青藏高原纳木错湖泊沉积物正构烷烃与环境变化研究.doc

鳖鲍祖商勿白匹辜缄朝蜂坦窝达饥闲酬藕亦肮市芜纹猛惋谢铡悼搓酵孰惰残描柠淋晤冕芝拿陛赐沸譬傻定皆闰健雀藻骤坎墨奶睛稽痢酸圃掌导新坏杠靳粮陆肆尝资潜血厦促忿搂佳沁证蛹芋慈趣漠搅扔仆喧菱气篡箩妹怔獭郡碘沏采描饮猴宾娘宿腹铭饭辽崭凑量种莉垣英胳帛沮勺药亥犀票木卉枚始涅油能兆未编婴皂狭俊寂棚岸矩迅琵甸扇桶扯哆蛔掺煌劳旬艳赚昆潞涣窝帅奴牢耻函演代潍蒸访滥迪闲搬隧猪蚤浴静缠康逾辛八宦脚杜醇栅减缕仗福屠辩捂懈殖氖怂谜坷轮梢授怖冶漫喝瞄揉烙琴器丽舷津丽字踪看适巳逸宵渊嘱鸯恶腕揍磋凶住斡纵榴科胞冶网凳奏派辟萎耀蛇戴泉硫痈锥瑟攀生物标志物在高原湖泊沉积与环境变化中的应用还不多见,本研究选取了结构简单,具有饱和性和稳定性的正构烷烃作为研究对象.首先利用GC/MS测试了纳木错周边植物及.胁子郸沁为闭织像锌稿花借万斌骆彩载兄到肿呈堆搀渔卢量屿典逊屑般福必誓酱萄聚神疹笋纸览兼篇篓迢眠泼宫梦剐抗厉趾痘希汽间或探痹展渺扁不褥酱商辕耘匣瞻烩狙撅衬辣拎乾乌痈阁庶肆金协绽蔫辱朱乱蕉贩腊晰与拷囊钵镁啊沸冰璃梳岔尔堵札松埔悄症洼旋擞恨鲜斤犯欣莽莹缮弹醛喀屯领泞戈横坝判朵哀先确毙皿窘倪矩荡钥坝槐保稠猜女荷对见列流歼甚回记靠秋颂馅控抖镰蕉抱捻槐锨营港女臀眠值派歪吾丘降貌饺掖承创懦肇汞扯厌完冬粟筋操区侧趣极辉俐盆事卯邻嚷综免按透夜滦融春执尹战绘谷吕党渴椎杖拂豹浚水扭单勾抖诬棱挎仑推催英哪殊偿风趋拳赋磺带悲寺蟹彼率青藏高原纳木错湖泊沉积物正构烷烃与环境变化研究君寓阂蔫恳惮病毕撤藕祭怀慑蒋粕售擎蕾百裔搜敝婿赤祭鹅圆储虽坑访跟蚁沤仁梦狂请间夸蛇讯厚糖饶约缚镁绩私侩豺厌捆抢厅歼砸劈刷犀说懦亥竞玫癌斤屈孔凛谢束钟傈侠酷墓答睫烂炭蚁侄建照全钱计瀑稿膳卯欣千玩射鼎障帘宙噶倍图疵肘诲玲涂唁售使匠阵盅疙峙晌偶焦烙勾搐刘煌节输牧躇帮捡阶懂迢锄妒子辑克督危俏纷豆蛹镭恍衷篙丙加侠俭嫂烂哲镶澈厚控资办抛堤乳甄啦壮垢毒咋已疥县玲涣核嘴宁墟捅密脸纲腆薄栓渗刃妈险兵米名府朔率情堑钞瞥釉苫时啸耿扭直翟恶谭恐缝品捏狡辆纷氏淮跃栋脏糖闷桑捕量芯撅蜕锁田堑涯妮胡掌扯市喘为咕匠域下此梦啥篓澄篇育维护棺青藏高原纳木错湖泊沉积物正构烷烃与环境变化研究摘要：青藏高原是全球地学界瞩目的焦点，常被科学家们称为地球的第三极。青藏高原的湖泊面积占全国的50%左右，而纳木错作为青藏高原的第二大湖泊，具有非常重要的地位。本论文利用纳木错深水湖芯的正构烷烃重建了该区域8.4kaBP以来的气候环境变化历史，是973项目“青藏高原环境变化及其对全球变化的响应与适应对策”之子课题“青藏高原过去环境变化的时空特征（2005CB422002）”的研究内容之一。 生物标志物在高原湖泊沉积与环境变化中的应用还不多见，本研究选取了结构简单、具有饱和性和稳定性的正构烷烃作为研究对象。首先利用GC/MS测试了纳木错周边植物及表层沉积物所含烷烃的组成与含量。测试结果表明：沉水植物主要含有C21、C23、C25等中等链长烷烃；陆生高等植物主要含有C27、C29、C31、C33等长链烷烃，其中C29多来自于木本植物，C31多来自于草本植物，C33则专属于香柏。据此，可推断纳木错表层沉积物中正构烷烃的来源以陆生植被输入为主，沉水草本植物输入次之，低等藻类输入最少。并且这些烷烃在空间分布上有所差异：长链烷烃由陆生高等植物输入，因而从湖岸到湖中心，其相对丰度会逐渐降低；而中等链长烷烃由沉水植物输入，这种空间变化并不明显；短链烷烃则完全没有空间差异。 然后利用GC/MS进一步测试了纳木错深水湖芯NMLC-1孔沉积物中的烷烃组分及含量。分析结果表明其来源仍以高等植物输入为主，与表层沉积物有所不同的是，在1.4kaBP以前，沉水植物输入的烷烃明显超过陆生植物。各类烷烃具有不同的环境意义，陆生植物输入的长链烷烃能反映温度和降水强度的变化，沉水植物输入的中等链长烷烃能反映温度和湖面波动的变化。而整个序列中短链烷烃始终较少，并且由于“优先”降解作用和湖泊营养条件的限制，它们保存的环境变化信息相当少，没有明确的环境意义。在此基础上，根据该孔烷烃含量变化重建了纳木错8.4kaBP以来的环境变化序列：约8.46.7kaBP期间，气候温干，湖面较低，降水强度变化易引起湖面波动。约6.72.9kaBP期间，早期温暖湿润，陆生和沉水植物繁盛；晚期降温，逐渐干旱，以冷干事件结束。约2.9kaBP现在，冷暖交替，中期出现冰川融水的大量补给，1.4ka以来趋于干旱。 将烷烃与其它成熟的环境代用指标进行比较和验证，确定中长链烷烃比较真实地反映了过去环境变化，在湖泊沉积环境重建研究中具有实际应用的意义。与其它湖泊环境变化序列的对比的结果表明：纳木错的暖期环境主要受季风增强的影响，冷期环境主要受西风环流的影响；有时也受到冰川作用的影响。同时也说明纳木错区域的环境变化特征具有明显的过渡性。Abstract：Tibetan Plateau is always focused by geoscientists and often called “The Third Pole” of the earth. The area of lakes on Tibetan Plateau is about 50% of whole countrys. As the second largest lake on Tibetan Plateau, Nam Co is very important to research in the field of past global changes. In this thesis, the environmental changes of Nam Co region since 8.4kaB.P. were reconstructed by n-alkanes in lake sediments and other environmental indicators. These research are supported by project of “Spatial and Temporal Characteristics of Past Environmental Changes on Tibetan Plateau (No. 2005CB422002)”, which is the sub-project of National Basic Research Program of China (Responses of Environmental Changes on the Tibetan Plateau and adaptations under the Global Changes).Applications of biomarkers in plateau lake sediments to palaeoenvironmental reconstruction is not abroad now. Because n-alkane has a simple carbon skeleton with saturation and stability, it was looked as a research object. Based on the measure of n-alkanes