The widespread presence of microplastics (MPs) in the air and their potential impact on human health underscore the pressing need to develop robust methods for quantifying their presence, ...particularly in the breathable fraction (<5 μm). In this study, Raman micro-spectroscopy (μRaman) was employed to assess the concentration of indoor airborne MPs >1 μm in four indoor environments (a meeting room, a workshop, and two apartments) under different levels of human activity. The indoor airborne MP concentration spanned between 58 and 684 MPs per cubic meter (MP m−3) (median 212 MP m−3, MPs/non-plastic ratio 0–1.6%), depending not only on the type and level of human activity, but also on the surface area and air circulation of the investigated locations. Additionally, we assessed in the same environments the filtration performance of a type IIR surgical facemask, which could overall retain 85.4 ± 3.9% of the MPs. We furthermore estimated a human MP intake from indoor air of 3415 ± 2881 MPs day−1 (mostly poly-amide MPs), which could be decreased to 283 ± 317 MPs day−1 using the surgical facemask. However, for the breathable fraction of MPs (1–5 μm), the efficiency of the surgical mask was reduced to 57.6%.
Display omitted
•Airborne MPs >1 μm were quantified in four indoor locations with μRaman.•Effect of human activity and surgical facemask was investigated.•MP concentration was 58–684 MP m−3 (median 212 MP m−3).•Only 57.6% of the 1–5 μm MP was filtered out by the surgical facemask.•Estimated MP intake: 3415 MPs day−1 (283 MPs day−1 with facemask).
The drinking water of a German city was investigated for microplastics. Random samples were taken from three house connections, one transfer station, and five consumption taps in an educational ...institution, an apartment, a single-family house, a residential building, and a commercial enterprise. The sample volumes ranged from 0.25–1.3 m3. A stainless-steel membrane served as a sampling filter. HCl was used for the acidic digestion of the inorganic precipitates. Raman micro spectroscopy was used for the analysis of microplastic particles. The detection limit was 10 μm. Particles and fibers ≥100 μm were measured on 100% of the filter area, while particles and fibers <100 μm were measured on 50% of the filter area. The analytical procedure was validated by determining recovery rates and analyses of blanks. In addition to microplastics, pigmented particles and fibers were also analyzed. Neither microplastic particles and fibers nor pigmented particles and fibers were detected at house connections and the transfer station. No microplastics were detected in any sample at consumption taps. At one tap, 113 ± 83 copper phthalocyanine particles m−3 were detected.
Display omitted
•No microplastics but pigmented particles were detected in the drinking water.•Drinking water samples were prepared for Raman spectroscopy by acidic digestion.•The resistance of most polymers to HCl (1 mol L−1) for 48 h at 50 °C was proved.•The recovery rate of particles is 53 ± 14% (22–27 μm) and 89 ± 28% (45–53 μm).•0.65 ± 0.54 microplastics per blank show an effective mitigation of contamination.
Purpose
The purpose of this work is to develop a new approach for high spatial resolution dosimetry based on Raman micro‐spectroscopy scanning of radiochromic film (RCF). The goal is to generate dose ...calibration curves over an extended dose range from 0 to 50 Gy and with improved sensitivity to low (<2 Gy) doses, in addition to evaluating the uncertainties in dose estimation associated with the calibration curves.
Methods
Samples of RCF (EBT3) were irradiated at a broad dose range of 0.03–50 Gy using an Elekta Synergy clinical linear accelerator. Raman spectra were acquired with a custom‐built Raman micro‐spectroscopy setup involving a 500 mW, multimode 785 nm laser focused to a lateral spot diameter of 30 µm on the RCF. The depth of focus of 34 µm enabled the concurrent collection of Raman spectra from the RCF active layer and the polyester laminate. The preprocessed Raman spectra were normalized to the intensity of the 1614 cm−1 Raman peak from the polyester laminate that was unaltered by radiation. The mean intensities and the corresponding standard deviation of the active layer Raman peaks at 696, 1445, and 2060 cm−1 were determined for the 150 × 100 µm2 scan area per dose value. This was used to generate three calibration curves that enabled the conversion of the measured Raman intensity to dose values. The experimental, fitting, and total dose uncertainty was determined across the entire dose range for the dosimetry system of Raman micro‐spectroscopy and RCF.
