Abstract
The characterization of passive liquid area sources for the study of Volatile Organic Compounds (VOCs) emission is a matter of great concern. The volatilization of these compounds, which very often cause odour annoyance, is a complex phenomenon, being potentially affected by different parameters. For instance, a parameter of great concern is represented by the wind velocity since the convective mechanism, promoted by the wind, represents the driving force of the emission. In view of this, the present paper aimed at investigating the influence of wind velocity on the emission rate of VOCs from liquid surfaces. In particular, acetone is selected as tested compound manly because of its high aqueous solubility. Using this approach, it is possible to test a wide range of concentrations and, consequently, to investigate whether the wind velocity influences the emission rate in a different way by changing the concentration in water. From this experimental study, it turns out that the investigated parameter does not significantly affect the emission when considering low concentrations of acetone (i.e. below 5 mL/L), whereas this dependence increases, not linearly, while increasing the concentration in liquid phase. Due to this, the approach suggested by the Italian guidelines to take into account a dependence of the odour emission rate on the square root of the wind velocity appears quite consistent with the experimental results obtained at higher concentrations, whereas in more diluted conditions the regulatory approach seems too conservative, with the risk of overestimating the emission rate excessively.
