Arsenic zoning in a coastal area of the Mediterranean Sea as a base for management and recovery of areas contaminated by old mining activities

The mining activity that has taken place in the mining district of the Sierra Minera of Cartagena-La Unión in the SE Spain has caused a great dispersion of potentially dangerous elements (As, Cd, Cu, Pb, Zn), which requires zoning of the affected area as the basis for correct management. These elements include the arsenic (As) which is considered a carcinogen, mutagen and teratogen and it causes the public health problems. The arsenic content of the soil was chosen for a survey in which both total values and those obtained in different mobilisation trials have been taken into account. The results show that there is spatial variability in the contents of As (5000–15 mgkg−1) depending on the distance to the emitting sources of contamination. Based on these data, a classification is made into four categories of action: maximum, medium, minimum and no priority, coinciding with classes IV, III, II and I, respectively. Slope areas covered in mining tailings in the Sierra Minera, Technosols and Leptosols, as well as the channels of the temporary watercourses, with their high contents in arsenic and heavy metals, constitute the priority areas for the management of soil recovery programmes. These are areas that act as pathways from the primary sources of contamination to coastal zones of the Mar Menor lagoon and the Mediterranean Sea. •Areas affected by mining activities are classified depending on arsenic distribution.•The risk posed by arsenic mobility is strongly affected by soil and sediment mineralogy.•Limestone materials decrease arsenic mobility.•Mobility and bioaccessibility studies are mandatory for the management of these areas.