Polyaromatic Hydrocarbon Compounds Research Articles

A hybrid system based on the combination of adsorption, electrocoagulation, and wetland treatment for the effective remediation of industrial wastewater from underground coal gasification (UCG)

The study verified the effectiveness of treating post-process underground coal gasification (UCG) wastewater, containing high loads of inorganic and organic pollutants, using constructed wetlands (CW) enhanced by hybrid adsorption and electrocoagulation (EC) techniques. Four different system configurations were tested: wetland, EC/wetland, adsorbent/wetland, and EC/adsorbent/wetland. Each experiment lasted 60 days. The feed and effluents from each treatment step were analysed for their basic physicochemical parameters such as metals and trace elements, phenols, sulphides, cyanides, total organic carbon (TOC), chemical oxygen demand (COD), biological oxygen demand (BOD), benzene, toluene, ethylene, xylene (BTEX), and polyaromatic hydrocarbons (PAHs).Systems with electrocoagulation proved to be effective in the case of metal removal. The best results were obtained for Fe, Ni, Sb and As (up to 96%, 98%, 94% and 82% respectively). The systems were ineffective in removing Mn. All tested systems showed the greatest effectiveness in the treatment of wastewater from phenols, BTEX and CN (almost 100% removal). CWs without preliminary electrocoagulation showed practically 100% effectiveness in removing BTEX after 14 days of treatment. Electrocoagulation was particularly effective in reduction of large quantity of PAH compounds (from 1228 μg/l to below 0.050 μg/l). Effective toxicity reduction from V class to II class after 60 days in comparison with meeting the requirements contained in the Best Available Techniques (BAT) document, showed that all tested systems were favorable in terms of UCG wastewater treatment. A significant decrease in toxicity was observed in just 14 days (around 90% reduction of toxicity measured in TU values for systems without adsorbent and around 75% for systems with adsorbent). The wastewater were still toxic due to the formation of degradation intermediates of organic compounds (BTEX, PAHs, phenol compounds), despite a significant decrease in the concentration of contaminants, therefore toxicity assessment should be one of the evaluation criteria for industrial wastewater treatment.

Direct evidence of gas flushing oil in deep reservoirs: Insight from integrated fluid inclusion analyses

Gas flushing of oil has been proposed as an essential process for forming some condensate gas reservoirs based on laboratory experiments and modeling but such a process has rarely been documented in subsurface reservoirs. Here, we report a unique type of yellow-ringed oil inclusions (YROIs) discovered from a deep reservoir in the Kuqa Foreland Basin, Western China that recorded the gas flushing of oil process in the subsurface. The occurrence, composition, phase state and PVT conditions of YROIs during trapping were investigated using a suite of fluid inclusion analytical methods including fluid inclusion petrography, microthermometry, fluorescence spectroscopy, PVT modeling and molecular composition analysis.YROIs found in the reservoir are three-phase (solid–liquid-vapor) fluid inclusions at room temperature with solid rings of 2–3 μm thickness and estimated volume percentages varying between 5 % and 15 %. When heated the solid ring starts to melt at around 46 °C and homogenized with the liquid phase at or above their corresponding homogenization temperatures of coeval aqueous inclusions. YROIs have fluorescence spectral peaks between 530 nm and 550 nm and an elevated spectral shoulder around 650 nm when measured at room temperature; but most spectra show a distinct “blue shift” and an absence of the 650 nm shoulder when measured at their homogenization temperatures. Some YROIs with thick yellow rings show dual spectral peaks at 570 nm and 630 nm at room temperature and their spectral peaks do not change when remeasured at their homogenization temperatures. Molecular compositions derived from synchronous fluorescence spectra and GC-MS analysis suggest that the compositions of YROIs are rich in polyaromatic compounds. PVT modeling indicates that YROIs were trapped under high pressure conditions with a pressure exceeding 50 % of the corresponding hydrostatic pressure.YROIs are interpreted to have been trapped under an elevated temperature and overpressure condition (around 110 °C and 60 MPa) relating to an intensive (wet) gas flushing of an early-charged wax-rich oil. When light hydrocarbon components in the reservoir oil were partially removed by gas, the wax/resin components rich in polyaromatic hydrocarbon compounds may precipitate due to physio-chemical fractionation. YROIs were entrapped in subsurface from a heterogeneous hydrocarbon fluid containing variable amounts of wax/resin colloids, which subsequently coalesce to form solid rings adhering to the inner wall of oil inclusions at room temperature. The presence of yellow-ringed oil inclusions in a reservoir may be indicative of a rapid gas flushing of waxy oil under high pressure, and their minimum homogenization temperature may approximate their trapping temperature.

