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Concept: Fluoranthene

151

The analysis of polycyclic aromatic hydrocarbons (PAH) in ambient air requires the tedious experimental steps of both sampling and pretreatment (e.g., extraction or clean-up). To replace pre-existing conventional methods, a simple, rapid, and novel technique was developed to measure gas-particle fractionation of PAH in ambient air based on ‘sorbent tube-thermal desorption-gas chromatograph-mass spectrometer (ST-TD-GC-MS)’. The separate collection and analysis of ambient PAHs were achieved independently by two serially connected STs. The basic quality assurance confirmed good linearity, precision, and high sensitivity to eliminate the need for complicated pretreatment procedures with the detection limit (16 PAHs: 13.1 ± 7.04 pg). The analysis of real ambient PAH samples showed a clear fractionation between gas (two-three ringed PAHs) and particulate phases (five-six ringed PAHs). In contrast, for intermediate (four ringed) PAHs (fluoranthene, pyrene, benz[a]anthracene, and chrysene), a highly systematic/gradual fractionation was established. It thus suggests a promising role of ST-TD-GC-MS as measurement system in acquiring a reliable database of airborne PAH.

Concepts: Benzene, Chrysene, Aromaticity, Fluoranthene, Naphthalene, Pyrene, Measurement, Polycyclic aromatic hydrocarbon

28

Concentrations of 22 polycyclic aromatic hydrocarbons (PAHs) were estimated for individual particle-size distributions at the airport apron of the Taipei International Airport, Taiwan, on 48 days in July, September, October, and December of 2011. In total, 672 integrated air samples were collected using a micro-orifice uniform deposition impactor (MOUDI) and a nano-MOUDI. Particle-bound PAHs (P-PAHs) were analyzed by gas chromatography with mass selective detector (GC/MSD). The five most abundant species of P-PAHs on all sampling days were naphthalene (NaP), phenanthrene (PA), fluoranthene (FL), acenaphthene (AcP), and pyrene (Pyr). Total P-PAHs concentrations were 152.21, 184.83, and 188.94 ng/m(3) in summer, autumn, and winter, respectively. On average, the most abundant fractions of benzo[a]pyrene equivalent concentration (BaPeq) in different molecular weights were high-weight PAHs (79.29 %), followed by medium-weight PAHs (11.57 %) and low-weight PAHs (9.14 %). The mean BaPeq concentrations were 1.25 and 0.94 (ng/m(3)) in ultrafine particles (<0.1 μm) and nano-particles (<0.032 μm), respectively. The percentages of total BaPeq in nano- and ultrafine particulate size ranges were 52.4 % and 70.15 %, respectively.

Concepts: Phenanthrene, Fluoranthene, Polycyclic aromatic hydrocarbons, Airport, Aromaticity, Naphthalene, Pyrene, Polycyclic aromatic hydrocarbon

28

The arenium acid [mesitylene-H]+ has been shown to be an extraordinarily active H/D exchange catalyst for the perdeuteration of polycyclic aromatic hydrocarbons. The reactions take place under ambient conditions in C6D6 as an inexpensive deuterium source. High isolated yields and excellent degrees of deuterium incorporation were achieved using the substrates para-terphenyl, fluoranthene, pyrene, triphenylene, and corannulene.

Concepts: Organic chemistry, Fluoranthene, Benzene, Aromatic hydrocarbon, Pyrene, Hydrogen, Polycyclic aromatic hydrocarbons, Polycyclic aromatic hydrocarbon

22

Hydrophobic organic compounds (HOCs) tend to be associated with suspended particles in surface aquatic systems, however, the bioavailability of HOCs on suspended particles to fish is not well understood. In this study, a passive dosing device was used to control the freely dissolved concentrations (Cfree) of polycyclic aromatic hydrocarbons (PAHs) including fluoranthene and pyrene, and the influence of particle-associated PAHs on their bioaccumulation by zebrafish was investigated. The results showed that, when the Cfreeof PAHs were kept constant, the presence of suspended particles did not significantly affect the steady state of PAH bioaccumulation in zebrafish tissues excluding head and digestive tracts, suggesting that the bioaccumulation steady state was controlled by the freely dissolved concentrations of PAHs. However, suspended particles promoted the uptake and elimination rate constants of PAHs in zebrafish body excluding head and digestive tracts. The uptake rate constants with 0.5 g/L suspended particles were approximately twice of those without suspended particles, and the body burden in zebrafish increased by 16.4% - 109.3% for pyrene and 21.8% - 490.4% for fluoranthene during the first 8-d exposure. This was due to the reasons that suspended particles could be ingested, and part of PAHs associated with them could be desorbed in digestive tract and absorbed by the zebfrafish, leading to the enhancement of uptake rates of PAHs in zebfrafish. The findings obtained from this study indicate that PAHs on suspended particles are partly bioavailable to zebrafish and particle ingestion is an important route in PAH bioaccumulation. Therefore, it is important to consider the bioavailability of HOCs on suspended particles to improve ecological risk assessment.

