风蚀区137Cs与有机质剖面分布及其关系——以新疆准东地区为例

Distribution of 137Cs and Soil Organic Matter Contents in Wind Erosion Zone: A Case Study in the East Junggar Basin,Xinjiang

通过对新疆准东地区沙地、裸地、戈壁、耕地和草地进行土样采集,分析了土壤137Cs和有机质的分布特征,估算各土地利用类型的土壤侵蚀量并对其进行验证,同时探讨137Cs与有机质之间的关系。结果发现：非耕地土壤137Cs基本分布在地表15 cm以内,耕地土壤137Cs主要分布在犁耕层;非耕地137Cs均随土壤深度的增加呈下降趋势,耕地呈现均匀分布;草地土壤有机质随土壤深度增加呈减少趋势,戈壁和裸地有机质含量变化不明显,耕地有机质含量呈均匀状态分布;各土地利用类型下137Cs含量总体表现为：草地〉固定沙地〉戈壁〉耕地〉裸地〉半固定沙地,而有机质含量呈现为：草地和耕地〉戈壁〉固定沙地〉半固定沙地和裸地。各样点利用137Cs示踪法估算土壤侵蚀速率之间的差异,137Cs示踪技术在风蚀地区测定的土壤风蚀并不可靠。准东土壤137Cs与有机质呈现为弱相关或不相关,在准东风蚀区用137Cs监测土壤有机质动态的效果并不明显。

The effect of SOC caused by soil erosion has become as a focus in the study of carbon cycle in arid area. The relationship between 137Cs and soil organic carbon can be used to monitor SOM and to provide the references for preventing and controlling nutrient loss in arid area. Soil samples were collected at 2 cm depth interval from sandy land,bare land,Gobi desert,steppe and arable land in the east Junggar Basin,Xinjiang. The SOM and 137Cs of soil samples were measured,and the 137Cs tracer method was used to estimate the soil erosion rates of five different land use types. Synchronously,the relationship between SOM and soil 137Cs in different land use types was discussed. The results showed that 137Cs was basically distributed within 15 cm of non-arable soil depth,and mainly in plough layer of cultivated land. The 137Cs was decreased with the increase of soil depth in non-cultivated land,and there was a uniform distribution in the farmland. The SOM of steppe was in a decrease trend with the increase of soil depth. The change of organic matter content in Gobi desert and bare land was not significant,and the organic matter content in cultivated land was distributed uniformly. The total 137Cs content was in an order of steppe fixed sandy land Gobi desert cultivated land bare land semi-fixed sandy land,and the organic matter content was in an order of steppe and cultivated land Gobi desert fixed sandy land semi-fixed sandy land and bare land. The soil erosion rates estimated by 137Cs tracer method were quite different from the different sampling sites.The differences between the values of wind erosion determined by the 137Cs tracer technique and the actually measured results were significant. There was a weak or no correlation between soil 137Cs and organic matter content in the east Junggar Basin.