EGI OpenIR
巴尔喀什湖沉积物元素地球化学特征与沉积环境演变
Alternative TitleGeochemical Characteristics of Elements and its Responses to Sedimentary Environmental Change Recorded in Lacustrine Sediments from Balkhash Lake, Central Asia
黄坤
Subtype硕士
Thesis Advisor吉力力·阿不都外力 ; 马
2020-06-30
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline理学硕士
Keyword巴尔喀什湖流域 沉积物 元素地球化学 环境变化 中亚湖泊 Lake Balkhash Sediment Element geochemistry Environmental evolution Lakes in Central Asia
Abstract湖泊沉积物汇集了流域内物质, 是区域环境变化的优良档案,具有连续性,分辨率高和信息丰富的特征, 广泛应用于环境变化和人类活动重建的研究中。 湖泊沉积物中的元素一般来源于湖泊流域的集水区,自然条件下主要与流域母岩性质、 风化条件以及元素地球化学过程等有关, 而随着工业革命以来现代化进程的推进, 沉积物中元素受到人类活动的影响持续增强。 不同深度的沉积物保存了与其相对应年代的环境信息, 湖泊沉积物元素地球化学的垂向特征有助于认识流域自然环境的演化以及人类活动对重金属污染的历史。本文选取位处亚洲中部干旱区的大型内陆湖泊巴尔喀什湖为研究对象, 在湖区西部采集了一根长 74 cm 的岩芯沉积物, 利用流域气候、水文以及湖泊沉积物元素地球化学指标等数据,根据滑动平均法、 小波分析法分析了流域现代时期的气候因子变化特征以及湖水位的影响因素,通过统计分析、有序聚类分析、潜在生态风险评价研究了巴尔喀什湖湖泊沉积物的元素地球化学特征和来源, 并重建近 200 年来自然过程和人类活动影响下的湖泊环境变化, 为巴尔喀什湖的环境保护和管理实践提供支持。 主要结论如下:(1) 通过对巴尔喀什湖流域气象水文资料分析, 研究了器测时期以来流域环境变化,结果表明流域气温降水总体呈升高趋势,湖水位波动频繁。 小波分析结果表明湖水位存在以 83a 和 47a 为中心尺度的周期,其中 83a 周期对小波方差贡献最大为主周期,在该尺度下目前湖水位正处于相对较高的时期,此后将逐步进入枯水期。(2)利用交叉小波分析了湖水位变化的影响因素,表明气温与径流在 20 世纪 80 年代的显著共振周期相位由负转正,指示增温加快导致冰雪融水补给的增加超过蒸发引起的损耗,加之同时期降水量的增加使湖水位的迅速回升。降水是自然状态下影响径流和湖水位变化的主要原因, 大气环流因子通过控制降水从而影响研究区内入湖径流和湖水位变化。其中, NAO 对湖水位变化起主导作用,并存在 2~4a 的滞后,而 SOI 反映的厄尔尼诺事件则与 1987 年后湖水位回升联系密切。(3) 综合多元统计分析,巴尔喀什湖岩芯沉积物中元素主要可分为三个组分,第一组为 Al、 Fe、 K、 Mg、 Mn、 P、 Sr、 Ti、 V、 Cr、 Co、 Ni、 Cu、 Zn、 Cd以 Pb 等元素, 主要反映了陆源碎屑矿物输入,其中 Cu、 Cd、 Pb 等重金属元素在沉积物上部呈增加趋势,可能与近几十年来流域的人为输入有关。第二组为 Sr与 Na 元素,反映了流域的化学风化作用。 第三组为 Ca 和 Ba 元素, 主要来源于湖泊水体中的自生碳酸盐沉淀。(4) 根据元素影响因素分析结果, 第一组中的 Al 和 K 等主量元素在 1860和 1920 年左右分别经历了两次快速增加,其内在机制不同。第一次快速增加事件是由于盆地内气候迅速向湿润过渡, 入湖径流携带的元素含量增加, 而第二次快速增加事件与伊犁三角洲的发育密切相关。 20 世纪 60 年代以后大量的自生碳酸盐沉淀则反映了区域温度的升高以及农业灌溉回水进入湖泊。(5)利用样品有序聚类将巴尔喀什湖岩芯沉积物重金属污染的演化分为两个阶段。 在阶段Ⅰ (1797-1930AD), 重金属元素含量变化与区域地质背景和自然气候变化有关。 在阶段Ⅱ(1930-2017AD),自 20 世纪 30 年代起巴尔喀什湖北岸的采矿和冶金等工业生产排污导致重金属 Cu、 Cd、 Pb 的不断富集, 特别是 Cd根据潜在风险评价已对当地生态系统构成中度风险。 而同为中亚干旱区湖泊的博斯腾湖、艾比湖和柴窝堡湖的沉积物重金属的污染从 20 世纪 50-60 年代开始,受到农业灌溉回水以及流域内生活和工业生产排污影响, 受人类活动影响的重金属以 Pb、 Cd、 Ni 为主,总体上污染程度相对较轻。
Other AbstractLake sediments are excellent archives of regional environment changes, withcharacteristics of continuity, high resolution and abundant information. Elements inlake sediments generally originated from weathered mother rock, soil erosion, andanthropogenic input, therefore, have been widely used in the research on environmentchange and human impacts reconstruction. With the promotion of modernization drivesince industrial revolution, the profile of elements has been affected by human activities,not only natural process Sediments of different depths preserve environmentalinformation of corresponding ages. The vertical characteristics of element geochemistryof lake sediments are helpful for understanding the evolution of the natural environmentof the basin and the history of heavy metal pollution by human activities.This study takes the Lake Balkhash as the research object, which is a huge inlandlake in arid regions of Central Asia. A 74 cm long core sediment was collected in thewest of the lake district. Based on the meteorological and hydrological data of the basinand multi-proxy analysis of a sediment core from Lake Balkhash, the moving averagemethod, wavelet analysis, statistical analysis, ordered cluster analysis and potentialecological risk assessment are used in this study, which aims to Analysis of identify thesource of the elements, and to reconstruct environmental evolution of the lake underthe interaction of human activities and natural process. This study will provide supportfor the environmental protection and better management practices in Lake Balkhash.The main conclusions are summarized as follows:(1) Based on the analysis of meteorological and hydrological data in the LakeBalkhash Basin, the environmental changes of the basin in observation period arestudied. The annual temperature and precipitation in the basin have generally increased.The results of continuous wavelet analysis suggest that a main cycle for 83a is thecentral scale, with an average period of lake level change for 54a. The lake level hasexperienced three transition of abundance and dryness since 1880, and it will graduallyenter next dry season in the future.