Heavy metals; Detection; Voltammetry; Environmental testing; Field characterization; E-Tongue; Arsenic; Cadmium; Lead; Mercury; Zinc;INDUCED BREAKDOWN SPECTROSCOPY; ANODIC-STRIPPING VOLTAMMETRY; SCREEN-PRINTED ELECTRODES; ORGANIC POLYMERS; SOILS; GROUNDWATER; SYSTEM; FLUORESCENCE; ENVIRONMENT; SUBSURFACE

Heavy metals from both natural and anthropogenic sources present a significant risk to human and environmental health. A number of methods have been developed for the detection and quantification of heavy metals. These methods include laboratory analysis, onsite testing of samples, and in situ techniques. This paper will review current and emerging technologies for site characterization with a specific focus on in situ detection of heavy metal contamination in geoenvironmental remediation projects. In addition, on-going research performed for the development of an in situ voltammetric sensor system will be presented. A number of devices exist for the efficient sampling of contaminated groundwater including the Hydropunch, BAT system, and Cone Sipper. Samples may either be sent to a laboratory for analysis with techniques such as atomic absorption spectroscopy, inductively coupled plasma-mass spectrometry, atomic emission spectroscopy, and X-ray fluorescence, or analyzed onsite using methods such as colorimetry, voltammetry, or biological based chemical sensors. For in situ analysis of heavy metals in soil, X-ray fluorescence and laser induced breakdown spectroscopy technologies have been integrated with the cone penetrometer probe. This paper further explores the feasibility of integrating electrochemical techniques based on voltammetry for the in situ detection of aqueous metal ions. The development of bismuth, gold nanoparticle, and polymer modified electrodes allow for the detection of heavy metal contaminants, including lead, cadmium, mercury and arsenic, at low part per billion levels.

Laser induced breakdown spectroscopy (LIBS); On-line analysis; Heavy metal; Enrichment; Instrument system;QUANTITATIVE-ANALYSIS; LIBS; CADMIUM; SAMPLES; LEAD

The enrichment method of heavy metal in water with graphite and aluminum electrode was studied, and combined with plasma restraint device for improving the sensitivity of detection and reducing the limit of detection (LOD) of elements. For aluminum electrode enrichment, the LODs of Cd, Pb and Ni can be as low as several ppb. For graphite enrichment, the measurement time can be less than 3 min. The results showed that the graphite enrichment and aluminum electrode enrichment method can effectively improve the LIBS detection ability. The graphite enrichment method combined with plasma spatial confinement is more suitable for on-line monitoring of industrial waste water, the aluminum electrode enrichment method can be used for trace heavy metal detection in water. A LIBS method and device for soil heavy metals analysis was also developed, and a mobile LIBS system was tested in outfield. The measurement results deduced from LIES and ICP-MS had a good consistency. The results provided an important application support for rapid and on-site monitoring of heavy metals in soil. (C) 2017 Elsevier B.V. All rights reserved.

Libs; Soil analysis; Practical powder sample holder; Quantitative powder analysis;ATOMIC EMISSION-SPECTROMETRY; SPECTROCHEMICAL ANALYSIS; PLASMA; LIBS; ABLATION; MATRIX; METALS; PB

A practical alternative of sample preparation technique is proposed for direct powder analysis using laser-induced breakdown spectroscopy (LIBS) instead of the commonly adopted treatment of pelletizing the powder. The resulted pellet is known to suffer from reduced sensitivity of emission. Besides, it may also give rise to interfering effect from the binder emission. We introduce in this report a more practical technique of using a subtarget supported micro mesh (SSMM) powder sample holder. The LIBS spectrum of standard soil powder measured with 13 mJ 1064 nm Nd:YAG laser in 0.65 kPa ambient air is shown to exhibit the sharp emission lines of all the major elements in the sample. A comparison with the emission spectra measured from the pelletized powder, the spectrum obtained using the SSMM sample holder shows distinctly superior spectral quality marked by the absence of matrix effect found in pelletized powder samples, and the much stronger intensity due to the more effective shock wave plasma induced thermal excitation process produced by the hard subtarget in the sample holder. Repeating the measurement on a number of the standard soil samples of various Pb contents is shown to yield a linear calibration line with practically zero intercept and a detection limit of less than 10 ppm. We have thus demonstrated the viability of the proposed powder sample holder for the development of practical and quantitative powder analysis in the field. (C) 2017 Elsevier B.V. All rights reserved.

