Oil Fractions Research Articles

Assessing the Level of Pollution and Effectiveness of Soil Rehabilitation Technologies in Case of Crude Oil Spills

It was shown that the use of methods of chemical analysis of oil-contaminated soils recommended for environmental control, showed no more than 50% of the mass of oil introduced into the soil, even in freshly contaminated samples. It was found that main errors were associated with the loss of light oil fractions during drainage of contaminated soil samples, incomplete extraction of pollutant oil from soils, ignoring high-molecular polar oil fractions, resinous and asphaltenic fractions when using these methods. A slight modification of the applied preparatory analytical methods was proposed, wich consisted in replacing the cold extraction of contaminated soil with a hot one, followed by additional weighing of the extracted chloroform prior swing absorption to assess the content of oil products, as well as soil samples for extraction at a natural moisture level without air- dry preconditionning. It was concluded that these changes significantly reduce analytical errors and increase the reliability of monitoring soil pollution during crude oil spills, as well as the effectiveness of rehabilitation actions.

Impact of development and irrigation on the soil of the dry steppe zone of Azerbaijan and the classification system

In the given article the research results on change of the morphological – genetic structure of the profile, granulometric composition, distribution of the physical clay on profile, supplement of density, gross composition of soil and silty fraction of the virgin [Grey Cinnamonic] and irrigated grey-brown soil [Irrigated Grey- Cinnamonic] in the arid steppe zone of Azerbaijan have been described depending on their agricultural use and antiquity of irrigation. Dependence of their density supplement of the irrigated grey-brown soil on granulometric composition and antiquity of their irrigation was established. The place of the virgin and irrigated grey-brown soil was defined depending on agricultural use and antiquity of irrigation in the system of the international classification of WRB (2014): virgin saturated gleyey calcareous heavy-loamy grey-brown soil - Duric Gleyic Calcic Kastanozems (Loamic); Long- irrigated grey-brown (irrigationaccumulative) (more than 300 years), powerful gleyey cultivated Long- irrigated calcareous heavy-loamy-Gleyic Petrocalcic Kastanozems (Anthric, Loamic).

Fabrication and characterization of tea seed oil pickering emulsion stabilized synergistically by carboxymethylcellulose and β-cyclodextrin

Carboxymethyl cellulose and β-cyclodextrin stabilized water-wrapped tea seed oil Pickering emulsion was prepared using the high-speed shearing method. The particle size test and microstructure observation showed that the average particle size of the emulsion droplet decreased while the apparent viscosity, viscoelasticity, and stability increased with the increase in the concentration of carboxymethyl cellulose, β-cyclodextrin, and oil fraction. The droplet size of the emulsion increased slightly after heating from 50 °C to 90 °C, and the thermal stability of the emulsion increased after 50 °C treatment. pH exhibited little effect on emulsion stability. Carboxymethyl cellulose enhanced the adsorption of cyclodextrin colloidal particles on the water-oil interface via non-covalent interaction, steric hindrance, and drainage, which improved the viscosity of the emulsion. Therefore, it can be seen that the combination of carboxymethyl cellulose and β-cyclodextrin can significantly increased the stability of emulsions.

GROWTH PERFORMANCE AND SELECTED BIOCHEMICAL INDICES ASSESSMENT IN THE SERUM AND LIVER OF CLARIAS GARIEPINUS JUVENILES EXPOSED TO VARYING CONCENTRATIONS OF WATER SOLUBLE FRACTION OF CRUDE OIL

The effect of varying concentrations (0, 0.25, 0.05 and 1.0% v/v) of water soluble fraction (WSF) of crude oil on the growth performance and biochemical changes in the serum and liver of 144 Clarias gariepinus Juveniles stocked into 12 glass aquaria at the rate of 12 fish per tank in triplicate for 90 days was assessed. The growth performance indices of the fish juvenile over the 90 days of toxic exposure revealed that the mean weight gained, specific growth rate, and total feed intake of the fish specimen decreases with increase concentration of the WSF of crude oil. However, 10% and 20% mortality were recorded in the fish exposed to 0.5% and 1.0% WSF of crude oil respectively. The activity of ALT and AST in the serum of the fish were significantly higher (p<0.05) with the increased concentration of WSF of crude oil while the ALT and AST activity of the liver of the fish juveniles irrespective of the added concentration of WSF of crude oil showed no significant differences (p>0.05). The study concluded that WSF of crude oil had adverse effects on the growth performance, blood serum and liver activities in C. gariepinus juveniles.

