关键词: 同位素示踪, 土壤有机质, 全氮, 全磷

Abstract: Soil erosion is one of the most serious environmental problems in China, which has brought  huge impact on ecology and human development. Owing to the close correlation between 137Cs redistribution in soil and soil erosion migration, this paper took it as a tracer and studied the soil erosion and accumulation to calculate the soil erosion rate, space distribution, and also the spatial distribution of soil erosion and spatial distribution of soil migration. This paper adopted 137Cs tracer technology to study soil erosion in Tong Mountain area, and further explored the effects of soil erosion on soil nutrients. The background value of 137Cs in the study area was 1 732.48 Bq/m2. With the increase of soil depth, the mass concentration of 137Cs decreased logarithmically. The 137Cs content in the study area ranged from 787.62 Bq/m2 to 2 380.96 Bq/m2. Soil deposit and soil erosion occurred in the study area at the same time. The 137Cs content in forest land was the highest, followed by bamboo grove and tea plantation. The distribution of TN, TP and SOC in different types of land was also different. There was a very significant linear positive correlation between SOC and 137Cs, but there was no significant correlation between 137Cs and TN and TP. Erosion had the most significant effect on soil surface. Compared with the background area, the 137Cs and SOC at soil surface layer (0~5 cm) both in the erosion and deposition areas had obvious losses, reaching 31%, 17% and 45%, 29%, respectively. The results showed that the soil erosion resistance of woodland was stronger than that of tea garden and bamboo forest. In the process of soil erosion, distribution of SOC, TN and TP would be influenced by soil redistribution with different degrees. Influence on SOC was the strongest. The effect of soil erosion at soil surface layer was the most obvious, the upper soil layer was usually the most concentrated place for nutrient. Therefore, soil erosion would cause soil nutrients loss and pollute down stream and rivers. Many agricultural and environmental problems were worthy of attention.

Key words: isotopic trace, soil organic matter, total nitrogen, total phosphorus