| Popis: |
Persistent organic substances can have harmful effects on humans and on the environment. Nationwide studies of organic substances on forest sites are scarce. Therefore, the sampling area of the second National Forest Soil Inventory (NFSI) with the BIOSOIL grid was used to investigate the contents, stocks, and spatial distribution of persistent organic substances in forest soils. The investigated substances were polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB), dichlorodiphenyltrichloroethane and its metabolites (DDx), hexachlorobenzene (HCB), polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF), and dioxin-like polychlorinated biphenyls (dl-PCB). To our knowledge, this is the first study to show stocks of organic substances in forest soils on a nationwide basis. The results showed that the organic substance stocks were not dependent on forest type for the investigated substances, except for PCB. This indicated that other factors than forest type explained the differences in total stock amounts across Germany, e.g. deposition or vicinity to emission sources. The content of the investigated organic substances in German forest soils seemed to be generally low. This was underpinned by the values of PAH and PCB, which were lower than the precaution values prescribed in German soil protection legislation (BBodSchV). However, soils store organic substances over long periods. Additionally, deposition of organic substances stemming from industrial sources might accumulate in soils in the future and become a problem. It is therefore recommended to find appropriate measures to reduce these depositions. Furthermore, soil samplings to study the development of organic substances contents under forest should be conducted. In this study, a greater share of the variance was explained with nonlinear regression compared to linear methods. It seems therefore reasonable to consider nonlinear trends in the evaluation of data from future studies. The outcome will improve models that forecast the distribution of organic substances in forest soils. Eventually, the results can contribute to further develop background, precaution, trigger, and action values in the German soil protection legislation. |
