不同土地利用下放射性核素与土壤肥力因子关系研究

发布时间：2018-04-24 00:17

本文选题：放射性核素 + 营养元素　；参考：《南京师范大学》2015年硕士论文

【摘要】：南方红壤丘陵区地处亚热带,高强度降雨的侵蚀、淋溶以及剧烈的生物循环等对当地土壤质量影响显著,出现土壤质量退化现象。土壤质量退化导致土壤肥力逐渐下降、土壤结构发生改变。在由侵蚀引起的土壤肥力降低过程中,土壤有机质、土壤颗粒组成等变化明显。因此了解土壤肥力状况对于土地合理规划、有效管理及农业的可持续发展具有重要意义。鉴于放射性核素与土壤有机胶体、土壤颗粒等之间有较强吸附作用,探讨放射性核素与土壤肥力因子间相互关系,对定性评价土壤质量状况有重要理论意义。本文选取江西省余江县茶源山附近小流域作为研究对象,通过实地调查、样品理化分析及放射性核素测定等方法,对土壤放射性核素137Cs、210Pbex与土壤各项理化指标(TOC、TN、TP、土壤团聚体、土壤粒度)之间进行相关关系分析,得出以下结果：(1)土地利用类型对土壤剖面中137Cs和210pbex的含量分布规律和变化特点有显著影响,且两种放射性核素在土壤中的运移规律十分相似。主要表现为：非耕地中137Cs、210Pbex的含量在0-20cm深度范围内,随土壤深度增加呈现指数衰减分布趋势；农耕地中137Cs、210Pbex的含量在0～20cm深度范围内,随土壤深度的增加呈相对均一分布趋势。这说明137Cs和210pbex在土壤中的分布特征与运移规律具有明显相似性。(2)不同土地利用类型下营养元素分布及其与土壤放射性核素之间相关关系差异显著。主要表现为：①在不同土地利用类型下土壤0-20cm深度范围内,随土壤深度增加TOC、TN与两种放射性核素其含量分布趋势十分相似,TP与两种放射性核素其含量分布趋势差异较大。②总体上,TOC、TN含量与两种放射性核素含量之间相关关系显著,其中在非耕地中TOC、TN含量与两种放射性核素含量之间均有明显的相关关系,在农耕地中TOC、TN含量与两种放射性核素含量之间相关关系相对较弱。土壤1]P含量与两种放射性核素含量之间的相关关系较为复杂,在不同土地利用类型下其相关关系未出现一定规律性,但TP含量与pH值相关性较为显著。(3)不同土地利用类型下土壤机械组成及其与土壤放射性核素相关关系差异明显。主要表现为：①5-2mm粒级土壤水稳性团聚体含量与两种放射性核素含量之间相关关系明显,土壤水稳性团聚体平均重量直径与两种放射性核素含量之间也有显著相关关系。②对土壤颗粒粒径百分含量与放射性核素含量进行相关性研究发现,土壤砂粒百分含量与两种放射性核素含量之间有显著正相关关系,土壤粉粒百分含量与两种放射性核素含量之间呈现负相关关系,土壤黏粒百分含量与两种放射性核素含量之间呈现负相关关系。③不同土地利用类型下土壤颗粒粒径重量分形维数大小与两种放射性核素含量之间呈现明显反相关关系。
[Abstract]:The hilly region of red soil in southern China is located in the subtropical region. The erosion of high intensity rainfall, leaching and intense biological cycle have a significant effect on the soil quality, resulting in soil quality degradation. The degradation of soil quality leads to the decrease of soil fertility and the change of soil structure. In the process of soil fertility reduction caused by erosion, soil organic matter and soil particle composition changed obviously. Therefore, understanding soil fertility is of great significance for rational land planning, effective management and sustainable development of agriculture. In view of the strong adsorption between radionuclides and soil organic colloids and soil particles, it is of great theoretical significance to explore the relationship between radionuclides and soil fertility factors in the qualitative evaluation of soil quality. In this paper, a small watershed near Chayuanshan, Yujiang County, Jiangxi Province was selected as the research object. By means of field investigation, physical and chemical analysis of samples and determination of radionuclides, soil radionuclide 137Csf210Pbex and soil physicochemical indexes (TOC) TNTPand soil aggregates were studied. The correlation between soil granularity and soil size was analyzed, and the following results were obtained: (1) Land use type had a significant effect on the distribution and change characteristics of 137Cs and 210pbex in soil profile. The migration of two radionuclides in soil is very similar. The main results were as follows: the content of 137Csf210Pbex in non-cultivated land decreased exponentially with the increase of soil depth in the range of 0-20cm depth, and the content of 137Csf210Pbex in cultivated land was relatively uniform with the increase of soil depth in the range of 0~20cm depth. The results showed that the distribution and migration of 137Cs and 210pbex in soil were similar. 2) the distribution of nutrient elements and the correlation between nutrient elements and soil radionuclides in different land use types were significantly different. The main results are as follows: (1) in the range of soil 0-20cm depth under different land use types, With the increase of soil depth, the distribution trend of TOCN TN and two radionuclides is very similar. The distribution trend of TP and two radionuclides is quite different. 2. There is a significant correlation between TOC TN content and two kinds of radionuclides. 2 in general, there is a significant correlation between TOC TN content and two kinds of radionuclides. There was a significant correlation between TOC TN content and two kinds of radionuclides in non-cultivated land, but the correlation between TOC TN content and two radionuclides content was relatively weak in farming land. The correlation between soil P content and radionuclide content is complex, and there is no regularity in the correlation between soil P content and radionuclide content under different land use types. However, the correlation between TP content and pH value was significant. 3) soil mechanical composition and its correlation with soil radionuclides were significantly different under different land use types. The correlation between the content of water-stable aggregates and the contents of two kinds of radionuclides is obvious. There was also a significant correlation between the average weight diameter of soil water-stable aggregates and the contents of two radionuclides. There was a significant positive correlation between soil sand content and two kinds of radionuclides, and a negative correlation between soil silt content and two kinds of radionuclides. There was a negative correlation between soil clay content and two kinds of radionuclides. 3 there was a significant inverse correlation between the fractal dimension of soil particle size and the content of two radionuclides under different land use types.
【学位授予单位】：南京师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S158

【引证文献】