Quantitative assessment of the spatial distribution of 239+240Pu inventory derived from global fallout in soils from Asia and Europe

Abstract

Due to the atmospheric nuclear weapon tests carried out, terrestrial environments have been extensively contaminated by global fallout of plutonium (Pu) worldwide. The 249+240 Pu inventories in soil profiles from undisturbed and flat forest or grasslands (reference sites) mainly from Europe and Asia are considered as important background for evaluating soil erosion. Thus, we conducted a literature survey over an area extending from 2.6°W to 148.9°E and from 53.2°S to 76.6°N, with the purpose of analyzing the spatial distribution of 239+240 Pu inventories and possible controlling factors. The aim of this work was to derive an empirical model of 239+240 Pu inventory based on currently available 239+240 Pu data, precipitation and latitude. The results show that, in general, the latitudinal distribution of 239+240 Pu inventory was consistent with the UNSCEAR reports. However, the 239+240 Pu inventories are higher than the UNSCEAR data, especially in the Northern Hemisphere. In addition, close relationships (at the 0.01 significance level) were identified between 239+240 Pu inventories and annual precipitation and latitude. An empirical formula was therefore developed to estimate 239+240 Pu inventories in soils based on latitude and precipitation data. However, future research may require more data of measured 239+240 Pu inventories in soil profiles that can be used to compare, validate and improve upon the accuracy of the inferred empirical equation.

First application of plutonium in soil erosion research on terraces

“…The mean inventories of 239+240 Pu and 137 Cs in Longji Rice Terraces were 100.40 and 1530.24 Bq/m 2 , respectively. The mean inventory of 239+240 Pu was higher than the result (63 Bq/m 2 ) of forest soil in Guiyang of Guizhou [42] but within the range (36 -410 Bq/m 2 ) in the 20 -30°N band summarized by Cao et al [63]. The mean inventory of 137 Cs was higher than that previous studies in Kaiyuan [61] and Libo [62], but within the range (414.42 -3140.88 Bq/m 2 , decay-corrected to 2021) in the 20-30°N band summarized by Tagami et al [64].…”