Concepts: Organic chemistry, Polycyclic aromatic hydrocarbons, Aromaticity, Digestive system, Fluoranthene, Digestion, Pyrene, Polycyclic aromatic hydrocarbon

0

Chlorinated polycyclic aromatic hydrocarbons (ClPAHs) are an emerging class of environmental contaminants, but the sources of ClPAHs in the environment are not well known. In this study, we developed a kinetic model describing the chlorination of PAHs to observe the mechanism of formation of ClPAHs during the combustion of organic waste containing chlorinated compounds and/or chloride in an incinerator. Pyrene (Pyr) and polyvinyl chloride (PVC) were selected as a model PAH and a model organic substrate, respectively. All combustion experiments were carried out using a model furnace under similar experimental conditions. Combustion of PVC in the model furnace produced 1-ClPyr, 1,3-Cl2Pyr, 1,6-Cl2Pyr, 1,8-Cl2Pyr, 1,3,6-Cl3Pyr, and 1,3,6,8-Cl4Pyr. The developed model supported the experimental data on the sequential chlorination of pyrene. The rate constants for the formation of mono- to tri-chlorinated pyrenes were over 30 times those for the formation of tetra- and penta-chlorinated pyrenes. A qualitative analysis of the formation of highly chlorinated pyrenes based on a comparison of theoretical and empirical isotopic patterns of the mass spectrum revealed that penta- and hexa-chlorinated pyrenes, whose analytical standards were not available, were also produced by the combustion of PVC.

Concepts: Aromaticity, Polyvinyl chloride, Polycyclic aromatic hydrocarbons, Fluoranthene, Plastic, Pyrene, Scientific method, Polycyclic aromatic hydrocarbon

0

The biodegradation of polycyclic aromatic hydrocarbons (PAHs) by marine-derived fungi was reported in this work. Marine-derived fungi (Trichoderma harzianum CBMAI 1677, Cladosporium sp. CBMAI 1237, Aspergillus sydowii CBMAI 935, Penicillium citrinum CBMAI 1186 and Mucor racemosus CBMAI 847) biodegraded anthracene (14days, 130rpm, 50mgmL(-1) initial concentration in malt 2% medium). Cladosporium sp. CBMAI 1237 was the most efficient strain and biodegraded more anthracene in the presence (42% biodegradation) than in the absence (26%) of artificial seawater, suggesting that the biodegradation of PAHs may be faster in seawater than in non-saline environment. After 21days, Cladosporium sp. CBMAI 1237 biodegraded anthracene (71% biodegradation), anthrone (100%), anthraquinone (32%), acenaphthene (78%), fluorene (70%), phenanthrene (47%), fluoranthene (52%), pyrene (62%) and nitropyrene (64%). Previous undocumented metabolites were identified and, anthraquinone was a common product of different PAHs biodegradation. The marine-derived fungus Cladosporium sp. CBMAI 1237 showed potential for bioremediation of PAHs.

Concepts: Fungus, Fluoranthene, Benzene, Polycyclic aromatic hydrocarbons, Pyrene, Phenanthrene, Anthracene, Polycyclic aromatic hydrocarbon

0

Atmospheric deposition leads to accumulation of atmospheric polycyclic aromatic hydrocarbons (PAHs) on urban surfaces and topsoils. To capture the inherent variability of atmospheric deposition of PAHs in Shanghai’s urban agglomeration, 85 atmospheric bulk deposition samples and 7 surface soil samples were collected from seven sampling locations during 2012-2014. Total fluxes of 17 PAHs were 587-32,300 ng m(-2) day(-1), with a geometric mean of 2600 ng m(-2) day(-1). The deposition fluxes were categorized as moderate to high on a global scale. Phenanthrene, fluoranthene and pyrene were major contributors. The spatial distribution of deposition fluxes revealed the influence of urbanization/industrialization and the relevance of local emissions. Meteorological conditions and more heating demand in cold season lead to a significant increase of deposition rates. Atmospheric deposition is the principal pathway of PAHs input to topsoils and the annual deposition load in Shanghai amounts to ∼4.5 tons (0.7 kg km(-2)) with a range of 2.5-10 tons (0.4-1.6 kg km(-2)).

