长江口外藻类生物标志化合物氢同位素与海洋盐度关系的研究

Compound-specific hydrogen isotope (δD) of biomarker is a promising tool in paleohydrological and paleoenvironment research in recent years. However, investigation about the controlling factors of lipids’ δD in marine environment is still very limited. To advance our understanding of this issue, we apply for this new research. In this study, we intend to collect sea water, suspended particles, and surface sediment samples along salinity sections off Yangtze Estuary, which would be vertical to salinity gradient and current direction, then extract biomarkers including sterols, alkenones and fatty acids from them, followed by determine their δD (δ13C) values. Combining with the δD and salinity of sea surface water data, we will explore and construct the relationship between δD values, hydrogen isotope fractionation in alga biomarkers and salinity, and provide basic data and evidence for the application of biomarker δD in paleohydrological and paleoceanographic study.

生物标志化合物单体氢同位素作为一种较新的研究手段，近年来在古水文古环境的研究中突显出巨大的应用潜力。但目前海洋环境中脂类氢同位素的影响控制因素的研究相对薄弱。本项目拟以分子有机地球化学结合分子单体稳定同位素测试为手段，采集长江口外垂直于盐度梯度和海流方向断面的水体悬浮颗粒物和表层沉积物，提取甾醇类、长链烯酮和脂肪酸等海洋藻类生物标志化合物，测定其分子单体稳定氢（碳）同位素。在此基础上，结合海水盐度和氢同位素等资料，探讨和建立海洋藻类生物标志化合物氢同位素及其分馏程度与海水盐度的对应关系，为生物标志物单体氢同位素在古水文古海洋研究中的正确应用提供数据依据和理论基础。

海洋藻类生物标志物氢同位素（δD）被认为可以做为古表层海水盐度（SSS）重建参数。本项目利用长江口外典型盐度梯度断面的季节性样品，以脂类生物标志物为手段，结合单体氢同位素测试技术，探讨海洋藻类生标氢同位素和表层海水盐度的经验关系，得出以下主要结论：长江口外藻类生标含量的时空分布能较好地反映区域藻类生物量，夏季菜籽甾醇和甲藻甾醇的含量较高；表层沉积物中的甲藻甾醇和颗粒物中的菜籽甾醇的氢同位素值与表层海水盐度存在显著的正相关关系，显示出较强的古盐度重建潜力。