Contemporary evidence of radiological contamination of southeast Abai oblast, Kazakhstan, from nuclear weapons tests

Abstract Atmospheric tests of nuclear weapons were performed at the Semipalatinsk nuclear test site (SNTS) In Kazakhstan between 1949 and 1962 and at the Lop Nor nuclear test site (LNNTS) in China between 1964 and 1980. Archival reports suggest highly elevated total beta activities were detected in the superficial soil layer in southeast Abai oblast, Kazakhstan, in the days and weeks following tests performed at LNNTS. In this study, we reviewed contemporary evidence of contamination of southeast Abai oblast, including both previously published studies and newly acquired soil samples. Combined, these results provide little contemporary evidence of contamination of the study region by nuclear tests. Soil activities of 137 Cs in the study region are relatively low and within global average levels for the same latitude. The 240 Pu/ 239 Pu atomic ratio appears to be lower than the global average. This suggests regional contamination, however it is not possible to distinguish between LNNTS and SNTS as the potential source.