我国红壤地区土壤中137Cs分布特征及侵蚀示踪研究

The old paddy farmland was identified as the 137Cs reference site with a 137Cs inventory of 1135 Bq m-2, 1113 Bq m-2, 1298 Bq m-2, and 1068 Bq m-2 for four typical study areas located at Liujiazhan and Liuken in Yujiang county of Jiangxi Province, Tongcheng county of Hubei Province, and Longyou county of Zhejiang Province, respectively, developed from Quaternary Red Clay, Red Sandstone, Granite and Argillaceous Shale, respectively. The spatial variability of 137Cs reference inventories across the eastern part of Yanshan county is due to the systematic spatial variability reflecting the increasing trend of rainfall amount from the north to south across Yanshan, as represented by the positive relationship between rainfall amount and 137Cs reference inventory. .The 137Cs depth distribution patterns in soils, developed from different parent materials and under different land uses, were described in this thesis. For uncultivated soils developed from most selected parent materials, soil 137Cs depth distributions show not only exponential patterns, but also peak pattern, primarily depending on the its water penetration ability, the soil particle size composition and its depth distribution, sometimes, to some extent, being related to the site topographical position and soil organic matter content. 137Cs shows uniform distribution in the plough layer of paddy soils developed from Quaternary Red Clay, Red Sandstone, and Argillaceous Shale. However, within the plough layer of dry terrace farmland developed from Quaternary Red Clay, dry farmland on the flat crest developed from Red Sandstone, dry and paddy farmland developed from Granite, 137Cs exhibits basically uniform distribution, except that 137Cs concentration of the surface 2cm (for Quaternary Red Clay) or 5cm(for Red Sandstone and Granite), are slightly lower than that of soil below 2 or 5cm within the plough layer. Notably, 137Cs activity of surface several centimeters soil developed from Quaternary Red Clay and Red Sandstone is significantly lower than that of soil below several centimeters within the plough layer. These observation demonstrated the occurrence of significant particle size selectivity of erosion process. .It was also revealed that the 137Cs downward penetration behavior mainly depended on the depth distribution of particle size composition, show no significant relationship with soil organic matter. Moreover, the particle size selectivity effect was more significant in the cultivated soil than in the uncultivated soil..The different spatial characteristics of water-induced erosion on soils developed from different parent materials were obtained quantitatively using 137Cs technique. The analysis of soil 137Cs and nutrition content also demonstration negative relationship between the spatial characteristics of soil erosion and that of nutrition levels, with different situations in soils developed from different parent materials..

我国红壤地区为土壤侵蚀的重灾区。本项工作利用137Cs技术研究本地区的土壤侵蚀速率及氲匦巍⑼林省⒅脖弧⒏髯纯龊推虻墓叵担晃岣吖兰剖莸木龋氐阊芯客寥乐?37Cs的分布特征和年富集层的特征，建立适合本区的估计土壤侵蚀速率的定量模型。研究结果可对控制和彻底防治本区水土流失提供可靠数据，工作具有重要的理论意义和实用价值。