Experimental study of interception effect by submerged dam on microplastics.

ABSTRACT

Submerged dam can alter microplastic (MP) transport, and act as a sink for MPs. In this paper, we investigated the interception rates of Polyvinyl chloride (PVC) and Polystyrene (PS) by an artificial submerged dam in a flow flume at first, and found that most of the un-intercepted PVC and PS particles by the dam accumulated behind it under the subcritical (Fr < 1) and turbulent (Re > 500) flows. PVC particles behind the dam mainly concentrated within two dam widths, and the concentration of PS particles decreased with the distance behind the dam lengthening. Then, we performed linear regression fitting and Redundancy Analysis (RDA) between the interception rates collected in 162 experiment tests and environmental factors, including flow velocity, distance to dam and MP concentration. The results showed that the interception rate of PVC and PS particles increased with the distance to dam lengthening, but decreased with the flow velocity and MP concentration heightening. RDA revealed that the interception rate was influenced by flow velocity, distance to dam, and MP concentration from the most to the least. Our findings are believed to contribute to understanding the mechanism of the interception effect of submerged dam on microplastics.