An automated dynamic chamber system for exchange flux measurement of reactive nitrogen oxides (HONO and NOX) in farmland ecosystems of the Huaihe River Basin, China

Ke Tang; Min Qin; Wu Fang; Jun Duan; Fanhao Meng; Kaidi Ye; Helu Zhang; Pinhua Xie; Jianguo Liu; Wenqing Liu; Yan Feng; Yong Huang; Ting Ni

doi:10.1016/j.scitotenv.2020.140867

An automated dynamic chamber system for exchange flux measurement of reactive nitrogen oxides (HONO and NO_X) in farmland ecosystems of the Huaihe River Basin, China

Sci Total Environ. 2020 Nov 25:745:140867. doi: 10.1016/j.scitotenv.2020.140867. Epub 2020 Jul 11.

Authors

Ke Tang¹, Min Qin², Wu Fang³, Jun Duan⁴, Fanhao Meng¹, Kaidi Ye¹, Helu Zhang¹, Pinhua Xie⁵, Jianguo Liu⁵, Wenqing Liu⁵, Yan Feng⁶, Yong Huang⁶, Ting Ni⁶

Affiliations

¹ Key Laboratory of Environment Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China; University of Science and Technology of China, Hefei 230027, China.
² Key Laboratory of Environment Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China. Electronic address: mqin@aiofm.ac.cn.
³ Key Laboratory of Environment Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China. Electronic address: wfang@aiofm.ac.cn.
⁴ Key Laboratory of Environment Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China.
⁵ Key Laboratory of Environment Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China; University of Science and Technology of China, Hefei 230027, China; CAS Center for Excellence in Urban Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
⁶ Anhui Institute of Meteorological Sciences, Anhui Province Key Laboratory of Atmospheric Science and Satellite Remote Sensing, Hefei 230031, China; Shouxian National Climatology Observatory, Huaihe River Basin Typical Farm Eco-meteorological Experiment Field of CMA, Shouxian 232200, China.

PMID: 32738680
DOI: 10.1016/j.scitotenv.2020.140867

Abstract

An automated dynamic chamber system was first developed to simultaneously measure the HONO flux and NOx flux. The new dynamic chamber system was applied to field observation, and the HONO and NO_X exchange flux of farmland in the Huaihe River Basin was obtained for the first time. The performance of the dynamic chamber system was verified in the field. In the field observation, the diurnal variations of the HONO fluxes and NO fluxes before and after a rainfall event exhibited two different trends. Before the rainfall and in the latter stage after the rainfall, the maxima of the HONO fluxes and NO fluxes occurred in the morning, then decreased gradually. However, during the early stage after the rainfall, the HONO fluxes and NO fluxes gradually increased in the morning and reached their maximum values in the afternoon. During the measurement period, the maximum HONO flux was 7.69 ng N m^-2 s^-1 and the maximum NO flux was 34.52 ng N m^-2 s^-1. There was no significant correlation between HONO flux and temperature before the rainfall and in the latter stage after the rainfall period, although the correlation coefficient (R) between HONO flux and temperature reached 0.78 in the early stage after the rainfall period, and the R between NO flux and HONO flux reached more than 0.6 before and after rainfall periods. The HONO flux of fresh soil samples were the same order of magnitude as that of field observations. The field results indicate that soil emissions are an important source of atmospheric HONO during the crop growth stage. Negative NO₂ fluxes were found in most observation periods, and there were significant negative linear correlations between NO₂ fluxes and atmospheric NO₂ concentrations. The R between ambient NO₂ concentration and NO₂ flux was 0.79, and the compensation point of NO₂ was 5 ppbv.

Keywords: Agricultural soil; Automated dynamic chamber; HONO flux; NO(X) flux.