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Lipid biomarkers widely dotted in marine sediments, as their distribution characteristics accurately record huge information on the metabolism of the original organisms and migration and transformation of these organic components, are often used to reconstruct the paleoclimatic and paleoenvironmental conditions. This paper reviewed the progress in the study of paleoclimatic-environmental changes during the late Quaternary using abundant core lipids Glycerol Dialkyl Glyceryl Tetraethers (GDGTs) and long-chain alkyl diols in marginal sea sediments. It is pointed out that clarifying the “source-sink” process of lipid biomarkers buried in marine sediments is a prerequisite for paleoclimatic-environmental reconstruction. It is believed that the use of multiple indicators that are less affected by early diagenesis can increase the accuracy of reconstructing paleoclimatic changes. In the large-river dominated marginal seas, the mechanism of land-sea climate coupling evolution stimulated by the paleoclimatic-environmental changes can be elucidated based on paleoclimatic records reconstructed from core lipids GDGTs and long-chain alkyl diols in marine sediments. It is hoped that this paper can provide reliable technical means and a solid theoretical basis for predicting future temperature and rainfall changes. 相似文献
2.
Long-chain alkyl diols contain an alkyl chain with alcohol groups at C1 and at the middle position of carbon chain, which exist widely in seas, rivers and lakes. It has been proven that these compounds are relatively resistant to degradation and have an extended occurrence in the geological record. In addition, they are relatively easy to identify. Therefore, long-chain alkyl diols can be used as potential biomarkers to trace the past change in paleoenvironment and paleoclimate. Although the sources of long-chain alkyl diols are still uncertain, the studies indicate that 1, 13 and 1, 15-diols are mainly produced by eustigmatophytes, while 14-diols are mainly from diatom Proboscia. So far, some proxies based on long-chain alkyl diols have been established to indicate the change in diatom productivity, upwelling intensity, salinity, sea surface temperature, riverine organic matter input and surface seawater nutrient concentration, which are significant for paleoenvironmental reconstruction. Current research and application of long-chain alkyl diols proxies were summarized, which would be helpful for further studying the source of long-chain alkyl diols and the application of relevant proxies in China’s marginal sea. 相似文献
3.
Combined with quantitative determination of concentration and isotopic composition of petroleum hydrocarbons, weathering simulation experiments on artificially mixed oils and their two end-member oils are performed for identification and quantification of mixed sources. The >C18n-alkanes show no appreciable losses during a short-term weathering process. An approach based on distribution of long-chain n-alkanes (>C18) is suggested for estimating the contribution proportion of each source in mixed oils. Stable carbon isotope profile of individual n-alkanes is a powerful tool to differentiate sources of oil spills, but unavailable to accurately allocate each contribution due to a relatively large analytical error. 相似文献
4.
Sea surface temperature variations in the southwestern South China Sea over the past 160 ka 总被引：1，自引：0，他引：1
Sea surface temperatures (SSTs) in the southwestern South China Sea have been reconstructed for the past 160 ka using the Uk37 paleothermometer from the core MD01-2392. The temperature differences between glacial times (MISs 6 and 2) and interglacial times (MISs 5.5 and 1) are 2.2~2.5 ℃. Younger Dryas event during the last deglaciation was documented in both the planktonic foraminiferal δ18O and SST records. After MIS 5.5, SSTs displayed a progressive cooling from 28.6 to 24.5 ℃, culminating at the LGM. During this gradual cooling period, warm events such as MISs 5.3, 5.1 and 3 were also clearly documented. By comparison of SST between the study core and Core 17954, a pattern of low or no meridional SST gradients during the interglacial periods and high meridional SST gradients during the glacial periods was exhibited. This pattern indicates the much stronger East Asian winter monsoon at the glacial than at the interglacial periods. Spectral analysis gives two prominent cycles: 41 and 23 ka, with the former more pronounced, suggesting that SSTs in the southern SCS varied in concert with high-latitude processes through the connection of East Asian winter monsoon. 相似文献
5.
南海长链烯酮化合物的检测及U37^k值的应用 总被引：3，自引：1，他引：2
首次系统地在南海大面积站位中检测出长链烯酮化合物。通过长链烯酮指标Ｕ３７ｋ与实测表层海水温度（ＳＳＴ）的对比研究,发现海洋沉积物样品在室温下长期（１７ａ）密封保存,长链烯酮指标Ｕ３７ｋ值无明显变化。Ｕ３７ｋ值在南海海区指示的表层海水温度与季节有关,主要反映秋、冬两季,即１０月至次年３月间的ＳＳＴ。 相似文献
6.
