细菌3-羟基脂肪酸环境代用新指标的构建及其在石笋中的应用

发布时间：2018-02-24 10:23

本文关键词： 古气候石笋土壤 3-羟基脂肪酸脂肪酸单体碳同位素　出处：《中国地质大学》2016年博士论文　论文类型：学位论文

【摘要】：全球变化日益受到人们的关注,人们亟需了解地质历史时期的气候变化规律,从而预测未来气候的变化。石笋由于其产生连续、高分辨率不受干扰的记录,精确的年代学以及全球陆地广泛分布等独特的优势,已成为21世纪以来全球气候变化研究中一类重要的陆相地质载体,近年来,在国内外学者的共同努力下,石笋中越来越多的环境替代指标被挖掘用于重建古气候,包括：氧同位素,碳同位素,二元同位素,年层,微量元素,磁信息,包裹体和生物标志物等。在这些气候替代指标中,氧同位素的应用最为广泛,逐渐成为石笋分析的主流或标准方法。然而,氧同位素记录的是混合的气候信号,受到区域尺度上温度的变化,源水的同位素组成,降水以及其它复杂的因素的影响,因此对石笋氧同位素记录的解译需要考虑特定的沉积环境,并对相互作用的复杂因素进行相关解析。石笋中含有丰富的生物标志化合物,尽管其类脂物的来源相对复杂,但特定的化合物来源较为单一,尤其是来源于微生物的类脂。如3-羟基脂肪酸(3-hydroxy fatty acids,缩写为3-OH-FAs),对环境变化敏感,并能很好地保存在石笋中,具有重建古环境的巨大潜力。3-羟基脂肪酸主要来源于革兰氏阴性细菌的细胞膜磷脂脂多糖(LPS)的脂质A (Lipid A),通过酯键或酰胺键与大分子键和,因而不易降解,能够较为完好的保存在沉积物中。前人对石笋类脂提取的方法研究中,由洞穴石笋中检测出含量丰富的类脂,然而用于古气候重建的研究则非常少。因此本论文主要研究目标是,进一步优化提取方法,在最优方法下提取土壤以及洞穴沉积物中的3-羟基脂肪酸,分析其与环境因子间的相互关系,尝试建立基于3-羟基脂肪酸构建的环境替代指标,并将其应用到石笋古气候重建中。本论文的获得的主要认识如下：1.基于土壤3-羟基脂肪酸构建的温度、pH替代指标提出基于土壤3-羟基脂肪酸构建的温度和pH替代指标。对神农架不同海拔高度土壤样品中3-羟基脂肪酸与环境参数之间的关系研究发现,支链比指数(RIAN)、支链化指数(Branched Index)以及异构化比(RIN)均与土壤pH高度相关。此外,RAN15和RAN17与年均大气温度(MAAT)和年均降雨量(MAP)表现出显著的相关性。由于神农架常年处于湿润环境,MAP不可能成为微生物生态限制因素,因此推测MAAT是控制RAN15和RAN17变化的主要因素。需要注意的是,3-羟基脂肪酸的温度替代指标RAN15和RAN17是独立于pH的,因此在pH值变化较大或者可能存在多个混杂变量的环境中用于古温度重建具有很大优势。基于神农架表层土壤中3-羟基脂肪酸的pH和MAAT替代新指标对古气候和环境研究具有深远意义。通过将3-羟基脂肪酸的pH和温度替代指标与GDGT的环境替代指标相结合,可以进行多指标的陆相古温度和pH重建。此外,本论文在甘肃天池湖泊沉积物,波罗的海海洋沉积物和湖北清江和尚洞石笋中均发现了含量丰富的3-羟基脂肪酸,说明3-羟基脂肪酸分布广泛,进一步表明3-羟基脂肪酸的环境替代指标具有广泛的应用前景。在不同载体中,3-羟基脂肪酸变化的差异可能是不同的环境因子影响细菌细胞膜变化的结果。然而,本论文仅在天池湖泊沉积物中检测到偶碳数(C12,C14,C16,C18)一元不饱和3-羟基脂肪酸,说明天池湖泊沉积物中的3-羟基脂肪酸的来源较为特殊,因此针对特定的沉积环境可能需要建立新的3-羟基脂肪酸环境替代指标。2.3-羟基脂肪酸环境替代指标重建古温度和古水文本文系统地对比3-羟基脂肪酸在和尚洞洞顶上覆土壤,洞穴表层沉积物和HS4石笋中的分布特征。结果显示,洞顶土壤、洞穴表层沉积物和HS4石笋中3-羟基脂肪酸的分布相似,但石笋样品中n-C12和i-C173-羟基脂肪酸的含量较高,推断可能来源于石笋生长过程中被包裹在石笋晶格中的微生物。将基于神农架土壤建立的3-羟基脂肪酸温度指标RAN15应用到HS4石笋中,恢复长江中游地区9 ka BP以来的温度变化,其温度变化范围为17.8到20.2℃。其中早中全新世是一个相对暖的时期(8.6-5.2 ka BP),5.2 ka BP以后温度逐渐降低。RAN15重建的温度与洞穴外长期监测的18℃年均温接近。建立洞穴系统中基于3-羟基脂肪酸的水文指标,并将其应用到石笋中,重建了长江中游9 ka BP以来的水文条件变化。由于洞穴沉积物的pH变化范围很小,因此神农架土壤建立的3-羟基脂肪酸的pH指标在洞穴系统中并不适用,需要建立洞穴系统的pH公式。我们对洞顶上覆土壤和洞穴表层沉积物中的3-羟基脂肪酸分布的调查发现,i-C15和a-C15的比值(C15水文指数)与样品的pH有很好的线性相关(R2为0.65,p0.001)。根据C1s水文指数与降雨量间的半定量关系,将C15水文指数应用到石笋中,重建了过去9 kaBP以来的古水文变化。从C15水文指数反演出的古水文记录观察到两个持续较长时间的相对湿润阶段(8.1-6.0 ka BP和3.5-0 ka BP)和一个相对干旱阶段(6.0-3.5 ka BP)。同时还有几次显著的干旱事件,分别发生在8.2 ka BP,3.8 ka BP和0.5 ka BP。3.石笋中脂肪酸的单体碳同位素重建古植被信息对石笋中的脂肪酸进行单体同位素分析,并重建长江中游9 ka BP以来的植被变化。洞顶土壤、洞内表层沉积物以及HS4石笋样品中脂肪酸的分布类似。碳数分布为C12-C32,表现出明显的偶奇优势,主峰碳均为C16。石笋中低碳数脂肪酸的来源复杂,既有高等植物的贡献,也有土壤微生物以及洞穴微生物的贡献,而高碳数脂肪酸则主要来源于高等植物。C16脂肪酸的碳同位素(δ13C16 FA)变化范围为-27.5‰到-25.2‰,C18脂肪酸的碳同位素(613C18 FA)的变化范围为-27.0‰到-23.4‰。δ13C16 FAδ13C18 FA的变化趋势一致,说明两者的来源基本相同。HS4石笋中高碳数脂肪酸C22和C24的碳同位素(分别用δ13C22FA和813C24FA表示)变化范围比低碳数脂肪酸更大,δ13C22FA从-32.9‰到-25.7‰,δ13C24 FA从-33.5%o到-25.29‰。根据HS4石笋中δ13C24 FA的值以及C3和C4植物中C24脂肪酸碳同位素的平均值重建了长江中游地区9 ka BP以来的古植被变化。植被的变化特征主要分为三个阶段：第一阶段8.6-6.8 ka BP,C3植物比例逐渐增加,C4植物比例逐渐减小；第二阶段6.8-3.3 ka BP,C3植物比例逐渐减小,C4植物比例逐渐增加；第三阶段3.3-0 ka BP,C3和C4植物比例波动频繁,呈现周期性变化。长江中游地区植被的变化主要受温度控制,水文条件对植被的变化也有一定的影响。总之,本论文初步建立基于3-羟基脂肪酸的温度、pH替代指标,并在石笋中得到较好的应用,揭示长江中游地区全新世9 ka BP以来的古温度和古水文变化。此外,本论文首次对石笋中脂肪酸进行单体碳同位素分析,并重建长江中游地区9ka BP以来的古植被变化。希望通过本研究能够开辟3-羟基脂肪酸和石笋类脂单体同位素的研究新方向。
