How metals, organics, and microbes shape iron nanoparticles in nature
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Review on formation of iron (oxyhydr)oxide nanoparticles in the environment: interactions with metals, organics and microbes
view moreCredit: Zhixiong Li, Thomas L. Goût & Yandi Hu
A new review published in Environmental and Biogeochemical Processes reveals how tiny iron oxyhydroxide nanoparticles, among the most abundant nanoparticles in soils and water, form and interact with metals, organic matter, and microbes, profoundly shaping Earth’s environment.
These iron nanoparticles play major roles in ecosystem health by cycling key elements, influencing pollutant movement, and helping regulate the chemistry of natural waters and soils. Although they are essential, understanding how these particles develop and transform in the environment has been a challenging scientific question.
Researchers from Peking University and the China University of Geosciences compiled the latest advances to show that iron nanoparticles form in two main ways. They can form directly from dissolved substances in water or assemble on the surfaces of minerals, organic matter, or microbial biofilms. The review explains that metal ions in water, such as aluminum, chromium, and copper, significantly affect the early stages of nanoparticle growth by binding to surfaces or entering the particles’ structures. These effects can change both the shape and stability of the nanoparticles, which in turn influences how long they last and where they migrate in the environment.
Organic molecules, especially those present in natural waters and soils, also play a major role. These molecules can cap iron particles, leading to smaller, less crystalline structures, or they can bind iron in ways that change where and how particles form. Humic substances and organic acids often direct iron to remain as nanoparticles rather than join to form larger crystals, affecting how heavy metals and other pollutants are retained or transported.
Microbes such as iron-oxidizing bacteria add another layer of complexity. They process iron chemically and secrete sticky substances that offer a template for iron nanoparticle growth. This means microbes can create unique forms of nanoparticles and influence the fate of important nutrients and contaminants in soils and water.
Understanding these complex processes is key for predicting the movement of pollutants, supporting safer water supplies, and creating new cleanup technologies. The review also notes how newer imaging and spectroscopy tools are enabling scientists to track nanoparticle formation in real time, providing insights important for environmental protection as conditions change with the climate.
This integrated perspective opens new directions in environmental science. It brings attention to the world of nanominerals and their essential roles in maintaining healthy ecosystems and safe, clean water.
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Journal reference: Li Z, Goût TL, Hu Y. 2025. Review on formation of iron (oxyhydr)oxide nanoparticles in the environment: interactions with metals, organics and microbes. Environmental and Biogeochemical Processes 1: e003 https://www.maxapress.com/article/doi/10.48130/ebp-0025-0005
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About the Journal:
Environmental and Biogeochemical Processes is a multidisciplinary platform for communicating advances in fundamental and applied research on the interactions and processes involving the cycling of elements and compounds between the biological, geological, and chemical components of the environment.
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Method of Research
Literature review
Subject of Research
Not applicable
Article Title
Review on formation of iron (oxyhydr)oxide nanoparticles in the environment: interactions with metals, organics and microbes
New biochar technology promises breakthrough in soil clean-up and crop safety
Biochar Editorial Office, Shenyang Agricultural University
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P-modified biochar alters the microbial community in heavy metal-contaminated soils by regulating nutrient supply balance
Credit: Qiang Wang, Chenyang Xu, Kai Pan, Xiaogang Wu, Yanshuo Pan, Chengjiao Duan & Zengchao Geng
Scientists have unveiled a pioneering method that could help farmers reclaim lands blighted by toxic metals and boost the safety of crops grown in contaminated soils. The study, led by a research team in China, reveals that phosphorus-modified biochar, a carbon-rich material derived from apple tree branches—can dramatically reduce the threat posed by heavy metals in agricultural soils near mining areas.
Heavy metal pollution from industrial activity remains a global threat to food safety, as toxic elements like cadmium and lead can accumulate in crops and enter the human food chain. While traditional biochar has been used to remediate soils, its effectiveness in removing heavy metals has been limited. Researchers overcame this hurdle by modifying biochar with phosphorus, resulting in a powerful soil amendment that not only immobilizes harmful metals but also improves soil quality.
