Biochemical and biophysical drivers of the hydrogen isotopic composition of carbohydrates and acetogenic lipids.

The hydrogen isotopic composition (δ2H) of plant compounds is increasingly used as a hydroclimatic proxy; however, the interpretation of δ2H values is hampered by potential coeffecting biochemical and biophysical processes. Here, we studied δ2H values of water and carbohydrates in leaves and roots, and of leaf n-alkanes, in two distinct tobacco (Nicotiana sylvestris) experiments. Large differences in plant performance and biochemistry resulted from (a) soil fertilization with varying nitrogen (N) species ratios and (b) knockout-induced starch deficiency. We observed a strong 2H-enrichment in sugars and starch with a decreasing performance induced by increasing NO3-/NH4+ ratios and starch deficiency, as well as from leaves to roots. However, δ2H values of cellulose and n-alkanes were less affected. We show that relative concentrations of sugars and starch, interlinked with leaf gas exchange, shape δ2H values of carbohydrates. We thus provide insights into drivers of hydrogen isotopic composition of plant compounds and into the mechanistic modeling of plant cellulose δ2H values.

Distribution, sources and ecological risks of PAHs and n-alkanes in water and sediments of typically polluted estuaries: Insights from the Xiaoqing River.

Seasonal water and sediment samples were collected from the Xiaoqing River estuary and the neighboring sea to study the spatial and temporal distributions, sources and ecological risks of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes. The results showed significant spatial and temporal differences in the concentrations of PAHs and n-alkanes under the influence of precipitation, temperature, and human activities. The concentrations of PAHs in water were lower in the wet season than in the dry season, and those in sediments were higher in the wet season than in the dry season. The concentrations of n-alkanes were higher in the rainy season than in the dry season for both water and sediments. The spatial distributions of PAHs and n-alkanes were estuarine > offshore. The concentration ranges of ∑PAHs in water and sediments were 230.66-599.86 ng/L and 84.51-5548.62 ng/g, respectively, in the wet season and 192.46-8649.55 ng/L and 23.39-1208.92 ng/g, respectively, in the dry season. The proportion of three-ring PAHs in water (57.03% and 78.27% in the wet and dry seasons, respectively) was high, followed by two-ring PAHs (27.31% and 13.59% in the wet and dry seasons, respectively). The proportion of four-ring PAHs was higher in sediments (24.79% and 32.20% in the wet and dry seasons, respectively). The ecological risk of PAHs assessed using the toxicity equivalent quotient and risk quotient was at moderate to moderately high risk levels. The high concentration of n-alkane fraction C16 (611.65-75594.58 ng/L) in the water is indicative of petroleum or other fossil fuel inputs. The main peaks of n-alkanes in river sediments were C27, C29 and C31, indicating higher inputs of plant sources. The sediments in the estuary showed dominance of both short-chain C16 and long-chain C25-C31, indicating a combined input of higher plants and petroleum. The diagnostic ratios of PAHs and n-alkanes indicated that their sources were mainly oil/coal/biomass combustion and petroleum spills attributed to frequent vehicular, vessel and mariculture activities. Given the potential ecological risks of PAHs and n-alkanes in water and sediments, future studies should focus on their bioaccumulation and biotoxicity.

A microchip gas chromatography column assembly with a 3D metal printing micro column oven and a flexible stainless-steel column.

In this work, a microchip gas chromatography (GC) column assembly utilizing a three-dimensional (3D) printed micro oven and a flexible stainless steel capillary column was developed. The assembly's performance and separation capabilities were characterized. The key components include a 3D printed aluminum plate (7.50 × 7.50 × 0.16 cm) with a 3-meter-long circular spiral channel, serving as the oven, and the column coiled on the channel with an inner diameter of 320 µm and a stationary phase of OV-1. A heating ceramic plate was affixed on the opposite side of the plate. The assembly weighed 40.3 g. The design allows for easy disassembly, or stacking of heating devices and columns, enabling flexibility in adjusting column length. When using n-C13 as the test analyte at 140 °C, a retention factor (k) was 8.5, and 7797 plates (2599 plates/m) were obtained. The assembly, employing resistance heating, demonstrated effective separation performance for samples containing alkanes, aromatics, alcohols and ketones, with good reproducibility. The reduction in theoretical plates compared to oven heating was only 2.95 %. In the boiling point range of C6 to C18, rapid temperature programming (120 °C/min) was achieved with a power consumption of 119.512 W. The assembly was successfully employed to separate benzene series compounds, gasoline and volatile organic compounds (VOCs), demonstrating excellent separation performance. This innovative design addresses the challenges of the complexity and low repeatability of the fabrication process and the high cost associated with microchip columns. Furthermore, its versatility makes it suitable for outdoor analysis applications.

