Using 137Cs and 210Pbex to Investigate the Soil Erosion Moduli of the Sandy Area of Typical Grasslands in Northern China

Soil erosion results in land degradation and desertification in northern China. The Xilingol League of Inner Mongolia is an important part of the Two Barriers and Three Belts, and has been given the main function of a windbreak and sand-fixing belt of northern China. Accurate measuring of soil erosion moduli, analyzing the differences in soil erosion moduli across different periods and regions, are the basis for carrying out soil conservation and evaluating the effectiveness of ecological governance. Some radioisotopes are good environmental tracers because they are closely combined with the fine particles of the surface soil and are only affected by the mechanical movement of soil particles. In this paper, Taipusi Banner and Zhengxiangbai Banner, which are in the farming-pastoral ecotone in northern China, were selected as the study area. A regional reference inventory, that is, the activity of Cs-137 and Pb-210(ex) in the sample without any soil erosion, accumulation/deposition, or any kind of manual disturbances, as well as the soil erosion moduli, were determined by Cs-137 and Pb-210(ex) composite tracing technology and multiple lines of evidence. The results are as follows: (1) The regional Cs-137 reference inventory was 1928 Bq center dot m(-2), and the regional Pb-210(ex) reference inventory was 10,041 Bq center dot m(-2). (2) On a 50-year time scale, the soil erosion moduli in the study area ranged from 140 t center dot km(-2)center dot a(-1) to 1030 t center dot km(-2)center dot a(-1); on a 100-year scale, the soil erosion moduli in the study area ranged from 35 t center dot km(-2)center dot a(-1) to 2637 t center dot km(-2)center dot a(-1); the entire study area was in a lightly eroded state. (3) Compared with two periods before and after the 1970s, the southern parts (cultivated land and grassland) experienced an increasing trend in soil erosion moduli due to land reclamation, grassland grazing, and other activities. Due to weakening wind and increasing precipitation, soil erosion moduli in the northern parts (southern margin of the Hunshandake Sandy Land) slowed down. The study also discussed the uncertainty and application potential of isotope-tracing technology in sandy land of typical grasslands in northern China.

Automated summary

Soil erosion is a major cause of land degradation and desertification in northern China. This study used isotope tracing technology to measure the soil erosion modulus in the Xilingol League of Inner Mongolia and analyze the differences across different periods and regions. The results showed that the study area was in a lightly eroded state overall, but the southern parts experienced an increasing trend in soil erosion modulus due to land reclamation and grassland grazing, while the northern parts saw a slowdown in soil erosion modulus due to weakening wind and increasing precipitation.