Salmonid smolt caudal fin and liver transcriptome responses to low sulfur marine diesel and high sulfur fuel oil water accommodated fractions for assessing oil spill effects in marine environments.

The environmental impact of oil spills is a critical concern, particularly pertaining to low sulfur marine diesel (LSMD) and high sulfur fuel oil (HSFO) that are commonly involved in coastal spills. Although transcriptomic biomonitoring of sentinel animals can be a powerful tool for assessing biological effects, conventional methods utilize lethal sampling to examine the liver. As a non-lethal alternative, we have previously shown salmonid caudal fin cyp1a1 is significantly responsive to LSMD-derived toxicants. The present study further investigated the transcriptomic biomonitoring potential of coho salmon smolt caudal fin in comparison to liver tissue in the context of LSMD and HSFO seawater accommodated fraction (seaWAF) exposure in cold-water marine environments. Assessing the toxicity of these seaWAFs involved quantifying polycyclic aromatic hydrocarbon (tPAH50) concentrations and generating gene expression profiles. Initial qPCR analyses revealed significant cyp1a1 response in both liver and caudal fin tissues of both genetic sexes to all seaWAF exposures. RNA-Seq analysis, focusing on the highest LSMD and HSFO seaWAF concentrations (28.4±1.8 and 645.08±146.3 µg/L tPAH50, respectively), revealed distinct tissue-specific and genetic sex-independent transcriptomic responses with an overall enrichment of oxidative stress, cell adhesion, and morphogenesis-related pathways. Remarkably, the caudal fin tissue exhibited transcriptomic response patterns comparable to liver tissue, particularly consistent differential expression of 33 gene transcripts in the liver (independent of sex and oil type) and 44 in the caudal fin. The present work underscores the viability of using the caudal fin as a non-lethal alternative to liver sampling for assessing and tracking oil spill exposure in marine environments.

Characteristics, source analysis, and health risk of PM2.5 in the urban tunnel environment associated with E10 petrol usage.

The increase in the number of motor vehicles has intensified the impact of traffic sources on air quality. Our aim was to illustrate the characteristics of PM2.5 emissions from vehicles fueled with E10 (a blend of 10% ethanol and 90% gasoline). A 21-day PM2.5 sampling in a fully enclosed urban tunnel and the component analysis were completed, and the characteristics, sources, and health risks of tunnel PM2.5 were studied. Moreover, the PM2.5 pH and its sensitivity were investigated by the thermodynamic model (ISORROPIA-II). In addition, exposure models were used to assess the health risks of different heavy metals in PM2.5 to humans through respiratory pathways. The two-point Cu/Sb ratio (entrance: 4.0 ± 1.4; exit: 4.4 ± 1.7) was close to the diagnostic criteria indicating a significant impact from brake wear. NO3-, NH4+, and SO42- constituted the main components of water-soluble ions in PM2.5 of the tunnel, accounting for 83.0-84.6% of the total concentration of inorganic ions. The organic carbon/elemental carbon ratio of the tunnel was greater than 2, indicating that the contribution of gasoline vehicle exhaust was significant. The average emission factors of PM2.5 in the fleet was 31.4 ± 16.6 mg/(veh·km). The pH value of PM2.5 in a tunnel environment (4.6 ± 0.3) was more acidic than that in an urban environment (4.9 ± 0.6). The main sensitive factors of PM2.5 pH in the urban atmosphere and tunnel environment were total ammonia (sum of gas and aerosol, NH3) and temperature, respectively. The results of the health risk assessment showed that Pb posed a potential carcinogenic risk, while As and Cd presented unacceptable risks for tunnel workers. The non-carcinogenic risk index of heavy metals of PM2.5 in the tunnel environment exceeded the safety threshold.

Assessment of genotoxicity biomarkers in gasoline station attendants due to occupational exposure.

