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湖泊沉积物中甘油二烷基甘油四醚化合物(GDGTs)在记录陆地古气候方面有着重要作用.然而,这些化合物,尤其是细菌支链GDGTs(bGDGTs)异构体(5-,6-甲基bGDGTs)在中国不同酸碱性湖泊中的分布及其影响因素仍未可知.本文通过对碱酸度不同的湖泊进行对比,并结合其他环境变量,调查了GDGTs各类化合物在中国中东部湖泊系统和西南酸性青海中的分布特征及其影响因素.结果表明,湖水含氧量能够影响湖泊古菌群落结构,从而影响古菌iGDGTs的分布.GDGT-0/crenarchaeol比值随着含氧量降低而增高,表明厌氧的产甲烷古菌或混杂型泉古菌(MCG)与奇古菌相对含量受控于湖水含氧量.含氧量较低的湖泊奇古菌贡献GDGTs化合物比例较小,四醚指数TEX_(86)不能用来重建表层湖水温度.与土壤不同的是,湖水pH并不会影响古菌iGDGTs和细菌bGDGTs的相对含量,但在单一湖泊,如腾冲青海中,古菌与细菌的相对含量(R_(ilb))与水深相关.虽然这些湖泊中细菌bGDGTs的甲基化指数(MBT’)与年均大气温度(MAT)和pH(或年均降雨量)相关,环化指数(CBT)仅与pH相关,但基于5-甲基bGDGTs的MBT’_(5ME)与MAT的关系并不明显,反而是表征6-甲基bGDGTs甲基化程度的MBT’_(6ME)与MAT更相关.与全球土壤相似,湖泊中5-,6-甲基bGDGTs的相对含量也主要受pH影响.因此,6-甲基bGDGTs的相对含量(IR)或CBT’可以作为潜在的湖泊pH计.但在较小pH梯度下,IR和CBT’两个指标可能受其他环境因子,如温度等的影响.
Glycerol dialkylglycerol tetraether compounds (GDGTs) in lake sediments play an important role in the recording of paleoclimate on the terrestrial land. However, these compounds, especially the bacterial branched GDGTs (5-6-methyl the distribution of bGDGTs in different acid-alkaline lakes in China and its influential factors are still unknown.Through comparing the different acidity lakes and combining with other environmental variables, we investigated the effects of various GDGTs on the lake systems in central and eastern China, Distribution characteristics and influencing factors in sour southwest of Qinghai.The results show that the oxygen content in lake can affect the archaeal community structure of archaea and thus affect the distribution of archaea iGDGTs.GDGT-0 / crenarchaeol ratio increases with the decrease of oxygen content, The results showed that the relative contents of anaerobic methanotrophic archaebacteria or mixed quacker (MCG) and archaea were controlled by the lake water oxygen content.The archaea in the lower oxygen content of GDGTs contributed a smaller proportion of tetrachlorethylene The index TEX_ (86) can not be used to reconstruct the surface water temperature. Unlike soil, lake pH does not affect the relative content of archaeal iGDGTs and bacterial bGDGTs, but in a single lake, such as the Tengchong Qinghai Sea, archaeal and bacterial relatively The amount (R_ (ilb)) is related to water depth, and although the methylation index (MBT ’) of bacterial bGDGTs in these lakes is related to the mean annual temperature (MAT) and pH ) Is only related to pH, but MBT’_ (5ME) based on 5-methyl bGDGTs is not obvious to MAT, but MBT’_ (6ME) and MAT, which characterize the degree of methylation of 6-methyl bGDGTs, The relative content of 5- and 6-methyl bGDGTs in lakes is also mainly affected by pH, similar to global soils, so the relative content (IR) of 6-methyl bGDGTs or CBT ’can be used as a potential lake pH meter. However, at a small pH gradient, both IR and CBT ’indicators may be affected by other environmental factors, such as temperature.