Bioindicators 1991

Map Description

Map 03.07.1 Lichen Mapping

The map gives the findings of lichen mapping according to the evaluative scale of VDI-Guideline 3799 Part 1 (cf. Tab. 1).

The category “extremely high” for Air Quality Classes 1 and 2 is characterized by the extensive lack of naturally-occuring lichen. Only the toxic-tolerant crustose lichen Lecanora conizaeoides appears frequently in these areas.

The category “very high” for Air Quality Classes 3, 4, and 5 describes areas where Lecanora conizaeoides is joined by a few, usually damaged, foliose lichen, present in small numbers.

A somewhat greater number of species and coverage first appear in the zone “high”, for Air Quality Classes 6, 7, 8, and 9.

Areas defined in the VDI-Guideline 3799 as “moderate”, “low”, and “very low” were not found within the study area that includes the entire area north of Berlin up to the border between the states of Brandenburg and Mecklenburg-Vorpommern. The three most severely polluted zones were differentiated into 9 air quality classes and are color-coded. They also clearly show a particular load in the inner city area (Air Quality Class 1). Even the toxic-tolerant lichen Lecanora conizaeoides was clearly impaired in frequency and vitality in this area.

Beyond a survey of lichen on the chosen trees, a comprehensive random sample study was conducted on the lichen flora of the area. The collected data underscore the above findings in an impressive manner. Only about 20 % of the species found could be characterized as frequent. There is an apparent imbalance between a few, widely spread, toxic-tolerant species, and a large number of more sensitive species, found only occasionally.

The load zones documented in Map 03.07.1 also find expression in the distribution of individual species. Species of potentially high incidence, like the shrubby lichen Evernia prunastri, can exist only in the less damaged areas north of Berlin (cf. Fig. 2). Moderately sensitive species, such the foliose lichen Parmelia sulcata, very common in Germany, are also well distributed in the study area. But their population is only sporadically found in urban areas, border areas, and in the more strongly loaded by pollution south of Berlin.

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Fig. 2: Distribution of Lichen (Evernia prunastri (a), Parmelia sulcata (b) in the Berlin/Brandenburg Area in 1991
Image: Linders 1991

A summarized determination is that the greatest part of the study area is influenced by considerable pollution. The existence of natural lichen vegetation is not possible, particularly south of the line Neuruppin-Angermünde. This means the entire city of Berlin and its near surroundings have an air pollution load characterized as “very high” to “extremely high”, according to VDI 3799 Part 1. A particularly loaded zone is the Berlin inner city boroughs (cf. Rabe and Beckelmann 1987).

The northern part of the study area is in no way to be characterized as a pure air area, in spite of the relative diversity of species. The lichen here are spare relics of previously rich vegetation. They are influenced by air pollutions transported over long distances that lead to macroscopically visible damage on sensitive species, and allow reproduction only at especially favorable growth locations.

The extensive gap of air quality over large areas between the less loaded north and the strongly loaded south, as well as the middle of the study area must be emphasized. The air quality gradient findings seem only somewhat due to the influence of the Berlin metropolitan area, for there are only small differences between the city center and the surrounding areas of the city. It must be asssumed that lichen in Berlin’s environs are also considerably impaired by pollution transported over long distances.

In comparison with a methodically similar mapping of the state of Hessen (Kirschbaum and Windisch 1995), it is striking that no areas of “extreme load” were determined in Hessen. In the Berlin area, however, more than two-thirds of all study sites are in areas classified as “very high” and “high” (categories used only in Berlin). Lichen studies allow comparisons of air quality between large parts of the Berlin environs and the Rhein-Main area and north Hessen.

It should be emphasized that evaluations of naturally-occuring lichen vegetation primarily enable statements to be made about the most recent pollution burdens. Lichen are recolonizing in the Berlin area very slowly in spite of the improvement in air quality. This means existing data documents a situation that no longer corresponds to the current pollution burden. It is to be assumed that the present reduction of pollution will be reflected by a medium-term recovery of lichen occurrence, insofar as new pollution sources do not gain in significance. Regular updating of maps is required to monitor such recolonization processes and the improvement of air quality related to it.

Map 03.07.2: Exposure of Hypogymnia physodes

The foliose lichen Hypogymnia physodes showed thallus mortality rates of 0 -19 % in the study period 1991/92. A comparable study in West Berlin at the beginning of the 80’s determined thallus mortality rates of 42 -87 % (cf. Cornelius et al. 1984). A clear improvement of air quality over the last decade can be assumed (cf. Fig. 3).

