7Be fallout is predominantly distributed in the surface soil of 0-20 mm in depth. The highest 7Be content occurs in the surface horizon of 0-2 mm in depth and it exponentially declines with depth. The soil horizon below 20 mm in depth contains little 7Be. Our measurements show that there is a clear difference in 7Be depth distributions in purple soil between grass land and cultivated land in Yanting

Sichuan. 7Be contents in the surface horizon on grassland are higher and decline more rapidly with depth than those in cultivated land

because the cultivated soil is more porous and prone to infiltration of precipitation than the grass soil. 7Be seasonal reference inventories are 117.4 Bq ·m-2 in spring and 169.9 Bq · m-2 in autumn

respectively in Yanting. By comparison with the reported 7Be seasonal reference inventories in other regions in the world

the reference inventories in Yanting are quite lower. Probably this is attributed to the facts that the air moistures of the south-western currents from the low latitude area

which have a low 7Be concentrations

and the air moistures of local evaporation

which contains little 7Be

make great contributions to the precipitation in Sichuan Basin

and that the thick cloud layers and the cloudy climate in the Basin prevent cosmic ray penetration from producing 7Be nuclide.