Scavenging of radioactive soluble gases from inhomogeneous atmosphere by evaporating rain droplets.
We analyze effects of inhomogeneous concentration and temperature distributions in the atmosphere, rain droplet evaporation and radioactive decay of soluble gases on the rate of trace gas scavenging by rain. We employ a one-dimensional model of precipitation scavenging of radioactive soluble gaseous pollutants that is valid for small gradients and non-uniform initial altitudinal distributions of temperature and concentration in the atmosphere. We assume that conditions of equilibrium evaporation of rain droplets are fulfilled. It is demonstrated that transient altitudinal distribution of concentration under the influence of rain is determined by the linear wave equation that describes propagation of a scavenging wave front. The obtained equation is solved by the method of characteristics. Scavenging coefficients are calculated for wet removal of gaseous iodine-131 and tritiated water vapor (HTO) for the exponential initial distribution of trace gases concentration in the atmosphere and linear temperature distribution. Theoretical predictions of the dependence of the magnitude of the scavenging coefficient on rain intensity for tritiated water vapor are in good agreement with the available atmospheric measurements.
Department of Mechanical Engineering, The Pearlstone Center for Aeronautical Engineering Studies, Ben-Gurion University of the Negev, P.O.B. 653, 84105 Beer-Sheva, Israel. Electronic address: elperin@bgu.ac.il.
Tov
T
Elperin
Department of Mechanical Engineering, The Pearlstone Center for Aeronautical Engineering Studies, Ben-Gurion University of the Negev, P.O.B. 653, 84105 Beer-Sheva, Israel. Electronic address: fominykh@bgu.ac.il.
Andrew
A
Fominykh
Department of Mechanical Engineering, The Pearlstone Center for Aeronautical Engineering Studies, Ben-Gurion University of the Negev, P.O.B. 653, 84105 Beer-Sheva, Israel. Electronic address: borisk@bgu.ac.il.
Boris
B
Krasovitov
D000396:Air Pollutants, Radioactive / Q000032:analysis*; D007457:Iodine Radioisotopes / Q000032:analysis*; D008962:Models, Theoretical; D011834:Radiation Monitoring / Q000379:methods*; D011891:Rain / Q000737:chemistry*; D013227:Steam / Q000032:analysis; D014316:Tritium / Q000032:analysis*
D000396:Air Pollutants, Radioactive; D007457:Iodine Radioisotopes; D013227:Steam; D014316:Tritium
Atmosphere; Droplet evaporation; Gas absorption; Precipitation; Radioactive gases; Scavenging