First-Year Undergraduate/General; Analytical Chemistry; Atomic Spectroscopy; Lasers; Hands-On Learning/Manipulatives; Laboratory Instruction; Metals;LIBS

This laboratory introduces students to laser-induced breakdown spectroscopy (LIBS) for the analysis of metals in soil and rock samples. LIBS employs a laser-initiated spark to induce electronic excitation of metal atoms. Ensuing atomic emission allows for qualitative and semiquantitative analysis. The students use LIBS to analyze a series of standard samples that contain various elements and construct a table of emission line wavelengths for each element analyzed. Students then identify metals in various soil and rock samples. Students gain valuable experience in qualitative analysis using an important spectroscopic tool, while gaining hands-on experience with a spectrometer employing a high energy laser pulse as an excitation source. The LIBS spectrometer is applicable to upper and lower division chemistry courses and can be used as an effective demonstration tool for students in 5th to 12th grade.

Long-pulse laser induced plasmas; Life-time of plasma; Relative standard deviation; Limit of detection;

Laser induced breakdown spectroscopy with long-pulse laser(500 mu s) was used to generate plasma of soil sample in air. The spectroscopy emission characteristic of soil plasma was investigated under the low power-density conditions. Intense continuum background could not be detected (402 similar to 409 and 420 similar to 436 nm) and the long-pulse laser induced plasma had a longer overall life time (about 220 similar to 270 mu s), which was different from the dynamic characteristics using nanosecond laser and ultra short pulse laser. Besides, the spectral lines of Pb I 405. 78 nm and Cr I 425. 43 nm appeared at about 210 and 190 mu s. Intensity of Pb 1405. 78 nm and Cr I 425. 43 nm increased as time passed by, reaching to its maximum at 320 and 350 mu s, respectively. The study results showed that increased interaction time between laser and sample contributed to the formation of ""quasi-stable state plasma"". The relative standard deviation was 2. 21%similar to 6. 35% concluded by 8 times repeated experiments, which showed a better stability of soil plasma by using a long-pulse laser. The detection limits of Pb and Cr were 34. 7 and 40. 0 mg . kg(-1), respectively, which was below the trace element thresholds for Class 1 soil used in the environmental quality standard in China. Parameters characterizing a laser-induced plasma were obtained with the temperature of 6612 K and electron density of 3. 7 X 10(17) cm(-3) in the condition of long-pulse laser. Experimental results showed that it was in local thermodynamic equilibrium.

Laser-induced breakdown spectroscopy; Quantitative analysis; Standard addition method; Curve fitting; Heavy metals;

Quantitative analysis of four heavy metals Pb, Cr, Cu and Cd in soils and solid wastes using independently developed portable system of laser-inducedbreakdown spectroscopy. A Nd: YAG pulse laser with fundamental wavelength of 1 064 nm is used as the excitation source, with the single pulse energy of 100 mJ the pulse width of 6 ns, and the operating frequency 3 Hz. The echelle spectroscopy with high resolution and wide spectral range is used as the spectral separation device, and the intensified charge coupled device GOOD) as the spectral detection device in the experiment, with the detection range of 200 similar to 500 nm and a resolution of 0.08 similar to 0.12 nm. In order to improve the spectral intensity and detection sensitivity, a device of hemisphere spatially bound is used to restrain the plasma and a optical fiber with multi-channel is used collect the signal. The reception angle is 45 degrees. The laserrepetition rate is 2 Hz while the delay is 1.5 mu s, with the gate width of 1.05 ms. Standard addition method is used to effectively solve the quantitative analysis of samples of unknown matrix. The innovation lies in the fact that, a curve fit instead of a straight line fit is used in the standard addition method to quantitative analyze the heavy metals in soils and solid wastes, which effectively improve the measurement results. Especially for the low concentrations of soil samples, linear fitting can not be used in quantitative analysis, in contrast, the correlation coefficient of curve fitting is much higher, more closer to the national standard measurement methods, to meet soil pollution detection. The result of seven soils and solid wastes samples are as follows, line fitting relative error: Pb 1.26%similar to 79.38%, Cr-22. 44%similar to 82.06%, Cu 15.09%similar to 190.50%, Cd 32.76%similar to 167.96%, and curve fitting relative error respectively Pb - 4.19%similar to 11.92%, Cr-38.31%similar to 9.26%, Cu-7.24% similar to 26.86%, Cd-10.52%similar to 12.94%, the average relative error is 10.47%.

