Individual Hydrocarbons Research Articles

Sorption and Reaction of Biomass Derived HC Blends and Their Constituents on a Commercial Pt–Pd/Al2O3 Oxidation Catalyst

Within the Research Cluster of Excellence “The Fuel Science Center” at RWTH Aachen University, the production and application of new fuels from bio-based carbon feedstocks and CO2 with hydrogen from renewable electricity generation is being investigated. In this study, the storage and oxidation of ethanol, 1-butanol, 2-butanone, cyclopentanone, and cyclopentane as well as two blends thereof on a series production Pt–Pd/Al2O3 oxidation catalyst were investigated. Hydrocarbon (HC) storage and temperature-programmed surface reaction (TPSR) experiments were carried out to analyze their adsorption and desorption behavior. In addition, the individual HCs and both blends were investigated using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (TP-DRIFTS). In general, all oxygenated HCs are adsorbed more strongly than cyclopentane due to their higher polarity. Interestingly, it could be observed that the two different blends [blend 1: ethanol (50 mol %), 2-butanone (21 mol %), cyclopentanone (14 mol %) and cyclopentane (15 mol %); blend 2: 1-butanol (45 mol %), ethanol (29 mol %) and cyclopentane (27 mol %)] exhibit a different storage behavior compared to the single hydrocarbons. It was shown that the presence of 1-butanol and cyclopentane in blend 2 strongly inhibits the oxidation of ethanol. As a result, the ethanol light-off temperature was increased by at least 100 K. A difference was also found in the storage behavior of cyclopentane. While no significant storage could be detected in the pure compound experiment, the experiments with both mixtures showed a larger amount stored. The presence of adsorbed species of the hydrocarbons and their corresponding reaction products has been demonstrated and gives an insight into the storage mechanism of blends.Graphic

Determining the Temperature Dependency of Biodegradation Kinetics for 34 Hydrocarbons while Avoiding Chemical and Microbial Confounding Factors.

Biodegradation kinetics data are keystone for evaluating the environmental persistence and risk of chemicals. Biodegradation kinetics depend highly on the prevailing temperature, which influences microbial community structures, metabolic rates, and chemical availability. There is a lack of high-quality comparative biodegradation kinetics data that are determined at different test temperatures but with the same microbial inoculum and chemical availability. The present study was designed to determine the effect of test temperature on the biodegradation kinetics of hydrocarbons while avoiding confounding factors. We used inocula from a Northern river (2.7 °C) and a Central European river (12.5 °C). Aqueous stock solutions containing 45 individual hydrocarbons were generated by passive dosing and added to river water containing the native microorganisms. Compound-specific biodegradation kinetics were then determined at 2.7, 12, and 20 °C based on substrate depletion. Main findings comprise the following: (1) Degradation half-times (DegT50) of 34 test chemicals were determined at different test temperatures and were largely consistent with the Arrhenius equation (activation energy, 65.4 kJ/mol). (2) Differences in biodegradation kinetics between tested isomers were rather limited. (3) The recent lowering of standard test temperature from 20 to 12 °C results typically in a doubling of DegT50 values and can lead to a stricter persistency assessment.

Distribution of Polycyclic Aromatic Hydrocarbons in Surface Water and Fishes in Bodo/Bonny River Nigeria

Several industrial activities around the Niger Delta region have contributed to the widespread contamination of marine ecosystems with organochlorine compounds (OCs), petroleum products that are a source of polycyclic aromatic hydrocarbons (PAHs). These pollutants tend to be persistent in the environment and are also often highly toxic to the biota. The study was therefore, aimed at determining the concentrations of organic pollutants (PAHS) in the Bodo/Bonny coastal waters and their effect on the marine ecosystems. This is exacerbated by the risks posed by polycyclic aromatic hydrocarbons (PAHs) in oil spilled environments. Surface water, sediment and fish samples were collected from different sampling stations along the river and analyzed using standard analytical methods. Sampling of surface water was done on Link fish pond which served as control. The results of the value of TPH ranged from 0.31 to 40.85 mg/l, PAHs range from 2.06 to 2.73 mg/l and BTEX ranged from 0.043 to 0.081 mg/l. The Total Petroleum hydrocarbon (TPH) values obtained were above DPR permissible Limit of 20 mg/l in all the stations. However, values of individual polycyclic aromatic hydrocarbons show that Benzo(a) anthracene had the highest concentration especially in all the surface water stations sampled. Also results showed a presence of carcinogenic PAHs in the fish tissues. This still poses a danger if accumulation was to take place over a long period of time. The values obtained from this study stations also exceeded the WHO quality criteria for drinking, aquatic life support and recreation. This reveals that Bodo/Bonny River is under pollution threat and underscore the need for early remediation if adverse health defects are to be prevented.

