东北泥炭记录的全新世气候环境变化与大气汞沉降研究

发布时间：2018-06-07 12:00

  本文选题：全新世 + 泥炭　； 参考：《中国地质大学》2017年博士论文

【摘要】：人类生存于地球系统之中,地球环境的变化与人类社会的发展息息相关。为了获得更好的生存和发展条件,人们迫切希望了解和掌握全球环境、气候的变化规律,期望预知未来气候与环境变化的趋势、幅度和影响,并尝试利用人类的智慧和技术手段来解决这些问题。为此,全球变化研究成为了当下急需探索的重要课题。过去全球变化研究(Past Global Changes,PAGES)是全球变化研究计划中重要分支,旨在通过研究地球过去气候和环境变化来预测和获取未来全球环境变化的信息,为人类可持续发展提供战略性支持。通过各种沉积材料和信息载体进行过去气候和环境的恢复与重建是了解和探索全球环境系统变化规律和机制的重要手段,也是全球变化课题的重要研究方向。在过去历史发展进程中,从11.5ka开始延续至今的全新世(Holocene)是最年轻的地质时代,也是与人类文明发展和繁荣密切相关的一个重要时期。在此期间,全球气候环境发生了非常频繁的、迅速的变化,对人类的生存环境带来了极大的改变。在过去气候环境变化过程中,近几千年来的气候与未来的气候变化最为接近;而近万年的气候变化则反映了自然背景下叠加的人类活动干扰,不仅记录了气候变化的自然规律,同时记录了人类活动的影响,这对预测未来的气候变化是必需的。因此,对全新世气候与环境变化的研究既是人类可持续发展的需要,也是我们通过了解过去地球环境演变来预测未来全球变化的重要手段,对于人类具有十分重要的意义。那么,获取能够完整记录全新世气候环境变化的信息的连续沉积档案材料是相当关键的。泥炭是第四纪,特别是全新世以来产生的不同分解程度的松软有机沉积物,其形成过程受到不同气候、水文等条件的影响。作为环境演变的信息载体,泥炭与冰芯、黄土、湖泊沉积物一样,已被证明是气候变化的重要储存库和档案馆。与其他陆地沉积物相比,泥炭具有经济易得、沉积速率较快且沉积连续、沉积环境与过程稳定、时间尺度长和其适合的代用指标广泛等优势,因此它是研究过去气候环境变化的理想档案材料,在缺乏历史记载、冰芯、树轮和珊瑚礁等记录体的区域更体现出其特有的价值。本文以富含古气候环境变化信息的中国东北地区哈尼泥炭沉积物为研究对象,通过提取泥炭中古气候环境代用指标进行对比分析,讨论了各气候环境代用指标的古气候意义,恢复了区域全新世以来的古气候环境变化过程。同时,对泥炭记录的大气汞含量和汞沉降通量进行了测定,恢复了东北地区全新世以来的大气汞沉降历史,并研究了东北地区大气汞沉降与全新世气候变化和火山喷发事件的响应,初步探讨了其可能存在的内在机制,为泥炭地质档案的全球变化研究提供新的思路。论文的主要内容和研究成果如下:1、本文首先从泥炭年代学、泥炭气候环境代用指标、泥炭记录的大气汞沉降历史、泥炭记录的火山喷发事件等研究方向介绍了泥炭古气候与环境的国内外研究进展。同时,对泥炭的形成分布、泥炭古气候环境研究方法和优势以及汞的基本理化性质、迁移转化、分布来源进行了讨论和阐述。2、选择中国东北地区哈尼泥炭地作为研究区域,对研究区内地质地貌、气候水文、植被土壤等自然背景进行了介绍。以哈尼泥炭沉积物为研究对象,详细叙述了泥炭样品采集和前处理过程,同时总结和讨论了各环境代用指标的研究方法及实验过程。3、根据在东北哈尼泥炭地野外采样现场对泥炭样品的颜色和岩性的详细记录设置泥炭层位控制点,采用AMS14C测年技术对控制点泥炭样品进行测定,共获取12个泥炭植物纤维素14C年龄,并使用CALIB4.3软件对泥炭14C年龄进行校正。结合泥炭剖面深度和年代数据,采用分段式线性内插方法来建立东北哈尼泥炭剖面年代学框架,结果显示:哈尼泥炭剖面最大深度为9米,泥炭沉积年代下限校正年龄为13937a BP(对应14C年龄为11930±172a BP),泥炭沉积速率范围为0.018cm/yr~0.311cm/yr。4、采用碱提取溶液吸光度法对哈尼泥炭腐殖化度进行测试,以540nm波长下吸光度值来表征腐殖化度大小。同时,采用Kappbridge MFK1-FA磁化率仪分别在低频磁化率F1(976HZ)和高频率磁化率F3(1561HZ)条件下对哈尼泥炭样品进行磁化率的测定。通过与哈尼泥炭纤维素δ13C和δ18O气候代用指标对比,确立了哈尼泥炭腐殖化度和泥炭磁化率指标的古气候意义:哈尼泥炭腐殖化度和泥炭磁化率记录了环境温度和湿度变化信息,较高的泥炭腐殖化度和泥炭磁化率指示气候温暖湿润,较低的泥炭腐殖化度和泥炭磁化率指示气候干燥寒冷。5、东北哈尼泥炭纤维素δ13C、δ18O气候代用指标以及泥炭腐殖化度和泥炭磁化率指标对新仙女木事件、8.2ka BP事件、4.2ka BP事件等多次气候突变事件存在显著的响应,表现在气温迅速下降气候变干冷,这表明东北哈尼地区在全新世期间的气候变化与全球变化保持相对一致。同时,通过多环境代用指标体系对东北哈尼地区14.0ka BP的气候环境演化过程进行了探讨,可以划分为以下六个阶段:14.0~11.5ka BP末次冰消期气候寒冷阶段;11.5~9.8ka BP全新世早期气候温暖湿润阶段;9.8~8.0ka BP气候快速变化干燥寒冷阶段;8.0~4.8ka BP全新世中期气候适宜温暖湿润阶段;4.8~1.8ka BP气候冷暖干湿交替阶段;1.8~0ka BP全新世晚期气候干燥寒冷阶段。6、采用王水水浴法对泥炭样品进行消解,并使用AFS-8230双道原子荧光光谱仪消解后样品中汞含量进行了测试。通过对东北哈尼泥炭汞含量和大气汞沉降通量的研究表明,泥炭中汞含量波动范围为1.6~508.8ng/g,平均值为45.133ng/g;大气汞沉降通量波动范围为0.12~102.63μg.m-2.yr-1,平均值为8.14μg.m-2.yr-1。哈尼泥炭较为完整地记录了东北地区全新世以来的大气汞沉降历史,可以划分为以下五个阶段:11.5~10.2ka BP大气汞沉降快速波动上升阶段;10.2~9.0ka BP大气汞沉降快速下降阶段;9.0~8.0ka BP大气汞沉降剧烈波动异常阶段;8.0~2.0ka BP大气汞沉降稳定交替波动减弱阶段;2.0~0ka BP大气汞沉降波动快速上升阶段。7、哈尼泥炭记录的东北地区大气汞沉降对包括YD事件、11.1ka BP事件、10.3ka BP事件、8.2ka BP事件、4.2ka BP事件以及小冰期等气候突变寒冷事件有着良好响应,大气汞沉降含量和沉降通量在这些气候突变寒冷事件发生期间同时达到极高峰值。将东北地区全新世气候变化与大气汞沉降历史对比研究发现:当东北地区气候经历干燥寒冷阶段时,大气汞沉降得到显著增强;当气候经历温暖湿润阶段时,大气汞沉降相应减弱。因此推断,气候干燥寒冷有利于促进东北地区大气汞沉降,反之亦然。8、采用酸化法对哈尼泥炭中火山灰层进行了提取,使用偏光显微镜、环境扫描电镜、电子探针测试等技术手段对火山灰的形态和化学成分进行了研究。结合火山灰层年代,推断其来自于长白山天池火山在全新世冰场期的爆发,火山喷发物年代为8352±76a BP~9604±80a BP(AMS14C年龄),校正年龄为9337~10745a BP。同时,将东北地区大气汞沉降历史与全新世期间东北地区和东亚地区火山喷发事件对比研究发现:东北地区大气汞沉降对上全新世东北地区和东亚地区较强规模火山喷发事件存在显著的响应,在强火山喷发期间哈尼泥炭记录的东北地区大气汞含量和沉降通量总是保持较高水平或者出现极高峰值。因此推断,较大规模的火山喷发事件可以造成区域或全球大气汞在短时间内急剧升高,并造成局部或大范围大气汞沉降迅速增强。9、东北地区大气汞沉降对全新世气候变化响应的内在机制可能为:从百年或千年尺度来看,干燥寒冷的气候可以造成大气中气态单质汞活性降低,在冷凝作用下沉降速度加快,泥炭地中植物可以接受全球范围内气态单质汞补给,泥炭记录的大气汞含量和大气汞沉降通量增强;温暖湿润的气候可以使大气汞中气态单质汞活性增强,使得气态单质汞下降速度减慢,泥炭地主要接受颗粒汞、氯化汞以及少量气态单质汞,大气汞沉降总量相对较少。东北地区大气汞沉降对火山喷发事件响应的内在机制可能为:全新世期间东北地区和东亚地区发生了多期次强烈的火山喷发事件,在火山喷发期间大气汞含量急剧上升,促使大气汞沉降增强;同时火山喷发产生的酸性气体如HCl、H2S等可以使大气汞水滴的pH下降,造成大气汞的酸沉降加强。另一方面,大规模的火山喷发事件造成了迅速降温,形成较为干燥寒冷的气候,促使东北地区大气汞沉降加强。火山喷发活动对大气汞的总量和沉降速度都有较好的促进作用,因此在东北地区和东亚地区较强火山喷发期间能在哈尼泥炭中找到大气汞沉降显著增强的强烈响应。
