全新世哈尼泥炭地碳积累速率及影响因素

本工作研究了全新世中国东北地区哈尼泥炭地的碳积累速率与气候变化的响应机制。综合多指标腐殖化度、有机碳含量、干容重和纤维素碳氧同位素重建了哈尼地区全新世气候变化历史,并且基于定年、有机碳含量和干容重得到碳积累速率数据。哈尼泥炭时间加权平均碳积累速率28.3gC/(m2·a)。B/A暖期后期温暖湿润气候有利于碳积累,出现碳积累高峰。相对寒冷的新仙女木期碳积累速率有所降低。温暖湿润早中全新世虽有高泥炭分解,但高初级生产力还是占据主导作用,出现高碳积累速率。期间有两次火山碎屑层扰动了泥炭发育,导致碳积累速率下降。高碳积累速率一直持续到4ka BP左右大暖期结束。4.0~1.6ka BP太平洋季风减弱,泥炭表面偏干,加之降温导致低初级生产力,最终导致此阶段碳积累速率显著降低。之后季风不断增强,碳积累速率也随之增加。八次IRD降温,小冰期和新仙女木降温在哈尼都是冷湿气候组合。冷湿气候虽使有机物分解降低,但更大程度的抑制了初级生产力发展,导致低碳积累速率。

Holocene Peat Carbon Accumulation Rates and Influence Factors from the Hani Peatland, Northeast China

In this work we studied the influence of climate change on Hani peatland carbon accumulation rate. By analyzing the high-resolution records of peat humification degree, carbon content, dry bulk density and cellulose carbon and oxygen isotopes, we have reconstructed the Holocene climate changes and carbon accumulation rates of Hani peatland, Northeast China. The time weighted average carbon accumulation rate of Hani peat is 28.3 gC/(m²·a). The warm, humid climate was conducive to carbon accumulation during the late B/A warm period, so the peak of carbon accumulation occurred. The carbon accumulation rates started to drop during the cold Younger dryas. The high net primary productivity played a leading role over high peat decomposition in warmer and wetter early Middle Holocene, so the peak of carbon accumulation occurred. During this stage, two layers of volcanic debris interfere with peat development, leading to reduction of accumulation rate. The fast carbon accumulation continued to 4 ka BP, when the Holocene megatermal was over. The weak Pacific summer monsoon led to dry surface of peatland, and the drop temperature led to reduction of net primary productivity, so carbon accumulation rate declined during 4.0~1.6 ka BP. Afterwards, the Pacific summer monsoon was enhanced and the carbon accumulation rate began to increase. The climatic pattern in the Hani region is characterized by the combination of cold and wet climates in the eight IRD cold events, little Ice Age and the Younger Dryas events. The cold/wet climate combination not only reduced peat decomposition, but also significantly hampered net primary productivity, so it went against carbon accumulation.