Bioaccessibility of arsenic in mine waste-contaminated soils : a case study from an abandoned arsenic mine in SW England (UK)

This study characterises the total As concentrations and As bioaccessibility in 109 soils from Devon Great Consols Mine, an abandoned Cu-As mine in Devon, SW England, UK and discusses the soil and mineralogical factors that influence the bioaccessibility of this element. These data provide the basis for developing more accurate exposure estimates for use in human health risk assessments. The median value of the percent bioaccesible As of 15% for these As rich soils contaminated by mining activities indicated that relatively little of the total As is present in a bioaccessible form. Spatial variability of As bioaccesibility in the soils was also recognised throughout the mine site as a function of mineralogy. Multivariate statistical analysis identified a sulphide component responsible for the reduced As bioaccessibility of one cluster of soils. In the larger cluster of acidic mine soils covered by woodland As is mainly hosted in Fe oxyhydroxides whose partial dissolution is responsible for the bioaccessible As fraction. It was highlighted that the degree of Fe oxyhydroxide crystallinity might represent an important factor influencing arsenic bioaccessibility. Mine soils from Devon Great Consols Mine showed overall higher As bioaccessibility (15%) than other mineralised soils not affected by mining activities and background soils within the Tamar Catchment whose percent bioaccessible As median values were 9%.