Dispersant addition, but not nutrients, stimulated blooms of multiple hydrocarbonoclastic genera in nutrient-replete coastal marine surface waters.

The range of impacts of chemical dispersants on indigenous marine microbial communities and their activity remains poorly constrained. We tested the response of nearshore surface waters chronically exposed to oil leakage from a downed platform and supplied with nutrients by the Mississippi River to Corexit dispersant and nutrient additions. As assessed using 14C-labeled tracers, hexadecane mineralization potential was orders of magnitude higher in all unamended samples than in previously assessed bathypelagic communities. Nutrient additions stimulated microbial mortality but did not affect community composition and had no generalizable effect on hydrocarbon mineralization potential. By contrast, Corexit amendments caused a rapid shift in community composition and a drawdown of inorganic nitrogen and orthophosphate though no generalizable effect on hydrocarbon mineralization potential. The hydrocarbonoclastic community's response to dispersants is largely driven by the relative availability of organic substrates and nutrients, underscoring the role of environmental conditions and multiple interacting stressors on hydrocarbon degradation potential.

Comprehensive study of retention influencing gas chromatographic parameters affecting linear retention indices.

Retention in gas chromatographic systems has a central role in the identification of compounds even if detectors providing spectral information are used. But linear retention indices (LRI) of a single compound originating from multiple sources tend to vary greatly, probably due to differences in the experimental settings of the determinations. The effect of gas chromatographic parameters on LRI has been investigated using 41 compounds - previously identified from food contact plastics - and n-alkanes (n-C7-n-C40) used as reference series. As the reproducibility of LRIs under the same conditions is generally very good, the smallest changes in the settings often caused statistically significant, though irrelevant changes in the LRI values. Therefore, a multicriterial scoring-ranking system has been worked out to highlight the LRI value differences. Our results highlight that column length, heating rate, and film thickness can all be the reasons of the varying published LRI values. We also demonstrated that for the reproduction of LRI data, the chemistry (and not simply the polarity) of the stationary phase is crucial.

N-alkane shape distinctive microbial patterns in Kuroshio Extension.

Marine microorganisms are primary drivers of the elemental cycling. The interaction between heterotrophic prokaryotes and biomarker (n-alkane) in Kuroshio Extension (KE) remains unclear. Here, we categorize KE into three characteristic areas based on ocean temperatures and nutrient conditions: Cold Water Area (CWA), Mixed Area (MA), and Warm Water Area (WWA). A total of 49 samples were collected during two-year voyage to identify the source of n-alkane and associated degrading microorganisms. Total n-alkane concentrations (Σn-Alk) in surface water (SW) spanned from 1,308 ng L-1 to 1,890 ng L-1, it was significantly higher (Tukey-Kramer test, p < 0.05) in MA than CWA and WWA. The Σn-Alk in surface sediments (SS) gradually increased from north to south, ranging from 5,982 ng g-1 to 37,857 ng g-1. Bacteria and algae were the primary sources of n-alkane in both SW and SS. Proteobacteria was the most widely distributed among three areas. The presence of Rhodobacteraceae with alkB was the primary reason affecting n-alkane concentrations in SW. The Gammaproteobacteria with alkB and alkR chiefly affected n-alkane concentrations in SS. In summary, n-alkane s serve as an energy source for particular microorganisms, shaping the unique oceanographic patterns.

Characteristics of typical intermediate and semi volatile organic compounds in Shanghai during China International Import Expo event.

