Professor Bushberg says removing the topsoil might make the land safe for use. But it depends on the depth of the radioactive material.
布希柏格教授说，移除表层土壤可以保证土地的使用安全，但这取决于放射性物质渗入的深度。
2
He ordered tons of fertile topsoil to cover the grounds to a depth of five feet and full-grown specimens of the plants were trucked up the mountain for planting.
他定购了成吨肥沃的表层土，覆盖地面达5英尺深，把这些植物长好的样品用卡车运到山上种植。
3
With the increasing depth of coal mining in China, there is an immediate need to improve the strength and durability of high performance concrete used in deep topsoil mine shafts.