Challenging Habitat

Let me take you to an excursion to the origin of this blog: I started writing about my thoughts on mining and its legacy in the UK and beyond. I wrote about the soils contaminated by metal mining and how lichens and mosses start natural succession in the most challenging habitats. There were posts on the toxicity of legacy mine sites and their effect on the wider environment, especially rivers, as well as touched on social and health aspects of the industry.

Together with two colleagues¹ and two MSc students² at University of Plymouth, I have taken up this latter thread again with a scientific risk assessment for people who frequent legacy mine sites contaminated with arsenic and metals for recreation or work.

Specifically, our research focused on the mining complex of Devon Great Consols in the Tamar Valley Area of Oustanding Beauty (AONB), an area of 67 hectare that is part of the UNESCO World Heritage Site ‘Cornwall and West Devon Mining Landscape‘. The mining history of Devon Great Consols began in the 16th century and ended in 1985 and broke several records, including ‘largest sulfide lode in West England’, ‘largest copper producer’ in the 1850s and in the 1870s, ‘largest arsenic producer’ in the world.

The mine generated great wealth for its owners and shareholders (Stewart, 2013), which at the time, were not bound to undertake remediation upon mine closure. Yet ores below ground and great heaps of waste materials at surface remain rich in arsenic, copper, zinc, iron, tin, tungsten and a range of other metals. Sporadically, the mine was worked for arsenic, tin and tungsten up to the 1930s and the waste heaps were reworked for copper and tin in the 1940s and 1970s. The site remains heavily contaminated, as documented by many scientific publications by the British Geologic Survey and others.

The relatively recent disturbance by mining activities, car rallies (!) and mountain biking combined with the toxic nature of the material means that vast areas remain bare of vegetation. This leaves the toxic waste vulnerable to erosion by wind, rain and frost.

A substantial proportion of the 67 hectare site is less contaminated than the waste heaps and much of that is under woodland management. However, some of the work areas are close to or directly on land covered in mine waste. Moreover, the area has been opened up to the public for walking, biking, horse riding, learning and picnicking on and along a network of 25 km of trails, put in place by the Mining Heritage Project of the Tamar Valley AONB. Arsenic is still abundant on site and it is highly toxic and carcinogenic, as I detailed in a previous blog post and is a major chronic health concern in many areas of the world (e.g. Ratnaike, 2003; World Health Organisation)

The question is obvious: how safe is it today to work here or visit this place for recreation?

Our research investigated the risk to health associated with spending time at Devon Great Consols. We re-assessed general levels of contamination, what happens to arsenic in the human body when the waste material is ingested or inhaled.

We found that parts of the site accessible to the public greatly exceed soil guideline values for arsenic and that exposure of visitors and employees is greater than the dose of minimal risk to health. This led us to urge mining areas to be more thoroughly mitigated before being repurposed and opened to the public.

Our work has been published in the peer-reviewed scientific journal “Environmental Pollution“, which I have summarised for non-scientists in a related post: Arsenic Health Risk at UK World Heritage Site.

Footnotes

¹ Dr Andrew Turner, Associate Professor in Environmental Science and
Mr Jamie Quinn, cartographer at the University of Plymouth, UK
² Ms Xiaqing Chen and Mr Daniel Chester-Sterne, both graduates of MSc Environmental Consultancy at the University of Plymouth, UK

Image

MSc students at the base of Anna Maria waste tip at Devon Great Consols mine, 2018. Image by C Braungardt.

References

Braungardt C, Chen X, Chester-Sterne D, Quinn JGA, Turner A (2020). Arsenic concentrations, distributions and bioaccessibilities at a UNESCO World Heritage Site (Devon Great Consols, Cornwall and West Devon Mining Landscape). Environmental Pollution 264. Accessible for free of charge from the publisher until 5th July 2020 at: https://authors.elsevier.com/a/1b18AzLNSVgDK
After that date, please contact me directly for an electronic copy at cbraungardt@plymouth.ac.uk

Ratnaike RN (2003) Acute and chronic arsenic toxicity. Postgraduate Medical Journal 79:391-396. [link]

Stewart RJ (2013) Devon Great Consols. A Mine of Mines. The Trevithick Society, Camborne. Obtainable from The Trevithick Society [link]