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很少有关于直接测定强度耕作侵蚀引起土壤退化过程的报道。我们的目的是确定应用137Cs和210Pbex直接定量评价耕作侵蚀对土壤有机质(SOM)坡面运移影响的可能性。我们在黄土高原陡坡耕地上进行了50次犁耕活动,并将与其相临的另一块陡坡耕地作为对照。在对照坡地不同坡位,137Cs浓度均匀分布于上部0～30cm土层,而210Pbex浓度在坡上部和坡中部随土层深度增加呈现线性递减,在坡下部呈指数函数递减。0～30cm土层中土壤有机质含量显著大于30cm深度以下土层,并在坡中部和坡下部呈现与210Pbex类似的土壤剖面分布特征。与对照坡地比较,50次犁耕活动导致坡上部、坡中部0～45cm土层的SOM含量分别降低了38%和47%,坡下部0～100cm土层中的SOM含量却提高了18%。坡上部土壤剖面中137Cs浓度的加权平均值从1.48Bq/kg降低到0.29Bq/kg,坡中部从2.53Bq/kg减少到0.33Bq/kg,坡下部从1.48Bq/kg提高到2.81Bq/kg。210Pbex浓度的剖面加权平均值在坡上部从27.71Bq/kg下降到6.15Bq/kg,在坡中部和坡下部分别从35.46Bq/kg和25.53Bq/kg降低到1.57Bq/kg和19.40Bq/kg。137Cs和210Pbex的剖面分布与SOM在p<0.001水平呈显著相关,相关系数R2值在对照坡地为0.81～0.86,在犁耕实验坡地为0.86～0.91。实验结果表明,环境放射性核素137Cs和210Pbex在黄
Few reports have been reported on the direct determination of soil degradation caused by intensive tillage erosion. Our goal is to determine the potential of using 137Cs and 210Pbex to directly and quantitatively assess the effects of tillage erosion on soil organic matter (SOM) slope transport. We carried out 50 plows on the steep slopes of the Loess Plateau and compared the other steep arable land with the other one. At different slope positions of the control slope, 137Cs concentrations were evenly distributed in the upper 0 ~ 30cm soil layer, while the 210Pbex concentration linearly decreased with the soil depth increasing in the upper part of the slope and the middle slope, exponentially decreasing in the lower slope. Soil organic matter content in 0 ~ 30cm soil layer was significantly greater than that in soil below 30cm depth, and the distribution of soil profile similar to 210Pbex appeared in the middle slope and lower slope. Compared with the control slopes, 50 times of plowing led to a decrease of SOM content by 38% and 47% in the upper part of the slope and the middle part of the slope from 0-45cm, respectively, and an increase of 18% in the SOM content of the 0-100cm layer in the lower part of the slope. The weighted average of 137Cs concentrations in the topsoil profile decreased from 1.48Bq / kg to 0.29Bq / kg, from 2.53Bq / kg to 0.33Bq / kg in the middle slope and from 1.48Bq / kg to 2.81Bq / kg in the bottom of the slope . The weighted average of the 210Pbex concentrations decreases from 27.71 Bq / kg to 6.15 Bq / kg in the upper part of the slope and from 35.46 Bq / kg and 25.53 Bq / kg to 1.57 Bq / kg and 19.40 Bq / kg in the mid-slope and lower part of the slope respectively . The cross sections of 137Cs and 210Pbex were significantly correlated with SOM at p <0.001. The correlation coefficient R2 was 0.81 ~ 0.86 in the control slope and 0.86 ~ 0.91 in the plowing experiment. The experimental results show that the environmental radionuclides 137Cs and 210Pbex in yellow