Emerging contaminant or an old toxin in disguise? Silver nanoparticle impacts on ecosystems.


The use of antimicrobial silver nanoparticles (AgNPs) in consumer-products is rising. Much of these AgNPs are expected to enter the wastewater stream, with up to 10% of that eventually released as effluent into aquatic ecosystems with unknown ecological consequences. We examined AgNP impacts on aquatic ecosystems by comparing the effects of two AgNP sizes (12 and 49 nm) to ionic silver (Ag(+); added as AgNO3), a historically problematic contaminant with known impacts. Using 19 wetland mesocosms, we added Ag to the 360 L aquatic compartment to reach 2.5 mg Ag L(-1). Silver treatments and two coating controls were done in triplicate, and compared to four replicate controls. All three silver treatments were toxic to aquatic plants, leading to a significant release of dissolved organic carbon and chloride following exposure. Simultaneously, dissolved methane concentrations increased forty-fold relative to controls in all three Ag treatments. Despite dramatic toxicity differences observed in lab studies for these three forms of Ag, our results show surprising convergence in the direction, magnitude, and duration of ecosystem-scale impacts for all Ag treatments. Our results suggest that all forms of Ag changed solute chemistry driving transformations of Ag which then altered Ag impacts.





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Publication Info

Colman, Benjamin P, Benjamin Espinasse, Curtis J Richardson, Cole W Matson, Gregory V Lowry, Dana E Hunt, Mark R Wiesner, Emily S Bernhardt, et al. (2014). Emerging contaminant or an old toxin in disguise? Silver nanoparticle impacts on ecosystems. Environ Sci Technol, 48(9). pp. 5229–5236. 10.1021/es405454v Retrieved from https://hdl.handle.net/10161/15708.

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Curtis J. Richardson

Research Professor of Resource Ecology in the Division of Environmental Science and Policy

Curtis J. Richardson is Professor of Resource Ecology and founding Director of the Duke University Wetland Center in the Nicholas School of the Environment. Dr. Richardson earned his degrees from the State University of New York and the University of Tennessee.

His research interests in applied ecology focus on long-term ecosystem response to large-scale perturbations such as climate change, toxic materials, trace metals, flooding, or nutrient additions. He has specific interests in phosphorus nutrient dynamics in wetlands and the effects of environmental stress on plant communities and ecosystem functions and services. The objectives of his research are to utilize ecological principles to develop new approaches to environmental problem solving. The goal of his research is to provide predictive models and approaches to aid in the management of ecosystems.

Recent research activities: 1) wetland restoration of plant communities and its effects on regional water quality and nutrient biogeochemical cycles, 2) the development of ecosystem metrics as indices of wetland restoration success, 3) the effects of nanomaterial on wetland and stream ecosystem processes, 4) the development of ecological thresholds along environmental gradients, 5) wetland development trends and restoration in coastal southeastern United States, 6) the development of an outdoor wetland and stream research and teaching laboratory on Duke Forest, 7) differential nutrient limitation (DNL) as a mechanism to overcome N or P limitations across trophic levels in wetland ecosystems, and 8) carbon sequestration in coastal North Carolina pocosins.

Richardson oversees the main analytical lab in NSOE, which is open to students and faculty. Dr. Richardson has been listed in Who's Who in Science™ annually since 1989 and was elected President of the Society of Wetland Scientists in 1987-88. He has served on many editorial review committees for peer-reviewed scientific journals, and he is a past Chair of the Nicholas School Division of Environmental Sciences and Policy. Dr. Richardson is a Fellow of the American Association for the Advancement of Science, the Society of Wetland Scientists, and the Soil Science Society of America.


Dana E. Hunt

Associate Professor of Microbial Ecology

My research focus is on understanding the ecology of microbes through examination of their genes and lifestyles. Bacteria are the most diverse organisms on earth and play a pivotal role in planetary cycling of nutrients and energy. Yet, we have a poor understanding of the factors that drive their diversity and dynamics in the environment. The lab's emphasis is on studying bacterial interactions with the environment at the appropriate temporal and spatial scale including the effect of temperature changes on bacterial populations and bacterial interactions with other organisms. Another area of active research is the response and adaptation of bacteria to emerging pollutants such as antibiotics and nanoparticles.


Mark Wiesner

James B. Duke Distinguished Professor of Civil and Environmental Engineering

Wiesner's research interests include membrane processes, nanostructured materials, transport and fate of nanomaterials in the environment, nano plastics, colloidal and interfacial processes, and environmental systems analysis.

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