Occurrence and distribution of key potentially toxic elements (PTEs) in agricultural soils: a paradigmatic case study in an area affected by illegal landfills

Principal factor analysis (PFA) shows that soil organic matter (SOM) is the most important sink for the investigated PTEs, suggesting that their occurrence and distribution have a mainly pedogenic control. From this point of view, SOM acts as a sink of PTE by secondary accumulation processes, most probably favoured by the formation of organo-metal complexes. This suggests that PTEs linked to SOM can substantially arise from the weathering of the geogenic PTE forms, as well as unintentional or illegal “anthropogenic” factors may influence the whole soil PTEs pool. Indeed, such findings do not exclude that some PTE accumulation in the investigated soils may also have been due to anthropogenic sources. As a matter of fact, given the long-standing human impact on the investigated area, an anthropogenic influence on PTE background concentrations cannot be a priori excluded. From this point of view, the agricultural soils of Volturno River's lower basin require strict control and protection from the illegal deposition of waste materials, in order to prevent the widespread diffusion of pollution.