Lichen exposure

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The lichens exposure is a bioindikatives method for determining air pollution . With their help, the effects of air pollution are recorded integrally.

background

In contrast to chemical-physical measurement data, the results obtained through biomonitoring show the interactions of various individual components. Organisms that are ubiquitous in the study area are preferred as bioindicators. The lichens that meet these requirements are extremely sensitive to air pollution, as their absorption of substances and thus the absorption of pollutants takes place almost exclusively through the air and precipitation. In contrast to higher plants, they do not have a protective layer , so that air pollutants can penetrate the lichen largely unhindered. Lichen lacks the ability to regenerate quickly. Since they do not have the ability to actively excrete pollutants, an accumulation takes place in them . Lichen can also absorb pollutants in the winter months because they are metabolically active even at low temperatures .

Hypogymnia physodes on a log

The lichen species Hypogymnia physodes has proven itself for the method of lichen exposure . It is particularly sensitive to the simultaneous action of ozone and sulfur dioxide . However, it is almost completely absent in regions that are used intensively for agriculture.

The lichen and the bark are usually removed from felled trees, preferably oaks . For several months of acclimatization , the lichens are attached to a frame made of untreated wood with tree resin and stored in a low-emission location that is climatically similar to the later exposure location. The actual exposure takes place with the help of so-called lichen tables or lichen wheels. Wicker panels are resin-free wooden panels with holes in which the pieces of bark are embedded. Lichen wheels are driven by the wind via cup-shaped blades. Six lichen bodies are distributed evenly around the vertical axis at a certain height , comparable to the Mank carousel . In both geometries, the lichens are exposed for 360 days, with the start time around October 1st. At the beginning and end of the exposure period, the lichens are recorded photographically. The comparison between the photographs provides the measurement result, which is output as the degree of damage.

The exposure device should have a free flow and be constructed in such a way that the exhibits are on average one and a half meters above the ground. If braided panels are used, they should be oriented to the north in order to prevent the influence of solar radiation on the embedding medium. Is in areas where Hypogymnia physodes occurs naturally, the practice of 'lichen exposure, the procedure is in addition lichen mapping apply.

Lichen exposure was developed in the 1960s by Helfried Schönbeck from what was then the State Institute for Immission and Land Use Protection of the State of North Rhine-Westphalia. It was standardized in 1991 with the VDI 3799 Part 2 guideline . As early as the 1980s, lichen exposure was used for effect-related immission measurement.

literature

  • VDI 3799 sheet 2: 1991-10 measurement of immission effects; Determination and assessment of phytotoxic effects of immissions with lichens; Method of standardized lichen exposure (Measurement of immission effects; measurement and evaluation of phytotoxic effects of ambient air pollutants (immissions) with lichens; method of standardized lichen exposure). Beuth Verlag, Berlin. ( Summary and table of contents online )

Web links

Individual evidence

  1. ↑ VDI 3957 sheet 1: 2014-09 Biological measurement methods for determining and assessing the effects of air pollution on plants (biomonitoring); Basics and objectives (Biological measuring techniques for the determination and evaluation of effects of air pollutants on plants (biomonitoring); Fundamentals and aims). Beuth Verlag, Berlin, p. 3.
  2. ^ R. Guderian, K. Küppers, R. Six: Effects of ozone, sulfur dioxide and nitrogen dioxide on spruce and poplar with different supplies of magnesium and calcium and on the leaf lichen Hypogymnia physodes. In: Commission for keeping the air clean in the VDI and DIN (ed.): Current forest damage. VDI-Verlag Düsseldorf 1990, ISBN 3-18-090560-3 , pp. 657-701.
  3. ↑ Isabelle Franzen-Reuter: Effects of experimental nitrogen administration on the nitrogen content of selected epiphytes. In: Hazardous substances - cleanliness. Air . 73, No. 4, 2013, ISSN  0949-8036 , pp. 159-166.
  4. ^ A b Franz Joseph Dreyhaupt (Ed.): VDI-Lexikon Umwelttechnik. VDI-Verlag Düsseldorf 1994, ISBN 3-18-400891-6 , pp. 496-497.
  5. ↑ a b Helfried Schönbeck: A method for recording the biological effects of air pollution by transplanted lichens. In: Dust - cleanliness. Air . 29, No. 1, 1969, pp. 14-18.
  6. ↑ VDI 3799 sheet 2: 1991-10 measurement of immission effects; Determination and assessment of phytotoxic effects of immissions with lichens; Method of standardized lichen exposure (Measurement of immission effects; measurement and evaluation of phytotoxic effects of ambient air pollutants (immissions) with lichens; method of standardized lichen exposure). Beuth Verlag, Berlin, p. 4.
  7. ↑ Willfried Nobel, Heike Beismann, Jürgen Franzaring, Reinhard Kostka-Rick, Gerhard Wagner, Walter Erhardt: Standardized biological measurement methods for determining and evaluating the effects of air pollution on plants (bioindication) in Germany. In: Hazardous substances - cleanliness. Air. 65, No. 11/12, 2005, ISSN  0949-8036 , pp. 478-484.
  8. ↑ Harald Bartholomess: Effect-related long-term observation of environmental pollution. In: Hazardous substances - cleanliness. Air. 60, No. 9, 2000, ISSN  0949-8036 , pp. 361-366.