Biotic and Abiotic Interactions in Aquatic Microcosms Determine Fate and Toxicity of Ag Nanoparticles. Part 1. Aggregation and Dissolution

• Published in: Environmental science & technology Vol. 46; no. 13; pp. 6915 - 6924
• Main Authors: Unrine, Jason M, Colman, Benjamin P, Bone, Audrey J, Gondikas, Andreas P, Matson, Cole W
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 03.07.2012
• Subjects: Animal, plant and microbial ecology; Applied ecology; Applied sciences; Aquatic plants; Biological and medical sciences; Biological and physicochemical phenomena; Earth sciences; Earth, ocean, space; Ecotoxicology, biological effects of pollution; Engineering and environment geology. Geothermics; Exact sciences and technology; Fresh Water - chemistry; Fundamental and applied biological sciences. Psychology; General aspects; Geologic Sediments - analysis; Gum Arabic - chemistry; Gum Arabic - metabolism; Gum Arabic - toxicity; Mass spectrometry; Nanoparticles; Nanoparticles - chemistry; Nanoparticles - toxicity; Natural water pollution; Plants - metabolism; Pollution; Pollution, environment geology; Povidone - chemistry; Povidone - metabolism; Povidone - toxicity; Sediments; Silver - chemistry; Silver - metabolism; Silver - toxicity; Solubility; Surface water; Toxicity; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - metabolism; Water Pollutants, Chemical - toxicity; Water treatment and pollution; Emerging contaminant; Coating material; Stability; Pollutant behavior; Nanoparticle; Gum arabic; Dissolution; Heavy metal; Aggregation; Trace element; Aquatic environment; Silver; Dissolved organic matter; Pyrrolidone(vinyl) polymer; Ecosystem; Coated particle; Water pollution; Biocide; Nanostructured materials; Nanotechnology; Organic compounds
• DOI: 10.1021/es204682q
• ISSN: 0013-936X

To better understand their fate and toxicity in aquatic environments, we compared the aggregation and dissolution behavior of gum arabic (GA) and polyvinylpyrrolidone (PVP) coated Ag nanoparticles (NPs) in aquatic microcosms. There were four microcosm types: surface water; water and sediment; water and aquatic plants; or water, sediment, and aquatic plants. Dissolution and aggregation behavior of AgNPs were examined using ultracentrifugation, ultrafiltration, and asymmetrical flow field flow fractionation coupled to ultraviolet–visible spectroscopy, dynamic and static laser light scattering, and inductively coupled plasma mass spectrometry. Plants released dissolved organic matter (DOM) into the water column either through active or passive processes in response to Ag exposure. This organic matter fraction readily bound Ag ions. The plant-derived DOM had the effect of stabilizing PVP-AgNPs as primary particles, but caused GA-AgNPs to be removed from the water column, likely by dissolution and binding of released Ag ions on sediment and plant surfaces. The destabilization of the GA-AgNPs also corresponded with X-ray absorption near edge spectroscopy results which suggest that 22–28% of the particulate Ag was associated with thiols and 5–14% was present as oxides. The results highlight the potential complexities of nanomaterial behavior in response to biotic and abiotic modifications in ecosystems, and may help to explain differences in toxicity of Ag observed in realistic exposure media compared to simplified laboratory exposures.