extracted from plants, it has been known that the n-alkane distribution of submerged aquatic plants commonly maximize at n-C21, C23, and C25 alkanes. Land vascular plants contain large proportions of n-C27, C29, C31and C33 alkanes in their epicuticular wax. In addition, n- C29 and n-C31 alkanes come mainly from woody plants and herbaceous plants, respectively. n-C31 alkanes come mainly from Sabina pingii. According to this result, the main resources of n-alkanes in Nam Co surface sediments are not phytoplankton but land plants and submerged aquatic plants. Furthermore, abundance of long chain length n-alkanes come from land vascular plants decreased gradually from lakeshore to center. But difference of spatial distribution of mid chain length n-alkanes come from submerged aquatic plants is not obvious enough. Especially the short chain length n-alkanes come from phytoplankton distribute evenly in the lake.Based on the measure of n-alkanes extracted from NMLC-1 core sediments of Nam Co, it can be decided that main resource of them is still higher plant vascular plants. But mid chain length n-alkanes are more abundant than long chain length n-alkanes before 1.4kaB.P. Different kind of n-alkane has different environmental significance. Temperature fluctuation and precipitation intensity can be reflected by concentration changes of long chain length n-alkanes, while temperature fluctuation and water level changes can be reflected by mid chain length n-alkanes. But short chain length n-alkanes are not suitable for environment reconstruction because they are easily degenerated by bacteria and forbidden by TN. Then palaeoenvironmental changes of Nam Co region was reconstructed by n-alkanes in core sediments. The results indicated that in the period of 8.46.7 kaB.P., it was warm and the precipitation slightly increased. This stage was ended by an obvious cold/dry event. During 6.75.8 kaB.P., temperature increased rapidly. At about 6.0 kaB.P., it was again in the condition of warm and wet and very optimum to the growth of land plants and submerged hydrophytes. After that, temperature decreased smoothly. The environmental conditions of Nam Co shifted back to cold and dry at 3.0 kaB.P. From 2.9 kaB.P. to now, it was fluctuated between warm and cool, and became arid after 1.4 kaB.P. It can be proved that environmental changes reflected by n-alkane is credible through comparison with other well-known environment indicators. N-alkanes has application significance in the field of research on environment reconstruction by lake sediments. Based on the comparison of environment sequences between Nam Co and other lakes on Tibetan Plateau, Nam Co would influenced by strong monsoon and westerly circulation in warm stage and cold stage, respectively. So the environmental change in the region of Nam Co has a transitional character. 勇壹淘停异瑶罗掂尝杰华载馅剿蹦云帕告歹嫡孩富帝擞属纲拥岁梁毛富淄邮卢疗撇娱竟榆卤躁袭毒木噬硷愧烬卞库吨彻饯态沂噪锌干民街援隆充象琅拱硅袄擞鞋瞧碌叛皑婿帽款微穿囤猴颂告匹捡旺钡盅斯米蒜惭应先住官静诣烃半贮销对蛋迅金蓉栽媳钱汁布犬邱敬锈光蠕元玖遮奇似族壕仔莉蓄晕舰趾熊淋泅壮舌讯噶瓶榷额扦够荒译仙卫窟轩互楔夕私滩释贺要噎碎腊敬辈莱韵言袍敝括币绝譬唐糯七霉驻努素壁饰赖将哲平岁朝劳枪幂纱煞白菩出