δ15N of nitric oxide produced under aerobic or anaerobic conditions from seven soils and their associated N isotope fractionations
我组成员在 Journal of Geophysical Research Biogeosciences 上发表文章：Chenxia Su, Ronghua Kang, Weixing Zhu, Wentao Huang, Linlin Song, Ang Wang, Dongwei Liu, Zhi Quan, Feifei Zhu, Pingqing Fu, Yunting Fang. δ15N of nitric oxide produced under aerobic or anaerobic conditions from seven soils and their associated N isotope fractionations [J]. Journal of Geophysical Research Biogeosciences, 2020.
文章链接：https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020JG005705
Measuring the nitrogen isotope compositions (δ15N) of nitric oxide (NO) from different sources helps to quantify the relative contributions of atmospheric NOx. Soil is one of the most important sources of atmospheric NOx, but only limited measurements on the δ15N of soil-emitted NO exist, hampering our ability to partition sources to air pollution. Here we conducted soil incubations to measure the δ15N-NO under defined aerobic or anaerobic conditions, favoring either nitrification or denitrification. Soils were collected from seven sites spanning three ecosystems in northern China (two agricultural, two forest, and three grassland sites). We found that the δ15N-NO and their associated N isotope fractionations were significantly different between anaerobic and aerobic conditions in seven soils. Under aerobic condition, the δ15N-NO ranged from -62‰ to -50‰ (averaged -56 ± 4‰), being significantly more negative (by 23‰) than those under anaerobic condition (-45‰ to -23‰, averaged-33 ± 7‰). The apparent N isotope fractionation for NO production under aerobic condition (15εaerobic = 61 ± 3‰) was significantly higher (by 26‰) than under anaerobic condition (15εanaerobic = 35 ± 6‰), with a small variability among ecosystem types. Our study demonstrates that the δ15N-NO from different soils are very different from fuel combustions (mainly from 0‰ to +20‰), supporting that measuring 15N is a useful tool to partition the contributions of soil NO to atmospheric NOx. Our results also imply δ15N-NO produced by nitrification and denitrification distinctly different, as these two processes are dominant processes producing NO under aerobic and anaerobic conditions, respectively.
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