Virtual Soft Sensor of the Feedstock Composition of the Catalytic Reforming Unit

The paper discusses a method for obtaining a matrix of individual and group composition of a hydrotreated heavy gasoline fraction in industrial conditions based on the fractional composition obtained by the distillation method according to the ASTM D86 (the Russian analogue of such a standard is GOST 2177). A method for bounds estimation of the retention index (RI) change is considered on the basis of the symmetry of the RI change range relative to its arithmetic mean. Implementation of this method is performed by simulation of individual composition of C6–C12 feedstock of the catalytic reforming unit in the software package. For this purpose, the boiling curve of individual composition of hydrocarbon mixture is converted into the corresponding curve of fractional composition. The presented technique of creating a virtual soft sensor makes it possible to establish a correct relationship between the fractional composition and the individual hydrocarbon composition obtained according to the IFP 9301 (GOST R 52714) (Russian GOST R 52714 and international IFP 9301 standards for the determination of individual and group composition of hydrocarbon mixtures by capillary gas chromatography). The virtual soft sensor is based on chemical and mathematical principles. The application of this technique on the data of a real oil refinery is shown. Obtaining accurate data by means of a virtual soft sensor on the individual composition of feedstock will make it possible to optimize the catalytic reforming process and thus indirectly improve its environmental friendliness and enrichment efficiency.

Conversion of Polyethylene Waste into Gaseous Hydrocarbons via Integrated Tandem Chemical–Photo/Electrocatalytic Processes

The chemical inertness of polyethylene makes chemical recycling challenging and motivates the development of new catalytic innovations to mitigate polymer waste. Current chemical recycling methods yield a complex mixture of liquid products, which is challenging to utilize in subsequent processes. Here, we present an oxidative depolymerization step utilizing diluted nitric acid to convert polyethylene into organic acids (40% organic acid yield), which can be coupled to a photo- or electrocatalytic decarboxylation reaction to produce hydrocarbons (individual hydrocarbon yields of 3 and 20%, respectively) with H2 and CO2 as gaseous byproducts. The integrated tandem process allows for the direct conversion of polyethylene into gaseous hydrocarbon products with an overall hydrocarbon yield of 1.0% for the oxidative/photocatalytic route and 7.6% for the oxidative/electrolytic route. The product selectivity is tunable with photocatalysis using TiO2 or carbon nitride, yielding alkanes (ethane and propane), whereas electrocatalysis on carbon electrodes produces alkenes (ethylene and propylene). This two-step recycling process of plastics can use sunlight or renewable electricity to convert polyethylene into valuable, easily separable, gaseous platform chemicals.

Chemical Composition and Low-Temperature Fluidity Properties of Jet Fuels

The physicochemical properties of petroleum-derived jet fuels mainly depend on their chemical composition, which can vary from sample to sample as a result of the diversity of the crude diet processed by the refinery. Jet fuels are exposed to very low temperatures both at altitude and on the ground in places subject to extreme climates and must be able to maintain their fluidity at these low temperatures otherwise the flow of fuel to turbine engines will be reduced or even stopped. In this work, an experimental evaluation of the effect of chemical composition on low-temperature fluidity properties of jet fuels (freezing point, crystallization onset temperature and viscosity at −20 °C) was carried out. Initially, a methodology based on gas chromatography coupled to mass spectrometry (GC–MS) was adapted to determine the composition of 70 samples of Jet A1 and Jet A fuels. This methodology allowed quantifying the content, in weight percentage, of five main families of hydrocarbons: paraffinic, naphthenic, aromatic, naphthalene derivatives, and tetralin- and indane-derived compounds. Fuel components were also grouped into 11 classes depending on structural characteristics and the number of carbon atoms in the compound. The latter compositional approach allowed obtaining more precise model regressions for predicting the composition–property dependence and identifying individual components or hydrocarbon classes contributing to increased or decreased property values.

