Dry Deposition Inferential Measurement in a Rural Region of Northern Italy

ENEL SpA/ CRAM, Environment and Material Research Centre of the Italian Electricity Company, in collaboration with the Environmental Department of CISE, has been developing a long term project since 1992, in order to evaluate the contribution of deposition phenomena in the environmental problems related to atmospheric acidity. This activity is carried out at the meteorological station of San Pietro Capofiume, located in the Po river plain, a rural region in northern Italy affected by anthropogenic pollution events. This project also aims to study dry deposition over a long period in the Mediterranean area. Direct measurements of meteorological and chemical parameters were used to run inferential technique models, in order to quantify dry deposition. The big-leaf and multi-layer approaches were both tested. Concentrations of SO₂, NO₂, NO and O₃ were measured with half an hour resolution, using automatic analysers. During the vegetative season, concentration of gaseous species as SO₂, NO₂, HNO₂, HNO₃, NH₃ and fine particulate as SO₄2− NO₃− and NH₄+ were measured weekly, by an annular denuder system. In 1993, during the vegetative season, an intercomparison campaign was performed at S. Pietro Capofiume to test an inferential technique against eddy correlation ozone fluxes. The results of this comparison and the annual dry deposition fluxes are presented.