Inventory and transport of plastic debris in the Laurentian Great Lakes

Plastic pollution in the world’s oceans has received much attention, but there has been increasing concern about the high concentrations of plastic debris in the Laurentian Great Lakes. Using census data and methodologies used to study ocean debris we derive a first estimate of 9887 metric tonnes per year of plastic debris entering the Great Lakes. These estimates are translated into population-dependent particle inputs which are advected using currents from a hydrodynamic model to map the spatial distribution of plastic debris in the Great Lakes. Model results compare favorably with previously published sampling data. The samples are used to calibrate the model to derive surface microplastic mass estimates of 0.0211 metric tonnes in Lake Superior, 1.44 metric tonnes in Huron, and 4.41 metric tonnes in Erie. These results have many applications, including informing cleanup efforts, helping target pollution prevention, and understanding the inter-state or international flows of plastic pollution.

Matthew J. Hoffman, Eric Hittinger, Marine Pollution Bulletin, Volume 115, Issues 1–2, 15 February 2017, Pages 273–281

The article

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Citizen science datasets reveal drivers of spatial and temporal variation for anthropogenic litter on Great Lakes beaches

Accumulation of anthropogenic litter (AL) on marine beaches and its ecological effects have been a major focus of research. Recent studies suggest AL is also abundant in freshwater environments, but much less research has been conducted in freshwaters relative to oceans. The Adopt-a-BeachTM (AAB) program, administered by the Alliance for the Great Lakes, organizes volunteers to act as citizen scientists by collecting and maintaining data on AL abundance on Great Lakes beaches. Initial assessments of the AAB records quantified sources and abundance of AL on Lake Michigan beaches, and showed that plastic AL was > 75% of AL on beaches across all five Great Lakes. However, AAB records have not yet been used to examine patterns of AL density and composition among beaches of all different substrate types (e.g., parks, rocky, sandy), across land-use categories (e.g., rural, suburban, urban), or among seasons (i.e., spring, summer, and fall). We found that most AL on beaches are consumer goods that most likely originate from beach visitors and nearby urban environments, rather than activities such as shipping, fishing, or illegal dumping. We also demonstrated that urban beaches and those with sand rather than rocks had higher AL density relative to other sites. Finally, we found that AL abundance is lowest during the summer, between the US holidays of Memorial Day (last Monday in May) and Labor Day (first Monday in September) at the urban beaches, while other beaches showed no seasonality. This research is a model for utilizing datasets collected by volunteers involved in citizen science programs, and will contribute to AL management by offering priorities for AL types and locations to maximize AL reduction.

Anna Vincent, Nate Drag, Olga Lyandres, Sarah Neville, Timothy Hoellein, Science of The Total Environment, Volume 577, 15 January 2017, Pages 105–112

The article

Application of a comprehensive extraction technique for the determination of poly- and perfluoroalkyl substances (PFASs) in Great Lakes Region sediments

A comprehensive method to extract perfluoroalkane sulfonic acids (PFSAs), perfluoroalkyl carboxylic acids (PFCAs), polyfluoroalkyl phosphoric acid diesters (diPAPs), perfluoroalkyl phosphinic acids (PFPiAs) and perfluoroalkyl phosphonic acids (PFPAs) from sediment and analysis by liquid chromatography tandem mass spectrometry (LC-MS/MS) was developed and applied to sediment cores from three small isolated lakes (Plastic Lake, Lake 442, Lake Tettegouche) and Lake Ontario in the Great Lakes Region. Recoveries of the target compounds using the optimized acetonitrile/sodium hydroxide extraction ranged from 73% to 120%. The greatest concentrations of per- and polyfluorinated alkyl substances (PFASs) were recorded in sediment from Lake Ontario (ΣPFASs 13.1 ng/g), where perfluorooctane sulfonic acid (PFOS) contributed over 80% of the total. Concentrations in Lake Ontario were approximately 1–2 orders of magnitude greater than the more remote lakes subject to primarily atmospheric inputs. Whilst the PFAS contribution in Lake Ontario was dominated by PFOS, the more remote lakes contained sediment with higher proportions of PFCAs. Trace amounts of emerging PFASs (diPAPs and PFPiAs) were found in very recent surface Lake Ontario and remote lake sediments.

