Concentrations Of Phenanthrene Research Articles

Phenanthrene metabolism in Panicum miliaceum: anatomical adaptations, degradation pathway, and computational analysis of a dioxygenase enzyme.

Polycyclic aromatic compounds (PAHs) are persistent organic pollutants of environmental concern due to their potential impacts on food chain, with plants being particularly vulnerable. While plants can uptake, transport, and transform PAHs, the precise mechanisms underlying their localization and degradation are not fully understood. Here, a cultivation experiment conducted with Panicum miliaceum exposed different concentrations of phenanthrene (PHE). Intermediate PHE degradation compounds were identified via GC-MS analysis, leading to the proposal of a phytodegradation pathway featuring three significant benzene ring cleavage steps. Our results showed that P. miliaceum exhibited the ability to effectively degrade high levels of PHE, resulting in the production of various intermediate products through several chemical changes. Examination of the localization and anatomical characteristics revealed structural alterations linked to PHE stress, with an observed enhancement in PHE accumulation density in both roots and shoots as treatment levels increased. Following a 2-week aging period, a decrease in the amount of PHE accumulation was observed, along with a change in its localization. Bioinformatics analysis of the P. miliaceum 2-oxoglutarate-dependent dioxygenase (2-ODD) DAO-like protein revealed a 299 amino acid structure with two highly conserved domains, namely 2OG-FeII_Oxy and DIOX_N. Molecular docking analysis aligned with experimental results, strongly affirming the potential link and direct action of 2-ODD DAO-like protein with PHE. Our study highlights P. miliaceum capacity for PAHs degradation and elucidates the mechanisms behind enhanced degradation efficiency. By integrating experimental evidence with bioinformatics analysis, we offer valuable insights into the potential applications of plant-based remediation strategies for PAHs-contaminated environments.

Integrated toxicity of secondary, tertiary, wetland effluents on human stem cells triggered by ERα and PPARγ agonists

Residual pollutants in discharged and reused water pose both direct and indirect human exposure. However, health effects caused by whole effluent remain largely unknown due to the lack of human relevant model for toxicity test. Effluents from four secondary wastewater treatment plants (SWTPs), a tertiary wastewater treatment plant (TWTP) and a constructed wetland (CW) were evaluated for the integrated toxicity of the organic extractions. Multiple-endpoint human mesenchymal stem cells (MSCs) assay was used as an in vitro model relevant to human health. The effluents caused cytotoxicity, oxidative stress and genotoxicity in MSCs. The osteogenic and neurogenic differentiation were inhibited and the adipogenic differentiation were stimulated by some of the effluent extractions. The SWTP, TTP and CW treatments reduced integrated biomarker response (IBR) by 26.3 %, 17.5 % and 33.3 % respectively, where the integrated biomarker response values of final CW (8.3) and TWTP (8.2) effluents were relatively lower than SWTPs (9.1). Among multiple biomarkers, the inhibition of osteogenesis was the least reduced by wastewater treatment. Besides, ozone disinfection in tertiary treatment increased cytotoxicity and differentiation effects suggesting the generation of toxic products. The mRNA expressions of estrogen receptor alpha (ERα) and peroxisome proliferator-activated receptor gamma (PPARγ) were significantly upregulated by effluents. The inhibitory effects of effluents on neural differentiation were mitigated after antagonizing ERα and PPARγ in the cells. It is suggested that ERα and PPARγ agonists in effluents were largely accountable for the impairment of stem cell differentiation. Besides, the concentrations of n-C29H60, o-cresol, fluorene and phenanthrene in the effluents were significantly correlated with the intergrated stem cell toxicity. The present study provided toxicological evidence for the relation between water contamination and human health, with an insight into the key toxicity drivers. The necessity for deep water treatment and the potential means were suggested for improving water quality.