Temporal dynamics of density separated soil organic carbon pools as revealed by δ13C changes under 17 years of straw return

Straw return is widely recommended as an effective measure to increase the amount of soil organic carbon (SOC) and improve soil fertility in agroecosystems. However, the temporal dynamics of the original and newly derived SOC during long-term straw return remain uncertain. This study aimed to (i) determine the temporal dynamics of original and newly derived SOC in various soil organic matter (SOM) fractions during cultivation and (ii) evaluate the effect of continuous straw return on the contents of original and newly derived SOC. These aims were achieved by analyzing topsoil samples (0–20 cm) in a 17-year field experiment using a continuous maize (Zea mays L.) cropping system. Three fertilizer treatments were tested: no fertilizer (NF), mineral fertilizer (NPK), and mineral fertilizer with straw return (NPKS). The SOC was physically separated into three density fractions: the free light fraction (fLFOC), occluded light fraction (oLFOC), and heavy fraction (HFOC), and their δ13C values were determined. The original and newly derived SOC of each fraction and the rate of conversion of exogenous C inputs were evaluated. The SOC content in the bulk soil and C fractions generally increased continually with cultivation time in the NPKS, indicating that the soil had not reached maximum C sequestration. NPKS significantly increased the C contents of fLFOC, oLFOC, and HFOC by 38.6%, 43.0%, and 11.6%, respectively, relative to the initial soil after the 17-year experiment. The newly derived SOC content was significantly higher in NPKS than in NF and NPK, and the rate of conversion of exogenous C inputs to SOC was the lowest in NPKS. The annual rate of loss of original SOC in NPKS was lowest for the light fractions (fLFOC and oLFOC) and highest for HFOC, implying that the return of straw moderated the mineralization of original SOC in the light fractions but increased the decomposition of original SOC in the heavy fraction via the priming effect (PE). The average rate of conversion of exogenous C inputs remained the highest in HFOC (23.5%), lowest in oLFOC (0.6%), and intermediate in fLFOC (4.1%) throughout the study. Thus, the stable HFOC pool retained more straw C, despite the stronger PE. Our results demonstrated that long-term straw return continuously increased the proportion of new SOC in the bulk soil and density fractions and increased the decomposition of the original SOC in the stable SOC fractions. These findings provide further detailed insights into the mechanisms of SOC stabilization in agricultural soils.

Valorization of water hyacinth biomass for bio-oil production using a novel combinatorial approach of UV/H2O2 advanced oxidation process pretreatment and catalytic fast pyrolysis over ZSM-5

In order to improve bio-oil quality from water hyacinth biomass, a novel UV/H2O2 advanced oxidation process pretreatment is implemented coupled with shape-selective catalytic fast pyrolysis over ZSM-5. Characterization results demonstrate that UV/H2O2 pretreatment is an effective method to remove oxygen in biomass feed, and cellulose content can be enriched by delignification. Py-GC/MS results show that UV/H2O2 pretreatment can favor oil fraction production, and the combinatorial use of ZSM-5 catalyst promotes the formation of hydrocarbons and monocyclic aromatic hydrocarbons, while the contents of acids and phenols in oil fraction decay dramatically. Finally, response surface analysis is conducted to investigate the two pretreatment experimental variables, namely, initial H2O2 concentration and pretreatment time, on the relative contents of certain vital chemicals in oil fraction. The regression equations between the compound contents in bio-oil and the two experimental variables are established, and the best-fitting models are quadratic regression equations.

