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Nanoparticles in the Environment
• W. Ball: Very (!) brief introduction to Engineered Nanoparticles (ENPs)
• W. Ball presentation of M. Wiesner* slides on“Nanoparticle Behavior in Complex Environments”
* Center for the Environmental Implications of NanoTechnology(CEINT)
Woodrow Wilson International Center for Scholars http://www.nanotechproject.org/
Thousands of manufacturer‐identified nanotechnology‐based consumer products currently on the market
Single Walled Carbon Nanotube (SWCNT)
Multi Walled Carbon Nanotubes
(MWCNT)•Mechanical Strength• Electrical Conductivity• High Aspect Ratio
Materials Properties
Carbon NanotubesInorganic ENPsEngineered Nanoparticles
Rational development of “safe‐by‐design” nanomaterials will require knowledge of how intrinsic nanoparticles properties (size, shape, surface chemistry) impact environmentally relevant properties (colloidal stability, sorption properties)
Naphthalene
Zn2+ (aq)
Oxidized Carbon Nanotube
Atomic Percentage of Surface Oxides
Sorp
tion
cap
acit
ySurface Oxygen
Concentration (Atomic %)
Sorp
tion
Cap
acit
y
Cho et al., Langmuir,26:967 (2010)
Cho et al., Env. Sci. Technol.43: 2899 (2008)
E.g. Impact of Surface Chemistryon sorption properties of carbon nanotubes
Surface Oxidation
OH
Surfactant Adsorption Natural Organic Molecules
e.g., surface modificationof MWCNTs
Probing the Influence of Surface Chemistryon Engineered Nanoparticle Behavior, Fate
and Effects in Aquatic Environments
after Smith et al. Environ. Sci. 43: 819(2009).
Amy L. Dale †‡, Gregory V. Lowry ‡, and Elizabeth A. Casman *†
† Engineering and Public Policy, Carnegie Mellon University‡ Civil and Environmental Engineering, Carnegie Mellon UniversityEnviron. Sci. Technol., Article ASAP (2015)DOI: 10.1021/acs.est.5b01205
Stream Dynamics and Chemical Transformations Control the Environmental Fate of Silver and Zinc Oxide Nanoparticles in a Watershed-Scale Model
Some take home points:(WPB addition, based on summary comments from MRW)
• Nanoparticles (whether engineered [“ENPs”] or natural):can be taken up by plants and animals;
• NPs are subject to trophic transfer‐ in some cases with biomagnification, in some with dilution;
• Attachment efficiencies appear to be a promising way of predicting NP behavior.
• The toxicity issue is secondary.Most important ‐‐ growing awareness of:• Complexity of nanometric phases in their interactions with living systems; and• Potentially important roles of NPs in uptake of chemicals, nutrient cycling, transport of other species, etc.
Nanomaterial behavior in complex environments
Mark R. Wiesner
Director Center for the Environmental Implications of NanoTechnology
Duke University
RISK
Hazard
Nanoparticle Properties
Exposure
• Composition • Bandgap • Size…
• Production amounts • Ambient
Concentrations • Effective dose…
• Mortality • Development • Population • Nutrient cycling…
RISK
Hazard
Nanoparticle Properties
System Properties Social Properties
Exposure
• Product life cycles and value chains
• Product use behaviors
• ENM production magnitudes
• pH, NOM, Ionic strength, …
• Surfaces (biotic, mineral, organic…)
• Fluid flow, temperature…
• Composition • Bandgap • Size…
• Surface affinity • Surface charge/
potential (ζ-potential) • Aggregation rate • Hydrophobicity…
RISK
Hazard
Nanoparticle Properties
System Properties Social Properties
Functional Assays
Exposure
• Measurement in prescribed system
• Quantifies a meaningful process for exposure, hazard or both
Functional Assay Focus – Fate & Transport Example
• Precipitation • Bioproduction • Photosensitization
i = speciation
EXPOSURE HAZARD
RISK
• Adsorption • Settling • Aggregation • Deposition
NOM
pH
Proteins
Ionic Strength
• Sulfidation • Complexation
!!!!!" = ±!"!!!! − !!"#!"#$%&"'!! + !!"#$%&'"(!! + !!"#$%!"#$%&'"(!! + !!"#$%&'()!! + !!"#$%&!"#$!! !