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Fig. 3: Thallus Mortality Rate of Hypogymnia physodes in the Berlin Urban Area since 1981/82
Image: after Cornelius et al. 1984, Mezger 1992, Mezger 1995

The Hypogymnia physodes sorale mortality rate of 3 – 94 %, however, makes it clear that a relevant pollution burden continues to exist in the city. The lowest average loss of vitality was 27 % and was determined in Berlin’s environs in 1991/92, while the mean sorale mortality rate in Berlin itself was 66 %.

This spatial pattern corresponds to a great extent to detected sulfur levels in exposed lichen. The highest sulfur values in 1991/92 were 2.3 g/kg dry matter (dm) occured in inner city boroughs with widespread coal-burning domestic heating. There was, however, only a small difference between the 1.9 g/kg dm level determined by sampling points in Berlin and the 1.8 g/kg dm level in the surrounding areas. A control location about 70 km north of Berlin showed a lesser background load of 1.4 g/kg dm.

The Hypogymnia physodes sorale are much more sensitive to SO2 than the thallus and show clear effects of pollution. An increase of sulfur levels in Hypogymnia physodes in Berlin documents the negative influence of sulfur compounds on lichen vitality. There are highly significant correlations between the concentrations of SO2, airborne particulates, and the vitality of sorale and/or the sulfur level of lichen thallus (Metzger 1992).

In Berlin, high sulfur accumulation in the lichen thallus corresponds to high degrees of damage to the sorale. In the surrounding areas, however, equally high sulfur levels appear with lesser degrees of damage. The small spatial differences in sulfur levels in Hypogymnia physodes allow two sources of sulfur to be presumed. The increased sulfur levels in lichen thallus in Berlin would be due to higher SO2 levels, whereby the higher sulfur levels in lichen in the surrounding areas would be caused by ammonium-sulfate inputs from agricultural activities. Only gaseous SO2 has a direct toxic effect on Hypogymnia physodes. High sulfur levels in surrounding areas during the growing season are due to agricultural fertilizers and lichen vitality is relatively high.

According to VDI 3799 Part 2, damage to higher plant leaves and/or needles is to be expected when lichen thallus mortality rates are between 10 – 35 % (cf. Tab. 2). This threshold was exceeded at four sampling points in Berlin in 1991/92. A danger to crop and decorative plants from winter pollution is thus possible at the inner city sampling points of Mariendorf, Karlshorst, Friedrichshain and Hellersdorf. The extensive damages to sorale at sampling points in the highest damage categories allow the presumption of great reproduction impairment to Hypogymnia physodes in Berlin, so that this species cannot spread out in the city, although it is widely distributed throughout the surrounding areas.

Map 03.07.3: Accumulation of Inorganic Pollutants in Pine Needles and Rye Grass

The map depicts levels of lead and fluorine in pine needles in 1991, and in rye grass exposed at sampling points. Sulfur levels are given only for accumulation in pine needles in 1991. The values document accumulation caused by pollution in the entire study area. The inner city sampling points usually show high levels. Accumulation in rye grass did not reach any thresholds that were eco-toxologically problematic in 1993 (cf. Tab. 4).

Lead levels in pine needles show a clear differentiation with ranges of values from 2.0 mg/kg dry matter (dm) in Neuseddin to 15.2 mg/kg dm in Blankenburg. Only three sampling points in surrounding areas were classified as unloaded. The study area as a whole shows a medium load level. The increase of area mean values underlines the increase of concentrations from surrounding areas of 6.2 mg/kg dm, over outer boroughs of Berlin with 6.9. mg/kg dm, to inner city sampling point values of 8.3 mg/kg dm. Burdens of this heavy metal continue to be significant in spite of the introduction of unleaded gasoline.

Fluorine levels in pine needles were between 0.7 mg/kg dm at Tegel airport and 30.6 mg/kg dm in Blankenburg. Low levels of < 10 mg/kg dm were determined at 64 % of sampling points. High levels of > 20 mg/kg dm were determined at 8 % of sampling points. The other values were in the middle range. Area segment mean values of inner city boroughs were 11.6 mg/kg dm and are above the total area mean value of 9.6 mg/kg dm. Burdens of outer Berlin boroughs are roughly average, and burdens of surrounding areas are less than average. The surrounding areas, however, have the largest range of variation among area segments. It may be concluded that this is due to local pollution sources. In the regional distribution there is, in total, a clear difference between the eastern and western halves of the study area. The eastern part is more strongly burdened, both in the surrounding areas and in the city. This is possibly due to the greater use of brown coal for domestic heating. Values at 36 % of sampling points were above the fluorine toxic effects for plants threshold of 10 mg/kg dm (Kreutzer 1978).