Effect of liming on polycyclic aromatic hydrocarbons leaching from hydrocarbon-contaminated tectogenic industriosol

Soil stabilization/solidification is commonly employed remediation method for contaminated soils. Until now, limited attention has been given to the application of quicklime in polycyclic aromatic hydrocarbons (PAHs) contaminated soil. We treated a tectogenic industriosol spiked with 50 mg kg−1 of four PAHs (12.5 mg kg−1 each of fluorene (FLU), phenanthrene (PHE), fluoranthene (FLT) and pyrene (PYR)) using three different liming agents at 1% (w:w): quicklime (CaO), hydrated lime (Ca(OH)2) and carbonate calcium (CaCO3). All treated samples were leached in water at a solid-liquid ratio of 10, with subsequent analysis of leached soil and leachates for PAHs content. Results revealed that the addition of liming agents led to a reduction in FLU and PHE concentrations in treated soil by 6.81 ± 2.47% and 28.88 ± 4.18%, respectively, compared to a not-treated sol. However, no significant impact was observed on the 4-cycles PAHs (FLT and PYR). The addition of liming agents also significantly decreased the amount of PAHs in the leachate, by 100% for FLU and PHE, and by 74.9 ± 17.5% and 72.3 ± 34.8%, for FLT and PYR, respectively, compared to not limed soil. Among the liming agents, quicklime was the most effective in reducing the amount of 4 cycles PAHs in the leachate. Various mechanisms, such as encapsulation, volatilization and oxidation could contribute to this observed reduction. Quicklime treatment at a concentration of 1% w:w in PAHs-contaminated soil emerges as a promising technique to effectively reduce PAHs concentration in soils and mitigate PAHs mobility through leaching. This study also sheds light on the possibility to limit CO2 emissions and resources exploitation to assure the remediation process, thereby enhancing its overall environmental sustainability.

Numerical study on kinetics of tar production and mechanism of benzene formation during corn straw gasification

Tar production is a key factor hindering the industrialization of biomass gasification technology. Understanding the mechanisms of tar formation can help predict and reduce tar yield. A gasification model was proposed to investigate the effects of oxygen ratio (OR) and temperature on products formation. Its accuracy was validated using experimental data. The relative content of PAHs from corn straw gasification decreased from 95 % to 53 % with OR and temperature increasing, indicating PAHs relative content could be decreased by increasing OR and temperature. The concentrations of phenanthrene from cellulose and corn straw gasification at 900 °C were 0.85 and 378 ppm, separately. The concentrations of pyrene were 52 and 558 ppm, respectively. The content of PAHs from cellulose gasification was much less than that from corn straw gasification. However, the contribution of cellulose to PAHs formation increased with temperature increasing. Furthermore, the mechanism of benzene formation was analyzed qualitatively and quantitatively. C2H2, C3H3, and C4H6 were main precursors and exhibited a considerable role in benzene formation. H, OH, CH3, and C6H5 were the key radicals. The analysis results indicated that CH3→C2H2→C3H3→benzene and C2H3/C2H4→C4H6→n-C4H5→benzene were two main paths for benzene formation during corn straw gasification.

Remediation of phenanthrene by highly efficient CdS–SnS photocatalyst and its cytotoxic assessments

Cadmium sulfide-tin sulfide (CdS–SnS) nanoparticles are a novel kind of photocatalyst. These CdS–SnS nanoparticles are synthesized and characterized using UV–Vis, FT-IR, XRD, SEM-EDX, and DLS techniques, to understand their size distribution, crystalline nature, morphology, shape, optical properties, and elemental composition. This research offers insight into the efficient photocatalytic degradation of Phenanthrene (PHE) using CdS–SnS. The CdS–SnS NPs as photocatalyst can effectively photodegrade the polycyclic aromatic hydrocarbons (PAH) such as phenanthrene under simulated solar and UV light. UV–vis spectra of these nanoparticles exhibit peaks at 365 and 546 cm−1 respectively, the mean size of the CdS–SnS NPs in DLS is determined to be 78 nm. The CdS–SnS stretching frequency was observed at wave numbers below 700 cm−1, the absorption peak at 1123 cm−1 indicates the presence of C–N stretch or CS bond of thiourea, while the peak at 1350.38 cm−1 corresponds to the tris-amine C–N stretch in FT-IR. Additionally, the peaks observed at 2026 cm−1 indicate the presence of isothiocyanate (NCS). 1456.23 cm−1 represents the asymmetric scissor deformation vibration. EDAX revealed the presence of elemental Cd and Sn oxides. The antimicrobial studies showed that the CdS–SnS NPs at the concentration of 150 μg/mL, exhibit maximum inhibition (15 ± 1.25 mm) against the strains Proteus mirabilis followed by Staphylococcus epidermidis and Clostridium spp. Among fungal strains Colletotrichum spp. exhibits the maximum zone of inhibition (9 ± 0.25). This research also observed the cytotoxic effects of CdS–SnS NPs on HepG2 and ZF4 cells. HepG2 cells exhibited 50% inhibition at 50 μg/mL and 70% inhibition at 100 μg/mL concentrations, while ZF4 cells exhibited 50% inhibition at 50 μg/mL and 78% inhibition at 100 μg/mL concentrations, respectively. The parameters like concentration of PHE, concentration of CdS–SnS NPs, pH, and sources of irradiation on batch adsorption were examined to maximize the efficiency of the photodegradation process.

