Dust deposit

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As dustfall the "deposition of substances that is as a dry dust , together with rain water enter or as gaseous components from the air to surfaces such as soil, plants, buildings and water", respectively. In the past, dust deposits were seen as a visible sign of air pollution . The French meteorologist Gaston Tissandier collected dust as early as the 1870s on two square meter sheets of paper in order to determine the size, shape and number of the particles.

meaning

Due to its size or because it binds to raindrops, dust precipitation does not have a direct impact on health as it is only inhaled to a small extent. However, permanent dust precipitation leads to harmful changes to the soil and can be hazardous to health if the fruit or animal feed is placed on the market .

Together with the measurement of the suspended dust concentration , the recording of the dust precipitation serves to characterize the immission situation.

In the TA Luft , under number 4.3.1, a value of 0.35 g / (m 2 · d) is specified as the immission value for dust precipitation to protect against considerable nuisance or considerable disadvantages . The averaging period is one year. There is no distinction between dust precipitation of natural and anthropogenic origin.

Metrological recording

Dust precipitation is recorded with so-called passive collectors , which work according to two fundamentally different methods: collection in collecting vessels and on adhesive surfaces.

One of the best-known and most common methods for measuring dust precipitation is the Bergerhoff method , in which solid and liquid precipitation collects in a vessel during the sampling period, which is then dried. In the TA Luft from 1986, the measurement of dust precipitation with the Bergerhoff method was prescribed.

Similar to the Bergerhoff collector are the Hibernia and Löbner-Liesegang devices, which are no longer in use today. What both devices have in common is that the funnel and collection bottle are essential components.

When collecting on adhesive or acceptor surfaces, the dust deposit is collected on a transparent film made of acrylic ester polymer. The collecting surface is located in a wind-calmed cylinder , which largely excludes particle separation by separation mechanisms that differ from sedimentation . The collected particles are then evaluated using a light microscope . In earlier years, opaque films were used as adhesive films, which were coated with Vaseline and evaluated gravimetrically. A disadvantage of this process was that at higher temperatures the adhesive could become liquid and flow off the film.

The difference between the measured values ​​obtained with the various methods can be up to 50%.

Individual evidence

  1. ↑ a b LANUV: Dust precipitation. State Office for Nature, Environment and Consumer Protection North Rhine-Westphalia , accessed on July 20, 2016 .
  2. ↑ a b c d Günter Baumbach: Air pollution control . Springer-Verlag Berlin, Heidelberg, New York, 2nd edition 1992, ISBN 3-540-55078-X , pp. 215-216.
  3. ^ Carsten Möhlmann: Dust measurement technology - then until now. In: Hazardous substances - cleanliness. Air . 65, No. 5, 2005, ISSN  0949-8036 , pp. 191-194.
  4. ↑ VDI 3790 sheet 1: 2015-07 environmental meteorology ; Emissions of gases, odors and dusts from diffuse sources; Basics (Environmental meteorology; Emissions of gases, odors and dusts from diffuse sources; Fundamentals). Beuth Verlag, Berlin, p. 16.
  5. ^ A b c Franz Joseph Dreyhaupt (Ed.): VDI-Lexikon Umwelttechnik. VDI-Verlag Düsseldorf 1994, ISBN 3-18-400891-6 , p. 1120.
  6. ↑ VDI 4320 sheet 2: 2012-01 Measurement of atmospheric deposition; Determination of the dust deposition according to the Bergerhoff method (Measurement of atmospheric depositions; Determination of the dust deposition according to the Bergerhoff method). Beuth Verlag, Berlin. P. 4.
  7. ↑ VDI 2119 sheet 3: 1972-06 measurement of particulate precipitation; Determination of the particulate precipitation with the Hibernia and Löbner-Liesegang device. Beuth Verlag, Berlin. P. 1.
  8. ↑ VDI 2119: 2013-06 Measurement of Immissions; Sampling of atmospheric particles> 2.5 µm on an acceptor surface with the passive collector Sigma-2; Light microscopic characterization and calculation of the number sedimentation rate and the mass concentration (ambient air measurements; Sampling of atmospheric particles> 2.5 µm on an acceptor surface using the Sigma-2 passive sampler; Characterization by optical microscopy and calculation of number settling rate and mass concentration). Beuth Verlag, Berlin. P. 3.
  9. ↑ Ernst Effenberger: Investigations into the measuring accuracy of the dust precipitation measurement through adhesive foils. In: dust . 19, No. 9, 1959, ISSN  0949-8036 , pp. 313-319.
  10. ↑ Wolfgang-Dietrich Kampf, Bernhard Schmidt: Determination of the dust precipitation through transparent adhesive surfaces. In: Dust - cleanliness. Air. 27, No. 9, 1967, ISSN  0949-8036 , pp. 395-399.