Investigation of zinc nanoparticles in soil environments

Draper, Rebecca (2021) Investigation of zinc nanoparticles in soil environments. PhD thesis, University of Nottingham.

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Nanoparticles (NPs) are materials that have at least one dimension between 1 – 100 nm. Zinc oxide (ZnO) NPs have properties such as UV-light absorption that make them suitable for adding to personal care products. Many ZnO NP-containing products are routinely rinsed into household wastewater and the resulting zinc NP-containing biosolids frequently used to fertilise agricultural soils.

This thesis aimed to investigate potential methods to detect and analyse zinc NPs in natural soil environments as a result of biosolid application. For this, two different strategies were used. The first intended to look at the mechanism of zinc NP dissolution and fixation in soils by developing methods based on dialysis and size exclusion chromatography (SEC). The second aimed to grow plants on soils spiked with different zinc NPs in order to observe differences in various parameters.

Preliminary experimental work focused on method development and determined that NPs can exhibit different behaviours in different solutions and can readily adsorb to equipment surfaces. It was also found that SEC suffered severely from zinc NP column adsorption which persisted despite many attempts to rectify the issue and attempts to use dialysis experienced similar issues.

Following this, experimental work shifted focus to investigate the different behaviours of ZnO NPs, ZnSO4, ZnS NPs and Zn3(PO4)2 in soil and ryegrass. Pristine ZnO NPs were shown to dissolve quickly in soil and followed a similar pattern to ZnSO4 for ZnDTPA, but sequential fractionation results revealed that they behaved differently to ZnSO4.

ZnO NPs also reacted differently to aged ZnS NP and Zn3(PO4)2 particles, which did dissolve, but very slowly. This experiment indicated that ZnS NPs could potentially be safe for crops while still providing nutrition, which would make them useful as a potential method of fertilisation.

The next experiment examined the same four zinc species with AMF and wheat. Results suggested that ZnS NPs could potentially provide a long-term supply of zinc that supports the biofortification of cereal grains while also avoiding issues of toxicity that can be associated with ZnSO4 or ZnO NP fertilisers.

Overall, both these experiments highlighted that it is not applicable to test ZnO NPs and subsequently apply the results to aged particles. Studies using ZnO NPs are likely to observe fast NP dissolution and high zinc availability, potentially leading to concerns over zinc toxicity that may not have been raised if appropriately aged particles had been used instead.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Tye, Andy
Young, Scott
Bailey, Liz
Keywords: Zinc nanoparticles, Soil environments
Subjects: S Agriculture > S Agriculture (General)
Faculties/Schools: UK Campuses > Faculty of Science > School of Biosciences
Item ID: 66748
Depositing User: Draper, Rebecca
Date Deposited: 08 Dec 2021 04:40
Last Modified: 08 Dec 2021 04:40

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