The discrepant metabolic pathways of PAHs by facultative anaerobic bacteria under aerobic and nitrate-reducing conditions

Studies regarding the facultative anaerobic biodegradation of polycyclic aromatic hydrocarbons (PAHs) were still in the initial stage. In this study, a facultative anaerobe which was identified as Bacillus Firmus and named as PheN7 was firstly isolated from the mixed petroleum-polluted soil samples using phenanthrene and nitrate as the solo carbon resource and electron acceptor under anaerobic condition. The degradation rates of PheN7 towards phenanthrene were detected as 33.17 μM/d, 13.81 μM/d and 7.11 μM/d at the initial phenanthrene concentration of 250.17 μM with oxygen, nitrate and sulfate as the electron acceptor, respectively. The metabolic pathways toward phenanthrene by PheN7 were deduced combining the metagenome analysis of PheN7 and intermediate metabolites of phenanthrene under aerobic and nitrate-reducing conditions. Dioxygenation and carboxylation were inferred as the initial activation reactions of phenanthrene degradation in these two pathways. This study highlighted the significance of facultative anaerobic bacteria in natural PAHs biodegradation, revealing the discrepant metabolic fates of PAHs by one solo bacteria under aerobic and anaerobic environments.

Determining buffering capacity of polydimethylsiloxane-based passive dosing for hydrophobic organic compounds in large-volume bioassays

Polydimethylsiloxane (PDMS) is the most widely used material for passive dosing. However, the ability of PDMS to maintain constant water concentrations of chemicals in large-volume bioassays was insufficiently investigated. In this study, we proposed a kinetic-based method to determine the buffering capacity of PDMS for maintaining constant water concentrations of hydrophobic organic contaminants (HOCs) in large-volume bioassays. A good correlation between log Kow and PDMS-water partitioning coefficients (log KPW) was observed for HOCs with log Kow values ranging from 3.30 to 7.42. For low-molecular-weight HOCs, volatile loss was identified as the primary cause of unstable water concentrations in passive dosing systems. Slow desorption from PDMS resulted in a reduction of water concentrations for high-molecular-weight HOCs. The volume ratio of PDMS to water (RV) was the key factor controlling buffering capacity. As such, buffering capacity was defined as the minimum RV required to maintain 90% of the initial water concentration and was determined to be 0.0076–0.032 for six representative HOCs. Finally, passive dosing with an RV of 0.014 was validated to effectively maintain water concentrations of phenanthrene in 2-L and 96-h toxicity tests with adult mosquitofish. By determining buffering capacity of PDMS, this study recommended specific RV values for cost-efficient implementation of passive dosing approaches in aquatic toxicology, particularly in large-volume bioassays.

Screening and Characterization of Polycyclic Aromatic Hydrocarbons Tolerant Fungi from Petrochemical Refinery Effluent

Fungi were isolated from effluent released by petrochemical refinery and screened for their tolerance to 50 mg/L concentration of naphthalene, phenanthrene and pyrene under agitation condition of 150 rpm and ambient temperature over a period of 21 days. Samples were analysed for residual PAH concentrations using HPLC and tolerance ability were calculated in percentages. Fungal growth in mineral salt medium supplemented with PAH was measured in dry weight of mycelial biomass was used as index for assessing their tolerance ability. Out of the 22 fungi isolated, only four were identified as Aspergillus, Talaromyces, Fusarium and Trichoderma species to exhibit tolerance to naphthalene (94.6, 96.9, 99.7 and 99.8%), phenanthrene (91.1, 92.2, 99.5 and 99.8%) and pyrene (89.4, 90.5, 92,6 and 94.2%) respectively. Low molecular weight PAHs (naphthalene and phenanthrene) were better tolerated compared to high molecular weight pyrene. Based on findings made in this study, the four isolates with higher tolerance to PAHs could be recommended for bioremediation of PAH contaminated environments.

