Development of novel kinetic model based on microbiome and biochar for in-situ remediation of total petroleum hydrocarbons (TPHs) contaminated soil.

A novel kinetic model has been developed to explain the degradation of total petroleum hydrocarbons. Microbiome engineered biochar amendment may result in a synergistic impact on degradation of total petroleum hydrocarbons (TPHs). Therefore, the present study analyzed the potential of hydrocarbon-degrading bacteria A designated as Aeromonas hydrophila YL17 and B as Shewanella putrefaciens Pdp11 morphological characterized as rod shaped, anaerobic and gram-negative immobilized on biochar, and the degradation efficiency was measured by gravimetric analysis and gas chromatography-mass spectrometry (GC-MS). Whole genome sequencing of both strains revealed the existence of genes responsible for hydrocarbon degradation. In 60 days remediation setup, the treatment consisting of immobilization of both strains on biochar proved more efficient with less half-life and better biodegradation potentials compared to biochar without strains for decreasing the content of TPHs and n-alkanes (C12-C18). Enzymatic content and microbiological respiration showed that biochar acted as a soil fertilizer and carbon reservoir and enhanced microbial activities. The removal efficiency of hydrocarbons was found to be a maximum of 67% in soil samples treated with biochar immobilized with both strains (A + B), followed by biochar immobilized with strain B 34%, biochar immobilized with strain A 29% and with biochar 24%, respectively. A 39%, 36%, and 41% increase was observed in fluorescein diacetate (FDA) hydrolysis, polyphenol oxidase and dehydrogenase activities in immobilized biochar with both strains as compared to control and individual treatment of biochar and strains. An increase of 35% was observed in the respiration rate with the immobilization of both strains on biochar. While a maximum colony forming unit (CFU/g) was found 9.25 with immobilization of both strains on biochar at 40 days of remediation. The degradation efficiency was due to synergistic effect of both biochar and bacteria based amendment on the soil enzymatic activity and microbial respiration.

Paleo-biodegradation and hydrocarbon mixing in a major hybrid petroleum reservoir.

Some of the parental material for hydrocarbons produced from low-permeability reservoirs in Western Canada corresponds to thermal products from biodegraded oil. This has been proved by the occurrence of framboidal pyrite, which is often formed during microbial sulfate reduction (MSR). In addition, the identified pyrite framboids are associated with the presence of phosphorus (P). Phosphorus (as phosphate) is a key nutrient and energy carrier for sulfate-reducing bacteria. The pyrite-P assemblage occurs embedded in solid bitumen (thermal residue), which confirms that migrated hydrocarbons provided the environment for microbial growth. Molecular products of severe biodegradation such as 17-nortricyclic terpanes were also detected. Biodegradation effects have been masked not only by thermal degradation of biodegraded oil during maximum burial, but also due to hydrocarbon mixing with late gas-condensate charges. Suitable conditions for biodegradation (< 80 °C, basin uplift) occurred during the Early Cretaceous. The confirmation of paleo-biodegradation means that there was a significant hydrocarbon loss that we have not accounted for. Likewise, MSR and Early Cretaceous seawater sulfate might have played an important role in the generation of the hydrogen sulfide (H2S) detected today.

Toxicity and human health assessment of an alcohol-to-jet (ATJ) synthetic kerosene developed under an international agreement with Sweden.

Alcohol-to-jet (ATJ) Synthetic Kerosene with Aromatics (SKA) fuels are produced by dehydration and refining of alcohol feed stocks. ATJ SKA fuel known as SB-8 was developed by Swedish Biofuels as a cooperative agreement between Sweden and AFRL/RQTF. SB-8 including standard additives was tested in a 90-day toxicity study with male and female Fischer 344 rats exposed to 0, 200, 700, or 2000 mg/m3 fuel in an aerosol/vapor mixture for 6 hr/day, 5 days/week. Aerosols represented 0.04 and 0.84% average fuel concentration in 700 or 2000 mg/m3 exposure groups. Examination of vaginal cytology and sperm parameters found no marked changes in reproductive health. Neurobehavioral effects were increased rearing activity (motor activity) and significantly decreased grooming (functional observational battery) in 2000 mg/m3 female rats. Hematological changes were limited to elevated platelet counts in 2000 mg/m3 exposed males. Minimal focal alveolar epithelial hyperplasia with increased number of alveolar macrophages was noted in some 2000 mg/m3 males and one female rat. Additional rats tested for genotoxicity by micronucleus (MN) formation did not detect bone marrow cell toxicity or alterations in number of MN; SB-8 was not clastogenic. Inhalation results were similar to effects reported for JP-8. Both JP-8 and SB fuels were moderately irritating under occlusive wrapped conditions but slightly irritating under semi-occlusion. Exposure to SB-8, alone or as 50:50 blend with petroleum-derived JP-8, is not likely to enhance adverse human health risks in the military workplace.