Controlling the Photophysical Properties of a Series of Isostructural d6 Complexes Based on Cr0, MnI, and FeII.

Development of first-row transition metal complexes with similar luminescence and photoredox properties as widely used RuII polypyridines is attractive because metals from the first transition series are comparatively abundant and inexpensive. The weaker ligand field experienced by the valence d-electrons of first-row transition metals challenges the installation of the same types of metal-to-ligand charge transfer (MLCT) excited states as in precious metal complexes, due to rapid population of energetically lower-lying metal-centered (MC) states. In a family of isostructural tris(diisocyanide) complexes of the 3d6 metals Cr0, MnI, and FeII, the increasing effective nuclear charge and ligand field strength allow us to control the energetic order between the 3MLCT and 3MC states, whereas pyrene decoration of the isocyanide ligand framework provides control over intraligand (ILPyr) states. The chromium(0) complex shows red 3MLCT phosphorescence because all other excited states are higher in energy. In the manganese(I) complex, a microsecond-lived dark 3ILPyr state, reminiscent of the types of electronic states encountered in many polyaromatic hydrocarbon compounds, is the lowest and becomes photoactive. In the iron(II) complex, the lowest MLCT state has shifted to so much higher energy that 1ILPyr fluorescence occurs, in parallel to other excited-state deactivation pathways. Our combined synthetic-spectroscopic-theoretical study provides unprecedented insights into how effective nuclear charge, ligand field strength, and ligand π-conjugation affect the energetic order between MLCT and ligand-based excited states, and under what circumstances these individual states become luminescent and exploitable in photochemistry. Such insights are the key to further developments of luminescent and photoredox-active first-row transition metal complexes.

Treatment Technologies for Removal of Polyaromatic Hydrocarbon Compounds from Wastewater: A Review

Industry discharges, home effluents, and/or urban runoff can all introduce polyaromatic hydrocarbon compounds (PAHs) into a treatment center. Regrettably, due to their chemical stability and resistance to biological degradation, PAHs are regarded as organic pollutants that persist. As a consequence, PAHs have indeed been identified as a possible source of skin, lung, and bladder cancer in humans. Due to PAHs' potential to cause cancer and/or mutation, their residues in treated wastewater are now subject to stricter legal regulation. adsorption ,membrane filtration, coagulation, electrocoagulation, flocculation, advanced oxidation reactions, phytoremediation and bioremediation process are some of the techniques used to remove PAHs from wastewater. In order to reduce environmental contamination, it is important to study different treatment technologies to treat wastewater. The aim of this paper is to highlighting and discussing some of treatment technologies for removing PAHs.

Visualization of π-hole in molecules by means of Kelvin probe force microscopy

Submolecular charge distribution significantly affects the physical-chemical properties of molecules and their mutual interaction. One example is the presence of a π-electron-deficient cavity in halogen-substituted polyaromatic hydrocarbon compounds, the so-called π-holes, the existence of which was predicted theoretically, but the direct experimental observation is still missing. Here we present the resolution of the π-hole on a single molecule using the Kelvin probe force microscopy, which supports the theoretical prediction of its existence. In addition, experimental measurements supported by theoretical calculations show the importance of π-holes in the process of adsorption of molecules on solid-state surfaces. This study expands our understanding of the π-hole systems and, at the same time, opens up possibilities for studying the influence of submolecular charge distribution on the chemical properties of molecules and their mutual interaction.

