College of Resources, Sichuan Agricultural University, Chengdu, 611130, People's Republic of China.
College of Environmental Science, Sichuan Agricultural University, Chengdu, 611130, People's Republic of China.
Environ Sci Pollut Res Int. 2019 Jun;26(16):16596-16605. doi: 10.1007/s11356-019-04992-8. Epub 2019 Apr 15.
Multi-level ditch area is a major component of the hydrographic net of plain area, China. Given the high concentration of nitrogen (N) in the surface water and vigorous biogeochemical interactions, ditch is likely to be the hot spots of NO emission. However, NO emission flux and emission factor (EF) of multi-level ditches have not been determined. To address this knowledge gap, a 1-year field work in three ditches with different levels in Chengdu Plain was conducted. It is found that the annual flux of NO emission and EF was higher in the lateral (0.0020 and 83.94 μg m h) and field ditches (0.0019 and 110.75 μg m h) than in the branch ditch (0.0016 and 46.38 μg m h, P < 0.05). It is found that parameters of groundwater level, discharge, precipitation, and NH were the primary factors, and these parameters can model the NO flux well. Furthermore, the content of NH in the surface water of ditches presented better correlation with the emission of NO than the content of NO. Therefore, controlling NH emission and lessening fertilizer usage in summer may be key solutions for indirect reduction of NO in Chengdu Plain.
多级沟渠区域是中国平原地区水系的主要组成部分。鉴于地表水含氮量高和强烈的生物地球化学相互作用，沟渠很可能是氮氧化物排放的热点区域。然而，多级沟渠的氮氧化物排放通量和排放因子（EF）尚未确定。为了解决这一知识空白，在成都平原的三条不同级别的沟渠中进行了为期 1 年的野外工作。研究发现，侧向沟渠（0.0020 和 83.94μg m h）和田间沟渠（0.0019 和 110.75μg m h）的氮氧化物排放年通量和 EF 均高于支沟（0.0016 和 46.38μg m h，P<0.05）。研究发现，地下水位、流量、降水和 NH 参数是主要因素，这些参数可以很好地模拟氮氧化物通量。此外，沟渠表面水中的 NH 含量与氮氧化物的排放呈更好的相关性，而不是氮氧化物的含量。因此，控制 NH 的排放和减少夏季肥料的使用可能是减少成都平原间接氮氧化物的关键措施。
