Abstract: In the black soil region of Northeast China,soil and water loss is quite serious,but not fully investigated due to the lack of reliable methods. ¹³⁷Cs technology is a good one to study the medium and long term erosion and sedimentation rates and the spatial redistribution of soil.With this technology and the existing calibration models,this paper studied the redistribution patterns of black soil in a typical hillslope landform of Northeast China.The results showed that in the study area,the reference ¹³⁷Cs value was 2232.75 Bq穖^-2,intervenient the background values in the Yangtse River Delta and Loess Plateau;and the ¹³⁷Cs areal activity had a great differentiation in horizontal and vertical directions,being the lowest in the shoulder slope positions,which suggested that the summits and back slope positions suffered weak erosion,and some of the eroded soils were re deposited in foot slope and toe slope positions.The vertical distribution of ¹³⁷Cs in soil profile ranged from 20 cm on a shoulder slope to 80 cm on a toe slope position,indicating a significant erosion and deposition.Estimations with four existing calibration models showed that PM model underestimated while MBM₁ model overestimated the soil erosion rates very obviously,and both MBM₂ and MBM₃ gave similar and reasonable estimations.

Key words: Soil redistribution, Cesium-137 (¹³⁷Cs), Calibration models, Black soils, Northeast China