Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Persistence of Singly Dispersed Silver Nanoparticles in Natural Freshwaters, Synthetic Seawater, and Simulated Estuarine Waters



Stephanie L. Chinnapongse, Robert I. MacCuspie, Vincent A. Hackley


The use of silver nanoparticles (AgNPs) in consumer products has become increasingly widespread over the past decade. These products are being used and distributed world-wide, creating a risk of AgNPs flowing into rivers and oceans via wastewater. Though AgNPs are desirable for their antimicrobial properties, their dissolution to more soluble Ag(I) species in aqueous media has raised concerns about human and environmental safety. Recent literature on AgNP behavior is limited on the colloidal stability under environmentally relevant conditions, indicating that many of these effects have not been quantitatively studied and leaves the question unanswered of whether AgNPs themselves pose novel toxicity risks. This paper focuses on the persistence and colloidal stability of AgNPs in natural freshwaters and lab-prepared synthetic waters to assesses the potential risk AgNPs may have on aquatic environments. Ultraviolet-visible spectroscopy, dynamic light scattering, and atomic force microscopy were used to evaluate the colloidal stability of the AgNPs in locally-obtained pond water, moderately hard reconstituted water alone or with natural organic matter, synthetic seawater, and also the individual chemicals most prevalent in seawater. Singly dispersed AgNPs in seawater and samples with greater than 20 mmol•L-1 sodium chloride were unstable, with the absorbance approaching zero within the first ten hours of mixing. Other samples, mostly those with lower salinity, maintained varying degrees of colloidal stability during time studies up to 48 h. This indicated greater availability of AgNPs in freshwater, and also likelihood that some AgNPs will be stable long enough in freshwater to successfully enter estuarine or marine systems. While these studies show that AgNPs have a definite potential to affect both fresh and saltwater systems, many steps are left to be taken to obtain a thorough risk assessment of AgNPs in the environment. The results of this work should enable
Science of the Total Environment


Silver nanoparticle persistence, colloidal stability, nanoparticle dispersions, environmental fate of silver nanoparticles


Chinnapongse, S. , MacCuspie, R. and Hackley, V. (2011), Persistence of Singly Dispersed Silver Nanoparticles in Natural Freshwaters, Synthetic Seawater, and Simulated Estuarine Waters, Science of the Total Environment, [online], (Accessed June 18, 2024)


If you have any questions about this publication or are having problems accessing it, please contact

Created April 27, 2011, Updated October 12, 2021