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类脂生物标志物是古环境、古气候研究中一类常用的生物标志物,其稳定碳同位素性质能反映母源先质的来源以及温度、湿度等信息。在中国,类脂生物标志物分子稳定碳同位素对母源体的指示意义的研究大多局限于现代表层土壤中且存在区域限制性,河流中的研究工作较少。本研究以黄河为例,自2011年6月~2013年7月期间采集了黄河下游东营站12个表层悬浮颗粒物样品,利用13 C同位素确证了不同类脂生物标志物来源的指示意义。其中长链正构烷烃的δ13 C值在两年调查研究中均呈现冬、春季相对偏正,夏、秋季偏负的季节性变化趋势,且与长链正构烷烃CPI25~33值呈显著的线性负相关,显示了正构烷烃受到偏正的烃源沉积岩贡献。长链脂肪酸(n-C28、n-C30)的δ13 C值无明显的季节性变化,且CPIΣ24~32较低,范围分别为-31.4‰~-32.1‰和-31.1‰~-32.2‰,表明黄河悬浮颗粒物中脂肪酸主要来源于中国北部以C3植被覆盖为主的黄土土壤有机质的贡献,受季节更替新鲜植被源贡献较少。短链n-C17烷烃的δ13 C值季节变化明显,在夏、秋季显示出了明显的偏负的水生藻类源信号,而短链n-C16、n-C18脂肪酸在很大程度上受到δ13 C偏正的水体异养微生物的贡献。
Lipid biomarkers are a kind of commonly used biomarkers in palaeoclimate and paleoclimate research. Their stable carbon isotope characteristics can reflect sources of maternal precursors, temperature, humidity and other information. In China, most of the studies on the indicator significance of the stable carbon isotopes of lipid biomarkers on maternal origin are confined to modern topsoil and have regional restriction, and there are few researches in rivers. Taking Yellow River as an example, 12 surface sediment particles collected from Dongying Station in the lower Yellow River from June 2011 to July 2013 were collected. The 13 C isotopes were used to confirm the origin of different lipid biomarkers. Among them, the δ13C value of long-chain n-alkanes showed a seasonal change trend of relative normality in winter and spring, partial negative in summer and autumn, and significant correlation with the long-chain n-alkanes CPI25-33 The linear negative correlation shows that n-alkanes are contributed by the biased source sedimentary rocks. The δ13C values of long-chain fatty acids (n-C28, n-C30) showed no obvious seasonal changes, and the CPIΣ24-32 values were lower ranging from -31.4 ‰ to -32.1 ‰ and from -31.1 ‰ to -32.2 ‰, respectively The fatty acids in the suspended particulate matter of the Yellow River mainly come from the contribution of organic matter in loess soil dominated by C3 vegetation in the northern part of China, which is less affected by the seasonal vegetation source. The δ13C values of short-chain n-C17 alkanes vary significantly during the seasons, with significant negative aquatic algal source signals being evident in summer and autumn, whereas short-chain n-C16, n-C18 fatty acids are strongly affected by δ13C Conservative contribution of heterotrophic microorganisms in water bodies.