Release Rate
Mass Available
Social & Engineered Properties
System Properties
• Mutagenicity • Carcinogenicity • Mortality
• Concentration • Speciation
Material Properties (Intrinsic)
Band Gap
Core Size
Composition
DLVO
Hydro- phobicity
Steric Effects
System Derived Material Phenomena
Effect of Particle Size and Shape on Reactivity
Figure 1. A) SEM and B) AFM images of unsulfidized AgNP arrays produced by NSL. C) AFM image of an AgNP array after a 2-d exposure to 10 µM Na2S. D) AgNP height distributions before (black) and after (red) the exposure.
Time (h)
0 2 4 6 8 10 12 14M
ed
ian
Heig
ht
(nm
)0
10
20
30
40
50
60
70
pH 6.5
Figure 3. AgNP dissolution in 1 mg/L NaOCl at pH 6.5. Error bars are standard deviations of triplicate samples.
Kent and Vikesland, Environ. Sci. Technol., 2012, 46 (13), pp 6977–6984
Sulfidation of Ag, ZnO, and CuO NPs
Ag
ZnO +HS-
+HS-
Ag2S
ZnS
CuO +HS-
CuxSy
Ma et al., 2013 ES&T 47 (6), pp 2527–2534; Levard et al., ES&T 2011 45 (12), 5260.
Ma et al., 2014 ES Nano
Mode of Uptake of Ag by Duckweed
Duckweed Landoltia punctata
AgNO3 AgNPs Ag2S-NPs
18 h
~60 h Dead
Stegemeier et al., ES&T (in preparation)
Sulfidation Decreases Toxicity
Zebrafish Killifish C. Elegans Duckweed
Levard, Hotze, et al., ES&T 2013, 47, 13440−13448
ZnO Fate in the Wastewater System? Primary clarifier
(180 L)
Anaerobic digester (150 L)
\Secondary clarifier (150 L)
Zn2+
Control
ZnO NP
Mesocosms: Controlled Release Field Sites
! 30 mesocosms
! year-long experiments
! pulse & chronic inputs ! Nano- Ag, CeO2, Cu, Au, TiO2, SWCNTs
! NPs+conventional contaminants
! Release form commercial productions
Mesocosm Results
NSF EF-0830093
0%
20%
40%
60%
80%
100%
Mortality (+/-‐ SEM
)
Mesocosm Toxicity -‐ 24 h post dosing Fundulus Larval Mortality
Laboratory Spiked -‐ 48 h
Mesocosm -‐ 48 h
YES1,2
YES1,2,3 YES2,3
YES2
YES1,2,3
YES
1Joel Meyer 2Paul Bertsch and Jason Unrine 3Bernhardt, Richardson & Gunsch 4Hunt
YES2
Bioaccumulation & Trophic Transfer of NPs
~100 mg kg-1
Trophic transfer & dilution of Au NPs
Rana catesbeiana
Eisenia fetida
~10 mg kg-1
Unrine et al. ES&T 2012
<1 mg kg-1
Aggregation, Transport and Surface affinity
Aggregation: Dissolution Reactivity Photo-catalysis Molecular Adsorption transport
Deposition: Environmental dispersal Biouptake Translocation in organisms
€
dnk
dt=
1
2α β i, j( )nin j
i+ j→k
∑ −αnk β i,k( )i
∑ ni
+/- breakup –settling – dissolution…
Hotze et al., Langmuir 2010, 26(13), 11170–11175 Jassby et al., Environ. Sci. Technol. 2012, 46, 6934−6941
Measuring surface affinity (alpha) in model systems
detector
data acquisition
gear pump
feed solution
syringe pump
flow measurement
porous medium
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 1 2 3
C/Co
Pore Volumes
Breakthrough curves GB
0.001
0.005
0.01
0.02
0.03
0.05
Tracer
Measuring surface affinity in complex systems
dnk
dt=
1
2α β i, j( )ninj
i+ j→k
∑ −αnk β i, k( )i
∑ ni − breakup