Multivariate statistics for summarizing diesel feeds for flammability attributes using comprehensive two-dimensional gas chromatography.

Comprehensive 2D gas chromatography has been utilized for analyzing complex mixtures of hydrocarbons of diesel feeds. Here, we evaluated 19 diesel feeds for their paraffinic, naphthenic, and aromatic group compositions dictating their flammability properties. Compositional ranges of feeds were as follows: paraffins: 9.6-57.8%, naphthenes: 7.9-38.5%, and aromatics: 10.5-82.3%. Diesel's flammability performance is estimated by thermodynamic conditions and rates of radical formation of hydrocarbon type in actual engine condition, limiting cetane number. However, limitations are overcome by understanding the relative compositional variations of feeds by simple ranking of feeds based on C15-16 compositions. Due to the multidimensional variability of feeds, a principal component analysis was adopted later for its distinguishing capability. Paraffinic, naphthenic, and aromatic group's principal component analysis clustered up feeds based on the higher concentration of individual hydrocarbon group. We explored hierarchical cluster analysis to organize feeds into classes of mixed C9 to C26 paraffin's composition in the diesel range. Further, for discriminating C15-C16 enriched and depleted feeds in total paraffin composition, a row dendrogram with heat map was drawn. The above multivariate methods have led to a fair distinction of nonadditive feed compositions influencing flammability properties by radical formation rate.

Sonication of Petrochemical Industry Wastewaters

The objective of the study was the treatment of the pollutants (dissolved chemical oxygen demand (CODdis), total organic carbon (TOC) and total and individual polycyclic aromatic hydrocarbons (PAH)) present in the petrochemical industry wastewater (PCI) by sonication. The effects of increasing sonication times (0 min, 60 min, 120 and 150 min), sonication temperatures (25oC, 30oC and 60oC), on the CODdis, TOC and (PAH) removal efficiencies were researched at a sonication frequency of 35 kHz and a sonication power of 640. All the PAHs and their metabolites were measured by an gas chromatography (Agilent 6890 NC) equipped with a mass selective detector (Agilent 5973 inert MSD) with a capillary column (HP5-MS, 30 m, 0.25mm, 0.25µm)). The CH4, CO2 and H2 gas analysis, CODdis, TOC and the other pollutants were measured according to Standard Methods. As the sonication time and temperature were increased from 60 to 120 and 150 min, and from 25oC to 30oC and to 60oC, the CODdis, total PAH and TOC yields increased from 80.16% to 92.15%, from 78.37% to 94.23% and from 79.65% to 96.90%, respectively. The PAHs intermediates namely, 1–methylnaphthalene, 9–hydroxyfluorene, 9,10–phenanthrenequione, benzoic acid, 1,2,3–thiadiazole–4–carboxylic acid, naphthalene, p–hydroxybenzoic acid, fluorene, di–hydroxy pyrene, pyrene di–hydrodiol were sonodegraded with yields of 92.11%, 95.23%, 98.42%, 97.34%, 99.44%, 96.30%, 99.36%, 97.17%, 99.63% and 99.98% respectively, after 150 min, at 25oC. The presence of CH4, H2 and CO2 gases during sonication showed that the degradation mechanism of the PAHs is ‘‘pyrolysis”.

Geochemical mapping of a blue carbon zone: Investigation of the influence of riverine input on tidal affected zones in Bull Island

