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- Forest soil (1) (entfernen)
While organic pollutants have been extensively studied in urban and agricultural areas, data from forested regions are relatively rare.
Within the framework of a forest soil inventory in Germany polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB) and organochlorine pesticides (OCP) were analyzed in 1500 soil samples taken from 3 soil horizons at 447 sites. An analytical protocol was developed and validated for the simultaneous extraction and measurement of all analytes in humic rich soil at trace level range. It included pressurized liquid extraction (PLE) and a two step cleanup procedure consisting of gel permeation chromatography (GPC) followed by solid phase extraction (SPE). Quantification was carried out using gas chromatography combined with mass spectrometry (GC-MS). In line with the monitoring campaign a comprehensive quality assurance concept was implemented to guarantee constant analytical measurement conditions for two years. The protocol is applicable for field laboratories with a high level of automation and for analyzing high sample amounts.
At most sampling sites pollutant concentrations gradually decrease with depth. Only few spots showed highest concentrations in the upper mineral soil. In the O-horizon the sum concentrations of 16 PAHs range from 104 to 14.000 µg/kg, of 6 PCBs from <1 to 106 µg/kg and the sum of DDT and metabolites range from <1 to ca. 4.000 µg/kg.
The observed concentration of PAH, PCB and OCP reflect an ubiquitous background contamination at most sites. Relatively high concentrations of PAH and PCB are related to industrial areas and peak concentrations only of PAH are associated with open cast mining of brown coal areas. The spatial distribution of the contents of DDT and metabolites in German forest soils can clearly be attributed to historic application. A contribution of ubiquitous background pollution derived from long-range atmospheric transport is likely for some compounds in the studied area, e.g., DDT in the western part of Germany. The results generally reflect the distribution of POPs in densely populated and industrialized countries located in temperate regions].