Hydrocarbon Pollution Research Articles

Nondesulfurizing benzothiophene biotransformation to hetero and homodimeric ortho-substituted diaryl disulfides by the model PAH-degrading Sphingobium barthaii.

Understanding the biotransformation mechanisms of toxic sulfur-containing polycyclic aromatic hydrocarbon (PASH) pollutants such as benzothiophene (BT) is useful for predicting their environmental fates. In the natural environment, nondesulfurizing hydrocarbon-degrading bacteria are major active contributors to PASH biodegradation at petroleum-contaminated sites; however, BT biotransformation pathways by this group of bacteria are less explored when compared to desulfurizing organisms. When a model nondesulfurizing polycyclic aromatic hydrocarbon-degrading soil bacterium, Sphingobium barthaii KK22, was investigated for its ability to cometabolically biotransform BT by quantitative and qualitative methods, BT was depleted from culture media but was biotransformed into mostly high molar mass (HMM) hetero and homodimeric ortho-substituted diaryl disulfides (diaryl disulfanes). HMM diaryl disulfides have not been reported as biotransformation products of BT. Chemical structures were proposed for the diaryl disulfides by comprehensive mass spectrometry analyses of the chromatographically separated products and were supported by the identification of transient upstream BT biotransformation products, which included benzenethiols. Thiophenic acid products were also identified, and pathways that described BT biotransformation and novel HMM diaryl disulfide formation were constructed. This work shows that nondesulfurizing hydrocarbon-degrading organisms produce HMM diaryl disulfides from low molar mass polyaromatic sulfur heterocycles, and this may be taken into consideration when predicting the environmental fates of BT pollutants.

Metagenomics reveals an abundance of black yeast-like fungi in the skin microbiome.

The skin is the first line of defence against communities of resident viruses, bacteria and fungi. The composition of the microbiome might change with factors related to the environment and host. The microbiome is dominated by bacteria. Dermatophytes and yeasts are the predominant fungi that are also involved in opportunistic infections of skin, hair and nails. Among environmental fungi, Chaetothyriales (black yeasts and relatives) are enriched by hydrocarbon pollution in domesticated habitats and comprise numerous species that cause mild-to-severe disease. We investigated the presence of black fungi in the skin microbiome by conducting an analysis in the publicly available metagenomic SRA database (NCBI). We focused on the causative agents of chromoblastomycosis and phaeohyphomycosis and used barcodes and padlock probe sequences as diagnostic tools. A total of 132,159,577 MB was analysed and yielded 18,360 reads that matched with 24 species of black fungi. Exophiala was the most prevalent genus, and Cyphellophora europaea was the most abundant species. This study reveals the abundant presence of Chaetothyriales on the skin without necessarily being associated with infection. Most of the detected causal agents are known from mild skin diseases, while also species were revealed that had been reported from CARD9-deficient patients.

Impact of petroleum refinery on aquatic ecosystem of Skikda Bay (Algeria): Diversity and abundance of viable bacterial strains

This paper reports a study on the impact of petroleum refinery effluents on the bacterial load and diversity of the aquatic ecosystem in Skikda Bay (Algeria). The results showed a large spatiotemporal variation in the isolated bacterial species. This difference between stations and seasons could be attributed to environmental factors and to the pollution rate at the different sampling sites. Statistical analysis results showed that physicochemical parameters such as pH, electrical conductivity and salinity have a very significant effect on the microbial load (p < 0.001), while hydrocarbon pollution has a significant effect on the diversity of bacterial species (p < 0.05). In total 75 bacteria were isolated from six sampling sites during the four seasons. A significant spatiotemporal richness and diversity was observed in water samples. A total of 42 strains belonging to 18 bacterial genera were identified. Most of these genera belong to the class of Proteobacteria.

