2012 Progress Report: Transatlantic Initiative for Nanotechnology and the Environment

EPA Grant Number: R834574
Title: Transatlantic Initiative for Nanotechnology and the Environment
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: August 1, 2011 through July 31,2012
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: (1) 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; (2) 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; (3) validate models with information generated from experiments designed to address 1 for MNMs introduced through a pilot scale Waste Water Treatment Process (WWTP) to key terrestrial ecoreceptors, including effects of MNMs on the WWTP itself; (4) determine realistic MNM emission scenarios for Tier 1 MNMs in wastewater from the WWT pilot plant data and develop first generation Life-Cycle-Analysisinspired 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 1, 2, and 3; and (5) 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)

In particular, we have investigated the mechanisms of ZnO NP undergoing transformations in the presence of sulphide and phosphate, respectively. We have measured the solubility of the resulting ZnS and Zn-phosphate phases as a function of the degree of sulfidation and inorganic phosphorylation. Finally, we have measured transformation of ZnO in the presence of phosphate and sulphide with varing S/P ratios. The evidence suggests that fully and partially sulfidized and phosphated Ag and ZnO NPs can form depending on the S/P/Zn/Ag ratios, with strong evidence that core-shell structures are important at low to intermediate concentrations of S and/or phosphate. Method development and application of AF4- multidetection for in situ detection and characterization of Ag MNMs and aged Ag MNMs in soil has been completed. A method was developed that allowed for isolation and characterization of Ag MNMs in soil and biosolids amended soil.

Bioavailability and toxicity of Ag, Au, and ZnO NPs and selected transformed (weathered) NPs (UKY): Studies have examined the bioavailability and effects of both pristine and “aged” Ag, ZnO, and Au NPs to a variety of ecoreceptors. Pristine Ag-NPs have been demonstrated to be more toxic to C. elegans than aged Ag-NPs (fully sulfidized) with the LC50 values for the sulfidized, pristine Ag-NPs, and Ag+ of >10,000 μg/L, 1,750 μg/L and 25 μg/L, respectively, in the presence of food. In the absence of food, the LC50 values were >3,000 μg/L, 50 μg/L, and 2.5 μg/L, respectively. The distribution of Ag in exposed nematodes as determined by synchrotron X-ray fluorescence microscopy indicate that the higher toxicity of the pristine versus aged Ag-NPs is due to their greater Ag bioavailability. Reproduction was the most sensitive endpoint for each of the Ag treatments with EC50 of 4,000 μg/L, 500 μg/L, and 15 μg/L for the aged, pristine Ag-NPs, and for Ag+, respectively. Methods for measuring total concentration of Ag ions released during exposure to both the pristine and sulfidized Ag-NPs have been optimized and the observed toxicity cannot be explained solely by the concentration of Ag+ after 24 h of exposure, suggesting particle-specific effects. Short-term molecular level effects, including changes in gene expression of nine stress-response genes, catalase activity, and in levels of biomarkers of oxidative stress - protein carbonyls, have been investigated in Eisenia fetida exposed to soil containing PVP Ag-NPs (small and large size) and Ag ions. The molecular-level changes in the earthworms exposed to both particle and ionic Ag forms and significant correlations of decreased gene expression with increased Ag soil concentration observed for two of the genes (CAT and HSP70) suggest that these responses were determined by Ag soil concentration, independent of the NP size and whether the worms were exposed to ions or particles. Given that <15% of Ag in the NPs was oxidized in these soils, our results suggest that dissolution of Ag-NPs likely occurs after or during their uptake of intact or aged Ag NPs.

Bioavailability/toxicity studies of nanoparticles in invertebrates (CEH):

Studies on the effects of varying soil pH and soil porewater chemistry on the effects of ZnO MNMs and ionic Zn on Eisenia fetida, are progressing well. Bioavailability and toxicity studies of nanoparticles initially intended to be undertaken in soil porewater has been moved to full scale soil exposures. Overall, the toxicity of ZnO MNM-spiked soils is lower than that of ionic Zn spiked soils. We have developed an initial conceptual model from these results, whereby toxicity of ZnO MNMs occurs either by (i) dissolution in the soil and uptake in ionic form; (ii) uptake of MNMs followed by dissolution in the tissues, or a linear combination of the two phenomena.

