胶东山区不同土地利用方式对土壤重金属分布的影响研究

发布时间：2018-09-03 06:46

【摘要】：土地利用作为人类利用土地各种活动的综合反映,是影响土壤质量变化最普遍、最直接、最深刻的因素。土壤重金属含量是评价农产品产地环境质量的重要指标,准确分析土地利用变化对于土壤重金属污染的影响具有重要意义。栖霞市作为我国苹果主产区,了解不同土地利用方式对于土壤重金属的分布影响,能够确保农产品安全,保证生态安全和人类健康。本文以栖霞市1987年、1992年、1997年、2002、2007年五期遥感影像作为数据源,结合研究区域的统计资料、环境年报等资料,同时进行野外调查、实地走访等,获得研究区域近20年的土地利用变化数据,在GIS平台对上栖霞市土地利用动态变化进行分析。由于土壤重金属的累积特性,以2007年栖霞市土壤重金属调查数据为数据源,分析栖霞市不同土地利用方式及利用时间对土壤重金属分布的影响。得出的结论主要有:(1)1987-2007年间,栖霞市园地和草地面积先增后减,耕地和未利用地面积有所减少,林地和建设用地面积持续增加,其中建设用地变化速度最快。耕地、未利用地和建设用地土地利用类型间的空间转换比较频繁,耕地、未利用地、园地用地面积变化幅度大于林地、建设用地和草地用地面积变化幅度。(2)表层土壤不同重金属元素含量差异较大,Cd、Cu、Hg、Ni的平均含量较山东省土壤元素背景值较高,其中Cu含量平均值超过山东省背景值达2.25倍,Cr、Pb、Zn的含量平均值稍高于其背景值。深层土壤重金属含量平均值略高于山东省深层土壤元素背景值,表明栖霞市深层土壤也不同程度的受到人类活动的干扰。Cu、Ni、Zn在植物体内具有非常重要的生理作用,三种重金属在草地、林地、园地和耕地中均具有较高的累积量,研究区采用集约化的生产模式,三种重金属对于集约化生产模式下的植物生长稳定性及增产具有重要意义。而As、Cd、Cr、Hg和Pb在不同地类中的累积量较低。不同地类中对不同土地利用方式下土壤重金属的垂直累积统计值分析,各元素在园地和建设用地中具有较高的垂直累积率。栖霞市作为苹果主产区,在果园管理过程中,对于化肥及农药的使用使土壤中重金属含量增加,而园地特殊的管理方式,使得土壤重金属累积效果显著,而建设用地是受人类活动影响最强烈的区域,人类对于土壤构造的机械破坏促进了土壤重金属的垂直迁移。未利用地、林地作为人类影响较弱的斑块,各元素的垂直迁移率也较低,综合分析发现,不同土地利用方式影响土壤重金属垂直迁移率强弱为:建设用地园地耕地草地林地未利用地。整体土壤重金属元素含量均处于国家环境质量二级标准以内,有利于保证当地生态环境的稳定性。(3)对栖霞市重金属进行人为源、自然源辨识。利用多元统计分析方法结果表明:栖霞市土壤中Cd、Pb、Zn、Ni、Hg和Cu都倾向于人为导致,而As和Cr则主要来源于成土母质,这与人们一般认为的观点一致。耕地、园地和建设用地是受到人类活动影响较大的区域,人类生产生活产生的废弃物以及农业生产过程中的土壤肥料等都对土壤重金属累积产生影响,在这三种土地利用类型上,Cd、Pb、Zn、Ni、Hg和Cu都表现出了较高的累积。As和Cr在不同土地利用方式上未出现累积现象。(4)不同土地利用方式对土壤重金属水平分布的影响研究发现,人类活动影响的强弱直接决定了土壤中重金属的含量。土壤重金属的水平分布含量状况表现出:建设用地园地耕地草地林地未利用地。通过对不同土地利用类型下土壤重金属垂向分布特征可以发现,Cu、Cd和Hg在不同土地利用方式上都保持着较高的累积。Cu、Zn和Ni作为植物生长必需的微量元素,保持在正常的含量范围内。结合源汇理论,将耕地、建设用地和园地作为“源类型”,这类区域对于土壤重金属的累积具有一定的促进作用,人类活动的影响使得这部分区域成为土壤重金属累积的重点区域。将草地、林地和未利用地作为“汇类型”,这类区域受到人类活动的影响较小,同时自身具有一定的自净能力,能够有效的吸附土壤中的重金属元素。(5)对栖霞市土壤环境质量进行单因子污染指数和综合污染指数评价,依据评价标准将栖霞市划分为清洁区、优先保护区、安全利用区、严格管控区和风险限制区,全域范围有95.9%处于轻微污染范围内,少数区域达到风险限制区。根据单因子污染指数可以发现,Cu和Hg积累程度相对较高,尤其是Hg,但整体处于国家环境质量二级标准之内,在可控的范围内。结合综合污染指数可以发现,重金属污染具有明显的片状分布。
[Abstract]:Land use, as a comprehensive reflection of land use activities, is the most common, direct and profound factor affecting soil quality change. Heavy metal content in soil is an important index to evaluate the environmental quality of agricultural products producing areas. It is of great significance to accurately analyze the impact of land use change on soil heavy metal pollution. As the main apple producing area in China, understanding the effects of different land use patterns on the distribution of heavy metals in soil can ensure the safety of agricultural products, ecological security and human health. The data of land use change in the past 20 years were obtained through field investigation and field visits, and the dynamic changes of land use in Shangqixia City were analyzed on the platform of GIS. The main conclusions are as follows: (1) From 1987 to 2007, the area of garden land and grassland increased first and then decreased, the area of cultivated land and unused land decreased, the area of forest land and construction land increased continuously, and the change speed of construction land was the fastest. (2) The contents of different heavy metals in surface soil varied greatly, and the average contents of Cd, Cu, Hg and Ni were higher than the background values of soil elements in Shandong Province, in which the average content of Cu was higher than that in the mountains. The background value of the eastern province is 2.25 times, and the average contents of Cr, Pb and Zn are slightly higher than the