Peat Cellulose Carbon Isotopic Record And Possible Driving Mechanisms During The Past 11.5 Ka In Altay, Northern Xinjiang

The peat core (ATM10-C7 with a length of 742cm, with continuous peat deposits and plant residues enrichment between 0 to 723cm), had been sampled from Altay Mountains in north Xinjiang, with sampling site at an elevation of 2450m which belongs to the typical mountain peatland. Here we finally establish a set of extraction process which is effective for peat core samples of a-cellulose, with a large amount of experiments referencing the extraction process of a-cellulose in treering, lakes, and peat at home and abroad. Based on above method, we extract a-cellulose and then perform the stable carbon isotope measurement and analysis, to establish the evolution sequence of paleoenvironment conditions since 11,500 yr B.P. In order to verify the interpretation of stable isotope of peat cellulose. Monthly precipitation, sedge, peatland water, streams water were collected from peatland of Altay Mountains during April to September in 2 014, with collecting sedge samples from areas across 2000-2450 m elevation and other 23 modern plants samplesfrom peatlandinJuly,12 tree cores extracted from 4 Siberian larch trees at an altitude of 2000 m in August as well. Cellulose was extracted from those collected sedge, modern plants sample and tree cores, then stable carbon isotope was conducted in special instruments.The result of modern process in Altay, demonstrate that the correlation between carbon isotope of a-cellulose in Sedge, dominant plant, is insignificant both in temporal and spatial, and there are the same obvious positive correlations between average temperature in June-August and the carbon isotope of a-cellulose in treering which is sampled near the peatland. With analyzing the results of modern peat plant investigation around the world, simutaneously compared with the stable carbon isotope records in domestic typical peat and the others moisture records from arid central Asia, Further comparison with other reliable temperature records, including δ180 records of ice core in Tibet Plateau and the marine deposit records in the North Atlantic, we preliminarily conclude that the δ13C record of Altay peat cellulose is primarily a paleotemperature indicator. So the carbon isotope of a-cellulose from Altay peat mainly reflects variability of paleotemperature since 11.5 ka BP, and show "V" type of relatively high temperature in the early and late Holocene but relatively low temperature in mid-Holocene. There are four stages in the paleotemperature evolution sequence:11.4～9.9 ka BP is the low temperature stage; 9.9～6.2 ka BP is the high temperature stage, but with some obvious fluctuations in cold events; 6.2-3.9 ka BP is the relatively low temperature stage; 3.9-0 ka BP is the relatively high temperature stage.Further analysis of forcing mechanism indicate:at the orbital scale, temperature change from the δ13C record is mainly controlled by insolation and the content of greenhouse gases, specific performance show that:high temperature stage is mainly driven by solar radiation during the earthly Holocene, warming trend in Mid-Holocene may be associated with an increased content of greenhouse gases in the atmosphere. On millennial scale, it is clearly that there is a close link betweenclimate abrupt events in the δ13C record of Altay peat cellulose and ice-rafted debris (IRD) events in the North Atlantic, implying that the temperature change of the North Atlantic has a certain influence on the temperature of aridcentral Asia (ACA) through Westerly cycle. Both power spectrum and the abrupt events comparative analysis imply thatthe paleotemperature evolution history extended 11.5ka in the study region maybe also superimpose impacts of the North Atlantic and solar activity.Owing to the indetermination of environmental interpretation of δ13C and δ18O in peat cellulose, it is significant that modern process of relevant research must be carried out to verify the interpretation of stable isotope of peat cellulose in a certain location. Our preliminary results show that Altay peat cellulose δ13C have great potential for reconstructing Holocene temperature. It is also of great significance that paleoclimate reconstruction research on paleotemperature with high resolution is carried out, aiming to understand the pattern of climate change in ACA during Holocene and explore the possible driving mechanisms.