Aerosol fluxes and particle growth above managed grassland

Nemitz, E.; Dorsey, J.R.; Flynn, M.J.; Gallagher, M.W.; Hensen, A.; Erisman, J.-W.; Owen, S.M.; Dammgen, U.; Sutton, M.A.. 2009 Aerosol fluxes and particle growth above managed grassland. Biogeosciences Discussions, 6 (1). 341-389.

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Particle deposition velocities (11–3000nm diameter) measured above grassland by eddy covariance during the EU GRAMINAE experiment in June 2000 averaged 0.24 and 0.03mms−1 to long (0.75 m) and short (0.07 m) grass, respectively. After fertilisation with 108 kgNha−1 5 as calcium ammonium nitrate, sustained apparent upward fluxes of particles were observed. Analysis of concentrations and fluxes of potential precursor gases, including NH3, HNO3, HCl and selected VOCs, shows that condensation of HNO3 and NH3 on the surface of existing particles is responsible for this effect. A novel approach is developed to derive particle growth rates at the field scale, 10 from a combination of measurements of vertical fluxes and particle size-distributions. For the first 9 days after fertilization, growth rates of 11nm particles of 3.5nmhr−1 and 0.89nmhr−1 were derived for day and night-time conditions, respectively. This implies total NH4NO3 production rates of 1.1 and 0.44 μgm−3 h−1, respectively. The effect translates into a small error in measured ammonia fluxes (0.06% day, 0.56% night) and a larger error in NH+4 and NO− 3 15 aerosol fluxes of 3.6% and 10%, respectively. By converting rapidly exchanged NH3 and HNO3 into slowly depositing NH4NO3, the reaction modifies the total N budget, though this effect is small (<1% for the 10 days following fertilization), as NH3 emission dominates the net flux. It is estimated that 3.8% of the fertilizer N was volatilised as NH3, of which 0.05% re-condensed to form 20 NH4NO3 particles within the lowest 2m of the surface layer. This surface induced process would at least scale up to a global NH4NO3 formation of ca. 0.21 ktNyr−1 from NH4NO3 fertilisers and potentially 45 ktNyr−1

Item Type: Publication - Article
Programmes: CEH Programmes pre-2009 publications > Biogeochemistry > BG01 Measuring and modelling trace gas, aerosol and carbon > BG01.1 UK nitrogen and sulphur compounds
CEH Programmes pre-2009 publications > Biogeochemistry > BG01 Measuring and modelling trace gas, aerosol and carbon > BG01.3 Nitroeurope NEU advanced flux network, fluxes pools and budgets
CEH Sections: Billett (to November 2013)
Additional Information. Not used in RCUK Gateway to Research.: Open Access Journal. The full text of this paper is available from the journal website.
NORA Subject Terms: Atmospheric Sciences
Date made live: 01 Jun 2009 09:33

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