To ensure good air quality during the China International Import Expo (CIIE) event, stringent emission-reduction measures were implemented in Shanghai. To assess the efficacy of these measures, this study measured typical categories of intermediate/semi volatile organic compounds (I/SVOCs), including alkanes (C10-C26 n-alkanes and pristane), EPA-priority polycyclic aromatic hydrocarbons (PAHs), alkylnaphthalenes, benzothiazole (BTH) and chlorobenzenes (CBs), at an urban site of Shanghai before and during two CIIE events (2019 and 2020; non-CIIE versus CIIE). The average concentrations of alkanes and PAHs during both 2019 and 2020 CIIE events decreased by approximately 41% and 17%, respectively, compared to non-CIIE periods. However, the decline in BTH and CBs was only observed during CIIE-2019. Secondary organic aerosol (SOA) formation from alkanes, PAHs and BTH was evaluated under atmospheric conditions, revealing considerable SOA contributions from dimethylnaphthalenes and BTH. Positive matrix factorization (PMF) analysis further revealed that life-related sources, such as cooking and residential emissions, make a noticeable contribution (21.6%) in addition to the commonly concerned gasoline-vehicle sources (31.5%), diesel-related emissions (20.8%), industrial emissions (18.6%) and ship emissions (7.5%). These findings provide valuable insights into the efficacy of the implemented measures in reducing atmospheric I/SVOCs levels. Moreover, our results highlight the significance of exploring additional individual species of I/SVOCs and life-related sources for further research and policy development.

Application of various molecular markers for investigating petrogenic inputs in coastal systems strongly impacted by anthropogenic stressors.

In this study, multiple molecular markers [polycyclic aromatic hydrocarbons (PAHs), linear and branched alkanes, unresolved complex mixture (UCM), hopanes, and steranes] were applied to explore petroleum-related inputs in complex coastal systems influenced by various human-induced pressures. To investigate anthropogenic impacts related to petrogenic emissions, we analysed surface sediments from coastal areas of southern Baltic, including harbour/shipyard channels, offshore dumping sites, shipping routes, and major sinks for particulate matter discharged by large rivers. This study indicates a large spatial variability in the contamination degree of examined sites by petroleum-derived chemicals. Hopanes and steranes along with UCM appeared to have the highest potential to identify petroleum sources in studied locations, whereas investigations based on alkanes and PAHs seemed to be considerably affected by inputs of modern biogenic and combustion-derived materials, respectively. However, the combined use of all these markers provides deeper insight into the complexity of sedimentary organic matter in human-impacted environments.

History of organic pollution in montane lake Issyk-Kul, Kyrgyzstan, Central Asia, inferred from a sediment core.

In arid regions, montane lakes are valuable water sources and play important ecological roles. However, recent human-induced inputs of organic pollutants are threatening lake ecology in such regions and becoming a matter of great concern. To investigate pollutant histories and sources, we measured polycyclic aromatic hydrocarbons (PAHs) and n-alkanes in a dated sediment core that spans the last ∼350 years, from montane Lake Issyk-Kul (Kyrgyzstan, Central Asia). Results showed that organic pollutants were delivered to Lake Issyk-Kul in four stages and that their concentrations increased from Stage I (∼1670-1800 CE) to Stage IV (∼2000-2010 CE). Furthermore, we tracked the sources of sedimented PAHs using their ratios combined with n-alkanes data. Ratios of PAHs Ant/(Ant + Phe), Flt/(Flt + Pyr) and Bap/BghiP indicated that inputs during Stage II (∼1800-1970 CE) and Stage III (∼1970-2000 CE) came mainly from high-temperature combustion of coal and vehicle emissions. PAHs in Stage I and Stage IV, however, were mainly derived from low-temperature combustion and petrogenic sources. Diagnostic PAH ratios, combined with the natural n-alkane ratio (NAR＜0) and unresolved complex mixtures (UCM), showed that the sources of PAHs in Stage I were mainly from erosion of bedrock and partly influenced by forest wildfires, different from the source during Stage IV, which was mainly from refined petroleum caused by accidental spills. Our assessment of the contamination history of the lake indicates that toxicity risk to the waterbody from sediment PAHs is low, but recent discharges arising from traffic deserve attention.