Bioavailability/toxicity studies of nanoparticles in bacteria (Roth): PhosphoLipid Fatty Acid analyses of bacterial cultures of Pseudomonas putida and P. fluorescens with 100 μM Zn2+ or ZnO nanoparticles revealed differences in membrane lipid composition compared to the control. However, no significant differences were observed between ZnO nanoparticles and Zn2+ ions. Silver supplied either as Ag+ ions or Ag nanoparticles was toxic to both P. putida and P. fluorescens.

Growth was negatively affected by 5 μg ionic Ag+/L, and completely inhibited above approx. 20 μg ionic Ag+/L. Ag nanoparticles completely inhibited growth above 0.5 and 1 mg Ag/L in P.putida and P. fluorescens, respectively. Dissolved Ag+ comprised up to 10% of Ag nanoparticles in solution, indicating that toxicity of nanoparticles was likely due to dissolved Ag+. Preliminary experiments with TiO2 nanoparticles appeared to show that growth of P. putida was not affected up to at least 1 g/L. However, quantitative data could not be obtained as TiO2 obscured the determination of bacterial growth via photometric and fluorometric methods and bacterial protein assays.

Production of bespoke MNP and metal salts enriched sewage sludges at the pilot plant(Cranfield):

The anaerobically-treated Control, Nanoparticle and Bulk metal sewage sludge was produced and delivered to Rothamsted in June 2012. Findings during the production process include: (1) The majority of the dosed materials, either dissolved or nanoparticulate, is associated with the solid components of wastewater. (2) Accumulation of nanomaterials in the treatment works delivers them to terrestrial ecosystems. (3) Some evidence exists for damage to bacterial cells and microbial abundance within the activated sludge process, but stimulation also takes place – either by lightly stressing the biota or providing extra oxygen. (4) Overall, the treatment systems studied are resilient to the increased dosages of both dissolved and nanoparticulate metals, and no significant differentiation exists between the two.

Preparation of soil-sludge mixtures (Roth): The sludges were dried, ground and metal content analyzed. The proposal was put forward that because of the limited amount of sludge, the tests with sludge would be performed on one soil (from the United Kingdom (UK)) instead of two (from the UK and the United States). In discussion, it was clear that the properties of the UK and US soil were similar and that there was little scientific benefit in including two soils. This was agreed by all. Soil was collected, mixed with the sludges and recently made available for distribution to all contractors in the United States and UK. Soil was mixed with sludge to a final concentration of 1,400 ppm Zn in the Bulk metal mixture, concurrent with the US EPA limit for soils.

Bioavailability/toxicity studies in plants (Triticum aestivum) (Roth): Initial wheat growth studies in the soil-sludge mixtures were not successful. Plants died after a few weeks in all mixtures (control, nanoparticle and bulk metal). Growth was unaffected in soil to which no sewage sludge was added. Toxicity appeared to be caused by high ammonium concentrations (up to 0.8 mg NH4-N g-1 soil) as determined from soil extracts and soil electrical conductivity. Growth trials in soil-sludge mixtures with further soil dilutions, dilutions with inert quartz, at different water contents and in autoclaved soil, are currently underway.

To develop a technique based on DGT (diffusive gradients in thin-films) for in situ measurements of MNMs in the environment, (Lancaster Uni): (1) Evaluating retention of ZnO and Ag NPs by the diffusive hydrogel layer used in the DGT technique; (2) Investigating uptake kinetics of ZnO and Ag NPs for the binding layer of the DGT device; (3) Modifying the DGT diffusive layer by adding a dialysis membrane. Performance tests of the modified DGT devices in mixed solutions with known concentrations of ZnO and Ag NPs and their ionic forms; (4) Measuring diffusion coefficient of ZnO NP, Ag NP, Zn2+ and Ag+ in the diffusive gel and dialysis membrane; (5) Evaluating binding mechanisms of ZnO NP to two different types of the DGT binding resins using infrared spectroscopy and making comparisons with the binding behaviour of Zn2+.

Emerging findings: The binding material in the DGT devices (either Chelex or Metsorb) can bind ZnO and Ag NPs with fast uptake kinetics and a high capacity. ZnO and Ag NPs can diffuse through the standard diffusive gel of a DGT device, but not through 1,000 MWCO dialysis membrane. Ionic forms of Zn and Ag can diffuse through both materials. The concentration of labile nanoparticles can be measured quantitatively using a combination of two DGT devices: standard DGT and dialysis DGTdetailed analysis of infrared spectroscopic measurements of Chelex and Metsorb exposed to Zn2+, ZnO NP, or a mixture of both, showed distinctive patterns for the different bound species. Using standard DGT with IR spectroscopic analysis of the binding material, concentrations of different Zn species could be obtained.

