Assessment of mining soil improvement after construction and demolition wastes amendment additions evaluated by microbiological analysis

Major environmental problems in metallic mining areas come from the hazard of metal
pollution of surrounding areas. Therefore, an appropriated management of these soils is
necessary for minimizing the associated risks. Some properties of mining soils, such as
elevated metal concentrations, pH and shortage of essential nutrients make them a poor
medium for organism growth. Therefore, in order to make a stabilization of these mining
areas, it is necessary to solve previously some adverse physical and chemical soil factors
mainly associated to toxic heavy metals and soil structure. Thus, some wastes such as
carbonate, demolition wastes and sewage sludge, were added to soils to provide the needed
conditions for improving soil conditions. The aim of this research was to assess the soil
evolution after amendments addition in a research area placed in the Cartagena-La Unión
Mining District, SE Spain. This assessment was carried out by means of microbial community
evolution and variation as an indicator of soil changes. Mining soils showed, in general, low
numbers of microorganisms, and significant increases in microbial populations were observed
after soil treatment.