2013 Progress Report: Transatlantic Initiative for Nanotechnology and the Environment

EPA Grant Number: R834574
Title: Transatlantic Initiative for Nanotechnology and the Environment
Investigators: Unrine, Jason M. , Bertsch, Paul M. , Wiesner, Mark R. , Lowry, Gregory V. , Tsyusko, Olga V. , Casman, Elizabeth , Liu, Jie , Kabengi, Nadine
Current Investigators: Bertsch, Paul M. , Dorey, Robert A , Rocks, Sophie A , McNear, David H. , Unrine, Jason M. , Wiesner, Mark R. , Lowry, Gregory V. , Tsyusko, Olga V. , Neal, Andy , Jefferson, Bruce , Svendsen, Claus , Spurgeon, David , Casman, Elizabeth , Zhang, Hao , Harris, J. , Liu, Jie , Ritz, Karl , Kabengi, Nadine , McGrath, Steve , Lofts, Steve
Institution: University of Kentucky , Carnegie Mellon University , Lancaster University , Cranfield University , Centre for Ecology and Hydrology , Duke University , Rothamsted Research
Current Institution: University of Kentucky , Carnegie Mellon University , Centre for Ecology and Hydrology , Cranfield University , Duke University , Lancaster University , Rothamsted Research
EPA Project Officer: Klieforth, Barbara I
Project Period: August 1, 2010 through September 30, 2014 (Extended to June 30, 2016)
Project Period Covered by this Report: September 30, 2012 through October 1,2013
Project Amount: $2,000,000
RFA: Environmental Behavior, Bioavailability and Effects of Manufactured Nanomaterials - Joint US – UK Research Program (2009) RFA Text |  Recipients Lists
Research Category: Chemical Safety for Sustainability

Objective:

We have developed a life cycle perspective inspired conceptual model (CM) that suggests the importance of terrestrial ecosystems as a major repository of ZnO, TiO2, and Ag manufactured nanomaterials (MNMs) introduced via the land application of MNM-containing biosolids. In this project we are investigating the transport, fate, behavior, bioavailability, and effects of MNMs in(to) agroecosystems under environmentally realistic scenarios organized around three key hypotheses: Hypothesis (H1) Surface chemistry is the primary factor influencing the fate and transport of MNMs in the terrestrial environment as well as the bioavailability and effects to biological receptors; Hypothesis (H2) Once released to the environment, pristine MNM surfaces will be modified by interactions with organic and inorganic ligands (macromolecules) or via other biogeochemical transformations (aging effects forming a-MNMs); Hypothesis (H3) Ecoreceptors will respond to interactions with pristine metal and metal oxide MNMs, a-MNMs, and/or dissolved constituent metal ions and bulk oxides by specific ecological and toxicogenomic responses that will reflect their combined effects. The overall objectives are to: O1) compare the transport, fate, behavior, bioavailability, and effects of MNMs, a-MNMs, and/or dissolved free metals/bulk oxides to organisms with key terrestrial ecosystem functions, as well as exposure pathways involving humans; O2) determine MNM, surface modified MNM and a-MNM interactions with important biological targets relevant to the BLM and pBRM models and relate these interactions to physicochemical properties; O3) validate models with information generated from experiments designed to address O1 for MNMs introduced through a pilot scale Waste Water Treatment Process (WWTP) to key terrestrial ecoreceptors, including effects of MNMs on the WWTP itself; O4) determine realistic MNM emission scenarios for Tier 1 MNMs in wastewater from the WWT pilot plant data and develop first generation Life-Cycle-Analysis-inspired Risk Assessment (LCA-RA) model components for terrestrial effects of Tier 1 MNMs and a-MNMS based on data generated in experiments designed to address O1, O2, & O3; and O5) provide tools for in situ detection, monitoring, and characterization of pristine MNMs and a-MNMs in environmental media and biota.

Progress Summary:

Aging and transformations of ZnO and Ag NPs in a simulated wastewater treatment process, soil, and in biosolid amended soil (CMU, UKY): During this reporting period, we completed the characterization of wastewater treatment sewage sludge biosolids generated by our UK partners at Cranfield University. In brief, we found that no intact Ag or ZnO makes its way through the pilot wastewater treatment plant. The biosolids contained 100% Ag2S and for Zn, it was found that the speciation was likely a mixture of Zn3(PO4)2, ZnS, and Zn bound to Fe oxohydroxides. There were few differences in the molecular speciation of Zn and Ag in bulk ZnO/AgNO3 biosolids versus nanometal biosolids (Ma et al., in press). On the other hand, a smaller scale study conducted by spiking biosolids from a Lexington, KY WWTP demonstrated that some of the Ag2S present in the MNM treated biosolids existed as nanoparticles that were mobile in the pore water of soil treated with those biosolids (Whitley et al., 2013). Initial results of outdoor lysimeter leaching studies from our UK partners at Rothamsted revealed that Ag from the MNM treated WWTP were leached at twice the rate as the AgNO3 biosolids. Whitley et al., (2013) demonstrated that initial coating has no effect on the final speciation and behavior of Ag MNMs once they have come into contact with sewage sludge.

Bioavailability and toxicity of Ag and ZnO NPs and selected transformed (weathered) MNMs: Ongoing studies of pristine and aged (fully suflidized) Ag NPs in C. elegans are nearly completed. The results indicated that there are particle specific effects and that the relative importance of Ag ions as a contributor to toxicity decreases with increasing Ag concentration. The results of imaging and toxicogenomic studies suggested that toxicity of pristine and aged Ag NPs differs from each other and from Ag ions. The mechanism of fully sulfidized Ag NP toxicity is likely related to damage to the cuticle. Studies of the toxicity of pristine ZnO, fully phosphatized ZnO, and Zn3(PO4)2 shell-ZnO core aged NPs have been initiated in both C. elegans and Medicago truncatula inoculated with Sinorhizobium meliloti. Our partners at Rothamstead and CEH in the UK are completing similar studies in E. fetida, C. elegans and P. fluorescens.

