Soil pollution in a decommissioned shooting range: a preliminary survey of the spatial variability of legacy pollutants

Outdoor shooting ranges provide recreational facilities for millions of people in the world. However, there are many negative effects on the environment and public health arising from this activity. In particular, potential risks are mostly associated with the residential or agricultural use of decommissioned outdoor ranges, where bullets and targets have been deposited during the shooting activity. This is the case of an outdoor shooting range in Campania region (Southern Italy), located in an area of historical and naturalistic value, close to the ancient Etruscan village of Suessola (VII century b.C.). Specifically, the study site is located within an agricultural land declared unsuitable for agricultural and forest-pastoral production by the Italian Ministry of Agricultural, Food and Forestry Resources, due to an extensive long term soil contamination associated with Pb, Sb, PAHs, dioxins, PCBs and C> 12 hydrocarbons. With the purpose of planning a detailed site characterization of the shooting range area, a preliminary environmental survey was carried out by means of field investigations (ultrasonic penetrometry, electromagnetic induction - EMI - and gamma spectroscopy) and geochemical prospecting. Cone index data, obtained by ultrasonic penetrometer measurements, indicated the presence of a very dense, hard and impenetrable to hand hauger layer, recognised as travertine rock, from 25 to more than 55 cm of depth, and dipping northward. Continuous EMI data and gamma spectroscopy (K %, eU ppm, eTh ppm) parameters were acquired in the field in order to identify homogeneous zones in which further geochemical investigations should have been focused. In fact, apparent electrical conductivity (ECa) map, consistently with the gamma ray dose rate distribution map, allowed to highlight three separated singularity areas N-S oriented. XRF analyses, carried out through a portable analyzer on soil samples collected along soil profiles digged from topsoil until the travertine layer, showed a high contamination by Pb (greater than 1000 mg/kg) and Sb (greater than 30 mg/kg) in the first 15 cm of depth, at a distance of approximately 90 m from the shooting lanes. Chemical analyses were also performed on 32 topsoil samples collected on the basis of a regular grid across the study area. Concentrations of 13 PAHs compounds were determined and the highest values were found close to the firing lanes where in soil a huge amount of shooting target fragments are present. The preliminary results showed how the contamination due to the previous activity in the area produced a spatial distribution of contaminats differentiated on the basis of their source material and their role in the shooting process.