Mesh selectivity of neuston nets for microplastics

Two neuston nets, mesh opening 1.00 mm and 0.333 mm, were towed in parallel. The 0.333 mm net collected more microplastics of longest length <2.00 mm than the 1.00 mm net. Mesh selection curve of the 1.00 mm mesh net for microplastics was estimated with the SELECT analysis by comparison of size distributions of microplastics collected by the two nets. Selection curve of the 0.333 mm mesh net, often used as a standard mesh size for microplastic net sampling, was also estimated on the assumption of geometrical similarity between microplastic size and mesh opening for a given retention probability. Approximately 60% amount of microplastics (0.4?1.0 mm) in net sampling with the 0.333 mm net passed through the mesh and was thus unaccounted for. The 0.333 mm net can retain at most 1.5% of microplastics <0.4 mm entering the net, and rarely retained microplastics <0.3 mm.

Automated summary

The study found that the 0.333 mm net had a better retention effect on microplastics smaller than 2.00 mm compared to the 1.00 mm net. The 0.333 mm net is able to retain larger microplastics when selecting for microplastics, but has a poor retention effect on microplastics smaller than 0.4 mm.