Gasoline station attendants are exposed to numerous chemicals that might have genotoxic and carcinogenic potential, such as benzene in fuel vapor and particulate matter and polycyclic aromatic hydrocarbons in vehicle exhaust emission. According to IARC, benzene and diesel particulates are Group 1 human carcinogens, and gasoline has been classified as Group 2A "possibly carcinogenic to humans." At gas stations, self-service is not implemented in Turkey; fuel-filling service is provided entirely by employees, and therefore they are exposed to those chemicals in the workplace during all working hours. Genetic monitoring of workers with occupational exposure to possible genotoxic agents allows early detection of cancer. We aimed to investigate the genotoxic damage due to exposures in gasoline station attendants in Turkey. Genotoxicity was evaluated by the Comet, chromosomal aberration, and cytokinesis-block micronucleus assays in peripheral blood lymphocytes. Gasoline station attendants (n = 53) had higher tail length, tail intensity, and tail moment values than controls (n = 61). In gasoline station attendants (n = 46), the frequencies of chromatid gaps, chromosome gaps, and total aberrations were higher compared with controls (n = 59). Increased frequencies of micronuclei and nucleoplasmic bridges were determined in gasoline station attendants (n = 47) compared with controls (n = 40). Factors such as age, duration of working, and smoking did not have any significant impact on genotoxic endpoints. Only exposure increased genotoxic damage in gasoline station attendants independently from demographic and clinical characteristics. Occupational exposure-related genotoxicity risk may increase in gasoline station attendants who are chronically exposed to gasoline and various chemicals in vehicle exhaust emissions.

Source analysis and health risk assessment of polycyclic aromatic hydrocarbon (PAHs) in total suspended particulate matter (TSP) from Bengbu, China.

The polycyclic aromatic hydrocarbon (PAH) concentrations in total suspended particulate matter (TSP) samples collected from October, 2021 to September, 2022 were analyzed to clarify the pollution characteristics and sources of 16 PAHs in the atmospheric TSP in Bengbu City. The ρ(PAHs) concentrations ranged from 1.71 to 43.85 ng/m3 and higher concentrations were detected in winter, followed by spring, autumn, and summer. The positive matrix factorization analysis revealed that, in spring and summer, PAH pollution was caused mainly by industrial emissions, gasoline and diesel fuel combustion, whereas in autumn and winter, it was coal, biomass and natural gas combustion. The cluster and potential source factor analyses showed that long-range transport was a significant factor. During spring, autumn, and winter, the northern and northwestern regions had a significant impact, whereas the coastal area south of Bengbu had the greatest influence in summer. The health risk assessment revealed that the annual total carcinogenic equivalent concentration values for PAHs varied from 0.0159 to 7.437 ng/m3, which was classified as moderate. Furthermore, the annual incremental lifetime cancer risk values ranged from 1.431 × 10-4 to 3.671 × 10-3 for adults and from 6.823 × 10-5 to 1.749 × 10-3 for children, which were higher than the standard.

Electrification of Transit Buses in the United States Reduces Greenhouse Gas Emissions.

The transportation sector is the largest emitter of greenhouse gas emissions (GHGs) in the United States. Increased use of public transit and electrification of public transit could help reduce these emissions. The electrification of public transit systems could also reduce air pollutant emissions in densely populated areas, where air pollution disproportionally burdens vulnerable communities with high health impacts and associated social costs. We analyze the life cycle emissions of transit buses powered by electricity, diesel, gasoline, and compressed natural gas and model GHGs and air pollutants mitigated for a transition to a fully electric U.S. public transit bus fleet using transit agency-level data. The electrification of the U.S. bus fleet would reduce several conventional air pollutants and has the potential to reduce transit bus GHGs by 33-65% within the next 14 years depending on how quickly the transition is made and how quickly the electricity grid decarbonizes. A levelized cost of driving analysis shows that with falling capital costs and an increase in annual passenger-kilometers of battery electric buses, the technology could reach levelized cost parity with diesel buses when electric bus capital costs fall below about $670 000 per bus.