Quantifying phosphorus fertilizer distribution and the contribution of fertilizer and soil legacy phosphorus to phosphorus uptake by maize – A 32P‐labelling study

AbstractThe availability of phosphorus (P) fertilizer applied to soil can diminish rapidly because of the complex soil P immobilization processes. However, the quantitative distribution of fertilizer P in the soil P fractions is not fully understood. Here, two experiments were conducted in a greenhouse using 32P‐labelled KH2PO4 to (i) quantify the distribution of P fertilizer in soil fractions, microorganisms and maize shoots grown in contrasting soils; (ii) characterize the effect of planting maize on soil P fractions and (iii) determine the amount of plant P derived from fertilizer vs. soil. Depending on the soil type, 74.1%–84.1% of the labelled P was retained in the soil, 11.4%–14.5% was found in maize shoots and 0.7%–4.5% was present in microorganisms. Distribution of applied P in the soil P fractions was dependent on soil type, with most P present as NaOH‐Pi and residual‐P in the Red soil, and as HCl‐P in the Fluvo‐aquic soil. Root‐mediated processes were involved in mobilisation of residual‐P in all three soils, with significant depletion of NaOH‐Pi in the Red soil, NaOH‐Pi and HCl‐P in the Black soil, and HCl‐P in the Fluvo‐aquic soil. The plant P derived from fertilizer and soil increased with increasing P addition rates in all three soils. In the soils with low‐P availability, fertilizer contributed more P to plants than soil, whereas in the initially high‐P soil, the opposite occurred. In conclusion, the partitioning of fertilizer P to various soil P fractions is dependent on the soil type, and the contribution of P derived from fertilizer to maize P uptake was related inversely to the soil legacy P.

Spawning time in adult polar cod (Boreogadus saida) altered by crude oil exposure, independent of food availability

ABSTRACT Fish early life stages are well known for their sensitivity to crude oil exposure. However, the effect of crude oil exposure on adults and their gametes during their spawning period is not well studied. Polar cod, a key arctic fish, may be at risk for crude oil exposure during this potentially sensitive life stage. Additionally, this species experiences lower food availability during their spawning season, with unknown combined consequences. In the present study, wild-caught polar cod were exposed to decreasing levels of a water-soluble fraction (WSF) of crude oil or control conditions and fed either at a low or high feed ration to assess the combined effect of both stressors. Samples were taken during late gonadal development, during active spawning (spawning window), and in the post-spawning period. Histology analysis of gonads from fish sampled during the spawning window showed that oil-exposed polar cod were more likely to have spawned compared to controls. Oil-exposed females had 947 differentially regulated hepatic genes, and their eggs had a higher polycyclic aromatic hydrocarbon body burden compared to controls. Feed ration did not consistently affect polar cod’s response to oil exposure for the endpoints measured, however, did alone result in decreases in some sperm motility parameters. These results suggest that polar cod’s spawning period is a sensitive life event to crude oil exposure, while feed limitation may play a minor role for this supposedly capital breeder. The effects of adult exposure to crude oil on gamete quality and the next generation warrant further investigation.

The effect of enzymatic interesterification on the high oleic-high stearic sunflower oil fractionation and the physico-chemical properties of stearins

Oil fractionation processes typically involve the crystallization of the most saturated triacylglycerols to facilitate the separation of the liquid phase. However, the fractionation of new high stearic oils derived from sunflower (HOHS) is not as efficient as that of tropical fats. In the present work we studied the effect of enzymatic inter esterification (EIE) on the HOHS sunflower oil fractionation. EIE altered the properties and melting point of the HOHS oil, so it eased fractionation allowing operation at lower temperatures (8 °C). These fractionations produced stearins with high saturated fatty acid contents at higher yields than the non-EIE oil (28.3% vs 18.7%). The melting profile of the stearins were also characterized. EIE stearins displayed broader melting profiles with higher crystallization onsets (from 26.3 °C to 34 °C). Fractionations proved to be reproducible at pilot plant scale. The resulting stearins exhibited a solid content of 30% at 20 °C and displayed solidification curves similar to palm-based filling fats. The results indicate that changes in fatty acid distribution in the TAG backbone critically affect TAG crystallization, which was faster and more reproducible, not requiring prior dewaxing and seeding. Moreover, the fractionation products differed, yielding stearins with higher levels of solids.

