Tao Zhou

The depth distributions of 137Cs and 210Pbex provide important information on the history of cultivated land and are essential for accurately calculating soil erosion rates. However, the depth distribution of 210Pbex in cultivated land is not always uniform. In this study, five sectioned core samples were collected along a downslope transect in cultivated land. The depth and spatial distribution characteristics of 137Cs and 210Pbex in cultivated land were investigated at the soil-profile scale, and soil redistribution rates were calculated. The depth distributions of 137Cs were generally uniform in cultivated soil. The two-layer uniform depth distribution of 210Pbex observed in this study differs from those reported in previous studies and may be related to a shift in tillage method. This non-uniform depth distribution of 210Pbex may lead to overestimation of soil erosion rates in cultivated land when existing 210Pbex conversion models are used. Moreover, differences in the spatial characteristics of the 137Cs and 210Pbex profile shapes on cultivated slopes reflect strong tillage erosion during the historical period. Soil erosion rates in cultivated land calculated using 137Cs and 210Pbex ranged from 239.83 to -78.12 t ha-1 yr-1 and from 45.53 to -143.98 t ha-1 yr-1, respectively, indicating a decreasing trend in soil erosion in recent years, although the rates calculated using 210Pbex were overestimated. In the future, the 210Pbex conversion model should be improved by incorporating the non-uniform depth distribution of 210Pbex.

The depth distributions of 137Cs and 210Pbex provide important information on the history of cultivated land and are essential for accurately calculating soil erosion rates. However, the depth distribution of 210Pbex in cultivated land is not always uniform. In this study, five sectioned core samples were collected along a downslope transect in cultivated land. The depth and spatial distribution characteristics of 137Cs and 210Pbex in cultivated land were investigated at the soil-profile scale, and soil redistribution rates were calculated. The depth distributions of 137Cs were generally uniform in cultivated soil. The two-layer uniform depth distribution of 210Pbex observed in this study differs from those reported in previous studies and may be related to a shift in tillage method. This non-uniform depth distribution of 210Pbex may lead to overestimation of soil erosion rates in cultivated land when existing 210Pbex conversion models are used. Moreover, differences in the spatial characteristics of the 137Cs and 210Pbex profile shapes on cultivated slopes reflect strong tillage erosion during the historical period. Soil erosion rates in cultivated land calculated using 137Cs and 210Pbex ranged from 239.83 to -78.12 t ha-1 yr-1 and from 45.53 to -143.98 t ha-1 yr-1, respectively, indicating a decreasing trend in soil erosion in recent years, although the rates calculated using 210Pbex were overestimated. In the future, the 210Pbex conversion model should be improved by incorporating the non-uniform depth distribution of 210Pbex.

The ecological restoration of mine dumps is challenging because of the loose soil structure, toxic heavy metal, and severe soil erosion at such sites. The impacts of native grass and polyacrylamide (PAM) on the soil sediment concentration, hydraulic properties, and heavy metals at mine dumps were investigated via scouring tests with a flow discharge of 90 L min⁻¹. In the initial stages of the tests, fluctuating decreasing trends in the soil sediment concentration, flow velocity, and flow Ni concentration were observed, while a fluctuating increasing trend was observed in the flow resistance f. After a period of adjustment, the steady‐state soil sediment concentrations, hydraulic properties, and Ni concentrations in the flow were attained. An increasing–decreasing trend for the V concentration and a decreasing–increasing trend for the Cu concentration in the flow were observed over time. In addition, Zn was not dissolved or transported by the overland flow. A significant correlation between the heavy metal concentration in the flow and soil sediment concentration was observed (p ≤ 0.01). Both native grass and PAM could effectively control soil loss and change hydraulic properties by increasing the surface roughness. The steady‐state flow velocity of B5 was 1.11–1.36 times higher than in the other treatments, while the steady‐state resistance f of B5 was 12.54–45.02% lower than in the other treatments. However, the native grass and PAM had different effects on the transport of heavy metals. The native grass could effectively reduce the mobility of V, while the PAM could reduce the mobility of Cu and V.