Catalytic flash pyrolysis of Scenedesmus sp. post-extraction residue using low-cost HZSM-5 catalyst with the perspective to produce renewable aromatic hydrocarbons.

Recovering renewable chemicals from de-fatted microalgal residue derived from lipid extraction within the algal-derived biofuel sector is crucial, given the rising significance of microalgal-derived biodiesel as a potential substitute for petroleum-based liquid fuels. As a circular economy strategy, effective valorization of de-fatted biomass significantly improves the energetic and economic facets of establishing a sustainable algal-derived biofuel industry. In this scenario, this study investigates flash catalytic pyrolysis as a sustainable pathway for valorizing Scenedesmus sp. post-extraction residue (SPR), potentially yielding a bio-oil enriched with upgraded characteristics, especially renewable aromatic hydrocarbons. In the scope of this study, volatile products from catalytic and non-catalytic flash pyrolysis were characterized using a micro-furnace type temperature programmable pyrolyzer coupled with gas chromatographic separation and mass spectrometry detection (Py-GC/MS). Flash pyrolysis of SPR resulted in volatile products with elevated oxygen and nitrogen compounds with concentrations of 46.4% and 26.4%, respectively. In contrast, flash pyrolysis of lyophilized microalgal biomass resulted in lower concentrations of these compounds, with 40.9% oxygen and 17.3% nitrogen. Upgrading volatile pyrolysis products from SPR led to volatile products comprised of only hydrocarbons, while completely removing oxygen and nitrogen-containing compounds. This was achieved by utilizing a low-cost HZSM-5 catalyst within a catalytic bed at 500 °C. Catalytic experiments also indicate the potential conversion of SPR into a bio-oil rich in monocyclic aromatic hydrocarbons, primarily BETX, with toluene comprising over one-third of its composition, thus presenting a sustainable pathway for producing an aromatic hydrocarbon-rich bio-oil derived from SPR. Another significant finding was that 97.8% of the hydrocarbon fraction fell within the gasoline range (C5-C12), and 35.5% fell within the jet fuel range (C8-C16). Thus, flash catalytic pyrolysis of SPR exhibits significant promise for application in drop-in biofuel production, including green gasoline and bio-jet fuel, aligning with the principles of the circular economy, green chemistry, and bio-refinery.

Optimization and screening of process parameters for the robust co-pyrolytic study of waste motor oil and rice stubble toward sustainable waste-to-fuel generation.

The current study explores the co-pyrolysis of waste motor oil (WMO) and rice stubble in a designed lab-scale pyrolyzer to produce alternative energy fuels. The parameter screening was followed by optimization utilizing the Box-Behnken design (BBD). Reactor temperature (TR), mixing ratio (M), and holding time (t) affected the co-pyro-oil yield substantially. A maximum co-pyro-oil yield of 90.3% was achieved at a TR = 485 °C, t = 12.5 min, and M = 5% rice stubble to waste motor oil, which was further characterized and compared with the commercial diesel fuel properties. The highest research octane number of 76.15 was obtained for the co-pyro-oil (Co-PO), followed by the pyro-oil generated from only waste motor oil (POWMO). Consequently, the paraffin content increased to 64.34 wt% from 27.66 wt % for PO RS. The carbon number varied from C7-C17 for PO WMO and Co-Po, aligning with the diesel fuel requirements. Furthermore, a substantial enrichment in the physio-chemical properties of the produced Co-PO with reduced moisture content and enhancement in higher heating value (HHV) was also noticed. Hence, the generated Co-PO could be utilized as transport-grade fuel.

Mediation effect of serum zinc on insulin secretion inhibited by methyl tert-butyl ether in gas station workers.