Reduced commuter exposure to PM2.5 and PAHs in response to improved emission standards in bus rapid transit systems in Mexico

We evaluated impacts of progressive technological updates to bus rapid transit (BRT) systems on in-cabin concentrations of particulate matter with an aerodynamic diameter ≤2.5 μm (PM2.5), and the various polyaromatic hydrocarbons (PAHs) to which commuters were exposed. PM2.5 samples were collected and real-time concentrations measured from October 2017 to March 2020 inside cabins of BRT buses equipped with Euro IV, V and VI diesel emission standards in the Mexico City Metropolitan Area (MCMA). For effective comparison, similar samplings and measurements were carried out on trains in the MCMA underground (MCU) system. Peak in-cabin PM2.5 concentrations decreased significantly (p < 0.05) by 35% from Euro IV to Euro V buses, and by 80% from Euro IV to Euro VI buses. PM2.5 concentrations inside Euro VI buses were significantly lower (p < 0.05) than in Euro IV and Euro V buses and in underground trains. The in-cabin excess (ICE) of PM2.5 relative to ambient concentrations was significantly (p < 0.05) higher for Euro IV than for Euro V buses during morning the traffic peak, and consistently higher than for Euro VI buses. Indeed, ICEs calculated for Euro VI buses were always lower than those for electricity-powered underground trains. The frequency of hotspots decreased from Euro IV to Euro VI buses due to the combined effect of low emissions and closed, air-conditioned cabins. Concentrations of total PAHs including carcinogenic species also decreased from Euro IV to Euro V buses and were below limits of detection aboard Euro VI buses. This work shows that in real-life conditions, advanced diesel technologies and cabin design significantly reduce commuters’ exposure to PM2.5 and to toxic PAH compounds.

Polyaromatic hydrocarbons (PAHs) in the water environment: A review on toxicity, microbial biodegradation, systematic biological advancements, and environmental fate

Polycyclic aromatic hydrocarbons (PAHs) are considered a major class of organic contaminants or pollutants, which are poisonous, mutagenic, genotoxic, and/or carcinogenic. Due to their ubiquitous occurrence and recalcitrance, PAHs-related pollution possesses significant public health and environmental concerns. Increasing the understanding of PAHs' negative impacts on ecosystems and human health has encouraged more researchers to focus on eliminating these pollutants from the environment. Nutrients available in the aqueous phase, the amount and type of microbes in the culture, and the PAHs' nature and molecular characteristics are the common factors influencing the microbial breakdown of PAHs. In recent decades, microbial community analyses, biochemical pathways, enzyme systems, gene organization, and genetic regulation related to PAH degradation have been intensively researched. Although xenobiotic-degrading microbes have a lot of potential for restoring the damaged ecosystems in a cost-effective and efficient manner, their role and strength to eliminate the refractory PAH compounds using innovative technologies are still to be explored. Recent analytical biochemistry and genetically engineered technologies have aided in improving the effectiveness of PAHs' breakdown by microorganisms, creating and developing advanced bioremediation techniques. Optimizing the key characteristics like the adsorption, bioavailability, and mass transfer of PAH boosts the microorganisms' bioremediation performance, especially in the natural aquatic water bodies. This review's primary goal is to provide an understanding of recent information about how PAHs are degraded and/or transformed in the aquatic environment by halophilic archaea, bacteria, algae, and fungi. Furthermore, the removal mechanisms of PAH in the marine/aquatic environment are discussed in terms of the recent systemic advancements in microbial degradation methodologies. The review outputs would assist in facilitating the development of new insights into PAH bioremediation.

Carcinogenic Tattoos?