Comparison of sediment biomarker signatures generated using time-integrated and discrete suspended sediment samples.

Sediment source fingerprinting using biomarker properties has led to new insights in our understanding of land use contributions to time-integrated suspended sediment samples at catchment scale. A time-integrated mass-flux sampler (TIMS; also known as the 'Phillips' sampler), a cost-effective approach for suspended sediment collection in situ. Such samplers are widely being used to collect sediment samples for source fingerprinting purposes, including studies using biomarkers as opposed to more conventional tracer properties. Here, we assessed the performance of TIMS for collecting representative sediment samples for biomarkers during high discharge events in a small lowland grassland-dominated catchment. Concentrations of long odd-chain n-alkanes (> C23) and both saturated free and bound fatty acids (C14-C32), as well as compound-specific 13C were compared between sediment collected by both TIMS and autosamplers (ISCO). The results showed that concentrations of alkanes, free fatty acids, and bound fatty acids are consistently comparable between TIMS and ISCO suspended sediment samples. Similarly, compound-specific 13C signals were not found to be significantly different in the suspended sediment samples collected using the different samplers. However, different magnitudes of resemblance in biomarker concentrations and compositions between the samples collected using the two sediment collection methods were confirmed by overlapping index and symmetric coordinates-based correlation analysis. Here, the difference is attributed to the contrasting temporal basis of TIMS (time-integrated) vs. ISCO (discrete) samples, as well as potential differences in the particle sizes collected by these different sediment sampling methods. Nevertheless, our findings suggest that TIMS can be used to generate representative biomarker data for suspended sediment samples collected during high discharge events.

Quantification of chlorinated paraffins by chromatography coupled to high-resolution mass spectrometry - Part A: Influence of gas chromatography and ionisation source parameters.

The analysis of chlorinated paraffins (CPs) has become a major analytical challenge. GC-ECNI-HRMS coupling is often used to analyse and quantify them. However, the influence of certain GC and ECNI parameters on the responses of polychlorinated n-alkanes (PCAs), the dominant components of CPs, has hardly been studied. In this paper, we investigated not only the influence of GC column characteristics, but also oven, GC inlet and source temperatures for simultaneous analysis of PCAs with chain-length ranging from 10 up to 20 carbon atoms (PCAs-C10-20). Particular attention was paid to the absolute response and PCA homologue group pattern obtained for a CP technical mixture. The optimum conditions for a wide homologue group determination were GC inlet, final gradient and ion source temperatures set at 220-240 °C, 340 °C and 200 °C. At the same time, a higher response was obtained with the Optima 5HT column compared to Optima 1 column, and with a length and film thickness of 12.5 m and 0.25 µm, respectively. The homologue group pattern of the technical mixture studied was significantly modified as a function of the source and GC inlet temperatures, film thickness and composition of the stationary phase. Here we recommend conditions that will improve the overall PCA pattern, in order to better characterise their occurrence in future environmental monitoring and exposure assessment.

Quantification of chlorinated paraffins by chromatography coupled to high-resolution mass spectrometry - Part B: Influence of liquid chromatography separation.

The analysis of chlorinated paraffins (CPs) is today an analytical challenge. Indeed, it is still impractical to describe their real composition in terms of polychlorinated alkanes (PCAs) homologue groups, which dominate technical mixtures. The co-elution of PCA congeners generates interferences due to the competition phenomena which occur during the ionisation process as well as to the dependence of the ionisation sources on the PCA chemistry. Therefore, the aim of this study was to investigate the influence of chromatographic separation, by LC-ESI-HRMS coupling, on the PCA homologue group pattern and, eventually, on their determination in food samples from interlaboratory studies. For this, three different mobile phases and six LC chromatographic columns were studied in order to optimise the analysis of CP mixtures. The first results showed that the use of a MeOH/H2O mobile phase reveals more appropriately the higher chlorinated PCAs. However, using ACN/H2O led to less ion species, with almost exclusively [M + Cl]- adducts, formed using post-column dichloromethane addition. Regarding the choice of the stationary phases, Hypercarb column provided a completely different homologue group pattern from the other chromatographic columns, in relation with the stronger retention of PCAs. Among the other columns, the C30 column better highlighted the short-chain PCAs compared to the C18 column conventionally used. Because the regulations now concern short-chain CPs, the quantification of food samples was then carried out on the C30 column. The optimised LC-ESI-HRMS conditions using C30 column and MeOH/H2O solvent mixture led to a quantification of PCAs in samples from interlaboratory studies with satisfactory accuracy (|Z-score| ≤ 2) and precision (<15%).

