01.03.1 Lead in Soils /01.03.2 Cadmium in Soils

Overview

Heavy Metals in the EnvironmentHeavy metals are natural components of soil. Most elements are only present in minimal, insignificant eco-toxicological concentrations in undisturbed locations in the greater Berlin area. A few heavy metals are important as trace elements for physiological processes in plants and animals.

Heavy metals are introduced into the eco-system by the manufacture and use of materials containing heavy metals as well as the disposal of this waste. Soil is contaminated by material from the air and by direct depositing of pollutants. The accumulation of contaminants is aided by the capability of soil to bind them with clay minerals or organic substances, for example.

Lead and cadmium are widely distributed in the environment and are considered particularly toxic elements. Their accumulation has multiple effects on the usability and functions of soil in the eco-system.

Effects of CadmiumCadmium is an especially toxic heavy metal that is very mobile in soil. Even minimal amounts in soil that has a low pH or humus level will result in cadmium uptake into plants. Levels exceeding guidelines for foodstuffs or feeds can result.

Effects of LeadLead is less mobile and is absorbed by plant roots only in exceptional cases. Contaminated soil can result in pollution by both elements onto the surfaces of plants. Even minimal contents in soil can negatively effect plant growth and damage soil organisms.

Very high lead or cadmium levels in playgrounds, allotment gardens and other areas can cause health risks for small children by oral ingestion. If heavy metal contamination exceeds the binding capability of the soil, there is a danger that heavy metal compounds can flow with percolation (seepage) into the groundwater.

Heavy metal soil contamination is particularly problematic because they are not degraded in soil. Heavy metals in soil cannot be permanently eliminated. At best they can be locally reduced by a redistribution in the eco-system or removed from circulation by immobilization.

Statistical BaseMaps 01.03.1 and 01.03.2 were prepared by evaluating about 2,900 measuring points of the measuring programs. The measuring programs were initiated to collect comprehensive data regarding heavy metal contamination of specific area uses and to characterize the contamination of larger portions of the city and its bordering areas.

Analyses were not taken into consideration which were made at individual locations for old contaminated sites in the course of initial evaluations and preparations for restoration commissioned by the Berlin Department of Urban Development and Environmental Protection or by borough environmental agencies. Comprehensive heavy metal measurements were regularly conducted in this context, so the maps presented here depict only part of the known soil pollution.

The map shows measurement data next to each other which were collected at different times at areas of varying uses in Berlin and its bordering lands (see Table 1). A classification of the underlying studies, test times and methodology is not possible on the map. The measurements are excerpts from the Heavy Metal Data Base maintained by Department IIIA5 of the Berlin Department of Urban Development and Environmental Protection. Complete information regarding depicted measurement points can be accessed from this Data Base.

Tab. 1: Description of the Measurement Survey

Methodology

Condition and Use of Tested SitesThe depicted measuring points show the location of each tested site. In the case of sewage farms in the south of Berlin or agricultural areas, the middle point of these areas is marked. The use of each site at the time of testing is given. Differentiated were allotment gardens, house yards, agricultural fields, horticulture, current and former sewage farms, forests, green and open spaces, playgrounds, and miscellaneous uses. Measurements for green and open spaces were taken both in larger parks and in incidental green spaces in other use areas, such as schools.

Test DepthThe given measurement values document lead and cadmium only in the upper centimeters of soil.

Some measurement values of deeper soil layers were determined at some locations, but are not considered here. The majority of values represent mixed tests of the upper 20 cm of soil; a portion of the sewage farms in northeast Berlin were tested in the upper 30 cm.

The test depth in forests was between 5 and 35 cm. The heavy metal level listed here is for the upper mineral soil horizon (layer). Heavy metal levels in organic horizon are not portrayed. Heavy metal levels in playgrounds are documented for the uppermost soil horizon or the material used as a surface. All values refer to materials found in the upper 10 cm of soil. Playground sand levels are not given. Allotment gardens, house yards, horticultural and agricultural areas usually have several values dating from different times, or because of differing methods of analysis. The highest levels for lead and cadmium are given here because these values can be cause for considering amelioration (improvement) or restoration programs.

Methods of AnalysisA direct comparison of measurement values should note that different extraction methods were employed for an analysis of soil samples (see Tab. 1). Measurement values obtained by 1.5 NHNO3-, 2 M HCl- or aqua regia (Königswasser) analysis register about 80-90% of total heavy metals. Total levels are given (HF/HClO4-analysis) for a portion of tests in Berlin forests, the majority of values in green spaces, and measurement points in Schönweide.