[Abstract]:Global change has been concerned, people need to understand the climate changes in the geological history, so as to predict future climate change. Because of the stalagmite to produce continuous, high-resolution undisturbed record, the precise chronology of the global land and the advantages of widely distributed and unique, has become since twenty-first Century a study of global climate change an important continental geological carrier, in recent years, with the joint efforts of the scholars at home and abroad, more and more environmental indexes in stalagmite mining was used to reconstruct the paleoclimate, including: oxygen isotope, carbon isotope, two yuan annual layer, isotope, trace elements, magnetic information, inclusions and biomarkers in these. The climatic indexes, the most widely used oxygen isotope, has gradually become the mainstream of stalagmites or standard methods. However, the oxygen isotope record is mixed climate signal, by To change the temperature on a regional scale, water isotopic composition, precipitation and other complex factors, so the translation needs to consider the specific depositional environment solution of stalagmite oxygen isotope records, and complex factors on the interaction of biomarkers related to parsing. Contains rich in stalagmite, although the source of the lipids is relatively complex, but specific compound source is relatively single, especially from microbial lipids such as 3- hydroxy fatty acids (3-hydroxy fatty acids, abbreviated as 3-OH-FAs), sensitive to the change of the environment, and can be well preserved in the stalagmite, with great potential of.3- hydroxy fatty acid the main source of paleoenvironment reconstruction in gram negative bacterial cell membrane phospholipid lipopolysaccharide (LPS) lipid A (Lipid, A) by ester or amide bonds with large molecular bonds and, therefore not easy to degrade, can be preserved in the sink Deposit. Previous research methods for the extraction of lipids from Stalagmite in the stalagmite was detected in the rich content of lipids, but for the study of paleoclimate reconstruction is very small. So the main goal of this thesis is to further optimize the extraction method, extraction method, the optimal 3- hydroxy fatty soil and cave sediments acid, analysis of its relationship with the environmental factors, try to establish 3- hydroxy fatty acid construction environment substitute index based, and its application to the stalagmite paleoclimate reconstruction obtained. The main conclusions of this paper are as follows: 1. based on soil 3- hydroxy fatty acid construction temperature, pH index of soil 3- hydroxy fatty replacement the acid temperature and pH index. Based on the study of alternative relationship between different altitudes in Shennongjia soil samples 3- hydroxy fatty acids and environmental parameters, branch ratio index (RIAN), branched Index (Branched Index) and the ratio of isomerization (RIN) were highly correlated with soil pH. In addition, RAN15 and RAN17 (MAAT) and the average air temperature and annual precipitation (MAP) showed a significant correlation. Because Shennongjia is in the moist environment can not become a perennial, MAP micro biological and ecological factors, suggesting that MAAT is the main factors that control the RAN15 and RAN17 changes. Note that the temperature of 3- hydroxy fatty acid substitution indexes of RAN15 and RAN17 are independent of pH, so the pH value changes greatly or there may be a number of confounding variables in the environment of palaeoreconstructions has great advantages. 