中国泥炭记录末次冰消期以来古气候研究进展

Advances in Palaeoclimatic Research Recorded by Peat in China since the Last Deglaciation

泥炭记录的环境演变是过去全球变化(PAGES)研究的重要领域之一,分析了中国泥炭记录的古气候演化研究的区域范围,当前主要以东北哈尼、青藏高原的红原、神农架大九湖以及华南定南大湖四个位于东部季风区的研究工作最为集中。泥炭沉积高分辨率综合信息揭示了末次冰消期以来中国气候变化的时空特征:冷暖干湿变化既有一致性又表现出区域差异,末次冰消期东北地区、东部山地、华南地区都表现出冷偏湿的气候特点,而青藏高原却为冷偏干或凉偏干;Younger Dr-yas(YD)事件之后,全新世早期和中期青藏高原、东部山地、华南地区气候总体以温湿为主要特征,而东北地区有效降水减少,到全新世晚期,呈现出干旱的变化趋势。并对B～A事件,YD事件,8.2ka以及4.2 ka等重大气候突变事件研究工作进行了综述。最后指出今后应拓展与重建更多区域古气候环境变化序列的对比,加强泥炭沉积及环境指标的基础理论,重视和提高大气沉降泥炭档案以及气候变化背景下泥炭地碳循环机制等研究工作。

Studies of palaeoclimatic and paleoenvironmental evolution recorded by peat are one of the important research areas of past global change.As for these studies since the last deglaciation in China,the works have mainly concentrated on eastern monsoon regions,especially Hani region in Northeast,Zogie-hongyuan in the Qinghai-Tibetan Plateau,Dajiuhu in Shennongjia basin and the Dahu swamp in South China,totalizing four districts.The research results on the above four areas which are characterized by high-resolution integrated information on peat deposits reveal the spatiotemporal features of climate change during the research period,i.e.there were not only consistencies of changes on temperature and humidity,but regional differences in research areas.The climate in the northeast,the eastern and southern mountain areas was displayed on a cold wet weather,whereas that in the Qinghai-Tibet Plateau was cold and dry during the last deglaciation period.However,after the Younger Dryas（YD）event,warm and wet were the main climate features in the Qinghai-Tibet plateau,the eastern and southern mountain areas during the early and middle Holocene,while in the northeastern regions the effective precipitation decreased and the climate took on a dry trend in the late Holocene.Since the last deglaciation,another remarkable feature reflected by the peat records from the eastern monsoon region has been the frequent fluctuations on temperature and precipitation,and that from Hongyuan and Hanni regions reveals there were some dry-cold events in Qinghai-Tibet plateau and the Northeast Region parallelling the north Atlantic（IRD） ice events.The results showed that the change rhythm in the long time scale（from hundreds of years to thousands of years）and climate abruption appeared again and again,which is a wider range of phenomenon and reveals the instability of climate.There had occurred several important climatic abrupt events since the last deglaciation,such as B ～ A（Blling ～ Allerd） warming period,YD event,＂8.2 ka event＂ and ＂4.2 ka event＂,the medieval warming period and the little ice age climate events.Obtaining the change intensity,process and time limit of these major events in the global major districts is crucial to further deduce the cause and incentive mechanism of the event occurrence.B ～ A event is a warm event,followed by the coldest YD event,which was recorded by the peat from Hani in Northeast,Dajiuhu in Shennognjia Basin and Dahu in South China.The most ancient peat sediments of Hongyuan region were discovered that these deposited from 13 ka BP that was close to the end time of B ～ A event.YD event had been clearly recorded by all the peat deposits of these four regions,but there were difference from its starting time and time range.The peat depositions of Dajiuhu and Hongyuan started later about 0.3 ka than that in Dahu and Hani,which might be relevant to their latitude and altitude.However,the further north the latitude was,the later the starting times of 8.2 ka event recorded by peat in China were,whereas the earliest starting time of 4.2 ka event appeared in Hani region,and the further north the latitude was,the earlier the end time came.Therefore,the two events in different regions showed that there were various time durations,which meant that they were controlled by diverse dynamic reasons or mechanisms. Finally,we prospected the future of palaeoclimatic research on the peat records,and suggested that sequence comparision among multi-regional climate change should be expanded and reconstructed.Moreover,establishing a high-resolution peat archive recording the palaeoclimatic and paleoenvironmental change for the northwest arid and semi-arid areas is significant for studying evolution mechanisms,further response processes and mechanisms of peat to climate change in the region influenced by the west wind.To strengthen the theoretical research and make an analysis of the cause,evolutionary process and its mechanism in different peatland are very important.Only by understanding the characteristics of peat deposition and development mechanism in the palaeoclimatic research recorded by peat,can the obtained environmental and climatic information be more and more reliable and persuasive.With deep understanding about the physical meaning of all climatic proxies and reconstruction of the reasonable and accurate relationship between proxies and environmental factors,the application of climate factors in the peatland is expected to make breakthroughs,which will promote the research of peatland in palaeoclimate.Improving and paying attention to the atmospheric settlement peat records,in accordance with chemical elements and the research methods of environmental magnetism,has good prospect for the atmospheric environment tracer research.In particular,using the environmental magnetism means to elucidate magnetic properties of peat sediment,mechanisms of magnetic viability and whether the change of magnetic properties is responds to the changing environment and climate should be carried on.The study of basic theory and carbon cycle mechanism of peat deposit is meaningful to research peatlands and global change.If we can carry out the peat ecological system mechanism study of the carbon cycle,to reduce the increase in greenhouse gas emissions rate and maintain ecological balance have an important meaning,what′s more,to slow current global climate change effectively has the substantial practical significance.