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Saturday, December 13, 2025

Scientists reveal how microplastics release invisible chemical clouds into waterways

New study uncovers the step-by-step molecular changes that occur as plastics leak dissolved organic matter under sunlight, with implications for ecosystems, water quality, and global carbon cycling

Biochar Editorial Office, Shenyang Agricultural University

image:
Molecular-level insights into derivation dynamics of microplastic-derived dissolved organic matter
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Credit: Shiting Liu, Xiamu Zelang, Chao Ma, Zhuoyu Li, Xinyue Wang, Hanyu Ju, Jingjie Zhang & Jiunian Guan

Researchers have discovered that microplastics floating in rivers, lakes, and oceans continuously leak a complex mixture of dissolved organic chemicals that evolve over time, especially under sunlight. The work provides the most detailed molecular-level view to date of how this microplastic-derived dissolved organic matter, or MPs DOM, forms and transforms in natural waters.

The study, published in New Contaminants, compared four major plastic types with natural dissolved organic matter from rivers. Using kinetic modeling, fluorescence spectroscopy, high-resolution mass spectrometry, and infrared analysis, the scientists showed that each type of plastic produces a distinct chemical fingerprint that changes as sunlight breaks down polymer surfaces.

“Microplastics do not just pollute aquatic environments as visible particles. They also create an invisible chemical plume that changes as they weather,” said lead author Jiunian Guan of Northeast Normal University. “Our study shows that sunlight is the primary driver of this process, and that the molecules released from plastics are very different from those produced naturally in rivers and soils.”

Sunlight accelerates the release of plastic associated carbon

The researchers exposed polyethylene, polyethylene terephthalate, polylactic acid, and polybutylene adipate co terephthalate microplastics to water under dark and ultraviolet conditions for up to 96 hours. Sunlight dramatically increased the rate at which all plastics released dissolved organic carbon. Biodegradable plastics such as PLA and PBAT released the most, reflecting their more fragile chemical structures.

Using kinetic models, the team found that the release followed zero order behavior, meaning the process was controlled by physical and chemical constraints at the plastic surface rather than by the concentration of material already in the water. Film diffusion was identified as the rate limiting step under ultraviolet light.

A chemically rich mix of additives, monomers, and oxidized fragments

Advanced spectroscopy and mass spectrometry revealed that MPs DOM contains a diverse set of molecules originating from additives, monomers, oligomers, and photo oxidized fragments. Aromatic plastics such as PET and PBAT produced particularly complex mixtures.

As plastics weathered, oxygen containing functional groups increased, indicating the formation of alcohols, carboxylates, ethers, and carbonyls. Additives such as phthalates also appeared, consistent with their weak bonding within polymer matrices.

Fluorescence analyses demonstrated that MPs DOM resembled material produced by microbial activity rather than by terrestrial sources, in sharp contrast to natural dissolved organic matter. Over time, the chemical composition shifted, with relative contributions of protein like, lignin like, and tannin like substances changing depending on polymer type and sunlight exposure.

Environmental impacts could intensify as plastic pollution grows

The evolving chemical mixtures released from microplastics could influence aquatic ecosystems in several ways. MPs DOM is generally composed of small, bioavailable molecules that may stimulate or inhibit microbial activity, alter nutrient cycling, or interact with metals and pollutants. Previous studies have shown that MPs DOM can generate reactive oxygen species, affect disinfection byproduct formation, and modify pollutant adsorption.

“Our findings highlight the importance of considering the full life cycle of microplastics in water, including the invisible dissolved chemicals they release,” said co author Shiting Liu. “As global plastic production continues to rise, these dissolved compounds may have growing environmental significance.”

Toward predictive tools for plastic pollution chemistry

Given the complexity of MPs DOM and its dynamic nature, the team suggests that machine learning approaches could help predict how this material evolves in the environment. Future models could support risk assessments related to aquatic health, contaminant behavior, and carbon cycling.

The authors note that microplastic inputs to rivers and oceans remain largely uncontrolled. As plastics continue to fragment and weather under sunlight, the release of MPs DOM is expected to intensify, making it essential to understand its chemical behavior across different stages of degradation.

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Journal reference: Liu S, Zelang X, Ma C, Li Z, Wang X, et al. 2025. Molecular-level insights into derivation dynamics of microplastic-derived dissolved organic matter. New Contaminants 1: e016

https://www.maxapress.com/article/doi/10.48130/newcontam-0025-0016

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About the Journal:

New Contaminants is an open-access journal focusing on research related to emerging pollutants and their remediation.