Methyl tert-butyl ether (MTBE), a type of gasoline additive, has been found to affect insulin function and glucose homeostasis in animal experiments, but there is still no epidemiological evidence. Zinc (Zn) is a key regulatory element of insulin secretion and function, and Zn homeostasis can be disrupted by MTBE exposure through inducing oxidative stress. Therefore, we suspected that Zn might be involved and play an important role in the process of insulin secretion inhibited by MTBE exposure. In this study, we recruited 201 male subjects including occupational and non-occupational MTBE exposure from Anhui Province, China in 2019. Serum insulin and functional analog fibroblast growth factor 1 (FGF1) and blood MTBE were detected by Elisa and headspace solid-phase microextraction and gas chromatography-high-resolution mass spectrometry. According to MTBE internal exposure level, the workers were divided into low- and high-exposed groups and found that the serum insulin level in the high-exposed group was significantly lower than that in the low-exposed group (p = 0.003) while fasting plasma glucose (FPG) level increased obviously in the high-exposed group compared to the low-exposed group (p = 0.001). Further analysis showed that MTBE exposure level was positively correlated with FPG level, but negatively correlated with serum insulin level, which suggested that the FPG level increase might be related to the decrease of serum insulin level induced by MTBE exposure. The results of further mediation effect analysis showed that changes in serum zinc levels played a major intermediary role in the process of insulin secretion inhibition and blood glucose elevation caused by MTBE exposure. In addition, a significant negative correlation was found between MTBE exposure and serum Zn level, which might play a strong mediating effect on the inhibition of insulin secretion induced by MTBE exposure. In conclusion, our study provided evidence that MTBE could inhibit insulin secretion and interfere with Zn metabolism in gas station workers for the first time, and found that Zn might play an important mediation effect during the process of inhibiting insulin secretion and interfering with glucose metabolism induced by MTBE exposure.

Predicting and assessing greenhouse gas emissions during the construction of monorail systems using artificial intelligence.

Based on partial data, this paper uses BP neural network optimised by particle swarm optimisation algorithm to predict the total greenhouse gas (GHG) emissions of the line in the construction phase. The GHG emission efficiency is analysed by SBM (Slacks-Based Measure) super efficiency method. Finally, the grey relational analysis (GRA) is applied to sort the GHG emission correlation factors. Based on the existing design and quota document data of 16 stations and 16 sections of the Wuhu Monorail Line 1, we have employed a neural network optimized by particle swarm optimization algorithm to predict the total emissions of greenhouse gases during the construction phase of the entire line consisting of 25 stations and 24 sections. The GHG emissions of all stations and sections are 29,300 tons and 21,000 tons. The technical efficiency, pure technical efficiency, and scale efficiency of the stations and sections were high. As for stations, the order of influence degree is metal material consumption (0.9731) > cost (0.9486) > electric energy consumption (0.9481) > station area (0.9109) > concrete and cement consumption (0.9032) > other material consumption (0.8831) > gasoline and diesel consumption (0.7258). For the section, the order of influence degree is cost (0.9766) > concrete (0.9581) > steel reinforcement (0.9483) > other steels (0.874) > section length (0.8337) > power energy consumption (0.7169) > wood consumption (0.6684).

Comparing different methods for olefin quantification in pygas and plastic pyrolysis oils: Gas chromatography-vacuum ultraviolet detection versus comprehensive gas chromatography versus bromine number titration.

In steam cracking, upstream pyrolysis oil hydroprocessing, and in many downstream processes, olefinic content is key to assess process performance and process safety risk associated with highly exothermic reactions. When looking to plastic pyrolysis oils as a potential feedstock, as well as downstream products such as pyrolysis gasoline (pygas), these materials contain unsaturated hydrocarbons which are not present in fossil feedstocks. Pygas is a product of pyrolysis and exhibits a large number of chemical structural similarities with plastic pyrolysis oils, especially in terms of olefins structure. Quantification of the unsaturation content (olefins and di-olefins) is extremely important in industry, hence the focus of this manuscript. Detailed hydrocarbon analysis with flame ionization detection is inadequate to fully characterize the hydrocarbon composition of such samples, especially when peaks are closely eluting, or even co-eluting. In this study, the gas chromatography coupled to vacuum ultraviolet (GC-VUV) detection method previously described for the analysis of liquid hydrocarbon streams1 and plastic pyrolysis oils2 has been compared with comprehensive gas chromatography (GC × GC) and the industry standard for olefin quantification (i.e., bromine number titration). Although based on different methodologies, a correlation between the olefin content obtained from GC-VUV and the bromine number titration method is hereby presented.

