Every year, a huge quantity of plastic marine debris is swept ashore in Japanese coastal areas. When polystyrene decompose the styrene oligomers are produced. Since some of the styrene oligomers are toxic, it is important to understand the pollution situation of the coastal areas, and to determine how to reduce the contaminations. The authors performed field investigations in Japan, South Korea and Philippines. The results show a realistic apprehension that the pollution of the decomposed chemicals from plastics is spreading in many areas in Asia. Therefore, the pollution investigations in Taiwan Island were executed. In this paper, the method of field investigation and laboratory analysis are described first. And the field investigations and the analysis results of the Taiwan are discussed. Finally, the data of Taiwan are examined as compared with Okinawa, Tokyo Bay, Manila Bay and other data which were investigated in 2008 – 2009.


Every year, about 150,000 tons of marine debris is washed up in Japanese coastal areas. More than half of the garbage is plastic (Investigation Report of Northwest Pacific Region Environmental Cooperation Center, 2004). Much of this debris originates from garbage thrown away in inland Japan, and carried away in coastal areas by rivers. Also, a great quantity of garbage comes from the East China Sea and its surrounding countries. The polystyrene is used in many daily-used items, such as tableware, exterior of electric appliances, food packaging, and others. It has been proven that polystyrene does not decompose in ordinary temperature. However, it was shown by Saido et al. (2003, 2005 and 2009) that the polystyrene has the possibility to decompose under the average temperature conditions of beaches in subtropical area. Styrene oligomers of styrene monomer (SM), styrene dimer (SD) and styrene trimer (ST) are produced when the polystyrene decomposed.

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