近百年来淤成土断代的210Pbex蓄积-衰变模型

Based on physical processes of losses with runoff, accumulation and decay in soil after its deposition on the ground, a 210Pbex accumulation-decay model is established for the sediment soils, the model parameters are solved by using Fortran language and the Model interfaces are visualized. Sediment soil samples in profile are collected from glacial retreat land in Hailuogou, Mt.Gongga, debris flow terrace land and delta land with known sedimentation ages in Hunshuigou,Yinjiang County, Yunnan land of Yellow River, and 210Pbex activities of the samples are measured to obtained the nuclide reference inventories in the regions and the inventories of the sediment soils with the different ages. The established model is verified with the known sedimentation ages and the runoff loss coefficients of b and c also are derived from the ages. The convenient and reliable dating technique of sediment soils is developed first time in the world and it can be used for dating the sediment soils in last 100 years, particularly, before the remote sensing image appeared in the region.

基于210Pbex沉降到地面后的径流流失、土壤中蓄积和衰变的物理过程，建立淤成土的210Pbex蓄积-衰变模型，使用Fortran语言，求解模型参数并实现模型界面的可视化；在贡嘎山海螺沟冰川退缩迹地、云南盈江浑水沟泥石流迹地和黄河三角洲滩地等地，采集210Pbex本底值和已知泥沙淤积年代的淤成土土壤剖面样品，测定210Pbex含量，求算210Pbex本底值和不同年代淤成土的210Pbex面积活度；利用淤成土年限，验证210Pbex累积-衰变模型，求算模型中的径流流失系数b、c值。这一国内外首创的简便、可靠的淤成土断代技术，可应用于近百年来前卫星遥感图像时期的淤成土的断代。

基于210Pbex沉降到地面后的土壤中蓄积和衰变的物理过程，建立近百年来新淤成土的210 Pbex 蓄积-衰变模型。在贡嘎山海螺沟冰川退缩迹地、云南盈江浑水沟泥石流迹地和黄河三角洲滩地等地采集了已知泥沙淤积年代的淤成土土壤剖面样品，测定了粒度和210Pbex、137Cs比活度。建立了基于210Pbex 面积活度变化和基于表层土210Pbex活度变化的2个新淤成土断代的蓄积-衰变模型。云南盈江浑水沟已知成土年限的新泥石流迹地与沟口老泥石流冲积扇（本底剖面）表层土（3cm）的 210Pbex 比活度和淤成土成土时间拟合模型。通过黄河三角洲1929－1990年期间的四个不同成陆年限淤成土钻孔的137Cs、210Pbex活度和粒度的剖面深度分布资料分析，结合前人的毗邻海域研究成果，得出大气层核试验产生的放射性尘埃137Cs是可靠的断代示踪物，含137Cs的沉积物为1963年（或1954年）以来的沉积物；210Pbex是大气持续沉降的放射性尘埃, 不适用于间断快速沉积的入海口水下冲积扇的沉积物断代；也不适用于黄河陆地三角洲的沉积物断代。

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