Sherri A. Mason’s research while affiliated with Pennsylvania State University and other places

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Publications (24)


Proportion of data sharing statements (A) overall and (B) annually between 2006 and 2021 in the peer-reviewed publications. Numbers displayed on the bars in panel b refer to the yearly number of data sharing statements.
Data dissemination methods indicated in the data availability statements of the articles analysed in this study.
(A) Proportion of microplastic publications found in Web of Science between 2013 and 2021 that have a dataset in an open access repository; (B) Number of data sets in open access repositories during the same period along with the annual number of peer-reviewed microplastics articles published.
Yearly (bar graph) and cumulative (pie chart) distributions of microplastics datasets uploaded to open access repositories between 2013 and 2021.
Geographical distribution of microplastics datasets according to sample provenance. Note that the marine environments and estuaries section includes beaches, coastal areas, seas, and trenches. Unknown means that there were not sufficient metadata in the dataset to determine the location.

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Current State of Microplastic Pollution Research Data: Trends in Availability and Sources of Open Data
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June 2022

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1,285 Reads

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54 Citations

Tia Jenkins

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Bhaleka D. Persaud

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The rapid growth in microplastic pollution research is influencing funding priorities, environmental policy, and public perceptions of risks to water quality and environmental and human health. Ensuring that environmental microplastics research data are findable, accessible, interoperable, and reusable (FAIR) is essential to inform policy and mitigation strategies. We present a bibliographic analysis of data sharing practices in the environmental microplastics research community, highlighting the state of openness of microplastics data. A stratified (by year) random subset of 785 of 6,608 microplastics articles indexed in Web of Science indicates that, since 2006, less than a third (28.5%) contained a data sharing statement. These statements further show that most often, the data were provided in the articles’ supplementary material (38.8%) and only 13.8% via a data repository. Of the 279 microplastics datasets found in online data repositories, 20.4% presented only metadata with access to the data requiring additional approval. Although increasing, the rate of microplastic data sharing still lags behind that of publication of peer-reviewed articles on environmental microplastics. About a quarter of the repository data originated from North America (12.8%) and Europe (13.4%). Marine and estuarine environments are the most frequently sampled systems (26.2%); sediments (18.8%) and water (15.3%) are the predominant media. Of the available datasets accessible, 15.4% and 18.2% do not have adequate metadata to determine the sampling location and media type, respectively. We discuss five recommendations to strengthen data sharing practices in the environmental microplastic research community.

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Global meta-analysis of microplastic contamination in reservoirs with a novel framework

November 2021

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367 Reads

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120 Citations

Water Research

Microplastic contamination in reservoirs is receiving increasing attention worldwide. However, a holistic understanding of the occurrence, drivers, and potential risks of microplastics in reservoirs is lacking. Building on a systematic review and meta-analysis of 30 existing publications, we construct a global microplastic dataset consisting of 440 collected samples from 43 reservoirs worldwide which we analyze through a framework of Data processing and Multivariate statistics (DM). The purpose is to provide comprehensive understanding of the drivers and mechanisms of microplastic pollution in reservoirs considering three different aspects: geographical distribution, driving forces, and ecological risks. We found that microplastic abundance varied greatly in reservoirs ranging over 2-6 orders of magnitude. Small-sized microplastics (< 1 mm) accounted for more than 60% of the total microplastics found in reservoirs worldwide. The most frequently detected colors, shapes, and polymer types were transparent, fibers, and polypropylene (polyester within aquatic organisms), respectively. Geographic location, seasonal variation and land-use type were main factors influencing microplastic abundance. Detection was also dependent on analytical methods, demonstrating the need for reliable and standardized methods. Interaction of these factors enhanced effects on microplastic distribution. Microplastics morphological characteristics and their main drivers differed between environmental media (water and sediment) and were more diverse in waters compared to sediments. Similarity in microplastic morphologies decreased with increasing geographic distance within the same media. In terms of risks, microplastic pollution and potential ecological risk levels are high in reservoirs and current policies to mitigate microplastic pollution are insufficient. Based on the DM framework, we identified temperate/subtropical reservoirs in Asia as potential high-risk areas and offer recommendations for analytical methods to detect microplastics in waters and sediments. This framework can be extended and applied to other multi-scale and multi-attribute contaminants, providing effective theoretical guidance for reservoir ecosystems pollution control and management.