Levels and sources of hydrocarbons in the Patos Lagoon estuary and Cassino Beach mud bank (South Atlantic, Brazil): evidence of transference between environments.

This study assessed the concentrations and sources of natural and anthropogenic aliphatic (AHs) and polycyclic aromatic hydrocarbons (PAHs) in superficial sediments collected along the Patos Lagoon estuary and in sediment cores obtained from the Cassino Beach mud bank. Levels and distribution of n-alkanes indicate terrestrial sources, overlapping with a low amount of petrogenic hydrocarbons (heavy oils). Unresolved complex mixture (UCM) was observed in all samples. On the other hand, the distribution of PAHs in the sediments showed a predominance of pyrolytic over petrogenic sources. In general, hydrocarbons (HCs) contamination in the Patos Lagoon estuary and its adjacent coastal area can be considered low, except for sites near urban or industrial effluents, where moderate to high levels of contamination were found. Concentrations of hydrocarbons were homogeneous throughout the sediment cores, suggesting that mixing processes may have occurred along the layers or that HCs inputs to the mud banks were uniform during the studied deposition period. In addition, the levels and profile of HCs in the coastal sediments were similar to those observed in the estuary. Moreover, the frequent remobilization of sediments from the mud bank towards Cassino beach does not seem to pose any threats to the local biota or beach users since the levels of contamination were relatively low and below the threshold limits of sediment quality guidelines.

Environmental risk assessment of petrogenic hydrocarbon spills in mangrove ecosystems: the Tumaco case study as a baseline, Colombian Pacific.

Petrogenic hydrocarbon spills (PHS) are harmful to mangrove ecosystems along tropical coastlines in the short and long term. The aim of this study was to assess the environmental risk of recurrent PHS on mangrove ecosystems in Tumaco municipality, Colombian Pacific. Mangrove characteristics and management aspects led to subdividing the study area into 11 units-of-analysis (UAs) for which threats, vulnerability, potential impacts, and risks were assessed based on environmental factors and the formulation and use of indicators in a rating scale with five categories, which are very low, low, moderate, high, and very high. The results showed that all UAs are highly (64%; 15,525 ha) or moderately (36%; 4,464 ha) threatened by PHS, highly (45%; 13,478 ha) or moderately (55%; 6,511 ha) vulnerable to this kind of pollution, and susceptible to high (73%; 17,075 ha) or moderate (27%; 2,914 ha) potential impacts. The environmental risk was high in 73% (17,075 ha) of the UAs, indicating likely irreversible damage to mangrove ecosystems by PHS, thus pointing to the need of urgent intervention by responsible authorities to ease their recovery and conservation. The methodology and results of this study become technical inputs that serve for environmental control and monitoring, which can be incorporated into contingency and risk management plans.

Conversion of Polyethylene to High-Yield Fuel Oil at Low Temperatures and Atmospheric Initial Pressure.

