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

Due to the atmospheric nuclear weapon tests carried out, terrestrial environments have been extensively contaminated by global fallout of plutonium (Pu) worldwide. The ^249+240Pu 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+240Pu inventories and possible controlling factors. The aim of this work was to derive an empirical model of ^239+240Pu inventory based on currently available ^239+240Pu data, precipitation and latitude. The results show that, in general, the latitudinal distribution of ^239+240Pu inventory was consistent with the UNSCEAR reports. However, the ^239+240Pu 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+240Pu inventories and annual precipitation and latitude. An empirical formula was therefore developed to estimate ^239+240Pu inventories in soils based on latitude and precipitation data. However, future research may require more data of measured ^239+240Pu inventories in soil profiles that can be used to compare, validate and improve upon the accuracy of the inferred empirical equation. [ABSTRACT FROM AUTHOR]