Scientists trace microplastics in fertilizer from fields to the beach

First steps in tracing major pollutant source in “missing plastics” problem

Tokyo Metropolitan University

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Fate of microplastics in PCFs. Of polymer-coated fertilizer capsules used in paddies, 77% stay there and only 0.2% are estimated to end up on the beach, leaving 22.8% “missing” plastic waste.

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Credit: Tokyo Metropolitan University

Tokyo, Japan – Researchers from Tokyo Metropolitan University have studied how polymer-coated fertilizer (PCF) applied to fields ends up on beaches and in the sea. They studied PCF deposits on beaches around Japan, finding that only 0.2% of used PCFs are washed into rivers and returned to the coastline. When there are canals connecting fields to the sea, this rises to 28%. Their findings highlight a potentially significant “sink” in the global circulation of plastics.

 

Plastic marine pollution poses a serious threat to wildlife, ecosystems, and human health. It is estimated that around 90% of the plastic that has flowed out to sea has disappeared from the sea surface, accumulated on the sea floor or any number of other “sinks.” To effectively reduce the amount of “missing plastics,” scientists have been studying the complex ways by which plastic material is transported from its point of use to the sea.

Polymer-coated fertilizer (PCF) is a major source of microplastic pollution. Certain fertilizers are coated in a thin layer of plastic to delay the release of chemicals, making it last longer. They are widely used in Japan and China for rice cultivation, as well as for wheat, corn, and other crops in the U.S., U.K., and Western Europe. In fact, it has been shown that 50-90% of plastic debris found on beaches in Japan is derived from PCFs. Yet, the way in which PCFs are carried from land to sea, and how that affects its eventual disappearance, is not well understood.

A team of researchers from Tokyo Metropolitan University, led by Professor Masayuki Kawahigashi and Dr. Dolgormaa Munkhbat, surveyed the amount of PCFs ending up on beaches across different environments. They focused on beaches near river mouths and direct drainage points from agricultural fields to the sea, surveying 147 plots across 17 beaches. Near river mouths, they estimated that the PCFs found on beaches there amount to less than 0.2% of what was used in surrounding areas. With 77% staying on fields, the remaining 22.8% wash out to sea. On the other hand, surveys around direct drainage points from agricultural land to the sea showed that 28% end up back on the beach. The team concluded that waves and tidal action help them wash back onto land, making beaches a temporary sink for microplastics. Given that most PCFs lost from fields end up in rivers, the majority of these plastic capsules end up going “missing.”

The team also noticed that many of the PCF microplastics they found showed significant reddening and browning. Analysis with Energy-Dispersive X-ray Spectroscopy (EDX) revealed newly added particles of iron and aluminum oxide, which may be weighing the capsules down, making them less likely to wash back to shore. While many challenges remain in understanding the complex transport of a major pollutant, the team’s survey is a key first step in tracing how PCFs contribute to the global challenge of missing plastics.

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Journal

Marine Pollution Bulletin

DOI

10.1016/j.marpolbul.2025.119086 

Article Title

A first approach to estimate the leakage of polymer-coated fertilizer-derived microplastics from paddy fields to beaches

 

Triple threat in greenhouse farming: how

 heavy metals, microplastics, and antibiotic

 resistance genes unite to challenge

 sustainable food production

Biochar Editorial Office, Shenyang Agricultural University

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Composite contaminations dilemma in facility agriculture: pollution characteristics, risk assessment, and sustainable control strategies

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Credit: Zhengzhe Fan, Ruolan Li, Yinuo Ding, Qifan Yang, Wei Liu, Houyu Li, & Yan Xu

Invisible pollutants in high tech greenhouses may be quietly reshaping the food on our plates and the soil beneath our feet. A new open access review maps how heavy metals, micro and nanoplastics, and antibiotic resistance genes increasingly pile up together in intensive “facility agriculture” and why this triple cocktail demands urgent attention from scientists, farmers, and regulators.

