化石氨基酸在第四纪古生态和古气候研究中的应用 ——以吉林长白山孤山屯和江苏太湖全新世沉积物中氨基酸为例

AMINO ACID VERTICAL DISTRIBUTIONS IN QUATERNARY SEDIMENTS FROM CHANGBAISHAN BOG AND TAIHU LAKE,CHINA, AND THEIR PALEOECOLOGICAL IMPLICATIONS

近几十年来 ,随着稳定性碳同位素和14 C测年等新技术、新方法的应用 ,使第四纪研究迅速地由定性向定量发展。然而 ,氨基酸应用于第四纪古生态和古气候的研究在国内仍少有人知 ,在国际期刊上也不多见。近年来 ,作者开展了长白山孤山屯和太湖全新世沉积物的氨基酸和有机碳同位素分布与古生态、古气候意义的分析研究 ,结果表明 ,化石氨基酸同样可为第四纪的生态环境和古气候的研究提供信息 。

There is no doubt that an understanding of climatic variation during the Holocene period is necessary not only to appreciate many features of the natural environment today, but also to comprehend fully present climate. Different components of the climate system change and respond to external factors at different rates; in order to understand the role such components played in the evolution of climate, it is necessary to have records considerably longer than the time it takes for them to undergo significant changes. For this reason, scientific workers have paid much attention to the Holocene palynology and climate investigation to search global climate evolution trend in recent years. As to the Holocene palynology and climatic studies in eastern or northeast China, Chinese scientific workers have also made much progress. Most of the publications have focused on the studies of paleoclimatic variation and environment evolution investigated by using the methods of both paleoclimatic reconstruction from long Holocene pollen records and quantitative paleoclimatic reconstruction based on pollen analysis This paper mainly reports the analytical results of both amino acids and organic carbon isotope and their application in the studies of paleoecology and paleoclimate in Quaternary, and it is demonstrated that the vertical distributions of amino acids in sediments from Gushantun bog of Changbai Mountain Area and Taihu Lake have relations with the changes of paleoecology and paleoclimate. Our results indicate that the vertical distributions of total amino acids, organic carbon, organic nitrogen and organic carbon isotopic compositions (δ 13 C/δ 12 C) from Gushantun bog sediments are related to the paleoclimate and paleoecology of the Changbai Mountain Area since 13,500 yr B.P. The climate was cold in the period from ca. 13,500 to 12,500 yr B. P., with low biological productivity. The climate was assumed to be a warming period from 12,500 to 9500 yr B. P., and organic productivity and deposit rate increased apparently. The climate was warm and moist (climatic optimum period or Holocene Hypsithermal) from ca. 9500 to 4000 yr B. P. when biological productivity and deposit rate all reached higher values in the interval. From ca. 4000 yr B. P. to present, temperature was lower than the previous periods, with the biological productivity and deposit rate likely decreased. It is indicated specially that the higher values of amino acids at 1 2 m depth of the core resulted from the chemical reaction of humic acids. Amino acid, organic nitrogen and stable carbon isotope ( 13 C/ 12 C) profiles through a core from East Taihu Lake are interpreted in terms of paleoecology and paleoclimate over the last ca. 15,000 yr. Lower amino acid contents and higher δ 13 C values at the base of the core represent a cool and arid climate, and coincide with low organic productivity. A marked increase in total amino acids and organic nitrogen, with a decrease in δ 13 C values from 193 to 90 cm (ca. 6500-6000 yr B. P.), indicates a warmer and moist climate, and greater organic productivity. Amino acids then decrease in abundance, while δ 13 C values increase progressively, beginning at 73 cm (ca. 6000 yr B. P.), reflecting cooling and lower organic productivity.