Index ValuesIncreasing knowledge about the extent and effects of heavy metal soil contamination shows that measurement results can only be evaluated for specific protections and uses. Correspondingly differentiated index value catalogs are currently in discussion (LAGA 1990, Eickmann & Kloke 1991, LÖLF 1988).

Proceeding from these discussions, the Berlin Department of Urban Development and Environmental Protection is working on index values for the evaluation of soil contamination levels in allotment gardens and house yards (SenStadtUm 1991a) and for estimated contamination levels in agricultural and horticultural soil (SenStadtUm 1991b). The Berlin Department of Health publishes evaluation criteria for soil contamination in playgrounds (SenGes 1991). These index value catalogs evaluate possible dangers in the use of contaminated surfaces and are oriented to the necessity of translating evaluation results into concrete administrative action.

Value gradations (contamination levels) depicted in the maps correspond to index values in Table 2, so that concrete recommendations for uses of specific locations can be derived, based on their contaminant levels. Values given for other uses can be interpreted only in comparison to the natural heavy metal levels of soil in Berlin.

Tab. 2: Index Values for Assessing Lead and Cadmium Contamination of the Soil

Map DescriptionLead and cadmium soil contamination in Berlin varies considerably, particularly in allotment garden, agricultural, sewage farms, and forests. The number and distribution of measuring points for these areas give representative values. Other areas were tested with a much lesser test density. These surveys give only an initial overview of contamination degrees and distribution.

Tab. 3: Lead and Cadmium Levels in Soil in Various Use Categories

Allotment Gardens and YardsThe topsoil of allotment gardens everywhere is considerably contaminated with lead and cadmium. Both the 50th percentile value as well as the average value exceed greatly natural soil values - and that in areas where heavy metals can be absorbed by food crops. This was demonstrated by the Berlin Heavy Metal Measurement Survey analysis of food crops (see 01.03.3). In some cases, both elements were present at such levels that health risks incurred by direct contact with soil could not be ruled out.

Contaminated allotment gardens are found in all parts of the city, most heavily in the inner city. Lead levels show a more clear gradient than cadmium levels. There are considerable contamination level differences within a single area of gardens, sometimes even within a single garden.

The measurement values of differentiated follow-up tests of 1,600 allotment gardens conducted in 1989 and 1990 are not depicted in the map for graphic reasons. The values found at these sites are given in Table 3.

House yards are less contaminated. Levels exceeding index values were determined at few locations.

Agriculture and HorticultureThe majority of tested agricultural areas are considered only slightly contaminated. More than 50% of tested areas show levels within natural ranges for lead and cadmium. There is a clear regional differentiation of contamination. Cadmium levels exceeding applicable index values were found almost only in sites around the Gatow sewage farms. Lead levels are high here too, although few locations exceeded the index values. Soil contamination correlated with contamination of food and feed crops, also unusually high here (compare 01.03.3).

High heavy metal levels were also found in green spaces in northwest Berlin and in Lübars, due to larger amounts of humus and its greater capability for binding heavy metals.

Horticultural businesses did not exceed soil index values. Determined lead and cadmium levels were in the range of natural levels.

Sewage farmsParticularly high cadmium contamination was found in almost all soils of former or still functioning sewage farms in Berlin and its vicinity (compare 01.10). The sewage farms in southern Berlin are more heavily contaminated than those in Gatow or northeast Berlin. There are great pollution gradations within single

sewage farms. Soil contamination in the great majority of former sewage field areas, mainly used today for agricultural purposes, lead to the expectation of disturbing cadmium levels in the crops cultivated here. Contamination in crops cultivated on sewage farms have been determined. (cf. 03.03.3, Grün et al. 1990).

Lead is also accumulated in higher concentrations in sewage field soils, but concentrations remain under applicable index values. The homogeneous pollution levels determined in the test areas indicate that untested areas will have comparable heavy metal concentrations.

Forests and Green SpacesHigh lead and cadmium levels were found in almost all forest topsoils. These values were, as a rule, under those found in areas for heavier anthropogenic (human) use (cf. Table 3). Heavy metal concentrations in organic horizon (not depicted) are usually higher than in mineral topsoil.

Contamination in depicted green spaces and other uses cannot be interpreted in context because of their wide heterogeneity. The inner city again shows higher contamination. Contamination levels in Schöneweide document the range of variation possible in inner-city areas.

Some playgrounds are contaminated with heavy metals. Some contamination levels were so high that health risks caused by direct contact with the soil cannot be ruled out.

Causes of Pollution

DepositionsCauses of lead and cadmium soil contamination are mostly additives of contaminated materials (building rubble, cinders) some of which come from refuse dumps or industrial sites.

