Rivers act as temporary sinks of microplastics and a key medium allowing microplastics to enter the ocean. In this study, microplastics pollution in river shore sediment of the Indian Himalaya, ...including the Brahmaputra River and the Indus River was discussed. Sampling campaigns were performed in years 2018 and 2019. Sample pretreatment was performed using Na2WO4·2H2O for density separation and H2O2 for oxidation of organic material. Microplastics analysis was performed by using FTIR microscope. The smaller size of microplastics 20–150 μm were more abundant (531–3485 MP/kg in the Brahmaputra River and 525–1752 MP/kg in the Indus River) than microplastics in size range between 150 μm and 5 mm (20–240 MP/kg in the Brahmaputra River and 60–340 MP/kg in the Indus River). Microplastics were found in sediments of all sampling sites. Fragmented, secondary microplastics were dominant in the river shore sediment of the Indian Himalaya. This study contributes towards filling research gap of microplastics in India's freshwater source and highlights the importance of in-depth complete studies of microplastics in the rivers that act as pathways and sinks for microplastics.
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•Microplastics in shore sediment of Brahmaputra River and Indus River were studied.•Fragmented, 20 ̶150 μm size microplastics dominated the samples.•Polypropylene and polyethylene were most abundantly found.•Anthropogenic activities and hydrological factors impacted microplastics distribution.•Surface morphology of microplastics showed mechanical and oxidative weathering.
Photogrammetric methods enable the construction of 3D SEM models from 2D images. Most software for this purpose is designed for photographic images. The software tries to minimize modelling error but ...some uncertainty usually remains in the model. In such approaches no ground truth measurement for microscopic objects exists for comparison with the finished model. In the proposed method, a textured model surface is compared to the SEM images to map the error locations on the model. The method is illustrated using two datasets.
•Feasible novel quality measure.•Insight’s uncertainty of textured sub images.•3D modelling of SEM images.•Photogrammetry software as modelling tool.
Pansharpening constitutes a category of data fusion techniques designed to enhance the spatial resolution of multispectral (MS) images by integrating spatial details from a high-resolution ...panchromatic (PAN) image. This process combines the high-spectral data of MS images with the rich spatial information of the PAN image, resulting in a pansharpened output ideal for more effective image analysis, such as object detection and environmental monitoring. Traditionally developed for satellite data, our paper introduces a novel pansharpening approach customized for the fusion of Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectrometry (EDS) data. The proposed method, grounded in Partial Least Squares regression with Discriminant Analysis (PLS-DA), significantly boosts the spatial resolution of EDS data while preserving spectral details. A key feature of this approach involves partitioning the PAN image into intensity bins and dynamically adapting this division in cases of overlapping compounds with similar average atomic numbers. We evaluate the method's effectiveness using in-house EDS images obtained from both even and uneven sample surfaces. Comparative analysis against existing benchmarks and state-of-the-art pansharpening techniques demonstrates superior performance in both spectral and spatial quality indicators for our method.
Membrane fouling, i.e. accumulation of unwanted material on the surface of the membrane is a significant problem in filtration processes since it commonly degrades membrane performance and increases ...operating costs. Therefore, the advantages of early stage monitoring and control of fouling are widely recognized. In this work, the potential of using Raman spectroscopy coupled to chemometrics in order to quantify degree of membrane fouling in real-time was investigated. The Raman data set collected from adsorption experiments with varying pHs and concentrations of model compound vanillin was used to develop a predictive model based on principal component analysis (PCA) for the quantification of the vanillin adsorbed on the membrane. The correspondence between the predicted concentrations based on the PCA model and actual measured concentrations of adsorbed vanillin was moderately good. The model developed was successful in monitoring both adsorption and desorption processes. Furthermore, the model was able to detect abnormally proceeding experiment based on differentiating PCA score and loading values. The results indicated that the presented approach of using Raman spectroscopy combined with a PCA model has potential for use in monitoring and control of fouling and cleaning in membrane processes.