Sensitivity of parameters on the deduced microplastic abundance. (a) The relationship between the Level 2p data (solid line) and the same data but for the terminal rise velocity of 0. 009 m s− 1 (dash-dot-dash line) and 0.019 m s− 1 (dashed line). (b) The relationship between the Level-2w1 data (solid line) and 2w2 data (dash-dotted line)
Microplastic abundance at (a) Level 0 and (b) Level 1. Abundance is represented by the colors in the scales shown at the bottom of each panel
Same as Fig. 2, but for (a) Level 2p and (b) Level 2w1
Same as Fig. 2, but for (a) Level 3p and (b) Level 3w1
Same as Fig. 2, but for (a) Level 3 pm in February, (b) Level 3 pm in August, (c) Level 3wm in February, and (d) Level 3wm in August
A multilevel dataset of microplastic abundance in the world’s upper ocean and the Laurentian Great Lakes

September 2021

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942 Reads

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153 Citations

Microplastics and Nanoplastics

A total of 8218 pelagic microplastic samples from the world’s oceans were synthesized to create a dataset composed of raw, calibrated, processed, and gridded data which are made available to the public. The raw microplastic abundance data were obtained by different research projects using surface net tows or continuous seawater intake. Fibrous microplastics were removed from the calibrated dataset. Microplastic abundance which fluctuates due to vertical mixing under different oceanic conditions was standardized. An optimum interpolation method was used to create the gridded data; in total, there were 24.4 trillion pieces (8.2 × 10 ⁴ ~ 57.8 × 10 ⁴ tons) of microplastics in the world’s upper oceans.


Distribution, abundance and spatial variability of microplastic pollution on the surface of Lake Superior

August 2021

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53 Reads

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23 Citations

Journal of Great Lakes Research

In 2014, 94 paired neuston net samples (0.5 mm mesh) were collected from the surface waters of Lake Superior. These samples comprise the most comprehensive surface water survey for microplastics of any of the Great Lakes to date, and the first to employ double net trawls. Microplastic abundance estimates showed wide variability, ranging between 4000 to more than 100,000 particles/km² with most locations having abundances between 20,000 to 50,000 particles/km². The average abundance in Lake Superior was ~30,000 particles/km² which was similar to previous estimates within this Laurentian Great Lake and suggests a total count of more than 2.4 billion (1.7 to 3.3 billion, 95% confidence interval) particles across the lake’s surface. Distributions of plastic particles, characterized by size fraction and type, differed between nearshore and offshore samples, and between samples collected in the eastern versus western portion of the lake. Most of the particles found were fibers (67%), and most (62%) were contained in the smallest classified size fraction (0.50–1 mm). The most common type of polymer found was polyethylene (51%), followed by polypropylene (19%). This is consistent with global plastics production and results obtained from other studies. No statistically significant difference was detected between the paired net samples, indicating that single net sampling should produce a representative estimate of microplastic particle abundance and distribution within a body of water.


Spatial Distribution of Microplastics in Surficial Benthic Sediment of Lake Michigan and Lake Erie

December 2020

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273 Reads

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97 Citations

Environmental Science and Technology

The spatial distribution, concentration, particle size, and polymer compositions of microplastics in Lake Michigan and Lake Erie sediment were investigated. Fibers/lines were the most abundant of the five particle types characterized. Microplastic particles were observed in all samples with mean concentrations for particles greater than 0.355 mm of 65.2 p kg–1 in Lake Michigan samples (n = 20) and 431 p kg–1 in Lake Erie samples (n = 12). Additional analysis of particles with size 0.1250–0.3549 mm in Lake Erie resulted in a mean concentration of 631 p kg–1. The majority of polymers in Lake Michigan samples were poly(ethylene terephthalate) (PET), high-density polyethylene (HDPE), and semisynthetic cellulose (S.S. Cellulose), and in Lake Erie samples were S.S. Cellulose, polypropylene (PP), and poly(vinyl chloride) (PVC). Polymer density estimates indicated that 85 and 74% of observed microplastic particles have a density greater than 1.1 g cm–3 for Lake Michigan and Lake Erie, respectively. The current study provided a multidimensional dataset on the spatial distribution of microplastics in benthic sediment from Lake Michigan and Lake Erie and valuable information for assessment of the fate of microplastics in the Great Lakes.


