基于漫反射光谱的铁氧化物定量分析在南方黄土中的适用性研究

发布时间：2018-11-20 14:24

【摘要】：基于漫反射光谱(DRS)的铁氧化物定量分析已用于北方黄土的研究,而在南方黄土中的适用性尚不清楚。本文选取江西九江黄土为研究对象,采用柠檬酸钠-重碳酸钠-连二亚硫酸钠(CBD)方法去除其中的游离铁,以此为基体分别加入不同比例的赤铁矿和针铁矿,通过多元线性回归方法建立了标样的铁氧化物含量与光谱反射率之间的校准方程。经检验,校准方程应用于未经CBD处理的剖面天然样品时,获得的赤铁矿含量较准,而针铁矿含量不准。原因可能在于:(1)混合体系中,赤铁矿与针铁矿互为基体,赤铁矿对针铁矿的干扰远大于针铁矿对赤铁矿的影响,这种差异在南方地区尤为明显;(2)CBD处理不能完全清除南方黄土中的针铁矿,可能与样品中含有部分结晶较好、粒度较粗的针铁矿有关,这也增加了针铁矿定量分析的不准确性;(3)铝的同晶替代现象对南方黄土影响更为显著,其中受晶格结构等影响,针铁矿的铝替代量比赤铁矿更大,可能对定量分析结果的准确性影响也更大。因而在南方黄土中,基于DRS的铁氧化物定量分析方法对于赤铁矿是适用和有效的,对于针铁矿的应用则需要慎重。
[Abstract]:Quantitative analysis of iron oxides based on diffuse reflectance spectroscopy (DRS) has been applied to the study of loess in northern China, but its applicability in southern loess is still unclear. In this paper, Jiujiang loess in Jiangxi Province was selected as the research object. The free iron was removed by the (CBD) method of sodium citrate, sodium bicarbonate and sodium bisulfite, and hematite and goethite were added as the matrix, respectively. The calibration equation between the iron oxide content and the spectral reflectance of the standard sample was established by multivariate linear regression method. The results show that when the calibration equation is applied to the natural samples without CBD treatment, the hematite content obtained is more accurate than that of goethite content. The reasons may be as follows: (1) in the mixed system, hematite and goethite are mutual matrix, the interference of hematite to goethite is much greater than that of goethite to hematite, especially in the southern region; (2) CBD treatment can not completely remove goethite from loess in southern China, which may be related to the existence of some goethite with good crystallization and coarse grain size in the sample, which also increases the inaccuracy of quantitative analysis of goethite. (3) the homocrystalline substitution of aluminum has a more significant effect on loess in southern China, among which the quantity of aluminum substitution of goethite is greater than that of hematite, and the accuracy of quantitative analysis may be more affected by the lattice structure. Therefore, the quantitative analysis method of iron oxide based on DRS is applicable and effective for hematite in southern loess, and the application of goethite needs caution.
【作者单位】：南京大学地理与海洋科学学院;
【基金】：国家自然科学基金(41571188;41671191;41690111;41673095)
【分类号】：S151.9

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