In situ Phytoremediation of a Historically Contaminated Soil by Heavy Metals and Polychlorobiphenyl

In the last years, intense industrial and agricultural activities have led to serious environmental pollution, resulting in a large number of contaminated sites. Several recent research activities have been focused on the application of bioremediation technologies as environmental friendly and economically feasible for decontamination of polluted soil. In this study horse manure (HM treatment) and horse manure plus Populus nigra (var.italica) (HM+P treatment) were used, at real scale level, as an ecological approach to bioremediate a soil historically contaminated by heavy metals (Pb, Cr, Cd, Zn, Cu and Ni) and organic contaminats (polychlorobiphenyls and total petroleum hydrocarbon). After one year, the phytotreatment was effective in the reclamation of the polluted soil from both organic and inorganic contaminants. A reduction of about 80% in total petroleum hydrocarbon (TPH), and 60% in polychlorobiphenyls (PCB) and total heavy metals was, in fact, observed in the HM+P treatment. On the contrary, in the HM treatment only a reduction of about 30% of TPH was showed. In the attempts to assess both effectiveness and evolution of the remediation system toward a biologically active soil ecosystem, besides the pollution parameters, also parameters describing the evolution of the soil functionality (enzymatic activities and protein SDP-page pattern) were investigated. Dehydrogenase activity is considered an indicator of overall microbial activity and can be involved also in the decomposition and detoxification by contaminants. Moreover, differences in protein pattern on SDS-page could be useful to identify the effects of the pollutants on protein composition. In this study, a stimulation of the metabolic soil processes (increase of dehydrogenase activity) was observed in the planted compared to untreated soil. Finally, preliminary protein SDS-page results have permitted the identification of proteins that have been recovered in planted soil with respect to an untreated soil; this may become a basic tool for improving the biogeochemical status of soil during the decontamination. In addition, the combination of mass spectrometry and protein database could identify the microbial populations that are active in soil decontamination.