Transport proteins and their differential roles in the accumulation of phenanthrene in wheat

The study focuses on the uptake, accumulation, and translocation of polycyclic aromatic hydrocarbons (PAHs) in cereals, specifically exploring the role of peroxidase (UniProt accession: A0A3B5XXD0, abbreviation: PX1) and unidentified protein (UniProt accession: A0A3B6LUC6, abbreviation: UP1) in phenanthrene solubilization within wheat xylem sap. This research aims to clarify the interactions between these proteins and phenanthrene. Employing both in vitro and in vivo analyses, we evaluated the solubilization capabilities of recombinant transport proteins for phenanthrene and examined the relationship between protein expression and phenanthrene concentration. UP1 displayed greater transport efficiency, while PX1 excelled at lower concentrations. Elevated PX1 levels contributed to phenanthrene degradation, marginally diminishing its transport. Spectral analyses and molecular dynamics simulations validated the formation of stable protein-phenanthrene complexes. The study offers crucial insights into PAH-related health risks in crops by elucidating the mechanisms of PAH accumulation facilitated by transport proteins.

Organic minerals in a self-heating coal-waste dump in Upper Silesia, Poland: Structure, formation pathways and environmental issues

The study presents research on the unusual appearance of purple-colored organic minerals, ravatite (phenanthrene) and freitalite (anthracene), occurring in the migrating front wall of a heating spot in the Bytom coal waste dump (Upper Silesia Coal Basin, Poland). These minerals are known to be sublimation products, but their formation mechanism remains unclear. Additional minor components are fluorene, dibenzothiophene, naphthothiophenes, dibenzofuran, and their alkyl-derivatives, and n-C17 – n-C20 alkanes. Temperatures were surprisingly low (30–60 °C on the surface) at the sampling sites, though such large amounts of Polycyclic Aromatic Hydrocarbons (PAHs) typically form in a burning environment where temperatures reach 800–1000 °C. The relatively low temperatures suggest that the primary mechanism of formation was not direct evaporation (desublimation) of phenanthrene and anthracene from coal-waste gases but that their occurrence may reflect a catalytical polymerization of ethylene on iron (III) chloride synthesized in a reaction between HCl and a common Fe mineral such as goethite. Subsequently, both minerals crystallized on the cold dump surface. High concentrations of phenanthrene and anthracene in self-heating products, testified by ravatite and freitalite, mean that self-heating of coal waste may significantly increase backgrounds of environmental pollution by PAHs.

Hierarchical metal-dielectric-metal nanostructures as SERS sensors for sensitive detection of polycyclic aromatic hydrocarbons

Due to the wide variety, inaccessible self-degradation, high mutagenicity and carcinogenicity of polycyclic aromatic hydrocarbons (PAHs), it still remains challenging to efficiently identify them, especially in real environment. Herein, we develop a bottom-up self-assembly strategy to construct a sandwich-like hierarchical metal-dielectric-metal system composed of mercaptan-modified Au nanospheres-graphene oxide (GO)-Ag nanowires as surface-enhanced Raman spectroscopy (SERS) sensors for sensitive detection of PAHs. The synergistic integration of metallic layers and the organic mercaptan and GO layer not only provides localized enhanced electromagnetic field region which is induced by the nanogap between the top Au nanospheres and the bottom Ag nanowires, but also effectively traps PAHs in the middle layer through hydrophobic interaction of mercaptan and π-π stacking interaction of GO. By rationally optimizing the SERS substrates, the lowest detection concentrations of pyrene, anthracene, phenanthrene and benzo[a]pyrene could be reached, respectively, at 10−8 M, 10−8 M, 10−8 M and 10−7 M. The hierarchical system shows excellent uniformity, reproducibility and is able to identify various types of PAHs in multi-component mixtures as well as in real water environment. This strategy can provide a general platform to identify hazardous pollutants that are hydrophobic or contain benzene rings, such as pesticides, dyes and polychlorinated biphenyls.

Mechanism of synergistic remediation of soil phenanthrene contamination in paddy fields by rice-crab coculture and bioaugmentation with Pseudomonas sp.

