A river with chemically polluted sediments at its bottom is missing a crucial habitat. However, until now there has been no uniform method for monitoring the quality of sediments. On behalf of the Federal Office for the Environment, experts from the Ecotox Centre and Eawag have now developed a proposal for this.
One of the aims of the Swiss Water Protection Ordinance is to ensure that sediments do not contain persistent chemicals or accumulate substances that have a harmful effect on organisms. This is because these compounds can deteriorate surface water quality. However, Switzerland still lacks a uniform strategy for the assessment of sediment quality. The Ecotox Centre has now developed such a strategy during 6 years in exchange with the cantonal water protection agencies, the VSA as well as experts from Eawag and other research institutions.
From sampling to assessment
In the expert report that has just been published, a robust strategy for monitoring and assessing the quality of sediments on the basis of their chemical status is presented. The strategy includes procedures for sampling and sample pre-treatment for chemical analysis. In addition, it contains a substance list proposed for monitoring campaigns, sediment quality criteria (EQSsed) for these pollutants, and a multi-level assessment system that is based on the modular stepwise procedure. The strategy is designed for routine use and builds on methods already used in the cantons.