KMS XINJIANG INSTITUTE OF ECOLOGY AND GEOGRAPHY，CAS
| 艾比湖流域沉积物元素地球化学特征及其揭示的环境信 | |
| 丁之勇 | |
| Subtype | 硕士 |
| Thesis Advisor | 吉力力·阿不都外力 |
| 2017-05-01 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 新疆乌鲁木齐 |
| Degree Discipline | 理学硕士 |
| Keyword | 艾比湖流域 沉积物 元素地球化学 环境演化历史 潜在生态风险 Ebinur Lake Basin Sediments Element Geochemical Environment Evolution History Potential Ecological Risk |
| Abstract | Soil is an important basis material for the survival of plants and animals on the earth. It is also an important resource for the development of human production. Element as an important component of soil, its natural content depends on the natural factors such as parent material, soil formation, topography, regional climate, biology and other natural factors. Lake sediments are faithful records of the natural environment evolution (climate, hydrology) and information of human activities in different periods. The elements in the soil of the river basin are imported into the lake under the action of erosion and transportation, and are deposited on the bottom of the lake. The changes in the records of its material sources, the degree of geochemical weathering and erosion, the intensity of human activities, regional climate change and the history of lake geochemical evolution are important indicators of regional environmental change. Therefore, in this study, physicochemical proxies (focus on elements) of sediment core in Ebinur Lake are studied, statistical analysis, the semi-variance function model, IDW method and potential ecological risk index method are using to analyze the elements spatial heterogeneity and influence factors of elements in topsoil are also analyzed; using enrichment factor correction method, sequential clustering analysis method to analyze the geochemical characteristics and the environment evolution history, heavy metal pollution history of watershed are also analyzed. This study, in order to give basic scientific guides for the coordinated development of the regional ecological environment and human society, a basic information of the regional environmental change and its response to human activities in Ebinur Lake basin. The main conclusions are listed as follows: （1） Descriptive statistics of element concentrations in topsoil showed: The average contents of Ba, Mn, V, Pb, Cr, Co, Ni, Cu in the topsoil of Ebinur Lake were lower than those of Xinjiang soil background value, while other elements of the average value are higher. The spatial distribution of the contents of elements Ca, Mg, Na, Sr, Ni and Cd shows the most obvious difference from medium to strong variability, while the other elements shows weak variability. The high value area of most elements is mainly located in the fields of farmland, traffic trunk, river and urban residential areas, which indicates that the distribution of surface elements in the study area is affected by human activities and local environment. （2） The environmental proxies of particle size, total organic carbon and elementsin Ebinur Lake shows that there are two obvious differences at the deep of 23cm (1960 AD): the content of each environmental proxy was lower and changed small before 1960; after 1960, the content suddenly increased and fluctuated