Calibration of alkenone unsaturation ratios (Uk'37) for paleotemperature estimation in cold polar waters
Calibration of alkenone unsaturation ratios (Uk'37) for paleotemperature estimation in cold polar waters
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DOI：
10.1016/0016-7037(93)90120-l
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发表时间：
1993-04
影响因子：
5
通讯作者：
E. Sikes;J. Volkman
中科院分区：
文献类型：
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作者：
E. Sikes;J. Volkman
摘要/ Abstract摘要：在澳大利亚南部南大洋温度范围为0.7 ~ 12.2°C的地表水颗粒有机物样品中鉴定出了c37 ~ c39不饱和酮（烯酮）和烯烃。碳数分布表明，这些化合物来源于原体藻赫胥黎Emiliania huxleyi，该藻是该水域主要的球粒藻。根据定义U k'37=[37: 2]（[37: 2]+[37: 3]）计算U k'37的值，其中[37:x]是带有“x”双键的c37烯酮的浓度，并根据海表温度（SST）绘制。我们的数据与早先从温暖水域收集的数据形成了一个连续的集合。在大部分温度范围内，U k'37与温度之间的关系是显著的线性关系，并且最适合用简单的公式U k'37= 0.0414T-0.156（温度为4-25°C）。在野外样品中对uk37的温度校准与在培养中对原体藻进行的分析有很大的不同，特别是在较冷的温度下。温度低于约4-6°C的数据显示散射增加，在这些低温下的校准可能更适合非线性指数函数，但这需要进一步的测试。当然，线性校准的预测能力在低于5.0°C的温度下受到严重限制，但在高于5.0°C的温度下，我们的数据确定了uk '37作为南大洋极地锋以北水域和世界海洋几个地区的海温指标的有效性。
Abstract C 37–C 39 long-chain unsaturated ketones (alkenones) and alkenes were identified in samples of particulate organic matter obtained from surface waters spanning the temperature range-0.7–12.2° C in the Southern Ocean south of Australia. The carbon number distribution indicates that these compounds are derived from the prymnesiophyte alga Emiliania huxleyi which is the predominant coccolithophorid in these waters. Values of U k'37 were calculated according to the definition U k'37=[37: 2]([37: 2]+[37: 3]), where [37: x] is the concentration of the C 37 alkenone with “x” double bonds, and plotted against sea surface temperature (SST). Our data form a contiguous set with earlier compilations of data from warmer waters. Over much of the temperature range the relationship between U k'37 and temperature is remarkably linear, and is best fitted by the simple equation U k'37= 0.0414T—0.156 (for temperatures 4–25° C). This calibration of U k'37 with temperature for field samples is significantly different from that established from analyses of prymnesiophyte algae in culture, and it diverges especially at the colder temperatures. Data for temperatures below about 4–6° C show increased scatter and the calibration at these low temperatures may be better fitted by a nonlinear exponential function, but this requires further testing. Certainly, the predictive power of the linear calibration is severely constrained at temperatures less than 5.0° C, but at temperatures above this our data establish the usefulness of U k'37 as an SST indicator for waters north of the polar front in the Southern Ocean and for several regions of the world ocean.