福建仙山泥炭腐殖化度记录的1500年来气候变化

The past 1500 years climate change recorded in peat humification at Xianshan in Northern of Fujian Province

以福建北部屏南仙山泥炭剖面岩性、孢粉记录、C/N值作为参考,讨论了仙山泥炭剖面腐殖化度的气候环境意义。依据AMS^(14)C测年数据构建年代序列,以腐殖化度为主要代用指标,将最近1500 a来的气候变化划分为3个主要阶段——Ⅰ:AD 527—850,相当于隋唐温暖期,泥炭腐殖化度较高,指示气候温暖湿润;Ⅱ:AD 850—1750,腐殖化度总体较低,反映总体上较寒冷干燥的气候,其中中世纪暖期(MWP)信号较弱,而小冰期(LIA)寒冷气候表现明显。Ⅲ:约AD 1750至今,腐殖化度为剖面最大值,且波动较大,显示为温暖湿润环境。利用re dfit方法对泥炭剖面腐殖化度和C/N时间序列进行谱分析发现,存在173 a、41 a、32 a、22 a的显著周期,反映了中低纬度亚热带季风区气候变化对太阳活动的响应。

Humifieation is a proxy describing the degree of decomposition of plant remains. Since the process of plant decomposition involves both the local climate and other conditions, humification can be used to indicate variations of sedimentary environment or palaeoclimate. We do a research with the peat humifieation of Xianshan section on the subtropical monsoon region Pingnan, east China. With reference of pollen and C/N vaule,we discuss the climate environment significance of peat humifieation. Besides, the chronological sequence of this core was established using 4 AMS 14^C dates, and according to the comprehensive analysis of the peat humification, combined with pollen records, TOC, TN, C/N for the profile, we reconstruct nearly 1500 years climate history of the study area, which can be divided three phases. I： AD 527-850, equivalent to the warm stage of Sui and Tang dynasties, peat humification is higher, indicating a warm and wet climate; II： AD 850-1750, overall,the peat humification is lower, indicating a relatively dry and cold conditions, of which AD 800-1200, corresponding to the MWP, the signal of the peat recorde is not significant, however, the LIA has a significant performance;III： about from AD 1750 to the present, the peat humification is the highest of whole section, generally, has a increasing trend, indicating precipitation increased, which as warm and wet environment. In addition, using red noise spectrum analysis with the redfit 3.8 show that there exist aquasi-periodic with 1127 a, 173 a,41 a,32 a,22 a,21 a,18 a in changes of humifieation and C/N, which are in relation to climate of the monsoon region at low-latitude subtropical change on the secular solar activity response.