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Abstract: Applications of laser-induced breakdown spectroscopy (LIBS) have been growing rapidly and continue to be extended to a broad range of materials. This paper reviews recent application of LIBS for the analysis of geological and environmental materials, here termed "GEOLIBS" . Following a summary of fundamentals of the LIBS analytical technique and its potential for chemical analysis in real time, the history of the application of LIBS to the analysis of natural fluids, minerals, rocks, soils, sediments, and other natural materials is described. [Copyright &y& Elsevier]

Abstract: A large suite of natural carbonate, fluorite and silicate geological materials was studied using laser-induced breakdown spectroscopy (LIBS). Both single- and double-pulse LIBS spectra were acquired using close-contact benchtop and standoff (25 m) LIBS systems. Principal components analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were used to identify the distinguishing characteristics of the geological samples and to classify the materials. Excellent discrimination was achieved with all sample types using PLS-DA and several techniques for improving sample classification were identified. The laboratory double-pulse LIBS system did not provide any advantage for sample classification over the single-pulse LIBS system, except in the case of the soil samples. The standoff LIBS system provided comparable results to the laboratory systems. This work also demonstrates how PCA can be used to identify spectral differences between similar sample types based on minor impurities. [Copyright &y& Elsevier]

Abstract: Laser-induced breakdown spectroscopy (LIBS) is a simple atomic emission spectroscopy technique capable of real-time, essentially non-destructive determination of the elemental composition of any substance (solid, liquid, or gas). LIBS, which is presently undergoing rapid research and development as a technology for geochemical analysis, has attractive potential as a field tool for rapid man-portable and/or stand-off chemical analysis. In LIBS, a pulsed laser beam is focused such that energy absorption produces a high-temperature microplasma at the sample surface resulting in the dissociation and ionization of small amounts of material, with both continuum and atomic/ionic emission generated by the plasma during cooling. A broadband spectrometer-detector is used to spectrally and temporally resolve the light from the plasma and record the intensity of elemental emission lines. Because the technique is simultaneously sensitive to all elements, a single laser shot can be used to track the spectral intensity of specific elements or record the broadband LIBS emission spectra, which are unique chemical ‘fingerprints’ of a material. In this study, a broad spectrum of geological materials was analyzed using a commercial bench-top LIBS system with broadband detection from ∼200 to 965nm, with multiple single-shot spectra acquired. The subsequent use of statistical signal processing approaches to rapidly identify and classify samples highlights the potential of LIBS for ‘geochemical fingerprinting’ in a variety of geochemical, mineralogical, and environmental applications that would benefit from either real-time or in-field chemical analysis. [Copyright &y& Elsevier]

Abstract: The major element chemistry was determined for surface waters from four watersheds in Central Panama during the 2005 dry season to ascertain geochemical patterns resulting from differing geology and human influences as well to estimate chemical denudation rates for this montane region of tropical rain forest. The Upper Rio Chagres (580km2), Rio Pequini (281km2) and Rio Cuango (175km2) watersheds are formed on a geologically mixed terrain that consists of strongly hydrothermally altered andesite and volumetrically subordinate mafic-intermediate volcanic rocks and felsic intrusive lithologies, whereas the Rio Pacora watershed (374km2) is developed largely on gabbroic and dioritic lithologies. The headwater areas of all four river basins lie in pristine tropical rainforest, with the Rio Cuango, Rio Pequini and Rio Pacora subject to varying degrees of different land uses in their middle to lower reaches. Values of pH for the four watersheds are near neutral to slightly alkaline (7.0–8.5), DO saturation is high (typically >90%) and dissolved solute contents of the rivers and tributary streams are low (SPC=130±31μS/cm), documenting the overall pristine quality of the waters in all four basins. Cluster analysis, supported by a comparison of elemental variations, indicates a broad geochemical similarity of rivers and streams in the four watersheds, but also reveals subtle differences that can be attributed to lithologic control rather than anthropogenic influences. Low-order streams in the Pacora watershed have distinctly higher TDS values plus silica and Ca2+ concentrations than those forming in the mixed lithology terrain. Streams and rivers developed on mafic terrain are also slightly more enriched in total dissolved cations (TZ+) and , relative to silica, than streams and rivers developed in the mixed lithology terrain. Potassium concentrations are uniformly low, and like Mg2+ and Na+, are similar in both terrains. Calcium/Mg ratios for all watersheds are lower than the world river average, indicating the importance of the weathering of Mg-rich minerals. The Ca/Na, HCO3/Na and Mg/Na ratios for the Rio Pacora streams and rivers fall within the mid-range of what has been observed globally for other streams/rivers draining mafic rocks. The chemical weathering rate calculated is 108tons/km2/a, which is about 40% of the physical denudation rate for the Upper Rio Chagres watershed of 275–289tons/km2/a. The results of this study document that both chemical and physical erosion rates within tropical montane watersheds in central Panama are significant in a global context. [Copyright &y& Elsevier]