Investigation on formaldehyde generation characteristics and influencing factors of PODE/methanol dual-fuel combustion mode.

Polyoxymethylene dimethyl ether (PODE) and methanol are important low-carbon substitutable fuels for reducing carbon emissions in internal combustion engines. In the research, the impacts of methanol ratio, injection timing, and intake temperature on HCHO generation and emission were investigated using both engine tests and numerical simulations. Results suggest that an increase in methanol ratio suppresses auto-ignition tendency of PODE, leading to the increase of ignition delay period, pressure peak, and heat release rate peak inside the cylinder. The decrease in in-cylinder combustion temperature contributes to an increase in HCHO emission due to partial oxidation of methanol in the cylinder and exhaust pipe. While the injection timing is gradually postponed from -10 °CA ATDC to 2 °CA ATDC, in-cylinder high-temperature area decreases, the quantity of unburned methanol increases, but part of HCHO is converted to HCO due to H radical influence, resulting in 72% increased HCHO emission. With the increment of intake temperature, the oxidation and decomposition of in-cylinder methanol accelerate, leading to an improvement in combustion stability, more uniform temperature distribution, and a decrease in unburned methanol, which results in lower HCHO emission. When the intake temperature is rose from 30 to 60 °C, HCHO emission decreases by 11.2%.

Critical review on the formations and exposure of polycyclic aromatic hydrocarbons (PAHs) in the conventional hydrocarbon-based fuels: Prevention and control strategies.

Polycyclic aromatic hydrocarbons (PAHs) are widely present in the atmosphere and primarily originate from the incomplete burning of fossil fuels and biofuels. Exposure to PAHs leads to harmful effects on human health and the environment. Diesel engines are a major source of PAH production in the transportation sector. Various approaches have been employed to reduce PAH emissions from diesel engines, including the use of biodiesel, green gaseous fuels, exhaust gas recirculation, exhaust after-treatment, and genetically modifying biodiesel with nanoparticles. This review focuses on PAH emissions from different generations of fuels and examines the remedial control actions taken to mitigate PAH formation. The study underscores the necessity for effective regulation of emissions from diesel engines, especially in developing countries where the reliance on fossil fuels is significant. Biodiesel has shown promise in reducing PAHs and carcinogenic pollutants, with higher biodiesel concentrations resulting in lower PAH formation. Replacing diesel with biodiesel and optimizing engine operating conditions are feasible methods to reduce PAH levels in the atmosphere. The use of nanoparticles in fuel blends and higher oxygen content in combustion chambers are also considered potential strategies for pollutant reduction. Additionally, the utilization of hydrogen and ammonia as secondary fuels has been explored as promising alternatives to fossil fuels. The study highlights the importance of further research on the presence of residual PAHs in the atmosphere and the implementation of strategies to curtail vehicular emissions.

The occurrence, sources, and health risks of substituted polycyclic aromatic hydrocarbons (SPAHs) cannot be ignored.