Results
In contrast to previous work that investigated the Raman response of RCFs using different methods, high resolution in the dose response of the RCF, even down to 0.03 Gy, was obtained in this study. The dynamic range of the calibration curves based on all three Raman peaks in the RCF extended up to 50 Gy with no saturation. At a spatial resolution of 30 × 30 µm2, the total uncertainty in estimating dose in the 0.5–50 Gy dose range was 6–9% for all three Raman calibration curves. This consisted of the experimental uncertainty of 5–8%, and the fitting uncertainty of 2.5–4.5%. The main contribution to the experimental uncertainty was determined to be from the scan area inhomogeneity which can be readily reduced in future experiments. The fitting uncertainty could be reduced by performing Raman measurements on RCF samples at further intermediate dose values in the high and low dose range.
Conclusions
The high spatial resolution experimental dosimetry technique based on Raman micro‐spectroscopy and RCF presented here, could become potentially useful for applications in microdosimetry to produce meaningful dose estimates in cellular targets, as well as for applications based on small field dosimetry that involve high dose gradients.
Display omitted
•A rare wood ash glass tessera from Malbork Madonna was studied in detail.•It was found to be original mediaeval, from the area north of Alps, coloured by Co.•Opacification was ...achieved by Ca-phosphate grains, a Mediterranean technology.•Two phases detected in tessera for the first time: leucite and pseudowollastonite.•Pseudowollastonite indicates production temperature above ca. 1125 °C.
While the natron and plant ash glass tesserae may be found on places of importance across the former Roman and Byzantine empires, wood ash glass tesserae are scarce. This is the first time a wood ash glass tessera is studied in detail. It was part of a magnificent 8-metres tall statue of Madonna in Malbork, Poland, created at the end of the 14th century and destroyed at the end of World War Two. It was found to be coloured by cobalt with possible impact of copper, and opacified by Ca-phosphate. Processes previously described in sodium-rich glasses were observed also in the studied potassium-rich wood ash glass tessera, such as diffusion of the respective alkali metal into the Ca-phosphate grains. The elemental composition of the tessera indicates that it is original – mediaeval, from the area north of Alps. Two phases were identified for the first time, to authors’ best knowledge, in any glass tessera – leucite (tetragonal KAlSi2O6) and pseudowollastonite (monoclinic CaSiO3). As pseudowollastonite is a high-temperature phase, it may serve as an indicator of production temperature, which was further supported by the study of polymerisation index of model glasses. This study contributes to the knowledge of old technologies and showed that the know-how for opacification was imported from the Mediterranean, while the raw materials employed for the base glass preparation were from the area north of Alps.
Microplastic (MPs) pollution in the aquatic and terrestrial environments has caught many attentions in the scientific literatures. Currently, no information is available about MPs pollution in ...Caspian Sea, the largest lake in the world. This study indicates the first report on the MPs pollution in the sediments of the southern Caspian coastal zones, northern Iran. Density separation method was conducted on 17 surficial sediments. The combination of observation techniques including SEM-EDS analysis, polarized light microscopy and Raman micro-spectroscopy were used to identify MPs. The abundance and size of microplastics in the samples ranged between 25 and 330 items/kg and 250–500 μm, respectively. Fibers constituted the most common MPs shape and polystyrene (PS) and polyethylene (PE) were major polymer types in the samples. The distribution of MPs in the study area reflected a patchy and irregular spatial pattern implying that the higher MPs concentration are near mouth of permanent rivers and in the regions with higher level of the fishing and tourism activities. The results showed the wide occurrence of MPs in the sediments of the world’s largest lake which extend the knowledge on MPs pollution in the marine system. We also recommend further research on microplastics in different compartments of Caspian Sea to inform policy discussions and the development of appropriate management responses.
Display omitted
•Microplastics abundance were studied for the first time in the Caspian Sea.•Microplastic levels were comparable with those found in worldwide marine sediments.•Polystyrene and Polyethylene were the main polymer types.•Fishing and tourism might be the main sources of MPs in the coasts.
