Zero Flux Plane and heavy metals contamination in surface layers of urban soils in Bagnolo Mella (Brescia)

In this work we present some activities and results of a field study which took place in the area of Bagnolo Mella, a municipality nearby the city of Brescia (Northern Italy), where a ferroalloy industry has operated in the last forty years. During several field campaigns in Bagnolo Mella the surface—soil heavy—metals concentrations were measured. Measured heavy—metals concentrations were then processed to calculate four of the most commonly accepted soil—pollution indices, and the results were investigated to evaluate the local wind regime influence on the spatial distribution of significantly enriched sites, with respect to the source of pollution. The same indices were used to describe the profiles of heavy metals content measured in four sites, chosen close to the industry, where also the near—saturation hydraulic—conductivity was measured. Considering these four sites, in order to investigate the role of the soil—water regime at partitioning the heavy—metals fluxes, the information given by the pollution indices along the soil profile was compared with an estimate of the limit depth of the zero—flux plane (ZFP), determined by means of Brutsaert's (2015) solution of the linearised Richards equation.