一氧化二氮
反硝化
富营养化
环境科学
优势(遗传学)
硝化作用
环境化学
δ18O
δ15N
污染
氮气
水文学(农业)
δ13C
稳定同位素比值
化学
生态学
营养物
地质学
生物
物理
有机化学
基因
岩土工程
量子力学
生物化学
作者
Qingqian Li,Fang Wang,Qibiao Yu,Weijin Yan,Xinyan Li,Shucong Lv
标识
DOI:10.1016/j.envpol.2019.113212
摘要
In recent decades, most lakes in Eastern China have suffered unprecedented nitrogen pollution, making them potential "hotspots" for N2O production and emission. Understanding the mechanisms of N2O production and quantifying emissions in these lakes is essential for assessing regional and global N2O budgets and for mitigating N2O emissions. Here, we measure isotopic compositions (δ15N-N2O and δ18O-N2O) and site preference (SP) of dissolved N2O in an attempt to differentiate the relative contribution of N2O production processes in the shallow, eutrophic Chaohu Lake, Eastern China. Our results show that the bulk isotope ratios for δ15N-N2O, δ18O-N2O, and SP were 5.8 ± 3.9‰, 29.3 ± 13.4‰, and 18.6 ± 3.2‰, respectively. More than 76.8% of the dissolved N2O was produced via microbial processes. Findings suggest that dissolved N2O is primarily produced via nitrification (between 27.3% and 48.0%) and denitrification (between 31.9% and 49.5%). In addition, isotopic data exhibit significant N2O consumption during denitrification. We estimate the average N2O emission rate (27.5 ± 26.0 μg N m−2 h−1), which is higher than that from rivers in the Changjiang River network (CRN). We scaled-up the regional N2O emission (from 1.98 Gg N yr−1 to 4.58 Gg N yr−1) using a N2O emission factor (0.51 ± 0.63%) for shallow lakes in the middle and lower region of the CRN. We suggest that beneficial circumstances for promoting complete denitrification may be helpful for reducing N2O production and emissions in fresh surface waters.
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