Bull Island (BI) is a coastal sand spit that formed as an unintended consequence of the construction of two walls, built over 200 years ago in Dublin Port, Ireland to alleviate silting of the shipping route. A large lagoon, on the land side of the island was separated in 1964 by the construction of a causeway to produce two separate lagoons that are now impacted by different water sources. Here we investigate the influence of riverine inputs on the two adjacent but unconnected tidal wetland lagoons. The South lagoon (SL) is supplied by tidal water passing through the eutrophic R. Liffey and R. Tolka estuary zones, while the North Lagoon (NL) is supplied by seawater and to a lesser degree, freshwater from the R. Liffey plume. Within each of these zones a clear ecotone exists between the mudflats (MF) and vegetated saltmarshes (SM). We determined the quantity and distributions of bulk geochemical characteristics across BI’s sediments, including total organic carbon (TOC), total nitrogen (TN), metals, and also, 16 individual polyromantic hydrocarbon’s (PAH’s) as an indication of anthropogenic input. Primary focus was placed on studying the blue carbon sediments of the lagoon zones. Significant differences in analytical results showed major influences exerted on sediment geochemistry within each lagoon. This study highlights the ability of a functioning coastal wetland to flourish and sequester elevated levels of carbon, metals and pollutants under the constraints of increasing anthropogenic impact. As the inadvertent result of geo-engineering, BI and its environs is a very important site to investigate the potential of artificially constructed wetlands to act as blue carbon reservoirs.

The Nasonov gland pheromone as a potential source of death cue in Apis cerana

The ability to detect and remove dead adult bees is an essential part of honeybee colony fitness that prevents the spread of pathogens. Fatty acid olfactory cues stimulate undertaking behavior among different social species within Hymenoptera, but the chemicals responsible for the death cue in Apis cerana have not yet been identified. We explored the Nasonov gland as a potential source of these chemicals in A. cerana. Gas chromatography indicated that unlike A. mellifera, the A. cerana Nasonov gland does not contain any volatile terpenes, only fatty acids. As a bioassay, dead honeybees were rinsed free of their individual cuticular hydrocarbons via dichloromethane and two concentrations of oleic acid and a synthetic blend of the Nasonov pheromone in A. cerana were applied to the dummies. Results showed that oleic acid did not stimulate corpse removal in A. cerana. However, the synthetic pheromone blend of A. cerana Nasonov did stimulate removal.

A Comparative Plume Study of DRO, GRO, Benzene, and MTBE: Implications for Risk Management

AbstractGroundwater remediation and no‐further action decision making at petroleum underground storage tank (UST) sites has largely been based on an understanding of plume length, plume stability, and attenuation rates for key hydrocarbon constituents. Regulatory guidance to support and guide such decisions is based in part on plume studies involving individual hydrocarbon constituents, namely benzene and methyl tert‐butyl ether (MTBE). Questions remain regarding whether current guidance is applicable to chemical mixtures such as gasoline range organics (GRO), diesel range organics (DRO), and oxygen containing organic compounds (OCOCs) resulting from hydrocarbon biodegradation. To help address this concern, data from California's GeoTracker database were used to estimate maximum plume lengths, plume stability, and attenuation rates of DRO (which can be used as an analytical surrogate for OCOCs) and GRO relative to benzene and MTBE. The distributions of maximum plume lengths were similar for the four constituents with medians ranging from 27 to 32 m. The fraction of monitoring wells with a decreasing concentration trend ranged from 19% for DRO to 40% for MTBE, while fewer than 7% of the wells had an increasing concentration trend for any of the constituents. Median attenuation rates ranged from 0.10% day−1 for DRO to 0.17% day−1 for MTBE. The results suggest attenuation based risk management is appropriate for DRO and GRO plumes at most petroleum UST sites.

The Paleoclimate Significance of the δ13C Composition of Individual Hydrocarbon Compounds in the Maoming Oil Shales, China

Maoming oil shales are typical low-altitude lacustrine sediments that were deposited during the late Paleogene. The hydrocarbon composition and compound-specific stable carbon isotopic composition (δ13C) of organic matter in the profile samples of the oil shales have been analyzed. The results show that algae and aquatic plants are major parent sources of the organic matter in the oil shales associated with a small portion of terrestrial higher plant input. The δ13C composition of the bulk organic matter and the n-alkanes varies greatly on the profile from −26.9 to −15.8‰ and −31.7 to −16.2‰, respectively. While a good positive correlation among the δ13C composition of individual n-alkanes implies that these n-alkanes were originated from the similar source input. The δ13C composition of n-alkanes on the profile displays a positive excursion trend from the bottom to the top, and this excursion was likely related to the general decreasing trend of the partial pressure of atmospheric CO2 (pCO2) during the late Paleogene. The δ13C composition of the C30-4-methyl steranes ranges from −11.9 to −6.3‰, which is suggestive of Dinoflagellates-related source input. Coincidently, the high abundance C33-botryococcanes were detected in the samples on the top section of the profile and display an extremely positive carbon isotopic composition of −4.5 to −8.4‰, suggesting that the lower partial pressure of atmospheric CO2 had triggered a bicarbonate consumption mechanism for Botryococcus braunii B. Therefore, the δ13C composition of n-alkanes and C33-botryococcanes and their profile variation suggest that a general declining process associated with fluctuation in the partial pressure of atmospheric CO2 is likely the major reason for the rapid climatic changes toward the end of the late Paleogene.

