The humification degree of peat is a significant climatic proxy for paleoclimate change.Using the alkali-extraction method,a time series of absorbance values of the Hani peatland,Northeast China,was determined,which is used as an indicator for the humification degree of peat.Combined with14C dating data of peat cellulose,and compared withδ18O andδ13C time series of the cellulose in the Hani peatland,the evidence for the existence of14 ka paleoclimate was provided.Higher humification degrees hint a warmer-wetter climate,and vice versa.It also reconstructs the four stages of Holocene climate evolution in this region:11.5–9.8 cal ka B.P.,warm and wet period;9.8–9.0 cal ka B.P.,cold and dry period;9.0–4.8 cal ka B.P.,warm and wet period;and 4.8–0 cal ka B.P.,warm-wet and dry-cold alternation period.Meanwhile,it is revealed that the abrupt climate shifts signals such as the "8.2 ka" event and the "4.2 ka" event.Results showed that the Hani peat humification degree is of sensitive response to paleoclimate change.Therefore,it is a feasible method to analyze the relationship between paleoclimate change and peat humification degree.
泥炭作为古气候与环境信息载体,对大气汞沉降有着良好记录。文章对AMS14C定年的哈尼泥炭柱芯进行了汞含量测定,并计算其累积速率,重建了东北地区14 ka B.P.以来的大气汞沉降历史,研究了东北地区大气汞沉降对全新世气候变化和火山喷发事件的响应。结果表明,哈尼泥炭记录的东北地区大气汞沉降对包括YD事件、11.1 ka B.P.事件、10.3 ka B.P.事件、8.2 ka B.P.事件以及小冰期等气候突变寒冷事件有着良好响应,在突变寒冷事件期间大气汞含量和汞累积速率同时达到高峰值或者极高峰值。将东北地区全新世气候变化与大气汞沉降历史对比研究发现,气候干燥寒冷有利于促进东北地区大气汞沉降,反之亦然;同时,较大规模的火山喷发事件导致区域大气汞在短时间内急剧升高,泥炭沉积中大气汞沉降迅速增强。