Such land fill is especially practiced in allotment gardens and house yards, green spaces and miscellaneous use areas. 115 allotment garden areas in West Berlin are on old deposit sites, old industrial sites, or suspected old contaminated sites. Conspicuous are large areas on the edge of West Berlin used today for allotment gardens (SenStadtUm 1991c). In the inner city there are large deposits of debris.

The highest heavy metal values are regularly found at these locations and are usually due to anthropogenic deposits. Significant contamination also appears in small areas, often from building activity or land-fill in gardens.

Soil ConditionersConsiderable heavy metal deposits are also found in allotment gardens, house yards and green areas because of the use of contaminated compost and soil conditioners, especially from regular and long-term use. Contaminated composts at many locations were confirmed by the Berlin Heavy Metal Program. This is primarily caused by the composting of polluted waste (i.e., ash). The previously widely practiced use of contaminated sewage sludge compost (fertilizer) in allotment gardens, house yards and green spaces (used today only in small areas) contributed to soil contamination. Sewage farm sludge was used as soil conditioner for agricultural areas around the Gatow sewage farms.

Waste WaterSoil contamination in current and former sewage farms is due to contaminants in their waste waters. The contaminant spectrum of waste water is reflected in the soil. Variations in pollutant level between different sewage farms and within individual sewage farms are due to the length and intensity of waste water flow and origin. It is assumed that pollutants in waste water and treatment intensity were previously significantly higher than at sewage farms in use today.

Variations of pollution within individual sewage farms are due to non-homogeneous use. Soil contamination decreases with the distance from the waste water discharge pipes. Especially high values are regularly found in sludge drying areas and sedimentation basins. These relationships are clearly seen in comparing contamination levels in the 01.10 Map of Use of Sewage farms.

The lead and cadmium contamination around the Tiefwerder meadows exemplifies the effects of periodic flooding by contaminated surface waters.

Contamination of playgrounds is due to the use of contaminated surfacing and building materials, such as cinders and building rubble.

Inputs from the AirAirborne heavy metals also contaminate the soil. This influence is more clear for lead than cadmium because of the much greater amounts of lead. Soil in the inner city is more contaminated than soil at the edge of the city. The highest contamination is found in the vicinity of commercial emitters, but also directly next to heavily-traveled streets (see 01.03.3).

Forest contamination is almost entirely due to airborne pollutants. Pollutant sources cannot be clearly determined in gardens and agricultural areas, because of regular supplements of soil conditioners and other substances to the topsoil.

Tab. 4: Input and Accumulation of Lead and Cadmium in the Soil

Overall ViewThe diversity of pollution and causes of contamination make it clear that the depicted lead and cadmium levels in topsoils at many locations illustrate only part of the entire contamination present. Many sites show contamination of other heavy metals, such as zinc, copper and chrome. The risk potential of soil is clearly higher at these sites. Sewage farms and old contaminated sites often had organic pollutants in relevant concentrations. It can be assumed that pollutants have been carried or washed into deeper soil levels at landfill sites, sewage farms, and sites where topsoils have low binding capacities.

It can also be assumed that comparable contaminant levels are present at the many sites not yet tested, particularly in East Berlin.

The Berlin Department of Urban Development and Environmental Protection is preparing possible action plans for reducing risks arising from soil contamination (see Table 2). But these can only be sensibly conceived after a thorough investigation of the causes of specific site contamination, and in consideration

of the total spectrum of pollution. Additional information about soil characteristics is needed in some cases. This information would be given to users of those areas. Concrete safety or restoration measures have been initiated for particularly highly-contaminated playgrounds.

Literature[1] Biologische Bundesanstalt für Land- und Forstwirtschaften 1982:

Schwermetalluntersuchungen zum Forschungsprojekt über die Ansiedlung landwirtschaftlicher Betriebe im Bereich Karolinenhöhe und Gatow, not published.

[2] Blumenstein, O., Grunewald, K., Schubert, R. 1991: Das Altlastengebiet Rieselfelder Berlin-Süd - eine geoökologische Herausforderung, in: Potsdamer Geographische Forschungen, Bd.1.

[3] Bundesanstalt für Geowissenschaften und Rohstoffe 1991: Umweltgeochemische Bestandsaufnahme des Stadtgebietes Berlin-Schöneweide, not published.

[4] Ehrig, C., Stahr, K. 1988: Untersuchung von Laubkompost, TU-Berlin, Institut für Ökologie - Fachgebiet Regionale Bodenkunde, Gutachten im Auftrag der Senatsverwaltung für Stadtentwicklung und Umweltschutz Berlin, Berlin.