Risk Assessment Modeling: In a coordinated effort between CMU and Duke, we are developing a mathematical framework for modeling nanomaterials in the environment capable of handling nanoparticle transformations, aggregation, and chemistry, reflecting current scientific understanding. CMU is heading up the aquatic sediment modeling, Duke is handling watershed modelling and particle aggregation modeling in the water column. The CMU sediment model has been calibrated to CEINT nanoAg mesocosm data. Preliminary runs of this model have indicated that release of silver ion (the most toxic silver species) from the sediments into the water column has seasonal variability, with more silver being released during the summer months. Sediments of oligotrophic systems release more silver ion than sediments of eutrophic systems. The work on sulfidation of ZnO NPs has resulted in a manuscript currently in review in Environmental Science & Technology. Another manuscript on ZnO NP transformations in the presence of phosphate is currently in preparation and will be submitted by mid December. We found that surface coating had a profound effect on partitioning of Ag MNMs to pore water when biosolids were not present but had no effect when biosolids were present. Over the short term (up to two months), the presence of biosolids either increased or had no effect on pore water Ag concentrations, but after 6 months, biosolids amended soils had greatly reduced pore water Ag concentrations. Despite extensive sulfidation of Ag MNMs in sewage sludge amended soils, there was an increase in the proportion of dissolved Ag in pore water over 6 months. A manuscript on this work is currently in preparation.


Journal Articles on this Report : 10 Displayed | Download in RIS Format

Other project views: All 68 publications 38 publications in selected types All 38 journal articles
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Journal Article Handy RD, Cornelis G, Fernandes T, Tsyusko O, Decho A, Sabo-Attwood T, Metcalffe C, Steevens JA, Klaine SJ, Koelmans AA, Horne N. Ecotoxicity test methods for engineered nanomaterials: practical experiences and recommendations from the bench. Environmental Toxicology and Chemistry 2012;31(1):15-31.
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R834574 (2012)
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  • Journal Article Judy JD, Unrine JM, Rao W, Wirick S, Bertsch PM. Bioavailability of gold nanomaterials to plants: importance of particle size and surface coating. Environmental Science & Technology 2012;46(15):8467-8474.
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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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  • Journal Article Lombi E, Nowack B, Baun A, McGrath SP. Evidence for effects of manufactured nanomaterials on crops is inconclusive. Proceedings of the National Academy of Sciences of the United States of America 2012;109(49):E3336.
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  • Journal Article Lowry GV, Espinasse BP, Badireddy AR, Richardson CJ, Reinsch BC, Bryant LD, Bone AJ, Deonarine A, Chae S, Therezien M, Colman BP, Hsu-Kim H, Bernhardt ES, Matson CW, Wiesner MR. Long-term transformation and fate of manufactured Ag nanoparticles in a simulated large scale freshwater emergent wetland. Environmental Science & Technology 2012;46(13):7027-7036.
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  • Journal Article Money ES, Reckhow KH, Wiesner MR. The use of Bayesian networks for nanoparticle risk forecasting: model formulation and baseline evaluation. Science of the Total Environment 2012;426:436-445.
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  • Journal Article Neal AL, Kabengi N, Grider A, Bertsch PM. Can the soil bacterium Cupriavidus necator sense ZnO nanomaterials and aqueous Zn2+ differentially? Nanotoxicology 2012;6(4):371-380.
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  • Journal Article Tsyusko OV, Unrine JM, Spurgeon D, Blalock E, Starnes D, Tseng M, Joice G, Bertsch PM. Toxicogenomic responses of the model organism Caenorhabditis elegans to gold nanoparticles. Environmental Science & Technology 2012;46(7):4115-4124.
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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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  • Journal Article von der Kammer F, Ferguson PL, Holden PA, Masion A, Rogers KR, Klaine SJ, Koelmans AA, Horne N, Unrine JM. Analysis of engineered nanomaterials in complex matrices (environment and biota): general considerations and conceptual case studies. Environmental Toxicology and Chemistry 2012;31(1):32-49.
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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:

    CEINT Adds New International Nano-Safety Initiative Exit

    Progress and Final Reports:

    Original Abstract
  • 2011 Progress Report
  • 2013 Progress Report
  • 2014 Progress Report
  • 2015 Progress Report
  • Final Report