A Study on Abundance and Characteristics of Drifting Plastics off the West Coast of Kyushu, Japan: Visual and Tow-net survey

Abstract

Survey on abundance and characteristics of drifting plastic debris that has renewed as marine environmental pollution was conducted off the west coast of Kyushu, Japan. Large-sized plastics such as plastic bottles and styrene that were able to be observed visually from the bridge of the ship were counted during daytime. In addition, small-sized microplastics such as microbeads and fiber were also investigated via towing surface plankton net (Newston net). Density (number of pieces per sea surface area) and compositions of plastic types in large and small-sized plastics between coastal and offshore regions were compared. Densities of large-sized plastics were 2.8 pcs/km² in offshore region and 7.1 pcs/km² in coastal region. However, densities of small-sized plastics in offshore and coastal regions were 360000 pcs/km² and 1100000 pcs/km², respectively. Density of microplastics off the West Coast of Kyushu, Japan was quite high, when compared to those in other marine regions. Countermeasure against emission of plastics into the East China Sea is needed at the earliest opportunity.