Lead and Cadmium in Soils 1991
Condition and Use of Tested Sites
The 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.
The 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 Analysis
A 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.
Increasing 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.