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滇池流域宝象河水库沉积物粒度分布特征及其环境记录
1, 1,2, 3, 1, 1,2

(1.nanjingshifandaxue dilikexuexueyuan, nanjing 210023; 2.xunidilihuanjingjiaoyubuzhongdianshiyanshi, nanjing 210023; 3.shengtaihuanjingbuhuanjinggongchengpingguzhongxin, beijing 100012)

;;;—标准偏差法;

Characteristics of Distribution of Sediment Particle Size and Its Environmental Records in Baoxianghe Reservoir of the Dianchi Basin
CHEN Yan1, WANG Yanhua1,2, YE Bin3, SUN Tian1, ZHANG Maoheng1,2

(1.school of geography science, nanjing normal university, nanjing 210023, china; 2.state key laboratory cultivation base of geographical environment evolution, nanjing 210023, china; 3.appraisal center for environment & engineering, ministry of environmental protection, beijing 100012, china)

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沉积物粒度特征不仅能指示沉积物的来源和迁移方式,还可以揭示不同历史时期区域暖湿变化。为研究滇池流域宝象河水库沉积物粒度的垂向变化特征及其记录的环境变化信息,以滇池宝象河水库岩芯沉积物粒度为研究对象,利用Sahu判别式对沉积物沉积环境进行了判别,并用粒径—标准偏差法分析沉积物中的环境敏感组分。研究结果表明:(1)宝象河水库岩芯沉积物中粗粉砂质(16~64 μm)含量最高,为39.6%; 黏土质(<4 μm)和细粉砂质(4~16 μm)含量相当,合计50.3%; 砂质(>64 μm)含量最低(10.1%)。不同粒级组分随着深度变化而变化,黏土质和细粉砂质含量随埋藏深度而增加,粒径在16 μm以上的粗颗粒随埋藏深度而减小。(2)沉积物粒度基本参数特征表明沉积物分选性差,偏度属于极负偏或负偏,峰态为中等峰态或峰态宽平,平均粒径介于5.56~6.94 μm。(3)Sahu判别式判别沉积环境推断入库河流不连续。粒径—标准偏差法提取宝象河水库沉积物中的敏感组分结果揭示研究区沉积环境水动力条件有变高的趋势。B组分对沉积环境变化响应敏感,并且降水量对研究区沉积物粒径的影响显著。
The particle size characteristics of sediments can not only indicate the source and migration pattern of sediments, but also reveal the regional warm and humid changes in different historical periods. In this study, the sediments from Baoxianghe Reservoir of the Dianchi Basin were taken as the research object in order to study the vertical variation characteristics of sediment particle size and the recorded environmental change information. The Sahu discriminant method was used to identify the sedimentary environment. The environmental sensitive components in the sediments were analyzed by the grade-standard deviation method. The results show that:(1)the content of coarse silt(16~64 μm)in the sediments was the highest(39.6%); the contents of clay(<4 μm)and fine silty(4~16 μm)were the same, with a total of 50.3%. The content of sandy(>64 μm)was the lowest(10.1%); the contents of clay and fine silty increased with the burial depth, and the coarse particles with particle size of 16 μm or more decreased with the burial depth;(2)the characteristics of the basic parameters of sediment particle size indicated that the sediment had poor sorting, the skewness was extremely negative or negative, the kurtosis was medium or wide and flat, and the average particle size was between 5.56~6.94 μm;(3)we deduced from the results of Sahu discriminant that the inflow stream of the Baoxianghe Reservoir might be discontinuous; the sensitive components by the grade-standard deviation method revealed that the hydrodynamic conditions of the sedimentary environment in the study area tended to be higher; component B was sensitive to the change of sedimentary environment; the precipitation had the significant effect on the particle size of sediments in this study area.
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