Levels, spatial distributions, and provision of petroleum hydrocarbons and phthalates in sediments from Obhur lagoon, Red Sea coast of Saudi Arabia.

The levels, spatial distribution, and sources of petroleum hydrocarbons and phthalates were assessed in surface sediment samples from the urban lagoon of Obhur near Jeddah, the largest city on the Red Sea coast of Saudi Arabia. The lagoon was divided into the inner zone, middle zone, and outer zone based on its geomorphological features and developmental activities. n-Alkanes, hopane and sterane biomarkers, and unresolved complex mixture were the major petroleum hydrocarbon compounds of the total extractable organic matter. Phthalates were also measured in the sediment samples. In the three zones, n-alkanes ranged from 89.3 ± 88.5 to 103.2 ± 114.9 ng/g, whereas the hopane and sterane biomarkers varied from 69.4 ± 75.3 to 77.7 ± 69.9 ng/g and 72.5 ± 77.9-89.5 ± 82.2 ng/g, respectively. The UCM concentrations ranged from 821 ± 1119 to 1297 ± 1684 ng/g and phthalates from 37.4 ± 34.5 65 ± 68 ng/g. The primary origins of these anthropogenic hydrocarbons in the lagoon sediments were petroleum products (boat engine discharges, boat washing, lubricants, and wastewater flows) and plasticizers (plastic waste and litter). The proportions of anthropogenic hydrocarbons derived from petroleum products in the sediment's TEOM ranged from 43 ± 33 to 62 ± 15%, while the percentages for plasticizers varied from 2.9 ± 1.2 to 4.0 ± 1.6%. The presence and inputs of these contaminants from petroleum and plastic wastes in the lagoon's sediments will eventually have an impact on its habitats, including the benthic nursery and spawning areas.

Organic toxicants and emerging contaminants in hospital interiors before and during the SARS-CoV2 pandemic: alkanes and PAHs.

Indoor pollution and deposition dust (DD), in particular, are acquiring concern, due to long exposure time and importance of intake by humans through contact and ingestion. Hospitals look a special category of sites, owing to peculiar contaminants affecting them and to presence of people prone to adverse effects induced by toxicants. Four in-field campaigns aimed at understanding the chemical composition of DD were performed in five Italian hospitals. Measurements were performed before (autumn 2019), during (spring 2021), and after (winter 2022) the peak of SARS-CoV2 and when restrictions caused by pandemic were revoked (winter 2023). Parallel measurements were made outdoors (2022), as well as in a university and a dwelling. Targeted contaminants were n-alkanes and polycyclic aromatic hydrocarbons (PAHs), while iso- and anteiso-alkanes were analyzed to assess the impact of tobacco smoking. Total n-alkanes ranged from 3.9 ± 2.3 to 20.5 ± 4.2 mg/g, with higher percentages of short chain homologs in 2019. PAHs ranged from 0.24 ± 0.22 to 0.83 ± 0.50 mg/g, with light congeners (≤ 228 a.m.u.) always exceeding the heavy ones (≥ 252 a.m.u.). According to carbon preference indexes, alkanes originated overall from anthropogenic sources. Microorganisms resulted to affect a hospital, and tobacco smoke accounted for ~ 4-20‰ of DD mass. As for PAH sources, the diagnostic concentration ratios suggested the concourse of biological matter burning and vehicle emission. Benzo[a]pyrene equivalent carcinogenic and mutagenic potencies of depositions at hospitals ranged ~ 9-39 µg/g and ~ 15-76 µg/g, respectively, which seems of concern for health. DD composition in hospitals was different from that outside the premises, as well as that found at university and at dwelling.

