Spatial variation of trace elements in the peri-urban soil of Madrid
PURPOSE: The peri-urban region to the south east of Madrid contains a mixture of housing, manufacturing industry and farming, some of which disperse metals, in particular cadmium, copper, lead, and zinc, into the soil. We have mapped the concentrations of these elements and identified the major influences on their distributions. MATERIAL AND METHODS: We sampled the topsoil at 125 sites across 1,050� km² of peri-urban land to the south east of the city on two grids, one nested inside the other. At each site, we measured the current contents of the four trace elements in the soil.