中文摘要：

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。

英文摘要：

Lipid biomarkers have been widely used to reconstruct paleoenvironment and paleoclimate.Biomarker carbon isotopic characteristic（13C）has been a powerful tool to provide information on their precursors,enviromental temperature and moisture.In China,the study on the source implication of individual lipid biomarker stable carbon isotopic characteristics has limited applications in river systems.The focus of this study is the Yellow River（YR）.12near-surface suspended particulate matter samples were collected near the Lijing Station,~50km upstream of the river mouth（Lijin）,as part of a sampling campaign between June 2011 and July 2013 in order to assess seasonal variations in fluvial supply of organic matter（OM）.In addition to bulk properties,the abundance andδ13C of lipid biomarkers（n-fatty acid n-alkanes）were measured.On the molecular 13^ C level,we constraint the origin of various lipid biomarkers in YR,which show contrasting 13 ^C characteristics.Theδ13C values of long chain n-alkanes showed higher values in winter and spring and lower values in summer and fall.Furthermore,δ13^ C of long chain n-alkanes inversely correlated with CPIΣ25~33 values,pointing to a wideδ13 C range of fossil organic components,likely derived from erosion of ancient sedimentary rocks and numerous coal mines along YR.Long chain fatty acids in YR exhibit relatively uniform 13 ^C values and low CPIΣ24~32 values,with range of-31.4‰to-32.1‰ and-31.1‰to-32.2‰respectively,illustrating a highly refractory and C3 plant derived soil OM in north part of China.Theδ13^C values of short chain n-alkanes（n-C17）show significant seasonal variation and distinct aquatic algae signal（-36‰~-40‰）in the summer and autumn.However,δ13^C of short chain fatty acids（n-C16、n-C18）reflect strongly enriched 13 C heterotrophic microbial source contribution.