[Abstract]:Human beings live in the earth system, the change of the earth's environment is closely related to the development of human society. In order to obtain better conditions for survival and development, people are eager to understand and master the global environment, the law of climate change, anticipate the trend, amplitude and influence of the future climate and environment changes, and try to use the wisdom of human beings. The global change research (Past Global Changes, PAGES) is an important branch of the global change research program, which aims to predict and acquire future global environmental changes by studying the climate and environmental changes of the earth. It provides strategic support for the sustainable development of human beings. The restoration and reconstruction of the past climate and environment through various sedimentary materials and information carriers is an important means to understand and explore the laws and mechanisms of the changes in the global environmental system. It is also an important research direction of the global change subject. In the course of past historical development, it started from 11.5ka. The Holocene (Holocene), which continues to date, is the youngest geological age, and is also an important period closely related to the development and prosperity of human civilization. During this period, the global climate and environment have undergone very frequent and rapid changes, which have brought great changes to the living environment of human beings. In the past, nearly a few thousand of the climate and environment changed. Climate change in the past year is the closest to the future climate change, and the climate change of nearly ten thousand years reflects the superimposed human activity interference under the natural background, which not only records the natural laws of climate change, but also records the influence of human activity, which is necessary for predicting future climate change. Therefore, the climate and environment change to the Holocene. The research is not only the need of human sustainable development, but also an important means for us to predict the future global change by understanding the evolution of the earth's environment in the past. It is very important for mankind. As an information carrier for environmental evolution, peat, like ice core, loess and lake sediments, has been proved to be an important repository and archives of climate change. Compared to the ground sediments, peat has the advantages of easy economic availability, faster deposition rate and continuous deposition, stable depositional environment and process, long time scale and a wide range of suitable proxy indicators. Therefore, it is an ideal archival material for the study of changes in the climate and environment in the past, and in the absence of historical records, ice cores, tree rings, and coral reefs. In this paper, the Hun peat deposits in Northeast China, which are rich in the information