Temperature calibration and phylogenetically distinct distributions for freshwater alkenones: Evidence from northern Alaskan lakes
Temperature calibration and phylogenetically distinct distributions for freshwater alkenones: Evidence from northern Alaskan lakes
复制标题
DOI：
10.1016/j.gca.2016.02.019
复制
发表时间：
2016-05
影响因子：
5
通讯作者：
W. Longo;S. Theroux;A. Giblin;Yinsui Zheng;J. T. Dillon;Yongsong Huang
中科院分区：
文献类型：
--
作者：
W. Longo;S. Theroux;A. Giblin;Yinsui Zheng;J. T. Dillon;Yongsong Huang
烯酮是一类不饱和长链酮生物标志物，已被用于重建海洋表面温度，最近，大陆温度，通过烯酮不饱和指数（如U 37 K和U 37 K′）。烯酮是经常发现在半咸水和咸水湖泊，但物种的影响混淆温度重建时，多个烯酮生产的物种具有不同的温度响应。有趣的是，现有的遗传数据表明，许多淡水湖泊宿主的独特的单细胞型的烯酮生产的附着藻类（组I或格陵兰岛的单细胞型），提供证据表明，物种的影响可能会减少在淡水湖泊。这些发现鼓励进一步研究在淡水系统中的烯酮古温度代理。在这里，我们调查了湖泊从北方阿拉斯加（n= 35），并表明，烯酮通常发生在淡水湖泊，在那里他们的特点是不同的分布，其特点是占主导地位的C 37：4烯酮和一系列的三不饱和烯酮异构体。这些分布是以前在格陵兰和北美发现的I组型烯酮分布的特征。我们对图里克湖（68° 38′ N，149° 36′ W）悬浮颗粒物的分析首次获得了现场淡水U 37 K校准（U 37 K= 0.021* T− 0.68; r 2= 0.85; n= 52; RMSE=±1.37° C）。我们探讨了三不饱和异构体的环境意义，使用我们的北方阿拉斯加湖泊数据集结合新的数据从附着植物文化和加拿大的表层沉积物。我们的研究结果表明，这些温度敏感的异构体是生物标志物的第一组的类型和指标的多物种的影响。总之，这些研究结果突出了淡水湖泊作为大陆烯酮为基础的古温度重建的有价值的目标，并证明了最近发现的三不饱和异构体的意义。
Alkenones are a class of unsaturated long-chain ketone biomarkers that have been used to reconstruct sea surface temperature and, more recently, continental temperature, by way of alkenone unsaturation indices (eg U 37 K and U 37 K′). Alkenones are frequently found in brackish and saline lakes, however species effects confound temperature reconstructions when multiple alkenone-producing species with different temperature responses are present. Interestingly, available genetic data indicate that numerous freshwater lakes host a distinct phylotype of alkenone-producing haptophyte algae (the Group I or Greenland phylotype), providing evidence that species effects may be diminished in freshwater lakes. These findings encourage further investigation of alkenone paleotemperature proxies in freshwater systems. Here, we investigated lakes from northern Alaska (n= 35) and show that alkenones commonly occurred in freshwater lakes, where they featured distinct distributions, characterized by dominant C 37: 4 alkenones and a series of tri-unsaturated alkenone isomers. The distributions were characteristic of Group I-type alkenone distributions previously identified in Greenland and North America. Our analysis of suspended particulate matter from Toolik Lake (68° 38′ N, 149° 36′ W) yielded the first in situ freshwater U 37 K calibration (U 37 K= 0.021* T− 0.68; r 2= 0.85; n= 52; RMSE=±1.37° C). We explored the environmental significance of the tri-unsaturated isomers using our northern Alaskan lakes dataset in conjunction with new data from haptophyte cultures and Canadian surface sediments. Our results show that these temperature-sensitive isomers are biomarkers for the Group I phylotype and indicators of multiple-species effects. Together, these findings highlight freshwater lakes as valuable targets for continental alkenone-based paleotemperature reconstructions and demonstrate the significance of the recently discovered tri-unsaturated isomers.