Knowledge Resource Center for Ecological Environment in Arid Area
| 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 | |
| 其他题名 | Characteristics of element geochemical and its environmental information inferred from sediments in Ebinur Lake basin, Northwest China |
| 丁之勇 | |
| 出版年 | 2017 |
| 学位类型 | 硕士 |
| 导师 | 叶柏生 ; 丁永建 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 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。 |
| 英文摘要 | The soil is an important basis material for life on earth and an important resource for human being, element as an important component of the soil, its natural content mainly depends on the parent material, soil forming process, topography, climate, biology and other natural factors. The lake sediment is the faithful recorder, it record the natural environment evolution (climate and hydrology change), anthropogenic activities information, elements in watershed are flow into lakes through regional erosion, transport action of rivers, and then deposited in lake. Elements in lake sediment core recorded the sources, geochemical weathering degrees in basin and its erosion information, and its recorded the anthropogenic activities history, regional environment change and geochemical evolution history of lakes, it is an important proxy to study the region environment 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 elements (Ba, Mn, V, Pb, Cr, Co, Ni, Cu) contents are lower than their value of background in Xinjiang, others elements concentrations are higher. The spatial distribution of elements content is also showing big variability, especially elements Ca, Mg, Na, Sr, Ni, Cd showed moderate to strong variability, others show low variability. Most of elements show higher value in farmland, highway side, rivers side and regions of residential, that indicated elements value in Ebinur Lake Basin are influenced by anthropogenic activities and regional environment.② The environment proxy of grain size, TOC and elements show an obviously difference at deep of 23 cm (1960 AD) in sediment core from Ebinur Lake Basin: there had a low value and variability before 1960 AD, but then all proxies show larger change and higher value than after 1960 AD, especially heavy metal Co, Cr, Cu、Ni, Pb, V, Zn.③ The geostatistics analysis indicated, all those 20 elements exist spatial correlation in the sampling scale; among them, elements Al、Fe、K、Ti、Ba、Be、Mn、V、Ti、Ba and other stability element have a moderate to strong autocorrelation. Although the spatial correlation are influenced by random factors (e.g. cultivation fertilize transportation and other manufacture in the region) P and heavy metals Zn、Pb、Ni、Cu have a complicated spatial characteristic, but not destroyed the primitive structure. 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. Element cadmium is heavy metal but it is show the same class with Ca and Sr, may be due to industrial and agricultural, transportation and other activities effects, resulting in distribution of Cd has a larger variability and strong spatial variability in the study area, then there has no spatial autocorrelation in the sampling scale. Because of the environment change and human farming in region, element Na also has a bad spatial correlation.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 derived predominantly from terrigenous source materials, those elements affected by intensity factors of the runoff erosion; among them, heavy metals enrichment factor（Co、Cr、Cu、Ni、Pb、V、Zn etc.）and P have a significant changes after 1960 AD because of anthropogenic activities. The ordered specimen cluster analysis method was applied to study the lake environmental changes base on the enrichment factors of heavy metals and P; It was found that the environmental evolution of Ebinur Lake watershed since1875 AD can be divided into 2 different stages with 23 cm ( 1960 AD ) for the sector:Stage I 1875～1960 AD, the heavy metal enrichment factors have a low values, the contents of clay have a high values and a low waves; At this stage there had a sparse population in the watershed, environmental evolution mainly affected by regional climate changes.Stage II, 1960 AD～ Present, with the increase of population, development of economic, most of the heavy metals and P enrichment factors increased significantly and a larger fluctuations. The environmental evolu-tion was dominated by anthropogenic activities and climate change, and anthropogenic activities were grad-ually strengthened. The second assemblage included Mg and Na consisted of autogenetic evaporative minerals, with the strengthening of anthropogenic such as development of oasis agriculture, increase of irrigation water and climate change lake levels undergoing tremendous fluctuations, which influence the concentration change of Mg and Na. the third assemblage included Ca and Sr, its derived from a dissolved terrigenous bi-carbonate, and was deposited in the lake as solid carbonate.⑤ Enrichment factor and potential ecological risk assessment showed the element in topsoil had obviously influence by anthropogenic activities, especially EF value of element Cd, and has the highest value of Eri =287.6, show the extremely strong pollution. Followed by elements Ni and Cu, the Ni show the highest Eri value of 25.7. Overall, the average RI value of those eight elements in topsoil is 85.5, show a slightly potential ecological risk, and the mostly sample points of high RI value are in regionals of highway line, agricultural areas and the hometown. Although the heavy metal in sediment core show an obvious accumulation after 1960 AD, the pollution level of those heavy metal are lower than elements in topsoil. 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. |
| 中文关键词 | 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 |
| 英文关键词 | Ebinur Lake Basin Sediments Element Geochemical Environment Evolution History Potential Ecological Risk |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 自然地理学 |
| 来源机构 | 中国科学院新疆生态与地理研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/288023 |
| 推荐引用方式 GB/T 7714 | 丁之勇. 艾比湖流域沉积物元素地球化学特征及其 揭示的环境信息[D]. 中国科学院大学,2017. |
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