Impacts on Soils Related to Industrial Activities: Part IV—Effects of Air Pollutants on the Soil

Summary

In ecological terms air pollutants are acids (and their precursors), potential toxins and nutrients. Their effects on soils are therefore very complex. Owing to the filtering effect offorest canopies, deposition of air pollutants is usually much higher in forests than in areas of low vegetation (pastures and arable land). Soils act either as an inert matrix (e.g. for NaCl) or as sinks (e.g. for heavy metals in neutral soils) or sources (e.g. for acids: equivalent amounts of cations to the number of protons can be leached out) for air pollutants. In non- tillage ecosystems of low cropping intensity (e.g. in forests and heathland) deposited heavy metals accumulate in the surface soil horizon. As a result of acid deposition, forest soils in Central Europe have already lost most of their mobilisable nutrient reserves and are now acid below the rooting zone. Acidification takes place within the seepage layer, endangering the quality of the water from forested areas. The process is not fully understood, and a drastic reduction in emissions of S0₂, N0_x, heavy metals and organic micropollutants is recommended as a regulatory measure.