Indirect N2O emissions with seasonal variations from an agricultural drainage ditch mainly receiving interflow water
Indirect N2O emissions with seasonal variations from an agricultural drainage ditch mainly receiving interflow water
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主要接收混流水的农业排水沟随季节变化的间接 N2O 排放
DOI：
10.1016/j.envpol.2018.07.018
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发表时间：
2018
影响因子：
8.9
通讯作者：
Shen Xi
中科院分区：
文献类型：
--
作者：
Tian Linlin;Akiyama Hiroko;Zhu Bo;Shen Xi
富氮浸出水排入农业排水沟渠后，可能成为N2O的间接排放源。本研究利用静态室气相色谱法测量了2012-2015年四川盆地中部一条主要接收中流水的农业排水沟的间接N2O排放。研究结果表明，沟渠是N2O间接排放源，其年际平均通量为6.56 ± 1.12 μg N m−2h−1，平均间接排放因子（EF5g）为0.03 ± 0.003%。从文献综述中得到的ef5g平均值为0.51%，高于2006年政府间气候变化专门委员会（IPCC）提出的缺省值0.25%。我们的研究表明，为了解释ef5g值的巨大变化，并提高默认ef5g值的准确性和置信度，需要对N浸出方面的N2O排放进行更多的现场观测。间接N2O排放量随季节变化，夏季和秋季排放量较高。这些季节变化与排水NO3−-N浓度、温度和降水有关。结果表明，强降水增加了NO3−-N浓度和N2O排放，并且当水温升高时，这些可能增加了反硝化速率，导致所研究的农业排水沟夏季和秋季N2O排放量增加。
Nitrogen (N)-enriched leaching water may act as a source of indirect N2O emission when it is discharged to agricultural drainage ditches. In this study, indirect N2O emissions from an agricultural drainage ditch mainly receiving interflow water were measured using the static chamber-gas chromatography technique during 2012–2015 in the central Sichuan Basin in southwestern China. We found the drainage ditch was a source of indirect N2O emissions contributing an inter-annual mean flux of 6.56 ± 1.12 μg N m−2h−1and a mean indirect N2O emission factor (EF5g) value of 0.03 ± 0.003%. The mean EF5gvalue from literature review was 0.51%, which was higher than the default EF5gvalue (0.25%) proposed by the Intergovernmental Panel on Climate Change (IPCC) in 2006. Our study demonstrated that, morein situobservations of N2O emissions as regards N leaching are required, to account for the large variation in EF5gvalues and to improve the accuracy and confidence of the default EF5gvalue. Indirect N2O emissions varied with season, higher emissions occurred in summer and autumn. These seasonal variations were related to drainage water NO3−-N concentration, temperature, and precipitation. Our results showed that intensive precipitation increased NO3−-N concentrations and N2O emissions, and when combined with warmer water temperatures, these may have increased the denitrification rate that led to the higher summer and autumn N2O emissions in the studied agricultural drainage ditch.