Airborne potentially toxic elements (PTEs) are persistent pollutants that pose a threat to
human health. Plants serve as a sink for airborne PTEs and so can be used as bioindicators of
air quality. However, there is a lack of consensus regarding selection of appropriate plant
species, whilst variations in analytical methods make it difficult to compare results of different
studies. This research optimized a method for preparation of bioindicator plant samples for
microwave-assisted digestion and ICP-MS analysis, then applied it to study airborne PTEs in
outdoor and indoor settings. A miniaturisation experiment indicated that either 0.1 g or 0.2 g
samples produced consistent results for all the PTEs studied when digested in 20 mL of nitric
acid. A stainless-steel grinder was preferred to hand grinding or use of a mortar and pestle in
the comminution of moss, lichen, pine needles and rhododendron samples. The optimal plant
washing regime was sequential treatment with Tween80, 1 M HCl, then deionized water
(washing is required since the amounts of PTE deposited on plant surfaces are determined by
difference between results obtained for unwashed and washed samples). The effect of rainfall
on PTE retention on three outdoor bioindicator plants with contrasting textures was studied.
Loss of PTEs was significant in hairy-textured samples, while the waxy-textured foliage was
least affected. The behavior of bark depended on whether it was rough or smooth. Finally,
indoor airborne PTEs were monitored over a three-month period in three university buildings
using Peace Lily (Spathiphyllum Kochii). Levels of PTEs increased over time and were similar
in all three buildings (except for Ni). This suggests that the age of the building was not the main factor affecting the composition of dust deposited, but rather a common source such as
the high background levels of PTEs in the urban soils of Glasgow.
| Date of Award | 6 Sept 2024 |
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| Original language | English |
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| Awarding Institution | - University Of Strathclyde
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| Sponsors | University of Strathclyde |
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| Supervisor | Christine Davidson (Supervisor) & Alison Nordon (Supervisor) |
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