Use Of Reflectance Spectroscopy Research Articles

Variability in Symbiont Chlorophyll of Hawaiian Corals from Field and Airborne Spectroscopy

Corals are habitat-forming organisms on tropical and sub-tropical reefs, often displaying diverse phenotypic behaviors that challenge field-based monitoring and assessment efforts. Symbiont chlorophyll (Chl) is a long-recognized indicator of intra- and inter-specific variation in coral’s response to environmental variability and stress, but the quantitative Chl assessment of corals at the reef scale continues to prove challenging. We integrated field, airborne, and laboratory techniques to test and apply the use of reflectance spectroscopy for in situ and reef-scale estimation of Chl a and Chl c2 concentrations in a shallow reef environment of Kāne‘ohe Bay, O‘ahu. High-fidelity spectral signatures (420–660 nm) derived from field and airborne spectroscopy quantified Chl a and Chl c2 concentrations with demonstrable precision and accuracy. Airborne imaging spectroscopy revealed a 10-fold range of Chl concentrations across the reef ecosystem. We discovered a differential pattern of Chl a and Chl c2 use in symbiont algae in coexisting corals indicative of a physiological response to decreasing light levels with increasing water depth. The depth-dependent ratio of Chl c2:a indicated the presence of two distinct light-driven habitats spanning just 5 m of water depth range. Our findings provide a pathway for further study of coral pigment responses to environmental conditions using field and high-resolution airborne imaging spectroscopy.

Disentangling the effects of phosphorus, nitrogen and species identity on the vegetation reflectance spectrum

AbstractQuestionsEffective and successful restoration of species‐rich semi‐natural grasslands requires knowledge of the soil nutrient status, including soil phosphorus availability. Plants are solid indicators of soil nutrient status, because their growth reflects nutrient availability integrated over a certain period. The use of reflectance spectroscopy to estimate vegetation nutrient content has the potential to offer a fast and efficient approach to provide information about soil nutrient availability for plants. Here, we investigated the effect and relative importance of vegetation phosphorus content compared with vegetation nitrogen content and species identity in explaining variation in vegetation reflectance.LocationPot experiment mimicking Western European grassland communities on a restoration trajectory.MethodsWe combined a pot experiment with a broad range of mesotrophic grassland species growing along a soil phosphorus gradient with a multivariate modelling approach. We measured vegetation spectra and vegetation phosphorus and nitrogen content in monocultures and mixtures.ResultsAlthough vegetation biochemistry explained a considerable part of the variation in vegetation reflectance, we found no pronounced absorption features for vegetation nitrogen and phosphorus content across the reflectance spectrum. The relatively large effect of species and community identity suggest that other drivers, for example vegetation architecture, overruled the effect of vegetation biochemistry on the reflectance spectrum. Our findings indicate that species detection and indirect case‐specific estimation of nutrients is possible, especially in structurally less‐complex canopies such as monospecific grass swards.ConclusionsDisentangling the specific drivers of variation in spectral reflectance is challenging. Many studies confound the effect of species identity on the vegetation reflectance spectrum with the effect of vegetation biochemistry. Here, we showed the importance of explicitly taking species identity into account. Gaining insight into light–vegetation interactions and the in‐depth integration of ecological theory in remote sensing are the way forward.

Near infrared spectroscopy to rapid assess the rubber tree clone and the influence of maturation and disease at the leaves

The rubber tree is a species of great economic importance due to its natural rubber, which is widely used in the tire industry due to its resistance and does not yet have a synthetic formula capable of completely replacing it. Near infrared spectroscopy (NIRS) is an emerging technique for soil and plant analysis. The aim of this study is to predict the Hevea rubber tree clones, detect and discriminate leaves at different stages of development (young or adult), as well as to discriminate healthy and affected adult leaves by South American Leaf Blight, through the spectroscopic technique of visible to infrared (Vis-NIR) combined with chemometrics. Using dried ground leaves samples, leaves from 14 rubber trees clones (H. brasiliensis) were evaluated, these leaves were collected in 3 tree stages young trees; adult or mature trees; and mature trees with symptoms of Microcyclus ulei (disease leaves). The near infrared (NIR) reflectance spectra were acquired using a spectrometer FOSS-NIRS (model DS2500). An average of 64 scans operating in a range between 400 and 2500 nm under spectral resolution of 0.5 nm were used for all the spectral acquisitions. With the use of reflectance spectroscopy in visible and near infrared, it was possible to efficiently discriminate the clones of the rubber tree, regardless of the use of spectra obtained from young leaves or from mature leaves. Which might enable studies with characterization of the genetic materials present in the germplasm banks and in situ. The technique also efficiently differentiated the young leaves from the mature leaves, as well as separating the healthy mature leaves from the diseased mature leaves. These results can contribute to the breeding and conservation programs of the species, obtaining fast results and without the use of chemical reagents.

