How metals, organics, and microbes shape iron nanoparticles in nature

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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