中文摘要：

对黄河口湿地表层土壤中的总有机碳、正构烷烃等进行了分析,计算了正构烷烃分子指标,探讨了其物源指示意义,并对不同采样区域和采样时间的结果进行了比较.结果表明,黄河口湿地土壤中正构烷烃以高碳奇数烷烃（C25～C33）为主,说明土壤中有机质主要来自于陆地高等植物,而样品中未分离混合物的存在表明土壤可能受到了油类污染.土壤中总的正构烷烃含量有明显的时间和区域差异,总的变化范围在0.57～3.90μg.g-1.在2009年4月（枯水期）总的正构烷烃含量相对6月（调水调沙期间）要高,以黄河口湿地核心恢复区最高,其次是黄河入海前最后一个浮桥下方的黄河北岸,最后是黄河故道区域,而6月的变化趋势与此相反.这一变化趋势与总有机碳是一致的,而与中值粒径的变化趋势相反,反映了两个不同的采样时间水环境条件的差异.基于正构烷烃的分子指标,如平均链长ACL、奇偶优势度OEP、烷烃指数AI、碳优势指数CPI和陆海比TAR等表明黄河口湿地土壤的有机质的成熟度较低,有较强的陆源高等植物输入优势,且主要来自于草本植物.与其他指标相比,陆海比指标TAR更好地反映了水环境条件的变化.

英文摘要：

Surface soil samples from the Yellow River Estuary Wetlands were analyzed for total organic carbon（TOC） and n-alkanes.Molecular indicators of n-alkanes were calculated and their potential as organic matter source indicators was discussed and compared among different sampling areas and times.C25-C33 n-alkanes with odd-to-even predominance were observed in most surface soils of the wetlands,suggesting the dominant contribution of terrestrial higher plants for the soil organic matter（SOM）,and the ubiquitous presence of unresolved complex mixture indicated the presence of petroleum contamination.Total n-alkane concentrations in soils varied from 0.57 μg·g-1 to 3.90 μg·g-1,and distinct spatial and temporal differences were observed.In April 2009（dry season）,total n-alkane concentration was higher than that in June 2009（during water-sediment regulation） with the maximum concentration observed at the core area of the wetlands,followed by the north side of the Yellow River after the last pontoon bridge,and the abandoned channel area of the Yellow River.The opposite trend of total n-alkane concentration was observed in June.The variation of total n-alkane concentration at two sampling time points were positively correlated with TOC and negatively correlated with sediment grain size,suggesting the influence of hydro-environment on the accumulation of soil organic matter.Molecular indicators of n-alkanes,such as average chain length（ACL）,odd-even predominance（OEP）,alkane index（AI）,carbon preference index（CPI） and Terrigenous/Aquatic Ratio（TAR） indicated that the maturity of organic matter in soils of the wetlands was low,and the dominant source of the SOM was terrestrial higher plants and mainly herbaceous plants.Compared with other indicators,TAR is better in reflecting the variation of hydro-environment.