MacDonald, J (2025) Geochemistry and leaching behaviour of potentially toxic elements in coastal legacy landfill sites across North West England and North Wales. Other thesis, Liverpool John Moores University.

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Abstract

Historic industry dating back to the Industrial Revolution from the 19th century onwards is responsible for the presence of PTE (potentially toxic element) concentrations within the coastal environment, of which colliery and steel industries were a considerable contributor. The increasing impacts of climate change on the coastal environment, as evidenced by a continuous global increase in sea level, elevated rates of coastal erosion and coastal flooding, alongside an increasing frequency and intensity of extreme weather events poses a serious threat to mobilisation of hazardous elements, subsequently dispersing into nearby sensitive environmental receptors including: SSSI’s, RAMSAR sites, and designated bathing zones. As there are limited studies addressing the mobilisation of elements pertaining to coastal legacy waste sites in saline and representative rainwater conditions, this study focuses on establishing the total element concentrations of coastal legacy waste sites associated with colliery and/or steel waste across North West England and North Wales, and to determine the level of mobilisation of element concentrations under deionised water, artificial rainwater (ARW), and artificial seawater (ASW) conditions. It was found that across colliery and steel slag-based waste, V, Cr, Se, Ni, As, and Cu exceeded sediment guideline values across the majority of sample sites, thereby establishing these waste sites as significantly hazardous. Furthermore, leaching under deionised water conditions proved most concerning, with leached As, Pb, Al, and Mn exceeded WHO drinking water quality guideline values. Moreover, ARW and ASW leachants displayed significantly reduced leaching in contrast to deionised water leachant. As such, leaching mechanisms only attributable to deionised water conditions such as the low ionic strength of the leachant is likely the primary cause of element mobilisation. The findings of this study imply that leaching of significantly hazardous elements under saline and mildly acidic ARW conditions did not contribute to considerable leaching of elements in complex legacy waste sediments. Moreover, stark differences in concentrations seen within deionised water compared with artificial leachate highlight the need for adaptations to be made to the British standard leaching method (BS EN 12457-2-2002), as studies using this method may overestimate/underestimate element leaching potential under oxidised conditions.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Landfill geochemistry; Legacy landfill; Potentially toxic elements; Leaching behaviour; Leaching; Leachate; Artificial rainwater; Artificial seawater; BS EN 12457-2-2002
Subjects:	G Geography. Anthropology. Recreation > G Geography (General)
Divisions:	Biological and Environmental Sciences (from Sep 19)
SWORD Depositor:	A Symplectic
Date Deposited:	20 Jan 2025 10:05
Last Modified:	20 Jan 2025 10:06
DOI or ID number:	10.24377/LJMU.t.00025196
Supervisors:	Byrne, P
URI:	https://researchonline.ljmu.ac.uk/id/eprint/25196

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