青海湖地区生物中正构烷烃及其氢同位素组成与影响因素  

Hydrogen Isotope Compositions and Influencing Factors of n-Alkanes in Organisms from the Qinghai Lake Areas

作　　者：段毅 吴应忠[1,3] 吴保祥 孙涛 DUAN Yi;WU Yingzhong;WU Baoxiang;SUN Tao(Key Laboratory of Petroleum Resources,Gansu Province / Key Laboratory of Petroleum Resources Research,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou,730000;School of Earth Science ＆ Resources,Chang＇an University,Xi＇ an,710054;University of Chinese Academy of Science,Beij ing,100049;CNOOC Research Institute Ltd,Beijing,100028)

机构地区：[1]中国科学院西北生态环境资源研究院,中国科学院油气资源研究重点实验室,甘肃省油气资源研究重点实验室,兰州730000 [2]长安大学地球科学与资源学院,西安710054 [3]中国科学院大学,北京100049 [4]中海油研究总院有限责任公司,北京100028

出　　处：《地质学报》2018年第7期1541-1550,共10页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号41772108,41472121和40772069)资助成果

摘　　要：青海湖是我国最大的内陆咸水湖泊。本文应用GC-MS和GC-TC-IRMS同位素分析技术,对青海湖水生生物和周围地区陆生生物中正构烷烃及其氢同位素进行了分析,研究了生物中正构烷烃及其同位素组成。结果显示了不同生物中正构烷烃碳数分布范围在C1 5~C33之间,呈单峰型分布;主峰碳数是水生生物(除海韭菜外)相对较低,主要为C23和C25,陆生木本植物次之,为C27;陆生草本植物较高,为C27和C29;CPI值分布在4.0~29.7之间;ACL值为26.0~29.6,分布与植物类型有关。青海湖水生生物中正构烷烃氢同位素组成分布在-209.8‰^-85.6‰之间,平均值为-169.2‰^-121.2‰;陆生植物的正构烷烃δD值为-196.7‰^-84.3‰之间,平均值为-173.0‰^-108.6‰。青海湖不同水生生物和不同陆生生物之间的正构烷烃氢同位素组成差别显著。研究发现,湖泊的含盐量对水生植物的正构烷烃氢同位素具有显著影响,环境湿度和降水量明显影响了陆生植物的正构烷烃氢同位素组成;植物的正构烷烃平均氢同位素组成随着其ACL值增加,具有变轻的趋势;不同种类植物的正构烷烃合成期间具有不同的氢同位素分馏效应,与陆生植物相比较,水生植物的正构烷烃相对于环境水更富集轻氢同位素,并且随着ACL值增加,环境水和正构烷烃之间的氢同位素分馏增大。Qinghai Lake is China＇s largest inland saltwater lake.The n-alkanes and their hydrogen isotopes in aquatic plants from Qinghai Lake and terrestrial plants from the surrounding area were analyzed using GCMS and GC-TC-IRMS.The result shows that n-alkanes in different samples range from C15 to C3 3 with a single peak distribution.The main peak carbon is mainly C23 and C25 for aquatic plants,C27 for terrestrial wood plants and C27 and C29 for terrestrial herbaceous plants,showing that the main peak carbon number gradually decreases from terrestrial herbaceous plants,with the exception of T.maritimum,terrestrial woody plants to aquatic plants.CPI and ACL values range from 4.0 to 29.7 and 26.0 to 29.6,respectively,with the latter closely related to the plant species.TheδD values of n-alkanes from aquatic plants and terrestrial plants range from-209.8‰to-85.6‰（ave.δD value of-169.2‰to-121.2‰）and-196.7‰to-84.3‰（ave.δD values of-173.0‰ to-108.6‰）,respectively.There are some significant differences in hydrogen isotopic compositions of n-alkanes between different aquatic organisms and different terrestrial organisms in Qinghai Lake.The results show that the salt content of lakes has a significant effect on the hydrogen isotopes of n-alkanes in aquatic plants and the environmental humidity and precipitation significantly affect the hydrogen isotopic compositions of n-alkanes in terrestrial plants.The average hydrogen isotopic compositions of n-alkanes in the plants decrease with increasing ACL value.Different kinds of plants have different hydrogen isotopic fractionation effects during their synthesis.Compared with terrestrial plants,n-alkanes in aquatic plants are more enriched in H relative to environmental water,and with increasing ACL value,hydrogen isotope fractionation between the environmental water and n-alkanes increases.

关 键 词：青海湖 生物 正构烷烃分布 氢同位素组成 同位素分馏 

分 类 号：Q176[生物学—水生生物学]