长链烯酮在西北大西洋重建全新世气候变化的研究进展

Progress in using the long-chain alkenones to reconstruct the Holocene climate changes in northwest Atlantic Ocean

大量研究表明,长链烯酮不饱和度(U^(K’)_(37)指数)可用于重建过去的海面温度(sea surface temperature,SST),然而是否存在其他因素导致实际温度与重建的SST之间存在差异,以及重建的温度是代表年均SST还是季节性温度都仍有争议。除了反映温度,在受季节性海冰影响或SST较低的区域,长链烯酮C_(37:4)在C_(37)中的占比(%C_(37:4))还能为盐度变化提供重要信息,特别是在拉布拉多和格陵兰岛陆地边缘海域。在此总结了西北大西洋长链烯酮重建古海洋气候的研究进展,指出了在使用U^(K’)_(37)重建SST时,需要考虑营养盐、横向平流、成岩作用以及烯酮母源的生长季节性等因素,认为%C_(37:4)有望用作重建过去海冰融水或海冰覆盖情况的替代指标,但季节性因素对烯酮重建古温的影响程度的评估还需要进一步研究。

Numerous studies have demonstrated the application of long-chain alkenone unsaturation ratios(U^(K’)_(37))to reconstruct past sea-surface temperatures(SSTs).However,whether there are factors resulting in divergence between the actual and reconstructed sea-surface temperatures and whether the reconstructed temperature or the seasonal temperature represents the annual average SST have remained controversial.In regions influenced by seasonal sea-ice or low SSTs,the proportion of long-chain alkenone C_(37:4) in C_(37)(i.e.,%C_(37:4))provides significant information on salinity,particularly on the Labrador and Greenland continental margin.This study reviews the progress of usingU^(K’)_(37)in the northwest Atlantic Ocean and evaluates factors,including nutrient,lateral advection,early diagenesis,and seasonality of the production of alkenone-producing algae,to reconstruct SSTs.Our results suggest that C_(37:4) can reconstruct past sea-ice released meltwater and sea-ice cover;however,quantifying the contribution of the U^(K’)_(37)seasonality needs further study.