The objective of the project is to develop assessment principles to derive test and action values for soil-relevant pollutants and groups of pollutants in soil/plant dynamics, not covered at present in the Federal Soil Protection and Contaminated Sites Ordinance (BBodSchV). The investigated groups of substances primarily include per- and polyfluoroalkyl substances (PFAS) and also polybrominated diphenyl ethers (PBDE).
In addition to a literature review, extensive container experiments and field trials are performed with different test soils and crops (spring wheat, soya and ryegrass). The samples are analysed using modern and innovative environmental analysis methods, supplementing substance-specific analyses with summary parameters. Finally, soil-to-crop transfer factors are established for the tested varieties, the potential risk from PFAS (and precursors) and PBDE to the soil is estimated, and a need for further research is demonstrated with regard to possible test and action values.
The following questions are relevant:
- To what extent does transfer take place of PFAS from soil to plant or specific plant parts?
- Can suitable indicator substances be identified for this transfer?
- To what extent can all the single substances analysed here, explain the overall contamination of soil and plants with PFAS (measured using surrogate parameters)?
- Which sampling strategy and analytical methods should ideally be used in future to investigate a soil-to-plant transfer of PFAS?
- Do the existing findings provide an adequate technical foundation to derive test and action values?
- How relevant are PBDE to soil protection and what findings are available on their presence and behaviour, particularly on their uptake in plants?