Abstract  The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) section 104 (i), as amended by the Superfund Amendments and Reauthorization Act (SARA), requires ATSDR and the EPA to prepare a list, in order of priority, of substances that are most commonly found at facilities on the National Priorities List (NPL) and which are determined to pose the most significant potential threat to human health due to their known or suspected toxicity and potential for human exposure at these NPL sites. CERCLA also requires this list to be revised periodically to reflect additional information on hazardous substances. In CERCLA, it is called the priority list of hazardous substances that will be candidates for toxicological profiles. This substance priority list is revised and published on a 2-year basis, with a yearly informal review and revision. (No list was published in 2009 while ATSDR transitioned to a new agency science database.) Each substance on the list is a candidate to become the subject of a toxicological profile prepared by ATSDR. The listing algorithm prioritizes substances based on frequency of occurrence at NPL sites, toxicity, and potential for human exposure to the substances found at NPL sites.

Abstract  Polycyclic aromatic hydrocarbons (PAHs) are complex hazardous organic compounds that are introduced into the atmosphere as by-products of partial combustion processes. For common atmospheric conditions, the large molecular weight PAHs, such as benzo(a)pyrene (B[a]P), are found in the particulate phase and are believed to account for a considerable amount of the fine particulate matter toxic potential. Nonetheless, unlike meteorological variables and criteria pollutants, PAHs are very rarely monitored on a routine basis in most parts of the world. We present methodology for development and evaluation of a model for estimation of daily and monthly ambient B[a]P concentrations. The model utilizes a very large ambient B[a]P database from three sites in the Czech Republic. The difficulties faced when dealing with ambient PAH data are discussed. Model performance was evaluated by a complete internal-, external-, and temporal cross validations. The models reproduced very accurately monthly mean ambient B[a]P concentrations and provided acceptable daily mean B[a]P, concentrations. Spatial extrapolations resulted in small deterioration of the models' performance. The temporal backward extrapolation revealed comparable errors to the spatial extrapolations in spite of the dramatic emissions reduction in the early years of the study period. (C) 2014 Elsevier Ltd. All rights reserved.

Abstract  OBJECTIVES: In order to assess the potential carcinogenic and genotoxic responses induced by environmental pollutants, genotoxicity test systems based on a GADD45α promoter-driven luciferase reporter in human A549 and HepG2 cells were established.

MATERIALS AND METHODS: Four different types of environmental toxicants including DNA alkylating agents, precarcinogenic agents, DNA cross-linking agents and non-carcinogenic agents, and three environmental samples collected from a coke oven plant were used to evaluate the test systems. After treated with the tested agents and environmental samples for 12 h, the cell viabilities and luciferase activities of the luciferase reporter cells were determined, respectively.

RESULTS: Methyl methanesulfonate, benzo[a]pyrene, formaldehyde and the extractable organic matter (EOM) from coke oven emissions in ambient air generally produced significant induction of relative luciferase activity in a similar dose-dependent manner in A549- and HepG2-luciferase cells. No significant increases in relative luciferase activity were observed in pyrene-treated A549- or HepG2-luciferase cells. Significant increase in relative luciferase activity was already evident after 2.5 µM benzo[a]pyrene, 5 µM formaldehyde, 0.006 µg/L bottom-EOM, 0.10 µg/L side-EOM or 0.06 µg/L top-EOM, where no cytotoxic damage was observed. Compared with the A549-luciferase cells, the tested pollutants produced higher induction of relative luciferase activity in HepG2-luciferase cells.

DISCUSSION AND CONCLUSION: Therefore, the new genotoxicity test systems can detect different types of genotoxic agents and low concentrations of environmental samples. The luciferase reporter cells, especially the HepG2-luciferase cells, could provide a valuable tool for rapid screening of the genotoxic damage of environmental pollutants and their complex mixtures.

Abstract  Lichens, symbioses of fungi and algae and/or cyanobacteria, have the remarkable ability to uptake and accumulate semivolatile organic compounds (SVOC) from air, including polycyclic aromatic hydrocarbons (PAHs), but the mechanism of accumulation is still unknown. Understanding these mechanisms is critical to standardize the use of lichens as environmental bioindicators and to further integrate them in air monitoring networks. Through a series of experiments we show that gas phase PAHs easily cross lichen's surface and accumulate in the photosynthetic algal layer of lichens. Once accumulated, they remain in the algal layer and not within the fungus hyphae, or adhered to lichen's surface, as it was previously supposed to happen. Additionally, when lichens are washed, gas phase PAHs still remain in the algal layer. Our results reveal that lichens may be utilized as bioindicators of gas phase PAHs, overcoming current limitations of air monitoring.