Sulfur levels in pine needles in the study area were between 1,270 mg/kg dm at Siethen and 2,190 mg/kg dm in the Zehlendorf borough. The area segment mean for the inner city was 1,905 mg/kg dm. That is clearly higher than the outer boroughs with 1,744 mg/kg dm, and the surrounding areas with 1,621 mg/kg dm. The total area mean value was 1,725 mg/kg dm. This is in the high range. Regional peak values are mainly in the inner city and in East Berlin. In spite of contradictory literature regarding evaluation of sulfur values, it can be determined that an influence of pollutions can be recognized at 83 % of sampling points. At 11 % even long-term damages in the form of growth reduction cannot be ruled out.

Lead levels in rye grass show a great spatial variability in pollution accumulation. The total area mean value was 1.5 mg/kg dm in 1993. For inner city boroughs it is is 1.6 mg/kg dm and is somewhat greater than the surrounding areas with 1.3 mg/kg dm. Boroughs in East Berlin are particularly burdened by higher lead pollution, but the guideline index value of 8 mg/kg dm (cf. Tab. 4) was not reached at any sampling point. No direct danger exists at this time.

Flourine levels in rye grass in the study area in 1993 were between 3.0 mg/kg dm at the sampling point Brieseland and 11.2 mg/kg dm at Tempelhof Airport. The total area mean value was 5.2 mg/kg dm; the mean value at sampling points in surrounding areas was 4.6 mg/kg dm. The inner city value of 5.5 mg/kg dm is clearly high. The limit value of 30 mg/kg dm was not reached.

A comparison of current pollutant accumulation in rye grass with studies by Cornelius et al. 1984 clearly show that the pollution load of Berlin has considerably decreased for certain substances (cf. Fig. 4). Maximum values in 1993, compared to 1981 values, were lead, 43 %; fluorine, 28 %; and sulfur, 67 %. Minimum values in 1993, compared to 1981 values, were lead, 73 %; fluorine, 44 %; and sulfur, 72 %. In 1981, threshold values for pollutant load were reached and/or exceeded. In 1993, the values were substantially lower.

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Fig. 4: Pollutant Contents in Rye Grass at Selected Sampling Points in the Berlin Urban Area in 1981 and 1993
Image: after Cornelius et al. 1984, Kuznik 1993

In spite of the generally reduced pollutant load, lead and sulfur retain potential significance for toxic effects to the ecology and/or plants. Fluorine could cause load on plants at certain locations.

Map 03.07.4: Accumulation of Organic Pollutants in Green Kale

The map shows the relative burdens of organic pollutants along an east-west transsect in the study area in autumn, 1993. The levels of studied materials underscore high load in the inner city areas. Some sampling points in surrounding areas also showed peak levels. The high motor vehicle dimension figure in inner city boroughs show auto traffic to be a considerable cause of total PAH load.

The average PAH accumulation in terms of fresh weight in the autumn of 1993 was 12 times higher than in the summer of 1994. The ratio between individual sampling points in 1994 was similar to that in 1993, but at a considerably lower level and without local maximum values. It was determined that the danger is particularly high in the winter half-year with the greater use of heating facilities. The effects of high levels in autumn are also to be observed in the outer city areas and/or surrounding areas.

Summer levels of PAH on the whole are categorized as less disturbing. Benzo(a)pyrene (BaP), however, is to be evaluated more critically. The burden for the total area is high, with an average level of 12.8 mg/kg dm in the autumn of 1993. Even locations at some distance from the Berlin city limits, such as Falkensee, Seeburg, Altlandsberg, Neuenhagen, and Rüdersdorf, show values found in south German industrial metropolitan areas. Some locations were more than twice as high as at comparable locations in the Munich inner city (LfU Bayern 1995). High benzo(a)pyrene levels in autumn months are explained by domestic heating.

The motor vehicle dimension figures allow a differentiation of stronger and weaker influences. The figure at the edge of the city and surroundings areas in the state of Brandenburg does not exceed 0.6. Inner city values are between 0.7 and 1.0. The highest dimension figure of 0.99 was determined at the Charlottenburg borough station in summer, 1994, in the direct vicinity of the city freeway. More than 150,000 motor vehicles a day drive by (cf. Map 07.01, SenStadtUmTech 1996b).