Evaluation of a Micro-Electro Mechanical Systems Spectral Sensor for Soil Properties Estimation

Soil properties estimation with the use of reflectance spectroscopy has met major advances over the last decades. Their non-destructive nature and their high accuracy capacity enabled a breakthrough in the efficiency of performing soil analysis against conventional laboratory techniques. As the need for rapid, low cost, and accurate soil properties’ estimations increases, micro electro mechanical systems (MEMS) have been introduced and are becoming applicable for informed decision making in various domains. This work presents the assessment of a MEMS sensor (1750–2150 nm) in estimating clay and soil organic carbon (SOC) contents. The sensor was first tested under various experimental setups (different working distances and light intensities) through its similarity assessment (Spectral Angle Mapper) to the measurements of a spectroradiometer of the full 350–2500 nm range that was used as reference. MEMS performance was evaluated over spectra measured from 102 samples in laboratory conditions. Models’ calibrations were performed using random forest (RF) and partial least squares regression (PLSR). The results provide insights that MEMS could be employed for soil properties estimation, since the RF model demonstrated solid performance over both clay (R2 = 0.85) and SOC (R2 = 0.80). These findings pave the way for supporting daily agriculture applications and land related policies through the exploration of a wider set of soil properties.

P4 Recipe Sampling at Farmers' Market: Implications on Self-Reported Fruit and Vegetable Intake, Dermal Carotenoid Scores, and Intent to Prepare

<h3>Background</h3> Farmers' markets (FM) provide an opportunity for consumers to support local producers and promote fruit and vegetable (FV) intake. Plate It Up! Kentucky Proud (PIUKP) develops healthy recipes incorporating locally-produced specialty crops and educational resources that are then delivered by Extension professionals. In collaboration with local producers, Extension professionals often set up at the FM to provide PIUKP resources and recipe samples. As part of the PIUKP project, evaluation data is collected annually at FM throughout the state. <h3>Objective</h3> To evaluate the relationship between self-reported FV intake and dermal carotenoid scores in adult FM patrons and to assess the impact of PIUKP recipe sampling at the FM on intent to purchase and prepare locally-produced FV. <h3>Study Design, Setting, Participants</h3> Over a period of 3 summers, adult patrons (n = 751) at diverse FM's throughout the state were invited to sample a seasonally-appropriate PIUKP recipe and complete a short survey with questions about their typical FV intake, sampling experience, and FM purchasing habits. Dermal carotenoid levels were also evaluated in years 2 and 3 (n = 525) through reflection spectroscopy using the Veggie Meter. <h3>Measurable Outcome/Analysis</h3> Descriptive statistics are provided. Correlation analyses were used to evaluate the relationship between self-reported FV intake and dermal carotenoid scores. <h3>Results</h3> The study participants reported consuming an average of 2.22 ± 1.18 servings of fruits and 2.91 ± 1.48 servings of vegetables daily. Mean dermal carotenoid scores were 200.3 ± 87.6; a weak (r = 0.32) positive correlation was found between self-reported FV intake and dermal carotenoid scores. On a scale of 1 to 10 with 10 being "Contributes a Lot," participants indicated both recipe sampling (7.83 ± 2.23) and recipe cards (7.76 ± 2.34) contributed to their making a recipe using FV purchased at the FM. The majority (77.6%) of participants indicated they were very likely to purchase the FV highlighted in the sampled recipe. <h3>Conclusions</h3> Self-reported FV intake was weakly correlated with dermal carotenoid scores, indicating further research is needed to evaluate the use of reflection spectroscopy as a marker of FV intake. As well, providing samples of healthy recipes and recipe cards incorporating FV being sold at the FM contributed to the likelihood of purchase and later preparation of the recipe.