Изучение влияния факторов, определяющих результаты геофизических исследований на территориях, загрязнённых лёгкими нефтепродуктами

Oil pollution significantly affects the ecosystem of underground space. The penetration of hydrocarbons into aquifers threatens to spread pollution over large areas from the source. Pollutants cause damage to natural environments and lead to damage and destruction of ecosystems. To solve environmental problems in the search for hydrocarbon pollution, geophysics is often used. In contaminated sites, knowledge of the geological structure and hydrogeological conditions, as well as the qualitative and quantitative characteristics of pollution, is essential for risk assessment and site remediation planning. Despite the fact that many geophysical methods have proven their effectiveness in solving geoecological problems, pollution of the underground environment is complex. This is primarily due to the fact that the distribution of the pollutant has an impact on both the geological and mechanical components of soils, and the biological and chemical ones. The article discusses the influence of various factors on the formation of anomalies detected by methods of shallow geophysics in the process of studying the pollution of the geological environment with oil products. The main purpose of such work is the detection, contouring and determination of the migration routes of light oil products. The paper describes several generalized models of the distribution of hydrocarbon pollution, each of which can be used to solve the set tasks, as well as be a useful tool for predicting the distribution of oil products and modeling geophysical responses from a multifactorial environment. Among the factors influencing the results of geophysical studies, a special position is occupied by biodegradation processes, as a result of which significant changes in the physical properties of the medium occur.

Evaluation of Bacillus subtilis as a Tool for Biodegrading Diesel Oil and Gasoline in Experimentally Contaminated Water and Soil.

Benzene, toluene, ethylbenzene and xylene (BTEX) are toxic petroleum hydrocarbons pollutants that can affect the central nervous system and even cause cancer. For that reason, studies regarding BTEX degradation are extremely important. Our study aimed evaluate the microorganism Bacillus subtilis as a tool for degrading petroleum hydrocarbons pollutants. Assays were run utilizing water or soil distinctly contaminated with gasoline and diesel oil, with and without B. subtilis. The ability of B. subtilis to degrade hydrophobic compounds was analyzed by Fourier-Transform Infrared Spectroscopy (FTIR) and gas chromatography. The FTIR results indicated, for water assays, that B. subtilis utilized the gasoline and diesel oil to produce the biosurfactant, and, as a consequence, performed a biodegradation process. In the same way, for soil assay, B. subtilis biodegraded the diesel oil. The gas chromatography results indicated, for gasoline in soil assay, the B. subtilis removed BTEX. So, B. subtilis was capable of degrading BTEX, producing biosurfactant and it can also be used for other industrial applications. Bioremediation can be an efficient, economical, and versatile alternative for BTEX contamination.

Experimental study and theoretical analysis on the criterion of boiling of wall film for different fuels

In direct-injection engines, the formation and vaporization of wall-attached fuel film after the spray impingement is the main factor affecting the emissions of hydrocarbon (HC), soot, and other pollutants. In response to this situation, the formation and evolution characteristics of the fuel film formed by a high-pressure spray impingement onto a heated wall were investigated. The change in the fuel film thickness during the evolution process was measured with the refractive index matching (RIM) method for three different fuels. This paper also quantitatively studied the boiling criterion of the micrometer-scale wall film at various film temperatures. The results indicate that there exists a critical film thickness to trigger the boiling phenomenon, which is closely related to the film temperature. According to the theoretical analysis, it is concluded that the critical thickness is essential for the fuel film boiling at the corresponding fuel film temperature. At the same fuel superheat degree, the critical thickness of different fuels highly relies on their physical properties, among which surface tension is the dominant factor, while the effect of saturation temperature and enthalpy of vaporization is relatively weak.

Mechanism of visible light enhances microbial degradation of Bisphenol A.

Bisphenol A (BPA) is a toxic endocrine disruptor detected in various environments. Microbial metabolic/enzymatic degradation has been thought to be the main pathway for BPA attenuation in natural environments. In this study, we found that under visible light conditions, superoxide produced by bacteria was the main reason for the rapid removal of BPA, accounting for 57% of the total removal rate. With visible light, the bacteria degraded BPA at a rate of 0.22mg/L/d, and the total removal within 8 days reached 85%, which is 4.7 times compared with that of dark culture. The intermediate product 4-iso-propenylphenol, which was considered as an end-product of microbial degradation of BPA in previous reports, was detected in large quantities at 24h in culture but gradually decreased in our experiment. Community analysis suggested bacteria with aromatic hydrocarbon degradation ability were more enriched under light incubation. Moreover, the bacteria showed well degradation ability to various pharmaceutically active but nonbiodegradable compounds including diclofenac and fluoxetine, with a removal rate of 88 % and 20%, respectively. Our study revealed the organic pollutant transformation pathway under the combined action of light and microorganisms, providing new insights into the microbial treatment of aromatic hydrocarbon pollutants.