Similar to parent polycyclic aromatic hydrocarbons (PPAHs), substituted PAHs (SPAHs) are prevalent in the environment and harmful to humans. However, they have not received much attention. This study investigated the occurrence, distribution, and sources of 10 PPAHs and 15 SPAHs in soil, water, and indoor and outdoor PM2.5 and dust in high-exposure areas (EAH) near industrial parks and low-exposure areas (EAL) far from industrial parks. PAH pollution in all media was more severe in the EAH than in the EAL. All SPAHs were detected in this study, with alkylated and oxygenated PAHs being predominant. Additionally, 3-OH-BaP and 1-OH-Pyr were detected in all dust samples in this study, and 6-N-Chr, a compound with carcinogenicity 10 times higher than that of BaP, was detected at high levels in all tap water samples. According to the indoor-outdoor ratio, PAHs in indoor PM2.5 in the EAH mainly originated from indoor pollution sources; however, those in the EAL were simultaneously affected by indoor-outdoor air exchange and indoor sources. Most target PAHs tended to deposit from air to dust, and this tendency was significantly negatively associated with the octanol-air partitioning coefficient of PAHs. SPAHs in the environment are primarily derived from the petroleum industry and the mixed combustion of gasoline, biomass, and coal. The toxicity equivalence factors of SPAHs were predicted using QSAR models to assess their lifetime carcinogenic risk (ILCR). The ILCRtotal from PAHs for adults in the EAH was >10-4. Though the levels of 6-N-Chr and 1-Me-Pyr in the environment were markedly lower than those of PPAHs, their ILCRs from PM2.5 inhalation and dermal contact with water exceeded 10-6. This study is significant for recognizing and controlling the health risks associated with SPAHs in humans.

Exceedances of Secondary Aerosol Formation from In-Use Natural Gas Heavy-Duty Vehicles Compared to Diesel Heavy-Duty Vehicles.

This work, for the first time, assessed the secondary aerosol formation from both in-use diesel and natural gas heavy-duty vehicles of different vocations when they were operated on a chassis dynamometer while the vehicles were exercised on different driving cycles. Testing was performed on natural gas vehicles equipped with three-way catalysts (TWCs) and diesel trucks equipped with diesel oxidation catalysts, diesel particulate filters, and selective catalytic reduction systems. Secondary aerosol was measured after introducing dilute exhaust into a 30 m3 environmental chamber. Particulate matter ranged from 0.18 to 0.53 mg/mile for the diesel vehicles vs 1.4-85 mg/mile for the natural gas vehicles, total particle number ranged from 4.01 × 1012 to 3.61 × 1013 for the diesel vehicles vs 5.68 × 1012-2.75 × 1015 for the natural gas vehicles, and nonmethane organic gas emissions ranged from 0.032 to 0.05 mg/mile for the diesel vehicles vs 0.012-1.35 mg/mile for the natural gas vehicles. Ammonia formation was favored in the TWC and was found in higher concentrations for the natural gas vehicles (ranged from ∼0 to 1.75 g/mile) than diesel vehicles (ranged from ∼0 to 0.4 g/mile), leading to substantial secondary ammonium nitrate formation (ranging from 8.5 to 98.8 mg/mile for the natural gas vehicles). For the diesel vehicles, one had a secondary ammonium nitrate of 18.5 mg/mile, while the other showed essentially no secondary ammonium nitrate formation. The advanced aftertreatment controls in diesel vehicles resulted in almost negligible secondary organic aerosol (SOA) formation (ranging from 0.046 to 2.04 mg/mile), while the natural gas vehicles led to elevated SOA formation that was likely sourced from the engine lubricating oil (ranging from 3.11 to 39.7 mg/mile). For two natural gas vehicles, the contribution of lightly oxidized lubricating oil in the primary organic aerosol was dominant (as shown in the mass spectra analysis), leading to enhanced SOA mass. Heavily oxidized lubricating oil was also observed to contribute to the SOA formation for other natural gas vehicles.

GASOLINE: detecting germline and somatic structural variants from long-reads data.

