The presence of small plastic particles in the environment, reported for the first time in the 1970's, has only recently been recognized as a global issue. Although environmental awareness continues to grow, so does its consumption and associated risks. The number of studies reporting the presence of microplastics, has grown exponentially as did the concern over plastic degradation into smaller particles like nanoplastics, a potentially more pernicious form of plastic pollution.
Microplastic (MP) studies in freshwater environments are gaining attention due to the huge quantities of plastic particles reported from lakes and rivers and the potential for negative impacts in these environments. Different units have been used to report MP densities, which makes it difficult to compare data and can result in reports of extremely high concentrations that do not reflect the original sample size. We recommended that the density of MPs from bulk samples be reported as number L −1 , while density from net samples should be reported as number m −3 .
Nanoplastic is an emerging topic of relevance in environmental science. The analytical methods for microplastic have a particle size limit of a few micrometers so that new methods have to be developed to cover the nanometer range. This contribution reviews the progress in environmental nanoplastic analysis and critically evaluates which techniques from nanomaterial analysis may potentially be adapted to close the methodological gap. A roadmap is brought forward for the whole analytical process from sample treatment to particle characterization.
This review provides insight into the abundance, origin, distribution and composition of MPs in the sea surface and water column of the Mediterranean Sea. Literature data on MP particles on the sea surface showed an evident heterogeneous distribution and composition, with marked geographical differences between Mediterranean sub-basins. A standardized protocol for water sampling, extraction and detection of plastic debris is strongly recommended.
