On Friday 25 September, Milo de Baat will defend his PhD thesis
Surface waters are contaminated with an increasing diversity of anthropogenic compounds, giving rise to complex contaminant mixtures that can cause serious harm to aquatic ecosystems. However, traditional compound-by-compound based water quality monitoring methods are unfit for the impact assessment of these complex mixtures. Therefore, there is a need for new assessment methods that consider the risks caused by all (un)known bioavailable compounds in the water. The combination of time-integrative sampling methods and effect-based methods that employ living cells or organisms (bioassays) can overcome the limitations of traditional water quality monitoring methods. However, the regular implementation of effect-based methods is still in its infancy, and several scientific challenges in this field remain. Therefore, the present research aimed to fuel the paradigm shift towards new chemical aquatic environmental monitoring methods by providing a scientific basis for the advancement of effect-based water quality assessment.
The present thesis explored the state-of-the-art of effect-based water quality assessment. The refined insights and methodological improvements obtained contributed to an improved strategy for the assessment of the aggregated risk of all bioavailable micropollutants present in the aquatic environment. It was postulated that the full potential of effect-based water quality assessment is achieved when:
i) Sampling methods capture all relevant contaminants from the water.
ii) Environmental samples are transferred as representative mixtures at environmentally relevant concentrations to the bioassays.
iii) The bioassay battery represents all toxicity endpoints relevant to aquatic ecosystem health.
iv) Defined thresholds for the interpretation of bioassay responses are indicative of ecotoxicological risks in the environment.