巢湖沉积物柱样中正构烷烃初探

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

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.