[5] Eickmann, T., Kloke, A. 1991: Nutzungs- und schutzgutbezogene Orientierungsdaten für (Schad-) Stoffe in Böden, Schriftenreihe des Verbands Deutscher Landwirtschaftlicher Untersuchungs- und Forschungsanstalten, Bd.1.

[6] Grün, M., Machelett, B., Metz, R., Kronemann, H., Podlesak, W., Schneider, J. 1990: Schwermetallbelastung von Boden und Pflanze im Gebiet der Rieselfelder Berlins, in: Exkursionsführer zum 102. VDLUFA-Kongress, Berlin, S.31-42.

[7] LAGA (Länderarbeitsgemeinschaft Abfall) 1990: Informationsschrift Altablagerungen und Altlasten. Abfallwirtschaft in Forschung und Praxis, 37, 1991.

[8] Landesforstamt Berlin 1989: Forstliche Standortserkundung, not published.

[9] LÖLF (Landesanstalt für Ökologie, Landschaftsentwicklung und Forstplanung Nordrhein-Westfalen) (Hrsg.) 1988:Mindestuntersuchungsprogramm Kulturböden, Recklinghausen.

[10] Metz, R., Herold, P. 1991: Humboldt-Universität zu Berlin /Institut für Pflanzenernährung und Ökotoxikologie Jena, Schwermetalluntersuchungen im Bereich der Rieselfelder im Norden und Süden Berlins, 1984-1987, not published.

[11] Niedersächsisches Landesamt für Bodenforschung (Hrsg.) 1988: F&E-Vorhaben "Kennzeichnung der Empfindlichkeit von Böden gegenüber Schwermetallen", Hannover.

[12] Salt, C. 1987: Schwermetalle in einem Rieselfeldökosystem, Diss. TU-Berlin. Landschaftsentwicklung und Umweltforschung, Schriftenreihe des Fachbereichs Landschaftsentwicklung der TU-Berlin, 53.

[13] SenGes (Senatsverwaltung für Gesundheit Berlin) 1991: Bewertungskriterien für Bodenkontaminationen auf Spielplätzen, not published.

[14] SenStadtUm (Senatsverwaltung für Stadtentwicklung und Umweltschutz Berlin) 1990: Berliner Schwermetalluntersuchungsprogramm für Klein- und Hausgärten, Landwirtschafts- und Gartenbauflächen, 1979-1990, not published.

[15] SenStadtUm (Senatsverwaltung für Stadtentwicklung und Umweltschutz Berlin) 1991: Ergebnisse der Schadstoffuntersuchungen auf Spiel- und Bolzplätzen, not published.

[16] SenStadtUm (Senatsverwaltung für Stadtentwicklung und Umweltschutz Berlin) 1991a: Richtwerte zur nutzungsspezifischen Risikobeurteilung von Schwermetallgehalten in Böden bzw. bodenartigen Materialien für Berlin, not published.

[17] SenStadtUm (Senatsverwaltung für Stadtentwicklung und Umweltschutz Berlin) 1991b: Ergebnisse des Schwermetalluntersuchungsprogramms, not published.

[18] SenStadtUm (Senatsverwaltung für Stadtentwicklung und Umweltschutz Berlin) 1991c: Kataster der Altlasten- und Altlastenverdachtsflächen, Abt.III.

[19] SenStadtUm (Senatsverwaltung für Stadtentwicklung und Umweltschutz Berlin) (Hrsg.) 1992: Umweltatlas Berlin, aktualisierte und erweiterte Ausgabe 1992, Karte 01.03.3 Blei und Cadmium in Pflanzen, 1:50 000.

[20] SenStadtUm (Senatsverwaltung für Stadtentwicklung und Umweltschutz Berlin) (Hrsg.) 1993: Umweltatlas Berlin, aktualisierte und erweiterte Ausgabe 1993, Karte 01.10 Rieselfelder, 1:30 500.

[21] SenStadtUm (Senatsverwaltung für Stadtentwicklung und Umweltschutz Berlin) (Hrsg.) 1994: Umweltatlas Berlin, aktualisierte und erweiterte Ausgabe 1994, Karte 03.03.3 Emissionen Verkehr 1989, 1:200 000.

[22] Stahr, K. (Hrsg.) 1986: Soilscapes of Berlin (West), in: Mitteilungen der Deutschen Bodenkundlichen Gesellschaft, 50, S.1-204.

[23] TÜV (Technischer Überwachungsverein) (Hrsg.) 1989: Abschlußbericht über die Messungen und Ergebnisse des Immissions-Meßprogramms Berlin (West) 1988, Berlin.