Heavy metal content of agricultural soils in a Mediterranean semiarid area: the Segura River Valley (Alicante, Spain)

Abstract

Assessment of the content and sources of heavy metals in soils is required to identify agricultural areas affected by contamination on a regional level, according to the European Thematic Strategy for Soil Protection. The total content of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn of 29 agricultural soils used to grow vegetable crops such as artichoke, broccoli, and potato, in the Segura River Valley, Alicante, Spain, as a representative area of the semiarid Mediterranean region, was determined to assess the current state of heavy metal contamination of agricultural soils. The mean values (mg kg-1) were: Cd, 0.38; Co, 7.9; Cr, 28.3; Cu, 21.6; Fe, 15,274; Mn, 320; Ni, 23.7; Pb, 19.6; and Zn, 57.8. These values followed the sequence: Fe>Mn>Zn>Cr>Ni>Cu>Pb>Co>Cd. Despite intensive production, the soil heavy metal concentrations were equal to, or lower than concentrations determined by others working on Spanish agricultural soils. Nevertheless, some plots had high Cd and Pb concentrations. Based on these results and others from the Spanish Mediterranean region, further studies under semiarid conditions are required to obtain a better knowledge of the pollution levels, especially in the case of anthropogenic metals such as Cd and Pb. This is critical to safeguard the environmental and production functions of these soils and, therefore, their quality. Further, given the importance of vegetables in the Mediterranean diet, it is important to extend the work to other areas of the European Mediterranean region.