Contribution short abstract:

Port dredging, a necessary form of harbour maintenance, stirs up contaminated sediments. This paper examines the ethical, epistemological, and infrastructural tools mobilized to reduce toxic exposure to "legacy sediments" in the Bay of Marseille.

Contribution long abstract:

Port dredging, a necessary form of harbor maintenance, stirs up contaminated sediments. The city of Marseille and the Aix-Marseille-Provence metropolitan government regularly carry out dredging operations in the Mediterranean to keep ports functional. As early as 2001, environmental NGOs reported that dangerous contaminants scattered in the wake of dredging. Along with silt, sand, and marine biota, dredgers unearthed toxic matter or “legacy sediments.” In the port of Marseille, concentrations of contaminants were 37 times higher than official threshold values. “Toxic elements” in the nearshore waters of Marseille are not inert: once suspended and taken up by littoral drift, they can get deposited in the city’s shallow lagoons and on beaches. Here, hobby boaters anchoring in the bay or recreational swimmers further stir up contaminated sediments. Together, these more or less innocuous acts have turned the Bay of Marseille into a “toxic site” or “negative commons” (Müller and Balayannis 2024), with devastating consequences for marine species and various health risks for humans. In some ports, sediment layers have become so laced with heavy metals that dredging is deemed impractical. How do residents, planners, and experts deal with this “toxic common” beyond repair (Müller 2021)? What are the ethical, epistemological, and infrastructural tools mobilized to intervene at these sites? And what does dredging, as a form of purging, have to do with the legacy of industrial urbanization and long-term liability for oceanic pollution? What other ways to coexist with sediments “in the fraught muddiness of the ongoing present” (Anand 2023:701)?