To Örebro University

Climate change is driving extreme weather patterns, leading to prolonged droughts and more frequent intense precipitation events. These environmental changes will impact aquatic systems by altering essential water quality parameters such as temperature, redox potential, pH, suspended solids and organic matter, which influence pollutant solubility and determine ecosystem health as well as drinking water production. In this context, sediments play a crucial role as they represent both a sink and source of pollutants. Therefore, sediment toxicity testing is essential for accurate environmental risk assessments. However, there remains a gap regarding comprehensive sediment testing ap-proaches that integrate multiple biomarker responses.

The SEASON project uses an interdisciplinary approach combining strategies of environmental toxicology, analytical chemistry, andhydro geochemistry. The aim is to develop conceptual models for evaluating, understanding and predicting the impact of climate change effects on the fate, bioavailability, and toxicity of pollutants in the aquatic environment. This project focuses on risks associated with sediments contaminated by organic and inorganic pollutants, specifically metals and PFAS (per- and polyfluoroalkyl substances). By studying factors such as temperature, pH, microbial communities, and sediment-water interactions, the project seeks to understand how different climate change aspects affect pollutant behavior in aquatic ecosystems.

The project consists of four sub-projects. Three investigate different chemical groups and mixtures under varying water conditions, using zebrafish (Danio rerio) as the main model organism. These studies will include in vitro and in vivo assays, microcosm experiments, microbiome studies and chemical analyses. The fourth subproject will integrate the results to develop a predictive model for sediment risk assessment.

Sediment contact assays will be performed to evaluate the effects of contaminated samples on zebrafish embryos by measuring teratogenicity, developmental toxicity, behavioral changes, and gene expression. In microcosm studies, we will vary pH and mimic increased precipitation events to assess pollutant toxicity in adult zebrafish including sex-related toxicity differences, reproduction, and behavior. Effect-directed analysis (EDA) will be used to identify key toxicants in the samples. Microbiome analysis using metagenomic sequencing will focus on how contaminated sediments alter bacterial communities, which in turn can affect pollutant distribution and bioavailability. Chemical analyses will quantify PFAS, metals, and their speciation throughout the study. Ultimately, the project will integrate these data to develop models that increase our understanding of the impact of climate change on sediment contamination and aquatic ecosystem health.