Prediction of Soil Texture Distributions by using PLSR and Reflectance Spectroscopy

The texture of soil i.e. Sand, Silt and Clay are the most important physical properties of soil for agricultural management. In the agricultural practices to increase the productivity of soil, moisture-holding capacity, aeration and to support the agronomic decisions the knowledge of soil texture is an essential task. For this purpose, the present research gives better results and fast acquisition of soil information with the use of Visible and Near Infrared (Vis- NIR) Diffuse Reflectance Spectroscopy. A total of 30 soil samples from two different locations from Aurangabad, Maharashtra, India were collected and analyzed for soil texture. To detect the soil texture the Vis-NIR DRS has shown levels of accurate results compared to the traditional laboratory method with less time, cost and effort. To measure the reflectance of soil the ASD FieldSpec4 Spectroradiometer (350-2500nm) was used. By the observation of captured spectra by using Spectroradiometer it showed that on the basis of different textural classes the soil samples could be spectrally separable. For database collection and pre-processing, we have used RS3 and ViewSpec Pro software respectively. The statistical analysis by using the combination of Principal Component Analysis (PCA) and Partial Least Square Regression method gives accurate results. To determine the texture of soil sample thirteen features were calculated. The main goal of this research was to determine the soil texture by using statistical methods and to test the performance of VNIR-SWIR reflectance spectroscopy by using the ASD FieldSpec4 Spectroradiometer for estimation of the texture of the soil. The results showed that R2 = 0.99 gives maximum accuracy for clay content and R2 = 0.988 for silt content and R2 = 0.989 for sand. The Root Mean Square Values (RMSE) for clay, silt, and sand are 0.02392, 0.02399 and 0.02289 respectively. With the use of reflectance spectroscopy and statistical analysis by using regression models we can determine the soil properties accurately in very less time.

Detecting symptoms of Phytophthora cinnamomi infection in Australian native vegetation using reflectance spectrometry: complex effects of water stress and species susceptibility

Diseases in natural and agricultural systems have been linked to species of the Oomycete genus Phytophthora, around the world. Direct detection of the pathogen requires sampling of soil or plant material, which can be expensive, difficult to obtain and error-prone. As an alternative, reflectance spectroscopy provides a potential indirect method for detecting symptoms of infection by P. cinnamomi. Here we evaluate the use of reflectance spectroscopy to detect physiological changes associated with infection in host plants using spectral indices designed to quantify changes in plant pigments (pigment indices), leaf water content (water indices) and fluorescence (fluorescence indices). Two grasses and two tree species with different susceptibilities to P. cinnamomi were inoculated and/or exposed to water stress in a glasshouse experiment. Inoculated plants were detected using pigment and fluorescence indices, which also had the capacity to separate inoculated plants from water stressed uninoculated plants. While inoculation may have caused an opposing spectral response to water stress in some indices, plants that were both water stressed and inoculated then demonstrated an intermediate response. Water stress was detected using the water indices in all four species, and spectroscopic changes associated with inoculation were often greater in the susceptible species. Our results indicate that reflectance spectroscopy at the leaf scale detects the effects of P. cinnamomi infection in native vegetation. Extending these results has the potential to improve early detection of disease in natural vegetation and avoiding manual sampling, thus improving management of the disease.

Newborn jaundice determination by reflectance spectroscopy using multiple polynomial regression, neural network, and support vector regression

Diffuse reflectance spectroscopy is a non-destructive method to obtain biochemical and physiological information by investigating the optical properties of skin. Transcutaneous bilirubin (TcB) measurement utilizes reflectance spectroscopy to determine the jaundice level in newborns. Although TcB measurement has some advantages over total serum bilirubin (TSB) measurement such as being non-invasive, noninfectious, painless, and instantaneous, the existing TcB devices cannot yet replace TSB devices due to the inaccuracy of measurements. In this paper, we propose the use of reflectance spectroscopy in conjunction with regression tools such as multiple polynomial regression (MPR), artificial neural network (ANN), and support vector regression (SVR) to predict the jaundice level. The proposed methods were tested on TcB measurement data obtained from 314 babies. TcB measurements were collected by two devices: a commercially available product, Draeger JM-103, and a prototype device on which we can implement the proposed algorithms. The results are encouraging towards increasing the clinical usage of transcutaneous bilirubinometers as all the three methods accurately predict the jaundice level with a correlation value between 0.932 and 0.943. The proposed use of ANN improves the non-invasive transcutaneous approach, with results converging to more accurate invasive serum bilirubin measurements by blood sampling.