The paper reviews composite pollution in facility agriculture, a fast growing form of high yield farming that relies on greenhouses and other controlled environments to produce vegetables and other crops year round. The authors focus on three typical contaminants heavy metals, micro and nanoplastics, and antibiotic resistance genes that now frequently co occur and interact in these systems.​

Facility agriculture uses large amounts of fertilizers, pesticides, plastic films, and animal manure, all within relatively enclosed spaces. Over time this leads to much higher levels of pollutants in greenhouse soils than in open fields and increases the chance that different contaminants will combine and reinforce each other rather than acting alone.​

Why composite contamination matters

The review shows that heavy metals, microplastics, and resistance genes rarely appear in isolation in modern greenhouse soils. Instead they cluster in regional hotspots such as parts of Europe and East Asia and can reach levels that affect soil organisms, crop growth, and eventually consumers through the food chain.​

When these pollutants combine, their joint effects can be more harmful than the impact of each pollutant on its own. For example, microplastics can carry heavy metals and resistance genes deeper into soil or into plant tissues, while heavy metals can speed up the evolution and spread of antibiotic resistance in soil microbes.​

Key findings on risks and mechanisms

According to the review, microplastics from aging greenhouse films can raise soil microplastic levels by roughly half or more compared with conventional mulching, while long term fertilizer use increases residual heavy metals and animal manure inputs fuel the expansion of resistance genes in soil. Together these factors create a persistent “composite contamination” background in intensively managed fields.​

At the microscopic level, plastics provide large reactive surfaces where metal ions can bind and biofilms can form, turning each particle into a mobile platform for both chemicals and microbes. Heavy metals and resistance genes often occur on the same genetic elements, so metal stress alone can favor bacteria that also carry resistance to antibiotics, even when antibiotics are not present.​

Gaps in current risk assessment

The authors argue that current pollution indices and health risk models were mostly designed for single pollutants and struggle to capture the combined ecological and health risks of multi pollutant exposure. Existing tools can estimate contamination levels or human health risks but rarely consider dynamic interactions among multiple contaminants across soil, water, crops, and air at the same time.​

They call for new multi scenario assessment frameworks that integrate data from several models, follow pollution over time, and link numerical indices directly to real world outcomes such as crop performance, soil function, and local health indicators.​

Towards cleaner and safer greenhouse farming

The review also evaluates physical chemical, biological, and management based strategies that could help control composite contamination in facility agriculture. Options range from soil replacement and chemical leaching to microbial and plant based remediation and smarter field management using biodegradable films, improved manure treatment, and optimized crop rotations.​

Each strategy has trade offs: rapid physical or chemical interventions can be effective but costly and disruptive, while biological and management approaches are often cheaper and more sustainable but slower and sensitive to local conditions. The authors suggest that combining greener materials, engineered microbial communities, and precision digital monitoring could offer more sustainable long term solutions for protecting soil health, food safety, and the broader “One Health” links between ecosystems, animals, and people.​

 

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Journal reference: Fan Z, Li R, Ding Y, Yang Q, Liu W, et al. 2025. Composite contaminations dilemma in facility agriculture: pollution characteristics, risk assessment, and sustainable control strategies. Biocontaminant 1: e023  

https://www.maxapress.com/article/doi/10.48130/biocontam-0025-0024  

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About Biocontaminant:
Biocontaminant (e-ISSN: 3070-359X) is a multidisciplinary platform dedicated to advancing fundamental and applied research on biological contaminants across diverse environments and systems. The journal serves as an innovative, efficient, and professional forum for global researchers to disseminate findings in this rapidly evolving field.

Follow us on Facebook, X, and Bluesky. 

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DOI

10.48130/biocontam-0025-0024 

Method of Research

Literature review

Subject of Research

Not applicable

Article Title

Composite contaminations dilemma in facility agriculture: pollution characteristics, risk assessment, and sustainable control strategies

Environmental “superbugs” in our rivers and soils: new one health review warns of growing antimicrobial resistance crisis

Biochar Editorial Office, Shenyang Agricultural University

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Environmental antimicrobial resistance: key reservoirs, surveillance and mitigation under One Health

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Credit: Huilin Zhang, Yuqiu Luo, Xinyu Zhu & Feng Ju

Environmental antimicrobial resistance is turning rivers, soils, and even the air into hidden highways for “superbugs,” according to a new review that calls for urgent, coordinated action across human, animal, and environmental health. The authors argue that protecting people from drug resistant infections now depends as much on wastewater plants and farms as it does on hospitals.

A growing environmental “superbug” crisis

Antimicrobial resistance (AMR) occurs when bacteria and other microbes evolve the ability to survive medicines that once killed them, making common infections harder or impossible to treat. The World Health Organization already lists AMR as one of the most serious global health threats of this century, with some estimates warning of tens of millions of deaths and massive economic losses if action fails.​

The new study shows that the environment is not just a passive backdrop. Rivers, lakes, soils, oceans, and even air can carry resistance genes and resistant bacteria that move between wildlife, livestock, and people, helping create a truly global network of AMR.​

Key sources and hidden reservoirs

The review highlights several major environmental “hotspots” where resistance builds up and spreads.​