of paleoclimate and environmental changes, are studied in this paper. By comparing and analyzing the paleoclimatic environment of peat, the paleoclimate significance of various climatic and environmental indicators is discussed, and the paleoclimate environment since the regional Holocene has been restored. At the same time, the atmospheric mercury content and the mercury deposition flux recorded in the peat are measured, the history of atmospheric mercury deposition in the northeastern region since the Holocene has been restored, and the atmospheric mercury deposition in the northeast region and the Holocene climate change and the response of the volcanic eruption events are studied, and the possible inherent mechanism of the mercury deposition in the northeastern region is discussed. The study of global change of geological archives provides new ideas. The main contents and research results of this paper are as follows: 1, this paper first introduces the research direction of peat's paleoclimate and environment at home and abroad from peat chronology, peat climate and environment substitute index, peat's atmospheric mercury deposition history, and peat volcanic eruption events. At the same time, the formation and distribution of peat, research methods and advantages of peat paleoclimate and environment, basic physical and chemical properties of mercury, migration and transformation, and distribution sources were discussed and expounded,.2 was selected as the study area of Hani peat land in Northeast China, and the natural background of texture, climate hydrology and vegetation soil in the study area was introduced. Taking Hani peat sediments as the research object, the sampling and pretreatment process of peat samples were described in detail. At the same time, the research methods and experimental process.3 were summarized and discussed. According to the detailed records of the color and lithology of peat samples in the field sampling site in Hani peat land in Northeast China, the control points of peat layer were set up. The AMS14C dating technique was used to measure the peat samples of control points. A total of 12 peat plant cellulose 14C ages were obtained, and CALIB4.3 software was used to correct the peat 14C age. Combined with the peat profile depth and date data, a sectional linear interpolation method was used to establish the northeastern Hani peat profile chronological framework. The maximum depth of the peat section is 9 m, and the correction age of the peat deposition time limit is 13937a BP (corresponding 14C age is 11930 + 172a BP), and the Peat Deposition rate is 0.018cm/yr~0.311cm/yr.4. The humic degree of Hani peat is tested by the alkali extraction solution absorbency method, and the humus degree is characterized by the absorbance value of the 540nm wavelength. At the same time, the magnetic susceptibility of Hani peat samples was measured under the low frequency susceptibility F1 (976HZ) and high frequency susceptibility F3 (1561HZ) with the Kappbridge MFK1-FA susceptibility tester. The paleoclimate of the humic and peat susceptibility indices of Hari peat was established by comparing with the Hani peat cellulose Delta 13C and the Delta 18O climate substitute index. Significance: Hani peat humus degree and peat susceptibility record the environmental