laser-induced breakdown spectroscopy; soil; magnesium; nonlinear multivariate calibration;RARE-EARTH-ELEMENTS; SAMPLES; LIBS; QUANTIFICATION; DIAGNOSIS; METALS

Laser-induced breakdown spectroscopy (LIBS) coupled with the nonlinear multivariate regression method was applied to analyze magnesium (Mg) contents in soil. The plasma was generated using a 100 mJ Nd:YAG pulsed laser, and the spectra were acquired using a multi-channel spectrometer integrated with a CCD detector. The line at 383.8 nm was selected as the analysis line for Mg. The calibration model between the intensity of characteristic line and the concentration of Mg was constructed. The traditional calibration curve showed that the concentration of Mg was not only related to the line intensity of itself, but also to other elements in soil. The intensity of characteristic lines for Mg (Mg I 383.8 nm), manganese (Mn) (Mn I 403.1 nm), and iron (Fe) (Fe I 407.2 nm) were used as input data for nonlinear multivariate calculation. According to the results of nonlinear regression, the ternary nonlinear regression was the most appropriate of the studied models. A good agreement was observed between the actual concentration provided by inductively coupled plasma mass spectrometry (ICP-MS) and the predicted value obtained using the nonlinear multivariate regression model. The correlation coefficient between predicted concentration and the measured value was 0.987, while the root mean square error of calibration (RMSEC) and root mean square error of prediction (RMSEP) were reduced to 0.017% and 0.014%, respectively. The ratio of the standard deviation of the validation to the RMSEP increased to 8.79, and the relative error was below 1.21% for nine validation samples. This indicated that the multivariate model can obtain better predicted accuracy than the calibration curve. These results also suggest that the LIBS technique is a powerful tool for analyzing the micro-nutrient elements in soil by selecting calibration and validation samples with similar matrix composition.

Laser-induced breakdown spectroscopy; Soil; Calibration curve; Chemometrics analysis;LIBS; CALIBRATION

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 LIES 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.

Laser-induced breakdown spectroscopy (LIES); Soil; Heavy metal; Chemometrics methods; Quantitative analysis;NEURAL-NETWORK; LIBS

A large number of farm lands are contaminated by heavy metals in the process of industrialization and urbanization. Precise detection of heavy metals in soil offers valid reference for prevention and recovery of heavy metals in the field. In this research, Laser induced breakdown spectroscopy (LIBS) and chemometrics methods were employed to conduct quantitative analysis of heavy metals Pb and Cd in soil. Based on the pollution extent, soil samples with 15 concentration gradients of Pb and Cd were manually made up. Then, the LIBS emission lines of all soil samples were collected firstly. In order to eliminate errors and noise of spectral data, preprocessing methods called removal of abnormal data and normalization were used. Then, characteristic lines and spectral regions of Pb and Cd were determined based on our LIES spectra and Atomic Spectra Database (ASD) of National Institute of Standards and Technology (NIST). Quantity regression models based on multiple linear regression (MLR), partial least squares regression (PLSR), least squares support vector machine (LS-SVM) and back propagation-artificial neural network (BP-ANN) were set up and their results were compared. As a result, models based on non-linear methods (LS-SVM and BP-ANN) offered a promising results than the linear methods of MLR and PLSR. The probable reason was that non-linear methods had an advantage to deal with matrix effects of soil automatically. The results indicated that LIBS coupled with multiple chemometrics methods provided a brand-new analysis approach for heavy metals accurate detection in soil and it could be considered as an effective theoretical foundation of making protection and recovery decision for soil contaminated by heavy metals.

