长江安徽段江心洲土壤地球化学及重金属累积特征
发布时间：2018-07-16 23:50
【摘要】：江心洲作为流域环境的重要自然档案,对比不同形成原因和形成时间的江心洲上发育土壤的地球化学特征,不仅有助于认识江心洲土壤的形成发育,也有助于揭示河流地貌及流域环境的演变。本文以长江安徽段15个面积较大的江心洲为研究区,采集表层(0～20cm)和深层(150～180 cm)土壤样品,探讨研究区土壤地球化学特征,研究重金属元素含量的分布特征和来源,揭示其富集成因和迁移转化规律,并评价其潜在的生态风险。得到下列主要研究结论:1.江心洲经历不断消长、联并等过程,有些江心洲历史上变化很大,大部分洲体新于其初始形成时间。江心洲洲体的不断演变是江心洲土壤化学风化程度与江心洲初始形成时间不一致的主要原因。土壤化学风化指数(CIA)作为土壤发育程度的指标,可以指示所在洲体的形成时间,即CIA空间分布一定程度上可以指示江心洲演变过程。2.长江安徽段江心洲表层、深层土壤中大多数元素特别是表生环境中活动性弱、人为扰动影响小的元素含量间具有显著相关性,Cu、Pb、Zn、Hg和Cd等易受人为影响的元素在表层土壤出现明显富集。表层土壤中Cu、Pb、Zn、As、Hg等重金属平均含量均在我国土壤环境Ⅱ级质量标准限值内,分别有44%和8%的样品Cd含量超出了 Ⅱ级和Ⅲ级标准。3.不同江心洲之间以及同一江心洲内部土壤重金属含量的差异,主要与江心洲的成因及其发育演变过程有关,近期淤长的部分,土壤重金属元素含量通常比较高。4.研究区Cr、Ni、Cu、Zn、As和Pb等重金属元素随土壤发育呈累积趋势,而Cd和Hg受土壤发育程度影响较小。土壤重金属的富集主要与粒径效应、含钙矿物对Cd等元素的固定,以及受燃煤影响的大气沉降输入有关。粒度效应是影响研究区土壤重金属分布的主要因素,土壤粒度端元对研究区土壤Ni、Cu、Pb、Zn、As、Cd的贡献率均超过70%。钙以及受燃煤影响的大气沉降输入对上述重金属的影响已达到显著性水平,有机质和粒径效应对Hg的贡献率分别为57.8%和36.1%,土壤中有机物质的含量和成分的变化是决定Hg分布的主要控制因子。5.以长江沉积物背景值作为基线值进行的地累积指数评价结果表明,研究区土壤重金属富集程度为CdHgCuNiCrZnAsPb。潜在生态危害评价法显示,三号洲、凤凰洲重金属污染的生态风险最高,各江心洲出现不同程度的污染,且各采样点都有两种或更多的元素同时达到不同程度的污染水平,即表现为复合性的污染。
[Abstract]:Jiangxinzhou, as an important natural archives of watershed environment, not only helps to understand the formation and development of Jiangxinzhou soil, but also compares the geochemical characteristics of the developed soils on Jiangxinzhou with different formation reasons and time. It is also helpful to reveal the evolution of river geomorphology and watershed environment. In this paper, 15 large Jiangxinzhou in Anhui section of the Yangtze River are taken as the study area. The soil samples of surface (0~20cm) and deep layer (150m ~ 180cm) are collected, and the geochemical characteristics of soil and the distribution characteristics and sources of heavy metal contents in the study area are discussed. The enrichment causes, migration and transformation laws were revealed and its potential ecological risks were evaluated. The main conclusions are as follows: 1. Jiangxinzhou has experienced continuous growth and decline, joint merger and other processes. Some Jiangxinzhou has changed greatly in history, and most of the continental bodies were newly formed at the time of its initial formation. The continuous evolution of Jiangxinzhou body is the main reason why the soil chemical weathering degree of Jiangxinzhou is inconsistent with the initial formation time of Jiangxinzhou. Soil chemical weathering index (CIA), as an indicator of soil development, can indicate the formation time of the continental body, that is, the CIA spatial distribution can indicate the evolution process of Jiangxinzhou to some extent. In the surface layer of Jiangxinzhou in the Anhui section of the Yangtze River, the activity of most elements in the deep soil, especially in the supergene environment, is weak. There was a significant correlation between the contents of elements with small disturbance, such as CuPbHG, ZnHG, CD and so on, which were obviously enriched in the topsoil. The average contents of heavy metals such as Cu PbPb, ZnN, AsHg and so on in the surface soil were within the limit of grade 鈪，
本文编号：2128107
[Abstract]:Jiangxinzhou, as an important natural archives of watershed environment, not only helps to understand the formation and development of Jiangxinzhou soil, but also compares the geochemical characteristics of the developed soils on Jiangxinzhou with different formation reasons and time. It is also helpful to reveal the evolution of river geomorphology and watershed environment. In this paper, 15 large Jiangxinzhou in Anhui section of the Yangtze River are taken as the study area. The soil samples of surface (0~20cm) and deep layer (150m ~ 180cm) are collected, and the geochemical characteristics of soil and the distribution characteristics and sources of heavy metal contents in the study area are discussed. The enrichment causes, migration and transformation laws were revealed and its potential ecological risks were evaluated. The main conclusions are as follows: 1. Jiangxinzhou has experienced continuous growth and decline, joint merger and other processes. Some Jiangxinzhou has changed greatly in history, and most of the continental bodies were newly formed at the time of its initial formation. The continuous evolution of Jiangxinzhou body is the main reason why the soil chemical weathering degree of Jiangxinzhou is inconsistent with the initial formation time of Jiangxinzhou. Soil chemical weathering index (CIA), as an indicator of soil development, can indicate the formation time of the continental body, that is, the CIA spatial distribution can indicate the evolution process of Jiangxinzhou to some extent. In the surface layer of Jiangxinzhou in the Anhui section of the Yangtze River, the activity of most elements in the deep soil, especially in the supergene environment, is weak. There was a significant correlation between the contents of elements with small disturbance, such as CuPbHG, ZnHG, CD and so on, which were obviously enriched in the topsoil. The average contents of heavy metals such as Cu PbPb, ZnN, AsHg and so on in the surface soil were within the limit of grade 鈪，
本文编号：2128107
本文链接：https://www.wllwen.com/shengtaihuanjingbaohulunwen/2128107.html