Spectral Characteristics of Chemically Weathered Sandstones in the Yungang Grottoes, China

ABSTRACTMany of the sandstones at cultural heritage sites around the world are susceptible to chemical weathering, and long-term monitoring of the chemical weathering would be of great value for heritage conservation and would also provide reference data for environmental protection policies and projects. Reflectance spectroscopy is a potential tool for monitoring sandstone weathering due to its non-destructive characteristics. In this paper, we present the results of an investigation into the reflectance spectra of sandstones at the Yungang Grottoes, China, where the sandstones are variously fresh, calcite-dissolved, or argillitic-altered. We found several spectral absorptions, including those at 490, 675, 900, 1410, 1918, 2205, 2330, 2350, and 2380 nm. The absorptions at 490, 675, and 900 nm are related to hematite cement, while that at 2330 nm is associated with calcite cement. The absorptions at 1410, 2205, 2350, and 2380 nm are induced by the Al–OH vibration of kaolinite, and that at 1918 nm is related to crystal water. The calcite-dissolved sandstones have lower absorption intensities at 2330 nm than fresh sandstones, and the argillitic-altered sandstones have lower absorption intensities at 490, 675, and 900 nm than the fresh sandstones. In the 1st-derivative reflectance plots, the absorption peaks at ∼1400 nm shift towards shorter wavelengths with increasing kaolinite contents. The spectral features of the fresh, calcite-dissolved, and argillitic-altered sandstones are all different, and this means they can be distinguished spectroscopically, which demonstrates the usefulness of reflectance spectroscopy for the long-term monitoring of sandstone weathering in the Yungang Grottoes.

Reflectance spectroscopy: a novel approach to better understand and monitor the impact of air pollution on Mediterranean plants.

The Mediterranean basin can be considered a hot spot not only in terms of climate change (CC) but also for air quality. Assessing the impact of CC and air pollution on ecosystem functions is a challenging task, and adequate monitoring techniques are needed. This paper summarizes the present knowledge on the use of reflectance spectroscopy for the evaluation of the effects of air pollution on plants. First, the history of this technique is outlined. Next, we describe the vegetation reflectance spectrum, how it can be scaled from leaf to landscape levels, what information it contains, and how it can be exploited to understand plant and ecosystem functions. Finally, we review the literature concerning this topic, with special attention to Mediterranean air pollutants, showing the increasing interest in this technique. The ability of spectroscopy to detect the influence of air pollution on plant function of all major and minor Mediterranean pollutants has been evaluated, and ozone and its interaction with other gases (carbon dioxide, nitrogen oxides, and sulfur dioxide) have been the most studied. In the recent years, novel air pollutants, such as particulate matter, nitrogen deposition, and heavy metals, have drawn attention. Although various vegetation types have been studied, few of these species are representative of the Mediterranean environment. Thus, major emphasis should be placed on using vegetation spectroscopy for better understanding and monitoring the impact of air pollution on Mediterranean plants in the CC era.