Abstract: Laser-induced breakdown spectroscopy (LIBS) provides an alternative chemical analytical technique that obviates the issues of sample preparation and sample destruction common to most laboratory-based analytical methods. This contribution explores the capability of LIBS analysis to identify carbonate and silicate minerals rapidly and accurately. Fifty-two mineral samples (18 carbonates, 9 pyroxenes and pyroxenoids, 6 amphiboles, 8 phyllosilicates, and 11 feldspars) were analyzed by LIBS. Two composite broadband spectra (averages of 10 shots each) were calculated for each sample to produce two databases each containing the composite LIBS spectra for the same 52 mineral samples. By using correlation coefficients resulting from the regression of the intensities of pairs of LIBS spectra, all 52 minerals were correctly identified in the database. If the LIBS spectra of each sample were compared to a database containing the other 51 minerals, 65% were identified as a mineral of similar composition from the same mineral family. The remaining minerals were misidentified for two reasons: 1) the mineral had high concentrations of an element not present in the database; and 2) the mineral was identified as a mineral with similar elemental composition from a different family. For instance, the Ca–Mg carbonate dolomite was misidentified as the Ca–Mg silicate diopside. This pilot study suggests that LIBS has promise in mineral identification and in situ analysis of minerals that record geological processes. [Copyright &y& Elsevier]

Abstract: Laser induced breakdown spectroscopy (LIBS) is a simple spark spectrochemical sensor technology in which a laser beam is directed at a sample surface to create a high-temperature microplasma and a detector used to collect the spectrum of light emission and record its intensity at specific wavelengths. LIBS is an emerging chemical sensor technology undergoing rapid advancement in instrumentation capability and in areas of application. Attributes of a LIBS sensor system include: (i) small size and weight; (ii) technologically mature, inherently rugged, and affordable components; (iii) real-time response; (iv) in situ analysis with no sample preparation required; (v) a high sensitivity to low atomic weight elements which are difficult to determine by other field-portable sensor techniques, and (vi) point sensing or standoff detection. Recent developments in broadband LIBS provide the capability for detection at very high resolution (0.1nm) of all elements in any unknown target material because all chemical elements emit in the 200–980nm spectral region. This progress portends a unique potential for the development of a rugged and reliable field-portable chemical sensor that has the potential to be utilized in variety of geochemical, mineralogical, and environmental applications. [Copyright &y& Elsevier]

Laser-induced breakdown spectroscopy (LIBS) is a simple, straightforward, and versatile form of atomic emission spectroscopy that focuses a rapidly-pulsed laser beam onto a sample to form a plasma containing its constituent elements and then uses spectral analysis of the emitted light to detect the elements present. In theory, LIBS is capable of qualitative, semi-quantitative, and quantitative analysis of all elements in the periodic table. LIBS can be performed in the laboratory or outside in the ambient environment for on-site analysis in situ; LIBS can also be used for rapid microscale compositional imaging. This review first presents a description of the LIBS technique and then discusses and illustrates through a historic literature review how LIBS has been used to analyze gases, natural waters, minerals, rocks, sediments, and soils. Given the persistent need of analytical instrumentation for the rapid chemical analysis of geologic materials in the field, and the capability of LIBS to analyze any type of sample in real time with little to no preparation, there is a vast potential for the routine application of LIBS across a broad spectrum of the geosciences that is as yet only minimally realized. [Display omitted] • LIBS has specific advantages for rapid chemical analysis in the laboratory and the field, plus vast potential for application across geosciences. • LIBS principles, technology, and chemometric methods for data analysis are described. • The applications of LIBS is reviewed for the chemical analysis of different types of geological media. • Recent trends are highlighted for chemical imaging and microscale elemental analysis minerals and rocks by LIBS. [ABSTRACT FROM AUTHOR]