Apatite-group phosphates are nearly ubiquitous in carbonatites, but our understanding of these minerals is inadequate, particularly in the areas of element partitioning and petrogenetic ...interpretation of their compositional variation among spatially associated rocks and within individual crystals. In the present work, the mode of occurrence, and major- and trace-element chemistry of apatite (sensu lato) from calcite and dolomite carbonatites, their associated cumulate rocks (including phoscorites) and hydrothermal parageneses were studied using a set of 80 samples from 50 localities worldwide. The majority of this set represents material for which no analytical data are available in the literature. Electron-microprobe and laser-ablation mass-spectrometry data (~600 and 400 analyses, respectively), accompanied by back-scattered-electron and cathodoluminescence images and Raman spectra, were used to identify the key compositional characteristics and zoning patterns of carbonatitic apatite. These data are placed in the context of phosphorus geochemistry in carbonatitic systems and carbonatite evolution, and compared to the models proposed by previous workers. The documented variations in apatite morphology and zoning represent a detailed record of a wide range of evolutionary processes, both magmatic and fluid-driven. The majority of igneous apatite from the examined rocks is Cl-poor fluorapatite or F-rich hydroxylapatite (≥0.3apfu F) with 0.2–2.7wt.% SrO, 0–4.5wt.% LREE2O3, 0–0.8wt.% Na2O, and low levels of other cations accommodated in the Ca site (up to 1000ppm Mn, 2300ppm Fe, 200ppm Ba, 150ppm Pb, 700ppm Th and 150ppm U), none of which show meaningful correlation with the host-rock type. Silicate, (SO4)2− and (VO4)3− anions, substituting for (PO4)3−, tend to occur in greater abundance in crystals from calcite carbonatites (up to 4.2wt.% SiO2, 1.5wt.% SO3 and 660ppm V). Although (CO3)2− groups are very likely present in some samples, Raman micro-spectroscopy proved inconclusive for apatites with small P-site deficiencies and other substituent elements in this site. Indicator REE ratios sensitive to redox conditions (δCe, δEu) and hydrothermal overprint (δY) form a fairly tight cluster of values (0.8–1.3, 0.8–1.1 and 0.6–0.9, respectively) and may be used in combination with trace-element abundances for the development of geochemical exploration tools. Hydrothermal apatite forms in carbonatites as the product of replacement of primary apatite, or is deposited in fractures and interstices as euhedral crystals and aggregates associated with typical late-stage minerals (e.g., quartz and chlorite). Hydrothermal apatite is typically depleted in Sr, REE, Mn and Th, but enriched in F (up to 4.8wt.%) relative to its igneous precursor, and also differs from the latter in at least some of key REE ratios e.g., shows (La/Yb)cn≤25, or a negative Ce anomaly. The only significant exception is Sr(± REE,Na)-rich replacement zones and overgrowths on igneous apatite from some dolomite(-bearing) carbonatites. Their crystallization conditions and source fluid appear to be very different from the more common Sr-REE-depleted variety. Based on the new evidence presented in this work, trace-element partitioning between apatite and carbonatitic magmas, phosphate solubility in these magmas, and compositional variation of apatite-group minerals from spatially associated carbonatitic rocks are critically re-evaluated.
•Hydrothermal and igneous apatites in carbonatites are compositionally distinct.•Trace-element ratios in carbonatitic apatite can be used to develop geochemical exploration tools.•REE is compatible with respect to apatite and follows two-site partitioning.•Compositional variation and zoning of carbonatitic apatite are a sensitive record of its history.
Rapid, sensitive and label‐free methods to probe bacterial growth irrespective of the culture conditions can shed light on the mechanisms by which bacteria adapt to different environmental stimuli. ...Raman spectroscopy can rapidly and continuously monitor the growth of bacteria under varied conditions. In this study, the growth of Escherichia coli in Luria broth (nutrient rich conditions) and minimal media with either glucose or glycerol as carbon source (nutrient limiting conditions) is profiled using Raman spectroscopy. Moreover, the study also gives insights into the altered bacterial biochemistry upon exposure to low‐ (25°C) and high‐temperature (45°C) stress. Raman spectral measurement was performed on bulk bacteria cultured under laboratory conditions. A detailed analysis of the spectra as a function of bacterial growth reveals changes in Raman band intensities/area of biomolecules such as DNA, proteins and lipids. We also report five novel ratiometric markers (I830/I810, I1126/I1100, I1340/I1440, I1207/I1240 and I1580/I1440) that can identify the phase of growth, independent of the culture condition. Unsupervised multivariate methods like Principal Component Analysis also corroborate the aforementioned markers of growth. Altogether, our findings highlight the potential of Raman spectroscopy in yielding universal biochemical signatures that may be indicative of stress and aging in a growth milieu.
