Groundwater pollution due atmospheric deposition was investigated
applying a mass balance concept at the catchment scale. A simple mass
balance (input/output) was used to quantify overall natural attenuation of
heavy metals (Zn, Cu, Ni, Cu, Pb, and Cd) and phthalates (DMP, DBP and
DEHP) in two forested catchments in SW Germany (Seebach and
Denzenberg valley). Decreasing concentrations from rainwater to
groundwater, sorption rates of mostly more than 60% comparing input and
output fluxes and preferential accumulation in the upper soil horizon
confirmed the atmospheric origin of the heavy metals and phthalates
investigated as well as the role of soils as a major sink for these pollutants.
Sorption under equilibrium conditions would lead to lower groundwater
concentrations than monitored, implying an additional non-equilibrium
transport of the pollutants through the unsaturated zone by preferential
flow. We recommend catchment area studies to assess the long-term risk
of groundwater pollution due to diffusive atmospheric deposition of
contaminants with high persistence
