Microplastics (MPs) are &lt; 5 mm sized plastic particles that are now ubiquitous in oceans and rivers. A combination of physical, chemical, and radiative (UV light) processes degrade large plastic materials into small fragments (MPs and even smaller nanoplastics) and leach chemical by-products. Once small (&lt; 5 mm), MPs become highly mobile, can adsorb other pollutants (such as DDT, PCBs, dioxins), and can be ingested by biota where MPs can have direct effects on an organism or bioaccumulate. The study of MPs began in the 1970s, but has seen a recent resurgence after 2004. During the past 15 years, studies of MPs have focused on marine environments with less than 4% of studies focused on freshwater systems. More recent work is showing that MPs in freshwater systems can be found in concentrations just as high as in marine environments although much less is known about their transport, fate, and affect in freshwater systems. Of the MPs studies in freshwater systems, the focus has been on looking for MPs in sediments on the bed of rivers and streams. MPs are small, lightweight particles that should behave most similarly to non-cohesive fine sediment and therefore follow similar transport and deposition pathways and processes. As such, one should expect to find much higher concentrations of MPs in floodplains than on the bed of rivers and streams because this is where most fine sediment deposits. In this research, soil samples were collected downriver of plastic point sources including sediments and floodplains. MPs were separated from the soil by size and density. Larger amounts of MPs were found in the floodplains. The average particle size and distribution suggested a variety of degradation processes including mechanical and photo-oxidative. Fourier transform infrared (FTIR) spectroscopy indicated that the MPs contained depolymerized and oxidized polyolefins and other commonly found packaging polymers.

Fate of microplastics in inland waterways

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.