temperature and humidity change information, high peat humification degree and peat susceptibility indicating warm and humid climate, low peat humification degree and peat susceptibility indicating climate dry and cold.5, northeast Hani peat cellulose Delta 13C, Delta 18O climate substitution index and mud The carbon humification degree and the peat susceptibility index have a significant response to the events of new immortality, 8.2ka BP event, 4.2ka BP event and so on. It shows that the climate changes dry and cold rapidly, which indicates that the climate change in the northeastern Hani region is consistent with the global change during the Holocene. The evolution process of the climate and environment of 14.0ka BP in northeastern Hani region is discussed by proxy system, which can be divided into six stages: the cold stage of 14.0~11.5ka BP at the last deglacial period, the warm and humid stage of the early climate of 11.5~9.8ka BP in the Holocene, the fast change of the dry and cold stage of the 9.8~8.0ka BP, and the 8.0~4.8ka BP in Holocene The climate is suitable for the warm and humid stage; the 4.8~1.8ka BP climate cold and warm dry and wet alternate stage; the 1.8~0ka BP in the late Holocene climate dry and cold stage.6, using the water bath method to eliminate the peat samples, and using the AFS-8230 double channel atomic fluorescence spectrometer to test the mercury content in the samples after the digestion of the two channel atomic fluorescence spectrometer. Through the Hani peat mercury in Northeast China, the mercury content is tested. The quantitative and atmospheric mercury deposition flux shows that the fluctuation range of mercury content in peat is 1.6~508.8ng/g, the average value is 45.133ng/g, the fluctuation range of atmospheric mercury deposition flux is 0.12~102.63 mu g.m-2.yr-1, and the average value of 8.14 mu g.m-2.yr-1. Hun peat is a complete record of the history of atmospheric mercury deposition in the northeastern region since Holocene. It is divided into the following five stages: 11.5~10.2ka BP atmospheric mercury deposition rapid fluctuation stage; 10.2~9.0ka BP atmospheric mercury deposition rapid decline stage; 9.0~8.0ka BP atmospheric mercury precipitation intense fluctuation phase; 8.0~2.0ka BP atmospheric mercury sedimentation stability alternating wave weakening stage; 2.0~0ka BP atmospheric mercury sedimentation fluctuation stage.7, Hani mud Atmospheric mercury deposition in carbon recorded in Northeast China has a good response to climate catastrophic cold events including YD events, 11.1ka BP events, 10.3ka BP events, 8.2ka BP events, 4.2ka BP events and small ice periods. The atmospheric mercury deposition and sedimentation flux reached a very high peak during these climate catastrophes and cold events. Compared with the historical climate change of the Holocene and the atmospheric mercury deposition, it was found that the atmospheric mercury deposition was significantly enhanced when the climate experienced a dry and cold stage in the northeast, and the atmospheric mercury deposition was weakened when the climate experienced a warm and moist stage. Therefore, it was concluded that dry cold and cold climate would promote atmospheric mercury deposition in the northeast, and vice versa. .8, the volcanic ash layer in Hani peat was extracted