The first part of this review describes laser-induced breakdown spectroscopy (LIBS) instrumentation for in situ measurement outside the laboratory, both prototype instruments and commercially available analyzers that can be operated by a single individual. Two types of devices are described – (i) field-portable type systems consisting of multiple units connected by an umbilical (fp LIBS) and (ii) handheld analyzers (h LIBS). The performance of these two types of LIBS systems is compared with that of its primary competitor technology portable X-ray fluorescence spectroscopy (p XRF). The second part of the article reviews the results of both fp LIBS and h LIBS obtained in both research settings and for practical applications in various sectors where speed of analysis is often crucial. These include compositional screening of natural and manufactured materials, quality control of manufacturing processes, identification of environmental contaminants, biomedical diagnostics, forensic analysis, and hazardous material identification in the industrial, environmental, geological, cultural heritage, agricultural, biological, nuclear and security sectors. The review concludes by highlighting the key trends and challenging future directions in making LIBS technology readily accessible for applications that demand easy portability and fast analysis outside of the laboratory with instruments of compact dimensions and low weight but high performance, crucial features required for any portable device. Unlabelled Image • Overview of field-portable and handheld LIBS instrumentation transportable by a single person. • Field-portable LIBS in non-commercialized suitcase and backpack prototype instrumentation. • Recent commercial handheld LIBS instrumentation. • Applications of field-portable and handheld LIBS in a variety of research and commercial areas. [ABSTRACT FROM AUTHOR]

Tropical small mountainous rivers (SMRs) are increasingly recognized for their role in the global export of dissolved organic carbon (DOC) to the oceans. Here we utilize the Isthmus of Panama as an ideal place to provide first-order estimates of DOC yields across a wide assemblage of bedrock lithologies and land cover practices. Samples for dissolved organic carbon (DOC) analysis were collected across Panama along an E–W transect from the central Panama area to the Costa Rican border for 24 mainstem rivers, 3 large tributary rivers, and one headwater stream. Sampling occurred during both the wet and the dry seasons. DOC concentrations during the wet season are higher than during the dry season in all but three of the rivers. Concentrations vary greatly from river to river and from season to season, with values as low as 0.64 mg l −1 to greater than >25 mg l −1 with the highest concentrations observed for the rivers draining Tertiary marine sedimentary rocks in the Burica and Azuero peninsulas. DOC yields from Panamanian rivers (2.29–7.97 tons/km 2 /y) are similar to or slightly lower than those determined for other tropical SMR systems. Areas underlain by Tertiary aged sediments exhibited significantly higher mean DOC yields compared to their igneous counterparts, despite maintaining substantially lower aboveground carbon densities, suggesting the important influence of lithology. Finally, regression analyses between DOC yields and select watershed parameters revealed a negative and statistically significant relationship with maximum and mean gradient suggesting lower soil retention times may be linked to lower DOC yields. [ABSTRACT FROM AUTHOR]

Abstract: Laser-induced breakdown spectroscopy (LIBS) offers a means of rapidly distinguishing different geographic sources for a mineral because the LIBS plasma emission spectrum provides information on the chemical composition (i.e. geochemical fingerprint) of a geomaterial. An application of this approach with potentially significant commercial and political importance is the spectral fingerprinting of “conflict minerals” such as columbite–tantalite (“coltan”). Following a successful pilot study of a columbite–tantalite suite from North America, a more geographically diverse set of 57 samples from 37 locations around the world was analyzed using a commercially available LIBS system. The LIBS spectra were analyzed using advanced multivariate statistical signal processing techniques. Partial least squares discriminant analysis (PLSDA) resulted in a correct place-level geographic classification at success rates above 90%. The possible role of rare-earth elements (REEs) as a factor contributing to the high levels of sample discrimination was explored. These results provide additional evidence that LIBS has the potential to be utilized in the field as a real-time screening tool to discriminate between columbite–tantalite ores of different provenance. [Copyright &y& Elsevier]