In greenhouse experiments, the scientists added the new biochar formulation to heavily polluted soils growing maize. The results were striking: the levels of toxic heavy metals available for plant uptake dropped by over 28%. Cadmium and lead levels in maize grains themselves were reduced by 36% and 62%, respectively. “This indicates real potential to reduce health risks for consumers and livestock,” the researchers noted.
But the innovation goes further. The phosphorus-modified biochar changed the makeup of beneficial soil bacteria and fungi, regulating the soil’s supply of essential nutrients like nitrogen and phosphorus. These changes helped build healthier microbial communities, which are vital for long-term soil fertility and resilience. Interestingly, the reduction in metal toxicity was not the main factor in altering these microbial communities—rather, it was the improved nutrient balance that played the leading role.
The study’s findings highlight a promising and practical approach for cleaning up heavy metal–tainted farmland and securing the food supply in affected regions. As the team emphasizes, further field trials are needed to confirm the technology’s effectiveness under real-world agricultural conditions.
This work opens new doors for cost-effective, environmentally friendly restoration of polluted soils, offering fresh hope for farmers and communities worldwide.
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Journal Reference: Wang, Q., Xu, C., Pan, K. et al. P-modified biochar alters the microbial community in heavy metal-contaminated soils by regulating nutrient supply balance. Biochar 7, 93 (2025). https://doi.org/10.1007/s42773-025-00495-7
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About Biochar
Biochar is the first journal dedicated exclusively to biochar research, spanning agronomy, environmental science, and materials science. It publishes original studies on biochar production, processing, and applications—such as bioenergy, environmental remediation, soil enhancement, climate mitigation, water treatment, and sustainability analysis. The journal serves as an innovative and professional platform for global researchers to share advances in this rapidly expanding field.
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Journal
Biochar
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
P-modified biochar alters the microbial community in heavy metal-contaminated soils by regulating nutrient supply balance
Straw, soil, and lead: How climate cycles shape the fate of heavy metals in farmland
Dr. Song Cui (Northeast Agricultural University) and Dr. Yongzhen Ding (Agro-Environmental Protection Institute) reveal how freeze-thaw and wet-dry cycles control pollution risks in straw-amended soils
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Compositional evolution of dissolved organic matter mobilized by straw incorporation and its climate-driven interactions with lead in cold-region black soil: decoding mechanisms through PARAFAC and complexation modeling
view moreCredit: Song Cui, Lu Liu, Fuxiang Zhang, Qiang Fu, Chao Ma & Yongzhen Ding
You might think adding crop straw to soil is a no-brainer: it enriches the earth, boosts organic matter, and supports sustainable farming. But what if the weather could turn this green practice into a hidden risk for heavy metal pollution? A groundbreaking new study, published on August 1, 2025, in Carbon Research—has uncovered the complex, climate-driven dance between straw incorporation, soil organic matter, and lead (Pb) mobility. And the results are reshaping how we think about safe soil remediation in a changing climate. Led by Dr. Song Cui from the International Joint Research Center for Persistent Toxic Substances (IJRC-PTS) and Research Center for Eco-Environment Protection of Songhua River Basin, Northeast Agricultural University, Harbin, China, in collaboration with Dr. Yongzhen Ding from the Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin, China, this research dives deep into the invisible world of dissolved organic matter (DOM)—and how it can either lock away or unleash toxic metals.
The Straw Paradox: Good for Soil, Risky for Metals?
In theory, adding straw to soil is a win-win: it improves fertility, increases carbon storage, and enhances microbial life. But when heavy metals like lead (Pb) are already present in contaminated farmland, things get complicated. Why? Because straw decomposition releases dissolved organic matter (DOM)—a powerful player that can bind to metals and influence whether they stay put or leach into groundwater. And here’s where climate comes in: freeze-thaw (FT) and wet-dry (WD) cycles, common in temperate and monsoon regions, are not just weather patterns. They’re soil game-changers.