Low temperature autoignition of Jet A and surrogate jet fuel

An experimental study of the low-temperature and low-pressure autoignition of Jet A and surrogate fuels was conducted using the ASTM-E659 standardized test method. Two surrogate fuels (Aachen and JI mixtures), their individual components and two batches (POSF-4658 and POSF-10325) of standardized Jet A were tested using the ASTM-E659 method for a range of fuel concentrations and temperatures. The ignition behaviors were categorized into four distinct ignition modes. The individual hydrocarbon components had a wide range of ignition behaviors and minimum autoignition temperatures (AIT) values depending on the molecular structure. The two Jet A batches showed similar ignition behavior with measured AITs of 229 ±3°C and 225 ±3°C respectively. Both surrogates exhibited similar ignition behavior to Jet A with comparable AITs of 219 ±3.1°C (Aachen) and 228 ±3°C (JI) with the JI mixture proving to be a more suitable surrogate to Jet A in the low-temperature thermal ignition regime.

A predictive model of catalytic cracking: Feedstock-induced changes in gasoline and gas composition

One way to improve and predict unsteady processes of petroleum fuel production is to develop a mathematical model, that considers the feedstock composition. A study of various feedstock deep refining processes is particularly important. In this paper, we present the prediction of the catalytic cracking unit under feedstock base expansion by using oil fractions with a higher boiling point. The zeolite-containing catalyst with ZSM-5/Y ratio = 0.11 was used in this work. A new kinetic model involving the high molecular weight of C13–C40 hydrocarbons, gasoline groups, gas individual hydrocarbons and coke formation reactions was developed. The feed comprehensive studies, the development and application of a mathematical model allow assessing the feasibility of various feedstock types involvement. The impact of four feedstock types on the yield of catalytic cracking products, catalyst deactivation degree, gasoline and gas composition, and octane number were determined. Among the feedstocks under study are West Siberian oil vacuum gas oil, a mixture of Kazakhstan and West Siberian oil, a mixture of vacuum and atmospheric gas oil with residual feedstock (extract, slack waxes, petrolatum, deasphalting agent, raffinate), a mixture of vacuum distillate and residual feedstock (extracts, slack waxes).

New Methods for Atomic-Absorption Determination of Metals in Aviation and Automotive Gasolines

Methods were developed for direct atomic absorption determination of lead and lithium as components of antiknock additives in aviation and automotive gasoline at concentrations in the ranges of 100-1700 (lead) and 2.5/0.25-100 (lithium) mg/dm3. The conditions of atomization of the sample solutions and calibration solutions and elimination of the effect of the matrix of the analyzed samples on the results were achieved by suitable dilution of the samples and by including aliquots of solutions simulating the composition of gasolines prepared from individual high-purity hydrocarbons in the composition of the reference solutions and calibration solutions. The methods are characterized by high precision, are simple to use, and can be recommended for quality control and identification of gasoline.

Study of the Synergetic Effect of Co-Pyrolysis of Lignite and High-Density Polyethylene Aiming to Improve Utilization of Low-Rank Coal.

