Eu risk assessment
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- Figure 3.1.9 26
- Table 3.1.9 77: Country-specific 10 th , 50 th and 90 th percentiles of Pb-background levels in the soil compartment
- Country Soil compartment (mg Pb/kg dry wt)
Terrestrial compartmentMeasured Pb concentrations in soil are presented in Table 3.1.9-18. Little or no data were found for southern European countries. The soil Pb concentrations in areas away from point sources range between 0.6 and 460 mg kg-1dw and most concentrations are found in the 15-40 mg/kg dry wt range. Figure 3.1.9-11 illustrates the concentration ranges that are listed in the table 3.1.9-18. The average of all survey means, medians or geometric means (of min-max) is 27.6 mg/kg dry wt and the average of 90th percentiles is 50.6 mg/kg dry wt. Only few studies report 10th percentiles of measured Pb concentrations in soils away from point sources. The average of these 10th percentiles is 18 mg/kg dry wt. This value corresponds well with the 10th percentile of ambient Pb concentrations away from point sources (i.e. all survey means, medians or geometric means).  
Figure 3.1.9 26 Measured concentrations of Pb in soils in Europe. Points are averages, medians or geometric means (of min-max) 10th or 90th percentiles of all European surveys listed in Table 3.2.5.3-35. Full points give the means of corresponding ranges. Observations near point sources and industrial activities are excluded. Reported average Pb concentrations in soils located away from point sources range between 16 and 41 mg/kg dry wt. A typical average Pb concentration (ambient Pb concentration) in soils located away from point sources is 28 mg/kg dry wt. This concentration is higher than most median soil Pb concentrations of the different surveys but corresponds to the average of all survey means, medians or geometric means. Table 3.1.9 76 total lead concentrations in soils
Background levels of Pb in the terrestrial environment Similar to what has been performed for the water and sediment compartment, the FOREGS monitoring program has collected soil samples thhoughout Europe in order to establish reliable baseline levels for various ions, including lead. Soil samples collected in the FOREGS-program had to reflect variations in the geogenic composition of the uppermost layers of the Earth's crust. Because of this, it was important to avoid soil sampling at locations that had visible or known contamination. Priority for site selection was given to: forested and unused lands; greenland and pastures; and non-cultivated parts of agricultural land (in very special cases, where residual soil could not be found). Residual soil samples were collected at locations from small, second order, drainage basins (<100 km2) at a suitable site above its alluvial plain and base of slope, where alluvium and colluvium are respectively deposited. Residual soil developed either directly on bedrock or on till was accepted. Residual soil from areas with agricultural activities was avoided, since the top soil is usually affected by human activities. Colluvium or alluvium was not accepted as representing parent material. Each residual soil sample was a composite of 3 to 5 sub samples collected from pits located at a distance of 10-20 metres from each other. Top soil samples represented the 0-25 cm top layer, excluding material from the organic layer where present. The residual soil sample represents the dominant residual soil type of the selected catchment basin. Minimum distance to roads was 10 m and to ditches 5 m. Living surface vegetation, fresh litter, large roots and rock fragments (stones) were removed by hand. The total number of analysed top soil samples was 843. Pb-levels ranged between <3 and 886 mg Pb/kg dry wt, with a 50th percentile (European median) of 15 mg Pb/kg dry wt and a 90th percentile of 38.2 mg Pb/kg dry wt). Table 3.1.9-19 presents the country-specific background levels of Pb in the terrestrial compartment that were determined with the raw data from the FOREGS program. Country-specific_10_th_,_50_th_and_90_th_percentiles_of_Pb-background_levels_in_the_soil_compartment'>Table 3.1.9 77: Country-specific 10th, 50th and 90th percentiles of Pb-background levels in the soil compartment
Typical (50th percentile) country-specific background levels for the terrestrial compartment range between 2.5 mg/kg dry wt (Denmark) and 29.0 mg/kg dry wt (Slovenia).
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