New insights into environmental controls on the occurrence and abundance of Group I alkenones and their paleoclimate applications: Evidence from volcanic lakes of northeastern China
New insights into environmental controls on the occurrence and abundance of Group I alkenones and their paleoclimate applications: Evidence from volcanic lakes of northeastern China
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第一类烯酮的出现和丰度的环境控制及其古气候应用的新见解：来自中国东北火山湖的证据
DOI：
10.1016/j.epsl.2019.115792
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发表时间：
2019
影响因子：
5.3
通讯作者：
Huang Yongsong
中科院分区：
文献类型：
--
作者：
Yao Yuan;Zhao Jiaju;Longo William M;Li Gaoyuan;Wang Xian;Vachula Richard S;Wang Karen J;Huang Yongsong
淡水和寡盐湖泊中等鞭金藻目植物产生的独特的长链烯酮（LCAs）在定量古温度重建方面具有很大的潜力。然而，由于对淡水湖泊中I组LCAs发生的环境控制的不完全了解，I组沉积LCAs的广泛应用受到阻碍。在北方阿拉斯加淡水湖中I组LCA浓度和pH（6.2-8.5）之间的对应关系（Longo等人，2016）表明，第I组等鞭金藻目可能优先在高pH值的淡水湖泊中茁壮成长。在这里，我们系统地研究了中国东北18个淡水火山湖的LCA分布，附着菌特异性18 S rDNA序列，以及主要离子和微量元素的浓度，pH值范围从7.17到9.99。我们发现，18个湖泊中有11个含有I组LCA及其生产者的相应DNA序列。我们的DNA结果表明，在所有11个湖泊中的主要烯酮生产商是密切相关的第一组格陵兰OTU 5基因型，除了两个undergenically影响的湖泊，其中少量的第二组sequencesfounded. Statistical分析表明，浓度最高的第一组LCAs被发现在贫营养淡水湖泊的pH值范围从10.7.3至8.8。我们发现，某些微量元素的浓度升高可能会导致消失的第一组LCAs，尽管湖水落入最佳pH值范围内。与先前发表的来自北方淡水湖温度校准的I组LCA数据一起（Longo等人，2018年），我们首次发现，当冬季平均温度高于20° C时，第一组R3 b（R3 b = C 37：3b/（C 38：3b Et+ C 37：3b））值对冬季温度变化最敏感。我们的研究结果表明，淡水火山湖在中国东北地区是非常有价值的目标，古温度重建使用第I组LCA。
The distinctive long-chain alkenones (LCAs) produced by Group I Isochrysidales from freshwater and oligohaline lakes have great potential for quantitative paleotemperature reconstructions. The widespread application of sedimentary Group I LCAs, however, is hampered by an incomplete understanding of the environmental controls on the occurrence of Group I LCAs in freshwater lakes. The correspondence between Group I LCA concentrations and pH (6.2–8.5) in northern Alaskan freshwater lakes (Longo et al., 2016) suggests that Group I Isochrysidales may preferentially thrive in freshwater lakes with high pH. Here, we systematically study LCA distributions, haptophyte-specific 18S rDNA sequences, and concentrations of major ions and trace elements in 18 freshwater volcanic lakes in northeastern China with an extended pH range from 7.17 to 9.99. We find that 11 of the 18 lakes examined contain Group I LCAs and the corresponding DNA sequences of their producers. Our DNA results indicate that the dominant alkenone producer in all 11 lakes is closely related to the Group I Greenland OTU 5 genotype, with the exception of two anthropogenically impacted lakes where small numbers of Group II sequences are found. Statistical analyses indicate that the highest concentrations of Group I LCAs are found in oligotrophic freshwater lakes with pH ranging from∼ 7.3 to 8.8. We find that elevated concentrations of certain trace elements may lead to the disappearance of Group I LCAs despite lake water falling within the optimal pH range. Together with previously published Group I LCA data from the temperature calibration in Northern Hemisphere freshwater lakes (Longo et al., 2018), we find, for the first time, that Group I R3b (R3b= C 37: 3b/(C 38: 3b Et+ C 37: 3b)) values are most sensitive to winter temperature changes when mean winter temperature is higher than∼− 20° C. Our results suggest that the freshwater volcanic lakes in northeastern China are highly valuable targets for paleotemperature reconstructions using Group I LCAs.