Effect of Soil Use and Coverage on the Spectral Response of an Oxisol in the VIS-NIR-MIR Region

In this study, the spectral responses obtained from a Typic Red Hapludox (oxisol) were analyzed under different uses and occupations: Ficus elastica cultivation, Citrus + Arachis association cultivation, transitional crops, forest, Mangifera indica, Anacardium occidentale, Elaeis guineensis (18 years), Brachiaria decumbens, Brachiaria brizantha, and Musa × paradisiaca + Zea mays at the La Libertad Research Center in the department of Meta in Colombia (4°04′ North latitude, 73°30′ West longitude, 330 MAMSL). Sampling was performed with four random replicates of the horizon A and B to determine the contents of organic carbon (CO), pH, exchangeable acidity (Ac. I), cation exchange capacity (Cc), P, Ca, Mg, K, Na, sand, lime, and clay and spectral responses were obtained in the visible band (VIS), near infrared (NIR), and infrared (MIR) for each sample under laboratory conditions. A comparison was made between the obtained spectra, determining the main changes in soil properties due to their use and coverage. Variation of soil characteristics such as color, organic carbon content, presence of ferrous compounds, sand, silt, and clay content and mineralogy allow the identification of the main spectral changes of soils, demonstrating the importance of the use of reflectance spectroscopy as a tool of comparison and estimation between physical-chemical properties of the soils.

Use of Reflectance Spectroscopy as a Tool for Screening Viroid-Inoculated Oil Palm Seedlings

Reflectance spectroscopy was assessed as a new diagnostic tool for screening oil palm (Elaeis guineensis Jacq.) seedlings inoculated with Coconut cadang-cadang viroid (CCCVd). This study was aimed at non-destructive diagnosis of Orange Spotting (OS) disease of oil palm under glasshouse conditions. Leaf reflectance (in the detection range of 325-1075 nm) was acquired from oil palm seedlings with and without inoculation (control) of CCCVd. Spectral reflectance was measured at 15 and 30 days after inoculation using a non-imaging spectroradiometer, ASD FieldSpec® HandHeld™ 2. The red-edge region (680-780 nm) was investigated, and two spectral bands (i.e. 680 nm and 754 nm) were selected. Reflectance Sensitivity (RS) analysis was performed over these spectral bands. The far red band at 680 nm was found to be markedly sensitive to CCCVd infection while the spectral band at 754 nm was found to be insensitive. The 680 nm band gave an RS of 35.4% while the 754 nm band registered an RS of -5%. This study demonstrates the potential of screening CCCVd infection at an early stage (nursery establishment) non-destructively.

Hierarchical growth of TiO2 nanosheets on anodic ZnO nanowires for high efficiency dye-sensitized solar cells

We present a novel route to hierarchical core-shell structures consisting of an anodic ZnO nanowire core surrounded by a shell of TiO2 nanosheets ([email protected]). This material combines the beneficial properties of enhanced electron transport, provided by the nanowire core, with the high surface area and chemical stability of the TiO2 shell. Quasi-solid-state dye-sensitized solar cells (qssDSSCs) are prepared using different quantities of either the bare ZnO nanowires or the hierarchical nanowire structures and the effect on cell performance is examined. It is found that whilst the addition of the bare ZnO nanowires results in a decrease in cell performance, significant improvements can be achieved with the addition of small quantities of the hierarchical structures. Power conversion efficiencies of up to 7.5% are achieved under 1 Sun, AM 1.5 simulated sunlight, with a ∼30% increase compared to non-hierarchical mesoporous TiO2 films. A solid-state DSSC (ssDSSC) with a single component solid polymer also exhibits excellent efficiency of 7.2%. The improvement in cell performance is related to the improved light scattering, surface area and electron transport properties via the use of reflectance spectroscopy, BET surface area measurements and electrochemical impedance spectroscopy.

Assessing the use of reflectance spectroscopy in determining CsCl stress in the model species Arabidopsis thaliana

Reflectance spectroscopy is a rapid and non-destructive analytical technique that may be used for assessing plant stress, and has potential applications for use in remediation. Changes in reflectance such as that due to metal stress may occur before damage is visible, and existing studies have shown that metal stress does cause changes in plant reflectance. To further investigate the potential use of reflectance spectroscopy as a method for assessing metal stress in plants, an exploratory study was conducted in which Arabidopsis thaliana plants were treated twice weekly in a laboratory setting with varying levels (0, 0.5, or 5 mM (millimolar)) of caesium chloride (CsCl) solution, and reflectance spectra were collected every week for three weeks using an Analytical Spectral Devices FieldSpec Pro spectroradiometer with both a contact probe (CP) and a field of view (FOV) probe at 36.8 and 66.7 cm, respectively, above the plant. Plants were harvested each week after spectra collection for determination of relative water content and chlorophyll content. A visual assessment of the plants was also conducted using point observations on a uniform grid of 81 points. A mixed-effects model analysis was conducted for each vegetation index (VI) considered to determine the effects of length of treatment, treatment level, view with which spectra were acquired, and the interactions of these terms. Two-way analyses of variance (ANOVAs) were performed on the aforementioned endpoints (e.g. chlorophyll content) to determine the significance of the effects of treatment level and length of treatment. Multiple linear regression (MLR) was used to develop a predictive model for each endpoint, considering VI acquired at each view (CP, high FOV, and low FOV). Of the 14 VI considered, 8 were included in the MLR models. Contact probe readings and FOV readings differed significantly, but FOV measurements were generally consistent at each height.

