Mercury soil pollution in Spain: A review

Abstract

Spain has been the main mercury producer worldwide, with mines or mining districts scattered across its geography. In particular, two main areas show generally higher contents of this element in the soils, namely, Asturias (or the Cantabrian Zone in geological terms) and the Almadén area in the Southern Central Iberian Zone. In this review six different aspects are considered: (1) distribution of total concentrations, (2) mercury mobility and availability, (3) soil to plant transfer, (4) mercury transfer to animal biota, (5) soil to atmosphere transfer and (6) possibility of remediation for sites polluted by mercury. The conclusions drawn from the available results highlight significant differences in contents, mobility and transfer processes depending on the different types of mercury pollution and different climatic conditions. A general background level for Spanish soils can be established at 20 μg kg−1, but very different ranges can be found in different areas according to the volumetric importance of each source and depending on other local factors. Mercury mining appears to be the most important source of soil pollution, and studies on the possible mobility and transfer to other environmental compartments demonstrate the highest levels at which mercury affects the population living in the proximity of such sources.