significantly, especially heavy metals Co, Cr, Cu, Ni, Pb, V, Zn and so on. （3） The influence factors of elements in topsoil were analyzed by classical statistical and geostatistics analysis, which shows that elements Al, Fe, K, Ti, Ba, Be, Mn, V, Ti, Ba and so on have a medium to strong spatial autocorrelation and the spatial structure of the element P and the heavy metal elements Zn, Pb, Ni and Cu are more complicated due to random factors such as tillage fertilization, transportation, industrial and agricultural production. Elements Ca、Sr、Mg have a strong active geochemical characteristic, in addition to under the influence of regional soil parent material, and easily influenced by local factors lead to complicated spatial structure. Cd is a heavy metal element, however, it is divided into the same class with Ca, Sr and other activity chemical elements, which may be affected by the man-made industrial and agricultural activities, traffic and other anthropogenic resulting in large differences of the distribution and strong spatial variability in the study area, then there is no spatial autocorrelation at the sampling scale. Element Na shows a poor spatial structure due to the regional natural environment changes and the impact of man-made farming. （4） Elements in sediment core are divided into three assemblage: Fe, Mn, V, Ni, Li, Cr, K, Al, Co, P, Ti, Be, Pb, Cu, Ba and Zn are mainly derived from watershed terrestrial debris, and the content of those elements are mainly affected by the watershed erosion intensity. Among them, the changes of heavy metals Co, Cr, Cu, Ni, Pb, V, Zn and nutrient P were nearly different in the past 150 years. The ordered specimen cluster analysis method was applied to study the lake environmental changes base on the enrichment factors of heavy metals and P. The results show that the environmental evolution history nearly 150 years can divide into two distinct stages taking 23 cm (1960) as the boundary in the Ebinur Lake basin:Stage I. From 1875 to 1960 AD, at this stage the level of social development of the basin is low, human activities lead to less input of heavy metals, the basin environment is mainly affected by regional natural changes; Stage II. From 1960 ~ Present, with the increase of population, economic development, industrial and agricultural activities increased, especially agricultural water consumption increased, most of the heavy metal elements and P relative to the early have a more obvious increase. The second type of elements includes Mg and Na, mainly from the evaporation of salt crystals in lake water. Due to the development of oasis agriculture and the increase of irrigation water, the lake water level fluctuates violently under the influence of climate change and human activities which lead to the fluctuations Mg, Na and other elements. The third class elements include Ca and Sr, which are controlled by the weathering leaching of readily soluble elements in the watershed （5） The enrichment coefficient and the potential ecological risk assessment show that most of the heavy metal elements in the topsoil of the basin have been affected by human activities, and the enrichment of Cd is most obvious, its Er i value is up to 287.6 which means a highly