidence level） of the EC system for half-hourly fluxes was estimated at 18.5 μg N m^-2h^-1, i.e. smaller than 97.5% of all measured fluxes, and within the range of the lower limit of reported N2O emissions from subtropical vegetable fields. The random uncertainties in the half-hourly fluxes were estimated at 60% on average, of which 62% was due to stochastic variations caused by turbulence and 38% by instrumental noise. The flux systematic uncertainties were estimated at.18% on average, mainly due to the spectral attenuation; however,this negative bias had already been corrected for by calculating half-hourly fluxes. In conclusion,the close-path QCL-based EC technique is capable of measuring the N2O fluxes from the subtropical vegetable fields of China with high reliability and accuracy.亚热带蔬菜地是氧化亚氮(N_2O)的重要排放源,本研究首次采用基于闭路量子级联激光吸收光谱仪的涡动相关(QCLAS-EC)法观测亚热带蔬菜地秋冬季非施肥阶段的N_2O排放通量,以评估QCLAS-EC法测量亚热带蔬菜地N_2O通量的适用性。结果表明,QCLAS-EC观测系统在野外条件下能长期稳定运行,可观测到N_2O排放的季节变化趋势,其检测限为18.5μg N m^(-2) h^(-1)(95%置信水平),试验期间获得的97.5%的N_2O通量大于此检测限,表明QCLAS-EC观测系统可有效并准确测量亚热带蔬菜地的N_2O排放通量,仪器本身的灵敏度不是通量检测的限制因素。

关 键 词：Nitrous oxide flux quantum cascade laser eddy covariance subtropical vegetable field 

分 类 号：S63[农业科学—蔬菜学] S181[农业科学—园艺学]