Soil; Plant; Fertilizer; DP LIBS analysis; Orthogonal geometry; Ablative energy;SIGNAL ENHANCEMENT; PLANT MATERIALS; PLASMA; LIBS; FERTILIZERS; ABLATION; SOILS; QUANTIFICATION; CONTAMINANTS; DEPENDENCE

A soil, a plant and a fertilizer sample were investigated by double-pulse (DP) laser-induced breakdown spectroscopy (LIBS) in orthogonal beam geometry using a reheating configuration. The DP-LIBS signal enhancement was evaluated with respect to the corresponding single-pulse (SP) LIBS as a function of the interpulse delay at various ablation energies. The maximum signal enhancement measured was 155-fold when low ablation energy (4 mJ) and an interpulse delay of 10 mu s were used. At high laser energies (>= 16 mJ) and interpulse delay of 0.6 mu s, the maximum signal enhancement was up to 3-fold. The effect of excitation energies and interpulse delays on emission line intensities was discussed in the various conditions used. The emission line enhancement measured for ionic lines was always higher than that of atomic lines. Plasma excitation temperature and electron density measured as a function of interpulse delays at various ablation energies were shown to be related to the emission line intensities. (C) 2017 Elsevier B.V. All rights reserved.

LIBS; POLLUTION; CHINA

In this work, a mobile laser-induced breakdown spectroscopy (LIBS) system has been successfully applied to in situ analysis of heavy metals in soil samples. The LIBS system had two working methods, which were a fixed measuring method and a handheld method. For the fixed measuring method, a simple sample pretreatment was needed to reduce the soilmatrix effect generated by moisture and porosity. Experiments proved that this method could be used to semi-quantitatively detect heavy metals when combined with the traditional calibration curve method. The limits of detection for copper, lead, and zinc were all below 10 mg/kg, which satisfied the need of heavy metal detection in soil. Principal component analysis was used for soil classification, which helped to build appropriate calibration curves. On the basis of soil classification, accurate and rapid detection of heavy metals in soil is feasible. For the handheld method, spectrum intensity and stability decreased significantly compared with the fixed measuring method. However, by using the internal standard method, the stability of LIBS data was improved significantly to 6%. For soil samples with serious heavy-metal pollution, the measurement errors were less than 12%, which indicated that handheld LIBS was effective to monitor heavy-metal pollution in soil. The research results provide application support for rapid and on-site monitoring of heavy metals in soil. (C) 2017 Optical Society of America

INDUCED BREAKDOWN SPECTROSCOPY; OPTICAL 2ND-HARMONIC GENERATION; PULSES; NANOSECOND; IONIZATION; PLASMA; MEDIA

We observe the third-harmonic generation and second-harmonic generation together with element fluorescence from the interaction of a femtosecond laserfilament with a rough surface sample (sandy soil) in non-phase-matched directions. The harmonics prove to originate from the phase-matched surface harmonics and air filament, then scatter in non-phase-matched directions due to the rough surface. These harmonics occurr when the sample is in the region before and after the laser filament, where the laser intensity is not high enough to excite the element fluorescence. The observed harmonics are related to the element spectroscopy, which will benefit the understanding of the interaction of the laser filament with a solid and be helpful for the application on filament induced breakdown spectroscopy.

Trace radioactive pollutant; Cs in water; Cs in soil; Low pressure plasma; ITO film;SHOCK-WAVE PLASMA; SAMPLES; LIBS

An experimental study has been conducted for the practical and in situ application of laser-induced breakdown spectroscopy (LIBS) for the detection of Cs pollutant in water and soil in the nearby area of Fukushima Nuclear Power Station. The spectrochemical measurements were carried out by means of 355 nm Nd-YAG laser with N-2 and He ambient gases at atmospheric and low pressures. The soil samples were prepared by pelletizing the mixtures of 80% soil and 20% KBr while the aqueous samples were prepared as thin films electro deposited on indium tin oxide (ITO) glass. The resulted emission spectra using 0.5 kPa N-2 ambient gas shows the minimum detectable Cs concentration of 0.2 ppm and 0.3 ppm in the water and soil samples, respectively. The result of this experiment has thus demonstrated the viability of the LIBS equipment employed here as a more practical, in-situ and even mobile alternative to the standard use of gamma-ray spectroscopy using germanium detector. (C) 2017 Published by Elsevier B.V.