potential ecological risk; followed by Ni and Cu, Ni Er i value of up to 25.7; Overall, 8 kinds of heavy metal elements in the topsoil comprehensive potential ecological risk (RI) average is 85.5 showing a slight ecological risk. And most of the high RI value areas are located in the main road, farmland and urban areas where human activities are relatively intensive. The accumulation of heavy metals in lake sediments core is lower than that in topsoil, although the accumulation of heavy metals has increased since 1960, but the total cumulative index and potential ecological risk are lower. The results showed the potential ecological risk of elements in sediment core followed the order: Ni(4.7)＞Pb(4.6)＞Cu(4.2) ＞Co(2.6)＞Cr(1.7)＝V(1.7)＞Zn(1.1), and the potential ecological risk of those heavy metals were slight. |
| Other Abstract | 土壤是地球生物生存的重要物质基础也是人类生产发展的重要资源，元素作为土壤的重要组成部分，其自然含量主要取决于母质、成土过程、地形、区域气候、生物等自然因素。湖泊沉积物是不同时期流域自然环境演化（气候、水文）和人类活动信息的忠实记录者，流域土壤中的元素在侵蚀、搬运等作用下汇入湖泊，沉积于湖底；沉积物中元素含量的变化记录了其物质来源、流域地球化学风化程度和侵蚀状况、人 类活动强度、区域气候变化以及湖泊自身地球化学演化历史等信息，是研究区域环境变化的重要指标。因此，本研究以艾比湖流域表土元素及艾比湖湖泊沉积物中的理化指标为研究对象（侧重元素），利用数理统计分析、半方差函数模型、IDW 插值方法和 Hakanson 潜在生态风险指数等方法分析了艾比湖流域表土元素的空间异质性和影响因素以及重金属污染现状；通过富集系数校正法、有序聚类分析法等分析沉积物中元素地球化学特征，揭示艾比湖流域环境演化规律。为深入了解区域环境变化和人类活动对艾比湖及其流域环境的影响提供基础资料，为区域生态环境和人类社会的可持续发展提供科学支持和理论依据。主要结论如下：（1）艾比湖流域表土中各元素含量与新疆土壤环境背景值相比，Ba、Mn、V、Pb、Cr、Co、Ni、Cu 等元素含量平均值均低于新疆表层土壤元素背景值，其它元素含量平均值均偏高；各元素含量的空间分布也呈现出较大差异性，元素 Ca、Mg、Na、Sr、Ni 和 Cd 最为明显，为中等至强变异性，其他元素均为弱变异性；大多数元素含量的高值区主要位于农田、交通干线、河流沿岸和城镇住宅等区域，表明研究区表土元素含量的分布受人为活动和区域环境等因素所致。（2）艾比湖湖泊沉积物中粒度、总有机碳和元素等环境代用指标均以 1960 年为界呈现出变化差异明显的两部分：1960 年以前各环境指标的含量较低且变化较小，1960 年以后含量突然增大且波动明显，尤其是重金属 Co、Cr、Cu、Ni、Pb、V、Zn等。（3）采用经典统计学和地统计学等方法分析表土元素的影响因素表明，Al、Fe、K、Ti、Ba、Be、Mn、V、Ti、Ba 等稳定性元素表现为中等或较强的空间自相关；元素 P 和重金属元素 Zn、Pb、Ni、Cu 由于受到局部随机因素如耕作施肥、交通、工农 II 艾比湖流域沉积物元素地球化学特征及其揭示的环境信息业生产等小尺度因素影响，空间结构较为复杂。Ca、Mg、Sr 在表生环境中地球化学活性较强，除受区域整体自然环境的控制外，还容易受人为耕作、径流等因素的影响导致空间结构性较差；Cd 为重金属元素，但在研究区内与 Ca、Sr 等化学性质活泼的元素分为一类，原因可能是人为工农业活动、交通等的作用较大，导致 Cd 在研究区的分布差异较大，空间变异性强，从而在采样尺度下不存在空间自相关。Na 元素由于受到区域自然环境变化和人为耕作的影响，空间结构性较差。（4）湖泊沉积物中元素 Fe、Mn、V、Ni、Li、Cr、K、Al、Co、P、Ti、Be、Pb、Cu、Ba 和 Zn 等主要来源于流域陆源碎屑物，受流域侵蚀强度等因素影响；其中，重金属 Co、Cr、Cu、Ni、Pb、V、Zn 和营养元素 P 近 150 年来变化差异较大，经地球化学校正后对这些元素进行有序聚类分析；结果表明，以 23 cm（1960 年）为界可将近 150 年来艾比湖流域环境演变历史分为差异明显的 2 个阶段：（I）1875～1960 年，在此阶段流域社会发展程度较低，人类活动导致的重金属输入少，流域环境主要受区域自然变化的影响；（II）1960～现在，随着人口的增加，经济发展工农业活动增强，尤其是农业用水量增加，大多数重金属元素和 P 相对于前期有较为明显的增加。第二类元素有 Mg和 Na，主要来源于湖泊水中蒸发盐类结晶；由于绿洲农业的发展，灌溉用水的增加，在气候变化和人类活动的共同影响下，湖泊水位发生了剧烈的波动，造成 Mg、Na 等元素的波动变化。第三类元素包括 Ca 和 Sr，受流域易溶元素风化淋溶作用控制。（5）富集系数和潜在生态风险评价表明，流域表土中大多数重金属元素已经受到人类活动较为明显的影响，尤其是 Cd 的富集最为明显，其 Eri 值最高达 287.6，具有极高的潜在生态风险；其次是 Ni 和 Cu，Ni 的 Eri 值最高达 25.7；总体来看，表土中8 种重金属元素综合潜在生态风险（RI）的平均值为 85.5，呈轻微生态风险，大部分RI 值的高值区域位于县际主干道旁、农田区和人类活动相对较为密集的城市区域。湖泊沉积物中重金属的污染程度比表土低，虽然从 1960 年以来各重金属的累积程度有所增加，但总的累积指数和潜在生态风险较低，Co、Cr、Cu、Ni、Pb、V、Zn 等七种重金属的潜在生态风险指数依次为 Ni(4.7)＞Pb(4.6)＞Cu(4.2)＞Co(2.6)＞Cr(1.7)＝V(1.7)＞Zn(1.1)，均为无生态风险状态。 |
| Subject Area | 自然地理学 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xjlas.org/handle/365004/14876 |
| Collection | 研究系统_荒漠环境研究室 |
| Affiliation | 中国科学院新疆生态与地理研究所 |
| First Author Affilication | 中国科学院新疆生态与地理研究所 |
| Recommended Citation GB/T 7714 | 丁之勇. 艾比湖流域沉积物元素地球化学特征及其揭示的环境信[D]. 新疆乌鲁木齐. 中国科学院大学,2017. |
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