Biodegradation and biotransformation of petroleum hydrocarbons: progress, prospects, and challenges

Oil is considered the main source of energy, being essential for the realization of various industrial activities. However, it is detrimental to the environment, since in addition to the release of polluting gases during combustion, its exploitation involves risks of water contamination, through leaks. Petroleum hydrocarbon pollutants are part of the recalcitrant compounds and their elimination from the environment causes enormous ecological impacts. The restoration of these environments is not a trivial challenge, as natural degradation, without anthropogenic involvement, depends on the nature, composition, physical and chemical properties of these compounds. Thus, bioremediation appears as alternative in the biodegradation process through the addition of microorganisms, nutrients or other substances that cause and accelerate decontamination. The advantages of these methods involve efficiency and low cost, when compared to other technologies. This work gathers knowledge about the perspectives of application of bioremediation systems in the recovery of environments polluted by petroleum hydrocarbons, discussing progress, perspectives and challenges.

Improving the uptake of PAHs by the ornamental plant Sedum spectabile using nano-SiO2 and nano-CeO2

Polycyclic aromatic hydrocarbons (PAHs) pollution is a global ecological soil problem. Screening and establishing an efficient phytoremediation system would be beneficial for alleviating this problem. The ornamental plant Sedum spectabile was selected as the remediation plant to study the removal efficiencies of PAHs after adding different concentrations of nano-SiO2, nano-CeO2, and traditional Na-montmorillonite (Na-MMT). The results demonstrated that shoot biomass was increased and photosynthesis was enhanced by the nanomaterial amendments. The uptake of 16 PAHs by S. spectabile was remarkably increased. Moreover, the two highest shoot concentrations were 7.61 (Phe) and 12.03 (Flo) times that of the control, and the two highest translocation factors were 31 (BbF) and 28 (BaP) times that of the control. Furthermore, 16S rRNA gene sequencing showed that the addition of nano-SiO2 increased the abundance of Acidobacteria, and the genera related to PAH degradation was higher under nanomaterial treatments. The very high Si concentration in the shoots of S. spectabile had a significant linear correlation with the concentration of PAHs. In conclusion, the S. spectabile remediation system assisted by two nanomaterials was effective for the removal of PAHs from soil, and the transfer of PAHs to easily harvested aboveground plant parts was especially worthy of attention.

Enhanced biodegradation of PAHs by biochar and a TiO2@biochar composite under light irradiation: Photocatalytic mechanism, toxicity evaluation and ecological response

Biochar (BC) and its composites have been widely used for pollutant treatment upon their adsorption and photocatalytic efficiency, but their toxicity and ecological effects have received little attention. In this study, BC was prepared and modified with nano-titanium dioxide to obtain BC composite (TiO2@BC), then the biotoxicity and ecological effects were investigated from two dimensions (single bacteria and microflora). In detailed, the effects of different dosage of BC and TiO2@BC on the degradation function, growth characteristics and toxicity mechanism of the strain Achromobacter sp. LH-1 were comprehensively studied. It was found that when the dosage of BC and TiO2@BC was less than or equal to 0.5 g/L, the degradation function of LH-1 was enhanced, but the effect on growth was negligible. However, when the dose exceeded 0.5 g/L, a large amount of ROS accumulated, which inhibited the cell respiratory chain and destroyed the cell wall. In another word, ·OH and ·O2– generated by BC and TiO2@BC played important roles in the inactivation of LH-1. Furthermore, a laboratory scale bioreactor (SBR) was built and applied to study the ecological effects of BC and TiO2@BC, and it was found that proper amount (0.5 g/L) of BC and TiO2@BC can not only effectively remove polycyclic aromatic hydrocarbons (PAHs) pollutants, but also increase the diversity of microbial communities, and promote the carbon and nitrogen cycle in the sewage system. This study analyzes the ecotoxicity risk of BC and TiO2@BC under photocatalysis in detail, which has important reference value for future practical applications in ecosystems.

Chronic Exposure to Low-Molecular-Weight Polycyclic Aromatic Hydrocarbons Promotes Lipid Accumulation and Metabolic Inflammation.

