Scientists from HR Wallingford, in Oxfordshire, and Queen Mary University created a model to simulate the breakdown of plastic and how long it takes to end up in the deep sea. They found that existing pollution would still float on the surface for more than 100 years, even if no more floating plastic was dumped in the ocean. Those behind the study said the research offered "critical insights" into "the challenges of removing plastic from marine environments".Prof Andrew Manning, technical directr at HR Wallingford, said: "This study helps explain why so much of the plastic we expect to find at the ocean surface is missing." He explained that as large plastics fragment over decades, they "become small enough to attach" to marine snow - which are tiny organic particles that sink to the ocean floor. But, even after a hundred years, he said fragments could still be found at surface level "floating and breaking down". The study found that the breakdown of plastic over the time was "the limiting factor" in removing it from the ocean surface. It found that after a century, about 10% of the original plastic could remain afloat, where it releases harmful microplastics into the water."To tackle the problem properly, we need long-term thinking that goes beyond just cleaning the surface," Prof Manning said.
The study is the third and final one of its kind by Queen Mary University of London and HR Wallingford exploring the journey of plastic in the ocean. The study found that the breakdown of plastic over the time was "the limiting factor" in removing it from the ocean surface. It found that after a century, about 10% of the original plastic could remain afloat, where it releases harmful microplastics into the water. To tackle the problem properly, we need long-term thinking that goes beyond just cleaning the surface," Prof Manning said. https://www.bbc.com/news/
And in Rivers too! Global production of plastic has increased exponentially over the past decades. Annual world production has increased from 2 million tonnes (Mt) in 1950 to 234 Mt in 2000 and 460 Mt in 2019. In a business-as usual scenario, the OECD projects global plastic production to triple by 2060. Large shares of the plastic produced soon turn out as waste, especially short-lived products such as packaging and single-use plastics – like this 353 Mt of plastic waste were generated globally in 2019 (OECD 2022). While the United States show by far the largest per capita plastic waste generation rate, major increases are expected for emerging economies in sub-Saharan Africa and Asia, where plastic waste generation is forecast to quadruple by 2060. This is alarming, as solid waste management in these countries is often inadequate and will not be able to keep up with waste generation, considering the various challenges in waste management in developing countries. Rapid urbanisation trends resulting in large informal settlements will further aggravate the situation. Plastic waste far too often ends up in the environment, polluting land, rivers, and oceans. While some types of plastic are very stable, others very slowly fragment into tiny microplastic particles and eventually further into non-visible nanoplastics. As plastics can remain in the environment for many decades and production and use of plastic continues to increase, plastic pollution will be building-up exponentially over the next decades. This is ever more worrying since the resulting risks for human and environmental health are not yet fully understood.
Microplastics are defined as plastic particles smaller than 5mm in diameter in the international policy debate, e.g. in the OECD Global Plastic Outlook. Nanoplastics are considered a subset of microplastics, usually defined as being under 100 nm in size (UNEP 2022). However, various ongoing research on microplastic and nanoplastic uses different definitions, making it difficult to compare results. • Microplastics can be categorized by their source. Primary microplastics are purposefully made to be that size (e.g. microbeads used in cosmetics and personal care products, virgin resin pellets used in plastic manufacturing processes). Secondary microplastics are the result of fragmentation of macroplastic into smaller particles, either during use or after disposal into the environment. • Microplastics make up 12% of plastic pollution flows into the environment. Most microplastics found in the environment are secondary microplastics, with major sources including road transport (tire abrasions and brake wear), synthetic fibres, and wastewater sludge. Nevertheless, primary microplastics are also an important source of plastic pollution. Moreover, microplastics in the environment, especially in rivers and oceans, result from break-down of larger plastic items. • Microplastics are found everywhere - once microplastics are released into the environment they are transported in various ways incl. through the air, rivers, and the food web, as they are ingested by animals. Like this microplastics are carried to even the most remote places, for example the arctic and high mountain glaciers. Microplastics also have been detected in human blood and lungs. The pervasiveness of microplastics across our planet raises serious concerns for human and environmental health.
The understanding of sources, pathways, and fate of microplastics in the environment is still limited. More research is needed to better understand the full extent and impacts of microplastic pollution. However, considering the fact that once leaked into the environment, microplastics are difficult to contain, this should by no means delay the implementation of preventive policies to reduce microplastic pollution.
Rivers and lakes act as plastic pollution reservoirs Around 32% of all plastic pollution ends up in aquatic environments, i.e. in rivers, lakes and oceans. Direct dumping of waste contributes a significant portion of plastic in rivers. But mismanaged waste from land can also be flushed into water bodies, e.g. by heavy rains, which feed into larger tributaries and rivers, which in turn empty into oceans. In this way, plastic from far inland can travel many miles through local streams into larger tributaries and main river down to the coastline. Rivers have for long mainly been considered a mere courier for plastic into the oceans, but more recent research found that a major part of the plastic remains within the river systems for many years, like water bottles from the 1970s at the riverbank of the Seine have shown. In 2019 alone, 5.8 Mt of plastic waste are estimated to have ended up in rivers and lakes, of which only 1.7 Mt flowed into the ocean.
Huge amounts of plastics have already accumulated in rivers and lakes and the problem is piling up: estimates are that more than 109 million tons of plastic are floating around or settling at the bottom of rivers and lakes -much more than the 30 million tons accumulated in the world’s oceans – and these numbers are expected to triple until 2060 (OECD 2022). This figure by the OECD shows current and expected plastic pollution flows in aquatic environments. Highest plastic pollution is found in rivers running through densely populated urban areas in Asia where waste management is often lacking. Researchers expect Africa to establish on the list of riverine plastic pollution hotspots in the next decades. Similar observations were made for microplastic pollution of freshwater bodies, where highest concentrations were found in China and lowest in Switzerland (Chen et al. 2022). Nevertheless, microplastics have also been found in remote Swiss mountain lakes https://www.sdc-water.ch/dam/