POZZOLANIC MATERIALS FOR STABILIZATION /SOLIDIFICATION OF SOIL CONTAMINATED BY HEAVY METALS - A REVIEW

Soil contamination with heavy metals significantly threatens human health and the ecosystem. Due to the complexity of heavy metal interactions in soils, the mobility, bioavailability, and toxicity of metals in the soil fractions are impacted by several parameters. These parameters include the qualities of both the metal and the soil. However, several remedial methods have been used in immobilization techniques. One of the best techniques is the Stabilization/Solidification(S/S) approach, which is often used to remediate contaminated sites and combines contaminants with binders to reduce the quantity of contaminant leachability through soil matrix and groundwater pollution. As well as to minimize the risks to human health and the environment, alter the metals in the soil to make them less soluble, toxic, or bioavailability. Stabilization aims to change the contaminated material's physical and chemical characteristics to decrease its chemical reactivity or solubility. In contrast, solidification aims to turn contaminants into solids that can be handled easily and contain a few dangerous materials. This review's primary goal is to examine the pozzolanic materials used in the Stabilization/Solidification process and their potential for remediating soil contamination, mainly where heavy metals are present.

Safety and efficacy of feed additives consisting of essential oils derived from the flower buds or the leaves of Syzygium aromaticum (L.) Merr. & L.M. Perry (clove bud oil and clove leaf oils) for all animal species (FEFANA asbl).

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of essential oils from the flower buds or the leaves of Syzygium aromaticum (L.) Merr. & L.M. Perry: clove bud oil, clove leaf oil and a β-caryophyllene-rich fraction of clove leaf oil (CCL oil), when used as sensory additives in feed and water for drinking for all animal species. Clove oils contain methyleugenol (up to 0.13%). The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concluded that the use of clove oils was of low concern for long-living and reproductive animals and of no concern for target species for fattening at the following concentrations in complete feed: 25-50 mg/kg for clove bud oil, 28-100 mg/kg for clove leaf oil and 20 mg/kg for CCL oil. The FEEDAP Panel considered that the use in water for drinking alone or in conjunction with use in feed should not exceed the daily amount that is considered of low or no concern when consumed via feed alone. No concerns for consumers were identified following the use of clove oils up to the highest safe level in feed. The additives under assessment should be considered as irritant to skin and eyes and the respiratory tract and as skin sensitisers. When handling the essential oils, exposure of unprotected users to methyleugenol may occur. Therefore, to reduce the risk, the exposure of the users should be minimised. The use of clove oils at the proposed use level in feed was not expected to pose a risk for the environment. Since clove bud oil and clove leaf oil are recognised to flavour food and their function in feed would be essentially the same, no demonstration of efficacy was considered necessary.

Assessing Weathering, Pedogenesis, and Silt Generation in Granitoid‐Hosted Soils From Contrasting Hydroclimates

AbstractThe origin and production of silt are key factors in the formation of loess deposits. Although many processes can potentially lead to silt generation, few are known to produce silt in the volumes and particle‐size modes required to form geologically significant loess deposits. Here, we investigate the hypothesis that soil‐associated weathering in tropical and Mediterranean climates can generate abundant in situ silt, and therefore contribute significantly to loess formation throughout geologic time. We utilize granulometric and geochemical data from two granitoid‐hosted soils formed in Puerto Rico (hot‐humid climate) and Southern California (hot‐arid climate) to discern whether the silt + clay fraction (<62.5 μm) is generated from bedrock weathering (autochthonous) or sourced from eolian contributions (allochthonous). Our study demonstrates that the PR soil contains abundant (up to 72%) silt‐ and clay‐sized particles compared to the Southern California soil (<6%). However, the silt fraction of the PR soil is at least partially derived from eolian inputs, and the silt fraction of the Southern California soil is geochemically indistinguishable from allochthonous dust sources. Furthermore, while intense chemical weathering in PR can produce abundant fines, the majority are significantly finer (average mode ∼15 μm) than the modes of most “typical” loess deposits (modes more than 20–30 μm). In contrast, weathering in the Southern California soil produces volumetrically sparse silt. Hence, weathering processes within these two profiles, representing hot‐humid and hot‐dry climates, appear to be ineffectual for producing the volume and size distributions of silt needed to generate significant loess deposits.

