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Title:
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Scientific basis for an integrated nitrogen approach
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Author(s):
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Published by:
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Publication date:
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ECN
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1-10-1999
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ECN report number:
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Document type:
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ECN-RX--99-033
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Article (scientific)
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Number of pages:
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18
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Published in: Paper presented at the 10th Nitrogen workshop in Copenhagen, 23-26 August 1999. - Submitted to Plant and Soil (), , , Vol., p.-.
Abstract:
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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