The issue of microplastics has introduced an entirely new phase of marine plastic pollution for the 21st century. Plastics have spread throughout the marine ecosystem including the surface water, bottom sediments, and various marine organisms. Hazardous chemicals associated with marine plastics are also entering marine ecosystems. The major sources of marine plastics are disposable single-use plastics. Due to the persistence and potential hazard of marine microplastics, precautionary actions to reduce inputs of plastic wastes into the seas have been taken up internationally. Reduction of single-use plastics should be prioritized over incineration of plastic wastes, and even over “waste-to-energy” or recycling options. All solutions must be sustainable, circular, and co-beneficial with regard to global warming and other environmental problems based on the global material cycles viewpoint.

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Mismanaged plastic wastes generated in East and Southeast Asian countries account for 55% of the world’s total amount of “macroplastics”. These macroplastics released into the ocean environment are being carried by ocean currents and wind (i.e. lee-way drift) on the surface of the sea. In the ocean, they are then gradually fragmentized into “microplastics” due to their being exposed to ultraviolet radiation and mechanical erosion on beaches. Pelagic microplastics are carried by ocean currents and the Stokes drift in conjunction with removal processes such as settling due to biofouling. The fate of microplastics in the circulation of ocean plastics, including both physical transport and removal processes, remains unknown.

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Marine litter has become a global issue and there is concern that plastic waste is wreaking havoc on marine ecosystems. In Japan, the government agencies connected to the Ministry of the Environment have been dealing with the marine litter problem through a legislation known as the Act on Promoting the Treatment of Marine Debris Affecting the Conservation of Good Coastal Landscapes and Environments to Protect Natural Beauty and Variety, which was enforced in 2009. The Ministry of the Environment has promoted the following activities: (1)Collecting and preventing marine litter on Japanese coasts; (2)Monitoring the amount, allocation, and toxic substances of marine litter (including microplastics) on Japanese coasts and in the seas around Japan; and (3)Cooperating internationally to tackle marine litter with Asian countries as well as global international frameworks. In June 2018, the Act was partly amended and efforts to combat the problem of microplastics have now been included in the Act. We will continue to promote all endeavors to reduce marine litter in our own country and international cooperation to solve marine litter issues based on this amended Act.

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This paper summarizes the major points related to the EU plastic strategy as well as the relevant policy trends and initiatives for establishing a circular economy. While plastic production and consumption is increasing, the recycling rate for waste plastics remains low and there is ever growing concern for ocean environments due to the abundant proliferation of plastic litter. The EU plastic strategy has set an ambitious vision/target to close the loop and reduce the environmental impact of plastic wastes, while simultaneously aiming to achieve economic growth and lower greenhouse gases. The revised waste directive, which specifically prioritizes mandatory recycling targets on plastic packaging, has become the pivotal force behind the promotion of the new strategy.
　Within the strategy, various measures have been established to achieve ambitious targets such as a voluntary commitment campaign, restriction on oxo-biodegradable plastic and intentional use of microplastic, financing, and EPR (Extended Producer Responsibility) application. In response to such new dynamism surrounding the plastic strategy, several multinational companies and relevant industrial associations have pledged their voluntary commitment to the reduction of plastic waste.

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In this paper, we overview policies for the reduction of single-use plastics throughout the world, especially Europe. Almost all of the EU member states have already introduced ban or levy policies on plastic carrier bags in order to meet the EU target of less than 40 bags per person per year by the end of 2025. The present issues are the scope and the policy instruments for a ban on microbeads and single-use plastics. There are more than sixty countries in the world that have introduced these ban or levy policies on plastic carrier bags. Recently Sri Lanka, Taiwan, and India began more comprehensive ban policies on single-use plastics. The Japanese government has shown its intention to address these issues by amending the Law for the Promotion of Marine Litter Disposal but has not yet built its action plan. The government is expected to soon take the big step toward eliminating single-use plastics.

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This article presents some suggestions for reducing ocean garbage related to riverside littering based on academic reviews of studies on littering and followed by lab/field experiments conducted by the authors at riverside areas. For the laboratory experiment, participants looked at pictures and had to choose which scene showed a situation where littering was most likely to take place. Subsequent field experiments measured daily amounts of garbage in the Natori River (Miyagi Prefecture) after manipulating certain conditions. Both experiments examined the effects of a security camera (presence/absence), previous littering trends (presence/absence), environmental features (tussock/plain ground/flowerbed), and signboards (no sign/sign with eyes/security camera images). Results revealed that the sense of being under surveillance, descriptive norms, and emotional breaks do effectively reduce littering. Although these findings can be implemented to reduce littering at seaside areas, waste disposal management technicalities become more complicated when considering the proliferation of such garbage into the ocean.

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To show that the handling of debris from on the land and in and around rivers becomes a source of marine plastics debris and microplastics, this paper follows the transport of riverine debris, the composition of riverine debris, and microplastics pollution based on several field surveys. The results of surveys indicate that most riverine debris is being transported during flooding conditions and 6% of all this debris is artificial debris, i.e. plastics. This clearly demonstrates that debris from land and rivers is ultimately becoming a source for marine plastics. Microplastics pollution escalated along with this increase in the urban ratio of the river basin. Capture technology for flowing riverine debris to reduce the inflow of floating debris into oceans is discussed in the paper.

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