Distribution of the Metals Lead,Cadmium, Copper,and Zinc in the Top Soil of Cartagena,Spain

This article presents the results of the analysis of the metals lead, cadmium, copper, zinc and aluminum, conducted on a total of 112 soil samples arising from 57 sampling points, distributedthroughout the Cartagena area in southeastern Spain. Both, totalmetal content and soluble fraction (1 M nitric acid medium, exchangeable fraction) were analyzed. Soil samples were taken on the surface of the terrain and at a depth of 35 cm from eachsampling point. For the purposes of this study, sampling points were classified in three groups based on the results of previous research on air pollution in the region: clean areas,contaminated areas and vacant industrial areas. The statisticalanalyses of the results show no significant differences betweenthe surface samples and the 35 cm deep samples from all three areas. Lead, zinc and copper (soluble and total fractions) aresignificantly higher, and pH significantly lower, in the samples coming from the contaminated and vacant industrial areasthan in samples coming from the clean area. Total lead and cadmium are significantly higher in the vacant industrial areas(150 g kg^-1 Pb and 9.3 g kg^-1 Cd) than in the contaminated areas (5.2 g kg^-1 Pb and 2.1 g kg^-1 Cd).Iso-concentration maps have been prepared in order to correlatethe presence of metals with the industrial and mining activities in the region under study. These maps show a clear relationship between human activities and metal concentrationgradients, with peaks corresponding to both active and abandoned industrial and mining facilities.