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| 云南星云湖沉积物正构烷烃记录的近代环境变化 | |
| 引用本文： | 张宏亮,李世杰,冯庆来,张世涛.云南星云湖沉积物正构烷烃记录的近代环境变化[J].第四纪研究,2008,28(4):746-753. |
| 作者姓名： | 张宏亮 李世杰 冯庆来 张世涛 |
| 作者单位： | 1. 中国科学院南京地理与湖泊研究所湖泊与环境国家重点实验室,南京210008;中国科学院研究生院,北京100049 2. 中国科学院南京地理与湖泊研究所湖泊与环境国家重点实验室,南京,210008 3. 中国地质大学地球科学学院,武汉,430074 4. 昆明理工大学,昆明,650093 |
| 基金项目： | 国家自然科学基金重点项目 , 国家科技部重大基础研究前期研究专项项目 |
| 摘 要： | 为探讨气候变化与人类活动对湖泊环境影响在湖泊沉积中的记录,在云南星云湖水深8.2m处采集1支85cm长的柱状沉积岩芯,利用气相色谱-质谱联用仪（GC-MS）对沉积岩芯中的类脂物分子进行分析,揭示了近160年以来星云湖地区环境演变过程。分析结果表明沉积岩芯中的正构烷烃碳数分布C15～C35呈有规律变化:85～60cm深度表现为低碳数相对优势,60～32cm逐步变为以高碳数为优势,32～10cm高碳数较前阶段降低,10～0cm深度低碳数显现明显优势。同时,平均碳链长度（ACL）、高碳数同系物与低碳数同系物比值（H/L）以及C27/C31等结果还揭示出:近160年来湖泊沉积中有机物输入经历了内源低碳（1920s前）、外源高碳（1920s～1980s初）和内源低碳（1980s初～2004年）为优势的演变过程;在人类活动干扰较小状况下,H/L变化与气候的冷暖变化具有显著的对应关系,即H/L低值段明显对应于气候的相对寒冷期,H/L高值段明显对应于气候的温暖期。在1990年代以后,尽管气候持续变暖,但由于人类活动影响加剧,湖泊富营养化快速发展,H/L值却随之急剧降低,反映出沉积岩芯中的类脂物可敏感记录人类活动对湖泊环境变化的影响。 |
| 关 键 词： | 星云湖 湖泊沉积 类脂物分子 正构烷烃 近代环境变化 |
| 收稿时间： | 2008-04-30 |
| 修稿时间： | 2008-05-16 |
ENVIRONMENTAL EVOLUTION RECORDED IN BIOMAKERS FROM LACUSTRINE DEPOSITS OF THE XINGYUN LAKE |
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| Zhang Hongliang,Li Shijie,Feng Qinglai,Zhang Shitao.ENVIRONMENTAL EVOLUTION RECORDED IN BIOMAKERS FROM LACUSTRINE DEPOSITS OF THE XINGYUN LAKE[J].Quaternary Sciences,2008,28(4):746-753. | |
| Authors: | Zhang Hongliang Li Shijie Feng Qinglai Zhang Shitao |
| Institution: | 1. State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology Chinese Academy of Sciences, Nanjing 210008; 2. Graduate University of Chinese Academy of Sciences, Beijing 100049; 3. Faculty of Earth Science, China University of Geosciences, Wuhan 430074; 4. Kunming University of Science and Technology, Kunming 650093 |
| Abstract: | A 85cm core marked as XY-1 was obtained from Xingyun Lake in central Yunnan Province,Southwest China,to assess environmental changes and to examine the relationship between human activities and natural factors.Using a GC/MS analysis,a series of lipids,including n-alkanes,n-alkanoic acids,n-alcohols,and n-alkan-2-ones have been identified.This paper focuses on n-alkanes from this core.Our result shows that the n-alkanes with carbon numbers ranging from C15 and C35 exhibit systematic distribution patterns in different layers.The chromatographic peaks of most of the samples are identified according to carbon number(arrangement)in double peak,in which the dominating compounds are C17 and C29,respectively;the odd-even carbon predominance both in the lower and higher carbon number n-alkanes.The compounds with lower carbon numbers are present in greater abundance at the core intervals of 85-60cm and 10-0cm,dominated by higher carbonate components at 60-32cm and in the relative balance at 32-10cm.The CPI(carbon preference index)of the n-alkanes ranges from 0.55 to 3.35,while CPIh and CPIl are between 1.3-6.3 and 0.3-1.6,respectively.The ACL(average chain length)ranges from 19.2 to 25.7 and is a little lower than that of general lake sediments.The ratios of the C27/C31 are between 0.43 to 1.63,reflecting the relative vegetation type of tree and grass.The rate of the higher carbonate components to the lower H/L are between 0.16-3.18,corresponding to the temperature curve under a less human effect.High H/L value indicates a warm climate.Four climate stages can be recognized according to the records since about 160a,i.e.cool period before 1920s,warm period between 1920s to mid-1950s with the warmest period in 1940s,cool period between mid-1950s to 1970s,and warm period 1980s.Since early 1990s sediment H/L decrease may indicate the beginning of an eutrophic history of the lake.The ACL,C27/C31,and H/L reveal the change of origins for organic matters of the lake sediments with the alternation of predominance of the inner low carbonate(before 1920s),outer high carbonate(early 1920s-early 1980s),and inner low-carbonate(1980s-2004).This record also marks some human activities which resulted profound environmental changes,such as the dredging Gehe channel in 1923,denudation and excessive reclamation during the end of 1950s,and especially the eutrophication of the lake since about early 1990s.The lipids are sensitive to the environmental evolution;however,the increasing human activities may affect the record of the natural changes.Further work should be focused on a better understanding of the relationship between environmental evolution and lipids records with a consideration of the human activities as the background. |
| Keywords: | lacustrine deposits biomakers n-alkanes Xingyun Lake |
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