The mutual impact of low-quality lignite and high-density polyethylene (HDPE) during open system pyrolysis was investigated, aiming to improve utilization of lignite with simultaneous treatment of HDPE waste. Pyrolysis of lignite, HDPE, and their mixture (mass ratio, 1:1) was performed at temperatures 400, 450, 500, 550, and 600 °C. Initial substrates and pyrolysis products were characterized by thermogravimetric analysis (TGA), gas chromatography–mass spectrometry (GC–MS), specific carbon isotope analysis of individual hydrocarbons (δ13C), Rock-Eval pyrolysis, and elemental analysis. The positive synergetic effect during co-pyrolysis of lignite/HDPE mixture was observed at temperatures ≥450 °C, with the greatest being at 500 °C. The highest yield of liquid co-pyrolysis products with a similar composition to that of crude oils is also noticed at 500 °C. The yields of liquid and gaseous products and quality of pyrolytic products obtained by co-pyrolysis of lignite/HDPE mixture are notably improved compared with pyrolysis of lignite alone. On the other hand, data obtained from pyrolysis of HDPE alone indicate that it cannot be concurrent to well-developed catalytic thermal processes for polymer recycling. However, concerning the huge amount of produced HDPE, at least part of this plastic material can be reused for advanced thermal treatment of lignite, particularly in countries where this low-rank coal represents the main source of energy.

Oil and gas seepage offshore Georgia (Black Sea) – Geochemical evidences for a paleogene-neogene hydrocarbon source rock

Numerous hydrocarbon seep sites at the continental shelf, slope, and in the deep water basin are known to feed the Black Sea water reservoir of dissolved methane. In this study, we identified the likely sources of gas and oil that are emitted at four sites located on the continental slope offshore Georgia in the Eastern Black Sea at 830 to 1,140 m water depth – an area with gas seepage only (Batumi seep area) and three areas of coupled gas and oil seepage (Iberia Mound, Colkheti Seep, and Pechori Mound). The geochemistry of bulk parameters, organic fractions and individual hydrocarbon biomarkers in near-surface sediments and of gas/oil expelled from the seafloor was analyzed and jointly interpreted to assign most likely hydrocarbon source rocks in the studied region. Presence of oleanane in shallow oil-impregnated sediments and oil slicks attests that the source rock at all sites is younger than Mid Cretaceous in age. We conclude that hydrocarbons ascending at all the four seepage areas originate from the Eocene Kuma Formation and/or the Oligocene–Lower Miocene Maikop Group, which are considered the principal hydrocarbon sources in the Eastern Black Sea region. Distributions of crude oil biomarkers in shallow sediments suggests moderate to heavy biodegradation. C1/C2+ ratios (10–4,163) along with stable C and H isotopic ratios (δ13C–CH4 ‒46.3 to −53.1.3‰ V-PDB; δ2H–CH4 ‒159 to −178‰ V-SMOW) indicate gas mixtures of oil-associated thermogenic and secondary microbial light hydrocarbons that are discharged from the four seep sites. Light hydrocarbons discharged at the Batumi Seep area are characterized by significant enrichments of methane, but have almost similar δ13C–CH4 values if compared to the other study sites. Such methane enrichments likely result from a comparably higher degree of petroleum degradation and associated formation of secondary microbial methane.

STABILITY OF PHYTOCENOSES IN OIL-PRODUCING REGIONS

The only real way to deal with the consequences of oil and oil products spills is a complex of works, including mechanical or physico-chemical removal of spilled oil products with subsequent purification of the remaining oil in the soil by biological methods using phytoremediation with oil-oxidizing plants. One of the stages of the study of hydrocarbon-oxidizing plants before their introduction into the environment for remediation of contaminated sites is the study of the process of degradation of pollutants in model soil systems. Model experiments on cleaning and restoration of soils after their contamination with oil and oil products by plant biomass were studied. Oil samples from the Tengiz field were taken. During the experiments, the indicator of the total amount of biomass, as well as the oil content in the soil, was controlled. To correctly assess the participation of plant raw materials in the destruction of oil, experiments were carried out using non-sterile soils. Among other plant cultures, the most degrading activity was shown by plant cultures of the genus Fabaceae, which led to an increase in growth in the soil environment by an average of 7 sm in 20 days. This is observed for plants with oil concentrations of 3, 6 and 9 g. The results of physical and chemical analyses of phytoremediation products of crude oil, petroleum products and individual aromatic hydrocarbons can be important in microbiological and chemical studies with geobotanical indicators that allow analyzing the mechanism of action of biomass in the process of phytoremediation in the disposal of oil waste that pollutes the environment. The available data on the effect of petroleum hydrocarbons on plants are very contradictory. The species diversity of plants capable of growing on oil-contaminated soils has not been sufficiently studied. Knowledge of the degree of resistance of plants to hydrocarbon pollution is necessary to address issues related, on the one hand, to the possibility of their cultivation on contaminated soil, and on the other - to use for the restoration of disturbed soil fertility. In connection with the above, it is of great scientific and practical interest to study the effect of various doses of oil on changes in vegetation cover, soil properties and assessment of their phytotoxicity, which together determines the relevance of the stated topic.

