Microplastic concentrations in the Chukchi and Beaufort Sea sediments during the cruise MR22-06C of the R/V Mirai of JAMSTEC

The distribution of microplastic in the open ocean of the Arctic Ocean is largely undocumented. Substantial numbers of studies on microplastics have been reported in the Pacific and Atlantic Oceans, yet very few data are available in the polar oceans. In the present study, we conducted microplastic surveys along the cruise track to fill gaps in the Arctic Ocean.
A multiple corer system (Asyura) equipped with three aluminum tubes was used to collect microplastics in the sea floor sediment. The aluminum tube is 60 cm length and 7.4 cm inner diameter. At the beginning of multiple corer system going down, the speed of wire out was set to be 0.5 m s-1. Wire out was stopped at a depth about 10 m above the seafloor and the corer system was left stand for 1 minute to reduce any pendulum motion of the system. After the multiple corer system was stabilized, the wire was stored out at a speed of 0.5 m s-1 with carefully watching a tension meter. After confirmation of the multiple corer system touching the bottom, the wire continued out till bowing. The rewinding of the wire was started at a dead slow speed (0.3 m s-1), and then winch wire was wound up at 0.5 m s-1. Two of the three cores were used for microplastic analysis and one for paleoenvironmental analysis. In the laboratory, 100% cotton lab coats without plastic fibers were worn. Surface sediment (top ca. 5 cm of sediment core) were taken from the sediment core samples at 1 cm intervals and stored in a freezer until analysis.