Millions of people have tattoos. The systemic effects of tattoo colorants (TCs) are mostly unknown. Several tattoos are on the market, which contain carcinogenic compounds such as poly aromatic hydrocarbons compounds or carcinogenic aromatic amines. Using the concept of the EPA for the risk assessment for compounds present in the environment, we estimated an additional lifetime cancer risk of 4.5 per 10000 people with a tattoo of pigment yellow 14. Such a lifetime cancer risk is comparable to the cancer risk estimated for meat consumption.

Performance evaluation and mechanism analysis of halotolerant bacterial strains and cerium oxide nanoparticle to degrade Benzo[a]pyrene

The key source for Benzo[a]pyrene (B[a]P) and various other Polyaromatic hydrocarbon (PAH) is partial ignition of crude oil, and several other by-products of petroleum and its components. Moreover, industries that utilises coal and further when coal is burnt during various natural and anthropogenic activities also leads B[a]P to cause great threat to the environment by getting mixed in the air. The PAH compounds are highly enduring, bio-toxic, cytotoxic, and cancerous. The aqua-phobic property of these hydrocarbons makes these stable and unreactive. Among various other environments marine environment is under great threat due to various anthropogenic activities like an oil leak accidents and industrial emission, specifically from factories. Due to the rapidly varying industrial trends the harmful pollutants get released into the saline and hypersaline environment. Thus, it is the need of the hour to find a way to degrade these toxic chemicals in the environment. Many physicochemical techniques to remediate B[a]P include chemical oxidation, photo-dissociation, burning, landfilling, volatilisation, and adsorption. The by-products from all the techniques cause severe harm to the environment. Here we describe the Benzo[a]pyrene degradation by employing two techniques, first through biodegradation and second using cerium oxide nanoparticles synthesised employing sol gel method. This current work aims to compare the degradation of B[a]P using both bacterial cocultures (Biological) and CeO2 nanoparticle (Chemical method). Mechanism of Biodegradation of B[a]P is proposed to take place by the hydroxylation through oxidation of aromatic ring, tracked by cis-dihydrodiol intermediates formation, finally resulting in cleavage to simple alcohols, carbonyl compounds, phenolics and carboxylic acids. The interpretation of the Mass spectrum also revealed some non-reported low molecular weight compounds like cyclopentadienyl, cyclobutadienyl cations, diacetylene and DHP, along with O-Cresol, Benzaldehyde, Benzoic acid, Naphthalene, Naphthol, Diacetylene and Dihydropyran. On comparing with biodegradation, the degradation using cerium oxide nanoparticles gave many simple, and fewer toxic by-products. • Halotolerant B[a]P degrading bacterial strains were isolated from marine environment. • Strains were screened and optimised for enhanced degradation of B[a]P. • Synthesis (citrate–nitrate sol–gel route) & characterisation of CeO 2 nanoparticles. • Degradation of benzo[a]pyrene of CeO 2 NP in the visible light. • Comparative study on bio and CeO 2 nanoparticle B[a]P degradation.

Biochar from waste Sterculia foetida and its application as adsorbent for the treatment of PAH compounds: Batch and optimization

Polyaromatic hydrocarbons (PAHs) are organic pollutants with known health hazards and have been reported worldwide in many water sources. The present study reports the easy and green formulation of KOH-modified biochar from Sterculia foetida shells capable of adsorbing acenaphthene and naphthalene from water. To elevate process efficiency, response surface methodology (RSM) was applied to optimize the sorption process. Batch study data were also analysed to understand the process isothermal, thermodynamic and kinetic characteristics. Characterization of the biochar was done using SEM, EDS, BET, FT-IR and XRD. The results display that the formulated biochar was able to remove approximately 92% and 94% of acenaphthene and naphthalene respectively from aqueous solutions. Further the process was found to follow Langmuir and Temkin isotherms and pseudo-second-order kinetics. The thermodynamic study suggested that the adsorption was endothermic and spontaneous in nature. The activation energy of the process suggested that chemical adsorption was the mode of PAH removal.

