Key Laboratory of Mountain Surface Processes and Ecological Regulation, Chinese Academy of Sciences, Chengdu 610041, China; Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China; University of Chinese Academy of Sciences, Beijing 100049, China; Institute for Agro-Environmental Sciences, National Agriculture and Food Research Organization, Tsukuba 305-8604, Japan.
Institute for Agro-Environmental Sciences, National Agriculture and Food Research Organization, Tsukuba 305-8604, Japan.
Environ Pollut. 2018 Nov;242(Pt A):480-491. doi: 10.1016/j.envpol.2018.07.018. Epub 2018 Jul 7.
Nitrogen (N)-enriched leaching water may act as a source of indirect NO emission when it is discharged to agricultural drainage ditches. In this study, indirect NO 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 NO emissions contributing an inter-annual mean flux of 6.56 ± 1.12 μg N m h and a mean indirect NO emission factor (EF) value of 0.03 ± 0.003%. The mean EF value from literature review was 0.51%, which was higher than the default EF value (0.25%) proposed by the Intergovernmental Panel on Climate Change (IPCC) in 2006. Our study demonstrated that, more in situ observations of NO emissions as regards N leaching are required, to account for the large variation in EF values and to improve the accuracy and confidence of the default EF value. Indirect NO emissions varied with season, higher emissions occurred in summer and autumn. These seasonal variations were related to drainage water NO-N concentration, temperature, and precipitation. Our results showed that intensive precipitation increased NO-N concentrations and NO emissions, and when combined with warmer water temperatures, these may have increased the denitrification rate that led to the higher summer and autumn NO emissions in the studied agricultural drainage ditch.
富含氮 (N) 的淋溶水排放到农业排水沟渠时，可能成为间接 NO 排放的来源。本研究采用静态箱-气相色谱法，于 2012-2015 年期间，对中国西南部四川盆地中部主要接收侧向水流的农业排水沟渠进行了间接 NO 排放测量。结果表明，该排水沟渠是间接 NO 排放的一个来源，其年平均通量为 6.56±1.12μg N m h，间接 NO 排放因子 (EF) 值的平均值为 0.03±0.003%。文献综述中的平均 EF 值为 0.51%，高于 2006 年政府间气候变化专门委员会 (IPCC) 提出的默认 EF 值 (0.25%)。本研究表明，需要更多关于氮淋溶的原位 NO 排放观测，以解释 EF 值的较大变化，并提高默认 EF 值的准确性和置信度。间接 NO 排放随季节而变化，夏季和秋季排放量较高。这些季节性变化与排水水中的 NO3-N 浓度、温度和降水有关。研究结果表明，强降水增加了 NO3-N 浓度和 NO 排放，而与更温暖的水温相结合时，可能会增加反硝化速率，从而导致所研究的农业排水沟渠夏季和秋季的 NO 排放量较高。
