This paper designs four comparative experiments of extracting charcoals from sediment.These experiments are based on nine samples from different sedimentary environments along the Red River Drainage area,Vietnam,and three samples from Virgin Forest,three from floodplain,and others from subaqueous delta.The four experiments are respectively named dispersed by(NaPO3)6 method(method A),dispersed by HCI method(method B),HF treatment method(method C)and mixture of acetic anhydride and high concentrations of H2SO4 treatment method(method D).Results show that methods C and D are easier for counting charcoals and making the charcoal shapes clearer after preparation by HF treatment than other methods because of less impurity.But method D has the process of using mixture of acetic anhydride and concentrated sulfuric acid(9:1)to remove celluloses and dye pollen,which could cause some cellulose to be carbonized,and it is proved by the experiment data.So it is less difficult to draw a conclusion that HF treatment method(method C)is the best.In addition,different treatments also influence charcoal grain size and further to calculated concentration result.Thus,it is very important to choose a suitable treatment for charcoal extraction.As for charcoal counting,we manage to use software of NIS-Elements Br 3.0 to measure the charcoal parameters statistically in serial photos instead of manual counting under microscope.This counting method not only reduces artificial inaccuracy,but also realize the multi-parameter measurement and output,which benefit to interpret more information about palaeoenviroment,paleoclimate,vegetation.%本文设计4个不同的实验方法,以越南红河流域原始森林区、河漫滩区和水下三角洲区3个不同沉积环境下的9个样品为实验对象,对镜下碳屑不同的实验室处理方法进行对比研究,实验发现样品用六偏磷酸钠分散法(方法A)和盐酸分散法(方法B)处理后,镜下碳屑形态不易分辨,杂质多,而用氢氟酸处理法(方法C)和附加醋酸酐混合液处理法(方法D),镜下碳屑的形态清晰,杂质少,碳屑数量容易统计,但是方法D中利用醋酸酐与浓硫酸混合液去纤维素与染色过程会使纤维索碳化,结果显示碳屑浓度明显比用前3种方法处理的浓度高.以上实验结果表明方法C是最优的.另外,本研究在进行碳屑统计时,利用NIS-Elements Br 3.0软件的自动统计计数功能,不仅可以减小人为计数产生的误差,还可以实现碳屑的多参数统计,有利于古环境、古气候、古植被变化的多信息解译.
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