ln γB+1( ) =αβ n, B( )Bt
Barton et al., ENVIRONMENTAL ENGINEERING SCIENCE Volume 31, Number 7, 2014
Transformed distribution coefficient aggregation time
ln γB+1( ) =αβ n, B( )Bt
Barton et al., ENVIRONMENTAL ENGINEERING SCIENCE Volume 31, Number 7, 2014
Importance of surface affinity for transformtion: CeO2
CeO2
CeO2-citrate stabilized
Barton et al. 2014 (in review)
Ag NP Embryotoxicity across a Salinity Gradient – The Role of CoaJngs and Dissolved Silver
Atlan?c killifish Fundulus heteroclitus
1
10
100
1000
10000
0 0.1 0.5 1 5 10
Hydrod
ynam
ic Diameter (n
m)
Salinity (‰)
Colloidal Stability
Ag-‐PVP 100 mg/L Ag-‐citrate 50 mg/L Ag-‐GA 5 mg/L
• Ag NP coa?ngs significantly affect par?cle behavior • Stability/Aggrega?on (Ag-‐gum arabic most stable) • Toxicity (Ag-‐gum arabic most toxic)
• Dissolved silver and silver specia?on play a significant role in toxicity
• Toxicity curve shape related to silver specia?on (total dissolved Ag, not Ag+)
0%
20%
40%
60%
80%
100%
0 0.1 0.5 1 5 10
Mortality (+/-‐ SE)
Salinity ‰
Toxicity
CHESS Model Dissolved Ag
AgNO3 4 µM
Ag-‐PVP 50 mg/L
Ag-‐citrate 50 mg/L
Ag-‐GA 5 mg/L
Auffan et al., Nanotoxicology, 2013, Bone et al, ES&T 2012
GA PVP
CIT
GA
CIT PVP
Examples of nanoparticle reactivity
Effect Underlying reaction
Toxicity to plants and fish by nano Ag Nano silver dissolution
Viral inactivation by fullerol Singlet oxygen generation
Bacterial inactivation by CeO2 Ce reduction
n
B
n-B n*
P
B*
1!! =
1!!"# +
1!!"!"#!
!! =!!"#!!"!"#!!"# + !!"!"#!
heteroäggregation reaction
Importance of surface affinity for transformtion: CeO2
Alpha = 0.16
Alpha = 0.07
Barton et al. 2014 (in review)
Summary
1. Need for functional assays (like surface affinity) for key processes (Transport, transformation, bioüptake…)
2. Many interactions between nano-scale materials, organisms and ecosystems- RICH SCIENTIFIC TERRAIN
Some take home points:(WPB addition, based on summary comments from MRW)
• Nanoparticles (whether engineered [“ENPs”] or natural):can be taken up by plants and animals;
• NPs are subject to trophic transfer‐ in some cases with biomagnification, in some with dilution;
• Attachment efficiencies appear to be a promising way of predicting NP behavior.
• The toxicity issue is secondary.Most important ‐‐ growing awareness of:• Complexity of nanometric phases in their interactions with living systems; and• Potentially important roles of NPs in uptake of chemicals, nutrient cycling, transport of other species, etc.
Thank You
Greg Mélanie Jason Lowry Auffan Unrine Jean-Yves Christine Bottero Hendren
Paul Bertsch Mike Hochella Rich Di Giulio Cole Matson Emily Bernhardt Liz Casman Joel Meyer Peter Vikesland Clement Levard Gordon Brown Paul Westerhoff Olga Tsyusko
Raju Badireddy Shihong Lin Yao Xiao Fabienne Schwab Lauren Barton Mathieu Terezien Jeff Farner David Jassby Benjamin Espinasse Charles De Lannoy Alexis Carpenter Amalia Turner