Polycyclic aromatic hydrocarbons (PAHs) are persistent and harmful pollutants with high priority concern in agricultural fields. This work constructed a rice-crab coculture and bioaugmentation (RCM) system to remediate phenanthrene (a model PAH) contamination in rice fields. The results showed that RCM had a higher remediation performance of phenanthrene in rice paddy compared with rice cultivation alone, microbial addition alone, and crab-rice coculture, reaching a remediation efficiency of 88.92 % in 42 d. The concentration of phenanthrene in the rice plants decreased to 6.58 mg/kg, and its bioconcentration effect was efficiently inhibited in the RCM system. In addition, some low molecular weight organic acids of rice root increased by 12.87 %∼73.87 %, and some amino acids increased by 140 %∼1150 % in RCM. Bioturbation of crabs improves soil aeration structure and microbial migration, and adding Pseudomonas promoted the proliferation of some plant growth-promoting rhizobacteria (PGPRs), which facilitated the degradation of phenanthrene. This coupling rice-crab coculture with bioaugmentation had favorable effects on soil enzyme activity, microbial community structure, and PAH degradation genes in paddy fields, enhancing the removal of and resistance to PAH contamination in paddy fields and providing new strategies for achieving a balance between production and remediation in contaminated paddy fields.

Inhibiting release of phenanthrene from rice-crab coculture sediments to overlying water with rice stalk biochar: Performance and mechanisms

Rice crab coculture is a new ecological agriculture model combining rice cultivation and crab farming. Current research related to rice crab coculture only focuses on production theory and technical system establishment, while ignoring the potential ecological risk of Polycyclic aromatic hydrocarbon(PAHs) in rice crab coculture sediment. In this study, rice straw was used to make rice straw biochar to explore the performance and mechanism of inhibiting release of phenanthrene(PHE) from rice-crab coculture sediments to overlying water with rice stalk biochar. The kinetic and isotherm adsorption data were best represented by the Langmuir model and pseudo-second-order model with a maximum adsorption capacity of 53.35 mg/g at 12 h contact time. The results showed that PHE was released from the rice-crab substrate to the overlying water in dissolved and particle forms as a result of bioturbation, and the PHE concentrations in dissolved and particle forms were 20.9 μg/L and 14.22 μg/L, respectively. This leads to secondary ecological risks in rice-crab co-culture systems. This is related to dissolved organic carbon(DOC) carrying the dissolved PHE and total suspended solids(TSS) carrying the particle PHE in the overlying water. Due to its large specific surface area, rice straw biochar is rich in functional groups, providing multiple hydrophobic adsorption sites. After adding rice straw biochar at 0.5 % w/w (dry weight) dose, the removal efficiency of dissolved and particulate PHE in the overlying water were 78.99 % and 42.11 %, respectively. Rice straw biochar is more competitively adsorbed PHE in the overlying water than TSS and DOC. The removal efficiency of PHE from the sediment was 52.75 %. This study confirmed that rice stalk biochar could effectively inhibit PHE migration and release in paddy sediment. It provides an environment- friendly in situ remediation method for the management of PAHs pollution from crab crops in rice fields.

Bioconcentration of polycyclic aromatic hydrocarbons in different tissues of zebrafish (Danio rerio) investigated with PBTK model.

Due to the lipophilicity, polycyclic aromatic hydrocarbons (PAHs) are easily accumulated in fish. However, the research on PAH bioaccumulation process in different fish tissues and the relevant effect mechanisms are still deficient. The bioconcentration of PAHs (phenanthrene, anthracene, fluoranthene, and pyrene) in different zebrafish tissues (skin, fish muscle, gill, digestive tract, liver, gonad, and residual) was studied. It was found that there was a difference in the PAH concentrations in different zebrafish tissues. Compared with other tissues, the PAH concentration was highest in the skin and lowest in the fish muscle. For example, the steady-state concentration of phenanthrene in the skin was nearly five times higher than that in the muscle. PAH distribution was related with the lipid contents in different zebrafish tissues; however, the correlation was not significant (p > 0.05), indicating that the lipid content was not the determining factor for the PAH distribution. The distribution was also affected by the bioconcentration kinetics of PAHs in different zebrafish tissues, and the PAH hydrophobic properties. In addition, the physiological based toxicokinetic (PBTK) model showed good performance in predicting PAH internal concentrations, and it may be used to predict the concentrations of PAHs in different fish tissues in future.