background value. The average contents of heavy metals in the deep soil are slightly higher than those in the deep soil of Shandong Province, indicating that the deep soil in Qixia city is also disturbed by human activities to varying degrees. Cu, Ni and Zn have very important physiological functions in plants, and three kinds of heavy gold. The accumulation of As, Cd, Cr, Hg and Pb in grassland, woodland, garden and arable land is high. The intensive production mode is adopted in the study area. The three heavy metals are of great importance to plant growth stability and yield increase under the intensive production mode. According to the analysis of the vertical accumulation statistics of heavy metals in soil, the vertical accumulation rate of each element in garden and construction land was higher. Qixia city, as the main apple producing area, increased the content of heavy metals in soil by using chemical fertilizers and pesticides in the process of orchard management. The effect is remarkable, but the construction land is the most strongly affected area by human activities, and the mechanical destruction of soil structure promotes the vertical migration of heavy metals in the soil. Vertical mobility of metals is as follows: unused land of construction land, garden land, grassland and woodland. The content of heavy metals in the whole soil is within the second level of national environmental quality standards, which is conducive to ensuring the stability of the local ecological environment. (3) Identification of heavy metals from human and natural sources in Qixia city. The results showed that Cd, Pb, Zn, Ni, Hg and Cu in the soil of Qixia City tended to be artificially induced, while As and Cr were mainly derived from the parent material of soil formation, which was consistent with the general view. Cd, Pb, Zn, Ni, Hg and Cu all showed higher accumulation in the three land use types. As and Cr did not accumulate in different land use patterns. (4) The effect of different land use patterns on soil heavy metal level distribution was found to be direct by human activities. The content of heavy metals in soil was determined. The horizontal distribution of heavy metals in soil was shown as follows: unused land in construction land, garden land, grassland and woodland. According to the theory of source and sink, cultivated land, construction land and garden land are regarded as "source types", which can promote the accumulation of heavy metals in soil. The influence of human activities makes this region become the key area of heavy metals accumulation in soil. The grassland, woodland and unused land are regarded as sink types, which are less affected by human activities, and have certain self-purification ability, and can effectively absorb heavy metals in soil. (5) The single factor pollution index and comprehensive pollution index of soil environmental quality in Qixia city are evaluated according to the evaluation criteria. According to the single factor pollution index, the accumulation of Cu and Hg is relatively high, especially Hg, but the whole area is in the second national environmental quality. It is found that the heavy metal pollution has obvious flake distribution within the grade standard and within the controllable range.
【学位授予单位】：山东农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X53;F301.2

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