DOI

10.48130/newcontam-0025-0016

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Molecular-level insights into derivation dynamics of microplastic-derived dissolved organic matter

Article Publication Date

5-Dec-2025

Wednesday, December 10, 2025

Modeling microplastic accumulation under the ocean surface

A theory of how microplastic particles accumulate in ocean eddies will inform sampling strategies.

American Institute of Physics

video:
Simulation of microplastic particles in a rotating cylinder, circulating throughout the tank until they accumulate in the attractors.
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Credit: Larry J. Pratt

WASHINGTON, Dec. 9, 2025 — The ocean is saturated with microplastics. While we know the location of the great garbage patches, where plastic particles may accumulate below the ocean surface remains unknown. The vastness of the ocean means particle sampling data is sparse, but modeling how particles aggregate in 3D fluid flows can help determine where to look.

In Chaos, by AIP Publishing, researchers from the Woods Hole Oceanographic Institution established a theory for how microplastic particles may accumulate in an idealized eddy, or circular current.

Larry Pratt and Irina Rypina began by modeling how fluid moves in a rotating cylinder, a laboratory setup commonly used to investigate large-scale ocean and atmospheric flows. In it, the body of a cylinder rotates at a constant speed while its lid spins at a different rate. The resulting circulation, in which the water spins up in the middle of the cylinder and spirals down the outer edge, is seen in ocean eddies at a scale of hundreds of kilometers.

When the cylinder lid is tilted, fluid trajectories change. Particle paths are broken up into a tangled flow of chaotic orbits and new donut-shaped circulations that can give rise to attractors of slightly buoyant, small particles — stable behaviors that a system settles into.

“If you just threw a small particle into the water with some arbitrary velocity, viscous drag would rapidly bring its motion close to that of the fluid,” said Pratt. “So, to a first approximation, the microplastic particles are just following the fluid trajectories.”

The complication is that the microplastics have inertia and disrupt the fluid around them, causing them to slowly stray from the fluid’s usual path. Pratt and Rypina exploited the mathematics behind this to develop a theory for how and where particles accumulate. Applying the theory to ocean flows can help determine subsurface areas with high concentrations of microplastics.

They found that particle accumulation occurs in the center of tubelike structures that wind around circular currents. Many such structures may exist, resulting in multiple “attractors” of small particles. Each attractor resembles a twisted, closed loop that particles move along, spiraling upward and downward in the 3D flow.

Pratt and Rypina’s theory explains how, where, and why these flows occur. While their conclusions reflect experimentally and numerically observed flows, they have plans to add more realistic complications.

“The main thing we need to consider is the effects of small-scale turbulence. The theory is valid for spherical particles, but most microplastics in the ocean have very irregular shapes,” said Pratt. “Another challenge for the future is trying to track those, [and] in the immediate future, we’re hoping that the theory will inform sampling strategies and lead to a better understanding of where plastics might be accumulating.”

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The article “A theory for attractors of microplastic particles in the resonant structures of a 3D eddy” is authored by Larry J. Pratt and Irina Rypina. It will appear in Chaos on Dec. 9, 2025 (DOI: 10.1063/5.0288722). After that date, it can be accessed at https://doi.org/10.1063/5.0288722.

ABOUT THE JOURNAL

Chaos is devoted to increasing the understanding of nonlinear phenomena in all areas of science and engineering and describing their manifestations in a manner comprehensible to researchers from a broad spectrum of disciplines. See https://pubs.aip.org/aip/cha.

Left: Artwork motivated by the study, showing fluid circulation in the rotating cylinder. Right: Confined trajectories of fluid particles circulating throughout the tank when the cylinder lid is tilted, disrupting the flow.
Credit
Left credit: Larry Pratt Photo, 2013. Right credit: Pratt and Rypin

Journal

Chaos An Interdisciplinary Journal of Nonlinear Science

DOI

10.1063/5.0288722

Article Publication Date

9-Dec-2025

Friday, December 05, 2025

Microplastics Make Up Majority of US National Park Trash, Waste Audit Finds

“Even in landscapes that appeared untouched,” volunteers found “thousands of plastic pellets and fragments that pose a clear threat to the environment, wildlife, and human health,” said a 5 Gyres Institute spokesperson.