The transformation of waste plastics into fuels via energy-efficient and low-cost pyrolysis could incentivize better waste plastic management. Here, we report pressure-induced phase transitions in polyethylene, which continue to heat up without additional heat sources, prompting the thermal cracking of plastics into premium fuel products. When the nitrogen initial pressure is increased from 2 to 21 bar, a monotonically increasing peak temperature is observed (from 428.1 °C to 476.7 °C). At 21 bar pressure under different atmosphere conditions, the temperature change driven by high-pressure helium is lower than that driven by nitrogen or argon, indicating that phase transition is related to the interaction between long-chain hydrocarbons and intercalated high-pressure medium layers. In view of the high cost of high-pressure inert gases, the promotion or inhibition effect of low-boiling hydrocarbons (transitioning into the gaseous state with increasing temperature) on phase transition is explored, and a series of light components are used as phase transition initiators to replace high-pressure inert gases to experiment. The reason that the quantitative conversion of polyethylene to high-quality fuel products is realized through the addition of 1-hexene at a set temperature of 340 °C and the initial atmospheric pressure. This discovery provides a method for recycling plastics by low energy pyrolysis. In addition, we envisage recovering some of the light components after plastic pyrolysis as phase change initiators for the next batch of the process. This method is able to reduce the cost of light hydrocarbons or high-pressure gas insertion, reduce heat input, and improve material and energy utilization.

Solvent Extraction for Separation of Indonesian Oil Sands.

Based on the examination of the basic properties, the solvent extraction process (SEP) was applied with high efficiency in the extraction of bitumen from Indonesian oil sands. To separate the oil sands, different organic solvents were first screened, and the extraction effects were analyzed to select a suitable solvent. Then, the effects of operating conditions on the extraction rate of bitumen were investigated. Finally, the compositions and structures of the bitumen obtained under suitable conditions were analyzed. The results showed that the Indonesian oil sands were oil-wet oil sands with a bitumen content of 24.93%, containing a large number of asphaltenes and resins with high polarity and complex structures. The separation performance was affected by different organic solvents and operating conditions. It was shown that the closer the structure and polarity of the selected solvent is to the solute, the better the extraction effect. The extraction rate of bitumen reached 18.55% when toluene was used as the extraction solvent under the operating conditions of V (solvent):m (oil sands) 3:1, temperature 40 °C, stirring velocity 300 r/min, time 30 min. The method could also be applied to the separation of other oil-wet oil sands. The compositions and structures of bitumen can guide the separation and comprehensive use of industrial oil sands.

Enhanced crude oil degradation by remodeling of crude oil-contaminated soil microbial community structure using sodium alginate/graphene oxide/Bacillus C5 immobilized pellets.

Bioaugmentation (BA) of oil-contaminated soil by immobilized microorganisms is considered to be a promising technology. However, available high-efficiency microbial agents remain very limited. Therefore, we prepared a SA/GO/C5 immobilized gel pellets by embedding the highly efficient crude oil degrading bacteria Bacillus C5 in the SA/GO composite material. The optimum preparation conditions of SA/GO/C5 immobilized gel pellets were: SA 3.0%, GO 25.0 µg/mL, embedding amount of C5 6%, water bath temperature of 50°C, CaCl2 solution concentration 3% and cross-linking time 20 h. BA experiments were carried out on crude oil contaminated soil to explore the removal effect of SA/GO/C5 immobilized pellets. The results showed that the SA/GO/C5 pellets exhibited excellent mechanical strength and specific surface area, which facilitated the attachment and growth of the Bacillus C5. Compared with free bacteria C5, the addition of SA/GO/C5 significantly promoted the removal of crude oil in soil, reaching 64.92% after 30 d, which was 2.1 times the removal rate of C5. The addition of SA/GO/C5 promoted the abundance of soil exogenous Bacillus C5 and indigenous crude oil degrading bacteria Alcanivorax and Marinobacter. In addition, the enrichment of hydrocarbon degradation-related functional abundance was predicted by PICRUSt2 in the SA/GO/C5 treatment group. This study demonstrated that SA/GO/C5 is an effective method for remediating crude oil-contaminated soil, providing a basis and option for immobilized microorganisms bioaugmentation to remediate organic contaminated soil.

Environment impact assessment of agricultural diesel engines utilizing biodiesel derived from phoenix sylvestris oil.