Concepts: Anthracene, Polycyclic aromatic hydrocarbons, Phenanthrene, Aromaticity, Fluoranthene, Naphthalene, Pyrene, Polycyclic aromatic hydrocarbon

0

In this study, a tiny coiled cupper wire as a novel solid phase microextraction (SPME) fiber was coated with mesoporous silica/cetyltrimethylammonium bromide (MCM-41/CTAB) as an adsorbent by electrochemically assisted self-assembly method and used for the preconcentration of polycyclic aromatic hydrocarbons (PAHs) as model analytes prior to chromatographic determination. Deposition of MCM-41/CTAB on the coiled SPME (C-SPME) fiber resulted in easily controlled and reproducible SPME coatings. Non-calcined MCM-41/CTAB on C-SPME plays a key role in the adsorption of PAHs. Under the optimized experimental conditions, low detection limits (36-1220pgL(-1)), and wide linear dynamic ranges (R(2)>0.98) were achieved in the range of 0.25-25,000, 0.12-15,000, 0.56-32,000, 4.1-100,000ngL(-1) for phenanthrene, anthracene, fluoranthene and pyrene respectively. The reusability of proposed fiber as well as relative standard deviations for repetitive determination of the target analytes was evaluated. The proposed method was successfully applied for determination of PAHs in several real samples.

Concepts: Aromaticity, Solid phase microextraction, Fluoranthene, Ice, Phenanthrene, Anthracene, Pyrene, Polycyclic aromatic hydrocarbon

0

Ring-hydroxylating dioxygenases (RHDs) play a critical role in the biodegradation of polycyclic aromatic hydrocarbons (PAHs). In this study, genes pdoAB encoding a dioxygenase capable of oxidizing various PAHs with up to five-ring benzo[a]pyrene were cloned from Mycobacterium sp. NJS-P. The α-subunit of the PdoAB showed 99% and 93% identity to that from Mycobacterium sp. S65 and Mycobacterium sp. py136, respectively. An Escherichia coli expression experiment revealed that the enzyme is able to oxidize anthracene, phenanthrene, pyrene and benzo[a]pyrene, but not to fluoranthene and benzo[a]anthracene. Furthermore, the results of in silico analysis showed that PdoAB has a large substrate-binding pocket satisfying for accommodation of HMW PAHs, and suggested that the binding energy of intermolecular interaction may predict the substrate conversion of RHDs towards HMW PAHs, especially those may have steric constraints on the substrate-binding pocket, such as benzo[a]pyrene and benzo[a]anthracene.

Concepts: Fluoranthene, Carbon, Naphthalene, Enzyme, Phenanthrene, Anthracene, Pyrene, Polycyclic aromatic hydrocarbon

0

A new design strategy to activate aggregation-induced emission (AIE) in pyrene chromophores is reported. In a previous report, we demonstrated that highly twisted N,N-dialkylamines of anthracene and naphthalene induce drastic AIE when these donors are introduced at appropriate positions to stabilize the S1/S0 minimum energy conical intersection (MECI). In the present study, this design strategy was applied to pyrene: the introduction of N,N-dimethylamine substituents at the 4,5-positions of pyrene, the so-called K-region, are likely to stabilize MECIs. To examine this hypothesis, four novel pyrene derivatives, which contain highly twisted N,N-dimethylamino groups at the 4- (4-Py), 4,5- (4,5-Py), 1- (1-Py), or 1,6-positions (1,6-Py) were tested. The nonradiative transitions of 4,5-Py are highly efficient (knr = 57.1 × 10(7) s(-1)), so that its fluorescence quantum yield in acetonitrile decreases to Φfl = 0.04. The solid-state fluorescence of 4,5-Py is efficient (Φfl = 0.49). In contrast, 1,6-Py features strong fluorescence (Φfl = 0.48) with a slow nonradiative transition (knr = 11.0 × 10(7) s(-1)) that is subject to severe quenching (Φfl = 0.03) in the solid state. These results underline that the chemistry of the pyrene K-region is intriguing, both from a photophysical perspective and with respect to materials science.

Concepts: Vacuum tube, Fluoranthene, Pyrene, Introduction, Polycyclic aromatic hydrocarbon, Electron, Fluorescence