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IOC Sub-Commission for the Western Pacific (WESTPAC)

Advancing knowledge and cooperation for a healthy ocean and prosperous society

UN22: Stem the Tide of Asia’s Riverine Plastic Emission Into the Ocean

Why is it important?

Plastics are fossil fuel-derived products that was created about a century ago, and the utility of plastics revolutionized our life consequently. Their plasticity makes it possible to not only serves as convenient containers that widely used in our daily life and household, but it also allowed the invention of many life-saving devices (medical devices for example) and the implementation of new technologies in almost all industries that contributed to the technical evolution vitally.


As two sides of a coin, the great advantages of plastic as its durability, longevity and chemical resistance resulted to its dark side: it is hard to degrade and consequently pose threat to our environment and all lives on the earth.

It was estimated that the production of plastics is exceeding 300 million tons per year worldwide since 2014 and increasing continuously, currently about 8 to 10 million tons of plastic end up in the ocean and consequently make plastics the largest segment of marine litter.

Roughly 80% of the marine plastics are originally generated from littering and improper management of disposable plastic items (food wrappings, plastic bags, razors, bottles, etc.), which end up in the waterways and eventually being drifted into the ocean. More specifically, about 80% of ocean macro-plastic debris (>5 mm) have terrestrial origins, while ~98% of micro-plastics (MP, < 5 mm) are from land-based sources. The rivers are therefore widely regarded as a major transport pathway for all sizes of plastic debris into the ocean, while plastics also reach the ocean through other processes for instance direct littering near beaches, followed by tidal or wind transport.

Marine plastic pollution is generating impacts on marine biota and ecosystems at many different levels, such as microplastic ingestion by marine invertebrates, planktivorous fish and seabirds inhabiting the oceanic waters and islands; entanglement of seabirds, sea turtles, marine mammals in large plastic litter (nets, ropes, etc.); habitat damaging to marine wildlife at nearshore wetlands, mangroves, coral reefs and even in deep and remote places. Marine plastic pollution also leads to economic loss (tourism, fisheries, aquaculture, etc.), vessel damage and navigation hazard, and potentially threatens human health through bioaccumulation and biomagnification of toxic contaminants and associated chemical additives.

Plastic and microplastic pollution have been at top agenda of a number of national and international agreements and frameworks. Particularly, the United Nations General Assembly proclaimed in 2017 a Decade of Ocean Science for Sustainable Development (2021-2030) to gather ocean stakeholders worldwide and catalyze ocean science solutions to sustainable development of the ocean, and the United Nations Environment Assembly (UNEA-5.2) in 2022 unanimously approved a historic resolution to develop an internationally binding instrument on plastic pollution, including in the marine environment.

Rivers are recognized as plastic reservoirs and major pathways for land-based plastic transported to the ocean. Based on previous model results, the rivers in the Asia-Pacific accounted for more than half of the global riverine plastic waste. However, arguments have been mounting about the modelling results due to the lack of in-situ observations, and community-based actions are needed to reduce the plastic export to the rivers, and eventually into the ocean. This transboundary environmental challenge needs to be addressed urgently through concrete actions at all levels involving international coordination and cooperation, scientific research and technology innovations, local actions, citizen and corporate commitment.

What we do?

The IOC Sub-Commission for the Western Pacific (WESTPAC) with countries and their institutions in the region developed and registered a UN Ocean Decade Action (“UN22. Stem the tide of Asia’s riverine plastic emission into the ocean”) in 2022, with the purpose to serve the needs of Member States in the region to better understand the status of river inputs of plastic waste into the ocean, and to generate timely data, information and knowledge needed to formulate and implement technological, behavioral, and policy solutions. This Decade Action was built on the past achievements that the Sub-Commission has made since 2017 in marine microplastic research and monitoring, capitalizing on the well-established regional research and monitoring network of institutions, enhanced national and regional capacity for plastic research and monitoring, and the ever-increasing commitment of Member State to combating marine plastic pollution.

The objectives of the Action are to:

  • Develop a better understanding of the sources, pathways, fluxes, leakage and accumulation hotspots of river plastic and microplastics via co-designed field samplings, site visits, analysis, and modeling.

  • Catalyze management, infrastructure, technological and behavioral solutions to reduce riverine plastic waste, via the conduct of joint research, capturing and sharing of lessons learned and best practices, technology innovation, and engagement of local authorities, NGOs, business and private sectors, and other stakeholders if relevant.

  • Develop research capacity of young scientists and students in developing countries for marine plastic and microplastic research and morning.

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