Abstract
Nature-Based Solutions (NBS) such as community allotments are increasingly recommended by policymakers to counter urban issues. However, poor quality urban soil often negatively impacts key NBS outputs such as food production, therefore improving urban soil quality is crucial for establishing effective NBS. This may be achieved through use of locally sourced soil amendments. This research, in conjunction with the EU Horizon 2020 UPSURGE project (2020), investigated application of soil amendments in Belfast, Northern Ireland, to improve NBS efficacy. The research explored three agroecological NBS attributes: (1) Plant health: This study investigated the effects of Potentially-Toxic Element (PTE)-rich digestate biochar and basalt dust on soil PTE phytoavailability, phytoaccumulation, and phytotoxicity in mustard (Brassica juncea) and clover (Trifolium pratense) agrisystems. Soil amendments had few significant effects on plant PTE uptake and health. (2) Human health risks: This study characterised Pb ingestion risks in soils and vegetables from no-crop, lettuce, carrot, and garlic agrisystems amended with 5%w/w digestate biochar, using the Unified BARGE Bioaccessibility Method and health risk indices. Biochar reduced bioaccessible soil Pb in some no-crop, carrot, and garlic agrisystem soils, though had no significant effects on vegetable Pb ingestion risks. (3) Carbon cycling: This study investigated the influence of digestate biochar and basalt dust on soil carbon stock, soil carbon and nitrogen isotopes, and soil CO2 efflux in clover and mustard agrisystems over 12 months. Amendments had minimal effect on stored soil carbon stock and isotopes, however basalt increased soil carbon efflux compared to control. Ultimately, this collective research indicated that soil amendments do not universally improve NBS efficacy. Here, locally-sourced amendments may have been less effective as amendment characteristics are similar to soil characteristics. This highlights the need to undertake specific site soil characterisations to support effective implementation of urban NBS amendments.Thesis is embargoed until 31 December 2030.
| Date of Award | Dec 2025 |
|---|---|
| Original language | English |
| Awarding Institution |
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| Sponsors | Engineering and Physical Sciences Research Council & EU Horizon 2020 |
| Supervisor | Siobhan Cox (Supervisor), Rory Doherty (Supervisor) & Neil Ogle (Supervisor) |
Keywords
- Nature based solutions
- urban soils
- contaminants
- human health risk assessment
- carbon
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