福建仙山泥炭距今1400a以来的α-纤维素δ^(13)C记录及其气候意义

Climate Variations over the past 1400 Years Inferred from an α-cellulose δ^(13)C Record from Xianshan Peat in Southeast China

基于对福建屏南仙山泥炭沉积物中物理化学性质十分稳定的α-纤维素的提取及其碳同位素分析,重建了研究区距今1 400 a以来的气候演化历史。研究结果显示:仙山泥炭钻孔中α-纤维素δ13C值的变化范围为-26.6‰^-11.3‰,其大幅度的波动特征主要与区域降水控制的盆地沉积环境变化有关,当降水偏多时盆地积水形成类似湖泊的水下沉积环境,沉积物中有机质主要来源于δ13C值偏重的沉水植物;反之则以δ13C值偏轻的沼泽植物为主。依据AMS14C测年的结果,距今1 400 a以来研究区经历了气候偏湿(AD 600~910年)-偏干(AD910~1640年)-偏湿(AD 1640年至今)3个变化阶段。在数十年至百年时间尺度上,纤维素δ13C记录中出现的降水减少时期与太阳活动极小期(中世纪极小期、欧特极小期、沃夫极小期、史波勒极小期、蒙德极小期和道尔顿极小期)一一对应,两者呈现正相关关系,揭示太阳活动的减弱是控制研究区降水减少的主要因素,为预测区域降水变化趋势提供了依据。

We investigated the local climatic change in the central Fujian Province,eastern subtropical China,and its linkages with large-scale Asian monsoon dynamics using an α-cellulose δ^13C record of a 358 cm peat core in Xianshan Mountain of Pingnan County（118°42.7′E,26°52.4′N）.Conspicuous changes of δ^13C are observed ranging from-26.6‰ to-11.3‰ in our sedimental record,which is controlled by the local sedimental environment and the change of precipitation.During the periods with abundant precipitation,an under-water sedimental environment can be formed in the basin and organic carbon in peat core is originated from submerged plants that have positive anomalies of δ^13C.Otherwise,organic carbon is originated from C3 plants,resulting in low δ13C.Based on the AMS datings,high-resolution peat record was used to reconstruct the past climate changes over the past 1400 years,which was dry（AD 600-910）,wet（AD 910-1640） and dry（AD 1640 to present）.On multi-decadal to centennial scales in the last millennium,it is showed that each dry period corresponds to the period with minimum solar activity,which was known as Medieval Minimum（AD 640-710）,Oort Minimum（AD 1010-1050）,Wolf Minimum（AD 1280-1340）,Sprer Minimum（AD 1420-1530）,Maunder Minimum（AD 1645-1715） and Dalton Minimum（AD 1795-1820）.The good correlation between α-cellulose δ13C and solar activity indicates that the precipitation of Xianshan may be largely ascribed to the control of solar activity,which advanced the knowledge about local precipitation forecast of eastern subtropical China.