Baselines for trace elements and evaluation of environmental risk in soils of Almería (SE Spain)

This work seeks to establish baselines for As, Co, Cu, Cr, Cd, Hg, Ni, Pb and Zn, as well as to evaluate the possible anomalies present in the province of Almería (SE Spain), an area geochemically characterized by hydrothermal and volcanic episodes from the Miocene to the Holocene. Both As and Pb exceeded the Soil-Screening Levels (SSLs) established for Andalusia (SSL As = 24 mg·kg− 1; SSL Pb = 400 mg·kg− 1) [Aguilar, J., Dorronsoro, C., Fernández, J.A., Sierra, M., Galán, E., González, I., Bellinfante, N., Aparicio, P., Gómez, J.L., García, T., 2006. Definición de Niveles Genéricos de Referencia para Elementos Traza en la Comunidad Andaluza y Procedimiento de Evaluación de Emplazamientos Afectados por este tipo de Contaminante. Consejería de Medio Ambiente Junta de Andalucía, Sevilla]. The variation in the concentration of these two elements was analysed according to depth, their fractionation in the soil was studied by the BCR technique, and the bivariate correlations between them were made in order to discriminate their geogenic or anthropic origin. The results lead us to conclude that both elements had mainly a geogenic origin, influenced by past geological activity. The As presented the residual fraction above 90% in the cases studied, and therefore the real dangers under current soil conditions proved consistently low. Despite its geogenic origin, Pb presented very high total concentrations in the Sierra de Gádor, with a maximum higher than 5000 mg·kg− 1. Nevertheless, given the low mobility of Pb under oxidant and alkaline conditions, we consider that the zone should be subjected to periodic controls to monitor the mobility of Pb in the soil.