Identificação dos padrões espectrais da alteração hidrotermal da Mina Uruguai, Caçapava do Sul (RS), utilizando espectros de reflectância experimental

Uma série de análises espectrais foi efetuada em amostras de rochas sedimentares eopaleozoicas afetadas por alteração hidrotermal associada às ocorrências de cobre na Mina Uruguai (Minas do Camaquã, RS). A base de dados contemplou espectros na faixa do visível e infravermelho próximo (350 a 2500 nm) obtidos através de leituras em um espectrorradiômetro portátil ASD FieldSpec-3 High-Resolution. A interpretação mineralógica das assinaturas espectrais foi efetuada com o apoio do software The Spectral Geologist (TSGTM Pro) que permitiu a discriminação das fases minerais presentes por comparação das feições de absorção no espectro analisado com feições similares de minerais de uma biblioteca espectral de referência. A partir da análise espectral das amostras da área de estudo, puderam ser identificados os seguintes minerais principais: caulinita, ilita, clorita, hematita e goetita. As assembleias minerais identificadas se mostraram consistentes com alteração hidrotermal sob condições epitermais de baixo enxofre descrita em estudos anteriores na região. Os resultados obtidos reforçaram o potencial de utilização da espectroscopia de reflectância em programas de exploração mineral, especialmente nas fases iniciais, mesmo em áreas com condições fisiográficas pouco favoráveis.

METHOD COMPARISON FOR ESTIMATION OF DISTRIBUTED PARAMETERS IN PERMITTIVITY MODELS USING REFLECTANCE

The use of reflectance spectroscopy is a current area of study for the non-invasive evaluation of complex materials such as ceramic matrix composites. In order to model the reflectance, one must specify a model for the complex permittivity. In this work we compare two methods for modeling the complex permittivity of a heterogenous material. In one approach, we impose a probability distribution on a subset of the dielectric parameters. This approach leads to an infinite dimensional optimization problem over the space of probability measures. We approximate this space with a finite dimensional space by using either a Dirac approximation method or a linear spline approximation method. The second approach is to assume a number of oscillators in the permittivity model, and then use a convolution with a normal distribution. We compare both of these approaches on simulated data sets as well as data obtained from inorganic glasses. Each of these methods are able to fit the data well, yet the ease in interpreting the estimation results of imposing a probability distribution on parameters, as well as the tight mathematical results [2, 7] guaranteeing convergence under the Prohorov metric, lead us to favor the first approach.

Studies on the reflectance spectral features of saline soil along the middle reaches of Tarim River: a case study in Xinjiang Autonomous Region, China

There has been growing interest in the use of reflectance spectroscopy as a rapid and inexpensive tool for soil characterization. In this study, 53 soil samples were collected from the oasis in the Weigan and Kuqa River delta along the middle reaches of Tarim River to investigate the level of soil chemical components in relation to soil spectral. An approach combining spectral technology and multi-variant statistical analysis was used to determine the reflectance spectral features of saline soil. The spectral data was first pretreated to remove noises and absorption bands from water, which eliminated influence from instrument errors and other external background factors. Several spectral absorption features were calculated for several saline soil samples to confirm that soil at the same salinity level had similar absorption spectral properties. Secondly, a correlation relationship between reflectance spectra and salinity factors was estimated by bivariate correlation method. Fourteen salinity factors including eight major ions and soil electrical conductivity (EC), soil salt content (SSC), pH, and total dissolved solid (TDS) in the saline soil were evaluated. Datasets of the salinity factors that correlated significantly with field data measurements of reflectance rate and the corresponding spectrum data were used to construct quantitative regression models. According to the multiple linear regression analysis, SSC, SO42−, TDS, and EC had a correlation coefficient at 0.746, 0.908, 0.798, and 0.933 with the raw spectral data, respectively, which confirmed strong correlation between salinity factors and soil reflectance spectrum. Findings from this study will have significant impact on characterization of spectral features of saline soil in oasis in arid land.

