Sediment quality assessment in Switzerland: spatial and temporal patterns of contamination

A validation or adaptation of the TEC-PEC values for Switzerland is recommended before SQG can be implemented. Background concentrations can be established on a regional scale when a broad database is available, e.g. 5%-percentile of data. Else the FOREGS (Forum of the European Geology Surveys; www.gsf.fi/publ/foregsatlas) can be used as a rough indicator. A tiered approach that includes an initial comparison against TEC-PEC values and a subsequent consideration of background/natural metal concentrations can serve as a preliminary framework until SQG are implemented in Switzerland. Harmonisation of sampling and pre-treatment methods is required.