As an important component of organic carbon (OC), brown carbon (BrC) plays a significant role in radiative forcing in the atmosphere. Water-insoluble OC (WIOC) generally has higher light absorption ...ability than water-soluble OC (WSOC). The mass absorption cross-section (MAC) of WIOC is normally investigated by dissolving OC in methanol. However, all the current methods have shortcomings due to neglecting the methanol insoluble particulate carbon that is detached from the filter and suspended in methanol extracts, which results in MAC uncertainties of the methanol-soluble BrC and its climate warming estimation. In this study, by investigating typical biomass combustion sourced aerosols from the Tibetan Plateau and ambient aerosols from rural and urban areas in China, we evaluated the light absorption of extractable OC fraction for the existing methods. Moreover, a new method was developed to overcome the methanol insoluble particulate carbon detachment problem to achieve more reliable MAC values. We found that OC can be dissolved in methanol in a short time (e.g., 1 h) and ultrasonic treatment and long-term soaking do not significantly increase the extractable OC fraction. Additionally, we proved that methanol insoluble particulate carbon detachment in methanol does exist in previous methods, causing overestimation of the BrC mass extracted by methanol and thus the underestimation of MAC values. We therefore recommend the newly developed extraction method in this study to be utilized in future related studies to quantitatively obtain the light absorption property of methanol-soluble BrC.
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•Light absorption of water-insoluble BrC is studied by extracting OC with methanol.•Uncertainties of previous methods to extract methanol-soluble BrC are discussed.•A new extraction method is developed to obtain reliable MAC of methanol-soluble BrC.
A new method is developed to overcome the particulate carbon detachment problem during the extraction of methanol-soluble BrC, and thus the reliable MAC is obtained.
The advent of portable Fourier-Transform Infrared (FTIR) and Raman spectrometers has revolutionized analysis capabilities, presenting the possibility of on-site contaminant identification without the ...need for specialized laboratory settings. Compared to laboratory instrumentation, portable spectroscopy is more prone to noise, and appropriate spectral processing procedures need to be established. This paper introduces a comprehensive methodology that integrates acquisition techniques, spectral analysis, and mathematical tools necessary for utilizing handheld spectrometers to diagnose plant contamination. It focuses on determining the efficacy of handheld FTIR, Raman spectroscopy, and digital imaging for detecting contaminants in two food plants, Basil (Ocimum basilicum) and Mint (Mentha). The study examines the impact of three pollutants: iron (II) sulphate (FeSO4), zinc (II) sulphate (ZnSO4), and copper (II) sulphate (CuSO4), on these plants, but also the necessary amount of measurements to spot the pollutants' effects. Measurements were conducted at the start, after 24 hours, and after 48 hours of exposure, on both fresh and dried plant leaves, as well as in solution. Spectral effects of each of the pollutants were identified with the use of multivariate statistical process control techniques. With the help of the developed methodologies, researchers can identify in-situ contaminant effects, exposure times and run diagnostics directly on the leaf both in alive and dried plants.
•Handheld instrumentation gives noisier spectra than laboratory instrumentation.•Appropriate mathematical handling makes handheld data usable.•Colorimetric studies can be utilized for plant control.•Cu2+, Zn2+ and Fe2+ contaminants are detected in plants with handheld instrumentation.
Electric conductivity (EC), concentrations of major ions, total organic carbon, total nitrogen, optical density at 254 nm (D254) and fluorescence intensities characterizing protein-like and ...humic-like fluorescence were determined in water samples of urban river Okhta. Principal component analysis for values of measured parameters found 5-6 principal components (PC), three of them were explained by loadings values. PC1 was responsible for the most part of variance and reflected wastewater pollution with dissolved salts and organic matter. PC 2 was supposed to reflect organic matter of natural origin from the unpolluted stream water. Combination of EC and fluorimetric parameters of water were suggested for pollution monitoring in river waters.
Efficient overall processing of wood biomass still lacks suitable concepts for analytical strategies. The traditional strategy is based on compound-targeted analytical tools, which, however, tend to ...expand the range of required methods for each unit process and restrict the amount of results gained from process monitoring. Especially, development of heterogeneous bioprocess streams would benefit from expanding the range of results gained from applied analytical methods. Therefore, this study was executed in order to demonstrate a novel strategy for the analytical methods to meet the requirements of suitable and efficient process monitoring. The advantages of a novel strategy for interpretation of chemical analysis results by exploiting capillary zone electrophoresis (CZE) with ultraviolet (UV) detection at two complementary wavelengths are presented. Electropherograms of wood-based bioprocess samples were studied as examples with a heterogeneous composition of carbohydrates. Results show that a fairly simple CZE method has the advantage of providing a thorough characterisation of the sample profiles in the preliminary identification of unknown compounds in a heterogeneous wood-based sample.
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