The development of a surrogate soil to assist the revegetation and stabilisation of metal-mine tailings

Abandoned mines are considered among the most severe of environmental issues, and are a significant danger to environmental, animal, and human health (Mehta et al., 2020). To date, ~ 600,000 abandoned mines exist, the costly reclamation of which often falls to publicly funded bodies (Archer & Caldwell, 2004; Mayes et al., 2009). Traditional reclamation methods are financially unattainable at ~ £50 million per large mine (McKenna, 2002), and an alternative, lower-cost method is required (Garcia, 2008). One contemporary reclamation method found to be effective is that of capping mine waste with a soil cover (O’Kane & Ayres, 2012). In this research, an adhesive surrogate soil capping layer for the hydraulic application to steep-sided metal-mine tailings was developed at the cost of ~ £6 .m-² (at the time of writing). The surrogate soil was refined throughout a series of trials. A rainfall trial was conducted to develop an adhesive and erosion resistant soil material. A germination trial (N = 500) determined the soil materials which best assisted rapid plant establishment. The successful results of these laboratory-based trials guided a nine-month field trial on an abandoned Pb mine, Nantymwyn (UK) (N = 154). The field trial concluded that the surrogate soils effectively resisted erosion and supported the early (seven month) growth of metal-tolerant grass species. The grasses contained Pb, Zn, Cd and Cu concentrations at < 1% of the phytotoxic threshold. However, seasonal climatic events and a negative water balance ultimately led to complete grass mortality after nine months. Tailings bank destabilisation also influenced grass survival. The research revealed that the soil’s available water supply was of greater impact to plant survival than metal toxicity. The results indicated that should the soils water-holding capacity be improved, the application of a carefully designed surrogate soil has the potential to support vegetative cover on steep, bare metal-mine tailings

Biochar for remediating contaminated soils: Outdoor experiments in Wales, UK

Most soil-related applications of biochar have involved agriculture or horticulture. Our current research focusses on remediation of contaminated soils using biochar or biochar compost. We will present the results of outdoor pot and plot trials on three contrasting site types: 1) colliery waste; 2) cleared invasive rhododendron; and 3) metal-mine tailings. All experiments utilized sustainable, lignocellulosic biochar (EarthChar®; UK Biochar Quality Mandate: High Grade), produced using a modified BigChar-1000 fast-pyrolysis/gasification unit equipped with a thermal oxidiser. Please click on the file below for full content of the abstract

Gothic Revival Architecture Before Horace Walpole's Strawberry Hill

The Gothic Revival is generally considered to have begun in eighteenth-century Britain with the construction of Horace Walpole’s villa, Strawberry Hill, Twickenham, in the late 1740s. As this chapter demonstrates, however, Strawberry Hill is in no way the first building, domestic or otherwise, to have recreated, even superficially, some aspect of the form and ornamental style of medieval architecture. Earlier architects who, albeit often combining it with Classicism, worked in the Gothic style include Sir Christopher Wren, Nicholas Hawksmoor, William Kent and Batty Langley, aspects of whose works are explored here. While not an exhaustive survey of pre-1750 Gothic Revival design, the examples considered in this chapter reveal how seventeenth- and eighteenth-century Gothic emerged and evolved over the course of different architects’ careers, and how, by the time that Walpole came to create his own Gothic ‘castle’, there was already in existence in Britain a sustained Gothic Revivalist tradition

The use of a sustainable biochar compost for stabilizing and revegetating metal-mine tailings heaps

Anthropogenic activities, particularly mining and smelting, have led to an increase in heavy-metal pollution harmful to human, animal and environmental health. Metal mining has global-scale impacts, with many mine sites being characterised by bare, steep sided, heavily polluted tailings heaps containing metals such as Zn, Pb, Cu and Cd at toxic concentrations. Their unvegetated slopes are highly erodible, causing fine-grained metals to be widely deposited on floodplains and pastureland after heavy rain. This threat is predicted to increase with future climate change. Our recent research focusses on remediation of these sites using a sustainably sourced, enhanced biochar compost to revegetate and stabilise the steep slopes of the tailings heaps, thereby reducing metal mobility. Please click on the file below for full content of the abstract