Seasonal variation of N2O emissions in France inferred from atmospheric N2O and 222Rn measurements

• Published in: Journal of Geophysical Research: Atmospheres 2012-07, Vol.117 (D14), p.n/a
• Main Authors: Lopez, M., Schmidt, M., Yver, C., Messager, C., Worthy, D., Kazan, V., Ramonet, M., Bousquet, P., Ciais, P.
• Format: Article
• Language: English
• Subjects: Earth sciences; Earth, ocean, space; emission; Exact sciences and technology; nitrous oxide; radon
• ISSN: 0148-0227; 2156-2202
• DOI: 10.1029/2012JD017703

Nitrous oxide (N2O) concentrations and 222Rn activities are measured semi‐continuously at three stations in France: Gif‐sur‐Yvette (a semi‐urban station near Paris), Trainou tower (a rural station) and Puy‐de‐Dôme (a mountain site). From 2002 to 2011, we have found a mean rate of N2O increase of 0.7 pbb a−1. The analysis of the mean diurnal N2O and 222Rn cycles shows maximum variabilities at the semi‐urban site of Gif‐sur‐Yvette (0.96 ppb for N2O and 2 Bq m−3 for 222Rn) compared to the rural site of Trainou tower (0.32 ppb for N2O and 1.3 Bq m−3 for 222Rn). The use of 222Rn as a tracer for vertical mixing and atmospheric transport, combined with the semi‐continuous N2O measurements, allows estimation of N2O emissions by applying the Radon‐Tracer‐Method. Mean N2O emissions values between 0.34 ± 0.12 and 0.51 ± 0.18 g(N2O) m−2 a−1 and 0.52 ± 0.18 g(N2O) m−2 a−1were estimated in the catchment area of Gif‐sur‐Yvette and Trainou, respectively. The mean annual N2O fluxes at Gif‐sur‐Yvette station correlate well with annual precipitation. A 25% increase in precipitation corresponds to a 32% increase in N2O flux. The N2O fluxes calculated with the Radon‐Tracer‐Method show a seasonal cycle, which indicates a strong contribution from the agricultural source, with the application of fertilizers in the early spring inducing a strong increase in N2O emissions. Finally, the results of the Radon‐Tracer‐Method agree well with the national and global emission inventories, accounting for the uncertainties of both methods. Key Points Mean seasonal cycle of N2O shows the importance of the agricultural source Annual nitrous oxide emissions are correlated with annual precipitation Comparison between atmospheric approach and inventories agree well