Sediment toxicity identification evaluation: The application of passive sampling and passive dosing techniques

In aquatic environment, hydrophobic organic contaminants preferentially deposit into sediment. Over time, sediment becomes an important sink for these contaminants, posing a hazard to aquatic organisms. Therefore, the... [ view full abstract ]

In aquatic environment, hydrophobic organic contaminants preferentially deposit into sediment. Over time, sediment becomes an important sink for these contaminants, posing a hazard to aquatic organisms. Therefore, the assessment of sediment quality is one of the vital tasks for understanding the risk of these contaminants. It is well accepted that bioavailability of sediment-bound contaminants is affected by many factors, such as sediment characteristics, chemical properties, and chemical-sediment contact time, which makes the bulk sediment concentration a poor indicator for sediment toxicity. Thus, a variety of methods have been developed for estimating contaminant bioavailability in recent decades. As a more relevant dose metric compared to bulk sediment concentration, the freely dissolved concentration in sediment pore water (Cfree) reflects the exposure and the bioaccumulation potential of contaminants to organisms. By incorporating Cfree into the dose-response relationship, exposure indicated by Cfree is directly linked to adverse effects. Additionally, passive dosing has been recently introduced as a replacement of solvent dosing during aquatic toxicity testing in order to maintain constant water concentrations. Through the equilibrium partitioning of chemicals within dosing systems, chemical concentrations in water could be stabilized and monitored by quantifying chemical concentration in the polymers. To conduct toxicity testing with passive dosing systems is another approach to incorporate the bioavailability into sediment toxicity assessment. In this presentation, two case studies will be used to demonstrate the applications of bioavailability-base sediment toxicity testing.