Bioavailability and toxicity of transformed TiO2, Ag and ZnO NPs in biosolids amended soils: We have also completed exposures of Medicago truncatula inoculated with Sinorhizobium meliloti to both fresh biosolids amended soil and biosolids amended soil that was aged at Rothamsted research for 6 months. Samples have been collected to determine metal uptake, gene expression, nodulation and nitrogen fixation rates, and soil microbial community responses. The data are currently being analyzed from these studies. Similar studies have been completed in Triticum aestivum at Rothamsted and are underway in E. fetida at CEH. Cranfield is also completing microbial community analyses in the fresh and aged biosolids amended soils. The results are just beginning to pour in from these studies and will be reported in the next reporting period.

Risk Assessment Modeling: We have developed a one-dimensional mass balance model of the sulfide- and oxygen-dependent chemical transformations of AgNPs in sediments. Initial work on the sediment model was completed and published this year (Dale et al., 2013). The sediment model focused on the seasonally variable transformations that AgNPs and their reaction products will undergo in natural soils and sediments (e.g., sulfidation, oxidation, partitioning of Ag+ to organic carbon) under a range of environmental conditions, and the effect these transformations have on nanoparticle accumulation and bioavailability. Results show that the relative abundance of the toxic species Ag+ is extremely low (< 0.01 wt-%), and that environmental conditions play an important role in AgNP fate. The half-life of sulfidized AgNPs can vary from 6.6 years to over a century depending on oxygen availability in the sediments.

We have begun work on a watershed scale model whose backbone is a hybrid of HSPF and WASP7 (EPA models). This model will be able to represent a variety of agricultural practices and will have capabilities necessary to track Ag NP sources, sinks, and transformations in the environment. A collaboration with the EPA Chesapeake Bay Program has been instituted, and the first demonstration of this model will involve portions of the EPA Chesapeake Bay Program Phase 5 Watershed Model.
 
We have made significant progress conceptualizing a modified terrestrial biotic ligand model (tBLM) that will enable us to partition the bioavailability toxicity due to ions versus aged MNMs as a first iteration of our proposed pBRM model. This work is mainly being conducted by CEH. Unrine attended a workshop at CEH in Wallingford in September to learn how the U.S. team could best design experiments that help to parameterize this model with Lofts, Svendsen and Spurgeon.
 

Future Activities:

Several tasks still need to be accomplished for this project. In the coming year, we will complete data analysis for the phytotoxicity and microbial community studies in biosolids amended soil, complete hydroponic phytotoxicity studies with pristine and aged MNMs, and evaluate the potential for leaching and runoff of MNMs from biosolids amended soils. We will also conduct microbial toxicity studies with rhizobacteria. All of the toxicogenomic data from these experiments will need to be analyzed and a meta-analysis will need to be conducted to identify common toxicity pathways. Finally the role of the identified pathways will need to be probed using mutant strains and RNAi experiments.
 
We also plan to link models that describe the rates of transformation of MNMs during the wastewater treatment process to a land application exposure model and a stream and sediment transport and transformation model. These models will describe the fate and exposure rates for MNMs that enter wastewater streams. The second component has been to parameterize a pBRM model.


Journal Articles on this Report : 4 Displayed | Download in RIS Format

Other project views: All 68 publications 38 publications in selected types All 38 journal articles
Type Citation Project Document Sources
Journal Article Dale AL, Lowry GV, Casman EA. Modeling nanosilver transformations in freshwater sediments. Environmental Science & Technology 2013;47(22):12920-12928.
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R834574 (2013)
R834574 (2014)
R834574 (Final)
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  • Journal Article Judy JD, Unrine JM, Rao W, Bertsch PM. Bioaccumulation of gold nanomaterials by Manduca sexta through dietary uptake of surface contaminated plant tissue. Environmental Science & Technology 2012;46(22):12672-12678.
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    R834574 (2012)
    R834574 (2013)
    R834574 (Final)
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  • Journal Article Tsyusko OV, Hardas SS, Shoults-Wilson WA, Starnes CP, Joice G, Butterfield DA, Unrine JM. Short-term molecular-level effects of silver nanoparticle exposure on the earthworm, Eisenia fetida. Environmental Pollution 2012;171:249-255.
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    R834574 (2012)
    R834574 (2013)
    R834574 (Final)
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  • Journal Article Whitley AR, Levard C, Oostveen E, Bertsch PM, Matocha CJ, von der Kammer F, Unrine JM. Behavior of Ag nanoparticles in soil: effects of particle surface coating, aging and sewage sludge amendment. Environmental Pollution 2013;182:141-149.
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    R834574 (2013)
    R834574 (Final)
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  • Supplemental Keywords:

    Environmental nanotechnology, nanotoxicology, environmental chemistry, ecological and human health risks of manufactured nanomaterials, chemical speciation, biosensors, environmental chemistry, biogeochemistry

    Relevant Websites:

    http://www.research.uky.edu/odyssey/features/nanotech.html

    http://www.pratt.duke.edu/duke_ceint_tine

    http://www.rothamsted.ac.uk/ProjectDetails.php?ID=5094

    http://www.cranfield.ac.uk

    Progress and Final Reports:

    Original Abstract
  • 2011 Progress Report
  • 2012 Progress Report
  • 2014 Progress Report
  • 2015 Progress Report
  • Final Report