沉积物中元素碳的提取、鉴定及其古气候环境意义

通过化学氧化方法提取沉积物中元素碳物质,采用拉曼光谱对其进行分析鉴定,实验结果表明:元素碳是介于单晶石墨碳和无定形碳之间的一系列物质,是一种操作上的定义;化学氧化法提取沉积物中元素碳是可靠的,控制好氧化条件和时间,则能有效去除有机碳,保留元素碳成份。鉴于目前不同工作者由于不同的实验条件和方法下得到了不同结果,我们认为确定标准样及其浓度,统一实验方法是亟待解决的问题,进而统一这种碳微粒的名称,明确其定义,以利于相关研究的横向对比和深入。而在纵向研究方面,我们利用该实验流程提取灵台黄土剖面长时间序列黄土—古土壤样的元素碳,并进行元素碳含量的测定,结果表明元素碳记录能有效揭示古气候环境变化。在不同时间尺度上,元素碳记录有不同的气候指示意义,并且与其他气候环境指标能进行较好的对比,元素碳记录为古气候环境变化提供一新的指标。

Extraction and Identification of Elemental Carbon from Sediment and Its Implications in Environment and Climate

Elemental carbon was extracted from sediment by chemical oxidation and identified by Raman spectroscopy.The experimental results indicate that elemental carbon is defined by processing,which is a continuum from single crystal graphite to amorphous carbon.Chemical oxidation is a feasible method to extract elemental carbon from sediment and it can remove organic carbon and remain elemental carbon through controlling experimental condition and time.We think that the determination of standard sample and its concentration and unification of experimental method are very important because there are different results through different experimental conditions and methods.The unification and definition of all these carbon particulates are good for transect comparison and further research in relative field.In vertical secetion,elemental carbon was extracted by the same method and determination indicates that elemental carbon record can uncover paleoclimatic and environmental changes.In different timescale,elemental carbon has different implications for climate.At the same time,elemental carbon curve show a good change trend with other climatic indicators,which indicate elemental carbon can provide another new indicator for climatic and environmental changes.