Impacts of ionization radiation on the cuticular hydrocarbon profile and mating success of male house crickets (Acheta domesticus)

Purpose Ionizing radiation is well known to have drastic impacts on major life history features including survivorship, growth, fertility, and longevity. What is much less appreciated is how radiation stress can cause changes to more subtle traits, such as those associated with sexual signaling, an underappreciated but vital aspect of insect reproduction. In the House Cricket (Acheta domesticus) cuticular hydrocarbons are vital for sex and species recognition, as well as a possible indicator of stress, making them crucial for successful mating and reproduction. Materials and methods Here, we analyze the impacts of ionizing radiation on the cuticular hydrocarbons of male crickets and its subsequent impacts on mating success. We exposed juvenile (14-day, 4th instar) male crickets to a broad range of radiation doses (2 Gy − 2 Gy). Results We detected significant changes in individual cuticular hydrocarbons across a broad range of doses in mature male crickets using gas-liquid chromatography. Specifically, dose was identified as a significant contributing factor to hydrocarbon increases p < .0001. Mating success was significantly reduced in 12 Gy (p < .0001), 10 Gy (0.0001), and 7 Gy (0.0060) groups compared to non-irradiated controls. Conclusion Insect chemical communication can be species specific, and functionally specialized. Here, we show that radiation can alter the chemical signals used to attract mates in a large bodied insect and this may be a contributing factor to the described reduction in male mating success. Further research should be conducted to further analyze the various modes of communication employed by male crickets to attract mates i.e. acoustic signaling, and how this may also contribute to the reduction in mating success seen in irradiated males.

Effects of crude oil on the biological activity of chernozem soils

The article investigates the effect of crude oil on soil microorganisms and the enzymatic activity of chernozem soils. Experiments were carried out on podzolized medium loamy chernozem in the Samara region using high-sulphur crude oil of medium density. Per 1 kg of soil, 10.00 g (1%), 30.00 g (3%) and 50.00 g (5%) of oil were applied. According to the obtained results, the native soil microbiota contains a wide variety of microorganisms capable of oxidizing both individual hydrocarbons and crude oil in general. Bacteria of the Acinetobacter, Bacillus, Mycobacterium, Pseudomonas and Streptomyces genera, filamentous fungi of the Aspergillus and Penicillium genera, as well as Candida yeast showed the greatest activity in the degradation of both individual hydrocarbons and crude oil in general. The soils freshly polluted with oil demonstrated an increase in the number of bacteria that consume organic forms of nitrogen, actinomycetes, fungi and hydro-carbon-oxidizing microorganisms. In addition, a growing trend in the number of autochthonous microorganisms participating in the mineralization of humic substances was observed. Following 3 months of experiments, a decrease in the number of bacteria consuming organic forms of nitrogen and actinomycetes was revealed. The number of fungi showed the most pronounced decrease upon addition of 3 and 5% of oil, while the number of autochthonous microorganisms participating in the mineralization of humic substances and hydrocarbon-oxidizing microorganisms grew with an increase in the degree of oil pollution. Inhibition of various microorganisms by means of physical or toxic action of hydrocarbons contained in crude oil can cause a decrease in the activity of enzymes present in chernozem soils. Oil hydrocarbons inhibit the activity of polyphenol oxidase, catalase, invertase, phosphatase and lipase present in chernozem soils, although slightly stimulating the peroxidase activity. A decrease in the soil humification coefficient indicates that the oxidation of humic substances prevail over the decomposition of organic aromatic compounds into soil humus components, as well as a decrease in soil fertility as a result of its contamination with crude oil hydrocarbons.