High levels of pelagic plastic pollution within the surface waters of Lakes Erie and Ontario

April 2020

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131 Reads

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54 Citations

Journal of Great Lakes Research

During 2012 to 2014 five expeditions collected surface water samples for plastic pollution analysis representing the first data within Lake Ontario and the first multi-year dataset for Lake Erie. Lake Ontario had the highest abundances of any Great Lake to date with an average of over 230,000 particles/km². Though having a considerable smaller average of ~45,000 particles/km², Lake Erie remains second only to Lake Ontario based on studies to date and averaged across all samples and years. The high levels of pelagic plastic pollution is likely owing to their position as the last two lakes in the Laurentian Great Lakes ecosystem, as well as the prominence of population centers along their shorelines. As with previous studies, most particles were found within the smallest size classification (0.355–0.999 mm; 73%), with fragments (63%) and pellets (26%) forming the dominant morphologies. The minor contribution of fibers/lines (4%) is consistent with previous Great Lakes studies, though not with studies within other environmental compartments (e.g., sediment, fish, atmospheric). This could be due to the negative buoyancy of polymeric fibrous materials, a hypothesis consistent with the dominance of the less dense polymers polyethylene (46%) and polypropylene (43%) (based on FTIR analysis). For the first time, the multiyear Lake Erie samples were compared to modeled plastic distributions and found to fit reasonably well. Using the sample data to calibrate the model we estimate that there are 475 million plastic particles, with a total mass of 6.45 metric tons, floating on the surface of Lake Erie alone.


Figure 1. Site location map. Microplastic sampling locations, including wading points (black dots) and boat transects (black lines) are shown along with streams (blue lines) and watershed boundaries (darker gray lines) for the Milwaukee, Menomonee, and Kinnickinnic Rivers. 32,33 The harbor rock wall separating Lake Michigan from the Outer Harbor is also shown (light gray lines). [MCB, Milwaukee River near Cedarburg; MMF, Menomonee River at Menomonee Falls; MEP, Milwaukee River at Milwaukee; MWW, Menomonee River at Ridge Blvd.; KKJ, Kinnickinnic River at Jackson Park; KKE, Kinnickinnic River at S. 11th St.; KKF, Kinnickinnic River at S. 1st St.; INH, Milwaukee Inner Harbor; OUH, Milwaukee Outer Harbor; LAK, Lake Michigan].
Figure 3. Mean water concentrations by microplastic particle type and mean depth for the six sampling locations where samples were collected at different water subsurface depths. [MEP = Milwaukee River at Milwaukee; MWW = Menomonee River at Ridge Blvd.; KKF = Kinnickinnic River at S. 1st St.; INH = Milwaukee Inner Harbor; OUH = Milwaukee Outer Harbor; LAK = Lake Michigan; p m −3 = particles per cubic meter].
Figure 4. Sediment concentrations by microplastic particle type. Sampling locations are grouped by a river system, estuary and Lake Michigan with river sampling locations arranged from upstream to downstream locations, left to right for each river, the three estuary locations (KKF, INH, and OUH) and Lake Michigan (LAK). [MCB = Milwaukee River near Cedarburg; MEP = Milwaukee River at Milwaukee; MMF = Menomonee River at Menomonee Falls; MWW = Menomonee River at Ridge Blvd.; KKJ = Kinnickinnic River at Jackson Park; KKF = Kinnickinnic River at S. 1st St.; INH = Milwaukee Inner Harbor; OUH = Milwaukee Outer Harbor; LAK = Lake Michigan; p kg −1 sediment, dry wt = particles per kilogram of sediment, dry weight].
Figure 5. Relative percent difference between the water surface and depth-weighted concentration in water samples by (A) sampling location, (B) microplastic type, and (C) particle size fraction. [MEP = Milwaukee River at Milwaukee; MWW = Menomonee River at Ridge Blvd.; KKF = Kinnickinnic River at S. 1st St.; INH = Milwaukee Inner Harbor; OUH = Milwaukee Outer Harbor; LAK = Lake Michigan].
Figure 6. (A) Sum of the estimated fraction of total particles and polymers by density. (B) The estimated fraction of total particles and polymers by compartment sampled, arranged by increasing density (ρ) 58,62−64 from top left to right within each color group. Roughly 97% of the foam in the sediment was black foam identified as SBR. The density of tire wear particles was used for SBR. Only polymers that represented greater than 1% of particles collected are represented in individual polymer charts. [PP = polypropylene; E.P.D.TP = ethylene/propylene/diene terpolymer; LDPE = low-density polyethylene; HDPE = high-density polyethylene; PS = polystyrene; Nylon = nylon; SBR = styrene butadiene rubber; PAN = polyacrylonitrile; PVA = poly(vinyl acetate); POM = polyoxymethylene; PET = poly(ethylene terephthalate); Unknown = the polymer was not identified; ρ = density].
Vertical Distribution of Microplastics in the Water Column and Surficial Sediment from the Milwaukee River Basin to Lake Michigan

