Identifying volatile organic compounds at a rural site in the Italian Po Valley

Volatile organic compounds (VOCs) released into the atmosphere by natural and anthropogenic sources play a key role in atmospheric processes. They can react with atmospheric oxidants leading to secondary organic aerosols and tropospheric ozone, with effects on air pollution, human health and climate.

The Po Valley, located in the North of Italy is a densely populated area influenced by intense agricultural, industrial and urban-related activities, suffering among the worst air pollution in Europe. Although efforts aimed at characterizing the chemical and physical processes influencing aerosols and other atmospheric pollutants have been conducted over the last decades, very little is known about the precursor organic chemical species emitted in this region.

Volatile organic compounds in the mass range 0-400 amu were measured for three weeks in October 2023 at a rural site in Schivenoglia (MN), in central Po Valley, using a Vocus CI-ToF (chemical ionization time of flight) 2R mass spectrometer (Tofwerk, Switzerland). During the measuring campaign, the site was influenced by contrasting meteorological conditions, warm and colder temperatures as well as biomass burning events and the application of manure to fertilize the fields. Over 1000 peaks, corresponding to volatile molecules and their possible fragments were detected in the measured mass spectra. Among the detected peaks, about 500 were tentatively associated to a chemical identity. The concentrations of the identified species are discussed in function of their variability with time, meteorological conditions, and emission sources, in order to elucidate the atmospheric processes influencing VOC concentrations in the Po valley.