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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Widespread occurrence of distinct alkenones from Group I haptophytes in freshwater lakes: Implications for paleotemperature and paleoenvironmental reconstructions
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Widespread occurrence of distinct alkenones from Group I haptophytes in freshwater lakes: Implications for paleotemperature and paleoenvironmental reconstructions

机译：在淡水湖泊中，我患有I族的不同链烯酮的普遍发生：对古温度和古环境重建的影响

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Alkenones are C35-C42 polyunsaturated ketone lipids that are commonly employed to reconstruct changes in sea surface temperature. However, their use in coastal seas and saline lakes can be hindered by species-mixing effects. We recently hypothesized that freshwater lakes are immune to species-mixing effects because they appear to exclusively host Group I haptophyte algae, which produce a distinct distribution of alkenones with a relatively consistent response of alkenone unsaturation to temperature. To evaluate this hypothesis and explore the geographic extent of Group I haptophytes, we analyzed alkenones in sediment and suspended particulate matter samples from lakes distributed throughout the mid- and high latitudes of the Northern Hemisphere (n = 30). Our results indicate that Group I-type alkenone distributions are widespread in freshwater lakes from a range of different climates (mean annual air temperature range: -17.3-10.9 degrees C; mean annual precipitation range: 125-1657 mm yr(-1); latitude range: 40-81 degrees N), and are commonly found in neutral to basic lakes (pH 7.0), including volcanic lakes and lakes with mafic bedrock. We show that these freshwater lakes do not feature alkenone distributions characteristic of Group II lacustrine haptophytes, providing support for the hypothesis that freshwater lakes are immune to species-mixing effects. In lakes that underwent temporal shifts in salinity, we observed mixed Group I/II alkenone distributions and the alkenone contributions from each group could be quantified with the RIK37 index. Additionally, we observed significant correlations of alkenone unsaturation (U-37(K)) with seasonal and mean annual air temperature with this expanded freshwater lakes dataset, with the strongest correlation occurring during the spring transitional season (U-37(K) = 0.029 * T - 0.49; r(2) = 0.60; p 0.0001). We present new sediment trap data from two lakes in northern Alaska (Toolik Lake, 68.632 degrees N, 149.602 d
机译：链烯酮是C35-C42多不饱和酮脂质，其通常用于重建海表面温度的变化。然而，他们在沿海海和盐水湖泊的使用可以通过物种混合效果阻碍。我们最近假设淡水湖泊对物种混合效果免疫，因为它们似乎仅宿主群I族斑藻，其产生了与烷烃不饱和度的相对一致的乳糖酮的分布。为了评估该假设并探讨I族的地理范围，我们在北半球（N = 30）的整个中和高纬度地区的湖泊中分析了沉积物中的盐酸烯酮和悬浮的颗粒物样品（n = 30）。我们的研究结果表明，I型链烯酮分布在淡水湖泊中，来自一系列不同气候的淡水湖泊（平均空气温度范围：-17.3-10.9摄氏度;平均年降水量：125-1657 mm YR（-1）;纬度范围：40-81°N），并且通常在中性到基本湖泊（pH＆ 7.0）中，包括火山湖泊和湖泊与MAFIC基岩。我们表明，这些淡水湖泊不具有II族曲线驼背族的链烯酮分布，为淡水湖泊免受物种混合效应的假设提供支持。在湖泊中经历盐度的颞叶，我们观察到混合群I / II链烯酮分布，每组的链烯酮贡献可以用RIK37指数量化。此外，我们观察到链烯酮不饱和度（U-37（k））与季节性和平均年度空气温度的显着相关性与该膨胀的淡水湖数据集，在春季过渡季节期间发生的最强相关性（U-37（k）= 0.029 * t - 0.49; r（2）= 0.60; p <0.0001）。我们从阿拉斯加北部的两个湖泊出现了新的沉积物陷阱数据（Toolik Lake，68.632度N，149.602 D.

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