Plastic remobilization by dam removal and chemical effects.

BLETTLER MARTIN

Tours

Workshop; Ecohydraulics and dam removal, 3rd meeting; 2019

LE STUDIUM, Institute for advanced studies, Loire Valley

In-stream barriers, however, have not yet been adequately investigated as additional sources of spatial variability, though they have been mentioned as likely sinks for light plastic particles (Lebreton et al., 2017; Mani et al., 2015). A handful of existing longitudinal surveys published on microplastic concentrations along rivers containing weirs or dams point to the possibility that some microplastic settling may be occurring within impoundments (Mani et al., 2015; Zhang et al., 2015, 2017). Settling is likely facilitated by decreased buoyancy due to biofilm accumulation on plastics' surfaces, as evidenced in wastewater treatment plants (Carr et al., 2016) and experimentation (Kaiser et al., 2017; Lobelle and Cunliffe, 2011; Morét-Ferguson et al., 2010). The presence of microplastics in sediments worldwide supports settling as one fate for microplastics, but the presence of microplastics in sediment found behind dams has not yet been directly investigated (Castañeda et al., 2014; Di and Wang, 2018; Horton et al., 2017; Klein et al., 2015; Rodrigues et al., 2018; Zhang et al., 2017). The hypothesis that dams effectively reduce the microplastic concentrations transported along rivers by trapping plastics in sediments within reservoirs.