Modeli W n a g te N r a sh n e o d sil Movderli ng Transfo for r

Transcription

1 Modeling Nanosilver Watershed Modeling Transforma;ons in for Nanosilver Risk Assessment Freshwater Sediments Amy Dale Engineering and Public Policy Elizabeth Casman, Ph.D. Engineering and Public Policy Gregory Lowry, Ph.D. Civil and Environmental Engineering Carnegie Mellon University Quarterly Review

2 Risk Assessment: Nanopar;cles Nanotechnology is a mulf- billion dollar industry NanoparFcles nm 2 Unique size- dependent properfes What are the implica0ons of 2? 2! Introduc6on [Previous Work] MoFvaFon ObjecFve Approach Conclusions

3 Nanosilver Nanosilver is the largest and fastest growing applicafon of nanotechnology in consumer goods 1 Broad- spectrum biocide High surface- to- volume rafo à rapid release of toxic Ag + Fate and transport models needed to assess risk Introduc6on [Previous Work] MoFvaFon ObjecFve Approach Conclusions 3!

4 Modeling Nanosilver Previous Transforma;ons in Work Freshwater Sediments A.L. Dale, G.V. Lowry, E.A. Casman. Modeling nanosilver transforma6ons in freshwater sediments. (submifed) 4!

5 Previous work! Mo;va;on Nanosilver is the largest and fastest growing applicafon of nanotechnology in consumer goods 1 Broad- spectrum biocide 2. Nanosilver aggregates with sediments. Sediment co- transport (advecfon, se]ling) and bed chemistry are key determinants of fate. High surface- to- volume rafo à rapid release of toxic Ag + Fate and transport models needed to assess risk [Previous Background Work: & Mo6va6on ObjecFve ObjecFve Methods Approach Results & Key Discussion Findings Conclusion ] Ag 0 Sed 5!

6 [Previous Work: MoFvaFon Objec6ve Approach Key Findings ] Previous work! Objec;ve Adapt a convenfonal metal- sediment chemistry model (Di Toro et al., 1996) to describe chemical transformafons of nanosilver in sediments Di Toro, D. M.; Mahony, J. D.; Hansen, D. J.; Berry, W. J., A model of the oxidafon of iron and cadmium sulfide in sediments. Environmental Toxicology and Chemistry 1996, 15, (12), !

7 [Previous Background Work: & Mo6va6on MoFvaFon ObjecFve ObjecFve Methods Approach Results & Key Discussion Findings Conclusion ] Previous work! Conceptual Model 7!

8 Previous work! Key Findings Conclusion 1: Non- toxic Ag 2 S dominates speciafon, while toxic Ag + is present only at low concentrafons (<0.01 wt- %) Conclusion 2: Environmental condifons and seasonal variafon are important! Eutrophic systems (e.g., low- lying lakes and wetlands) minimize toxic Ag + formafon The half- life of typical sulfidized (85% Ag 2 S) AgNPs in the sediment may vary from 5 years to over a century depending on redox condifons But this model can t tell us Predicted environmental concentrafons Strengths and weaknesses of alternafve risk management strategies 8! [Previous Work: MoFvaFon ObjecFve Approach Key Findings ]

9 Modeling Nanosilver Current Transforma;ons in Work Freshwater Sediments 9!

10 Mo;va;on Risk management and policy decisions owen require a broader perspec6ve 10! IntroducFon [Previous Work] Mo6va6on ObjecFve Approach Conclusions

11 IntroducFon [Previous Work] MoFvaFon Objec6ve Approach Conclusions Objec;ve Model nanosilver transport and chemical transformafons in a watershed basin, accounfng for stream loadings from point sources (WWTPs, CSOs) and non- point sources (agricultural runoff from land- applied biosolids) 11!

12 Modeling Nanosilver Approach Transforma;ons in Freshwater Sediments 12!

13 Conceptual Model Hydrological Model land control files point sources Land SimulaFon river control files non- point sources River SimulaFon Hydrology Annual varia0on in water quality cons0tuents (temp, ph, DO) Stream loadings from NPS, PS Contaminant Fate Model Phase 5 WSM Creates HSPF control files from a library of Fortran g77 scripts and ASCII files containing parameter definifons, parameter values, formanng instrucfons, geographic data, etc. HSPF HSPF control files Performs the operafons specified in the control files for all land and river segments in the basin IntroducFon [Previous Work] MoFvaFon ObjecFve Approach Conclusions

14 IntroducFon [Previous Work] MoFvaFon ObjecFve Approach Conclusions What does this get us? Bounds on the predicted environmental concentrafons of AgNPs and reacfon byproducts Do we exceed water quality standards or toxicity thresholds? What are the expected loadings to the estuary? Understanding of the relafve impact of point and non- point sources on river and bed concentrafons Comparison of alternafve land use best management pracfces on the reducfon of stream loadings How does land type (e.g., degree of urbanizafon) affect loadings? Understanding of where AgNPs accumulate and the impact of transient bed storage on fate Framework generalizable to other metal and metal oxide NPs (CuO, ZnO) Ability to include biouptake and ecotox submodels in the future 17!