Trash is seen strewn along the road at Joshua Tree National Park in California, on October 10, 2025, on the 10th day of the federal government shutdown.
(Photo by Frederic J. Brown/AFP)

Stephen Prager
Dec 04, 2025
COMMON DREAMS

More than half the trash polluting America’s national parks and federal lands contains hazardous microplastics, according to a waste audit published Thursday.

As part of its annual “TrashBlitz” effort to document the scale of plastic pollution in national parks and federal lands across the US, volunteers with the 5 Gyres Institute collected nearly 24,000 pieces of garbage at 59 federally protected locations.

In each of the four years the group has done the audit, they’ve found that plastic has made up the vast majority of trash in the sites.

They found that, again this year, plastic made up 85% of the waste they logged, with 25% of it single-use plastics like bottle caps, food wrappers, bags, and cups.

But for the first time, they also broke down the plastics category to account for microplastics, the small fragments that can lodge permanently in the human body and cause numerous harmful health effects.

As a Stanford University report from January 2025 explained:
In the past year alone, headlines have sounded the alarm about particles in tea bags, seafood, meat, and bottled water. Scientists have estimated that adults ingest the equivalent of one credit card per week in microplastics. Studies in animals and human cells suggest microplastics exposure could be linked to cancer, heart attacks, reproductive problems, and a host of other harms.

Microplastics come in two main forms: pre-production plastic pellets, sometimes known as “nurdles,” which are melted down to make other products; and fragments of larger plastic items that break down over time.

The volunteers found that microplastic pellets and fragments made up more than half the trash they found over the course of their survey.

“Even in landscapes that appeared untouched, a closer look at trails, riverbeds, and coastlines revealed thousands of plastic pellets and fragments that pose a clear threat to the environment, wildlife, and human health,” said Nick Kemble, programs manager at the 5 Gyres Institute.

Most of the microplastics they found came in the form of pellets, which the group’s report notes often “spill in transit from boats and trains, entering waterways that carry them further into the environment or deposit them on shorelines.”

The surveyors identified the Altria Group—a leading manufacturer of cigarettes—PepsiCo, Anheuser-Busch InBev, the Coca-Cola Company, and Mars as the top corporate polluters whose names appeared on branded trash.

But the vast majority of microplastic waste discovered was unbranded. According to the Coastal & Estuarine Research Federation, petrochemical companies such as Dow, ExxonMobil, Shell, and Formosa are among the leading manufacturers of pellets found strewn across America’s bodies of water.

The 5 Gyres report notes that “at the federal level in the United States, there is no comprehensive regulatory framework that specifically holds these polluters accountable, resulting in widespread pollution that threatens ecosystems and wildlife.”

The group called on Congress to pass the Reducing Waste in National Parks Act, introduced in 2023 by Sen. Jeff Merkley (D-Ore.), which would reduce the sale of single-use plastics in national parks. It also advocated for the Plastic Pellet Free Waters Act, introduced last year by Rep. Mike Levin (D-Calif.) and then-Rep. Mary Peltola (D-Alaska), which would prohibit the discharge of pre-production plastic pellets into waterways, storm drains, and sewers.

“It’s time that our elected officials act on the warnings we’ve raised for years—single-use plastics and microplastics pose an immediate threat to our environment and public health,” said Paulita Bennett-Martin, senior strategist of policy initiatives at 5 Gyres. “TrashBlitz volunteers uncovered thousands of microplastics in our nation’s most protected spaces, and we’re urging decisive action that addresses this issue at the source.”

Microplastics filter inspired by fish

Researchers at the University of Bonn want to make wastewater cleaner

University of Bonn

Inside the mouth — image:
of this anchovy, plankton particles are captured by the gill arch system.
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Credit: Photo: Jens Hamann

Wastewater from washing machines is considered a major source of microplastics – tiny plastic particles that are suspected of harming human and animal health. Researchers at the University of Bonn now have developed a filter to curb this problem. Their filter was inspired by the gill arch system in fish. In initial tests, the now patent-pending filter was able to remove over 99 percent of plastic fibers from washing machine wastewater. The results now have been published in the journal npj Emerging Contaminants.

Wastewater from a washing machine in a four-person household produces up to 500 grams of microplastics each year, mainly caused by textile abrasion. The household appliances are thus one of the most important sources of the tiny particles. Microplastics currently make their way directly into the sewage sludge of wastewater treatment plants. As this sludge is often used as fertilizer, the fibers ultimately end up on the fields.

