Temporal distributions of radioactivity and⁸⁹Sr/⁹⁰Sr ratios during rainstorms

Abstract

Radionuciide concentrations for 89Sr, 90Sr, 144Ce, and 137Cs were sequentially sampled from two rainstorms to study fallout behavior as a function of rainfall rate and type of storm approximately 7 months after the eighth Chinese nuclear explosion of December 27, 1968. Great time variability in the 89Sr/90Sr ratio was found in conjunction with a well‐developed storm on July 21, but a nearly steady ratio was observed in a stratified stable‐type storm on August 14. Tapping of stratospheric air appeared to be the cause of the ratio changes. For both storms, a strong trend was found for concentrations of radioisotopes to decrease with increase in rainfall rate. Detailed discussions on meteorological factors, including a dilution effect, are given to interpret the experimental data.

The ratios of fission product pairs with similar half-lives in the atmosphere

“…After the first 2 months, it is more difficult to interpret the variations in the ratio. It appears that stratospheric tapping by intense thunderstorms may cause a dec{ease in the 9xY/89Sr ratio [Dingle, 1965;Noyce et al, 1971]. It is perhaps more likely that downward intrusions of stratospheric air masses into the troposphere in the Arkansas area via Danielsen 'tropopause folding mechanism' [Danielsen, 1964[Danielsen, , 1968Reed, 1955;Reed and Danielsen, 1959] The data of Thein et al [1968] seem to be in line with our recent data and can be interpreted in a similar manner.…”

Beryllium-7 atmospheric deposition and sediment inventories in the Neponset River estuary, Massachusetts, USA

“…Mid-latitude folding of the tropopause in spring has also been shown to enhance stratospheric-tropospheric exchange of 7 Be and increase 7 Be concentrations in the troposphere (Burchfield et al, 1983;Doering and Akber, 2008;Feely et al, 1989;Heikkila et al, 2008;Noyce et al, 1971). In addition, high-tapping thundershowers in the spring and summer months, can enhance stratospheric-tropospheric exchange and the washout of 7 Be via precipitation (Burchfield et al, 1983).…”

Environmental Chemistry of Beryllium-7

“…Maximum mixing between the stratosphere and the troposphere generally occurs in the spring of each year at mid-latitudes, and near-surface air at the middle latitudes generally has higher concentrations of 7 Be at this time (Feely et al 1989). Intense thunderstorms may also mix stratospheric air downward, thus increasing the amount of 7 Be available for scavenging by precipitation (Dingle 1965;Noyce et al 1971). Several authors have suggested that vertical mixing within the troposphere also governs the concentration of 7 Be in rain and near-earth surface air (Feely et al 1989;Baskaran 1995;Durana et al 1996;Dueñas et al 1999).…”