LIBS技术的沉积物中重金属元素Zn的分析研究

doi:10.3964/j.issn.1000-0593(2020)11-3617-06

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Abstract With the rapid development of economy, the intensely deepening pollutions in the ocean and rivers have become a major issue. As a key indicator of environmental assessment, the sediments can offer important information on heavy metal pollution. Infield investigation, rapid and real-time detection method for sediments is lacking for the time being. With the advantages of fast and real-time analysis, simple sample pretreatment, multiple element detection, Laser-induced Breakdown Spectroscopy (LIBS) can meet the requirements of field sediment probe. In this paper, a portable LIBS system was developed and used for the element of Zn detection from sediment samples.The system was equipped with a Nd:YAG pulses laser as the source and a miniature optical fiber spectrometer. With a size of 371 mm×192 mm×294 mm, the system was convenient for field measurement. To quantify the Zn in sediment samples, the LIBS spectra of sediments obtained after the samples pretreatment shouldbe standardized in the first step. The best method was standardized with characteristic plasma parameters through a comparison with some typical methods to reduce the relative standard deviation (RSD) to its fifth of original data. A backpropagation artificial neural network (BPNN) with the driving factorwas adopted as the calibration model for quantitation. An R² value over 0.99 and a twice better predictive result were achieved with the single variable analysis. Also, we found that the spectral intensity of sediments was not significantly affected by drying longer than 12 minutes. Therefore, LIBS detection can be carried out after a 12-minute drying to the samples in the field investigation. The field experiment was made at 6 different sampling sites in Jiaozhou Bay using the portable LIBS system. A LIBS detection can be carried out after a 12-minute drying to the samples in the field investigation. The concentration prediction of Zn was got by using of the above methods. The results showed their coincidencein comparison with the results using Atomic Absorption Spectroscopy (AAS) method with the average relative deviation of 8.32%. The obtained results proved the performance of the portable LIBS system in field sediment sample analysis and showed the applicability for predicting Zn concentration using the standardization with characteristic plasma parameters and BPNN combined approach.

Key words：Laser-induced breakdown spectroscopy (LIBS); Portable system; Sediments; Heavy metal Zn; Quantitative analysis

Received: 2019-10-08 Accepted: 2020-02-12

ZTFLH:

O433.4

Corresponding Authors: GUO Jin-jia E-mail: opticsc@ouc.edu.cn

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http://www.gpxygpfx.com/EN/10.3964/j.issn.1000-0593(2020)11-3617-06 OR http://www.gpxygpfx.com/EN/Y2020/V40/I11/3617