On the natural radioactivity in the air

Abstract

The concentrations of the various radioactive decay products of radium in the air have been determined by observing the beta activity (1) of pieces of filter paper through which air has been passed, and (2) of chemically separated isotopes obtained from such filter papers. The relative amounts of long‐lived and short‐lived products found indicate that, besides the radioactive decay of the substances, some other process which removes radioactive particles from the air is active. The mean life of the particles with respect to this removing process is found to be about 10 days. The hypothesis that this process is the capture of the radioactive particles by rain droplets (clouds) is consistent with measurements made of the radioactive content of rain‐water. On the other hand, the removal of the ionized radioactive particles by the electric field of the earth leads to a much smaller effect.

On the Distribution of Sea Salt over the United States and its Removal by Precipitation

“…In a completely different way BLIFFORD, LOCKHART and ROSENSTOCK (1952) and also to the case where the major portion of the aerosols is confined to the lowest levels of the tropos here (as is normal for most natural aerosol5 and not to uniformly distributed aerosols, as in our case of sea spray over continents and in the data of Stewart et al…”

Comparative temporal behavior of radon- and thoron-progeny in surface air over the midwestern U.S.

“…Its atmospheric concentration at a particular location is not directly related to the atmospheric concentration of its parent 222Rn at that site 2 because airborne 21~ can be carried thousands of miles from its point of origin before decaying or being removed by rainout. [3][4][5][6] Concentrations of 21~ in ground level air have been measured at widely separated locations throughout the world L6-9 At many of these locations, including some in the continental U.S., 6-9 distinct seasonal patterns are observed. At other locations, including the U.S. cities of Washington, D.C., and Miami, Florida, month-to-month concentration changes are reported to be erratic with no well-defined seasonal pattern.…”

Application of the variability-size relationship to atmospheric aerosol studies: estimating aerosol lifetimes and ages

“…From the ratio of short-lived to long-lived radon daughters in surface air values on the order of 5 days were deduced (Blifford et al, 1952;Haxel and Schumann, 1955) for midlatitudes. In this study the integrated lifetime of the accumulation mode particles (0.6-2.5 µm) of 3 days in the marine boundary layer and 30 days above boundary layer, is also comparable previous modelled estimates such as: 10-15 days for the tropospheric column in Tropical regions (Balkanski et al, 1993) and of 2-12 days global mean lifetime at 1 km and 10-35 days at 8 km (Giorgi and Chameides, 1986).…”

“…These attach to aerosol particles and are removed with them during dry deposition and precipitation. Values of the order of 5 days were deduced for midlatitudes from the ratio of short-lived to long-lived radon daughters in surface air (Blifford et al, 1952;Haxel and Schumann 1955). As the decay of radon is essentially a gas to particle conversion process, the decay products attach primarily to a range of aerosol sizes within the accumulation mode and so it is particles within this size range that have an intergrated life- time of approximately 5 days.…”