长白山区泥炭沼泽磁化率特征及其环境意义

Characteristic and Environmental Significance of Magnetic Susceptibility of Peat Bog Sediments in Changbai Mountains

以长白山区泥炭沼泽为研究对象,沿不同海拔选择赤池、锦北、大牛沟、金川和哈尔巴岭5个代表性采样点。通过对沼泽垂直剖面的精细采样,利用210Pb和137Cs方法对5个剖面进行高精度定年,综合研究和分析泥炭沉积物质量磁化率沿深度垂直分布特征,进而揭示其环境意义。结果表明,长白山区泥炭沼泽磁化率在表层具有明显的富集规律,富集时间始于20世纪初,并在20世纪后期达到峰值,且其富集含量可达以下层位富集平均值的5～10倍;长白山区泥炭磁化率的表聚性特征反映了在盛行西风等自然因素作用下,大气降尘和城市扩张等多种人类活动对区域环境的影响,很好地指示了区域磁性颗粒物污染扩大和加剧趋势。

Peat is the result of the in - situ accumulation of organic matter in waterlogged conditions where dead plants decay slowly because of lack of oxygen, which ensures peat bog to contain an unparalleled record of our past as one type of environmental archive. Great numbers of peat bogs are important and accessible to us in Changbai Mountains as one of the main evolving areas of peat. As the important characteristic of sediments, including peat, magnetic susceptibility is one considerable useful index to be used to document the histories of environmental changes and the influences of the human being＇s activities because not only the method of measurement of the magnetic susceptibility is simple, fast and economical, but also this parameter is sensitive to human activities＇ interferences on nature. In this paper, Chichi, Jinbei, Daniugou, Jinehuan and Haerbaling peat pro- files were chosen along the altitude as sampling sites, and the temporal distributions and implications of the mag- netic susceptibility of peat sediments were discussed synthetically through the 5 vertical sections in high resolving powers in Changbai Mountains. The depth -age models of 5 peat cores are built according to 210pb and 137Cs dating methods. It turned out that： （1）The enrichments of the magnetic susceptibility are comparatively obvious in the surface of 5 peat profiles, which began with the initial stages of the 20th century, and reached the peak value of enrichments during the 1970s to 1980s. The enrichments contents of the magnetic susceptibility in the surface are 5 to 10 times more than the below. （2）The characteristics of the enrichments of magnetic susceptibility of the five peat profiles in Changbai Mountains reflect the influences of atmospheric dust suffering from nature factors such as the prevailing west wind, and the affections of many anthropogenic activities to nature environment such as the developments of city and so on. So it proved that the magnetic susceptibility of peat is a good indicator of environmental pollutions and damages as a result of human activities in modem history.