• Hospital and city wastewater treatment plants act as central mixing hubs, collecting antibiotic residues, resistant pathogens, and mobile genetic elements from homes and clinics. Conventional treatment often fails to fully remove these contaminants, allowing resistance genes to persist in effluent water and sewage sludge.​

• Livestock farms and aquaculture systems use large quantities of antibiotics, enriching resistance genes in animal gut microbes and manure that then reach soils, crops, and surrounding waters.​

• Pharmaceutical manufacturing facilities can discharge extremely high levels of both antibiotics and resistance genes, raising the risk that dangerous resistance traits spread downstream.​

Across these sites, resistance genes can hitchhike on mobile genetic elements such as plasmids, making it easier for bacteria to “swap” resistance traits and create multidrug resistant strains.​

Why traditional monitoring is not enough

Most AMR surveillance still focuses on clinical samples, but the authors argue that environmental monitoring needs to catch up. Classic culture based tests remain important because they measure whether bacteria actually survive antibiotics, and they provide live isolates for further study. However, many environmental bacteria cannot be grown easily in the lab, and these methods can miss most of the resistance present.​

Newer tools are rapidly changing the picture:

• Phenotypic methods such as flow cytometry and Raman spectroscopy can track resistant cells and gene transfer in complex samples within hours, without requiring cultivation.​

• Genotypic methods such as high throughput quantitative PCR, CRISPR based assays, and metagenomic sequencing can detect hundreds of resistance genes at once, and identify which bacteria carry them.​

• Long read sequencing now allows researchers to reconstruct entire mobile genetic elements and see exactly how resistance genes are organized and move between hosts.​

“The message is clear” said lead author Huilin Zhang. “No single method can capture the full story of environmental resistance. What we need is integrated surveillance that links what bacteria can do to what genes they carry, and where they are spreading.”​

One Health and smarter mitigation

The review is framed within the One Health concept, which emphasizes that human, animal, and environmental health are tightly connected. The authors propose tackling AMR on two fronts source control to reduce the amount of antibiotics, resistant bacteria, and resistance genes entering the environment, and process control to intercept them along key pathways such as wastewater treatment.​

Source control measures include stricter antibiotic stewardship in medicine and agriculture, better regulation in low and middle income regions, and cleaner production in pharmaceutical industries. The authors also highlight emerging “green” solutions, such as enhanced biodegradation of antibiotics, design of more biodegradable drugs, and alternative antimicrobials like peptides and phages.​

On the process side, improved wastewater treatment and waste management are crucial. Conventional disinfection can reduce many resistant bacteria but may leave resistance genes intact, especially in solid waste streams. More advanced approaches such as hyperthermophilic composting, advanced oxidation, membrane processes, nanomaterials, bacteriophage based treatments, engineered DNA scavenging bacteria, and CRISPR based tools show promise but require further research, safety evaluation, and cost reduction.​

Focusing on the riskiest resistance

Instead of simply counting how many resistance genes exist, the authors argue that surveillance and policy should prioritize traits that really drive health risk. Three stand out:​

• Mobility: how easily genes move between bacteria and environments.​

• Host pathogenicity: whether the bacterial hosts are capable of causing disease in humans or animals.​

• Multi resistance: whether genes and their hosts resist multiple key antibiotics, limiting treatment options.​

“Environmental AMR is not just about how many resistance genes we can find” said corresponding author Feng Ju. “What matters most is which genes are mobile, which pathogens carry them, and how they evolve in real world ecosystems. That is where surveillance must focus, and where mitigation will have the biggest impact.”​

The authors call for global, standardized protocols that make environmental AMR data comparable across countries and over time. Without such standards, they warn, the world will struggle to spot emerging threats early enough and to design effective One Health interventions that protect both people and the planet.​

 

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Journal reference: Zhang H, Luo Y, Zhu X, Ju F. 2025. Environmental antimicrobial resistance: key reservoirs, surveillance and mitigation under One Health. Biocontaminant 1: e022  

https://www.maxapress.com/article/doi/10.48130/biocontam-0025-0023  

=== 

About Biocontaminant:
Biocontaminant (e-ISSN: 3070-359X) is a multidisciplinary platform dedicated to advancing fundamental and applied research on biological contaminants across diverse environments and systems. The journal serves as an innovative, efficient, and professional forum for global researchers to disseminate findings in this rapidly evolving field.

Follow us on Facebook, X, and Bluesky. 

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DOI

10.48130/biocontam-0025-0023 

Method of Research

Literature review

Subject of Research

Not applicable

Article Title

Environmental antimicrobial resistance: key reservoirs, surveillance and mitigation under One Health