Long-read sequencing allows analyses of single nucleic-acid molecules and produces sequences in the order of tens to hundreds kilobases. Its application to whole-genome analyses allows identification of complex genomic structural-variants (SVs) with unprecedented resolution. SV identification, however, requires complex computational methods, based on either read-depth or intra- and inter-alignment signatures approaches, which are limited by size or type of SVs. Moreover, most currently available tools only detect germline variants, thus requiring separate computation of sample pairs for comparative analyses. To overcome these limits, we developed a novel tool (Germline And SOmatic structuraL varIants detectioN and gEnotyping; GASOLINE) that groups SV signatures using a sophisticated clustering procedure based on a modified reciprocal overlap criterion, and is designed to identify germline SVs, from single samples, and somatic SVs from paired test and control samples. GASOLINE is a collection of Perl, R and Fortran codes, it analyzes aligned data in BAM format and produces VCF files with statistically significant somatic SVs. Germline or somatic analysis of 30[Formula: see text] sequencing coverage experiments requires 4-5 h with 20 threads. GASOLINE outperformed currently available methods in the detection of both germline and somatic SVs in synthetic and real long-reads datasets. Notably, when applied on a pair of metastatic melanoma and matched-normal sample, GASOLINE identified five genuine somatic SVs that were missed using five different sequencing technologies and state-of-the art SV calling approaches. Thus, GASOLINE identifies germline and somatic SVs with unprecedented accuracy and resolution, outperforming currently available state-of-the-art WGS long-reads computational methods.

Characterization of Biodiesel and Diesel Combustion Particles: Chemical Composition, Lipid Metabolism, and Implications for Health and Environment.

Biodiesel, derived from alkyl esters of vegetable oils or animal fats, has gained prominence as a greener alternative to diesel due to its reduced particle mass. However, it remains debatable whether biodiesel exposure has more severe health issues than diesel. This study performed high-resolution mass spectrometry to examine the detailed particle chemical compositions and lipidomics analysis of human lung epithelial cells treated with emissions from biodiesel and diesel fuels. Results show the presence of the peak substances of CHO compounds in biodiesel combustion that contain a phthalate ester (PAEs) structure (e.g., n-amyl isoamyl phthalate and diisobutyl phthalate). PAEs have emerged as persistent organic pollutants across various environmental media and are known to possess endocrine-disrupting properties in the environment. We further observed that biodiesel prevents triglyceride storage compared to diesel and inhibits triglycerides from becoming phospholipids, particularly with increased phosphatidylglycerols (PGs) and phosphatidylethanolamines (PEs), which potentially could lead to a higher probability of cancer metastasis.

Biodiesel production from Mastic oil via electrolytic transesterification: optimization using response surface methodology and engine test.

This study aimed to synthesize the biodiesel from Mastic oil by electrolysis method. Mastic gum is a potential and inexpensive feedstock for the biodiesel production. The oil content of Mastic gum was ~ 20% of the total gum weight. The gas chromatography-mass spectrometry (GC-MS) analysis was exploited to measure the oil's fatty acid profile. The response surface methodology (RSM) via Box-Behnken design (BBD) was utilized to specify the best processing condition of the electrolytic transesterification process. According to the RSM-BBD results, the highest predicted biodiesel yield was 95% at the reaction time of 1 h, methanol to oil ratio of 4:1, and catalyst weight of 1.2 wt%. Under these conditions, the produced Mastic oil biodiesel was blended with the neat diesel at different volume ratios of 5:95 (B5), 10:90 (B10), and 15:85 (B15). These fuel mixtures were tested in a single-cylinder engine to assess engine performance and exhaust emissions. The experiments exhibited that blending biodiesel with diesel can slightly improve the engine performance. Moreover, the application of blends with high volumes of biodiesel decreased the exhaust emissions, such as carbon monoxide (CO), carbon dioxide (CO2), and unburned hydrocarbons (UHC) by 54.54%, 41%, and 39.3%, respectively. However, the nitrogen oxide (NOx) emission increased because of the higher oxygen content of the biodiesel. It was also found that the physical and chemical characteristics of the Mastic oil biodiesel are the same as diesel, consistent with the ASTM standard. The Fourier transform infrared (FTIR) analysis also confirmed the biodiesel production.

