Alkenones and alkenes in surface waters and sediments of the Southern Ocean: Implications for paleotemperature estimation in polar regions
Alkenones and alkenes in surface waters and sediments of the Southern Ocean: Implications for paleotemperature estimation in polar regions
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DOI：
10.1016/s0016-7037(97)00017-3
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发表时间：
1997-04
影响因子：
5
通讯作者：
E. Sikes;J. Volkman;L. Robertson;J. Pichon
中科院分区：
文献类型：
--
作者：
E. Sikes;J. Volkman;L. Robertson;J. Pichon
测定了南大洋副极地沃茨表层水和表层沉积物样品中C37-C39长链烯酮和烯烃的浓度。这些化合物在两个样品组中的分布相似，表明化合物类别之间或内部的降解差异很小。对于低于6°C的温度，三至四不饱和C37烯酮的相对量随着温度的增加而增加，类似于二和三不饱和C37烯酮。C37的二、三和四不饱和甲基烯酮通过U37 K和U37 K比率用于古温度计算。在这些数据集中，C37：2和C37. 3烯酮的相对丰度与温度的相关性相反，但C37：4烯酮的相对丰度与温度无关。铀37 K的原始定义包括分子和分母的丰度为37：4，因此，在低温下铀37 K的数值存在相当大的分散性可能并不奇怪。在这两个参数中，我们认为U37 K ′是更好的参数，用于古温度估计，即使在寒冷的位置。沉积物中的U37 K ′值实际上落在Sikes和Barkman（1993）的水柱样品中获得的相同回归线上，表明其校准适用于南大洋沉积物。水柱数据与沉积温度估计的比较表明，烯酮分布占主导地位的贡献，从夏天时，Emiliania huxleyi的生物量和大概通量的沉积物，预计将是高的。
The concentration of C37-C39 long-chain alkenones and alkenes were determined in surface water and surface sediment samples from the subpolar waters of the Southern Ocean. Distributions of these compounds were similar in both sample sets indicating little differential degradation between or within compound classes. The relative amounts of the tri- to tetra-unsaturated C37alkenones increased with increasing temperature for temperatures below 6°C similar to the di- and tri-unsaturated C37alkenones. The C37di-, tri-, and tetra-unsaturated methyl alkenones are used in paleotemperature calculations via the U37Kand the U37Kratios. In these datasets, the relative abundances of the C37:2and the C37.3alkenones as a proportion of the total C37alkenones were opposite and strongly related to temperature (the latter with more scatter), but the abundance of the C37:4 alkenone showed no relationship with temperature. The original definition of U37Kincludes the abundance of 37:4 in both the numerator and denominator, and thus it is perhaps not surprising that there is considerable scatter in the values obtained for U37Kat low temperatures. Of the two, we suggest that U37K′is the better parameter for use in paleotemperature estimations, even in cold locations. U37K′values in the sediments fall on virtually the same regression line obtained for the water column samples of Sikes and Volkman (1993), indicating that their calibration is suitable for use in Southern Ocean sediments. The comparison of water column data with sedimentary temperature estimates suggests that the alkenone distributions are dominated by contributions from the summer when the biomass of Emiliania huxleyi and presumably flux to the sediment, is expected to be high.