基于泥炭记录的过去150a东北山地大气粉尘沉降

Atmospheric dust deposition history over the past 150 a recorded by mountain peatlands in northeast China

为了探究过去150 a来大气粉尘沉降历史及其对季风边缘区和季风影响区的影响差异,利用长白山典型雨养泥炭灰分粒度、成岩化学元素、210Pb和137Cs年代等指标重建过去大气粉尘变化,并与大兴安岭摩天岭雨养泥炭粉尘记录进行比较。东北山地泥炭灰分主要以粘土颗粒和粉砂颗粒物为主。中值粒径和成岩元素特征也初步揭示东北山地泥炭中矿物灰分主要源于蒙古国和中国北方沙漠和沙地的土壤尘。大气土壤尘降通量自19世纪初至20世纪60年代表现出逐渐增加的趋势,与区域近代化、工业化和战争等人类活动强度增加一致。在过去60 a间具有减小的趋势,与区域自然尘暴的监测数据吻合较好。东北地区长距离传输的大气土壤尘降通量背景基线为(5.2±2.6) g m^(-2)a^(-1)。长白山大气土壤尘降通量(5~38 g m^(-2) a^(-1))小于大兴安岭(14~68 g m^(-2) a^(-1)),揭示了大气尘降随着与尘源区的距离增加而递减,对东北地区西部的影响要强于对东部的影响。

In order to investigate the past 150-year history of atmospheric dust deposition and its effect on the Asian monsoon zone and marginal zone, ombrotrophic peats from the Changbai Mountians were used to reconstruct the past history of atmospheric dust deposition based on the grain-size, lithogenic elements and210 Pb and137 Cs dating. The dust deposition sequences were compared with those from Motianling peat of Great Hinggan Mountains. The mountain peat ash in northeast China was mainly composed of clay and silt. The medium grain size and the lithogenic elemental fingerprints also preliminarily revealed that the mineral dust in the mountain peat of northeast China were mainly from the soil dust in Mongolian and northern China desert and sand land areas. The atmospheric soil dust deposition flux increased gradually from the 1800 s to the 1960 s, which was consistent with the increase of human activities such as regional modernization, industrialization and aggressive wars. There was a decreasing trend in the atmospheric soil dust deposition during the past 60 years in northeast China, as shown by the mountain peat records, which is in good agreement with the monitoring data of regional natural dust storms. The background baseline of the long-distance atmospheric soil dust deposition flux in northeast China is calculated as 5.2 ± 2.6 g m^(-2) a^(-1). The mean atmospheric soil dust flux was 5-38 g m^(-2) a^(-1) in the Changbai Mountain area, and that value was 14-68 g m^(-2) a^(-1) in the Great Hinggan Mountain area. The atmospheric dust deposition rates derived from the Changbai Mountain peat were smaller than those derived from the Great Hinggan Mountian peat. This suggested a decreasing atmospheric dust deposition with the increasing distance from the dust source area, and thus the influence extent of atmospheric dust deposition on the western side was higher than that on the eastern side of northeast China.