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Titel:
Scientific basis for an integrated nitrogen approach
 
Auteur(s):
 
Gepubliceerd door: Publicatie datum:
ECN 1-10-1999
 
ECN publicatienummer: Publicatie type:
ECN-RX--99-033 Artikel wetenschap tijdschrift
 
Aantal pagina's:
18  

Gepubliceerd in: Paper presented at the 10th Nitrogen workshop in Copenhagen, 23-26 August 1999. - Submitted to Plant and Soil (), , , Vol., p.-.

Samenvatting:
During the past two years it became clear that the measures to reduceammonia emissions in the Netherlands were less successful than anticipated. The difference between the estimated emission levels and those indicated by atmospheric measurements is called the 'ammonia gap'. Several hypotheses were published about the causes of this effect, two of which are addressed in this paper: (1) the role of sulphur emissions regulating ambient NH3 concentrations through co-deposition; and (2) long-term ammonia emissions after slurry injection. lt was found that throughfall measurements of ammonium cannot be used as an indicator for changes in NH3 emissions. The throughfall deposition of NH4 is in close equilibrium to sulphate and nitrate and is thus regulated by the equilibrium of ambient NH3 and NH4 in wet deposition and canopy water layers. When sulphur emissions decrease, the amount of available sulphate decreases, which imposes a limit on the deposition of ammonium sulphate. Long-term emissions of NH3 after application of manure were monitored using a new technique which continuously measures the concentration of NH3 in a cross-section of the emission plume downwind of the source. The emissions could he registered for three weeks after application of manure. The results of this method indicate that the long term emissions only contribute 1-2 % to the total emission level. This is supported by calculations that used data obtained from atmospheric gradient measurements. Both the effect Of SO2 on the ammonia deposition levels and the long-term emission fluxes are not enough to explain the observed ammonia gap. lt seems that several counteracting effects, some of them emerging from the new emission reduction regulations, contribute to the ammonia gap. An integrated approach to abate ammonia emissions is therefore needed. The implementation and regulation of production ceilings for reactive nitrogen might be a good option. 20 refs.


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