Estudio de metales pesados en suelos agrícolas con cultivos hortícolas de la provincia de Alicante.

Zusammenfassung

Heavy metals appear naturally in agricultural soils according to both the parent rock and pedogenic processes. However, the agroecosystem can be affected by human activities developed in the proximities of these soils and agricultural practices, which can release contaminants such as heavy metals to the environment. Scientific studies are required to assess the content and distribution of heavy metals in soils due to the diversity of sources that can increase the heavy metal content, particularly in agricultural soils, and avoid their degradation. In addition, it is also necessary to establish soil quality standards to distinguish between soils with normal levels of heavy metals and contaminated soils. The general aim of this Doctoral Thesis is to characterise the present condition of agricultural soils with vegetable crops in the province of Alicante (Valencian Community). To achieve this purpose, different specific objectives have been proposed: (1) to analyse properties and characteristics of these agricultural soils; (2) to determine the total and extractable content of nine heavy metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn) in soil samples; (3) to determine heavy metal content in some vegetable crops, specially in those crops cultivated in soils with high content; (4) to study statistical relations (correlation, regression, factorial analysis and cluster analysis) between different variables; and (5) to establish background and reference values of heavy metals for agricultural soils within the Valencian Mediterranean region. The total and extractable content of heavy metals in agricultural soils are similar to other Mediterranean soils, with the exception of some plots that present high total levels of Cr, Cu and Pb, and a high extractable fraction for the Cd, Cu and Pb. On the other hand, the heavy metal content in vegetable crops do not exceed the permissible maximum level established by the European legislation, with the exception of some samples that show high Cd content. Finally, background and reference values for heavy metals have been proposed. The comparative study indicates the 37% of soils exceed the reference values proposed, whereas the 63% of soils show heavy metal content below the reference value and, therefore, they reflect an acceptable quality.