Uncontrolled emissions, massive price increases, and other factors encourage searching for a suitable diesel engine fuel alternative. In its processed form, vegetable oil biodiesel is an appealing green alternative fuel for compression ignition engines. Vegetable oil esters have qualities comparable to those of standard diesel fuel. As a result, biodiesel may be utilized to run a diesel engine without any further alterations. This article analyses the potential of Phoenix sylvestris oil, which may be found in forest belts across the globe, as a viable feedstock for biodiesel extraction. Phoenix sylvestris oil is found to be abundant in different forest belts worldwide. The free fatty acid must first be transformed into esters using catalytic acid esterification before proceeding to alkaline catalytic esterification. The molar ratio (6:1), catalyst concentration (1 wt%), reaction temperature (60 °C), and reaction time (2 h) have all been optimized for biodiesel extraction. Biodiesel produced had characteristics that were similar to standard biodiesel specifications. The biodiesel yield from Phoenix sylvestris oil was 92.3% under optimum conditions. The experimental results revealed that the Phoenix sylvestris oil biodiesel performed better than neat Phoenix sylvestris oil and its blends. Phoenix sylvestris oil blend produced better brake thermal efficiency with lower smoke, hydrocarbon, and CO emissions. The biodiesel produced from non-edible Phoenix sylvestris oil has the potential to be employed as a viable alternative to diesel fuel.

CO2 improves the anaerobic biodegradation intensity and selectivity of heterocyclic hydrocarbons in heavy oil.

Heterocyclic hydrocarbons pollution generated by oil spills and oilfield wastewater discharges threatens the ecological environment and human health. Here we described a strategy that combines the greenhouse gas CO2 reduction with microbial remediation. In the presence of nitrate, CO2 can improve the biodegradation efficiency of the resins and asphaltenes in heavy oil, particularly the biodegradation selectivity of the polar heterocyclic compounds by the newly isolated Klebsiella michiganensis. This strain encoded 80 genes for the xenobiotic biodegradation and metabolism, and can efficiently utilize CO2 when degrading heavy oil. The total abundance of resins and asphaltenes decreased significantly with CO2, from 40.816% to 26.909%, to 28.873% with O2, and to 36.985% with N2. The transcripts per million (TPM) value of accA gene was 57.81 under CO2 condition, while respectively 8.86 and 21.23 under O2 and N2 conditions. Under CO2 condition, the total relative percentage of N1-type heterocyclic compounds was selectively decreased from 32.25% to 22.78%, resulting in the heavy oil viscosity decreased by 46.29%. These results demonstrated a novel anaerobic degradation mechanism that CO2 can promote the anaerobic biodegradation of heterocyclic hydrocarbons in heavy oil, which provides a promising biotreatment technology for the oil-contaminated water.

Catalytic co-pyrolysis of oil palm trunk and polypropylene with Ni-Mo/TiO2 and Ni/Al2O3: Oil composition and mechanism.

Pyrolysis oil from oil palm biomass can be a sustainable alternative to fossil fuels and the precursor for synthesizing petrochemical products due to its carbon-neutral properties and low sulfur and nitrogen content. This work investigated the effect of applying mesoporous acidic catalysts, Ni-Mo/TiO2 and Ni/Al2O3, in a catalytic co-pyrolysis of oil palm trunk (OPT) and polypropylene (PP) from 500 to 700 °C. The obtained oil yields varied between 12.67 and 19.50 wt.% and 12.33-17.17 wt.% for Ni-Mo/TiO2 and Ni/Al2O3, respectively. The hydrocarbon content in oil significantly increased up to 54.07-58.18% and 37.28-68.77% after adding Ni-Mo/TiO2 and Ni/Al2O3, respectively. The phenolic compounds content was substantially reduced to 8.46-20.16% for Ni-Mo/TiO2 and 2.93-14.56% for Ni/Al2O3. Minor reduction in oxygenated compounds was noticed from catalytic co-pyrolysis, though the parametric effects of temperature and catalyst type remain unclear. The enhanced deoxygenation and cracking of phenolic and oxygenated compounds and the PP decomposition resulted in increased hydrocarbon production in oil during catalytic co-pyrolysis. Catalyst addition also promoted the isomerization and oligomerization reactions, enhancing the formation of cyclic relative to aliphatic hydrocarbon.

Global decrease in blood lead concentrations due to the removal of leaded gasoline.

