Behavior of radiostrontium in rain and air after the ninth Chinese Atmospheric Nuclear Test

Abstract

Strontium 89 and 90 were measured in rain water and air at Fayetteville, Arkansas (36øN, 94øW), for 9 months after the ninth Chinese atmospheric nuclear test. The s•Sr?øSr activity ratios showed behavior very similar to the pattern of variation observed after the eighth Chinese atmospheric test. Ratios of •Sr or •øSr activity in rains to activity in air samples were coniputed, and these scavenging ratios were found to vary widely, but those for •Sr tended to be higher than those for •øSr. These ratios did not have a welldefined relationship with time, amount of rainfall, or a number of meteorological parameters. The data, however, indicate that a consistent relationship between fallout and rainfall may be necessary for scavenging ratios to be meaningful and useful on a short-term basis. This relationship apparently does not exist in areas of high cumulative deposition of 9øSr, such as Fayetteville. E•gelmann [1970] has recently calculated the ratio of radioactive isotopes in rain and air samples (the so-called scavenging ratios) from a variety of sources and conditions. He recom-mended that these ratios be measured in the future, since such data may contribute to the understanding of precipitation processes and weather modification. Little is known concerning the relationship between the scavenging ratios and meteorological parameters, because of the difficulties involved in measuring the concentrations of radioactive isotopes in rain and in air simultaneously [e.g., Junge; 1963]. Shimo• [1970] reported that the monthly fl radioactivity from wet fallout in Budapest, when it was plotted against total precipitation for the month, gave two smooth curves if the yearly activity data were divided into summer and winter months. Gedeonov et al. [1970] found a simple proportionality between the concentrations of fission products in rain and air in Leningrad. These results seemed to indicate that relationships between the scavenging ratios and meteorological parameters could be established, once a sufficient amount'of data became available. In the present study the concentrations of 8øSr and øøSr were measured in rain and air samples collected at Fayetteville, Arkansas, for a period of 9 months following the ninth Chinese atmospheric nuclear explosion of September 29, 1969. EXPERIMENTAL TECI-I NIQUE Air samples were collected on the roof of the chemistry building at (he Universi(y of Arkansas by a Gelman 'Hurricane' air sampler, model 16003, which collected 140 m 3 of air per hour. Air was sampled for 1-or 2-day periods wi(h the use of cellulose-(ype IPC 1478 filters. The filters were relatively porous, and the flow ra(e did not drop by more (han • few percent during the collection period. Rain samples were ob-(ained from five co]lec(ors each 9.0 m • in area also located on the roof of (he chemistry building. Strontium was separa(ed from other fission produc(s as (he nitrate and radiochemically purified by the me(hod of Hodges [1963] with the addition of a calcium removal s(ep. The separ,•-(ion of s(romium from calcium w...

Strontium 90 fallout prediction

“…Various formulae relating fallout, precipitation rate, and concentration of tracer in air have been developed and tested against observations, [see, for example, Peirson et al, 1960;Pelletlet et al, 1965;Englemann, 1971;Noyce et al, 1973;de Bortoli and Gaglione, 1974;Krey and Toonkel, 1974;Slinn, 1977], but most have concentrated on fallout prediction over limited areas. We have extended the approach taken by Staley [1982], and Krey and Toonkel [1974] to construct a model that predicts monthly deposition in the northern hemisphere as a function of precipitation rate, latitude, and the zonally averaged concentration of 9øSr in surface air.…”