Many manufacturers have thus been searching for ways to remove microplastics from washing water to prevent them from entering the environment. “The filter systems available so far, however, have various disadvantages,” explains Dr. Leandra Hamann from the Institute for Organismic Biology at the University of Bonn. “Some of them quickly become clogged, others do not offer adequate filtration.”

Looking inside the mouths of fish

The scientist, alongside her doctoral supervisor Dr. Alexander Blanke and colleagues, has thus turned to the animal kingdom in her search for possible solutions. The team focused on fish that can be considered true masters of filter technology – and have evolved this filtration over hundreds of millions of years.

Some fish feed by means of filtration; these include, for example, mackerel, sardines, and anchovies. They swim through the water with their mouths open and sift out the plankton with their gill arch system. “We took a closer look at the construction of this system and used it as the model for developing a filter that can be used in washing machines,” says Blanke, who is a member of the transdisciplinary research areas “Life & Health” and “Sustainable Futures” at the University of Bonn.

During their evolution these fish have developed a technique similar to cross-flow filtration. Their gill arch system is shaped like a funnel that is widest at the fish’s mouth and tapers towards their gullet. The walls of the funnel are shaped by the branchial arches. These feature comb-like structures, the arches, which are themselves covered in small teeth. This creates a kind of mesh that is stretched by the branchial arches.

Self-cleaning: plankton rolls towards the gullet

“During food intake, the water flows through the permeable funnel wall, is filtered, and the particle-free water is then released back into the environment via the gills,” explains Blanke. “However, the plankton is too big for this; it is held back by the natural sieve structure. Thanks to the funnel shape, it then rolls towards the gullet, where it is collected until the fish swallows, which empties and cleans the system.”

This principle prevents the filter from being blocked – instead of hitting the filter head-on, the fibers roll along it towards the gullet. The process is also highly effective, as it removes almost all of the plankton from the water. Both are aspects that a microplastic filter must also be able to deliver. The researchers thus replicated the gill arch system. In doing so, they varied both the mesh size of the sieve structure and the opening angle of the funnel.

Filter achieves high efficiency

“We have thus found a combination of parameters that enable our filter to separate more than 99 percent of the microplastics out of the water but not become blocked,” says Hamann. To achieve this, the team used not only experiments but also computer simulations. The filter modelled on nature does not contain any elaborate mechanics and should thus be very inexpensive to manufacture.

The microplastics that it filters out of the washing water collect in the filter outlet and are then suctioned away several times a minute. According to the researcher, who has now moved to the University of Alberta in Edmonton, Canada, they could then, for example, be pressed in the machine to remove the remaining water. The plastic pellet created in this manner could then be removed every few dozen washes and disposed of with general waste.

The team from the University of Bonn and the Fraunhofer Institute for Environmental, Safety, and Energy Technology UMSICHT has already applied for a patent for its development in Germany; EU-wide patenting is currently underway. The researchers now hope that manufacturers will further develop the filter and integrate it into future generations of washing machines. This would stem the spread of microplastics from textiles, at least to some extent. And that is also necessary: analyses indicate that the particles may cause serious damage to health. They have already been found in breast milk and in the placenta – and even in the brain.

Participating institutions and funding:

In addition to the University of Bonn, the Fraunhofer Institute for Environmental, Safety, and Energy Technology UMSICHT was also involved in the study. The work was supported with funding from the Federal Ministry of Research, Technology and Space (BMFTR) and the European Research Council (ERC). The protection and marketing of the invention is supported by the Transfer Center enaCom at the University of Bonn in close cooperation with PROvendis GmbH, a service provider of the NRW university network for knowledge and technology transfer “innovation2business.nrw.”

Publication: Leandra Hamann et. al. (2025): A self-cleaning, bio-inspired high retention filter for a major entry path of microplastics; npj Emerging Contaminants; DOI: https://doi.org/10.1038/s44454-025-00020-2

the gill rakers are covered with denticles forming a mesh structure that catches the particles.

Credit

Photo: Leandra Hamann

imitates the gill arch system of the fish. The filter housing enables periodic cleaning and installation in washing machines.

Credit

Illustration: Christian Reuß/Leandra Hamann

front Dr. Leandra Hamann, right Dr. Alexander Blanke, center material researcher Christian Reuß, left biologist Dr. Hendrik Herzog.

Credit

Photo: Peter Rühr/Uni Bonn

DOI

10.1038/s44454-025-00020-2