若尔盖高原花湖泥炭沉积及其对气候变化的响应

摘要

Natural radionuclide 210Pb,soil water content,and dry bulk density data were used to calculate the geochronology and characterize the recent peat sedimentation rate of a soil profile obtained near Huahu lake on Zoige plateau.We analyzed the change characteristics of total organic carbon (TOC) content with depth and age,and calculated the recent rate of carbon accumulation (RERCA) of this peat section.It was concluded that the average peat sedimentation rate was 0.16 cm·a-1 between 1824 and 2011,which is close to the reported values in other studies on Zoige peatlands.The weighted average sedimentation flux during this time span was 0.082 g· cm-2·a-1 and the RERCA was 86.12 g·m-2 ·a-1,which are comparable with the reported values in other researches.The differences indicate the specificity of the peatland formation and development.Using the climate data collected by the weather station,the data of mean annual temperature (MAAT) reconstructed by climate proxies in other researches,and the satellite observated climate data,we found that the main impact factor on climate change on Huahu peatland in recent decades was precipitation,which means that high annual precipitation in that region may contribute to the high carbon accumulation rate.Anthropogenic activities and other factors also constitute an interference in peat and carbon accumulation rate,which needs further study.%青藏高原东北缘若尔盖高原泥炭地一直是第四纪气候变化和地质活动的研究热点.通过210Pb放射性测年技术的恒定补给速率模式建立若尔盖高原花湖泥炭地30 cm泥炭剖面的高精度年代框架(1824-2011年),得出该年代序列下泥炭剖面的厚度沉积速率为0.16cm·a-1,加权平均沉积通量为0.082 g·cm-2·a-1.通过泥炭的干容重和有机碳含量,计算出泥炭剖面的有机碳沉积速率,即近现代碳积累速率为86.12 g·m-2·a-1.结合气象台站观测数据、卫星观测模拟数据以及气候代用指标重建的气候数据,探讨年平均气温和年平均降水对该泥炭地碳积累速率的影响,得出花湖泥炭地对近现代气候变化的响应主导因子为降水.为进一步研究若尔盖高原泥炭地的泥炭发育和碳积累情况提供参考依据.