SIGNAL ENHANCEMENT; LIBS; DEPENDENCE; SOIL; MICROANALYSIS; EMISSION; ABLATION; LIQUIDS

Laser-induced breakdown spectroscopy (LIBS) is a technique increasingly used to perform fast semi-quantitative multi-elemental analyses of various materials without any complex sample preparation, being also suitable for in situ analyses. Few studies have been performed to understand the influence of laserwavelength on LIBS analytical performance on environmental samples. The main goal of this study was to perform a comparative elemental analysis of a number of soils, citrus leaves, and synthetic solid matrices using two different wavelengths, i.e., 532 and 1064 nm of Nd: YAG lasers, and a spectrometer coupled to a non-intensified charge-coupled device camera as the detection system. The emission lines with higher upper energy level, i.e., C I-193.03 (7.685 eV) and Si I-212.41 nm (6.616 eV), were more intense when using the 532 nm than the 1064 nm laser light, whereas the opposite occurred for elements with lower upper energy level, i.e., Ti I-336.12 nm (3.716 eV) and Fe I-368.75 nm (4.220 eV). The observed increase in LIBS signal between the two wavelengths is about 30-50%. The relationship between the line emission intensities and the used excitation wavelengths were associated to the upper level energy of the element.

laser-induced breakdown spectroscopy; plasma temperature; electron density; limit of detection;ND-YAG LASER; EMISSION

The plasma is generated by focusing a long-pulse (80 mu s) Nd:YAG laser on chromium-doped soil samples. The calibration curves are drawn using the intensity ratio of the chromium spectral line at 425.435 nm with the iron spectral line (425.079 nm) as reference. The regression coefficient of the calibration curve is 0.993, and the limit of detection is 16 mg/kg, which is 19% less than that for the case of a Q-switched laser In the method of long-pulse laser-inducedbreakdown spectroscopy, the laser-induced plasma had a temperature of 15795.907 K and an electron density of 2.988 x 10(17) cm(-3), which exceeded the corresponding plasma parameters of the Q-switched laser-induced breakdown spectroscopy by 75% and 24% respectively.

ACCURACY IMPROVEMENT; WAVELET TRANSFORM; LIBS; SPECTROMETRY; PEAKS

The complex and serious spectral interference makes it difficult to detect trace elements in soil using laser induced breakdown spectroscopy (LIBS). To address it, LIBS-assisted by laser-induced fluorescence (LIES-LIP) was applied to selectively enhance the spectral intensities of the interfered lines. Utilizing this selective enhancement effect, all the interference lines could be eliminated. As an example, the Pb I 405.78 nm line was enhanced selectively. The results showed that the determination coefficient (R-2) of calibration curve (Pb concentration range = 14-94 ppm), the relative standard deviation (RSD) of spectral intensities, and the limit of detection (LOD) for Pb element were improved from 0.6235 to 0.9802, 10.18% to 4.77%, and 24 ppm to 0.6 ppm using LIBS-LIF, respectively. These demonstrate that LIBS-LIF can eliminate spectral interference effectively and improve the ability of LIBS to detect trace heavy metals in soil.

Laser-induced breakdown spectroscopy; Orthogonal dual-pulse; Spectral enhancement; Signal-to-background ratio; Plasma temperature; Electron density;OPTICAL-EMISSION; ENHANCEMENT

In order to improve the detection sensitivity and spectral characteristic of laser-induced breakdown spectroscopy (LIES), re-heating orthogonal dual-pulse configuration is adopted to analyze Fe, Pb, Ca and Mg contained in the sample and soil sample contained different concentrations of heavy mental Cr. Variation relationship between spectral intensity, signal-to-background(SBR) of four characteristic spectral lines Fe I : 404. 581 nm, Pb I : 405. 78 nm, Ca I 422. 67 rim and Mg I : 518. 361 nm and time interval of two laser pulses is discussed, the best time interval of two laser pulses is obtained 1. 0 s. In the condition of single pulse and dual-pulse, the enhancement factor of spectral intensity of four characteristic spectral lines Fe I : 404. 581 nm, Pb I : 405. 78 nm, Ca I : 422. 67 nm and Mg I : 518. 361 nm is respectively 2. 23, 2. 31, 2. 42 and 2. 10; The time evolution characteristic of spectral intensity of characteristic spectral lines Fe I : 404. 581 nm and Ca I : 422. 67 rim is considered, and also the variation relationship between spectral acquisition delay time and SBR of-four characteristic spectral lines, dual-pulse can prolong decay time of spectral intensity and improve the SBR of characteristic spectral lines; time evolution characteristic of plasma temperature and electron density is compared in the condition of single pulse and dual-pulse, maximum elevation of plasma temperature is found to be 730 K, and the maximum increase of electron density is 1. 8 X 10(16) cm(-3). The limits of detection of heavy mental Cr are obtained 38 and 20 mu g center dot g(-1) respectively in condition of single and double pulse, limit of detection of Cr is reduced approximately 2 times by the condition of re-heating orthogonal dual pulse. Results above indicate that reheating orthogonal dual-pulse can improve detection sensibility and spectral characteristic of LIBS technique, which provides an effective method for decreasing the limit of detection of elements.