Sources and influences of atmospheric nonpolar organic compounds in Nanchang, central China: Full-year monitoring with a focus on winter pollution episodes.

Nonpolar organic compounds (NPOCs) are found in atmospheric aerosols and have significant implications for environmental and human health. Although many studies have quantitatively estimated the sources of NPOCs in different cities, few have evaluated their main influencing factors (e.g., emissions and meteorological conditions) at relatively long (e.g., different seasons) and short timescales (e.g., several days during pollution episodes). A better understanding of this issue could optimise strategies for dealing with organic contamination in atmospheric particulate matter. NPOCs (including n-alkanes, PAHs and hopanes) in fine particulate matter (PM2.5) were sampled daily at Nanchang, China, from 1 November 2020 to 31 October 2021. Analyses of specific biomarkers and diagnostic ratios indicate that the NPOCs mainly had anthropogenic sources. The quantitative estimates of a positive matrix factorization model show that fossil fuel and biomass combustion were the main sources of n-alkanes (contributing 64.8 %), while vehicle exhaust was the main source of PAHs (47.0 %) and hopanes (52.3 %). Seasonally, the contributions from coal and/or biomass combustion were higher in autumn and winter (40.2-56.3 %) than in spring and summer (25.7-44.3 %), while contributions from natural plants, petroleum volatilization and vehicle exhaust were higher in spring and summer (14.7-63.5 %) than in autumn and winter (8.1-48.9 %). Redundancy analysis shows that increased emissions, especially from coal and/or biomass combustion, are the main cause of increases in NPOCs, during both annual sampling periods and winter pollution episodes. Over the year, higher temperature and longer sunshine hours correspond to lower NPOC concentrations. In winter pollution episodes, increases in temperature and relative humidity correspond to increases in NPOC concentrations. Our results suggest that controlling primary emissions, especially from coal and biomass combustion, may be an effective way to prevent increases in NPOC concentrations.

Volatile compounds produced in smoked bacon inoculated with potential spoilage bacteria.

BACKGROUND: Volatile organic compounds (VOCs) produced during meat storage are mainly derived from the decomposition of meat components and the metabolism of spoilage bacteria. VOCs produced in sterile bacon model substrate inoculated or un-inoculated with spoilage bacteria, Staphylococcus xylosus (P2), Leuconostoc mesenteroides (P6), Carnobacterium maltaromaticum (P9), Leuconostoc gelidum (P16) and Serratia liquefaciens (P20), previously isolated, were identified by headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). Furthermore, combinations of the strains (Pm) were also obtained. RESULTS: In total, 54 volatile compounds, including aldehydes, alcohols, phenols, ketones, alkanes, alkanes, organic acids, esters and so forth, were determined after 45 days of storage in bacon inoculated with potential spoilage bacteria using the HS-SPME/GC-MS method. VOC concentrations of alcohols and organic acids in groups inoculated with bacteria were remarkably higher (P < 0.05) compared to that in control samples. Specifically, some VOCs are closely related to the metabolic activity of the inoculated bacterial strains; for example, 2,3-butanediol was associated with P2, P16 and P20, and acetic acid was mainly related to P6 and P9. CONCLUSION: The results of partial least squares regression indicated that there was a high correlation between the electronic nose sensors and VOCs of smoked inoculated potential spoilage bacteria. These compounds are potentially important for predicting deterioration of smoked bacon. © 2023 Society of Chemical Industry.

A comprehensive exploration of characteristics and source attribution of carbonaceous aerosols in PM2.5 in an East China megacity.