Freeze-Thaw vs. Wet-Dry: Opposite Effects on Pollution Risk
The team used advanced techniques like PARAFAC fluorescence analysis and complexation modeling to track DOM changes and Pb behavior under different aging conditions. The findings? Striking—and actionable.
Freeze-Thaw Cycles (Winter-like conditions):
- Reduced acid-soluble Pb (the most bioavailable, risky form) by 13.6% in straw-amended soils and 11.6% in unamended soils
- Helped stabilize Pb, likely by promoting aggregation and reducing DOM mobility
- A climate buffer against metal remobilization
Wet-Dry Cycles (Summer monsoon or drought-prone conditions):
- Increased acid-soluble Pb by 51.8% in straw-amended soils (and 30.7% in controls)
- Enhanced DOM release, especially highly aromatic compounds that strongly bind Pb but can also transport it
- A potential pollution accelerator under humid-dry fluctuation
The DOM-Pb Tango: Who’s Leading?
Not all DOM is the same. Using PARAFAC, researchers identified three key humic-like fluorescent components (Peak A, C, and D), each with distinct Pb-binding strengths.
- Highly aromatic DOM, more abundant under wet-dry cycles, formed stronger complexes with Pb (stability constants lg K = 4.3–4.5)
- Compared to freeze-thaw soils (lg K = 3.3–3.9), meaning Pb was more tightly—but potentially more mobilizably—bound
“In wet-dry environments, DOM acts like a taxi for lead,” explains Dr. Cui. “It doesn’t just bind Pb—it can shuttle it through the soil, increasing the risk of uptake by crops or leaching into water.”
Why This Matters for Farmers and Policymakers
This study is a wake-up call: straw return is not one-size-fits-all. In regions with frequent wet-dry fluctuations, like southern China or monsoon-affected agricultural zones, adding straw without caution could increase heavy metal bioavailability. But in cold temperate zones with regular freeze-thaw cycles, straw incorporation may actually help stabilize contaminants.
A Blueprint for Climate-Smart Soil Remediation
The research provides a critical framework for optimizing organic amendments in contaminated lands:
- Match straw use to local climate patterns
- Monitor DOM quality, not just quantity
- Prioritize soil stabilization strategies in wet-dry regions (e.g., co-application with biochar or clay minerals)
“This isn’t about stopping straw return,” says Dr. Ding. “It’s about doing it smarter—protecting both soil health and food safety in the era of climate change.”
Celebrating Innovation in Agro-Environmental Science
This work highlights the leadership of Northeast Agricultural University—especially its IJRC-PTS and Songhua River Basin Research Center—in addressing pressing eco-environmental challenges. It also underscores the vital role of national institutes like the Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, in bridging science and policy.
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- Title: Compositional evolution of dissolved organic matter mobilized by straw incorporation and its climate-driven interactions with lead in cold-region black soil: decoding mechanisms through PARAFAC and complexation modeling
- Keywords: Straw incorporation; Dissolved organic matter; Spectral characteristics; Heavy metals; Binding ability
- Citation: Cui, S., Liu, L., Zhang, F. et al. Compositional evolution of dissolved organic matter mobilized by straw incorporation and its climate-driven interactions with lead in cold-region black soil: decoding mechanisms through PARAFAC and complexation modeling. Carbon Res. 4, 56 (2025). https://doi.org/10.1007/s44246-025-00225-5
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About Carbon Research
The journal Carbon Research is an international multidisciplinary platform for communicating advances in fundamental and applied research on natural and engineered carbonaceous materials that are associated with ecological and environmental functions, energy generation, and global change. It is a fully Open Access (OA) journal and the Article Publishing Charges (APC) are waived until Dec 31, 2025. It is dedicated to serving as an innovative, efficient and professional platform for researchers in the field of carbon functions around the world to deliver findings from this rapidly expanding field of science. The journal is currently indexed by Scopus and Ei Compendex, and as of June 2025, the dynamic CiteScore value is 15.4.
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Journal
Carbon Research
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
Compositional evolution of dissolved organic matter mobilized by straw incorporation and its climate-driven interactions with lead in cold-region black soil: decoding mechanisms through PARAFAC and complexation modeling
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