Assessment of Greenhouse Gas Emissions and Carbon Reserves with Zero Processing of Chernozem in the Conditions of the Forest-Steppe Zone of the Middle Volga Region

The transition from conventional soil treatment technology to zero treatment technology contributes to an increase in carbon sequestration (Sorg) in the form of carbon dioxide (CO2) from the atmosphere into the soil and, as a result, a reduction in the adverse effects of the greenhouse effect on the ecological state of the environment. The effectiveness of the application of zero tillage is to a greater or lesser extent due to specific agro-climatic conditions, crop rotation systems, fertilizers and plant protection, soil quality and stability. The influence of zero tillage on the dynamics of sorghum reserves and greenhouse gas emissions (CO2, N2O, CH4) in the agro-climatic conditions of crop production (LLC “Orlovka AIC”, Samara region) was investigated. The study was conducted on agrochernozem heavy loam in September–November 2021 in conditions of an abnormally arid growing season and high summer temperatures. On plots with zero tillage, plant residues were received: 268–1720 kg С/ha, 3–66 kg N, 0.2–7.7 kg P and 12–44 kg K/ha. Based on the results obtained, recommendations are proposed for further improving the efficiency of zero tillage technology due, firstly, to reducing its adverse effect on the density of soil composition, and, secondly, taking into account the influence of underlying parent rocks and relief on water erosion of soil and redistribution of granulometric fractions of soil in the agricultural landscape, which will allow using this technology according to principles of adaptive landscape farming.

The structure of forest vegetation on industrial landfills of different ages

AbstractThe purpose of the research is to describe plant community formation on the quarry surfaces to determine a path for optimal revegetation. To achieve the goal, the studies determined soil pH, the content of skeletal fraction, basal respiration, and performed the acidimetric assessment of CO2. The research program aimed to investigate the peculiarities of plant communities' formation in areas with different degrees of revitalization and investigate the influence of soil cover on plant associations. Results showed that the average basal soil respiration rate on the quarry was extremely low (about 0.3 mg CO2/g of soil/h). The CO2 content in the carbonate ranged from 0.07% to 0.7%, with the higher figures observed in older Kuzbass rather than Mosbass and Sokolovsky quarries. An analysis of soil samples from three quarries revealed four plant groups at sites associated with the prevalence of specific fractions, such as gravel, sand, silt, and stony soil. Given that Kuzbass is the oldest open‐pit mine, forest vegetation species dominate here in the surveyed areas (>40%), and this feature is typical of gravel soils. The dominant species present on the gravel substrate were downy birch (Betula pubescens), common hornbeam (Carpinus betulus), European oak (Quercus robur), Siberian spruce (Picea obovata), common juniper (Juniperus communis), Siberian larch (Larix sibirica), common pine (Pinus), and Siberian fir (Abies sibirica). Mosbass is also characterized by a diversity of similar species, though work on mineral mining there ended in 2009, more recently than in other sites. Stony and sandy soil fractions predominated in the Sokolovsky quarry, although other studied substrates were also present.

INITIATION OF THE LIQUID-PHASE HYDROCARBON OXIDATION REACTIONS BY HIGH-MOLECULAR OIL FRACTIONS

High-molecular oil fractions exhibiting the initiating effect, nontypical for these oil objects, on the model reaction of cumene radical oxidation were investigated by means of microcalorimetry. It is shown for some objects that the initiators appear in the high-molecular fractions of oil in the course of their isolation from native oils by n-hydrocarbons. An insignificant correlation is established between the content of nickel, vanadium, and vanadylporphyrins and initiating activity. The initiators have been found in freshly isolated ‘acid resin’ fractions, which lose their initiating ability during storage due to chemical condensation processes. This method may be considered as a test for the content of inhibitors or initiators of radical oxidation in oil objects.