2-naphthol is a low-molecular-weight (LMW) polycyclic aromatic hydrocarbon (PAH) and air pollutant associated with childhood obesity. There has been a recent emergence of studies on the consequences of PAHs on human health. Current epidemiological reports suggest LMW-PAHs may contribute to obesity incidences in children, yet most studies focus on high-molecular-weight PAHs. This study explores 2-naphthol's impact on obesity and obesity-associated metabolic disorders. To investigate 2-naphthol's effect on lipid metabolism and inflammation, we employed 3T3-L1 and BAT1 cell lines to model white and brown adipocytes, respectively, alongside a murine macrophage cell line (RAW264.7). We found that 2-naphthol increased the expression of key adipogenic and lipogenic genes while decreasing lipolytic gene expression in chronically treated 3T3-L1 and BAT1 adipocytes. In addition, chronic 2-naphthol treatment also suppressed adrenergic-stimulated thermogenic gene expression in BAT1 brown adipocytes. In consistence, an increase in lipid accumulation was demonstrated in BODIPY and Oil Red O-stained adipocytes. Additionally, 3T3-L1 adipocytes and RAW264.7 macrophages chronically exposed to 2-naphthol showed upregulated mRNA expression of major inflammatory cytokines (e.g., tumor necrosis factor α (Tnfα), interleukin-1β (Il-1β), and Il-6). In summary, chronic exposure to 2-naphthol stimulates lipid accumulation in adipocytes and inflammation in adipocytes and macrophages. These findings support previous research that demonstrates 2-naphthol has obesogenic potential.

Degradation of alkane hydrocarbons by Priestia megaterium ZS16 and sediments consortia with special reference to toxicity and oxidative stress induced by the sediments in the vicinity of an oil refinery

Petroleum hydrocarbon is a critical ecological issue with impact on ecosystems through bioaccumulation. It poses significant risks to human health. Due to the extent of alkane hydrocarbon pollution in some environments, biosurfactants are considered as a new multifunctional technology for the efficient removal of petroleum-based contaminants. To this end, Yamuna river sediments were collected at different sites in the vicinity of Mathura oil refinery, UP (India). They were analysed by atomic absorption spectrophotometry and gas chromatography-mass spectrometry (GC-MS) for heavy metals and organic pollutants. Heptadecane, nonadecane, oleic acid ester and phthalic acid were detected. In total 107 bacteria were isolated from the sediments and screened for biosurfactant production. The most efficient biosurfactant producing strain was tested for its capability to degrade hexadecane efficiently at different time intervals (0 h, 7 d, 14 d and 21 d). FT-IR analysis defined the biosurfactant as lipopeptide. 16S rRNA gene sequencing identified the bacterium as Priestia megaterium. The strain lacks resistance to common antibiotics thus making it an important candidate for remediation. The microbial consortia present in the sediments were also investigated for their capability to degrade C16, C17 and C18 alkane hydrocarbons. By using gas chromatography-mass spectrophotometry the metabolites were identified as 1-docosanol, dodecanoic acid, 7-hexadecenal, (Z)-, hexadecanoic acid, docosanoic acid, 1-hexacosanal, 9-octadecenoic acid, 3-octanone, Z,Z-6,28-heptatriactontadien-2-one, heptacosyl pentafluoropropionate, 1,30-triacontanediol and decyl octadecyl ester. Oxidative stress in Vigna radiata L. roots was observed by using Confocal Laser Scanning Microscopy. A strong reduction in seed germination and radicle and plumule length was observed when Vigna radiata L. was treated with different concentrations of sediment extracts, possibly due to the toxic effects of the pollutants in the river sediments. Thus, this study is significant since it considers the toxicological effects of hydrocarbons and to degrade them in an environmentally friendly manner.

Impact of Various Transportation Modes on the Air Quality of Dhaka City: A Case Study at Motijheel

Transportation sector significantly contributes to air pollution. This study calculates the daily load of emission of some criteria pollutants (Nitrogen Oxides, Sulfur Oxides, Carbon Monoxide and Suspended Particulate Matter) and hydrocarbons from vehicular fleet at Toyenbee Circular Road, Motijheel, Dhaka. It also analyzes relative contribution of certain types of vehicles to emission of a specific type of pollutant. Primary volume data is collected from field video graphic survey and expansion factors and emission factors are taken from literature. Results show that different types of vehicles contribute to air pollution differently. For Carbon Monoxide and hydrocarbons pollution, motor cars are mainly responsible while bus is the main contributor of Nitrogen Oxides and Sulfur Oxides pollution. Motorcycle is the main contributor of Suspended Particulate Matter pollution in this case. These comparisons imply that it is necessary to determine the focus point of pollution reduction before taking any preventive measures. Journal of Engineering Science 13(2), 2022, 83-89