3- hydroxy fatty acids in the surface soil of Shennongjia pH and MAAT instead of the new index is of far-reaching significance for the study of paleoclimate and environment. Based on the environmental indexes of 3- hydroxy fatty acid pH and temperature alternative indicators combined with GDGT, can be a The Lu Xianggu temperature and pH reconstruction. In addition, the sediments of Gansu Tianchi Lake, the Baltic Sea sediment and Hubei Qingjiang monk Cave Stalagmite was found in 3- hydroxy fatty acid, 3- hydroxy fatty acids are widely distributed, further showed that 3- hydroxy fatty acid environment substitute index has a wide application prospect. In different carriers, different changes of 3- hydroxy fatty acids may be the bacterial cell membrane environment factors affecting the change of different results. However, this thesis only in the Tianchi lake sediments detected even carbon number (C12, C14, C16, C18) 3- hydroxy mono unsaturated fatty acids, explain the sources of 3- hydroxy fatty acids in the sediments of Tianchi Lake is very special, so the specific depositional environment may need to establish a new environment 3- hydroxy fatty acid substitution index.2.3- hydroxy fatty acid environment substitute index paleotemperature reconstruction And the ancient water text paper comparing 3- hydroxy fatty acids in the monk hole top cover soil, the distribution characteristics of cave sediments and HS4 in stalagmite. The results showed that the soil, similar to the distribution of 3- hydroxy fatty acid and HS4 in surface sediments of cave stalagmites, but n-C12 and i-C173- hydroxy fatty acids in stalagmite samples higher content of inference may be derived from the stalagmite growth process is wrapped in Stalagmite in the lattice will be based on Shennongjia soil microorganisms. The establishment of the 3- hydroxy fatty acid temperature index RAN15 to HS4 in the stalagmite, restoration of the middle reaches of the Yangtze River 9 Ka BP since the temperature changes, the temperature changes in the range of 17.8 to 20.2 degrees. The early in the the Holocene is a relatively warm period (8.6-5.2 Ka BP), 5.2 Ka BP after the temperature is gradually reduced temperature and cave.RAN15 reconstruction outside the long-term monitoring of the annual temperature close to 18 degrees. The establishment of the cave system in the base In the 3- hydrological index hydroxy fatty acid, and its application to the reconstruction of the Stalagmite in the middle reaches of the Yangtze River hydrological conditions. Since 9 Ka BP due to pH changes in the scope of the cave sediments is very small, so the pH index of 3- hydroxy fatty acid soil of Shennongjia established does not apply in the cave system, the pH formula to establish the cave system. We found that the investigation of roof overlying soil and cave in the surface sediments of 3- hydroxy fatty acid distribution, the ratio of i-C15 and a-C15 (C15 hydrology index) have good linear correlation with the sample of pH (R2 = 0.65, p0.001). According to the semi quantitative