A total of 84 PM2.5 (fine particulate matter) aerosol samples were collected between October 2020 and August 2021 within an urban site in Hangzhou, an East China megacity. Chemical species, such as organic carbon (OC), elemental carbon (EC), as well as char, soot, and n-alkanes, were analyzed to determine their pollution characteristics and source contributions. The mean yearly concentrations of OC, EC, char, soot, and total n-alkanes (∑n-alkane) were 8.76 ± 3.61 µg/m3, 1.44 ± 0.76 µg/m3, 1.21 ± 0.69 µg/m3, 0.3 ± 0.1 µg/m3, and 24.2 ± 10.6 ng/m3. The OC, EC, and ∑n-alkanes were found in the highest levels during winter and lowest during summer. There were strong correlations between OC and EC in both winter and spring, suggesting similar potential sources for these carbonaceous components in both seasons. There were poor correlations among the target pollutants due to summertime secondary organic carbon formation. Potential source contribution functions analysis showed that local pollution levels in winter and autumn were likely influenced by long-range transportation from the Plain of North China. Source index and positive matrix factorization models provided insights into the complex sources of n-alkanes in Hangzhou. Their major contributors were identified as terrestrial plant releases (32.7%), traffic emissions (28.8%), coal combustion (27.3%), and microbial activity (11.2%). Thus, controlling vehicular emissions and coal burning could be key measures to alleviate n-alkane concentrations in the atmosphere of Hangzhou, as well as other Chinese urban centers.

Non-target screening of volatile organic compounds in spray-type consumer products and their potential health risks.

Widespread use of spray-type consumer products can raise significant concerns regarding their effects on indoor air quality and human health. In this study, we conducted non-target screening using gas chromatography-mass spectrometry (GC-MS) to analyze VOCs in 48 different spray-type consumer products. Using this approach, we tentatively identified a total of 254 VOCs from the spray-type products. Notably, more VOCs were detected in propellant-type products which are mostly solvent-based than in trigger-type ones which are mostly water-based. The VOCs identified encompass various chemical classes including alkanes, cycloalkanes, monoterpenoids, carboxylic acid derivatives, and carbonyl compounds, some of which arouse concerns due to their potential health effects. Alkanes and cycloalkanes are frequently detected in propellant-type products, whereas perfumed monoterpenoids are ubiquitous across all product categories. Among the identified VOCs, 12 compounds were classified into high-risk groups according to detection frequency and signal-to-noise (S/N) ratio, and their concentrations were confirmed using reference standards. Among the identified VOCs, D-limonene was the most frequently detected compound (freq. 21/48), with the highest concentration of 1.80 mg/g. The risk assessment was performed to evaluate the potential health risks associated with exposure to these VOCs. The non-carcinogenic and carcinogenic risks associated with the assessed VOC compounds were relatively low. However, it is important not to overlook the risk faced by occupational exposure to these VOCs, and the risk from simultaneous exposure to various VOCs contained in the products. This study serves as a valuable resource for the identification of unknown compounds in the consumer products, facilitating the evaluation of potential health risks to consumers.

Distribution, composition and risk assessment of hydrocarbon residue in surficial sediments of El-Dakhla, El-Kharga and El-Farafra oases, Egypt.

This work examined the polycyclic aromatic hydrocarbons (PAHs) and n-alkanes quantities, sources, and hazards in sediments collected from the Egyptian Western Desert Oases namely: Dakhla, Kharga and Farafra oases. The n-alkane (C9-C20) residue concentrations have ranged from 0.66 to 2417.91 µg/g recorded for the three Oases. On the other hand, the total n-alkane ranged from 448.54 µg/g to 8442.60 µg/g. Higher carbon preference index (CPI) values (> 1.0) proposed that the natural sources could be the main contributor to n-alkanes in the Oases sediment. GC-MS/MS (selected reaction monitoring (SRM) method) was used for the determination of the ΣPAHs concentrations in the studied sediments. The ΣPAHs concentrations (ng/g, dry weight) in the studied three Oases varied from 10.18 to 790.14, 10.55 to 667.72, and from 38.27 to 362.77 for the Kharga, Dakhla and Farafra Oases, respectively. The higher molecular weight PAHs were the most abundant compounds in the collected samples. Assessing potential ecological and human health issues highlighted serious dangers for living things and people. All the investigated PAHs had cancer risk values between 1.43 × 10-4 and 1.64 × 10-1, this finding suggests that PAHs in the samples under study pose a moderate risk of cancer. The main sources of PAHs in this study are biomass, natural gas, and gasoline/diesel burning emissions.