Hazard evaluation of air pollution by using the key characteristics approach

The key characteristic (KC) as a new approach based on mechanistic evidence has been shown by the IARC Monographs Program working group. Human carcinogens like exhibit one or more key characteristics that are related to how they cause cancer, and different carcinogenic agents exhibit different spectra of these key characteristics. Air pollution is one of the major concerns of human health for the people who lives in Asia because air pollution contains many different human carcinogens including heavy metals, volatile compounds. electrophile compounds and polyaromatic hydrocarbon compounds. In this study, we investigated air pollution mixtures derived from diesel and gasoline engine exhausts by a mechanism-based approach. We first conducted a KC analysis of organic compounds of diesel exhaust in IARC monograph 105 using data of biological test results from the PubChem database. As a result, it was found that some PAH among those compounds is highly responsive to aryl hydrocarbon receptor, nuclear factor erythroid 2 like 2, NR1I2/3 nuclear receptor subfamily 1 group I member 2/3. Further, we analyzed KCs of water-extract mixtures from diesel exhaust particle (DEP-WM) using gene expression values in the mouse lung responded induced by exposures to DEP-WM. The KC of DEP-WM showed lipid related-nuclear receptor signaling and apoptotic pathway, suggesting that DEP-WM affects lipid metabolism in lung tissues. Thus, the KC method will be useful for high-precision assessment of a mixture of air pollution.

Isolation, Selection and Identification of Polyaromatic Hydrocarbons (PAHs) Degrading Bacteria from Heavy Oil Waste (HOW)-Contaminated Soil

The heavy oil waste (HOW) containing polyaromatic hydrocarbon (PAHs) is a persistent organic pollutants (POPs) that difficult to degrade. The new PAH degrading consortium was investigated from HOW contaminated soil in North Sumatera of Indonesia. The isolation, selection and identification of polyaromatic hydrocarbon degrading bacteria from soil contaminated by HOW was conducted to solve a bioremediation process. The isolation microbes from soil contaminated by HOW was performed using a minimum ONR7a media and followed on marine agar media for purification purposes. From the performed isolation results, 11 isolates were able to degrade PAHs compounds, such as phenanthrene, dibenzothiophene, or fluorene compounds. They grew at pH range of 4.8-8.2 and performed on emulsification activity in paraffin from 0.150-0.662. Three of them showed the best performance on HOW biodegradation capability and then successfully selected and identified as Salipiger sp., Bacillus altitudinis, and Ochrobactrum anthropi. using 16S rDNA. The HOW biodegradation as TPH-degradation were 38.66%, 59.60%, and 47.16%, respectively. Those isolated bacteria could potentially be as bioremediation agents to develop on bioremediation process for soils contaminated by HOW.

Thermochemical conversion of waste engine oil (WEO) to gasoline-rich crude oil

Thermolysis of Waste Engine oil (WEO) was performed in a semi-batch reactor in the temperature range of 450–575 °C. The highest yield of pyrolytic oil was obtained (76.73%) at 550 °C temperature. The comparative study between the thermogravimetric analysis (TGA) and pyrolysis experiment disclosed that the conversion of WEO was 99.34% in TGA and 98.23% in pyrolysis experiment. The fuel properties such as density (795 g cc−1), calorific value (42.40 MJ kg−1), and flash point (33 °C) of the pyrolytic oil were less compared to petrol. The decrease in the concentration of Ca, Fe, Mg, Ni, Pb, As, Mn, Zn, and Cu in the pyrolytic oil compared to WEO was perceived. The transformation in the chemical compositions in the pyrolytic oil during the course of pyrolysis was noticed. The pyrolytic oil had a composition of 38% aromatics, 32.97% alkanes, 7.97% cyclo-alkanes, 11.9% alkenes, and 4.78% poly-aromatic hydrocarbons compounds was lower than that of WEO. The WEO pyrolytic oil was containing 65% of gasoline ranged hydrocarbon compounds (C9–C12) along with 24.53% of kerosene (C11–C15), 7.47% of diesel (C15–C19), and 15.32% of heavy fuel oil (˃ C19).

