Methodology for sediment quality assessment

The strategy for assessing sediment quality in Switzerland includes sampling and sample treatment procedures for chemical sediment analysis in streams and lakes, in relation to micropollutant loads. In addition, it contains a list of substances proposed for monitoring. Ecotoxicological sediment quality criteria (EQSsed) have been developed for these substances. The assessment system proposed in the strategy is based on the Modular Stepwise Approach. The strategy is designed for routine use in water monitoring and builds on methods already used in the cantons.

Note: This publication is not an enforcement aid of the Confederation but an expert report.

Recorded parameters:

A list of 20 substances, including metals, pesticides, and pharmaceuticals, is proposed for regular sediment monitoring. However, this list is not suitable for all cases and should be adapted depending on the type of water body, the sources of pollution present and the objectives of the investigation.

Evaluation:

The assessment is carried out in a two-level approach. Level 1 consists of the chemical analysis of the substances and the subsequent comparison of the measured concentrations with sediment quality criteria (EQSsed). Five quality classes are used for evaluation. If the EQSsed are exceeded, adverse effects on sediment organisms cannot be excluded. If possible, a more detailed, site-specific risk assessment (level 2) should be conducted in this case. Level 2 is listed in the report, but detailed clarifications are case-specific and must be discussed with experts.