基于模糊数学的太原盆地土壤地球化学环境质量评价

【作者】 张建东；

【导师】 赖健清；

【作者基本信息】 中南大学 ， 构造地质学， 2005， 硕士

【摘要】 本文研究太原盆地土壤生态地球化学特征,查明太原盆地54个指标的分布特征和统计学特征。在此基础上第一次利用模糊数学综合评价法系统地、全面地、综合地评价了太原盆地土壤质量的分布状况,利用评价结果对土壤进行了污染等级分类。 根据第一层次区域调查成果,通过对比盆地内深、表基础地球化学图,研究了太原盆地地球化学特征。研究表明,盆地腹部重金属Cu、Zn、Ni、Cd、Cr、As、U、Th的含量普遍升高,沿主干公路和城镇有Pb、Hg异常的形成;pH值在城市区域和汾河污灌区普遍性降低,向边山区方向pH值明显升高,表明盆地腹部汾河污灌区有明显的土壤酸性化发展趋势,太原盆地人类经济活动已经在很大程度上改变了地表地球化学特征。 通过太原盆地土壤元素总体特征的研究,发现深表地球化学特征的继承性是主要的,地表的改造也是明显的,有些元素(Cl、Cu、Ga、Hg、I、N、P、Pb、S、Se、C、Au、Cd)的表层富集已经非常严重,造成土壤肥力下降,农作物产量和质量恶化,通过食物链影响人类健康,破坏了太原盆地本来就比较脆弱的生态环境。 对54个元素指标作因子分析,在累积方差为90%的前提下,使用主成分分析得到23个因子。这样在解释各指标变化异常时可以着重讨论综合指标因子,通过综合指标的解释反演所有指标的变换规律,为土壤质量评价指标的选择提供一定的理论依据。 依据太原盆地土壤分布特征和本次研究工作目的,选择46个着眼因素对土壤进行综合评价,根据查瓦里茨基元素地球化学分类把46个因素分为七大类:造岩元素、铁族元素、亲岩稀有稀土元素、分散元素、溶剂元素、放射性元素、亲硫元素。在利用模糊数学评价法分别进行初步评价的基础上,最后进行太原盆地土壤质量综合评价和污染等级分类。认为太原盆地土壤质量综合评价的等级为:未污染的隶属度为0.27956,轻度污染的隶属度为0.5954,中度污染的隶属度为0.06245,重度污染的隶属度为0.04494,严重污染的隶属度为0.01765。轻度污染的隶属度最大,说明太原盆地土壤质量综合评价为轻度污染。更多还原

【Abstract】 In this dissertation, the eco-geochemical characteristics of the soil in Taiyuan Basin is studied to find out the distributive and statistical features of 54 elements and indexes, for the first time, to evaluate the soil quality and its distributive patterns systematically, completely, and synthetically by utilizing the Fuzzy Mathematics comprehensive evaluation method, and to classify the soil contaminative grades using the evaluative results.According to the first period regional investigation, the geochemical characteristics of Taiyuan Basin is studied by comparing geochemical diagrams of the soils between the deep layer and the superficial layer. The research shows that the contents of heavy metals such as Cu, Zn, Ni, Cd, Cr, As, U, and Th are enriched in the basin centre universally, and Pb and Hg abnormal along the main highroad and near towns. The value of pH reduces in the city and the sewerage irrigation region of Fen River universally, rises toward the side mountain direction obviously, which indicates that irrigation with sewerage have developed the soil acidification obviously, and the human economic activities of Taiyuan Basin have been changing the geochemical characteristics of the earth’s surface largely.Researching on the total characteristics of elements of the soil in Taiyuan Basin, we have discovered that the geochemical characteristics of the superficial inherit mainly from the deep layer, though there is obvious reformation. The surface layer has enriched some poisonous and harmful elements(Cl, Cu, Ga, Hg, I, N, P, Pb, S, Se, C, Au, and Cd), which caused the descent of soil fertility, deteriorated the cropper output and quality, influenced the human health by the food chain, and would destroy the originally fragile environment of Taiyuan Basin.Factor Analysis of 54 elements and indexes presents 23 factors under 90% of accumulative variance. When explained the various abnormality of each index, we can discussed the comprehensive index factors which deduced the changeable regulation of all indexes emphatically, thus provided the certain theory basis for the choice of thesoil quality evaluation indexes.For comprehensive evaluation, 46 evaluative indexes are chosen according to the soil distributive characteristics of the Taiyuan Basin and the recent research purpose, which are divided into 7 major types by the Chovalitsky’s geochemical classification of elements, that is petrogenetic elements, iron group elements, lithophile rare and rare earth elements, dispersed elements, solvent elements, radioelements, and sulfophilic elements. On the basis of preliminary evaluation with Fuzzy Mathematics method, we achieve the comprehensive evaluation of soil quality of Taiyuan Basin and classify the contaminative grades finally. It is suggested that the membership degree of unpollution, light-degree, moderate, heavy-degree and severe pollution are 0.27956, 0.5954, 0.06245, 0.04494, and 0.01765 respectively. The membership degree of light-degree pollution is the biggest, which implies that the soil quality of Taiyuan Basin is light-degree pollution as a whole.更多还原