Investigating the integration of physical-electrochemical-biological processes in the rehabilitation of dead soils contaminated with lead and phenanthrene

<p>This study was carried out with the aim of using three processes of soil washing, electrofenton and biological leaching method in order to rehabilitate the soil contaminated with lead and phenanthrene around the south Tehran oil refinery. The variables examined in this study are the amount of soil (500, 1000, 1500, 2000 mg), the ratio of surfactant to soil (7.50, 15, 22.50, 30, 37.50 L/Kg), time (6, 12, 18, 24, 30 hours), lead concentration (25, 50, 37.50, 62.50 mg/kg) and phenanthrene concentration (50, 100, 15, 200 mg/kg). In the washing process, the highest percentage of lead removal is 78.23% at the contact surface of 2000 mg, the surfactant-to-soil ratio is 30 ml/kg, the time is 24 hours, the concentration of lead and phenanthrene is 50 and 100 mg/kg and the highest removal percentage of phenanthrene (73.4%) in the soil amount of 1000 mg, the ratio of soil to surfactant equal to 30 liters/kg, in 12 hours, the amount of lead and phenanthrene were obtained equal to 25 and 100 mg/kg. Next, the soil was placed in a discontinuous reactor with graphene electrode as cathode and iron electrode as anode to conduct electrofenton. The investigated variables are solution pH (2, 4, 6, 8, 10), reaction time (12.5, 25, 37.5, 50, 62.5 minutes), hydrogen peroxide concentration (0.5, 1, 1.5, 2, 2.5 w/w) and direct electric current (0.75, 1.5, 2.25, 3, 3.75 A). The results indicated that in the electrofenton pH process, hydrogen peroxide concentration and then voltage had the greatest effect and time had the least effect on the removal of lead and phenanthrene. In this way, the highest percentage of lead removal was 85.4% at pH equal to 8, hydrogen peroxide concentration equal to 2 W/W, current equal to 1.5 A and 50 minutes and the highest percentage of phenanthrene removal (85.9%) at pH equal to 6, hydrogen peroxide concentration equal to 1.5W/W, current equal to 2.25 A and 37.5 minutes were obtained. In the biological leaching method, the purified strain (Pseudomonas aeruginosa) was isolated from the soils around the refinery. Environmental pH (3, 5, 7, 9, 11), pollutant to biomass ratio (7.50, 15, 22.50, 30, 37.5 mg/g) and retention time (1, 2, 3, 4, 5 hour) were considered as main variables. pH was the most important parameter influencing the removal of lead and phenanthrene from soil in biological method. The highest percentage of lead removal with 85.4% was obtained at pH equal to 8, hydrogen peroxide concentration equal to 2W/W, current 1.5 A and 50 minutes time. In the case of phenanthrene, the highest removal percentage of phenanthrene (85.9%) was measured at pH equal to 6, hydrogen peroxide concentration of 1.5 W/W, current of 2.25 A and in 37.5 minutes. Comparing the results of the third stage of soil cleaning with the control sample without preparation steps with the removal percentage of 0.67 and 0.42 for lead and phenanthrene, shows the effect of the soil preparation process in order to improve the ability of bacteria to function and shows that by combining three methods of washing, electrofenton and biologic, it is possible to rehabilitate contaminated soils resistant to biological decomposition.</p>

Effect of elevated temperature, sea water acidification, and phenanthrene on the expression of genes involved in the shell and pearl formation of economic pearl oyster (Pinctada radiata)

Our study aims to examine the effect of some stressors on the gene expression levels of shell matrix proteins in a pearl oyster. Oysters were exposed to the different combinations of the temperature, pH, and phenanthrene concentration is currently measured in the Persian Gulf and the predicted ocean warming and acidification for 28 days. The expression of all the studied genes was significantly downregulated. Time and temperature had the greatest effects on the decreases in n19 and n16 genes expression, respectively. Aspein and msi60 genes expression were highly influenced by pH. Pearlin was affected by double interaction temperature and phenanthrene. Moreover, a correlation was observed among the expression levels of studied genes. This study represents basic data on the relationship between mRNA transcription genes involved in the shell and pearl formation and climate changes in pollutant presence conditions and acclimatizing mechanism of the oyster to the future scenario as well.