Taxonomy and genesis of soils in contrasting ecosystems of Southern Western Ghats, India

Clay minerals formed during soil formation are imprints of ecosystem functioning and pedogenic processes in landscapes. The study evaluated the variations in taxonomy, soil weathering and pedogenic changes in contrasting forest soils in the Southern Western Ghats, India. Three different forest systems with comparable soil-forming factors vis-a-vis evergreen, moist deciduous and a man-made system (rubber plantation) were evaluated for physical, chemical, morphological, and pedogenic characteristics of the related soils. Soil profiles were dug up to 1.50 m in the selected ecosystems and horizon-wise soil samples were collected. All the pedons were classified in the soil order of Ultisols and subclassified as Ustic Palehumult (evergreen forest), Ustic Haplohumult (moist deciduous forest) and Typic Haplustult (rubber plantation), respectively. The soil pH was found to be acidic in all the ecosystems ranging from 4.6 to 5.8. Chlorite, hydroxyl interlayered vermiculite (HIV), mica, kaolinite, feldspars, gibbsite and quartz dominated the mineral assemblages in the clay fractions of soils of natural forest systems. The losses of SiO2 in the non-clay fraction and corresponding enrichment of the component in the clay-sized fraction in all horizons indicated an active continuous weathering process in all the systems of this region. Clay accumulation by way of formation and translocation was highest in the lower horizons of the soils of evergreen (Bt2 at a depth range of 28–57 cm) and moist deciduous (Bt3C at a depth range of 23–150 cm) forest, whereas it was highest at Bt1 at a depth range of 15–28 cm in the plantation soil. The depth variations in the clay formations in natural and manmade forest systems provide insights into ecosystems regulated profile development under natural and man-made systems in the humid tropics, a vital information gap hitherto in soil pedogenesis of the humid tropics. Such pedogenic assessments along with the factors responsible for such modifications would provide important inputs in developing soil health management strategies in the humid tropics.

Substrate-independent expression of key functional genes in Cycloclasticus pugetii strain PS-1 limits their use as markers for PAH biodegradation.

Microbial degradation of petroleum hydrocarbons is a crucial process for the clean-up of oil-contaminated environments. Cycloclasticus spp. are well-known polycyclic aromatic hydrocarbon (PAH) degraders that possess PAH-degradation marker genes including rhd3α, rhd2α, and pahE. However, it remains unknown if the expression of these genes can serve as an indicator for active PAH degradation. Here, we determined transcript-to-gene (TtG) ratios with (reverse transcription) qPCR in cultures of Cycloclasticus pugetii strain PS-1 grown with naphthalene, phenanthrene, a mixture of these PAHs, or alternate substrates (i.e., no PAHs). Mean TtG ratios of 1.99 × 10-2, 1.80 × 10-3, and 3.20 × 10-3 for rhd3α, rhd2α, and pahE, respectively, were measured in the presence or absence of PAHs. The TtG values suggested that marker-gene expression is independent of PAH degradation. Measurement of TtG ratios in Arctic seawater microcosms amended with water-accommodated crude oil fractions, and incubated under in situ temperature conditions (i.e., 1.5°C), only detected Cycloclasticus spp. rhd2α genes and transcripts (mean TtG ratio of 4.15 × 10-1). The other marker genes-rhd3α and pahE-were not detected, suggesting that not all Cycloclasticus spp. carry these genes and a broader yet-to-be-identified repertoire of PAH-degradation genes exists. The results indicate that the expression of PAH marker genes may not correlate with PAH-degradation activity, and transcription data should be interpreted cautiously.

Fabrication and Characterization of Novel Food-Grade Bigels Based on Interfacial and Bulk Stabilization.

