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探讨了137Cs与210Pbex在农耕地土壤深度分布过程的差异。基于137Cs与210Pbex的不同沉降过程,考虑到核素由犁耕层向犁底层的扩散,对农耕地土壤137Cs、210Pbex的深度分布过程进行了理论推导,并以杨凌符家庄麦田剖面的实测数据予以验证,同时讨论了实测符家庄麦田剖面137Cs、210Pbex深度分布的规律特征及其原因,以此阐明了137Cs与210Pbex在农耕地土壤深度分布过程的差异。137Cs源于大气核试爆,没有持续沉降补充,犁耕层和犁底层土壤137Cs深度分布一直处于随时间变化的非稳定态;而210Pbex是天然核素,存在大气沉降的持续补充,犁耕层和犁底层土壤210Pbex深度分布最终呈稳定态。农耕地土壤137Cs、210Pbex深度分布的实测值曲线与理论值曲线的差异,尤其210Pbex,可能与耕作深度的变化历史或土地利用(覆被)变化有关。
The differences of depth distribution of 137Cs and 210Pbex in farmland were discussed. Based on the different sedimentation processes of 137Cs and 210Pbex, taking into account the diffusion of nuclide from plow layer to plow bottom layer, the depth distribution of 137Cs and 210Pbex in farmland was theoretically derived. Based on the measured data of the Yangling Fujiazhuang wheat field profile The characteristics of the depth distribution of 137Cs and 210Pbex in the field of Fuji Zhuang were also discussed. The differences of depth distribution of 137Cs and 210Pbex in the soil were also discussed. The 137Cs originated from the atmospheric nuclear test explosion and did not continue subsidence supplementation. The depth distribution of 137Cs in plowed and plowed soils remained in an unsteady state over time. However, 210Pbex was a natural nuclide with continuous replenishment of atmospheric deposition. The 210Pbex depth profile of the bottom layer of the plow was finally stabilized. The difference between the measured and theoretical values of 137Cs and 210Pbex depth distributions in farmland soil, especially 210Pbex, may be related to the history of farming depth or the change of land use (cover).