October 2019

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877 Reads

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355 Citations

Environmental Science and Technology

Microplastic contamination was studied along a freshwater continuum from inland streams to the Milwaukee River estuary to Lake Michigan and vertically from the water surface, water subsurface, and sediment. Microplastics were detected in all 96 water samples and 9 sediment samples collected. Results indicated a gradient of polymer presence with depth: low-density particles decreased from the water surface to the subsurface to sediment, and high-density particles had the opposite result. Polymer identification results indicated that water surface and subsurface samples were dominated by low-density polypropylene particles, and sediment samples were dominated by more dense polyethylene terephthalate particles. Of the five particle-type categories (fragments, films, foams, pellets/beads, and fibers/lines), fibers/lines were the most common particle-type and were present in every water and sediment sample collected. Fibers represented 45% of all particles in water samples and were distributed vertically throughout the water column regardless of density. Sediment samples were dominated by black foams (66%, identified as styrene–butadiene rubber) and to a lesser extent fibers/lines (29%) with approximately 89% of all of the sediment particles coming from polymers with densities greater than 1.1 g cm–3. Results demonstrated that polymer density influenced partitioning between the water surface and subsurface and the underlying surficial sediment and the common practice of sampling only the water surface can result in substantial bias, especially in estuarine, harbor, and lake locations where water surface concentrations tend to overestimate mean water column concentrations.



GESAMP 2019 Guidelines for the monitoring & assessment of plastic litter in the ocean Reports & Studies 99 (editors Kershaw, P.J., Turra, A. and Galgani, F.)

February 2019

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3,877 Reads

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22 Citations

This report was the product of a GESAMP Working Group, consisting of 15 independent experts based in North America, South America, Asia, Africa, Europe and Australasia. The report was edited by Kershaw, Turra and Galgani. It with provides recommendations to encourage a more harmonised approach to the monitoring and assessment of plastic litter, including microplastics, in the ocean. It is intended to support the development and implementation of marine litter monitoring programmes by national and regional bodies, including in relation to the Sustainable Development Goals, specifically indicators and sub-indicators of SDG 14.1.1 The report covers, definitions, survey design, sampling methods for the four main environmental compartments (shoreline, seawater, seafloor and biota), sample processing and sample characterisation (physical, chemical & biological)