PCB levels on the whole verify a medium load level in the study area. The depicted station values show a decreasing tendency from the inner city to the city limits and, particularly in eastern areas, this decrease continues into rural areas. The mean value of stations in the city was 13.9 mg/kg dm, almost twice as high as the mean for surrounding area at 7.8 mg/kg dm. Some strong pollutant load differences do appear. Levels at the Charlottenburg borough site were 90 mg/kg dm, almost 40 times the minimum level of 2.3 mg/kg dm at the Falkensee site, and three times the 30.8 mg/kg dm level at the directly neighboring Tiergarten site, also a highly loaded location. The Ruhleben waste combustion facility is a possible cause. The Charlottenburg, Tiergarten, and Mitte stations show high accumulation values. This can be traced back to the main traffic routes directly beside them.

Determined PCDD/PCDF values show pollution accumulation throughout the year at a generally medium load level. The emphasis is on the winter months, when values 3 times higher appear. Summer levels can be viewed less critically, but also show accumulation caused by pollutions. Local pollutant centers with I-TEQ values (International Toxicity Equivalents) below 3.0 were found in the autumn of 1993 in Haselhorst, Wedding, Hohenschönhausen, Seeburg, Lichtenberg, Hellersdorf, and Rüdersdorf. The analysis of individual dioxins, which indicate specific emitters, showed a high influence of domestic burning at the monitoring stations Tempelhof and Marienfelde, as well as Elstal and Kartzow at the western edge of the transsect. There were dioxin inputs due to traffic at the sampling points Wedding, Weißensee, Hohenschönhausen, Neuenhagen, and Werder.

Motorway Transsect

Ranges and levels of traffic pollutions were studied along a transsect of the A115 freeway southeast of the city of Postdam (cf. Fig. 5). PAH accumulation in green kale in the 500-meter-long transsect is high, according to the pollutant level classification definition. The mean value of sum PAHs of all twelve stations is more than 25 % above the upper reference value for medium load, 400 mg/kg fresh matter (fm). The unexpectedly lesser decrease of levels with increasing distance from the street can be explained, beyond a transport of motor vehicle exhaust gasses, by the overlapping of local pollutant sources and by long-range transport of pollutants.

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Fig. 5: PAH Totals, Benzo(a)pyrene, and Motor Vehicle Dimension Figure in the Vicinity of a Motorway Transsect near the City of Potsdam in Autumn, 1993
Image: after TÜV-Umwelt Berlin-Brandenburg GmbH 1995

Mean values of benzo(a)pyrene at two to five meters distance were 30 mg/kg dm, three times the upper reference value of the medium pollutant load category. The amount of the carcinogenic component benzo(a)pyrene in total PAH at all twelve sampling points averaged 4.3 % This is above the mean value of all stations in the east-west transsect during the autumn exposure period in 1993. Accumulated benzo(a)pyrene in plants was strikingly high along the entire 500 meter motorway. Besides the effects of motor vehicle exhaust gasses, it may be concluded that these high values derive from incomplete combustion processes of individual burning sites in surrounding settlements.

The amount of traffic pollutions can be made clear with the aid of a motor vehicle dimension figure. The graphic depiction of this dimension figure makes the pollution near to the freeway particularly clear (cf. Fig. 5).

The findings of green kale exposure are significant for human health because this bioindicator is a food crop. The “worst-case assumption” here would be a diet of foodstuffs solely from this area. This would expose humans in Berlin to a medium-to-high burden of organic pollutants. The ubiquitous soil burden of airborne pollutants is clearly exceeded. Average human inputs are probably within the range of toxic tolerance.

Traffic pollutions are a particular load factor in Berlin. The effect gradient of airborne organic pollutants along heavily travelled streets is particularly high near these streets. This means an increased risk of danger to human health in the direct vicinity of heavily-travelled streets and freeways.

The data of the Cadastre of Ecological Pollution Effects from 1991 -94 can be summarized by means of a simple method to a total evaluation of the surveyed sampling points. Material contents and/or evaluation schemes corresponding to measured minimums and maximums are ‘normed’ and summarized into a single value. Considerations of comparability allow only selected parameters to be included in this calculation. These parameters include lichen and rye grass exposure, pine analysis, as well as (not described here) pine needle evaluations and the exposure of tobacco and pinto beans (cf. SenStadtUmTech 1996a). The graphic depiction of data shows several basic patterns which are confirmed by individual findings (cf. Fig. 6).

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Fig. 6: Total Evaluation of Bioindicator Findings
Image: Umweltatlas Berlin

Mean values of the area segments “inner city”, “outer boroughs”, and “surrounding areas” do differ, as expected, but it is striking that this difference is not very great. One reason is the generally moderate load level of the inner city. Another reason is the sometimes clear environmental burden of outer boroughs and the surrounding areas. Some sampling points show pollutant values very similar to the inner city. There are apparently large-area background loads affecting surrounding areas, which is reinforced by local emissions in some cases.