by acidification. The morphology and chemical composition of the volcanic ash were studied by polarizing microscope, environmental scanning electron microscope and electron probe test. The eruption of Changbai Mountain Tianchi volcano in the Holocene ice field and the eruption of volcanic eruption were deduced. The origin age is 8352 + 76a BP~9604 + 80A BP (AMS14C age), and the correction age is 9337~10745a BP.. The comparison of the history of atmospheric mercury deposition in Northeast China and the volcanic eruption events in the northeast and East Asia during the Holocene epoch found that the atmospheric mercury deposition in the northeast region has a strong scale volcano in the northeastern and East Asian regions of the upper Holocene There is a significant response to the eruption events. The atmospheric mercury content and sedimentation flux in the northeastern region of the northeastern region of the high volcano eruption always maintain a high level or high peak value. Therefore, it is inferred that large scale volcanic eruptions can cause a sharp rise in regional or global atmospheric mercury in a short time, and cause local or partial volcanic eruptions. The atmospheric mercury deposition in the large area is rapidly enhanced by.9. The internal mechanism of the response of atmospheric mercury deposition to the Holocene climate change in Northeast China may be as follows: from a hundred year or a thousand year scale, the dry and cold climate can reduce the activity of gaseous single mercury in the atmosphere, speed up the sedimentation rate under the condensation, and the plants in the peat land can accept the global model. The atmospheric mercury content and atmospheric mercury deposition flux in the atmosphere can be enhanced by the recharge of peri gaseous mercury, and the warm and humid climate can increase the activity of gaseous mercury in atmospheric mercury, slow down the decreasing velocity of gaseous mercury, and mainly accept granular mercury, mercuric chloride and a small amount of gaseous single mercury, and the total amount of mercury deposition in the atmosphere is relatively higher. The internal mechanism of the response of atmospheric mercury deposition to volcanic eruption events in Northeast China may be as follows: during the Holocene, many intense volcanic eruptions occurred in the northeast and East Asia, and the atmospheric mercury content increased sharply during the eruption of the volcano, and the atmospheric mercury deposition was enhanced, and the acid gas produced by the eruption, such as HCl, H2S On the other hand, the large-scale volcanic eruption caused the rapid cooling and the formation of a more dry and cold climate, which promoted the atmospheric mercury deposition in the northeast region. The volcanic eruption activities have a good effect on the total amount of mercury and the sedimentation rate of atmospheric mercury, because the volcanic eruption activity has a good effect on the total amount of mercury and the sedimentation rate in the atmosphere. During the strong volcanic eruption in Northeast China and East Asia, we can find strong response of atmospheric mercury deposition in Hani peat.
【学位授予单位】：中国地质大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：P532;X51
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本文编号：1991098