光谱学与光谱分析, 2017, 37 (9): 2879, 网络出版: 2017-10-16
应用激光诱导击穿光谱对土壤中多元素同时定量分析
Laser-Induced Breakdown Spectroscopy for Simultaneous Quantitative Analysis of Multi-Elements in Soil
激光诱导击穿光谱 土壤 定标曲线法 化学计量学分析 Laser-induced breakdown spectroscopy Soil Calibration curve Chemometrics analysis
摘要
土壤元素的丰缺是对土壤养分检测、 农业按需种植和科学施肥的依据, 是精准农业农情信息感知技术检测的关键点, 更为农业生态、 高效和优质生产提供理论指导。 该研究运用激光诱导击穿光谱(LIBS)技术结合定标曲线法和偏最小二乘回归(PLSR)方法对土壤中的Al, Fe, Mg, Ca, Na和K多种元素同时进行定量分析。 利用LIBS检测仪获取了五种标准土壤样品(国家编号: GBW07446, GBW07447, GBW07454, GBW07455和GBW07456)的LIBS数据之后, 将每种土壤的多条谱线平均处理来消除试验误差。 通过分析所获取的土壤LIBS谱线信息, 选取了Al, Fe, Mg, Ca, Na和K元素的特征分析谱线和分析光谱区间, 并利用谱线的峰值信息和分析光谱区间内的单个或多个谱峰的积分信息(峰面积)与对应元素浓度拟合并建立定标曲线。 结果表明, 基于谱峰的峰面积建立的定标曲线的线性关系优于利用峰值信息建立的定标曲线(Fe除外)。 同时, 针对所选的分析光谱区间和元素的浓度信息, 运用PLSR建立定量分析模型, 其结果明显要优于定标曲线的分析精度, 这也表明LIBS技术结合化学计量学分析在未来光谱化学分析领域有很大应用前景。 研究的结果不仅为现代农业的土壤养分空间分布检测和农田精准施肥技术的应用起指导作用, 还为田间使用的便携式LIBS土壤检测仪的开发奠定了理论基础。
Abstract
Abundance or deficiency of soil elements is an expression of soil fertility. Rapid detection of elements in soil is a key point of front information acquirement tools in precision agriculture, and it also provides a theoretical basis for pollution prevention of soil heavy metal and sustainable development of agriculture. This research focused on using laser-induced breakdown spectroscopy LIBS) technique combined with calibration curve and chemometrics method to conduct the simultaneous quantitative analysis of multi-elements (Al, Fe, Mg, Ca, Na and K) in soil. First of all, five certified reference materials (CRM) of soil numbered GBW07446, GBW07447, GBW07454, GBW07455, GBW07456 were ablated by a laboratorial LIBS setup in air. 50 LIBS spectra of each type of soil were averaged to reduce the error in experiment process. By integrating the acquired LIBS emission spectra and atomic spectra database from national institute of standards and technology (NIST), analytical spectral lines and corresponding spectral regions were identified. Then, calibration curves of the intensity of a peak and integrated intensity of a peak or several peaks (peak area) coupling with the element content s were fitted. The results indicated that the linear relation from the calibration curves fitted by peak areas and element contents were superior to the calibration curves fitted using intensity of a peak and element contents (except the Fe). Meanwhile, partial least-squares regression (PLSR) was employed to build the quantitative model by using the selected spectral regions and corresponding element contents, which offered a promising result with relatively high RP and showed more advantages than the calibration curve method. The approach revealed that LIBS technology combined with chemometrics methods displayed a bight prospect in the field of spectrochemical analysis. The achievements of the research not only provide a guide for detecting soil nutrient spatial distribution and precision fertilization technique, but also lay a theoretical foundation for developing the portable LIBS detector used in the field.
余克强, 赵艳茹, 刘飞, 何勇. 应用激光诱导击穿光谱对土壤中多元素同时定量分析[J]. 光谱学与光谱分析, 2017, 37(9): 2879. YU Ke-qiang, ZHAO Yan-ru, LIU Fei, HE Yong. Laser-Induced Breakdown Spectroscopy for Simultaneous Quantitative Analysis of Multi-Elements in Soil[J]. Spectroscopy and Spectral Analysis, 2017, 37(9): 2879.