Climatic and Environmental Controls on the Occurrence and Distributions of Long Chain Alkenones in Lakes of the Interior United States
Climatic and Environmental Controls on the Occurrence and Distributions of Long Chain Alkenones in Lakes of the Interior United States
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DOI：
10.1016/j.gca.2009.11.021
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发表时间：
2010-03
影响因子：
5
通讯作者：
J. Toney;Y. Huang;S. Fritz;P. A. Baker;E. Grimm;P. Nyren
中科院分区：
文献类型：
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作者：
J. Toney;Y. Huang;S. Fritz;P. A. Baker;E. Grimm;P. Nyren
长链烯烃（LCA）是一种对温度敏感的脂质，在定量重建过去大陆气候方面具有很大的潜力。我们对美国北部大平原和内布拉斯加州沙山55个不同湖泊的烯酮生物标志物进行了首次调查。在调查的湖泊中，我们发现13个湖泊在地表沉积物中含有LCAs。沉积物中烯酮的最高浓度出现在具有高浓度钠和硫酸盐的寒冷湖泊（年平均气温为11°C，而最温暖的地区为17°C）、半咸水至中咸水湖泊（盐度= 8.5-9.7g /L）和碱性湖泊（pH= 8.4-9.0）。分层动态和养分有效性似乎也在LCA丰度中发挥作用，因为早春混合促进了产生烯酮的共生植物的开花。四个含烯酮的位点含有c37:4烯酮；然而，我们在一组湖泊中发现了一个前所未有的湖相烯烃分布，完全没有c37:4烯烃。我们将这种不寻常的组成归因于不同的触生植物物种，并表明硫酸盐：碳酸盐的比例可能控制这两个不同种群的发生。我们对含有c37:4的湖泊站点使用来自乔治湖的水柱校准创建了一个新的原位温度校准，并表明U37Kis与湖泊水温线性相关（R2=0.74），但[公式：见文本]不是。许多湖泊含有一种未识别的化合物系列，它在lca附近被洗脱，这突出了在使用湖泊lca进行古温度重建之前进行常规GC-MS检查的重要性。
Long chain alkenones (LCA) are temperature-sensitive lipids with great potential for quantitative reconstruction of past continental climate. We conducted the first survey for alkenone biomarkers from 55 different lakes in the Northern Great Plains and Nebraska Sand Hills of the United States. Among those surveyed, we found 13 lakes that contain LCAs in the surface sediments. The highest concentrations of alkenones in sediments are found in cold (mean annual air temperature ∼11°C versus 17°C in our warmest sites), brackish to mesosaline (salinity=8.5–9.7g/L), and alkaline (pH=8.4–9.0) lakes with high concentrations of sodium and sulfate. The dynamics of stratification and nutrient availability also appear to play a role in LCA abundance, as early spring mixing promotes a bloom of alkenone-producing haptophytes. Four of the alkenone-containing sites contain the C37:4alkenone; however, we discovered an unprecedented lacustrine alkenone distribution in a cluster of lakes, with a total absence of C37:4alkenone. We attribute this unusual composition to a different haptophyte species and show that the sulfate:carbonate ratio may control the occurrence of these two distinct populations. We created a new in-situ temperature calibration for lacustrine sites that contain C37:4using a water-column calibration from Lake George, ND and show that U37Kis linearly correlated to lake water temperature (R2=0.74), but [Formula: see text] is not. A number of lakes contain an unidentified compound series that elutes close to the LCAs, highlighting the importance of routine GC–MS examination prior to using lacustrine LCAs for paleotemperature reconstructions.