Integrated Photocatalytic Oxidation and Adsorption Approach for the Robust Treatment of Refinery Wastewater Using Hybrid TiO2/AC

This study reports the removal of hydrocarbon (HC) pollutants from petroleum refinery wastewater by integrated photocatalytic oxidation and adsorption using a TiO2/AC hybrid material. The hybrid adsorbent/catalyst was prepared by the impregnation of TiO2 over AC and characterized by FTIR, SEM, EDX, and XRD analyses. Under the optimized reaction conditions of pH 3, 30 °C, and 1000 mg TiO2/AC per 500 mL of sample in 50 min, the integrated photocatalytic oxidation-adsorption achieved a net percentage removal of benzene, toluene, aniline, and naphthalene of 91% from model HC solutions. Under these conditions, for the treatment of real refinery wastewater, TiO2/AC caused a 95% decrease in chemical oxygen demand (COD). The integrated photocatalytic oxidation and adsorption using TiO2/AC showed a clear advantage over the individual adsorption and photocatalytic oxidation using AC and TiO2, whereby about the same level of removal of model HCs and a decrease in the COD of refinery wastewater was attained in 105 min and 90 min, respectively, utilizing larger adsorbent/catalyst dosages. GC-MS analysis revealed that during the integrated process of adsorption-photocatalytic oxidation, all the parent HCs and oxidation byproducts were completely removed from the refinery wastewater. Based on the outstanding performance, cost-effectiveness, and environmental greenness, the newly designed TiO2/AC via the integrated adsorption-photocatalytic oxidation can be counted as an effective alternative route for the large-scale processing of refinery wastewater.

An integrated investigation of hydrocarbon pollution in Ahoada area, Niger Delta Region, Nigeria.

This study investigates hydrocarbon pollution in the Ahoada community of the Niger Delta region of Nigeria. The study uses a geographic information system (GIS) for mapping oil spill hotspots in the region. The resistivity method was used to delineate the extent of hydrocarbon pollution to a depth of 19.7m in the Ahoada area of the region. Three categories of soil samples, impacted soil (IMS), remediated soil (RS), and control soil (CS), were collected and analyzed for the presence of BTEX, PAH, TPH, TOC, and TOG. The concentrations of the samples from the IMS and RS were compared to that of the CS to determine the extent of pollution. The GIS mapping shows that the most polluted areas in the Niger Delta Region are Rivers, Bayelsa, and Delta states. Results of the geophysical images revealed contaminants' presence to depths beyond 20m at some locations in the study area. The highest depth of contaminant travel was at Ukperede. Soil samples' analysis showed that the range of concentrations of TPH in IMS at Oshie was 17.27-58.36mg/kg; RS was 11.73-50.78mg/kg which were higher than the concentrations of 0.68mg/kg in the CS. PAHs are more prevalent in Ukperede, ranging from 54.56 to 77.54mg/kg. BTEX concentrations ranged from 0.02 to 0.38mg/kg for IMP and 0.01-2.7mg/kg for RS against a CS value of 0.01mg/kg. The study revealed that there are characteristically high resistivity values in the samples which were corroborated by the findings from the resistivity survey. TOC was found to be higher in the IMS and RS than in the CS, demonstrating that a significant quantity of the hydrocarbon has undergone appreciable decomposition.

Rapid effective treatment of waxy oily sludge using a method of dispersion combined with biodegradation in a semi-fluid state

