[The Manfredonia case 40 years after: measurements and modelling of arsenic deposition].

Abstract

One of the main aim of the participate research carried out in Manfredonia (Apulia Region, Southern Italy) was to evaluate the exposure to the arsenic released during the industrial accident occurred in 1976, by reconstructing the event and the extent of contamination through an analysis of all the collected environmental data, the information issued from the participated research group, and the execution of meteo-dispersive simulation. The emission form the blown-out column consisted of two fractions. The first fraction was a mix of liquid and solid material fallen in the area of the plant, with peaks of deposition exceeded 1,500 mg/kg of arsenic, to which mainly workers are exposed. The second fraction was a cloud which was dispersed and carried by the wind beyond the plant area, towards the town. This second fraction was calculated using meteorological simulations and short-term dispersion simulations (a few hours). The map of ground deposition is in accordance with the maps created out of the first deposition measurement of the ground (correlation index: 0.67), although this map identifies a larger area of contamination. Both measured and modelled depositions show a maximum deposition 2 km away from the outburst site. The reconstructed deposition map gives a contamination value with a gradient in the populated area, that is a relevant instrument to evaluate citizens exposition.