Escherichia coli has been grown in different conditions and corresponding biochemical signatures in each metabolic stage have been obtained using Raman micro‐spectroscopy. A detailed spectral analysis has been performed to identify minuscule spectral changes depending on culture condition. A library of such Raman markers at various growth conditions can be a great tool for understanding bacterial mechanism for adapting adverse conditions.
The quantitative determination of topically applied substances in the skin is severely limited and represents a challenging task. The porcine skin ex vivo was topically treated with a gel containing ...caffeine (CF) and propylene glycol (PG), and depth‐resolved Raman spectra were recorded with two confocal Raman microscopes. We applied a novel tailored multivariate curve resolution‐alternating least squares method to the selected spectral regions (512–604 and 778–1148 cm−1) of gel‐treated skin and quantitatively determined the concentrations of CF and PG in the stratum corneum (SC). The highest concentration of CF (181 mg/cm3) was found at the surface, while PG (384 mg/cm3) was found at 10% SC depth, indicating the formation of a reservoir at the superficial SC. The concentrations of CF and PG decreased monotonically and reached the detection limit at ≈60% and ≈80% SC depth, respectively, indicating that neither permeate the SC.
The novel tailored multivariate curve resolution‐alternating least squares method is used to quantitatively determine the penetration profiles of caffeine (CF) and propylene glycol (PG) applied to the skin in a mixture. PG creates a reservoir at the superficial stratum corneum (SC) depth. The concentrations of CF and PG decrease monotonically and reach the detection limit at a depth of 60% SC depth (≈9 μm) and 80% SC depth (≈12 μm), respectively, indicating that neither permeate the SC.
Microplastics (MPs) are present across the global ocean and can be encountered by many species, including zooplankton. Although they fall within the size range of zooplankton prey, there are few ...studies on MPs ingestion carried out in situ. In this study, we analyzed MPs ingestion during two seasons (rainy and dry) of organisms from 5 taxonomic groups of zooplankton from two bays of the Mexican central Pacific: Manzanillo and Navidad. In total, 2643 individuals were analyzed, and of those 23 individuals contained MPs. The ingestion rate by taxonomic group was 1 MP/36 copepods (0.02), 1 MP/30 decapods–mysis (0.03), 1 MP/29 decapods–megalopa (0.03), and 1 MP/200 fish larvae (0.005). No plastics were found in chaetognaths, amphipods, or decapods–zoea. The average length of the ingested particles was 468.1 ± 113.8 μm, with a minimum of 15.6 and a maximum of 647.6 μm. All MPs >300 μm were fibers, with diameters <50 μm. Fragments were the most abundant MPs (54.2%), followed by fibers (34.2%) and spheres (11.4%). Statistical analyses showed no significant differences (p > 0.05) between the bays or seasons. Using RAMAN spectroscopy, it was possible to identify 6 different types of polymers, with poly (ethylene:propylene) being the most abundant (42.8%). This polymer is commonly used to manufacture plastic bags, ropes and fishing nets. The results confirm that certain zooplankton groups are consuming MPs and suggest that omnivorous species are more likely to ingest MPs, possibly due to their capacity for foraging flexibility and opportunistic feeding strategies. However, the ingestion of MPs cannot be attributed to a single factor; it is necessary to consider variables such as the sampling area, feeding strategy, size, and seasonality to understand the dynamics of MPs ingestion by zooplankton groups.
Display omitted
•Zooplankton organisms are consuming microplastics in the Central Mexican Pacific.•Feeding strategy and life stages can increase the consumption of microplastics.•In situ studies are vital to understand microplastic ingestion by zooplankton.•Variables such as sampling area and seasonal dynamics should be considered.•Confirmation of plastic particles through infrared spectroscopy is essential.
PDF
