Arsenic concentrations, distributions and bioaccessibilities at a UNESCO World Heritage Site (Devon Great Consols, Cornwall and West Devon Mining Landscape)

Abstract

Devon Great Consols (DGC) is a region in south west England where extensive mining for Cu, Sn and As took place in the nineteenth century. Because of its historical and geological significance, DGC has protected status and is part of the Cornwall and West Devon Mining Landscape UNESCO World Heritage Site. Recently, the region was opened up to the public with the construction or redevelopment of various trails, tracks and facilities for walking, cycling and field visits. We used portable x-ray fluorescence spectrometry to measure, in situ, the concentrations of As in soils and dusts in areas that are accessible to the public. Concentrations ranged from about 140 to 75,000 μg g-1 (n = 98), and in all but one case exceeded a Category 4 Screening Level for park-type soil of 179 μg g-1. Samples returned to the laboratory and fractionated to <63 μm were subjected to an in vitro assessment of both oral and inhalable bioaccessibility, with concentrations ranging from <10 to 25,500 μg g-1 and dependent on the precise nature and origin of the sample and the physiological fluid applied. Concentrations of As in PM10 collected along various transects of the region averaged over 30 ng m-3 compared with a typical concentration in UK air of <1 ng m-3. Calculations using default EPA and CLEA estimates and that factor in for bioaccessibility suggest a 6-h visit to the region results in exposure to As well in excess of that of minimum risk. The overall risk is exacerbated for frequent visitors to the region and for workers employed at the site. Based on our observations, we recommend that the remodelling or repurposing of historical mine sites require more stringent management and mitigation measures.