A Preliminary Study of N-alkanes in a Sedimentary Core from Chaohu Lake

Abstract

对巢湖湖心沉积物柱样样品的正构烷烃和有机碳进行了分析.利用正构烷烃碳数分布类型、L/H、OEP指标和有机碳数据, 对该区近110年来正构烷烃的来源进行初步探讨.研究结果表明:21-25cm和16-20cm处正构烷烃以高等植物和低等生物输入并重;11-15cm即1952-1967年处具有外源性石油污染;从10cm开始, 正构烷烃以细菌、藻类为代表的低等生物输人为主;尤其是1-5cm样品正构烷烃和TOC含量明显高值, 表明该时期湖泊富营养化加剧.;The core sample was collected in Chaohu Lake in December 2001. The sediment layers were dated by ²¹⁰Pb. The results show that the sediment core represents 110 years of depositional time. Organic compounds were extracted from sediments using Soxhlet extraction by dichloromethane and methane. The n-alkanes were analyzed by chromatography/mass spectrometry. Distribution patterns of n-alkanes were presented. The sources of n-alkanes were discussed. The results show that from the depth 21 to 25cm and 16 to 20cm n-alkanes was attributed to the mixture of terrestrial plants and aquatic algae; from the depth 11 to 15cm, with sedimentary time of 1952-1967, the sample was contaminated by petroleum hydrocarbon; from the depth 10cm to surface, the source of algae and bacterium dominated n-alkanes, especially the top 5cm sample with high concentration of n-alkanes and TOC, which meant that the nutrient level especially eutrophication was increased in Caohu lake during this stage.