Low concentrations of silver nanoparticles in biosolids cause adverse ecosystem responses under realistic field scenario.


A large fraction of engineered nanomaterials in consumer and commercial products will reach natural ecosystems. To date, research on the biological impacts of environmental nanomaterial exposures has largely focused on high-concentration exposures in mechanistic lab studies with single strains of model organisms. These results are difficult to extrapolate to ecosystems, where exposures will likely be at low-concentrations and which are inhabited by a diversity of organisms. Here we show adverse responses of plants and microorganisms in a replicated long-term terrestrial mesocosm field experiment following a single low dose of silver nanoparticles (0.14 mg Ag kg(-1) soil) applied via a likely route of exposure, sewage biosolid application. While total aboveground plant biomass did not differ between treatments receiving biosolids, one plant species, Microstegium vimeneum, had 32 % less biomass in the Slurry+AgNP treatment relative to the Slurry only treatment. Microorganisms were also affected by AgNP treatment, which gave a significantly different community composition of bacteria in the Slurry+AgNPs as opposed to the Slurry treatment one day after addition as analyzed by T-RFLP analysis of 16S-rRNA genes. After eight days, N2O flux was 4.5 fold higher in the Slurry+AgNPs treatment than the Slurry treatment. After fifty days, community composition and N2O flux of the Slurry+AgNPs treatment converged with the Slurry. However, the soil microbial extracellular enzymes leucine amino peptidase and phosphatase had 52 and 27% lower activities, respectively, while microbial biomass was 35% lower than the Slurry. We also show that the magnitude of these responses was in all cases as large as or larger than the positive control, AgNO3, added at 4-fold the Ag concentration of the silver nanoparticles.





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Publication Info

Colman, Benjamin P, Christina L Arnaout, Sarah Anciaux, Claudia K Gunsch, Michael F Hochella, Bojeong Kim, Gregory V Lowry, Bonnie M McGill, et al. (2013). Low concentrations of silver nanoparticles in biosolids cause adverse ecosystem responses under realistic field scenario. PLoS One, 8(2). p. e57189. 10.1371/journal.pone.0057189 Retrieved from https://hdl.handle.net/10161/15714.

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Claudia K. Gunsch

Professor in the Department of Civil and Environmental Engineering

Claudia Gunsch is a Professor of Civil and Environmental Engineering and holds secondary appointments in the Nicholas School of the Environment and the Department of Biomedical Engineering. She joined the Duke Faculty in 2004 after obtaining her PhD from the University of Texas at Austin, her MS from Clemson University and her BS from Purdue University. Currently, she serves as the Director for PreMiEr, the National Science Foundation Engineering Research Center for Precision Microbiome Engineering which is a joint venture between Duke University, North Carolina A&T State University, North Carolina State University, the University of North Carolina – Chapel Hill and the University of North Carolina – Charlotte. She also serves as an Associate Director for the Duke Microbiome Center. Previous leadership roles include serving as Associate Dean for Research and Infrastructure for the Pratt School of Engineering (2021-2022), Associate Vice Provost for Faculty Advancement (2019-2021) and as the Director of IBIEM (Integrative Bioinformatics for Investigating and Engineering Microbiomes), a joint graduate training program between Duke and North Carolina A&T State University (2015-2021).

Dr. Gunsch’s research bridges environmental engineering and molecular biotechnology. Current research foci include investigating the ecological impacts of emerging contaminants on environmental microbiomes, developing microbiome engineering approaches for bioremediation, studying microbial evolution following exposure to anthropogenic contaminants and developing innovative water treatment technologies. Her work has been funded in excess of $36 million by the National Science Foundation, US Environmental Protection Agency, National Institute for Environmental Health and Safety as well as state funding agencies and private industry.  Since becoming a faculty member, she has served as the primary mentor for 28 graduate students (8 MS and 20 PhD), 34 undergraduate students and 8 postdoctoral associates. She has been recognized for her research, teaching and service activities with several awards including the 2009 National Science Foundation Faculty Early Career Development Award, 2013 Langford Lectureship Award, 2016 Capers and Marion McDonald Award for Excellence in Mentoring and Advising and the 2016 American Society of Civil Engineers (ASCE) Walter L. Huber Civil Engineering Research Prize. Dr. Gunsch was also named ASCE Environmental & Water Resources Institute Fellow in 2022, Bass Fellow in 2016 and Fellow of the National Academy of Engineering for the United States Frontiers of Engineering in 2011 as well as the Indo-American Frontiers of Engineering in 2014.

She currently serves as Editor in Chief for Biodegradation. She is also a member of the Editorial Board for npj Clean Water and Industrial Biotechnology.  She serves on the Association of Environmental Engineering and Science Professors (AEESP) Board of Directors and has previously held several leadership roles within the Environmental & Water Resources Institute (EWRI).  Most recently, she served as the Environmental Council representative to the Technical Executive Committee to EWRI. 


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.


Justin Prouty Wright

Professor of Biology

My research focuses on understanding the causes and consequences of patterns of biological diversity across the planet. I am particularly interested in two broad questions: 1)How does the modification of the environment by organisms affect community structure and ecosystem function? and 2) what aspects of biodiversity matter most in the regulation of ecosystem function? While much of my research has focused on wetland plant communities, I am willing to study any organism and work in any ecosystem to answer the questions that interest me. I have worked in systems ranging from tropical streams to desert shrublands. My research program combines observational and experimental approaches with modeling to develop and test hypotheses and build towards synthetic ecological theory.


Emily S. Bernhardt

James B. Duke Distinguished Professor

Emily Bernhardt is an ecosystem ecologist and biogeochemist whose research is principally concerned with tracking the movement of elements through ecological systems. Dr. Bernhardt's research aims to document the extent to which the structure and function of aquatic ecosystems is being altered by land use change (urbanization, agriculture, mining) global change (rising CO2, rising sea levels) and chemical pollution. Ultimately this information is necessary to determine whether and how ecosystem change can be mitigated or prevented through active ecosystem management.

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