Observed Daily Profiles of Polyaromatic Hydrocarbons and Quinones in the Gas and PM1 Phases: Sources and Secondary Production in a Metropolitan Area of Mexico

The diel variation of meteorological conditions strongly influences the formation processes of secondary air pollutants. However, due to the complexity of sampling highly reactive chemical compounds, significant information about their transformation and source can be lost when sampling over long periods, affecting the representativeness of the samples. In order to determine the contribution of primary and secondary sources to ambient levels of polyaromatic hydrocarbons (PAHs) and quinones, measurements of gas and PM1 phases were conducted at an urban site in the Guadalajara Metropolitan Area (GMA) using a 4-h sampling protocol. The relation between PAHs, quinones, criteria pollutants, and meteorology was also addressed using statistical analyses. Total PAHs (gas phase + PM1 phase) ambient levels ranged between 184.03 ng m−3 from 19:00 to 23:00 h and 607.90 ng m−3 from 07:00 to 11:00 h. These figures both coincide with the highest vehicular activity peak in the morning and at night near the sampling site, highlighting the dominant role of vehicular emissions on PAHs levels. For the gas phase, PAHs ranged from 177.59 to 595.03 ng m−3, while for PM1, they ranged between 4.81 and 17.44 ng m−3. The distribution of the different PAHs compounds between the gas and PM1 phases was consistent with their vapour pressure (p °L) reported in the literature, the PAHs with vapour pressure ≤ 1 × 10−3 Pa were partitioned to the PM1, and PAHs with vapour pressures ≥ 1 × 10−3 Pa were partitioned to the gas phase. PAHs diagnostic ratios confirmed an anthropogenic emission source, suggesting that incomplete gasoline and diesel combustion from motor vehicles represent the major share of primary emissions. Quinones ambient levels ranged between 18.02 ng m−3 at 19:00–23:00 h and 48.78 ng m−3 at 15:00–19:00 h, with significant increases during the daytime. The distribution of quinone species with vapour pressures (p °L) below 1 × 10−4 Pa were primarily partitioned to the PM1, and quinones with vapour pressures above 1 × 10−4 Pa were mainly partitioned to the gas phase. The analysis of the distribution of phases in quinones suggested emissions from primary sources and their consequent degradation in the gas phase, while quinones in PM1 showed mainly secondary formation modulated by UV, temperature, O3, and wind speed. The sampling protocol proposed in this study allowed obtaining detailed information on PAHs and quinone sources and their secondary processing to be compared to existing studies within the GMA.

Genome Organization and Adaptive Potential of Archetypal Organophosphate Degrading Sphingobium fuliginis ATCC 27551.

Sphingobium fuliginis ATCC 27551, previously classified as Flavobacterium sp. ATCC 27551, degrades neurotoxic organophosphate insecticides and nerve agents through the activity of a membrane-associated organophosphate hydrolase. This study was designed to determine the complete genome sequence of S. fuliginis ATCC 27551 to unravel its degradative potential and adaptability to harsh environments. The 5,414,624 bp genome with a GC content of 64.4% is distributed between two chromosomes and four plasmids and encodes 5,557 proteins. Of the four plasmids, designated as pSF1, pSF2, pSF3, and pSF4, only two (pSF1 and pSF2) are self-transmissible and contained the complete genetic repertoire for a T4SS. The other two plasmids (pSF3 and pSF4) are mobilizable and both showed the presence of an oriT and relaxase-encoding sequences. The sequence of plasmid pSF3 coincided with the previously determined sequence of pPDL2 and included an opd gene encoding organophosphate hydrolase as a part of the mobile element. About 15,455 orthologous clusters were identified from among the cumulatively annotated genes of 49 Sphingobium species. Phylogenetic analysis done using the core genome consisting of 802 orthologous clusters revealed a close relationship between S. fuliginis ATCC 27551 and bacteria capable of degradation of polyaromatic hydrocarbon compounds. Genes coding for transposases, efflux pumps conferring resistance to heavy metals, and TonR-type outer membrane receptors are selectively enriched in the genome of S. fuliginis ATCC 27551 and appear to contribute to the adaptive potential of the organism to challenging and harsh environments.

