A recent survey by a foreign agency found that the amount of waste plastic floating in the ocean is far less than estimated, only one-tenth of the original estimate of 4 million to 12 million tons. The degradation cycle of plastics is usually 200 to 400 years, so where does the waste plastic go?

Lu Shaoguo, a professor of ecotoxicology at the College of Marine Life at Ocean University of China, recently published his research results on Marine microplastics in the frontier journal Environmental Pollution, and the relevant results show that Marine plastics are difficult to degrade in a short time.

Lu Shaoguo told the Science and Technology Daily reporter that there are about 6-12 million tons of plastic waste discharged from the land into the ocean every year, and these plastic fragments will gradually crack into microplastics with a particle size of less than 5 mm in the environment. These microplastics are chemically stable, can exist in the environment for hundreds of years to thousands of years, and by ocean currents, wind for long-distance migration, all over the ocean. These microplastics are easily ingested by Marine organisms and transported through the food web to affect the entire Marine ecosystem. And, of course, the effects are devastating.

Their findings also show that microplastics have a large specific surface area and are prone to enrich toxic and harmful substances, causing a combined toxic effect on Marine life.

However, not all researchers agree with the idea that Marine plastics are hard to degrade. University of Hawaii researcher Richard Royle has found plastic fragments in seawater that break down into gases such as carbon dioxide, methane and ethylene when exposed to sunlight. He believes that once the decomposition process is activated, plastic will continue to degrade even when it is out of light.

The National Engineering Research Center of Engineering Plastics of the Institute of Physics and Chemistry of the Chinese Academy of Sciences is one of the highest level research and industrialization bases of polymer materials in China. It was the first to carry out research on seawater degradable materials in China. Through many tests, Wang Gexia, a senior engineer at the institute, found that materials with good biodegradability in soil and compost did not degrade as well as expected in seawater.

To get to the bottom of the matter, Wang Gexia found the answer: "The composting process of polyester materials is an enzymatic hydrolysis reaction under the action of microorganisms; And the sea temperature is low, the number of specific microbial species is small, it is difficult to have the conditions for biodegradation, so most polyester materials in the sea water degradation cycle is very slow, even difficult to degrade."

"Plastic waste in the oceans will increase threefold between 2015 and 2025." That's what Boyd, chief scientist at the UK's environment Department, predicts in the Forward Looking Ocean Future Report. So where is this multiplying amount of ocean plastic going? One answer could be in the bellies of all kinds of fish.

When plastic is "eaten" into a fish's stomach, it is not digestible like normal food, but becomes toxic, profoundly affecting the development of the fish's body.

Since 2017, Ru Shaoguo's team has carried out related research from the two aspects of pollution investigation and biotoxicity of microplastics. For example, in terms of biological toxicity, they found that microplastics could not only damage the structural characteristics and oxidative stress defense system of the intestinal tract, gill, gonad and other tissues of Marine aphyosemion, but also interfere with the reproductive and offspring development of fish, confirming for the first time that microplastics have reproductive endocrine disrupting effects.

In addition, they found that high concentrations of microplastics would accumulate on the egg shells of Marine bluemion, interfering with the development of embryos and early larva; Their joint exposure experiment found that low concentrations of microplastics reduced the early developmental toxicity of phenanthophenes to sea lifish by reducing the bioconcentration of persistent organic pollutant phenanthophenes in fish.

These important findings by the Ru Shaoguoteam provide an important reference for assessing the ecological risks of Marine microplastics. However, Wang Gexia and his team managed to get out of the difficult situation of degradation. Starting from molecular design and two-phase synthesis, they introduced non-enzymatically hydrolyzed groups into the biodegradable polyester system through two ways of polymer synthesis modification and blending modification, and realized the overall controlled degradation of the material in seawater.

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