Silver Nanoparticles May Form in Nature

Humic acid, which reacts with calcium carbonate in rocks, may also react with silver ions to form nanoparticles photo

Image: Humic Acids as a Force of Nature, thotfulspot/CC

Silver nanoparticles are turning up everywhere: from your socks (antimicrobial) to your solar panels (nanoparticle ink). At least one study has shown that the tiny dots of silver can cause dramatic mutations in fish. A new study demonstrates processes by which silver nanoparticles may be created from silver ions in nature. If silver nanoparticles are "natural," does that let them off the risk-management hook?A team lead by Nelson Akaighe of the Florida Institute of Technology (FIT), with colleagues from the State University of New York (SUNY), Buffalo, and the National Institute of Standards and Technology (NIST) published the study Humic Acid-Induced Silver Nanoparticle Formation Under Environmentally Relevant Conditions in the Journal Environmental Science & Technology.

In the paper, the team describes how they demonstrated a process by which silver nanoparticles could occur naturally. In the presence of humic acids, which is a collective term for a number of acids formed when organic matter decays in sediments or soils, silver ions are reduced to silver particles. As the silver particles clump into nanoparticles, the humic acids coat them and prevent further clumping to form massive silver. This finding could help explain the detection of silver nanoparticles near abandoned mines, where man-made nanoparticles could not be expected to be found.

If silver nanoparticles can form naturally, does that let them off the hook as potential environmental contaminants? No way! Research to determine the risks, and regulation to balance the benefits, remains necessary in the field of nanotechnology.

Instead, the finding suggests that releases of silver in ionic form need to be studied for effects on the pathway of nanoparticle formation among the other "fate and pathway" studies currently existing. The research also means that measurements of silver nanoparticle concentrations in the environment may not have a one-to-one relationship with releases of man-made silver nanoparticles, which further complicates the detection and control of environmental impacts from anthropogenic activities (and increases the industrial-pollutant deniability factor).

More on Nanoparticles:
Nano Particles or No-No Particles
Killer Paper Introduces Another Application for Silver Nanoparticles
New Biocide Research Pits Stinky Feet Against Fish
Beware The Silver Lining: A Risk Management Review Of Commercial Nanotechnology

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