摘要:
利用气相色谱—质谱联用仪(GC—MS)对星云湖76 cm长的沉积岩芯类脂物分子中脂肪醇进行分析,揭示了近130 a以来星云湖地区环境演变过程。结果表明：脂肪醇碳数分布C12～C30呈有规律变化:76~60 cm深度表现为高碳数与低碳数相对平衡态势,60～38 cm逐步变为以高碳数为优势, 38~12 cm高碳数较前阶段降低,12~0 cm低碳数显现明显优势。低碳数与高碳数组分的比值Rl/h介于0.13~4.1之间,在人类活动干扰较小状况下,Rl/h变化与气候的冷暖变化具有显著的对应关系,明显揭示出了相对寒冷(1920年前)—温暖(20世纪30—50年代)—较寒冷(20世纪60—70年代)温暖(20世纪80年代)的气候变化阶段;20世纪90年代以后,湖泊富营养化快速发展,Rl/h也随之急剧增加。反映出脂肪醇对湖泊环境变化记录的灵敏性以及人类活动的干扰可能对环境自然演化的痕迹予以改变,产生叠加放大或抵消效应,使得现象解释更加复杂。从多种代用指标交合中提炼判识自然与人为因素对环境的影响,是现代沉积物研究中必须注意的问题。
Abstract:
A 76 cm core was drilled from Xingyun Lake, in the center of Yunnan Province, southwest China, to get the environment change record. Using GCMS analysis, a series of lipids, including nalkanes, nalkanoic acids and nalcohols, have been identified. This paper focuses on nalcohols in this core. Result shows that the distinct nalcohols distributions in different depth. The chromatographic peak of most of the samples are identified according to carbon number (arrangement) in double peak, in which the former and back main peak carbons are C16 and nC26, respectively; the evenodd carbon predominance both in the lower and higher carbon number nalcohols. The carbon number components of lower and higher are in the relative balance at 76~ 60 cm, dominated by higher at 60~38 cm, the higher present in less abundance at 38~12 cm and the lower show greater abundance at 12~0 c m depth. The rate of the higher carbonate components to the lower (Rl/h ) are between 0.13~4.1 , which have marked corresponding relation to the temperature curve under the less human effect. Four climate stages can be divided according to the records since about 130 a, i.e. cool period before 1920 ,warm period between 1920~1956 with the warmest period in 1940s′, cold period between 1957~1970s and warm period 1980s. Since 1993 Rl/h increase may record the euotrophic history of the lake. The carbon preference index (CPI) reveals the organic origin of the lake has some alternations. More attention must be paid to that the high effected by the euotrophic which may lead the the high Rl/h.The lipids are sensitive to the environment evolution. However, further and more detailed work should be done for better understanding the relationship between environment evolution and Lipid records.
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