Contamination from historic metal mines and the need for non-invasive remediation techniques: a case study from Southwest England

Abstract

The UK is legally required by the EU Water Framework Directive (WFD) to improve the environmental quality of inland and coastal waters in the coming years. Historic metal mine sites are recognised as an important source of some of the elements on the WFD priority chemicals list. Despite their contamination potential, such sites are valued for their heritage and for other cultural and scientific reasons. Remediating historic mining areas to control the contamination of stream waters, whilst also preserving the integrity of the mine site, is a challenge but might be achieved by novel forms of remediation. In this study, we have carried out environmental monitoring at a historic, and culturally-sensitive, lead-silver mine site in southwest England and have undertaken a pilot experiment to investigate the potential for a novel, non-invasive remediation method at the site. Concentrations of Pb and Zn in mine spoil were clearly elevated with geometric mean concentrations of 6,888 and 710 microg g(-1), respectively. Mean concentrations of Pb in stream waters were between 21 and 54 microg l(-1), in exceedance of the WFD environmental quality standard (EQS) of 7.2 microg l(-1) (annual average). Mean Zn concentrations in water were between 30 and 97 microg l(-1), compared to the UK EQS of 66.5 microg l(-1) (average). Stream sediments within, and downstream from, the mining site were similarly elevated, indicating transport of mine waste particles into and within the stream. We undertook a simple trial to investigate the potential of hydroxyapatite, in the form of bonemeal, to passively remove the Pb and Zn, from the stream waters. After percolating through bonemeal in a leaching column, 96-99% of the dissolved Pb and Zn in stream water samples was removed.

Abandoned metal mines and their impact on receiving waters: A case study from Southwest England

“…Total metal concentrations measured in the sediment samples (Table A6 supplementary material) were comparable with previous research by Rieuwerts et al (2009), who reported mean concentrations of Pb and Zn equal to 2,909 mg kg -1 and 564 mg kg -1 respectively.…”

“…Pirrie et al, 2003;Rieuwerts et al, 2014;Hudson-Edwards et al, 1996). For example, in many areas of the UK, such as southwest England and other parts of Europe, evidence of uncontrolled historic mining activities has shown to have a large and lasting impact (Galan et al, 2003;Nieto et al, 2006;Rieuwerts et al, 2009). Discharge of metal rich water from abandoned mines to surface and groundwater, and contamination of soils and sediments through associated industrial activity are among the highest recorded in the UK.…”

“…Dissolved metals and metalloids may enter the surface waters from point sources such as mine adits and from diffuse sources; mainly rainwater which has percolated through spoil heaps and leached metals and metalloids therein (Galan et al, 2003;Nieto et al, 2006;Rieuwerts et al, 2009). Metals in runoff from spoil heaps may enter receiving waters as dissolved minerals or adsorbed to particulates, which are transported downstream and deposited by river processes (Jarvis et al, 2006).…”

The Impairment of River Systems by Metal Mine Contamination: A Review Including Remediation Options

“…Working Party, 1978), based on species' tolerance to acidity and metal 769 contamination, has also been suggested (Gray and Delaney, 2008) and somesuccess has been achieved using a multi-metric approach by considering 771 multiple biological metrics simultaneously (e.g., Clews and Ormerod, 2009 More subtle community alterations as a result of physiological or behavioural 780 changes are less easy to diagnose (Younger and Wolkersdorfer, 2004) (Table 781 3). For example, Petersen and Petersen (1983) Clements et al (1989) reported that high copper doses increased predation 792 pressure, so much that the numbers of caddisfly, mayfly and chironomids 793 were dramatically reduced. Maltby and Naylor (1990) can be concentrated or magnified in the food chain (Sola et al, 2004) (Table 841 3).…”

Treatment of mine water for the fast removal of zinc and lead by wood ash amended biochar

“…Active and abandoned mines are a major source of contamination for both terrestrial and aquatic environments 1 . Water pollution from these mines can originate from point sources such as mine adits, or diffuse sources such as spoil heaps 2 . In the UK, the potential contamination by mines is compounded by the fact that owners of mines abandoned before 1999 bear no responsibility for their impacts.…”