Indirect N 2 O emissions with seasonal variations from an agricultural drainage ditch mainly receiving interflow water

• Published in: Environmental pollution (1987) 2018-07, Vol.242 (Pt A), p.480
• Main Authors: Tian, Linlin, Akiyama, Hiroko, Zhu, Bo, Shen, Xi
• Format: Article
• Language: English
• ISSN: 1873-6424
• DOI: 10.1016/j.envpol.2018.07.018

Nitrogen (N)-enriched leaching water may act as a source of indirect N O emission when it is discharged to agricultural drainage ditches. In this study, indirect N O 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 N O emissions contributing an inter-annual mean flux of 6.56 ± 1.12 μg N m  h and a mean indirect N O 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 N O 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 N O 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 N O emissions, and when combined with warmer water temperatures, these may have increased the denitrification rate that led to the higher summer and autumn N O emissions in the studied agricultural drainage ditch.