Assessment of floating plastic debris in surface water along the Seine River

• Floating debris were studied using a large network of floating retention booms.
• Plastic debris represented 0.8–5.1% of total debris by weight intercepted by booms.
• Between 22 and 36 tons of floating plastic debris were intercepted annually.
• The mass of floating plastic debris per inhabitant per year is between 1.3 and 8.2 g.

This study is intended to examine the quality and quantity of floating plastic debris in the River Seine through use of an extensive regional network of floating debris-retention booms; it is one of the first attempts to provide reliable information on such debris at a large regional scale. Plastic debris represented between 0.8% and 5.1% of total debris collected by weight. A significant proportion consisted of food wrappers/containers and plastic cutlery, probably originating from voluntary or involuntary dumping, urban discharges and surface runoff. Most plastic items are made of polypropylene, polyethylene and, to a lesser extent, polyethylene terephthalate. By extrapolation, some 27 tons of floating plastic debris are intercepted annually by this network; corresponding to 2.3 g per Parisian inhabitant per year. Such data could serve to provide a first evaluation of floating plastic inputs conveyed by rivers.