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	Interaction of Ca~(2+) and soil humic acid characterized by a joint experimental platform of potentiometric titration, UV-visible spectroscopy, and fluorescence spectroscopy
	Tang Haiming; Xiao Baohua; Xiao Peiwen
来源期刊	中国地球化学学报
ISSN	2096-0956
出版年	2021
卷号	40 期号:3 页码:2096-0956
英文摘要	Rocky desertification has become a major environmental issue in the karst region of southwestern China. Karst rocky desertification was more severe in regions of limestone soil than in adjacent regions of other soils, despite the relatively higher soil organic matter (SOM) content in limestone soil. The underlying mechanism remains ambiguous. We speculated that the geochemical characteristics of limestone soils in the karst region plays an essential role, especially the high calcium content of limestone soil. To test this hypothesis, we collected limestone soil samples from a limestone soil profile in the southwestern China karst region and extracted humic acid (HA) from these limestone soil samples. We investigated the interaction of Ca~(2+) and three HA samples on a joint experimental platform, which consists of an automatic potentiometric titrator, a UV-visible spectrometer, and a Fluorescence spectrometer. HA solutions were titrated by Ca~(2+) and optical spectra of the HA solutions were monitored during the titration experiments. The results indicated that: (1) the interaction of Ca~(2+) and HA is a combined process of adsorption and complexation. Adsorption dominated the overall distribution behavior of Ca~(2+), which could be fit by Langmuir and Freundlich isotherm models. Complexation was distinguished only when the concentration of Ca~(2+) is low; (2) the changes of UV-visible spectroscopy and excitation-emission matrix fluorescence spectroscopy spectra of HA samples when they were binding with Ca~(2+) implied the apparent molecular size and structure of HA became larger and more complex; (3) the combination of Ca~(2+) and HA plays an important role in the SOM preservation of limestone soils but the stability of the Ca-HA association was relatively weak. The present study draws attention to maintaining the relatively higher Ca~(2+) concentration in limestone soils in ecologic restoration attempts in karst regions.
英文关键词	Limestone soil Humic acid Calcium Interaction Titration UV-Vis EEM
类型	Article
语种	英语
国家	中国
收录类别	CSCD
WOS类目	Agriculture
CSCD记录号	CSCD:6980908
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/365416
作者单位	Tang Haiming, Institute of Geochemistry Chinese Academy of Sciences;;University of Chinese Academy of Sciences, State Key Laboratory of Environmental Geochemistry;;, Guiyang;;, Guizhou;;Beijing 550081;;100049.; Xiao Peiwen, Institute of Geochemistry Chinese Academy of Sciences;;University of Chinese Academy of Sciences, State Key Laboratory of Environmental Geochemistry;;, Guiyang;;, Guizhou;;Beijing 550081;;100049.; Xiao Baohua, Institute of Geochemistry Chinese Academy of Sciences, State Key Laboratory of Environmental Geochemistry, Guiyang, Guizhou 550081, China.
推荐引用方式 GB/T 7714	Tang Haiming,Xiao Baohua,Xiao Peiwen. Interaction of Ca~(2+) and soil humic acid characterized by a joint experimental platform of potentiometric titration, UV-visible spectroscopy, and fluorescence spectroscopy[J],2021,40(3):2096-0956.
APA	Tang Haiming,Xiao Baohua,&Xiao Peiwen.(2021).Interaction of Ca~(2+) and soil humic acid characterized by a joint experimental platform of potentiometric titration, UV-visible spectroscopy, and fluorescence spectroscopy.中国地球化学学报,40(3),2096-0956.
MLA	Tang Haiming,et al."Interaction of Ca~(2+) and soil humic acid characterized by a joint experimental platform of potentiometric titration, UV-visible spectroscopy, and fluorescence spectroscopy".中国地球化学学报 40.3(2021):2096-0956.