A novel in situ and graded sampling system for seawater microplastics

Resumen

The net trawling method requires complicated operations, during which samples are susceptible to contamination in an open environment. In this context, a novel in situ and graded sampling system for seawater microplastics was developed. This system integrates the collection, separation, and enrichment procedures and features alternate air-water elution and three-layer graded collection (membrane mesh sizes of 300, 100, and 50 μm). Its advantages are ease of operation, reduced operation time, seawater recycling, and forming a closed space to avoid sample contamination. Moreover, it is capable of measuring the filtered seawater volume accurately. An in-shore experiment was carried out to collect microplastic samples with the new system. These samples were analyzed and identified by micro-Raman spectroscopy. Microplastics with different types (PE, PET, PA, PEVA, PS, and PVS); colors (translucent, white, blue, and yellowish), and shapes (foam, fragment, fiber, and granule) were found on the 100 and 50 μm filter membranes but not on the 300 μm filter membrane. The results indicate that the new sampling system effectively collects microplastics usually omitted by trawling nets and can be used as a supplement to trawling nets.