Determination of the parameters for the calculation of dry and wet deposition of chemicals in the Povitrya system

Abstract

The previously developed system Povitrya allows the calculation of the atmospheric distribu-tion of 36 chemicals using the CALPUFF atmospheric dispersion model. In this paper, after the literature review and according to the requirements of the CALPUFF model, the values of the parameters for the calculation of dry and wet depositions of pollutants in the Povitrya system have been defined. Based on the analysis of the model parameters, the parameters that depend on the type of substance have been identified. For pollutants that spread in the form of aerosols, only one parameter – the scavenging coefficient included in the formula for the calculation of wet deposition – depends on the type of substance. Other deposition parameters for aerosols are a function of the characteristics of the particle size distribution, so they are not considered in this paper. The scavenging coefficient is specified for all types of chemicals – aerosols and gas-es modeled by the Povitrya system depending on the solubility of the substance (for gases) or miscibility (for aerosols). For gases, several other parameters in deposition calculation formu-las also depend on the type of substance, namely: molecular diffusivity, solubility enhancement factor, reactivity, mesophyll resistance, and Henry’s law. The values of the corresponding pa-rameters are set for 17 types of gaseous pollutants. To determine Henry’s law constant, there have been established correspondences between the definitions of this parameter in the litera-ture and the CALPUFF model. For mesophyll resistance, an interpolation formula is proposed to calculate this parameter as a function of solubility. The least data was found for reactivity and solubility enhancement coefficient. Therefore, with some exceptions, the values of the rele-vant parameters are set the same for all substances. A more detailed definition of these parame-ters requires a separate study.