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2016年8月27日 (土)

海洋ごみ汚染 国際連携で拡散を防止したい

The Yomiuri Shimbun
International cooperation needed to prevent spread of marine garbage
海洋ごみ汚染 国際連携で拡散を防止したい

We hope the circle of international cooperation will widen to reduce the volume of plastic trash that is threatening the marine environment.

In fiscal 2013, about 45,000 tons of trash that had drifted ashore was retrieved along Japan’s coastline. The Environment Ministry estimates the total volume of trash washed ashore, including rubbish that was not collected, was from 310,000 tons to 580,000 tons.

Beach clean-ups conducted before and after the summer swimming season are becoming more expensive each year. In fiscal 2013, cleaning beaches around the nation cost ¥4.3 billion.

The majority of this trash is plastic, such as PET bottles and detergent containers. Some was thrown away inland but swept to the sea by rivers, while much of the trash found along the Sea of Japan coast of Kyushu and Honshu drifted ashore from overseas from countries such as China and South Korea.

A wide spectrum of steps, such as reducing the use of plastic products, recycling and campaigns to discourage people from littering, will be indispensable for curbing the overall volume of marine trash.

As global plastic production continues to increase, some estimates suggest at least 8 million tons of plastic ends up in the ocean each year. Some calculations say China and countries in Southeast Asia are among the main sources of this garbage.

At the meeting of environment ministers from the Group of Seven advanced nations held in Toyama city in May, the ministers confirmed the G-7 would lead and promote international cooperation to combat marine litter.

Japan is already engaged in efforts to address this issue with South Korea and China, and with Russia. These include sharing information on policies related to plastic litter, training on fact-finding surveys regarding marine pollution, and jointly conducting coastline clean-ups. These countermeasures will need to be expanded further with the countries concerned.

Microplastics a bugbear

Marine trash not only spoils the natural scenery of the coastline; it also damages fishing nets and becomes mixed in with marine products, lowering their commercial value. Fish and birds that accidentally swallow this trash often die.

In recent years, the increase in microplastics — plastic particles 5 millimeters in size or smaller — has become a serious problem. They are created when PET bottles and other plastic are broken into small fragments due to ultraviolet rays from sunlight or abrasive wave action. Microplastics have spread across oceans around the world, and are said to be almost impossible to remove from the environment.

The impact of microplastics even reaches smaller living creatures. Last year, a survey that Tokyo University of Agriculture and Technology conducted in Tokyo Bay found microplastics were present in almost 80 percent of 64 Japanese anchovy. Microplastics were even detected in shellfish living on the seabed.

We should also be wary of microplastics’ tendency to adsorb toxic substances such as polychlorinated biphenyl (PCB). This can accumulate in the food chain, and there are also concerns it could affect humans and the breeding of marine life.

Japan, the United States and Europe are at the forefront of research into microplastics. However, there are still only a few researchers, and methods for measuring microplastics and assessing their impact have not been standardized. Japan should use its experience and take the lead in creating a base for measures to combat microplastics.

(From The Yomiuri Shimbun, Aug. 26, 2016)


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