Effects of Metal Contamination on Physical-Chemical Properties and Microbial Activities in Phragmites Australis Cav. rizosphere along the Sarno River (Italy)

The Sarno River is one of the most polluted rivers in Italy (Campania region) marked by the presence of tanneries and skin processing factories located along its course and the large-scale dumping of untreated agricultural and industrial waste, in addition to domestic effluents. The aim of this work is to provide a preliminary analysis of the rizosphere of Phragmites australis Cav., interstitial and above waters. The metal contents (Cd, Cr, Cu, Ni, Pb, V, Zn and Fe, Mn) were evaluated together with their possible relationships with the physical-chemical properties of the rizosphere samples from along the river and its tributaries, which are now almost entirely fed by urban and industrial waste. With the aim to assess the possible relationships with microbial communities and their possible responses to perturbations, some enzyme activities in the rhizosphere sediments were assayed (acid and alkaline phosphatase, protease, β-glucosidase and peroxidase). The data obtained were compared to Interim Sediment Quality Guidelines (ISQGs), and a “Pollution Load Index” (PLI) was also calculated for each site. Assay analysis, in particular the activity of peroxidase, which was positively correlated with metals, showed a high level of stress. The PLI evaluated showed a progressive level of contamination from the source of the Sarno River to the delta.