Ag and Ag 2 S NP uptake into alfalfa and duckweed plants. John Stegemeier SNO Meeting 11/4/2013

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1 and 2 S NP uptake into alfalfa and duckweed plants John Stegemeier SNO Meeting 11/4/2013

2 Release Transformed Introduction NP enabled products 2 S NPs Made into Biosolids / Fertilizer Applied to Waste Water Treatment riculture NPs Sent to

3 Motivation Silver nanoparticles were applied to simulated wetland mesocosm Silver was found to transform to silver sulfide Silver sulfide, although significantly less soluble, was found to be bioavailable to plants Lowry, G.V., Espinasse, B.P., Badireddy, A.R., Richardson, C.J., Reinsch, B.C., Bryant, L.D., Bone, A.J., Deonarine, A., Chae, S., Therezien, M., Colman, B.P., Hsu-Kim, H., Bernhardt, E.S., Matson, C.W., Wiesner, M.R., Long-Term Transformation and Fate of Manufactured Nanoparticles in a Simulated Large Scale Freshwater Emergent Wetland. Environ. Sci. Technol. 46,

4 Methods Synthesized: PVP-coated ~15 nm diameter NPs Prepared Fresh sample EtOH fixed 2 S NPs Exposed Alfalfa Medicago sativa + ions Duckweed Lemnoideae Prepared Fresh sample Kapton sealed Water filled pouch

5 Analysis of the root tips Duckweed Alfalfa 0.1 mm 0.4 mm

6 XRF mapping Focus Point Incident X-ray Beam Focusing Mirror Fluorescence Detector

7 XRF mapping Please keep in mind that the scale bars are relative for each image The background can be used as an indicator of signal intensity If the background is blue there are low total counts Maps have a pixel size of 2x2mm Low counts High counts

8 Duckweed root tips after 24h concentrated in the root tip Silver sulfide NPs are not internalized + ion (0) NP 2 S NP

9 Duckweed root tips after 72h Silver is incorporated into the interior of the root Potential root growth or solubilizing exudes + ion (0) NP 2 S NP

10 Alfalfa root tips Silver ion and (0) NP uptake appear similar Silver sulfide is not internalized into root tip Speciation information is needed Supp. + ion (0) NP 2 S NP

11 2S Duckweed All spots investigated were found to contain significant zero valent silver Spot 2 Spot 1

12 Conclusions Samples exposed to silver NP uptake silver in a similar manner and timescale with + ion 2 S adsorbs to the exterior of the roots but is available to the roots (slower uptake) This implies different uptake methods for 2 S and (0) Duckweed and alfalfa uptake particles differently Silver in roots APPEARS to be (0)

13 Acknowledgements NSF / EPA / DOE CEINT Duke Fabienne Schwab Benjamin Colman APS support staff

14 (0) Root embedded Os Os and taken into center of root Yellow = exposed root tip XRF imaged the rest of the sample inside the block Little uptake

15 Conclusions Challenging samples and poor data quality limit further data analysis (spatial-speciation) All spots investigated were found to contain significant (0) Plants may be dissolving and reducing a portion of the 2S nanoparticles Ion uptake is likely the driving force be incorporation into plant tissue

16 2S Root embedded Os Little and diffuse

17 Duckweed control (method testing) can be used to image plant structure Root-Leaf interface Root tip

18 Duck 2S root tip 2S appears outside of root is discrete hot spots not abundant in middle of the root

19 2 S Duckweed Point 3 Point 1 Point 2

20 2S Alfalfa root Spot 2 Spot 1

21 Duck (0) PVP root tip is concentrated in the middle of root Some silver is still outside (halo)

22 Alfalfa (0) PVP leaf hot spots dominate signal (rescaled) Potentially contaminated when loading

23 Alfalfa 2S Leaf Need to identify what species this is

24 Alfalfa control leaf Contaminated!! Probably my fault sorry guys What!?!

25 Alfalfa Control Leaf Same sample quick clean to make sure it wasn t outside the sample

26 Duckweed root tips 24 hour exposed samples concentrated in the root tip Some silver clusters are present

27 Duck (0) GA root tip Appears similar to the silver ion with silver mainly in the interior of the root tips

28 Duck 2 S root tip Silver appears to cluster at the exterior of the root tip Silver does not appear to been internalized by duckweed at 24h

29 Duckweed (0) GA root tip 72 hour aged samples Silver appears to be moving up or the root is growing down (not a comet shape)

30 Duck2 ion root tip Plants had all died by the first exposure

31 Duck2 2S root tip A lot of silver in the interior of the root Potential growth of roots or solubilizing exudes allow incorporation of