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Title:
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Development of instrumentation for the measurement of atmosphericconcentrations of acidifying compounds
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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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1996
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ECN report number:
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Document type:
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ECN-C--96-039
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ECN publication
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Number of pages:
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Full text:
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53
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Download PDF
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Abstract:
Several novel techniques have been developed for sampling and detectionof atmospheric trace constituents. A diffusion denuder is described for the
continuous measurement of atmospheric ammonia. This compact instrument is
fully automated and suited for routine deployment in field studies. The
precision is sufficiently high for micrometeorological studies of air-surface
exchange of ammonia. A new principle of sampling aerosol particles by means
of steam injection with the consequent collection of grown droplets has been
established. On the basis of the new sampling principle a prototype of an
aerosol sampler was designed which is capable of sampling particles
quantitatively down to several nanometers in diameter. During measurements
the sampler proved to be stable, working without any assistance for extended
periods of time. Comparison of the sampler with filter packs during
measurements of ambient-air aerosols showed that the sampler gives good
results. An automated system has been developed for the collection, in-line
preconcentration and analysis of acidifying atmospheric gases. Collection of
HCl, HNO2, HNO3 and SO2 from ambient air is carried out with a wet annular
denuder. The manifold described with two sample loops and two concentrator
columns operating in parallel allows automated collection and analysis of two
air samples per hour. A computer programme has been developed for automated
performance. It allows the system to run unattendedly during extended periods
as all the functions, including data processing, are computer-controlled.
Factors affecting the performance are reported. Ambient measurements for
Petten, The Netherlands, are presented which show the capability of the
system for continuous monitoring of atmospheric acidifying gases. A
simplified Seld instrument for the continuous measurement of HCl, HNO2,
HNO3 and SO2 was constructed, which is based on the same principles as the
apparatus described above. The applicability of the system is demonstrated in
a measurement campaign at Petten, The Netherlands. 23 figs., 3 tabs., 39 refs.
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