Title : Marine bioremediation of port sediment: Investigation of tributyltin degradation using active nautical depth
Active Nautical Depth (AND) is a promising sustainable method to replace or reduce dredging need and mitigate the problems associated with siltation in ports and harbours. It consists of mixing and aerating the sediment in situ, turning it into a navigable fluid mud. AND has many benefits, for example the reduction of carbon emission or spreading of contaminants happening during dredging, making it an cost effective and environmental friendly method for sediment management. But AND could be even more beneficial: changing the physicochemical properties of the mud promotes the growth of aerobic microorganisms which have the potential to degrade harmful contaminants that are commonly found in ports and harbours, such as tributyltin.
Tributyltin is a previously widely used antifouling compound, now globally banned as a result of its high toxicity, but still of actual concern as it is very persistent in anoxic sediment where it can remain for decades. The elimination of TBT from the environment mainly occurs through biodegradation by aerobic organisms, but this phenomenon remains unclear.
This study therefore aims to better understand the factors controlling tributyltin biodegradation in sediment. This is done by conducting microcosm experiments under different environmental scenarios and comparing TBT degradation rates. We also aim at obtaining a better comprehension of the microbial community implicated by the use of an innovative approach for bacterial isolation, the iChip.
The results will be obtained by February 2020, we expect higher degradation rates under higher temperature, aeration exposure and agitation frequency (which will influence aeration) as TBT degradation is known to be performed aerobically and as increasing temperature is known to increase microbial activities.
These results could be used to optimize AND application, by running it during warmer seasons and adapting the duration of sediment exposure to the air before its pumping back to sea bottom. Overall, the results of this study will extend our knowledge on TBT degradation in marine sediment.
Presentation Learning Outcome
- The audience will learn about an innovative method which aims at combining sediment management and remediation
- The study described in this presentation will provide the audience with insights on the optimal conditions of application for this technology
- This research is only a preliminary work investigating the potential remediation of one contaminant but it opens the way to numerous research projects, especially to consider the remediation of other contaminants commonly found in ports. The audience may therefore be interested in future work and collaborations.