Microplastic density averaged across individual bottles and lots by brand. Blue bars are densities for “NR + FTIR confirmed particles” (>100 um); Orange bars are for “NR tagged particles” (6.5–100 um). Error bars are one standard deviation. Percentages are for the contribution to the total for “NR tagged particles” (6.5–100 um); Contribution of larger particles can be inferred.
Polymeric content of microplastic particles >100 um found within bottled water. PP, polypropylene; PS, polystyrene; PE, polyethylene; PEST, polyester + polyethylene terephthalate; Others includes Azlon, polyacrylates and copolymers.
Morphologies of microplastics >100 um found within bottled water.
Comparison of counts using the “Galaxy Count” software relative to the known number of microplastic particles within four test solutions.
Comparison of microplastic counts by the “Galaxy Count” software for particles <100 um within all 259 bottles tested by two researchers working independently of one another.
Synthetic Polymer Contamination in Bottled Water

September 2018

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5,320 Reads

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868 Citations

Eleven globally sourced brands of bottled water, purchased in 19 locations in nine different countries, were tested for microplastic contamination using Nile Red tagging. Of the 259 total bottles processed, 93% showed some sign of microplastic contamination. After accounting for possible background (lab) contamination, an average of 10.4 microplastic particles >100 um in size per liter of bottled water processed were found. Fragments were the most common morphology (66%) followed by fibers. Half of these particles were confirmed to be polymeric in nature using FTIR spectroscopy with polypropylene being the most common polymer type (54%), which matches a common plastic used for the manufacture of bottle caps. A small fraction of particles (4%) showed the presence of industrial lubricants. While spectroscopic analysis of particles smaller than 100 um was not possible, the adsorption of the Nile Red dye indicates that these particles are most probably plastic. Including these smaller particles (6.5–100 um), an average of 325 microplastic particles per liter of bottled water was found. Microplastic contamination range of 0 to over 10,000 microplastic particles per liter with 95% of particles being between 6.5 and 100 um in size. Data suggests the contamination is at least partially coming from the packaging and/or the bottling process itself. Given the prevalence of the consumption of bottled water across the globe, the results of this study support the need for further studies on the impacts of micro- and nano- plastics on human health.


Citations (23)


... Additionally, community efforts raise awareness and foster a sense of environmental stewardship among participants, reinforcing the importance of individual actions in reducing microplastic pollution. Through collective, hands-on participation, communities play a direct role in mitigating microplastic contamination and supporting ecosystem health (Jenkins et al., 2022). Table 4 presents a comparation of the findings, limitations, and contributions between this work and previous studies. ...

Reference:

Combating microplastic pollution in Malaysia's marine ecosystems using technological solutions, policy instruments, and public participation: A review
Current State of Microplastic Pollution Research Data: Trends in Availability and Sources of Open Data

... In contrast, there was a significant increase in the proportion of fragment microplastics in the river water at the DG reach, which may be related to the high hydraulic disturbance due to the river's high mobility 10 . Meanwhile, the high proportion of fiber microplastics in the river water at HY and HZ may also be related to the large discharge of washing wastewater, as HY and HZ are well-known tourist resorts 11,20 . Additionally, as crucial agricultural production regions, HY and HZ use a large amount of plastic agricultural films in the agricultural production process, which leads to large substantial film microplastic emissions. ...

Global meta-analysis of microplastic contamination in reservoirs with a novel framework
  • Citing Article
  • November 2021

Water Research

... Plastic debris/trashes are categorized by their size; mega-debris, macro-debris, mesodebris, and micro-debris (microplastics) are the three main categories (Ryan et al., 2009;Thompson et al., 2009;Weiss et al., 2006). The term "nanoplastics" refers to plastic waste that is smaller than 0.1 µm or SWRCB, 2020; Isobe et al., 2021;Prapanchan et al., 2023). Examples of various plastic debris, including micro-and nanoplastic particles, and their sizes responsible for environmental and biological toxicity are found almost everywhere (Fig. 1). ...

A multilevel dataset of microplastic abundance in the world’s upper ocean and the Laurentian Great Lakes

Microplastics and Nanoplastics

... Previous studies of larger (>500 μm) microplastic particles in Lake Superior collected by Manta net found fibers as the predominant morphology (67%) with fragments present at 23%. 26 Microplastic particles in the lake, like those in the harbor, were predominantly translucent or white (72%, SI Figure S3). The higher proportion of white or translucent particles in the lake relative to the harbor follows similar trends to those seen in studies of micro and macroplastic particles (0.2 mm to 15 cm) in marine surface waters, where larger proportions of white particles were seen in both smaller particles (<5 mm) and offshore particles. ...