relationship between C1s hydrology index and rainfall. The C15 index is applied to the hydrology in the stalagmite, the reconstruction of the ancient hydrological changes over the past 9 kaBP. Since the ancient hydrological records from C15 hydrology index inversion observed relatively humid stage two of longer duration (8.1-6.0 Ka BP and 3.5-0 Ka BP) And a relatively arid stage (6.0-3.5 Ka BP). At the same time, there are several significant drought events occurred in 8.2, Ka BP respectively, 3.8 Ka BP and 0.5 Ka BP.3. in stalagmite monomer carbon isotope fatty acid reconstruction of paleovegetation information on fatty acid analysis of the monomer in the stalagmite isotope, and vegetation reconstruction changes in the middle reaches of the Yangtze River since 9 Ka BP. The soil, the surface sediments and the distribution of the fatty acids in the sample. HS4 from similar carbon number distribution of C12-C32, showed the even odd predominance, the peak carbon was C16. from low carbon number fatty acid complex sources, both higher plants have contribution. Soil microbe and microbial cave contribution and high carbon number fatty acids were mainly originated from the carbon isotope of higher plant.C16 fatty acids (delta 13C16 FA) ranged from -27.5% to -25.2%, the carbon isotope of fatty acid C18 (613C18 FA) in the range -27.0% to -23.4% in the same trend. 8 13C16 FA Delta 13C18 FA, shows that the carbon isotope of high carbon number fatty acids C22 and C24 both sources are basically the same.HS4 in stalagmite (represented as delta 13C22FA and 813C24FA) range greater than low carbon number fatty acids, Delta 13C22FA from -32.9 1000 -25.7 13C24 FA 8%, from -33.5%o to -25.29 per thousand. According to HS4 in stalagmite Delta 13C24 values of FA and C3 and C4 C24 in plant fatty acid carbon isotope average value of the reconstruction of the middle reaches of the Yangtze River 9 Ka BP since the paleovegetation changes. The variation of vegetation is mainly divided into three stages: the first stage 8.6-6.8 Ka BP, C3 plant proportion gradually increased, the proportion of C4 plants decreased gradually; the second stage of 6.8-3.3 Ka BP, C3 plant ratio decreased, the proportion of C4 plants increased gradually; the third stage 3.3-0 Ka BP C3, and the proportion of C4 plants fluctuated frequently presents periodic variation in the Yangtze river. Change of tourism in the area of vegetation is mainly controlled by temperature, changes in hydrological conditions of vegetation have a certain effect. In short, this paper established 3- hydroxy fatty acid based on the temperature of pH alternative indicators, and get better application in stalagmite, paleo temperature and paleo hydrologic changes since Holocene in the middle reaches of the Yangtze River region revealed 9 Ka BP. In addition, this is the first time that specific carbon isotope analysis of fatty acid in the stalagmite, and reconstruction of the middle reaches of the Yangtze River 9ka BP since the paleovegetational changes. Hope that through this study can open up the lipid hydroxy fatty acid monomer and stalagmite 3- isotopes of the new research direction.

【学位授予单位】：中国地质大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P532;P593

【参考文献】