Novel food-grade bigels were fabricated using zein nanoparticles for interfacial stabilization and non-surfactant gelators (beeswax and tapioca) for bulk stabilization. The present study demonstrated the importance of interfacial stability for biphasic gels and sheds light on the roles of the gelation mechanism and the oil/water ratio of a bigel on its microstructure, physical properties, and digestion behaviors. The results indicated that it is not an easy task to realize homogenization and subsequent gelation in beeswax-tapioca biphasic systems, as no amphiphilic components existed. However, applying the binding of zein nanoparticles at the oil-water interface allowed us to produce a homogeneous and stable bigel (oil fraction reach 40%), which exhibited enhanced structural and functional properties. Oleogel structures play a crucial role in determining the deformation response of bigel systems. As the oil content increased, the mechanical strength and elastic properties of bigels were enhanced. In the meantime, clear bigel-type transitions were observed. In addition, the fabricated bigels were shown to be beneficial for delayed digestion, and the lowest degree of lipolysis could be found in bigel with 50% oleogel.

Modeling weathering processes of spilled oil on the sea surface based on dynamic Bayesian network

Oil spills pose a serious threat to the ecological environment and human health. When the spilled oil enters seawater, oil weathering processes like evaporation, emulsification, biodegradation, photooxidation and dissolution will occur. These processes have high uncertainty and directly affect the spatial distribution and fate of oil spills. This paper presents a stochastic modeling method for weathering process of spilled oil on the sea surface based on Dynamic Bayesian Network (DBN). The physical equations of evaporation, emulsification, biodegradation, photooxidation and dissolution are converted into DBN, and then all the individual DBNs are integrated to obtain the entire DBN of the oil weathering process. The developed DBN could intuitively and graphically express the logical relations and conditional probabilities among physical variables. This method is helpful to find out the influencing mechanism of multi-random variables on the oil weathering process. The proposed method is applied to one type of light oil that is spilled on the sea surface of the Bohai Sea. Based on the developed DBN model, the oil weathering process in the first 18 h are studied by quantitative analysis. Through sensitivity analysis, it shows that the photooxidation and dissolution have greater impact on the heavy oil fraction than biodegradation. For oil-water mixture, it is greatly affected by evaporation in the first few hours, but emulsification becomes the leading weathering process in the 18th hour. The effects of dissolution are low, but higher than biodegradation and photooxidation. The key parameters affecting each oil weathering process are determined. Uncertainty analysis is carried out to reveal the possible upper and lower limit values of some physical quantities caused by the weathering process.

State estimation approach to dual-modal imaging of two-phase flow based on electromagnetic flow tomography and electrical tomography

Monitoring, control and design of industrial processes involving multiphase flows often call for analysis of data from multiple sensors which give information on different quantities of the flowing materials. An example of such case is the problem of monitoring the flow of oil–water mixture: the phase fractions of oil and water, their velocities and volumetric flow rates cannot be retrieved from measurements given by a single sensing/imaging modality. For this reason, multi-modal tomographic imaging systems have been developed. In multi-phase flows, the quantities retrieved from different tomographic instruments are often interconnected—for example, the evolutions of the phase fractions depend on their velocities and vice versa. However, the analysis of data from different tomographic modalities is usually done separately—without taking into account physics that link the quantities of interest. In this paper, we propose a novel approach to image reconstruction in dual-modal tomography of multiphase flows. The governing idea is to combine the two modalities via Bayesian state estimation, that is, we write models that approximate connections between different quantities involved in the process and use sequential measurements from both modalities to jointly estimate these temporally evolving quantities. As an example case, we consider a dual-modal system comprising the electromagnetic flow tomography (EMFT) and electrical tomography (ET). While the EMFT is sensitive to the velocity field but also depends on the phase fractions of fluids, ET measurements are directly linked to phase fractions only. We study the performance of state estimation in EMFT-ET tomography with a set of numerical simulations. The results demonstrate that it outperforms the conventional stationary reconstruction approach, and also provides means for uncertainty quantification in multiphase flow imaging.