石岛湾核电厂周边土壤理化特性及对放射性核素分配影响

发布时间：2018-01-04 01:15

本文关键词：石岛湾核电厂周边土壤理化特性及对放射性核素分配影响　出处：《中国农业科学院》2015年硕士论文　论文类型：学位论文

【摘要】：随着核技术的迅猛发展,核电厂为人类提供了电能的同时,原子核或放射性突发事件,大量放射性物质排放到土壤环境中,亟待探索核事故引起的关键放射性核素在土壤中的迁移规律,以便制定应对和修复策略,进一步完善核电厂对周围环境影响的评估方法。土壤水分动力学参数的对关键放射性核素迁移产生重要影响,但对这一方面研究研究很少。本文总结了国内外关于水动力学和核素分配系数已有的研究成果,以山东省荣成市石岛湾核电厂周边土壤景观为对象,在试验和分析的基础上,对核电厂周边土壤理化特性及对放射性核素的分配系数作了初步研究,旨在为提供建立评价。关键核素在土壤中的迁移模型。提供基础数据。已取得研究结果总结如下:1.针对石岛湾核电厂周边区域,选择4个方向(SW、W、NW和NNW)的横断面,分析比较了24个研究点的土壤颗粒组成和高程变化,同时比较了不同研究点耕作层(0~30cm)和深层(30~70cm)土壤容重、有机质、p H、电导率等理化特性,确定了研究区域理化特性的空间变异:各研究点的土壤有机质和电导率随着土壤深度增加呈减小。研究点海拔越高,土壤容重、有机质和电导率越小;研究区域土壤全部偏中性或酸性。2.基于石岛湾地区主要土壤类型-棕壤和风砂土,分别选择与之对应的大疃李家村和后海崖村作为研究点,将研究点土壤含水量和与之对应的基质势测定数据为基础,采用最小二乘法构建非线性方程组,利用Matlab软件求解,能够确定土壤水分特征曲线经验方程Van Genuchten模型各参数值。3.利用静态分析法。测定主要土壤类型的核素137Cs、60Co和85Sr的分配系数,并分析了影响分配系数的因素。结果显示,棕壤和风砂土剖面样品137Cs和60Co的Kd值较大,85Sr的Kd值较小。说明两种土类对137Cs和60Co吸附性大,对85Sr吸附性相对较小。通过相关性分析,棕壤研究点60Co的Kd与有机质和砂粒含量呈极显著负相关,土壤p H、电导率、粉粒含量呈极显著负相关(P0.01)。风砂土研究点,137Cs的分配系数与土壤p H和砂粒含量呈显著正相关,与土壤有机质呈负相关(P0.05)。
[Abstract]:With the rapid development of nuclear technology, nuclear power plants provide people with electricity, at the same time, atomic nuclei or radioactive emergencies, a large number of radioactive substances released into the soil environment. It is urgent to explore the migration rules of key radionuclides in soil caused by nuclear accidents in order to formulate coping and remediation strategies. Further improve the assessment method of nuclear power plant impact on the surrounding environment. Soil moisture dynamics parameters have an important impact on the key radionuclide migration. However, there is little research on this aspect. This paper summarizes the domestic and foreign research results on hydrodynamics and nuclide partition coefficient, taking the soil landscape around the Shidao Bay Nuclear Power Plant in Rongcheng City, Shandong Province as the object. Based on the experiment and analysis, the physical and chemical properties of the soil around the nuclear power plant and the partition coefficient of the radionuclides were preliminarily studied. The purpose of this study is to provide a model for evaluating the migration of key nuclides in the soil and to provide basic data. The results are summarized as follows: 1. For the surrounding area of the Shidao Bay Nuclear Power Plant, four directions are selected. The cross section of NW and NNW) was used to analyze and compare the soil particle composition and height change in 24 study sites. At the same time, the physical and chemical properties of soil bulk density, organic matter, pH and electrical conductivity were compared between the cultivated layer (30 cm) and deep layer (30 cm) in different research sites. The spatial variation of the physical and chemical properties of the study area was determined: the soil organic matter and conductivity decreased with the increase of soil depth. The higher the altitude, the smaller the soil bulk density and the lower the organic matter and electrical conductivity. Based on the main soil types of Shidao Bay, brown soil and wind-sand soil, the corresponding Datuan Lijia-Village and Houhaiya Village were selected as the research points. Based on the measured data of soil moisture content and the corresponding matrix potential, the nonlinear equations were constructed by least square method and solved by Matlab software. The parameters of Van Genuchten model can be determined by the empirical equation of soil moisture characteristic curve. Using static analysis method, 137Cs of radionuclides in the main soil types can be determined. The distribution coefficients of 60Co and 85Sr and the factors affecting the partition coefficients are analyzed. The results show that the values of KD of 137Cs and 60Co in brown soil and aeolian sandy soil sections are higher. The K _ d value of 85Sr is small, which indicates that the adsorption of 137Cs and 60Co by the two kinds of soils is large, and the adsorption of 85Sr is relatively small. The correlation analysis shows that the two kinds of soils have high adsorbability to 137Cs and 60Co. The K _ d of 60Co was negatively correlated with the content of organic matter and sand, and the soil pH, conductivity and silt content were significantly negative correlation (P _ (0.01)). The study point of wind-sand soil showed that the K _ d of 60Co was negatively correlated with the content of organic matter and sand. The partition coefficient of 137Cs was positively correlated with soil pH and sand content, and negatively correlated with soil organic matter.
【学位授予单位】：中国农业科学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM623;S151.9

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