Waxy oily sludge (WOS) from petrochemical enterprises has complex components and difficult treatment. Long-term large-scale stacking has seriously threatened human health and the ecological environment. In this paper, a new rapid and effective treatment method combining dispersion and biodegradation in a semi-fluid state was developed for the WOS. The degradation mechanism of the WOS in the bioreactor was preliminarily discussed. The component analysis results showed that the compounds with large molecular weight (M ≥ 282) in the WOS accounted for more than 50%. Among all microbial consortiums, the treatment effect of the consortium FF: NY3 = 9: 1 was the best for treating the crude oil in WOS, which was significantly different from that of a single strain (p < 0.05). Under the optimal nitrogen source NH4NO3 and the concentration of rhamnolipid, the developed high-efficiency microbial consortium (FF: NY3 = 9:1) could remove 85% of the total hydrocarbon pollutants in the 20 L semi-fluid bioreactor within 9 days. The degradation characteristics of WOS components in the bioreactor showed that the developed consortium has good degradation ability for n-alkanes (about 90%), middle- (77.35%)/long-chain (72.66%) isomeric alkanes, alkenes (79.12%), alicyclic hydrocarbons (78.9%) and aromatic hydrocarbons (62.78%). The kinetic analysis results indicated that, in comparison, the middle-chain n-alkanes, middle-chain isomeric saturated alkanes, alkenes, and alicyclic hydrocarbons were most easily removed. The removal rates of long-chain n-alkanes, long-chain isomeric saturated alkanes, and aromatic hydrocarbons were relatively low. The biological toxicity test showed that the germination rate of wheat seeds in treated waxy sludge was Significantly higher than that in untreated waxy sludge (p < 0.01). These results suggest that the new method developed in this paper can treat refractory WOS quickly and effectively. This method lays the foundation for the pilot-scale treatment of the semi-fluid bioreactor.

Lagena Inferocostata – An Opportunistic Index Species of Hydrocarbon Pollutants in Gokana and Khana Local Government Areas of River State, Nigeria

Thirty shallow cores ranging from 0.0 – 1.0m and composited into upper and lower section, was studied to determine relationship between petroleum hydrocarbon pollutants and benthic foraminiferal species in order to determine an index for environmental monitoring in the study area. The core samples were taken from Gokana and Khana Local Government Areas of Rivers State, Nigeria. The cores were treated with Rose Bengal solution to distinguish between then acoenose and biocoenosis benthonic foraminiferal. The cores were analyzed for sedimentology, petroleum hydrocarbon concentrations and micropaleontology. Sedimentological descriptions of the cores indicated inhibited free flow of fluids based on the rock textures which mostly consists of clays and peaty clays. Petroleum hydrocarbons analysis consisted of Total Petroleum Hydrocarbon (TPH) and Polycyclic Aromatic Hydrocarbon (PAH). The results in concentrations of the petroleum hydrocarbons indicated higher concentrations in the upper composited sections. Total Petroleum Hydrocarbon (TPH) and Polycyclic Aromatic Hydrocarbon (PAH) ranged between (20612mg/kg – 37.09mg/kg and 9.55mg/kg – &lt;0.01mg/kg respectively) in the upper composited section and between (14731mg/kg – 14.67mg/kg and 5.71mg/kg – &lt;0.01mg/kg respectively) in the lower composited section. Occurrence of benthonic foraminiferal in the study samples is very low to barren among very low diversity. Three benthonic foraminiferal diversities were identified in the study samples and included Lagenainferocostata, Anomalinoidesspp and Ammodiscus spp. Benthonic foraminifera showed negative correlation with TPH/PAH in the presence of carcinogenic Polycyclic Aromatic Hydrocarbon (PAH) congeners except for Lagenainferocostata which increased consistently and significantly with increasing TPH/PAH in the two composited sections. This suggested Lagenainferocostata as an Index opportunistic species for the hydrocarbon polluted study area.

Multiplex SERS detection of polycyclic aromatic hydrocarbon (PAH) pollutants in water samples using gold nanostars and machine learning analysis.

Polycyclic aromatic hydrocarbons (PAHs) have attracted a lot of environmental concern because of their carcinogenic and mutagenic properties, and the fact they can easily contaminate natural resources such as drinking water and river water. This study presents a simple and sensitive point-of-care SERS detection of PAHs combined with machine learning algorithms to predict the PAH content more precisely and accurately in real-life samples such as drinking water and river water. We first synthesized multibranched sharp-spiked surfactant-free gold nanostars (GNSs) that can generate strong surface-enhanced Raman scattering (SERS) signals, which were further coated with cetyltrimethylammonium bromide (CTAB) for long-term stability of the GNSs as well as to trap PAHs. We utilized CTAB-capped GNSs for solution-based 'mix and detect' SERS sensing of various PAHs including pyrene (PY), nitro-pyrene (NP), anthracene (ANT), benzo[a]pyrene (BAP), and triphenylene (TP) spiked in drinking water and river water using a portable Raman module. Very low limits of detection (LOD) were achieved in the nanomolar range for the PAHs investigated. More importantly, the detected SERS signal was reproducible for over 90 days after synthesis. Furthermore, we analyzed the SERS data using artificial intelligence (AI) with machine learning algorithms based on the convolutional neural network (CNN) model in order to discriminate the PAHs in samples more precisely and accurately. Using a CNN classification model, we achieved a high prediction accuracy of 90% in the nanomolar detection range and an f1 score (harmonic mean of precision and recall) of 94%, and using a CNN regression model, achieved an RMSEconc = 1.07 × 10-1 μM. Overall, our SERS platform can be effectively and efficiently used for the accurate detection of PAHs in real-life samples, thus opening up a new, sensitive, selective, and practical approach for point-of-need SERS diagnosis of small molecules in complex practical environments.