Evaluation of Azolla filiculoides potential in pyrene and phenanthrene accumulation and phytoremediation in contaminated waters

Polycyclic aromatic hydrocarbons (PAHs) are a serious threat to the health of the environment. This study investigated the potential of Azolla filiculoides for the uptake, accumulation, and biodegradation of phenanthrene and pyrene. A- filiculoides plants were treated with 10 and 30 mg L−1 concentrations of phenanthrene and pyrene for the experimental duration of ten days. Phenanthrene and pyrene concentrations were measured using the high-performance liquid chromatography (HPLC) technique. Identification of the intermediate by-products resulting from the biological degradation of PAHs was performed by gas chromatography-mass spectrometry (GC/MS). The quantities of phenanthrene and pyrene in the ten-day treatments with 10 and 30 mg L−1 were 0.007 and 0.011 mg g−1 FW, and 0.048 and 0.079 mg g−1 FW, respectively. The growth parameters in the plants such as fresh weight, dry weight and RFN as well as the content of photosynthetic pigment of the plant decreased significantly compared to the control sample (p < 0.05). Ten compounds were identified from the plant tissue during the decomposition of pyrene and phenanthrene, and none of the PAHs were identified in the aquatic environment. Therefore, the use of A-filiculoides for phytoremediation of water resources contaminated with PAHs is an effective and promising method.

Polycyclic aromatic hydrocarbons: Measuring the air quality of three communities in Port Harcourt, Rivers State

There are a good number of major oil-producing companies as well as numerous activities that involve the combustion of organic matter. These activities release enormous quantities of pollutants into the atmosphere and there seems to be a paucity of data that captures the concentration of pollutants in the air as well as their health implications. This study was aimed at determining the levels/concentrations of polycyclic aromatic hydrocarbons in the surrounding air of three communities in Port Harcourt, Rivers State. Rivers State houses two oil refineries, a fertilizer company, and numerous companies. Sampling was conducted using the EGASPIN 2018 sampling procedure. Air samples were collected unto sterilized filter paper from the three communities using a Bosean meter. Sample extraction and analysis were conducted using GC-FID (EPA 8270). The study was conducted over the dry and wet seasons in 2019. Dry season result showed the presence of majorly four low molecular weight polycyclic aromatic hydrocarbons - naphthalene, fluorene, phenanthrene, and anthracene; in Okrika, concentrations of were 2.766±1.429 mg/kg, 0.976±0.491 mg/kg, 0.014±0.007 mg/kg and 0.040±0.023 mg/kg respectively; in Mgbuodohia the concentrations were 0.822±0.668 mg/kg, 1.199±0.626 mg/kg, 0.008±0.004 mg/kg and 0.012±0.009 mg/kg respectively; in Chokocho the concentrations were 0.144±0.097 mg/kg, 1.074±0.738 mg/kg, 0.001±0.000 mg/kg, and 0.142±0.067 mg/kg respectively. Wet season results showed the concentration of naphthalene, fluorene, phenanthrene, and anthracene; in Okrika, the concentration was 0.271±0.034 mg/kg, 0.108±0.019 mg/kg, 0.055±0.009 mg/kg and 0.001±0.000 mg/kg respectively; in Mgbuodohia the concentrations were 0.014±0.002 mg/kg, 0.005±0.004 mg/kg, 0.009±0.002 mg/kg and 0.001±0.000 mg/kg respectively; in Chokocho the concentrations were 0.001±0.000 mg/kg, 0.001±0.000 mg/kg, 0.002±0.001 mg/kg and 0.001±0.000 mg/kg. Against the backdrop of past studies linking the concentration of PAHs to the presence of refineries and other anthropogenic human activities, the Chokocho study location was chosen as a control site. The result agrees with the premise that air around regions where there is relatively less human activity like the combustion of organic matter, tend to have lower concentration of polycyclic aromatic hydrocarbon content. The total concentrations of PAHs in the air during the dry season are 3.809 mg/kg, 2.045 mg/kg, and 1.375 mg/kg in Okrika, Mgbuodohia, and Chokocho respectively, showing Okrika to be the most polluted followed by Mgbuodohia and lastly Chokocho. Source apportionment points to petrogenic, pyrolytic, and other possible sources. The detection of just four out of the sixteen priority PAHs points to the fact that there seems to be more effect on other matrices like soil and water.

