Residence Times of Global Weapons Testing Fallout 237Np in a Grassland Soil Compared to 239+240Pu, 241A, 137Cs, Am

Abstract

The vertical distribution of weapons testing fallout 237Np has been determined in an undisturbed grassland soil (Alfisol). By using a compartmental model for multi-layered soils, the mean residence half-times of 237Np in each soil layer were calculated and compared with results on weapons fallout 239 + 240Pu, 241Am and 137Cs in the same soil. The results show that the mobility of 237Np was in most soil horizons either equal or slightly enhanced as compared to that of Pu, Am, and radiocesium.