Lead (Pb) is a chemical element with extreme toxicity that is classified as one of the ten chemicals of most significant concern to human health. The main problem involving Pb is its use as a fuel additive (tetraethyllead - TEL) at a global level, which raised the atmospheric Pb concentrations. It is estimated that between 80 and 90% of the atmospheric Pb in large cities came from the use of TEL, and as a consequence, it was also the main source responsible for human exposure to the element. Therefore, this work aimed to evaluate, through a systematic review, the blood concentrations of Pb in scientific articles published in the first two decades of the 2000s to compare the global and regional trends of each continent over time. Our data show the importance of removing TEL in decreasing human exposure to Pb worldwide. We observed exponentially decreasing blood Pb concentrations over the years after additive removal on all continents, resulting in a global trend which TEL's use was the major process governing human exposure worldwide. In addition, the results also showed that, despite the removal of Pb additives lowering levels of human blood Pb, the general population remains exposed to the element through exogenous and endogenous sources. The exhaust Pb particles were deposited into the environment in proportion to the traffic flows, and the legacy of Pb in the environment requires novel primary prevention remedy to curtail exposure.

Biodegradation of petroleum hydrocarbons based pollutants in contaminated soil by exogenous effective microorganisms and indigenous microbiome.

Microbial remediation is an eco-friendly and promising approach for the restoration of sites contaminated by petroleum hydrocarbons (PHCs). The degradation of total petroleum hydrocarbons (TPHs), semi volatile organic compounds (SVOCs) and volatile organic compounds (VOCs) of the soil samples collected from a petrochemical site by indigenous microbiome and exogenous microbes (Saccharomyces cerevisiae ATCC 204508/S288c, Candida utilis AS2.281, Rhodotorula benthica CBS9124, Lactobacillus plantarum S1L6, Bacillus thuringiensis GDMCC1.817) was evaluated. Community structure and function of soil microbiome and the mechanism involved in degradation were also revealed. After bioremediation for two weeks, the concentration of TPHs in soil samples was reduced from 17,800 to 13,100 mg/kg. The biodegradation efficiencies of naphthalene, benzo[a]anthracene, benzo[b]fluoranthene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene, dibenzo[a,h]anthracene, 1,2,3-trichloropropane, 1,2-dichloropropane, ethylbenzene and benzene in soil samples with the addition of S. cerevisiae were 38.0%, 35.7%, 36.2%, 40.4%, 33.6%, 36.2%, 12.0%, 43.9%, 43.3% and 43.0%, respectively. The microbial diversity and community structure were improved during the biodegradation process. S. cerevisiae supplemented soil samples exhibited the highest relative abundance of the genus Acinetobacter for bacteria and Saccharomyces for yeast. The findings offer insight into the correlation between microbes and the degradation of PHC-based pollutants during the bioremediation process.

Intrasexual cuticular hydrocarbon dimorphism in a wasp sheds light on hydrocarbon biosynthesis genes in Hymenoptera.

Cuticular hydrocarbons (CHCs) cover the cuticle of insects and serve as desiccation barrier and as semiochemicals. While the main enzymatic steps of CHC biosynthesis are well understood, few of the underlying genes have been identified. Here we show how exploitation of intrasexual CHC dimorphism in a mason wasp, Odynerus spinipes, in combination with whole-genome sequencing and comparative transcriptomics facilitated identification of such genes. RNAi-mediated knockdown of twelve candidate gene orthologs in the honey bee, Apis mellifera, confirmed nine genes impacting CHC profile composition. Most of them have predicted functions consistent with current knowledge of CHC metabolism. However, we found first-time evidence for a fatty acid amide hydrolase also influencing CHC profile composition. In situ hybridization experiments furthermore suggest trophocytes participating in CHC biosynthesis. Our results set the base for experimental CHC profile manipulation in Hymenoptera and imply that the evolutionary origin of CHC biosynthesis predates the arthropods' colonization of land.

Treatment of petroleum hydrocarbon contaminated soil by combination of electro-Fenton and biosurfactant-assisted bioslurry process.