A Spectroscopic Approach to Assess Heavy Metals Contents of the Mine Waste of Jalta and Bougrine in the North of Tunisia

Near InfraRed Spectroscopy (NIRS) has become an extremely important analytical technique in recent years and been applied in various geoscience areas such as mineral exploration and environmental studies. It is used for studying the physico-chemical properties of earth materials by enabling the interpretation of mineral composition and the study of its variability based on the diagnostic of spectral features. In this research, the application of laboratory reflectance spectroscopy in assessing heavy metals pollution is investigated. The potential use of reflectance spectroscopy in detecting Fe-related and clay minerals as well as the quantitative characterization of pollutants is studied for the mine waste of Jalta and Bougrine in the North of Tunisia. Mining activities of lead/Zn, have led to extensive pollution. The analysis of geochemical results outlined the level and spatial pattern of pollutants concentration. Results of the study showed that a relationship exists between reflectance spectra and geochemical measures of pollutants. The Spectral interpretation of Fe-related minerals and clay minerals showed that they are related to the pollutants and can be used as indirect spectral indicators of the pollution. The Fe-minerals include: jarosite, goethite, hematite/goethite, and hematite; clay minerals and feature-less (aspectral) materials. A direct quantitative relationship between pollutants and spectral parameters shows that Pb-Zn-Mn are the best correlated with a ratio of 610/500 nm range while Ni-Cr have a best correlation with a slope around 980 nm. Outputs from Partial Least Square Regression (PLSR) confirmed these relationships and also indicated that spectral parameters and reflectance values within 400 - 2500 nm range can better predict the contamination for Mn, Pb and Zn than for Ni and Cr but not for Fe, Cu, Cd, EC and pH.

Reflectance Spectroscopy as a Monitor of the Thermal-Decomposition Products of Europium Trichloride Hexahydrate

ABSTRACT The thermal-decomposition products of EuCl3 · 6H2O can be monitored through the use of ultraviolet/visible reflectance spectroscopy. The use of reflectance spectroscopy proved complimentary to other spectroscopic methods, combining to give a more complete representation of the decomposition products. Using variations in spectral features of the reflectance spectra, the penta- and tetrahydrate decomposition products were identified, along with the tri- and di-monohydrate compounds that were identified by luminescence spectroscopy. The observed intermediates and their corresponding decomposition temperatures can be compared to those obtained by other methods. Structural and environmental inferences as indicated by the reflectance spectra are discussed.

Reflectance spectroscopy: a new approach for reconstructing penguin population size from Antarctic ornithogenic sediments

Reflectance spectroscopy has several advantages compared to traditional chemical methods in paleolimnology. It requires little cost, involves minimal or no sample preparation and is rapid. There has, however, been limited use of reflectance spectroscopy in polar paleolimnological studies. This paper explores the application of reflectance spectroscopy to reconstruct historical changes in penguin population size in the maritime Antarctic. Two ornithogenic sediment cores on Ardley Island, Antarctica were analyzed. Penguin droppings and weathered soils were analyzed as reference materials. Principal component analysis and linear mixing modeling were performed on the spectral data to estimate the proportion of penguin guano in the sediments and these values were used to infer historical penguin population numbers. Historical penguin population size versus time, reconstructed from reflectance spectra, and population numbers inferred from previous geochemical analysis of bio-elements, were quite similar. Our results illustrate the feasibility of rapidly inferring historical changes in penguin population size using reflectance spectroscopy on Antarctic ornithogenic sediments. Our findings suggest that this technique has potential for reconstructing past population numbers of other seabirds and mammals using lake sediments influenced by animal excrement.