Yee H. Lau

The global proliferation of plastics and their degradation into microplastics (<5 mm) have created a pervasive environmental crisis with severe ecological and human health consequences. Despite the exponential growth in microplastic research over the past decade, standardized protocols are still lacking. The absence of consistent sampling, analysis, and reporting methods limits data comparability, interoperability, and harmonization across studies. This study conducted a systematic bibliographic review of 355 peer-reviewed articles published between 2010 and 2022 that investigated microplastics in freshwater as well as marine water and sediment environments. The goal was to evaluate methodological consistency, sampling instruments, measurement units, reported characteristics, and data-sharing practices to identify pathways toward harmonized and FAIR (Findable, Accessible, Interoperable, and Reusable) microplastic data. Results show that 80.6% of studies focused on marine environments, 18% on freshwater, and 1.4% on both. This highlights persistent data gaps in freshwater systems, which function as key transport pathways for plastics to the ocean. Most studies targeted water (59%) rather than sediment (41%) and were mostly based on single-time sampling, limiting long-term analyses. Surface layers (<1 m) were predominantly sampled, while deeper layers remain understudied. Nets, particularly Manta, neuston, and plankton nets were the dominant tools for water sampling, whereas grabs, corers, and metallic receptacles were used for sediments. However, variations in mesh size and sampling depth introduce substantial biases in particle size recovery and reduce comparability across studies. The most common units were counts/volume for water and counts/g dry weight for sediments, but more than ten unit expressions were identified, complicating conversions. Only 35% of studies reported all four key microplastic characteristics (color, polymer type, shape, and size), and less than 20% made datasets publicly available. To advance harmonization, we recommend the adoption of consistent measurement units, mandatory reporting of key metadata, and wider implementation of open data practices aligned with the FAIR principles. These insights provide a foundation for developing robust monitoring strategies and evidence-based management frameworks. This is especially important for freshwater systems, where data remain scarce, and policy intervention is urgently needed.

CONCORDE is the CONsortium for oil spill exposure pathways in COastal River-Dominated Ecosystems (CONCORDE), and is an interdisciplinary research program funded by the Gulf of Mexico Research Initiative (GoMRI) to conduct scientific studies of the impacts of oil, dispersed oil and dispersant on the Gulf’s ecosystem (Greer et al. 2018). A CONCORDE goal is to implement a synthesis model containing circulation and biogeochemistry components of the Northern Gulf of Mexico shelf system which can ultimately aid in prediction of oil spill transport and impacts. The CONCORDE Meteorological Analysis (CMA) is an hourly gridded NetCDF dataset which provides atmospheric forcing for the synthesis model. CMA includes a variety of parameters from multiple sources. The Real-Time Mesoscale Analysis (RTMA; De Pondeca et al. 2011) provides the surface momentum and the thermodynamic atmospheric data. The radiation parameters and total cloud cover percentage are from the North American Mesoscale (NAM) Forecast System fields. The hourly precipitation is extracted from the Next Generation Weather Radar (NEXRAD) Level-III. Gridded sea surface temperature fields (SST) are computed daily using a 10-day running mean of the Advanced Very High-Resolution Radiometer (AVHRR) SST product. The Coupled Ocean-Atmosphere Response Experiment flux (COARE) algorithm calculates sensible heat flux and surface momentum stresses (Fairall et al. 2003). CMA’s spatial domain’s lowest west grid point is at 90.13°W, 29°N, and the highest east grid point is at 87.05°W, 30.94°N. The grid spacing is 0.01 degree, and the grid dimension is 309 by 195.