SURFACE AND ADHESION PROPERTIES STUDY OF PROPHYLACTIC LUBRICANTS BORDER LAYERS ON METALLIC SURFACE

This study is aimed the developing the special petroleum products, namely, preventive lubricants (PL) used in the field of solid minerals transportation. The surface and adhesion characteristics of the prophylactic compositions developed earlier on the basis of thermodestructive and thermocatalytic processes products of oil refining are investigated. It is set that the prophylactic agents contain the far of surface active substances, such as resins, pyrobitumens and other polyaromatic hydrocarbon compounds: in the heavy gas-oil of the catalytic cracking their content is above 45.96 %, in an easy gas-oil – 15.07 %, that results in the improvement of viscosity-temperature properties of products and promotes their oiling ability. The basic amount of compounds with high superficial activity is contained in heavy fractions of oil, and in the process of processing concentrated in a petroleum residue - petroleum tar that was used as depression addition in mixtures of prophylactic agents. For protecting of metallic surfaces of mountain transport from a direct contact with the transported material in the conditions of the lowered temperatures it is recommended to apply composition of the catalytic cracking mixtures with content of petroleum tar from 2 to 5%. &lt;span style="opacity: 0;"&gt; . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . &lt;/span&gt;

Effects of plant density on the bioremediation of soils contaminated with polyaromatic hydrocarbons

This study aims to evaluate the effects of plant density on the degradation of polyaromatic hydrocarbon (PAH) compounds in soils contaminated with crude oil. In this work, Axonopus compressus was applied as a bioremediator given its extensive and successful use in phytoremediation. A. compressus was planted at the density of three (pot-3), five (pot-5) or seven (pot-7) plants in pots containing soil contaminated with crude oil at the concentration of 20 g kg−1. Two pots were designated as controls: one containing unplanted soil contaminated with crude oil (pot-C) and one containing uncontaminated soil as control (pot-0). All planted and unplanted pots were irrigated with nutrient solution as needed. This study was performed for 2 months. The degradation of PAH compounds in soil was evaluated through ultraviolet fluorescence technique. Results showed that PAH degradation was enhanced as plant density increased. Specifically, after 2 months, PAH contents decreased by 69%, 75.8% and 82.3% in pot-3, pot-5 and pot-7, respectively, relative to those in pot-C. High plant densities mitigated the adverse effects of crude oil contamination on plant growth. Thus, this study demonstrated that high plant densities promote the phytoremediation of soil contaminated with hydrocarbon compounds.

Determination of Polycyclic aromatic hydrocarbons (PAHs) in Yerba-maté herbal drink

Yerba-maté (Y-M), known as llex-paraquariensis is traditional South American herbal drink that is consumed as an aqueous extract from the Y-M leaves. This drink is thought to have long-term health benefits and thus it has recently gained more popularity. However, health hazards of polyaromatic hydrocarbons (PAHs) deposited in Y-M during drying process has been linked to the development of different types of cancer in particular oesophageal cancer. The current study developed and validated an extraction and analytical method to determine the presence of one of the PAH compounds, namely; benzo(b)fluoranthene [Bbf] as an indicator for the PAH(s) occurrence in Y-M in commercial samples of the dried leaves. Since the expected level of contamination with this compound is at trace level thus a sensitive and selective analytical method was needed. Gas Chromatography-Mass Spectrometry GC-MS method was developed using selected ion monitoring (SIM) with split-less mode focusing on 126 ion and 252 ion (main) for [Bbf]. The content of [Bbf] using different extraction methods was found in a range 0.02 to 0.09 μg/g. GC-MS results indicated a good repeatability of the peak area with strong correlation and linearity between mean peak area and concentration from the calibration curve. Soxhlet extraction using hexane as a solvent gave the highest yield of [Bbf] concentration. However, ultrasonic extraction using hot distilled water as a solvent is recommended as it better simulates the way of making and drinking.

