正构烷烃：解锁古气候密码的关键钥匙

N-Alkanes: The Key to Unlocking the Ancient Climate Code

摘要: 本文围绕正构烷烃在古气候研究中的关键作用展开。古气候研究对地球演变、气候预测及生态社会发展意义重大，正构烷烃因独特性质与广泛分布在其中占据关键地位。其化学结构稳定，碳链长度、丰度和同位素组成等特征与古气候要素密切相关。来源涵盖陆生植物、水生生物及地质作用，不同来源正构烷烃为古气候研究提供多元信息。通过碳、氢同位素分馏机制，与光合作用、生物代谢、水体蒸发等环节相连，反映古气候的温度、降水、大气CO₂浓度等要素变化。在湖泊、海洋、泥炭沼泽等地质载体中，正构烷烃记录了区域气候的干湿冷暖、生态演替及人类活动影响，如呼伦贝尔沙地伊和沙日乌苏湖、中国西南杞麓湖等案例所示。常用指标包括碳优势指数、平均碳链长度和正构烷烃比值指标等，多指标综合运用可弥补单一指标局限，提升古气候重建准确性。在研究方法上，样品采集需兼顾时空代表性，预处理要去除杂质、富集目标物；仪器分析技术有气相色谱、气相色谱–质谱联用和稳定同位素分析技术等，各有优势。当前研究面临正构烷烃来源复杂、指标不确定、样品保存与污染等挑战，但未来技术创新如高精度分析和原位监测技术发展、多学科交叉融合，以及跨区域对比与综合研究趋势，将推动正构烷烃古气候研究深入，助力揭示地球气候变迁奥秘与应对气候变化。

Abstract: This paper focuses on the crucial role of N-alkanes in paleoclimate research. Paleoclimate research is of great significance for understanding Earth’s evolution, predicting climate change, and promoting ecological and social development. N-alkanes play a key position in this field due to their unique properties and wide distribution. Their chemical structures are stable, and characteristics such as carbon chain length, abundance, and isotope composition are closely related to paleoclimate elements. The sources of n-alkanes include terrestrial plants, aquatic organisms, and geological processes, and different sources provide diverse information for paleoclimate research. Through carbon and hydrogen isotope fractionation mechanisms, which are linked to photosynthesis, biological metabolism, water evaporation, and other processes, they can reflect changes in paleoclimate elements such as temperature, precipitation, and atmospheric CO₂ concentration. In geological carriers such as lake sediments, marine sediments, and peat bogs, N-alkanes record the dry-wet and cold-warm changes of regional climate, ecological succession, and the impact of human activities, as demonstrated by cases such as Lake Yihesariwusu in the Hulun Buir Sandy Land and Lake Qilu in southwest China. Commonly used indicators include the carbon preference index, average chain length, and n-alkane ratio index. The comprehensive application of multiple indicators can overcome the limitations of a single indicator and improve the accuracy of paleoclimate reconstruction. In research methods, sample collection should consider both spatial and temporal representativeness, and sample pretreatment aims to remove impurities and enrich target compounds. Instrumental analysis techniques include gas chromatography, gas chromatography - mass spectrometry, and stable isotope analysis technology, each with its own advantages. Current research faces challenges such as the complexity of N-alkanes sources, uncertainty of indicators, and sample preservation and contamination problems. However, future technological innovations, such as the development of high-precision analysis and in situ monitoring technologies, multidisciplinary integration, and the trend of cross-regional comparison and comprehensive research, will promote the in-depth study of N-alkanes in paleoclimate research and help to reveal the mysteries of Earth’s climate change and address climate change.