三峡库区<'7>Be沉降规律及其土壤侵蚀示踪研究
文献类型：学位论文
| 作者 | 史忠林
|
| 学位类别 | 硕士 |
| 答辩日期 | 2009 |
| 授予单位 | 中国科学院水利部成都山地灾害与环境研究所 |
| 授予地点 | 成都 |
| 导师 | 文安邦 |
| 关键词 | 三峡库区 |
| 其他题名 | A Study of 7Be Deposition and Its Application on Soil Erosion in Three Gorges Reservoir Region |
| 学位专业 | 自然地理学 |
| 中文摘要 | 三峡库区是我国土壤侵蚀最为严重的地区之一，然而该区侵蚀泥沙研究基础薄弱，手段有限，远不能满足实践的需要。大气沉降核素7Be由于其连续沉降且半衰期较短等特点而被用于示踪次降雨或较短时期土壤侵蚀。然而在我国有关7Be沉降的研究还很少，利用7Be示踪技术研究紫色土土壤侵蚀的工作尚未开展。 论文通过野外调查采样与室内分析相结合的方法，对天然放射性核素7Be的沉降规律、7Be在紫色土中的深度分布及其在土壤侵蚀调查中的应用进行了研究。主要结论如下： 1)采用“石英砂吸附法”和“FeCl3共沉淀法”测定7Be沉降通量结果表明，“石英砂吸附法”对7Be的吸附效率大于“FeCl3共沉淀法”，而且“石英砂吸附法”简单方便，可操作性强，特别适合于在野外实验条件不充分而又需要了解7Be沉降量的情况。 2)采用“石英砂吸附法”测得成都地区2008年8.30～12.31期间7Be沉降通量为0.78～8.50 Bqm-2d-1，以收集时间加权的平均值为3.19Bqm-2d-1；三峡库区2008年6.29～7.8期间7Be沉降通量为3.41 Bqm-2d-1；7Be沉降随季节变化明显，成都地区秋季明显高于冬季；7Be沉降通量不仅在季节间变异较大，在季节内的波动同样显著，但整体上表现出降雨量大则7Be沉降通量也大的趋势；成都地区和三峡库区地处同一纬度，两地降雨量也大致相等，因此7Be沉降通量差别不是很大。 3)通过对7Be大气沉降量的监测和土壤剖面中7Be含量的测定得出，紫色土对7Be的吸附效率较高，达到95%；研究区内紫色土平坦草地、橘园旱坡林地和荒坡地等三种不同类型土壤剖面中7Be的深度分布相似，7Be主要分布在土壤表层12mm的范围内，其中0～3mm范围内7Be含量最高，向下随深度增加大致呈指数递减，18mm以下基本不含7Be。 4)确定研究区域内7Be季节性本底值为375.02 Bqm-2；坡度为14°的紫色土缓坡撂荒地7Be面积活度介于183.97～423.72Bqm-2之间，坡长加权平均值为264.5 Bqm-2:确定紫色土7Be张驰质量深度为4.8kgm-2；采用Walling模型计算得到14°紫色土荒坡地平均土壤侵蚀速率为1.7 kgm-2 (17t ha-1)。 |
| 英文摘要 | Three Gorges reservoir areas are considered as one of the most seriously eroded regions in China. However, the sediment research foundation in these areas is weak, which makes it far from being able to meet the needs of practice. 7Be is a radionuclide that has been used to document short- term or event-based soil erosion because of its continuously deposition and short half-life. However, the research concerning 7Be atmospheric deposition is limited and the application of 7Be on tracing purple soil erosion has not yet carried out in our country. We used the means of field sampling and laboratory analysis to investigate 7Be deposition laws, 7Be depth distribution in purple soil and its application on soil erosion investigations. The main conclusions are as follows: 1) Measurements of 7Be deposition were carried out using the means of "Quartz sand adsorption" and "FeCl3 coprecipitation". The results show that 7Be adsorption efficiency of" Quartz sand adsorption " is higher than "FeCl3 coprecipitation" and "Quartz sand adsorption "is more convenient and easy to operate, especially for experiments in the field where experimental conditions are not sufficient and need to be aware of the situation of 7Be deposition. 2) 7Be deposition flux in Chengdu during 8.30~12.31, 2008 ranged from 0.78 to 8.50 Bqm-2d-1 with a time-weighted average of 3.19Bqm-2d-1; 7Be flux in Three Gorges Reservoir area was 3.41 Bqm-2d-1 in 6.29~7.8, 2008; 7Be deposition in Chengdu obviously changed with seasons, and it was significantly higher in fall than in winter; 7Be deposition fluxes not only have large seasonal variation but also significant fluctuations in the season. However, the overall performance indicates that 7Be deposition fluxes have a positive relationship with rainfall. 3) The atmospheric deposition of 7Be and its concentration in soil profiles was measured. It shows that the adsorption efficiency of purple soil to 7Be reached 95%; 7Be depth distribution in flat grassland, orangery dry woodland and barren slope is similar. 7Be are dominantly distributed in the surface soil of 12mm in depth. The highest 7Be content occurs in the surface horizon of 0~3mm in depth and it exponentially declines with depth. The soil horizon below 18mm in depth contains little 7Be. 4) 7Be seasonal reference inventory in the study area is 375.02 Bqm-2, and its activity ranged from 183.97 to 423.72 Bqm-2 in the slope with a gradient of 14 °. The length-weighted average is 264.5 Bqm-2. The 7Be relaxation mass depth is determined to be 4.8 kgm-2, and the average soil erosion rate in the slope is estimated to be 1.7 kgm-2 (17t ha-1) using Walling model. |
| 学科主题 | 土壤学 ; 水土保持学 |
| 语种 | 中文 |
| 公开日期 | 2010-09-19 |
| 源URL | [http://ir.imde.ac.cn/handle/131551/1996]  |
| 专题 | 成都山地灾害与环境研究所_成都山地所知识仓储（2009年以前） 成都山地灾害与环境研究所_山地表生过程与生态调控重点实验室 |
| 推荐引用方式 GB/T 7714 | 史忠林. 三峡库区<'7>Be沉降规律及其土壤侵蚀示踪研究[D]. 成都. 中国科学院水利部成都山地灾害与环境研究所. 2009. |
入库方式： OAI收割
来源：成都山地灾害与环境研究所
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