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| Titel |
Effect of the background solution and material composition on the transport of silver nanoparticles in saturated aquifer materials |
| VerfasserIn |
Yorck Adrian, Uwe Schneidewind, Tomas Fernandez-Steeger, Rafig Azzam |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250126672
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| Publikation (Nr.) |
 EGU/EGU2016-6428.pdf |
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| Zusammenfassung |
| Engineered silver nanoparticles (AgNP) are used in various consumer products such as cloth
or personal care products due to their antimicrobial properties (Benn et al., 2010). Their
transport behavior in the environment is still under investigation. Previous studies have been
focusing on the transport of AgNP in simple test systems with glass beads or soil materials
(Braun et al., 2015), but studies investigating aquifer material are rare. However, the
protection of fresh water resources in the subsurface is an important part in the protection of
human health and the assurance of future economic activities. Therefore, expert knowledge
regarding the transport and fate of engineered nanoparticles as potential contaminants in
aquifers is essential.
Within the scope of the research project NanoMobil funded by German Federal Ministry of
Education and Research, the transport and retention behavior of AgNP in aquifer material
was investigated under saturated conditions in laboratory columns for different flow
velocities, ionic strengths (IS) and background solutions. The used aquifer material consisted
mainly of quartz and albite. The quartz grains were partially coated with iron hydroxides and
oxides. Furthermore, 1% hematite was present in the silicate dominated aquifer material. The
experiments were conducted using NaNO3 and Ca(NO3)2 background solutions to examine
the effects of monovalent and divalent cations on the transport of AgNP. Flow velocities in
the columns were chosen to represent typical flow velocities of groundwater in
the subsurface. For the experiments two mean grain sizes of 0.3 and 0.7 mm were
used to investigate the effect of the grain size on the transport behavior. Particle
concentration was measured using ICP-MS and particle size was determined using
flow field-flow fractionation (FlFFF). HYDRUS-1D (Šimůnek et al., 2013) was
used to elucidate the transport and retention processes of the AgNP in the aquifer
material.
The obtained results show that grain size and background solution as well as mineral
composition have an effect on the retention of AgNP. A higher breakthrough of about 75%
was observed in the more coarse material compared to 60% in the fine material. Especially,
iron oxides and hydroxides provided favorable attachment points for AgNP. Complete
retention of AgNP in the aquifer material occurred at 1.5 and 1 mM IS when Ca(NO3)2 was
used as background solution and little breakthrough was observed at 0.5 mM IS. In
contrast, when using NaNO3 (1 and 10 mM) a breakthrough of about 50% of the
AgNP was observed for 1 mM IS whereas no breakthrough occurred for 10 mM
IS. The results show that the divalent background ions and a high ionic strength
tend to reduce the transport of silver nanoparticles in aquifer material with this
composition.
References
Benn, T., Cavanagh, B., Hristovski, K., Posner, J. D. and Westerhoff, P. (2010): The release of
nanosilver from consumer products used in the home. Journal of Environmental Quality, 39,
1875-1882.
Braun, A.; Klumpp, E.; Azzam, R. and Neukum, C. (2015): Transport and deposition of
stabilized engineered silver nanoparticles in water saturated loamy sand and silty loam.
Science of the Total Environment, 535, 102-112.
Šimůnek, J., Šenja, M., Saito, H., Sakai, M., and van Genuchten, M. T. (2013), The
Hydrus-1D Software Package for Simulating the Movement of Water, Heat, and
Multiple Solutes in Variably Saturated Media, Version 4.17, 342 pp, Department of
Environmental Sciences, University of California Riverside, Riverside, California, USA. |
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