Distribution, abundance and spatial variability of microplastic pollution on the surface of Lake Superior
  • Citing Article
  • August 2021

Journal of Great Lakes Research

... Synthetic microfibers that are denser than water, such as polyethylene terephthalate (polyester), are inclined to sink and deposit in the benthos (Adoni et al., 2022). These particulate pollutants may also accumulate in a variety of sinks for surface waters, namely sediments and benthic algae (Barnes et al., 2024;Bergmann et al., 2023;Lenaker et al., 2021;Peller et al., 2021). ...

Spatial Distribution of Microplastics in Surficial Benthic Sediment of Lake Michigan and Lake Erie

Environmental Science and Technology

... In addition to microplastics, microscopic anthropogenically modified materials such as cotton, cellulose, and glass beads (hereafter referred to as microparticles; Miller et al., 2021) are present in freshwater systems. Within the Laurentian Great Lakes, the highest concentrations of microplastics have been reported in surface waters (Eriksen et al., 2013;Mason et al., 2020), sediments (Ballent et al., 2016), beaches (Zbyszewski et al., 2014), and biota (Munno et al., 2022) near urban centers. However, their presence in abiotic and biotic matrices is less studied in the watersheds and tributaries that drain into these lakes (Baldwin et al., 2016;Corcoran et al., 2020;Dean et al., 2018;Hoellein et al., 2014), despite tributaries often having higher particle concentrations than the lakes themselves (Cable et al., 2017;McIlwraith et al., 2023). ...

High levels of pelagic plastic pollution within the surface waters of Lakes Erie and Ontario
  • Citing Article
  • April 2020

Journal of Great Lakes Research

... Microplastics, plastic particles less than 5 mm in diameter, are present in the environment as beads, films, fragments, and fibers (GESAMP, 2019). In the Great Lakes, microplastics have been identified and quantified throughout interconnecting tributaries, surface waters, sediments, and in association with aquatic vegetation (Baldwin et al., 2016;Lenaker et al., 2019;Peller et al., 2021;Peller et al., 2019). Among the most recovered groups of microplastics are synthetic microfibers (MFs), many of which originate from plastic-based textiles such as clothing, rugs, and fishing nets (Carr, 2017;Mishra et al., 2019). ...

Vertical Distribution of Microplastics in the Water Column and Surficial Sediment from the Milwaukee River Basin to Lake Michigan

Environmental Science and Technology

... Furthermore, from a global perspective, there is an urgent need for more field surveys on marine microplastics in the ASEAN region. The distribution maps proposed by Eriksen et al. (2014) and Isobe et al. (2021) demonstrate a lack of in-situ abundance data for microplastics in the seas surrounding the ASEAN region (e.g., Michida et al., 2019). Also, previous studies have struggled with data comparability because of a lack of research results produced by the harmonized techniques proposed by, for example, Michida et al. (2019) (e.g., Nakano et al., 2024. ...

Guidelines for Harmonizing Ocean Surface Microplastic Monitoring Methods Guidelines for Harmonizing Ocean Surface Microplastic Monitoring Methods

... 13,24,35 It is important that selectivity (e.g., size range of plastic debris captured) is documented and that data collection methods and reporting metrics are harmonized. 53,59,60 Counts data are generally used in plastics monitoring and would be relevant in this context too. Most clean-up technologies targeting macroplastics are unlikely to capture the very large items that account for the large differences in identifying the main sources of litter when using counts as compared to weights. ...

GESAMP 2019 Guidelines for the monitoring & assessment of plastic litter in the ocean Reports & Studies 99 (editors Kershaw, P.J., Turra, A. and Galgani, F.)

... These microspheres were selected because (1) their color allows for easy visual monitoring of spillage and homogeneity of the suspensions, and (2) the uniform spherical shape simplifies their representation in model simulations. The 20-70 μm size range also overlaps with the dominant size range of microplastic particles found in bottled water, an area of heightened public concern [46]. ...

Synthetic Polymer Contamination in Bottled Water