Stand-off LIBS; heavy metals; environmental samples;INDUCED BREAKDOWN SPECTROSCOPY

Interest in the use of laser-based sensors operating in stand-off mode is increasing due to the wide range of options offered in the evaluation of distant targets. In this work, a stand-off laser induced breakdown spectroscopy (ST-LIBS) system has been developed and demonstrated to determine the heavy elements in soil samples. Initially, different parameters of the device have been optimized in ambient atmosphere and tested for quantitative analysis of Nickel and Chromium at two different stand-off distances (1 m and 6 m). The prepared concentrations were in the range of 100 ppm to 600 ppm. The laser energy of 150 mJ was maintained through out the experiment and to obtain a real time situation the target was in static state.

COASTAL ZONE; TSUNAMI; CONTAMINATION; THAILAND

In this work, LIBS technique has been used for detection of heavy metal especially iron, Fe in soil sample. As there are a large number of emission spectral lines due to Fe and other constituents in soil, this study is intended to identify emission spectral lines of Fe and finally to find best fit emission spectral lines for carrying out a qualitative and quantitative analysis. LIBS apparatus used in this work consists of a laser system (Neodymium Yttrium Aluminum Garnet, Nd-YAG: Quanta Ray; LAB SERIES; 1,064 nm; 500 mJ; 8 ns) and an optical multichannel analyzer (OMA) system consisting of a spectrograph (McPherson model 2061; 1,000 mm focal length; f/8.6 Czerny-Turner) and an intensified charge coupled device (ICCD) 1024x256 pixels (Andor I*Star). The soil sample was collected from Banda Aceh city, Aceh, Indonesia. For spectral data acquisition, the soil sample has been prepared by a pressing machine in the form of pellet. The laser beam was focused using a high density lens (f=+150 mm) and irradiated on the surface of the pellet for generating luminous plasma under 1 atmosphere of air surrounding. The plasma emission was collected by an optical fiber and then sent to the optical multichannel analyzer (OMA) system for acquisition of the emission spectra. It was found that there are many Fe emission lines both atomic lines (Fe I) and ionic lines (Fe II) appeared in all detection windows in the wavelength regions, ranging from 200 nm to 1000 nm. The emission lines of Fe with strong intensities occurs together with emission lines due to other atoms such as Mg, Ca, and Si. Thus, the identification of emission lines from Fe is complicated by presence of many other lines due to other major and minor elements in soil. Considering the features of the detected emission lines, several emission spectral lines of Fe I (atomic emission line), especially Fe I 404.58 nm occurring at visible range are potential to be good candidate of analytical lines in relation to detection heavy metal pollution, Fe, in soil sample.

Carbon dioxide laser; heavy metals; laser-induced breakdown spectroscopy; soil;METASTABLE HE ATOMS; SAMPLES; PLASMA; POLLUTION; INPUTS; GAS

A novel method of laser-induced plasma spectroscopy utilizing a pulsed transversely excited atmospheric CO2 laser has been developed for the high-sensitivity determination of heavy metals in soil. A coarse metal powder was used to trap the soil and to assist with plasma generation. When the CO2 laser(10.6 mu m, 1.5J, 200ns) was irradiated on the metal and soil powder, a high-temperature and long-lifetime luminous plasma was induced. Fine particles of soil were dissociated and were excited in the plasma region. The method was used for the rapid determination of Cr, Pb, and Hg in loam. The limits of detection for Cr, Pb, and Hg were approximately 0.8, 15, and 0.7mg/kg, respectively.