About Riverine MP Sampling Quality Criteria

This peer-reviewed meta-analysis evaluates the quality and consistency of microplastic sampling procedures across 36 field-based river studies, addressing a critical gap in freshwater microplastics research. Authored by J. Lofty, P. Ouro, and C.A.M.E. Wilson at Cardiff University and the University of Manchester, the work develops a ten-criterion scoring framework to assess how well river sampling studies document physical, hydraulic, and methodological information essential for understanding microplastic transport and behaviour in riverine systems. This sampling criteria is similar to others published on Plastiverse.org.

The study applies a structured quality assessment to both water column and benthic sediment sampling approaches, then synthesizes reported microplastic concentrations, polymer types, and particle morphologies across the reviewed literature. The authors found that microplastic concentrations in river water and sediment varied by five and seven orders of magnitude respectively, highlighting how sampling equipment choice and documentation gaps obscure true environmental patterns. The analysis reveals that 35 of 36 studies omitted critical information in at least one quality criterion, most commonly failing to document river physical characteristics, catchment area, and sample size rationale.

Key Features of the Quality Framework

• Ten quality criteria organized into two subsets: sampling site details (catchment area, river characteristics, location documentation) and sampling methods and strategy (sampling approach, equipment, vertical location, and replication).
• Meta-analysis showing most frequently reported polymers in river studies: polypropylene (PP), polyethene (PE), polystyrene (PS), polyethylene terephthalate (PET), and polyvinyl chloride (PVC).
• Documented particle shapes across reviewed studies: irregular-shaped particles, fibres, spheres, and films, with no standardized morphology reporting.
• Five to seven order-of-magnitude variation in reported microplastic concentrations, directly linked to sampling equipment type and methodological transparency.

Development and Validation

Published in Science of the Total Environment 863 (2023) with open access under CC BY license, this work originates from the Hydro-Environmental Research Centre at Cardiff University’s School of Engineering, with co-authorship from the University of Manchester’s School of Mechanical, Aerospace and Civil Engineering. The study employs a systematic literature review combined with quantitative meta-analysis, scoring each publication against objective quality criteria designed to align river microplastics research with hydrodynamic and transport science standards. The authors propose an idealized sampling approach to harmonize future river microplastics studies and ensure consistent reporting of variables that govern particle transport.

Access and Data Availability

The full paper is available through Lofty et al., 2023, Science of the Total Environment as an open access article published by Elsevier. The DOI link provides full access to the meta-analysis results, quality scoring framework, supplementary tables of reviewed studies, and the authors’ recommendations for standardized riverine microplastics sampling. No separate dataset or code repository is mentioned in the publication; the quality criteria and meta-analysis findings are presented within the journal article itself.

For complementary methods context, see Microplastics Sampling and Processing Guidebook — Citizen Science Methods.

Why This Resource Belongs on Plastiverse

This meta-analysis directly addresses sampling standardization in freshwater and sediment microplastics research, a foundational challenge that undermines data comparability across river studies. The ten-criterion quality framework provides actionable guidance for designing rigorous field sampling campaigns in riverine systems, while the synthesis of 36 published studies identifies common pitfalls—undocumented hydraulic conditions, inadequate replication, equipment-dependent bias—that researchers must address. Practitioners planning water column or benthic sediment sampling in rivers can use the proposed idealized sampling approach to harmonize their methods with peer research and ensure their data contributes reliably to understanding microplastic transport in freshwater environments.