Removing petroleum hydrocarbons (PHCs) from polluted soil is challenging due to their low bioavailability and degradability. In this study, an experiment was carried out to treat soil polluted with petroleum hydrocarbon using a hybrid electro-Fenton (with BDD anode electrode) and biological processes stimulated with long-chain rhamnolipids (biosurfactants). Electro-Fenton treatment was applied as a pretreatment before the biological process to enhance PHC biodegradability, which would benefit the subsequent biological process. The effects of initial pH, hydroxide concentration, soil organic matter composition, PHCs intermediates during the electro-Fenton process, and total numbers of bacteria in the biological process were analyzed to determine the optimum conditions. The results showed that the optimized electrolysis time for the electro-Fenton was 12 h. The change induced during pretreatment at a specified time was found suitable for the biological process stage and led to 93.6% PHC degradation in combination with the electro-Fenton-and-biological process after 72 h. The combined system's performance was almost 40% higher than individual electro-Fenton and biological treatments. GC-MS analysis confirms the formation of 9-octadecen-1-ol (Z), 2-heptadecene, 1-nonadecene, 1-heneicosene, and pentacosane as fragmentation during the PHCs degradation process. Thus, the electro-Fenton process as pretreatment combined with a biological process stimulated with rhamnolipids (biosurfactants) could be effectively applied to remediate soil polluted with PHCs. However, the system needs further research and investigation to optimize electrolysis time and biosurfactant dose to advance this approach in the soil remediation process.

Evaluation of scale-up effect on cold-active enzyme production and biodegradation tests using pilot-scale bioreactors and a 3D soil tank.

Despite recent attention being paid to the biodegradation of petroleum hydrocarbons in cold environments, scale-up studies of biodegradation are lacking. Herein, the effect of scale-up on the enzymatic biodegradation of highly contaminated soil at low temperatures was studied. A novel cold-adapted bacteria (Arthrobacter sp. S2TR-06) was isolated that could produce cold-active degradative enzymes (xylene monooxygenase (XMO) and catechol 2,3-dioxygenase (C2,3D)). Enzyme production was investigated on 4 different scales (lab to pilot scale). The results showed a shorter fermentation time, and the highest production of enzymes and biomass (107 g/L for biomass, 109 U/mL, and 203 U/mL for XMO and C2,3D after 24 h) was achieved in the 150-L bioreactor due to enhanced oxygenation. Multi-pulse injection of p-xylene into the production medium was needed every 6 h. The stability of membrane-bound enzymes can be increased up to 3-fold by adding FeSO4 at 0.1% (w/v) before extraction. Soil tests also showed that biodegradation is scale-dependent. The maximum biodegradation rate decreased from 100% at lab-scale to 36% in the 300-L sand tank tests due to limited access of enzymes to trapped p-xylene in soil pores, low dissolved oxygen in the water-saturated zone, soil heterogeneity, and the presence of the free phase of p-xylene. The result demonstrated that formulation of enzyme mixture with FeSO4 and direct injection of enzyme mixture (third scenario) can increase the efficiency of bioremediation in heterogeneous soil. In this study, it was demonstrated that cold-active degradative enzyme production can be scaled up to an industrial scale and enzymatic treatment can be used to effectively bioremediate p-xylene contaminated sites. This study could provide key scale-up guidance for the enzymatic bioremediation of mono-aromatic pollutants in water-saturated soil under cold conditions.

Enhancement of oil forensic methodology through the addition of polycyclic aromatic nitrogen heterocycle biomarkers for diagnostic ratios.

Current oil spill forensic identification of source oils relies upon hydrocarbon biomarkers resistant to weathering. This international technique was developed by the European Committee for Standardization (CEN), under EN 15522-2 Oil Spill Identification guidelines. The number of biomarkers have expanded at pace with technological advances, while distinguishing new biomarkers becomes more challenging due to interference of isobaric compounds, matrix effects, and high cost of weathering experiments. Application of high-resolution mass spectrometry enabled exploration of potential polycyclic aromatic nitrogen heterocycle (PANH) oil biomarkers. The instrumentation showed reduction in isobaric and matrix interferences, allowing for identification of low-level PANH and alkylated PANHs (APANHs). Weathered oil samples, obtained from a marine microcosm weathering experiment, enabled comparison with source oils to identify new, stable forensic biomarkers. This study highlighted eight new APANH diagnostic ratios that expanded the biomarker suite, increasing the confidence for identifying highly weathered oils back to their source oil.