15 IntroducFon [Previous Work] MoFvaFon ObjecFve Approach Conclusions What does this get us? Bounds on the predicted environmental concentrafons of AgNPs and reacfon byproducts Do we exceed water quality standards or toxicity thresholds? What are the expected loadings to the estuary? Understanding of the relafve impact of point and non- point sources on river and bed concentrafons Comparison of alternafve land use best management pracfces on the reducfon of stream loadings How does land type (e.g., degree of urbanizafon) affect loadings? Understanding of where AgNPs accumulate and the impact of transient bed storage on fate Framework generalizable to other metal and metal oxide NPs (CuO, ZnO) Ability to include biouptake and ecotox submodels in the future 17!

16 IntroducFon [Previous Work] MoFvaFon ObjecFve Approach Conclusions What does this get us? Bounds on the predicted environmental concentrafons of AgNPs and reacfon byproducts Do we exceed water quality standards or toxicity thresholds? What are the expected loadings to the estuary? Understanding of the relafve impact of point and non- point sources on river and bed concentrafons Comparison of alternafve land use best management pracfces on the reducfon of stream loadings How does land type (e.g., degree of urbanizafon) affect loadings? Understanding of where AgNPs accumulate and the impact of transient bed storage on fate Framework generalizable to other metal and metal oxide NPs (CuO, ZnO) Ability to include biouptake and ecotox submodels in the future 17!

17 IntroducFon [Previous Work] MoFvaFon ObjecFve Approach Conclusions What does this get us? Bounds on the predicted environmental concentrafons of AgNPs and reacfon byproducts Do we exceed water quality standards or toxicity thresholds? What are the expected loadings to the estuary? Understanding of the relafve impact of point and non- point sources on river and bed concentrafons Comparison of alternafve land use best management pracfces on the reducfon of stream loadings How does land type (e.g., degree of urbanizafon) affect loadings? Understanding of where AgNPs accumulate and the impact of transient bed storage on fate Framework generalizable to other metal and metal oxide NPs (CuO, ZnO) Ability to include biouptake and ecotox submodels in the future 17!

18 IntroducFon [Previous Work] MoFvaFon ObjecFve Approach Conclusions What does this get us? Bounds on the predicted environmental concentrafons of AgNPs and reacfon byproducts Do we exceed water quality standards or toxicity thresholds? What are the expected loadings to the estuary? Understanding of the relafve impact of point and non- point sources on river and bed concentrafons Comparison of alternafve land use best management pracfces on the reducfon of stream loadings How does land type (e.g., degree of urbanizafon) affect loadings? Understanding of where AgNPs accumulate and the impact of transient bed storage on fate Framework generalizable to other metal and metal oxide NPs (CuO, ZnO) Ability to include biouptake and ecotox submodels in the future 17!

19 Modeling Nanosilver Transforma;ons Thank You in Freshwater Sediments Acknowledgements CBPO Modeling Team NSF NEEP IGERT Fellowship ARCS Scholarship 2013 Anchor QEA Scholarship

20 References 1. Analysis of Consumer Products, Nanotechnology Project; Project on Emerging Nanotechnologies, Woodrow Wilson InternaFonal Center for Scholars, 2012; Mueller, N. C.; Nowack, B., Exposure modeling of engineered nanoparfcles in the environment. Environ Sci Technol 2008, 42, (12), Go]schalk, F.; Sonderer, T.; Scholz, R. W.; Nowack, B., Modeled environmental concentrafons of engineered nanomaterials (TiO2, ZnO, Ag, CNT, fullerenes) for different regions. Environ Sci Technol 2009, 43, (24), Kaegi, R.; Voegelin, A.; Sinnet, B.; Zuleeg, S.; Hagendorfer, H.; Burkhardt, M.; Siegrist, H., Behavior of metallic silver nanoparfcles in a pilot wastewater treatment plant. Environ Sci Technol 2011, 45, (9), !