长链烷基二醇类化合物(Long-chain alkyl diols)是指在碳链的1号位置和链中位置连接有羟基基团的类脂化合物,普遍存在于海洋、河流和湖泊环境中。由于这类化合物分布广泛、性质稳定不易降解、且检测手段较为简单,因此具有作为生物标志物的潜力,在生物地球化学领域引起了广泛的研究和关注。关于其生物来源尚未有定论,但是研究发现1,13-diols和1,15-diols可能主要来自真眼点藻,而14-diols主要来自硅藻Proboscia。目前根据长链烷基二醇建立的指标包括:硅藻生产力、上升流强度、盐度、温度、河流输入和表层海水营养盐浓度等,对古环境气候的重建有着重要的意义。归纳总结了目前长链烷基二醇指标的研究和应用进展,这有助于未来我国边缘海长链烷基二醇来源以及二醇指标的深入研究。 相似文献
7.
应用生物标志化合物长链烯酮不饱和比值 Uk37估算冲绳海槽 2万年以来古海水表层温度 ,其波动范围在 1 5.9～ 2 6.2℃之间 ,平均为 2 2 .9℃。并与常用的浮游有孔虫转换函数测算的表层海水温度进行对照 ,结果与冬季表层水温 ( 2 2 .0℃ )相近 ,Uk37值指示的古海水温度与季节有关 ,主要反映在冬季。在沉积物中还检出了另一类生物标志化合物甾、萜类等 ,对它们的组成进行了地球化学研究 ,结果表明 :冲绳海槽沉积物中有机质具有多源性特点 ,由陆源碎屑、生物碎屑和火山碎屑共同组成 ;该海域沉积有机质的成熟度不高 ,沉积环境具有强的还原性。 相似文献
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古生产力的精确重建对于了解地质历史时期的碳循环具有非常重要的作用,高分辨率有机地球化学记录在重建古海洋生产力上有独到的优势。基于17个AMS14C年代分析数据,本文分析了冲绳海槽南端MD05-2908孔(24°48.04′N,122°29.35′E)沉积柱状样中的长链不饱和烯酮含量以及物质通量,并结合沉积物有机碳同位素数据恢复评价了南冲绳海槽古海洋生产力的变化。结果显示近7000aB.P.以来南冲绳海槽古生产力存在着显著波动。将海洋古生产力指标与全新世ITCZ南北移动记录的对比分析,发现其变化与ITCZ的南北移动有密切的关系,一方面ITCZ南北移动影响陆源物质的输入,从而改变海洋营养物质的供应状况,造成生产力的高低变化;另一方面,ITCZ南北移动所造成的陆源物质输入冲淡了海洋生产力输入对沉积有机质的贡献,因此在高陆源物质影响区单用生物标志化合物相对有机碳的丰度评价古海洋生产力存在着一定的不可靠性。此外,通过与高纬度气候记录的对比发现,南冲绳海槽海洋生产力的低值变化与北半球高纬度地区的气候冷事件基本一致,显示出高低纬度气候环境变化之间的强相关性。 相似文献
9.
通过对气相色谱仪分析低纬陆架痕量长链烯酮过程中的升温速率和载气流速两个主要条件进行了探讨,对比了不同的程序升温速率和不同载气流量条件下烯酮的分离效果和检测精确度及重现性。研究发现色谱分析条件对低纬度痕量长链烯酮的分析有显著的影响。当前广泛适用于中低纬度开放大洋沉积物样品的较高的程序升温方法难以对低纬度高陆源物质冲淡作用影响下的陆架海沉积物样品进行有效的分离分析。在接近U3K7′指标适用温度上限且C37∶3烯酮含量极低的情况下(1ng/g干样,计算温度接近27℃),采用较低的程序升温速率分离C37∶3和C37∶2及后续化合物有利于获得良好的分离效果,且分析的精确度和重现性较之高的升温速率好。在对痕量且接近温度适用极限的烯酮样品进行分析时,应采用相对较小的载气流量以便获得理想的分离度和更加精确的分析结果。 相似文献
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