(2) The cross-wavelet analysis reveals that the precipitation is the main reason forlake level change under natural conditions. What’s more, the transition of resonancecycle phase between temperature and runoff in the late 1980s indicates that theincreasing melt water supply due to rising temperature results the recovery of lake level,instead of a negative effect of evaporation loss. The variation of runoff and lake levelcan be influenced by atmospheric circulation in the region through controllingprecipitation. The relationship of cross-wavelet analysis between NAO and runoff ismore closely compared to SO, that play a more important role to lake level changes.(3) Comprehensive statistical analysis results show that the elements in the coresediments of Lake Balkhash can be divided into three groups. The first group includesAl, Fe, K, Mg, Mn, P, Sr, Ti, V, Cr, Co, Ni, Cu, Zn, Cd and Pb, with high correlationcoefficients. These elements mainly reflect the input of terrigenous clastic minerals.Among them, heavy metals for Cu, Cd and Pb are increasing in the above of the core,which may be related to anthropogenic input in the basin in recent decades. The secondgroup is Sr and Na, which reflects the chemical weathering of the basin. The third groupincludes Ca and Ba They are mainly come from authigenic carbonate precipitation inthe lake water.(4) The major elements including Al and K in the first group have experienced twoperiods of enrichment in 1860s and 1920s respectively, with different underlyingmechanisms. The first enrichment event was caused by a quick transition of the climateto wet in the basin, whereas a dramatically increasing concentration of elements duringsecond period of enrichment for conservative elements was closely related to thedevelopment of Ili delta. The intensive autochthonous calcite precipitation after 1960sreflected the rising regional temperature, as well as massive wastewater from irrigationentering the lake.(5) The evolution of heavy metal contamination in the core could be divided intotwo stages. In the Stage Ⅰ (1797-1930 AD), concentrations of heavy metals wascontrolled by regional climate and geological background. Since the Balkhash Miningand Metallurgical Combine was established in 1930s (the Stage Ⅱ ), discharge ofindustrial untreated wastewater resulted the accumulation of heavy metal Cu, Cd andPb, in particular, Cd posed a potentially moderate risk to the local ecosystem accordingto the classification. It exhibits spatial difference with Bosten Lake, Ebinur Lake andChaiwopu Lake, all in arid central Asia, which began to be disturbed by humanactivities from the 1960s.
Subject Area自然地理学
Language中文
Document Type学位论文
Identifierhttp://ir.xjlas.org/handle/365004/15444
Collection中国科学院新疆生态与地理研究所
研究系统
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
黄坤. 巴尔喀什湖沉积物元素地球化学特征与沉积环境演变[D]. 北京. 中国科学院大学,2020.
Files in This Item:
There are no files associated with this item.
Related Services
Recommend this item
Bookmark
Usage statistics
Export to Endnote
Google Scholar
Similar articles in Google Scholar
[黄坤]'s Articles
Baidu academic
Similar articles in Baidu academic
[黄坤]'s Articles
Bing Scholar
Similar articles in Bing Scholar
[黄坤]'s Articles
Terms of Use
No data!
Social Bookmark/Share
All comments (0)
No comment.
 

Items in the repository are protected by copyright, with all rights reserved, unless otherwise indicated.