Exhaust particle number and composition for diesel and gasoline passenger cars under transient driving conditions: Real-world emissions down to 1.5 nm.

Recent recommendations given by WHO include systematic measurements of ambient particle number concentration and black carbon (BC) concentrations. In India and several other highly polluted areas, the air quality problems are severe and the need for air quality related information is urgent. This study focuses on particle number emissions and BC emissions of passenger cars that are technologically relevant from an Indian perspective. Particle number and BC were investigated under real-world conditions for driving cycles typical for Indian urban environments. Two mobile laboratories and advanced aerosol and trace gas instrumentation were utilized. Our study shows that passenger cars without exhaust particle filtration can emit in real-world conditions large number of particles, and especially at deceleration a significant fraction of particle number can be even in 1.5-10 nm particle sizes. The mass concentration of exhaust plume particles was dominated by BC that was emitted especially at acceleration conditions. However, exhaust particles contained also organic compounds, indicating the roles of engine oil and fuel in exhaust particle formation. In general, our study was motivated by serious Indian air quality problems, by the recognized lack of emission information related to Indian traffic, and by the recent WHO air quality guidance; our results emphasize the importance of monitoring particle number concentrations and BC also in Indian urban areas and especially in traffic environments where people can be significantly exposed to fresh exhaust emissions.

Emission Measurements on a Large Sample of Heavy-Duty Diesel Trucks in China by Using Mobile Plume Chasing.

Real-world heavy-duty diesel trucks (HDTs) were found to emit far more excess nitrogen oxides (NOX) and black carbon (BC) pollutants than regulation limits. It is essential to systematically evaluate on-road NOX and BC emission levels for mitigating HDT emissions. This study launched 2109 plume chasing campaigns for NOX and BC emissions of HDTs across several regions in China from 2017 to 2020. It was found that NOX emissions had limited reductions from China III to China V, while BC emissions of HDTs exhibited high reductions with stricter emission standard implementation. This paper showed that previous studies underestimated 18% of NOX emissions in China in 2019 and nearly half of the real-world NOX emissions from HDTs (determined by updating the emission trends of HDTs) exceeded the regulation limits. Furthermore, the ambient temperature was identified as a primary driver of NOX emissions for HDTs, and the low-temperature penalty has caused a 9-29% increase in NOX emissions in winter in major regions of China. These results would provide important data support for the precise control of the NOX and BC emissions from HDTs.

Life Cycle Greenhouse Gas Emissions of Brazilian Sugar Cane Ethanol Evaluated with the GREET Model Using Data Submitted to RenovaBio.

Brazil is the second-largest ethanol producer in the world, primarily using sugar cane as feedstock. To foster biofuel production, the Brazilian government implemented a national biofuel policy, known as RenovaBio, in which greenhouse gas (GHG) emission reduction credits are provided to biofuel producers based on the carbon intensities (CI) of the fuels they produce. In this study, we configured the GREET model to evaluate life cycle GHG emissions of Brazilian sugar cane ethanol, using data from 67 individual sugar cane mills submitted to RenovaBio in 2019/2020. The average CI per megajoule of sugar cane ethanol produced in Brazil for use in the U.S. was estimated to be 35.2 g of CO2 equivalent, a 62% reduction from U.S. petroleum gasoline blendstock without considering the impacts of land use change. The three major GHG sources were on-field N2O emissions (24.3%), sugar cane farming energy use (24.2%), and sugar cane ethanol transport (19.3%). With the probability density functions for key input parameters derived from individual mill data, we performed stochastic simulations with the GREET model to estimate the variations in sugar cane ethanol CI and confirmed that despite the larger variations in sugar cane ethanol CI, the fuel provided a robust GHG reduction benefit compared to gasoline blendstock.