[en] Objectives: - Determine whether a Zone of Influence (ZOI) develops in contaminated sediment deposited over active caps; - Evaluate the effects of bioturbation on development of the ZOI; - Improve understanding of the relationships among surface sediment recontamination, remediated contaminated sediments, and biological receptors. Hypothesis: A Zone of Influence (ZOI) will develop in contaminated sediment deposited over active caps and bioturbation will enhance the remedial effectiveness. The effectiveness of the caps will be assessed by evaluating the spatial extent and chemical characteristics of the ZOI that develops in the sediment that accumulates over the caps. Bioturbation may be important in ZOI development by mixing accumulating sediments with cap materials. This study will include mesocosms both with and without bioturbating organisms. Biouptake in caged organisms within the mesocosms will be compared with results from diffusive gradients in thin films (DGT) probes, which have the unique ability to detect fine vertical gradients in metal availability and speciation. Key Points: - Asian Clams were selected to create bioturbation in the experiment; - California Blackworms were selected to test toxicity and bioavailability; - Each mesocosm will receive 0.5 mL/min of synthetic fresh water; - Properties of the synthetic fresh water were measured and compared to Nanopure DI water; - Contaminated sediment will be added to each mesocosm throughout the experiment to determine whether a ZOI develops between the sediment and active cap; - Metal bioavailability and ZOI formation will be compared between mesocosms with and without bioturbation