杨欢^1,,
曾蒙秀^1,,,
彭海军^2,,,
李凯³,
李凤全¹,
朱丽东¹,
邓伯龙⁴,
廖梦娜³,
倪健³
1. 浙江师范大学地理与环境科学学院, 浙江 金华 321004
2. 中国科学院地球化学研究所环境地球化学国家重点实验室, 贵州 贵阳 550081
3. 浙江师范大学化学与生命科学学院, 浙江 金华 321004
4. 贵州省湿地保护中心, 贵州 贵阳 550001

基金项目: 国家自然科学基金面上项目（批准号：41971111和41773140）和国家重点基础研究发展计划项目（批准号：2016YFC0502101）共同资助


详细信息

作者简介: 杨欢, 女, 25岁, 硕士研究生, 自然地理学专业, E-mail:helenyang4@outlook.com

通讯作者: 曾蒙秀, E-mail:mengxiuzeng@zjnu.edu.cn; 彭海军, E-mail:penghaijun@mail.gyig.ac.cn

中图分类号: P534.63;P941.78

收稿日期:2020-03-12
修回日期:2020-06-28
刊出日期:2020-09-30

Application of XRF core scanning method in Late Holocene environment change study derived from a peat core from southwestern Guizhou, Southwestern China

Yang Huan^1,,
Zeng Mengxiu^1,,,
Peng Haijun^2,,,
Li Kai³,
Li Fengquan¹,
Zhu Lidong¹,
Deng Bolong⁴,
Liao Mengna³,
Ni Jian³
1. College of Geography and Environment Sciences, Zhejiang Normal University, Jinhua 321004, Zhejiang
2. State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, Guizhou
3. College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, Zhejiang
4. Wetland Protection Center of Guizhou Province, Guiyang 550001, Guizhou


More Information

Corresponding authors: Zeng Mengxiu,E-mail:mengxiuzeng@zjnu.edu.cn ; Peng Haijun,E-mail:penghaijun@mail.gyig.ac.cn

MSC: P534.63;P941.78

--> Received Date: 12 March 2020
Revised Date: 28 June 2020
Publish Date: 30 September 2020


摘要
摘要:文章选取发育于贵州喀斯特地区的兴义泥炭为研究对象，对钻孔上部300 cm岩芯进行高分辨率XRF连续扫描，并测定了样品含水量、色度（亮度L^*、红度a^*、黄度b^*）和碳酸盐含量。通过对Rb、Ti、Zr、Al、Si、Ca、Sr、Mg等元素含量及其比值、色度和其他代用指标的综合分析，结合主成分分析方法，探讨XRF岩芯扫描在兴义泥炭研究中使用的可行性，并进一步分析兴义泥炭化学元素的来源、指示意义及所记录的古环境演化过程。基于AMS¹⁴C测年构建的年代框架，发现：1）XRF岩芯扫描的Ca元素含量与气量法测定的碳酸盐含量具有较好的一致性。XRF岩芯扫描和分光测色计获得的L^*、b^*相关性高，尽管这两种方法获得的a^*存在差异，但其数值表现上相似性仍较高；2）晚全新世以来兴义泥炭的地球化学元素主要来源于周边碳酸盐岩风化、淋溶、随流水搬运而最终沉积到湿地的物质；3）兴义泥炭Sr/Ca比值处于高值，Si/Al、Rb/Sr比值处于低值时，气候偏干，反之则指示气候偏湿润。此外，兴义泥炭Al、Si、Ca、Sr、Mg、Rb/Sr、Si/Al、Sr/Ca的变化趋势与烧失量、腐殖化度等具有较好的一致性；4）晚全新世以来兴义地区总体上呈现出由湿润向干转变的趋势，3270~2700 cal.a B.P.由湿润持续转干，2300~1670 cal.a B.P.降水持续减少，与西南季风主控区众多古环境记录能较好地对应，并揭示了2700~2300 cal.a B.P.降水稳步增加的过程。对兴义泥炭进行XRF岩芯扫描能挖掘其蕴含的物质来源、物质变化特征等多方面信息，有助于拓展XRF岩芯扫描分析方法在泥炭沉积中的应用，并能深化对西南地区古环境演化历史的认识及丰富泥炭研究档案。
关键词: 贵州泥炭/
XRF岩芯扫描/
元素地球化学/
喀斯特地貌/
古环境重建

