Prediction of the long term accumulation and leaching of zinc in Dutch agricultural soils: a risk assessment study

A dynamic model was used to predict future soil Zn concentrations at ongoing present Zn inputs until steady state is reached (Predicted Effect Concentrations at steady state or PEC steady state) in comparison to the Predicted No Effect Concentration (PNEC) of Zn. The main aim of this report is to evaluate whether the current load of zinc to soils in different forms of land use (arable land, pasture) and soil types leads to an exceedance of the PNECs, and if so at what time scale. Results show that at present there is hardly any exceedance of the PNEC of zinc in the Netherlands. The percentage of plots where PEC steady state will exceed the PNEC is estimated at approximately 50% when using current (year 2000) inputs and this number appears to be very robust. The predicted time period to reach the PNEC for zinc is on average approximately 250 years for grassland and 650 years for arable land when using current inputs. This number is however very uncertain. When respecting the N legislation, this time period increases to approximately 600 years for grassland and 700 years for arable land.