New Evidence on the Reliable Use of Stable Isotopes of Bitumen Fractions in Archaeological Research.

One of the goals of archaeological studies is to determine how material goods and ideas moved among human populations, and bitumen is a worthy proxy because it has been used since prehistory. As a result, when bitumen is excavated from archaeological sites, determining its provenance is important because it sheds light on the trade and communication of populations at a given time. During the study of archaeological bitumen from coastal sites in central and southern Puglia (Italy), we observed that stable isotope ratios of saturated and aromatic fractions were incompatible with those obtained from asphaltenes, supporting the absorption of a foreign substance. Experiments showed that lipids are absorbed by bitumen and, in the case of oils, are distributed mainly in the saturated and aromatic fractions as their isotopic ratios change. The same experiments showed that the isotopic ratios of the asphaltenes do not change. Lipid absorption on the archaeological bitumen may have occurred before the bitumen was applied to the pottery, during the use of the pottery or while underground, before being excavated. These hypotheses are discussed, and it is concluded that the isotopic ratio of asphaltenes is a reliable proxy for provenance, whereas those of the saturated and aromatic fractions should be considered with caution due to possible lipid absorption. Nevertheless, they provide new information on pottery use that can be used in archaeological chemistry.

Baseline distribution of petroleum hydrocarbon contamination in the marine environment around the coastline of Qatar.

Levels of organic contaminants (TPHs, PAHs) were simultaneously determined in both abiotic (sediments, seawater) and biotic (Pinctada radiata oysters) samples at four sites along the coastline of Qatar (Arabian Gulf) in 2017-2018. TPHs and PAHs were more frequently detected in oyster tissues than sediment and seawater samples collected from the same areas. While levels of TPHs and PAHs in seawater and sediments were lower than previous local studies and worldwide studies, PAHs levels observed in pearl oyster tissue (25.9-2240 µg/kg) were relatively higher than in previous studies in Qatar. In general, eight PAHs compounds were detected in oyster tissue, with benzo(a)pyrene displaying the highest concentration. The coast of Qatar could be affected by seasonal patterns of pollutants, where TPHs and PAHs levels increased in winter compared to summer. These results provide key information on the use of the pearl oyster as a bioindicator species and Qatar's marine environment.

A review of the occurrence, distribution, and impact of bitumen seeps on soil and groundwater in parts of southwestern Nigeria.

The impact of bitumen components on soil and groundwater resources is of environmental importance. Contaminants' influx into the environment from bitumen components through anthropogenic activities such as exploration, mining, transportation, and usage of bitumen in all its forms have been reported globally. However, gaps exist in the geogenic occurrence of bitumen in the shallow subsurface such as in southwest Nigeria, contaminating the soil and groundwater resources. This review presents in situ bitumen seeps as a source of geogenic soil and groundwater contaminants in southwestern Nigeria. We conducted a systematic review of literatures based on defined selection criteria. We derived information on the state of knowledge about bitumen seep occurrences and distribution in southwestern Nigeria. Also, the processes that exacerbate bitumen contaminants' influx into soil and groundwater were enunciated. At the same time, case examples highlighted areas for possible in situ bitumen contamination studies in Nigeria. The results of this review showed that a multidisciplinary approach has been employed to assess and monitor the contaminants resulting from the various activities involving the exploitation and application of bitumen in Nigeria. These studies emphasize bitumen contaminants as emanating from anthropogenic sources. The results also suggested that bitumen studies have been mainly exploratory to improve the understanding of the economic potential of the hydrocarbon reserve. Also, recent advances in bitumen contaminants studies accounted for the heterogeneous nature of the bitumen. This allows for the optimized categorization of the mechanism and processes undergone by the different bitumen components when released as environmental contaminants. However, a knowledge gap exists in characterizing and understanding the effects of in situ bitumen seeps as a geogenic source of soil and groundwater contamination. This review identifies the possibility of geogenic soil and groundwater contamination by in situ bitumen seeps in the coastal plain sand of the Dahomey basin in southwestern Nigeria. The impact of the bitumen contaminants on the environment was discussed, while methods for accessing the occurrence and distribution of the bitumen contaminants were highlighted.