The quantum of polycyclic aromatic hydrocarbon in &lt;em&gt;Pyxicephalus edulis&lt;/em&gt; and sediments in Oluwa river, Igbekebo area, Ondo state, Nigeria

Polycyclic aromatic hydrocarbons (PAHs) are organic compounds composed of two or more fused aromatic rings. PAHs can be found in a variety of foods and beverages, including drinking water, vegetables, fruits, cereals, oils, seafood, and meats. The current study investigated the pollution levels of the quantum of polycyclic aromatic hydrocarbon in Pyxicephalus edulis and river sediments. Twenty-five sediment samples and male and female specimens of Pyxicephalus edulis were collected from Oluwa River near Igbekebo, Ondo State Nigeria. The sediment samples were then dried in the open air for three days while the identified frog species were dried separately for 6 hours at 105°C before being powdered. The physicochemical parameters of sediment samples examined using standard physical and chemical analytical techniques and polycyclic aromatic hydrocarbons in frog and sediment samples were examined using gas chromatographyflame ionization analysis (GC-FID). The toxicity equivalent(TEQ) values of PAHs in sediment samples were determined by comparing the findings of this study to the Sediment Quality Guideline (SQG) with effects range from viz., low (ERL), median(ERM) and threshold-effects level (TEL)/probable-effects level (PEL) to assess the toxicity of PAHs to aquatic organisms living in sediments. Male frogs had significantly higher concentrations of Acenaphthylene, Phenanthrene, Anthracene, Pyrene, and total PAHs than females, and lower concentrations of Naphthalene, Acenaphthylene, Fluorene, and Fluoranthene. BaAnt, Benzo(b) fluoranthene, Benzo(k)fluoranthrene, Benzo(a)pyrene, Indeno(1,2,3-cd) pyrene, Dibenz(a,h)anthracene, Benzo(g,h,i)perylene were reported only among males. The cause of this variation is unknown, but it could be due to differences in the genetic make-up of male and female frogs.

Observations of atmospheric new particle formation impacts on cloud condensation nuclei in summer at Mt.Tian

As one of the important sources of aerosols, new particle formation events can affect the spatiotemporal distribution of CCN. To analyze the characteristics of new particle formation (NPF) events and their effects on cloud condensation nuclei (CCN) during the summer at Mt.Tian, the data of aerosol size distribution and CCN number concentrations were measured using an aerosol wide-range particle size spectrometer and a cloud condensation nuclei counter from August 4 to 25, 2019, and combined with meteorological data and polycyclic aromatic hydrocarbons (PAHs) data. NPF events at Mt.Tian occurred seven days during the observation period, accounting for 32% of the observation days, and usually occurred at 13:00 and ended at 17:00 (Beijing Time, same below). NPF events particularly influenced the diurnal variations of aerosol number concentrations in different modes. The number concentrations of nucleation and Aitken modes increased rapidly while the accumulation mode increased slowly during 13:00 and 17:00 on NPF days. The peak particle number concentrations in the nucleation, Aitken and accumulation modes on NPF days were 5360.1 cm−3, 7185.6 cm−3 and 839.3 cm−3, respectively, which were 3.3, 1.8 and 1.7 times higher than those on non-NPF days during 13:00 and 17:00. The meteorological conditions of temperature higher than 20 °C, air pressure lower than 806 hPa, relative humidity (RH) lower than 40% and wind speed higher than 2.2 m s−1 are favorable for the occurrence of NPF events. The NPF events at Mt.Tian can impact the mass concentration of PAHs. More Fluoride (FL) and Phenanthrene (PHE) were generated on NPF days. The mass concentrations of FL and PHE on NPF days were 0.002 ± 0.003 ng m−3 and 0.020 ± 0.010 ng m−3, which were 243.54% and 28.44% higher than those on non-NPF days, respectively. NPF events were conducive to increased CCN concentration at Mt.Tian. After the NPF events, the mean number concentrations of CCN at each supersaturation (SS) on NPF days was about 20%–50% higher than on non-NPF days. The contribution of NPF events to the CCN number concentrations was 35.75%, 28.56%, 44.15%, 42.11% and 29.12% at 0.1%, 0.2%, 0.4%, 0.6% and 0.8% SS, respectively.