Geochemical background levels of zinc, cadmium and mercury in anthropically influenced soils located in a semi-arid zone (SE, Spain)

This work seeks to establish the geochemical background for three potentially toxic trace elements (Zn, Cd and Hg) in a pilot zone included in the DesertNet project in the province of Murcia, and subjected to intense anthropic activity. The possible relationship between soil properties and element concentrations has been studied. Although the results showed that no such relationship existed, the concentration of these trace elements was correlated with the mineralogical composition. The background level established for each element was 40 mg kg− 1 for Zn, 0.3 mg kg− 1 for Cd and 0.4 mg kg− 1 for Hg. Four groups were established according to mineralogical composition, and the Zn content is correlated with each mineralogical groups while the Cd and Hg content was not correlated with any group.