Effect of diesel engine modification operated with karanja biodiesel and its blends

• Increased biodiesel blends, such as B30 and B40, result in decreased engine performance (BTE) and higher smoke, HC and NOx emissions. • The B20 blend is an appealing alternative because it enhances engine performance while lowering emissions. • The country’s economy benefits from the substitution of fossil fuels for indigenous renewable and alternative fuels. • This alternative is more realistic because there are abundant resources of non-edible oil seeds for biodiesel preparation and biodiesel production costs are becoming more affordable. Growing attention in studying renewable and alternate fuels for internal combustion (IC) engines has been increased by concerns about improving engine performance while reducing emissions to satisfy EURO standards and to fulfil increasing energy demands for a growing population. Biodiesels are a possible replacement to diesel fuel since, they are renewable and have qualities similar to fossil diesel. For diesel engines, biodiesel generated from Karanja oil is a better diesel substitute. The use of alternative fuels in a CI (Compression ignition) engine reduces performance while also increasing hydrocarbon (HC) and carbon monoxide (CO) pollutants. However, making the engine entirely adiabatic by combining biodiesel with diesel and applying thermal barrier coatings (TBC) to the piston, cylinder wall, and inlet and outlet valves will improve overall engine performance. In light of this, TBC diesel engine components coated with partly stabilized zirconia (PSZ) and aluminium oxide (Al 2 O 3 ) ceramics were tested in a diesel engine using Karanja oil methyl ester (KOME) and its mixtures. Both diesel and KOME and its blends had their brake thermal efficiency (BTE) emissions measured before and after coating, and the obtained results were matched. Engine performance is nearly comparable with acceptable emission requirements while using B20 powered biodiesel and a PSZ coated engine. Among the biodiesels tested, the maximum BTE was recorded with diesel which was 2.79%, 5.89%, 7.75%, 9.64% and 14.03% greater than B10, B20, B30, B40 and B100 fuel blends. From various fuels tested, the minimum smoke emissions were recorded with diesel which was 6.06%, 12.9%, 20.68%, 29.62% and 39.88% lower than B10, B20, B30, B40 and B100 fuel blends.

ПОЛИАРОМАТИЧЕСКИЕ УГЛЕВОДОРОДЫ В ДОННЫХ ОТЛОЖЕНИЯХ КАСПИЙСКОГО МОРЯ

In this study, variations in the levels of oil hydrocarbons and polycyclic aromatic hydrocarbons (PAHs), which are persistent organic pollutants generated by human activities, were assessed in the bottom sediments of the Caspian Sea (Russia) sampled from 2012 to 2021. The samples were analyzed for their chemical composition. The concentrations of the identified compounds responsible for hydrocarbon pollution were established. The quantitative results of the industrial environmental monitoring in the Russian sector of the Caspian Sea for subsoil use were also reviewed and processed by standard statistical methods. It was revealed that ΣPAH concentrations in the Northern and Middle Caspian Sea regions vary from analytical zero to 186.7 μg/kg and from zero to 467.8 μg/kg, respectively. The scale of oil pollution in these two regions was found to be determined by the following PAHs: phenanthrene, acenaphthene, and naphthalene. The origin of the listed PAHs provides vital information on the main sources of pollution of the Caspian Sea bottom sediments with hazardous organic substances. Based on the obtained data, the areas with background PAH pollution of the bottom sediments and those with the characteristic PAH of mainly natural and pyrogenic origin were located.