Soil as a filter for groundwater quality

The filtering function of soil is an important ecosystem service for groundwater and surface water protection. The efficiency of soils as a filter depends on the behaviour of pollutants in the soil and the hydrological transport processes. This paper aims to identify knowledge gaps in processes influencing pollutant behaviour in soils and their potential transport to groundwater.Currently most soil-filter function research is approached from two disciplines, one originating from agronomical/environmental sciences; one from more fundamental hydrological process research. Combining insights and approaches from both disciplines through collaboration could lead to better understanding of this complex system and enhance assessments of management strategy changes, both over the long term as well as in different climatic settings.

► A synthesis of case studies on the impact of land management and soil characteristics on the soil filtration and buffer function.
► Research on pollutant behaviour and soil hydrology should be integrated.
► Influence of climate, soil type and management practices on soil filter function needs more research.
► Integration of field and laboratory studies with modelling studies is important.
► Comprehensive parameterisation based on field measurements should be aimed for.