Protective effect of the top layers on the surface

The map contains an assessment of the protective effect of the top layers, divided into the three categories “unfavourable”, “medium” and “favourable”. The decisive criterion for the allocation and spatial delimitation of individual area units was the petrographic nature (bind/non-binding) and thickness demonstrated by drilling (divisions: < 5 m, up to 10 m, > 10 m). In the marches and lowlands of the west coast, specific sediment properties favour the retention capacity of pollutants there. This was also taken into account in the assessment of the protective effect.