Abstract:X-ray fluorescence (XRF) core scanning is a method that has been widely used in loess, marine and lacustrine sediments. The application of this method in peat needs to be further enhanced. In this study, a 300-cm peat drilling core XY1801 (25.28°N, 104.82°E; 1317 m. a.s.l.) from Xingyi peatland in karst region, southwestern Guizhou Province was selected to scan with high resolution XRF. Furthermore, the water content, chromaticity (L^*, a^*, b^*) and carbonate content in Xingyi peat were also measured. Based on the analysis of contents and ratios of Rb, Ti, Zr, Al, Si, Ca, Sr, Mg, chromaticity, humification and other proxies of Xingyi peat, and in combination of the principal component analysis method, this paper discussed the material source of elements, the environmental significances of element contents/ratios, and the recorded paleoenvironment evolution history in and around Xingyi peatland during Late Holocene. Based on the chronological framework constructed by AMS¹⁴C dating, the results are shown below. (1) XRF core scanning analysis can achieve ideal results in the research of Xingyi peat, and the element records greatly corresponding to the data obtained by traditional methods. The content of Ca from XRF core scanning coincides well with the carbonate content measured by gas volume method. Furthermore, the variation trend of L^* and b^* obtained by XRF core scanning and colorimeter is also coincident. The correlation coefficient of L^* observed from these two methods is 0.99 (P < 0.01), and that of b^* is 0.91 (P < 0.01). Moreover, the measured results of a^* from these two methods have slightly different due to the influence of sample characteristics and the difference during experimental process. However, the numerical similarity of a^* is still high, the correlation coefficient is 0.92 at the 0.01 significance level. (2) Through the analysis of the contents of geochemical elements in Xingyi peat, carbonate weathering process and weathering profiles in karst region, it can be found that the sources of geochemical elements in Xingyi peat are mainly from proximal material. Geochemical elements separated out from the surrounding carbonate and eventually deposited in the peatland during the processes of weathering, leaching, transporting, depositing and illuviation. (3) The correlation coefficient between Sr/Ca ratio and Ca element content is-0.38 (P < 0.01), and the correlation coefficient of Sr/Ca ratio and Sr element content is-0.03 (P < 0.01), indicating that Ca element content has more significant influence on Sr/Ca ratio; the correlation between Si/Al ratio and Si element content in Xingyi peat (R²=0.33, P < 0.01) is higher than that between Si/Al ratio and Al element content (R²=-0.02, P < 0.01), thus the ratio is more obviously affected by Si element; the Rb/Sr ratio is also more related to Rb element. It can be concluded that the climate is dry when Sr/Ca ratio is in high value, and the ratios of Rb/Sr and Si/Al are in low values; and vice versa. (4) Based on the comparative analysis of Ca, Mg, Al, Si, Rb/Sr, Si/Al, Sr/Ca, LOI, humification degree and carbon accumulation rate in Xingyi peat, it is found that the precipitation in Xingyi area decreased during 3270~2700 cal. a B. P, increased steadily during 2700~2300 cal.a B. P., and decreased continuously during 2300~1670 cal.a B. P. (5) Through the principal component analysis of the main elements in Xingyi peat, it can be observed that the first principal component (F1) of Xingyi peat includes Al, Si, Mg, is as ideal index can be considered as a comprehensive factor reflecting precipitation and runoff in the basin; the second principal component (F2) includes Sr, Ca and other elements, is closely related to carbonate input and bedrock in and around of the surrounding karst landform area; the third principal component (F3) includes Rb, Zr and Ti, is related to stable particles. (6) The climate evolution history reconstructed from Xingyi peat is consistent with G.bulloides percentage in Hole 723A from the Arabian Sea and several paleoenvironmental records from southwestern monsoon-dominated region, which all reflect that the climate environment is generally dry during the Late Holocene. Interestingly, the records of Xingyi peat reflect that 2700~2300 cal.a B. P. was a humid period lasting for nearly 400 years, which are also supported by many previous researches, while are not significant in some sporopollen records. XRF core scanning and the research of Xingyi peat in karst area is helpful to deepen the understanding of the paleoclimate in subtropical Southwest China, and extend the utilization of XRF core scanning in peat record.
Key words:Guizhou peat/
XRF core scanning/
element geochemistry/
karst landscape/
paleoenvironmental reconstruction



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