南海不同水深沉积物的微生物脂类分布特征及其对古环境重建的启示

发布时间：2018-03-27 13:17

本文选题：南海　切入点：GDGTs萃取方法　出处：《中国地质大学》2017年硕士论文

【摘要】：本文以中国南海表层沉积物为研究对象,对源于海洋藻类的长链二醇以及主要源于海洋古菌的标志化合物甘油二烷基甘油四醚(glycerol dialkyl glycerol tetrethers,GDGTs)进行研究,重点探讨相应化合物构建的古温度指标在南海地区的适用性。其中源于长链二醇的LDI指标在全球范围内能很好的反映温度的变化,但是在南海地区的研究尚未开展;源于古菌的TEX86温度指标在南海地区的使用情况存在指示不明确的问题,对其反映次表层温度还是季节性温度的问题尚未得到很好地解决;此外对于近几年新发现的OH-GDGTs化合物的RIOH和OH-2/OHs指标在中低纬度海洋中同样能很好的指示温度的变化,但是由于南海地区的特殊性,有值得进一步研究的必要。因此本文综合研究上述三类生物标志化合物在南海地区的分布特征以及其对于温度的响应关系,试图解析各种生物标志化合物在南海地区的使用条件和相关影响因素。前人研究表明古菌iGDGTs的分布受到水深的影响,那么海洋中深水碳酸盐补偿深度是否也会对于古菌GDGTs的分布存在影响,我们对此进行了深入的研究。结果表明GDGTs分布随着水深的变化可以分为三个不同的区间0-200m,1000-3500m和碳酸盐补偿深度(Carbon Compensation Depth;CCD)以下,水深大于3500m。在水深0-200m时iGDGTs与水深呈现线性关系,在1000-3500m随着水深梯度增加iGDGT-2逐渐增加和iGDGT-3的减少,此结果与前人在地中海地区研究结果一致。然而在水深大于3500m时,iGDGTs的不同组分均发生了突变,其中TEX86H指标数值增加0.06,意味着其所反映的年均温产生4°C的偏差。我们推测可能是由于在CCD以下碳酸盐物质的大量溶解,导致CO2浓度升高和pH的降低导致微生物群落发生变化导致。同样CCD的变化对古菌OH-GDGT-0,1两类化合物产生影响,但是OH-GDGT-2未受到影响,此结果导致RIOH指标产生影响。随后我们对南海地区基于三类生物标志化合物古温度进行重建,在研究过程中发现源自OH-GDGTs的RIOH指标研究中采用了两种不同的实验方法,超声萃取法和Bligh-Dyer方法。为了研究实验方法是否会影响RIOH作为古温度重建的结果,我们首先对于萃取方法进行了分析。结果表明两种方法对于OH-GDGTs的萃取效率存在系统性差异,同时Bligh-Dyer法提取的OH-GDGTs构建的温度指标与实测温度之间的相关性明显优于超声萃取法。因此我们选择Bligh-Dyer法对OH-GDGTs化合物进行萃取。随后对于三种温度指标与实测温度之间的关系进行分析研究,结果表明:(1)LDI指标在南海地区并不适用,随后对其环境因子进行RDA分析,结果表明可能是由于夏季温度太高导致黄绿藻不生长,LDI可能指示生长温度季节的温度;(2)TEX86H温度指标在南海地区的使用受到其他因素的限制,同样通过对环境因子进行RDA分析,结果表明水深(尤其是CCD以下)可能是限制其在南海地区作为温度指标的一个重要因素;(3)对于OH-GDGTs的研究结果表明在南海地区OH-2/OHs比RIOH与温度的相关性更好,更适合作为古温度指标,因此我们重建了南海地区OH-2/OHs的温度公式,但是需要更多不同地区的样品进行校正。
[Abstract]:In this paper, the surface sediments of the South China Sea China as the research object, signs of long chain glycol on from marine algae and the main source of marine Archaea in compound glycerin two alkyl glycerol ether (four glycerol dialkyl glycerol tetrethers, GDGTs) were studied, focusing on the applicability of the paleo temperature index of corresponding compound construction in the South China Sea area changes. The LDI index which originate long-chain glycol very well in the global range can reflect the temperature, but the research in the South China Sea area has not yet been carried out; the use of TEX86 temperature indicator originated from ancient bacteria in the South China Sea area in unclear instructions, a good solution to reflect the subsurface temperature or seasonal temperature the problem has not yet been; in addition to the new OH-GDGTs compounds found in recent years in the RIOH and OH-2/OHs index in the low latitude ocean can also indicate a change in temperature is very good, but Is due to the particularity of the South China Sea area, it is necessary to further research. Therefore this paper comprehensive study of the above three types of biomarker distribution of compounds in the South China Sea area and its response to temperature, trying to resolve the various biomarkers in the South China Sea area use condition and related factors. Previous studies showed that the distribution of Archaea iGDGTs under the influence of water depth, the ocean deep water carbonate compensation depth will have an effect on the distribution of Archaea GDGTs, we have conducted in-depth study. The results show that the GDGTs distribution with the changes of water depth can be divided into three different interval 0-200m, 1000-3500m and carbonate compensation depth (Carbon Compensation Depth; CCD) the following iGDGTs, the water depth more than 3500m. at a depth of 0-200m and 1000-3500m in depth show a linear relationship, with the increase of iGDGT-2 by water depth gradient Decreased and iGDGT-3 increased gradually, with the result of previous research results in the Mediterranean region. However, at a depth of more than 3500m, the different components of iGDGTs had a mutation, the TEX86H index increased 0.06, mean annual temperature reflecting the 4 DEG C deviation. We speculated that it might be due to the a lot of dissolved carbonate material below CCD, which leads to the decrease of CO2 concentration and pH lead to microbial community changes lead to changes in the same CCD. Influence of archaeal OH-GDGT-0,1 two compounds, but the OH-GDGT-2 is not affected, the resulting effect of RIOH index. Then we in the South China Sea area of three kinds of biological markers for the reconstruction of paleo temperature based on the compound, in the course of the study found that the study of RIOH from OH-GDGTs using two different experimental methods, ultrasonic extraction method and Bligh-Dyer method in order to study. Experimental methods will affect RIOH as palaeoreconstructions results, we first for the extraction methods were analyzed. The results show that the two methods for the systematic difference between the extraction efficiency of the OH-GDGTs, between the temperature index and the measured temperature and the Bligh-Dyer method to extract OH-GDGTs constructed correlation is better than ultrasonic extraction method. So we choose Bligh-Dyer method extraction of OH-GDGTs compounds. Then the relationship between the three kinds of temperature index and measured temperature were analyzed. The results show that: (1) the LDI index is not applicable in the South China Sea area, then the environmental factors RDA analysis, results may be due to the summer temperature is too high resulting in yellow green algae growth, LDI growth may indicate the temperature of the seasonal temperature; (2) using the TEX86H temperature index in the South China Sea area restricted by other factors, the environment for the same Sub RDA analysis results show that the water depth (below CCD) may be the limit in the South China Sea region as an important factor in temperature index; (3) the OH-GDGTs results show that in the South China Sea area OH-2/OHs is better than the correlation between RIOH and temperature, more suitable as the ancient temperature index, so we reconstructed the temperature formula the South China Sea area OH-2/OHs, but need more samples in different regions were corrected.

【学位授予单位】：中国地质大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P532

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