Microplastic pollution in freshwater ecosystems is an emerging topic. Primary microplastics are designed to be small (e.g., microbeads, pre-production nurdles) and secondary microplastics result from photo and mechanical degradation. The origin of primary microplastics is marine debris and personal care products, whose small size evades wastewater treatment plant processing. Many organisms mistake microplastics for food and the particulates biomagnify up the food chain. There is growing concern that microplastic particulate has potential to adsorb chemicals and pathogenic bacteria, leaching plasticizers up the food chain. We quantified and characterized microplastics derived from 24-hr samplings of wastewater treatment plant (WWTP) post-treatment effluent, as well as long-term monitoring (LTM) zooplankton samples in the Lake Champlain watershed. We quantified whether these particulate were biomagnifying within lake organisms. Using wet peroxide oxidation we digested post-treatment WWTP effluent (Plattsburgh and Ticonderoga NY; St. Albans and Burlington, VT) in the Lake Champlain basin during 2015-16.
Across all sites, the dominant microplastics were characterized as fragments and fibers. Of samples processed, the fragment:fiber percentages have varied by plant, specifically Plattsburgh (51:23%), Ticonderoga (44:40%), St. Albans (67:8%), and Burlington (69:18%). Over 1000 microplastics were identified from a 24-hr sampling session, showing the potential of WWTP to be a significant source. Simultaneously, a total of 2265 LTM samples collected between 2010-2015 were processed. Pre-production rubber pellets (nurdles) were observed in samples from 2012-2015, twice as many were found in 2012-13 as compared to 2014-15 and microplastics were noted. Concern for the biomagnification of microplastics culminated in a trophic study. All organisms (n=411) representing invertebrates (n=257), 14 fish species (n=139), and double-crested cormorants (n=15) were processed in a manner similar to WWTP samples. Microplastic biomagnification was noted and abundance varied across species. Average microplastic abundance in invertebrates, fish, and cormorants was 0.05, 1.91, and 22.93, respectively and the majority were fibers. This research represents the first of its kind to quantify and map the microplastic pollution problem in Lake Champlain. Results from this study will inform wastewater treatment plant operators, land owners, Fish and Wildlife managers, lake stewards, and governmental officials of the threats microplastics pose to aquatic organisms.