长白山区全新世大暖期的氨基酸和碳同位素记录

THE RECORDS OF AMINO ACIDS AND ORGANIC CARBON ISOTOPE FOR HOLOCENE MEGATHERMAL IN CHANGBAISHAN AREA

根据长白山孤山屯沼泽沉积物的氨基酸、有机碳、有机氮和有机碳同位素 (1 3 C/ 1 2 C)垂直分布的研究 ,揭示了长白山区距今 13.5 ka以来的气候环境特征及其演变过程 :大约距今 13.5 - 12 .5 ka,气候严寒 ,不利于生物的繁衍 ,生物产量处于较低值 ;距今 12 .5 - 9.5 ka,气温处于上升期 ,但年均温度仍低于现今温度 ;距今 9.5 - 4.0 ka,可判定为全新世大暖期 (Megatherm al) ,气候温暖潮湿 ,有利于生物的繁衍 ,生物产量较高。其中大约距今 8.6 - 7.5 ka期间 ,氨基酸、有机碳、有机氮分布均出现较高峰值 ,而有机碳同位素 (δ1 3 C)则出现较低峰值 ,可以推测这一时段为全新世大暖期的鼎盛期 (Megathermal Maximum) ,生物极为繁盛 ,生物产量处于最高值 ;距今 4.0 ka以来 ,气温有下降趋势 ,生物产量有所减少 。

This paper reports the study on the paleoclimate and paleoecology of the Changbaishan area based on the vertical distributions of amino acid, organic carbon isotopes, organic nitrogen, and total organic carbon in the Gushantun bog over the last 13 500 years. Analyses of amino acid, organic carbon, organic nitrogen and organic carbon isotope( 13C/ 12C) for a 9.5-m-long sediment core (Gu3), and palynological analysis for a 9.5-m-long sediment core (Gu2), taken from the Gushantun bog on the northern slope of the Changbaishan, northeast China, provide detailed information regarding the history of climate and ecological environmental changes over the last ca.13 500 yr. In general, lower amino acid contents and higher δ 13C values at the base of the core represent a cold climate, and coincides with low organic productivity. A marked increase in total amino acids, organic carbon and organic nitrogen, with a distinct decrease in δ 13C values from 9.0-7.5m (12 500- 9 500 yr B.P.), reflect the temperature rise in the interval. From 7.5 to 3.0m (9 500-4 000 yr B.P.), higher contents of amino acids, organic carbon and organic nitrogen, and lower δ 13C values, show that the climate was warm and moist (or called as Holocene Megathermal), coinciding with the higher organic productivity. Amino acids and organic nitrogen then increase in abundance, while δ 13C and organic carbon values progressively decrease, from 3.0m and upwards, reflecting that the bog condition started around 4 000 yr B.P. The pollen results are largely identical with the above views. Our analytical results indicate that the vertical distributions in total amino acids, organic carbon, organic nitrogen and organic carbon isotopic compositions ( 13C/ 12C)from Gushantun bog sediments can be related to the paleoclimate and paleoecology of the Changbaishan area since 13 500 yr B.P. The climate was a cold period from ca. 13 500 to 12 500 yr B.P., with low biological produc- tivity. The climate was as a warming period from 12 500 to 9 500 yr B.P., and organic productivity and deposit rate increased significantly. The climate was warm and moist (or climatic optimum period, and called as Holocene Megathermal) from ca. 9 500 to 4 000 yr B.P., when biological productivity and deposit rate all reached higher values. From ca. 4 000 yr B.P. to present, temperature was lower than previous period, with the biological productivity and deposit rate decreased. It is explained that the abundance of amino acids in the interval resulted from the effect of humic acids, and the lower δ 13C value did in the heterotrophic sources.