Impact of the 0.1% fuel sulfur content limit in SECA on particle and gaseous emissions from marine vessels

Emissions were measured on-board a ship in the Baltic Sea, which is a sulfur emission control area (SECA), before and after the implementation of the strict fuel sulfur content (FSC) limit of 0.1 m/m% S on the 1st of January 2015. Prior to January 2015, the ship used a heavy fuel oil (HFO) but switched to a low-sulfur residual marine fuel oil (RMB30) after the implementation of the new FSC limit. The emitted particulate matter (PM) was measured in terms of mass, number, size distribution, volatility, elemental composition, content of organics, black and elemental carbon, polycyclic aromatic hydrocarbons (PAHs), microstructure and micro-composition, along with the gaseous emissions at different operating conditions. The fuel change reduced emissions of PM mass up to 67%. The number of particles emitted remained unchanged and were dominated by nanoparticles. Furthermore, the fuel change resulted in an 80% reduction of SO2 emissions and decreased emissions of total volatile organic compounds (VOCs). The emissions of both monoaromatic and lighter polyaromatic hydrocarbon compounds increased with RMB30, while the heavy, PM-bound PAH species that belong to the carcinogenic PAH family were reduced. Emissions of BC remained similar between the two fuels. This study indicates that the use of low-sulfur residual marine fuel oil is a way to comply with the new FSC regulation and will reduce the anthropogenic load of SO2 emissions and secondary PM formed from SO2. Emissions of primary particles, however, remain unchanged and do not decrease as much as would be expected if distilled fuel was used. This applies both to the number of particles emitted and some toxic components, such as heavy metals, PAHs or elemental carbon (EC). The micro-composition analyses showed that the soot particles emitted from RMB30 combustion often do not have any trace of sulfur compared with particles from HFO combustion, which always have a sulfur content over 1%m/m. The soot sulfur content can impact aging and cloud condensation properties. This study is an in-depth comparison of the impact of these two fuels on the emissions of particles as well as their composition and microstructure. To evaluate the impact of the use of low-sulfur residual marine fuel oils on emissions from ships, additional research is needed to investigate the varied fuel types and compositions as well as the wide range of engine conditions and properties.

Degradation of oil products in a soil from a Russian Barents hot-spot during electrodialytic remediation.

A highly oil-polluted soil from Krasnoe in North-West Russia was used to investigate the degradation of organic pollutants during electrodialytic remediation. Removal efficiencies were up to 70 % for total hydrocarbons (THC) and up to 65 % for polyaromatic hydrocarbons (PAH). Relatively more of the lighter PAH compounds and THC fractions were degraded. A principal component analysis (PCA) revealed a difference in the distribution of PAH compounds after the remediation. The observed clustering of experiments in the PCA scores plot was assessed to be related to the stirring rate. Multivariate analysis of the experimental settings and final concentrations in the 12 experiments revealed that the stirring rate of the soil suspension was by far the most important parameter for the remediation for both THC and PAH. Light was the second most important variable for PAH and seems to influence degradation. The experimental variables current density and remediation time did not significantly influence the degradation of the organic pollutants. Despite current density not influencing the remediation, there is potential for degrading organic pollutants during electrodialytic removal of heavy metals, as long as a stirred set-up is applied. Depending on remediation objectives, further optimisation may be needed in order to develop efficient remediation strategies.