Interpreting the extent and characteristics of microplastics pollution in Maine freshwater streams to guide a holistic mitigation strategy

Microplastics on hand

Location: University of Maine
Sponsor: Maine Water Resources Research Institute 2022 (104b)

Widespread occurrence of miniscule plastic fragments (i.e., microplastics) in natural waters around the world is an imminent threat to ecosystem and public health. In Maine, microplastic pollution is especially concerning because the state is one of the largest producers of fish and shellfish in the nation and seafood consumption could contribute to microplastic ingestion. The pollution of Maine waters could also be detrimental to the abundance of sensitive ecosystems influenced by freshwater flows, eventually impacting the state’s coastal economy. In addition, the sources and the perception of risks associated with microplastics is not uniform across communities in the region. Many citizens remain unaware of the potential threats caused by microplastics in the food chain and drinking water sources, elevating the demand for information related to the presence and implications of microplastic pollution.

This project responds to these concerns and demands by focusing on microplastics carried in freshwater stream flows. Drawing on a transdisciplinary team approach, this study will: 1) detect microplastic pollution and describe the pollutant characteristics (e.g., particle dimensions, composition, mobility, concentration) in rural and urban freshwater streams in Maine; 2) interpret the sample collection and analysis outcomes (e.g., origins, chemical composition); and 3) communicate outcomes in a three-phase stakeholder engagement process to frame action-oriented mitigation options. The overarching vision of the project is to develop foundational knowledge for the detection, interpretation, and communication of microplastic pollution problems in Maine’s freshwater streams.

There are many sources of microplastics in freshwater streams, including wastewater treatment plant effluents, surface runoff after rainfall events (e.g., tire chips, artificial turf, other plastic debris), and direct input from human activities (e.g., navigation, fishing, recreation, littering). The team’s preliminary efforts revealed the presence of microplastics in more than 70% of collected water samples in Maine. This outcome aligns with published work from different regions of the world. Our approach is to perform a systematic sampling campaign to capture a range of watershed, hydrologic, and seasonal conditions. The description of the problem will focus on the conditions in which microplastic pollution problems are detected and the types of pollutants that are present. The project will leverage existing measurement infrastructure managed by team members and the USGS at pre-established monitoring stations (Smith), geospatial surface coverage data organized by team members in the region (Smith), ongoing harmful algal bloom sampling infrastructure (Ross) and federally funded microplastic analysis lab facilities (Apul). The project will also optimize use of a stakeholder guided risk assessment framework under development for other emerging pollutants in collaboration with Maine Department of Environmental Protection (Noblet). This capacity will be combined with expansion into additional locations and communities to capture conditions representative of the region (Zollitsch).

Team Leader:

  • Onur Apul, Assistant Professor, Civil & Environmental Engineering, University of Maine

Team Members:

  • Lauren Ross, Assistant Professor, Civil & Environmental Engineering, University of Maine
  • Sean Smith, Associate Professor, Earth & Climate Sciences, University of Maine
  • Brenda Zollitsch, Bangor Area Stormwater Group
  • Caroline Noblet, Associate Professor, Economics, University of Maine