Rui Guo, David Megson, Anne L. Myers, Paul A. Helm, Chris Marvin, Patrick Crozier, Scott Mabury, Satyendra P. Bhavsar, Gregg Tomy, Matt Simcik, Brian McCarry, Eric J. Reine, Chemosphere, Volume 164, December 2016, Pages 535–546

The article

Standardized methods are required to assess and manage microplastic contamination of the Great Lakes system [commentary]

Microplastics are products of large plastic item erosion or small (< 1 millimeter) manufactured plastic items. When disposed into waste streams microplastics often end up widely dispersed in both freshwater and marine systems worldwide. Most published reports of microplastics in the aquatic systems to date indicate efforts that are unable to properly sample for microplastics. Advances in the science of environmental monitoring of microplastics are necessary. There is a need to standardize sampling procedures, and notably to adopt the use of “clean” techniques to avoid compromising sample integrity, to insure robust, replicable assessments of microplastic pollution. Reliable, standardized methods are of utmost importance for accurately evaluating the amounts of microplastics in aquatic environments and thus enable the assessment and management of these contaminants.

Michael R. Twiss, Journal of Great Lakes Research, Volume 42, Issue 5, October 2016, Pages 921–925

The commentary

Plastic Debris in 29 Great Lakes Tributaries: Relations to Watershed Attributes and Hydrology

Plastic debris is a growing contaminant of concern in freshwater environments, yet sources, transport, and fate remain unclear. This study characterized the quantity and morphology of floating micro- and macroplastics in 29 Great Lakes tributaries in six states under different land covers, wastewater effluent contributions, population densities, and hydrologic conditions. Tributaries were sampled three or four times each using a 333 μm mesh neuston net. Plastic particles were sorted by size, counted, and categorized as fibers/lines, pellets/beads, foams, films, and fragments. Plastics were found in all 107 samples, with a maximum concentration of 32 particles/m3 and a median of 1.9 particles/m3. Ninety-eight percent of sampled plastic particles were less than 4.75 mm in diameter and therefore considered microplastics. Fragments, films, foams, and pellets/beads were positively correlated with urban-related watershed attributes and were found at greater concentrations during runoff-event conditions. Fibers, the most frequently detected particle type, were not associated with urban-related watershed attributes, wastewater effluent contribution, or hydrologic condition. Results from this study add to the body of information currently available on microplastics in different environmental compartments, including unique contributions to quantify their occurrence and variability in rivers with a wide variety of different land-use characteristics while highlighting differences between surface samples from rivers compared with lakes.

Austin K. Baldwin, Steven R. Corsi, and Sherri A. Mason, Environ. Sci. Technol., 2016, 50 (19), pp 10377–10385

Pelagic plastic pollution within the surface waters of Lake Michigan, USA

During the summer of 2013, a total of 59 surface water samples were collected across Lake Michigan making it the best surveyed for pelagic plastics of all the Laurentian Great Lakes. Consistent with other studies within the Great Lakes, Mantra-trawl samples were dominated by particles less than 1 mm in size. Enumeration of collected plastics under a microscope found fragments to be the most common anthropogenic particle type, followed by fibers, with more minor contributions from pellets, films and foams. The majority of these pelagic plastic particles were found to be polyethylene, with polypropylene being the second most common polymeric type, which is consistent with manufacturing trends and beach survey results. The pelagic plastic was found to be fairly evenly distributed across the entire Lake Michigan surface, despite the formation of a seasonal gyre at the southern end of the lake. We found that an average plastic abundance of ~ 17,000 particles/km2, which when multiplied by the total surface area, gives on the order of 1 billion plastic particles floating on the surface of Lake Michigan. As the majority of these particles are extremely small, less than 1 mm in size, which allows for easy ingestion, these results highlight the need for additional studies with regard to the possible impacts upon aquatic organisms.

Sherri A. Mason, Laura Kammin, Marcus Eriksen and al., Journal of Great Lakes Research, Volume 42, Issue 4, August 2016, Pages 753–759

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Featured Projects, Winter 2016 – Microplastics in the Great Lakes

“Towards establishing a long-term multidisciplinary research platform to assess the impact of microplastics on Laurentian Great Lakes ecosystem health”

Key components of this work have included:

  • Conducting extensive field surveys in summer 2014, including areas near urban areas and downstream of wastewater treatment facilities, to understand the distribution of microplastics in the Great Lakes system;
  • Developing new methods to quantify, or count, plastics in field samples;
  • Improving circulation models to better understand how plastics are transported through the system;
  • Analyzing fish stomach contents to understand the degree of plastic ingestion including particles and fibers (e.g., micro-fleece) in key organisms;
  • Analyzing plastic-associated toxins, to assess potential ecological and environmental health risks from leaching pollutants; and
  • Exploring dynamics of plastic-dwelling microbial communities to understand their potential role in breaking down plastic particles.

Project leaders: Melissa Duhaime (duhaimem@umich.edu) Krista Rule Wigginton, University of Michigan, Dmitry Beletsky, University of Michigan, Cooperative Institute for Limnology and Ecosystems Research

More information about this project here.