Abstract  This study provides experimental evidence that di(1-pyrenylmethyl) ether or DiPyMe, a well-known fluorescent probe employed to determine the microviscosity of surfactant or polymeric micelles, is being hydrolyzed in the presence of water upon UV irradiation. This effect was established from a careful analysis of the fluorescence spectra and decays acquired with aqueous solutions of DiPyMe dissolved in micelles of sodium dodecyl sulfate (SDS). The size of the SDS micelles could be adjusted from an aggregation number (N-agg) of 70 to 172 by increasing the ionic strength of the aqueous solution from 0.0 to 0.5 M NaCl. The hydrolysis of DiPyMe was much reduced in the larger SDS micelles. While the degradation of DiPyMe in aqueous solutions of SDS micelles affected the analysis of the fluorescence spectra, model-free analysis (MFA) of the fluorescence decays of DiPyMe could reliably retrieve the rate constant < k > of excimer formation for DiPyMe. After calibration with mixtures of organic solvents of known macroscopic viscosity, the < k > values obtained for DiPyMe yielded the microviscosity (mu eta) of the SDS micelles as a function of salt concentration. The mu eta was found to increase from 4.0 to 8.8 mPa.s as the salt concentration increased from 0.0 to 0.5 M. This study demonstrated that, regardless of the problem of its hydrolysis that jeopardizes its use in steady-state fluorescence experiments, DiPyMe remains an extremely valuable probe for describing the microviscosity of hydrophobic domains in aqueous solution as long as its decays are analyzed with a model that accounts for the presence of degradation products as the MFA does.

Abstract  This study has investigated the use of screened maize for remediation of soil contaminated with crude oil. Pots experiment was carried out for 60days by transplanting maize seedlings into spiked soils. The results showed that certain amount of crude oil in soil (<= 2 147mg.kg(-1)) could enhance the production of shoot biomass of maize. Higher concentration (6 373mg.kg(-1)) did not significantly inhibit the growth of plant maize (including shoot and root). Analysis of plant shoot by GC-MS showed that low molecular weight polycyclic aromatic hydrocarbons (PAHs) were detected in maize tissues, but PAHs concentration in the plant did not increase with higher concentration of crude oil in soil. The reduction of total petroleum hydrocarbon in planted soil was up to 52.21-72.84%, while that of the corresponding controls was only 25.85-34.22% in two months. In addition, data from physiological and biochemical indexes demonstrated a favorable adaptability of maize to crude oil pollution stress. This study suggested that the use of maize (Zeamays L.) was a good choice for remediation of soil contaminated with petroleum within a certain range of concentrations.

Abstract  Plants are autotrophic organisms which are able to use sunlight and carbon dioxide as the sources of energy and carbon. Plants' roots absorb a range of natural and anthropogenic toxic compounds for which they have developed some extraordinary detoxification mechanisms. From this point of view, plants can be seen as natural, solar-powered pump-and-treat systems for cleaning up contaminated soils, leading further to the concept of phytoremediation. The phytoremediation of polycyclic aromatic hydrocarbons (PAHs) refers to the use of plants and associated soil microorganisms in terms of reducing the concentrations or toxic effects of these contaminants in the environment. Although there is little evidence to prove that PAHs from soils are accumulated considerably in plants' parts, there is a lot of evidence that in soils vegetated with grasses and legumes, a significant dissipation of PAHs occurs. Namely, the primary mechanism controlling this process is the rhizospheric microbial degradation, where soil microbial populations use organic compounds as carbon substrates for its growth. This is usually stimulated by roots exudates. The final result of this process is the breakdown and eventual total mineralization of the contaminants. The main challenge in PAH phytoremediation is to improve the performances of plants and rhizospheric microorganisms requiring thus more basic research and knowledge on natural detoxification mechanisms.

Abstract  Airborne fine particulate matter PM2.5 was collected from May 2010 to December 2012 at Agra, a semi-urban site in north-central India. PM2.5 samples were chemically characterized for 16 polycyclic aromatic hydrocarbons by gas chromatography. PM2.5 values varied between 8.4 and 300 µg m(-3) with 55% of the values exceeding the 24h average NAAQ (National Ambient Air Quality) standard of 65 µg m(-3). Particle associated total PAHs ranged between 8.9 and 2,065 ng m(-3) with a mean value of 880.8 ng m(-3) during the sampling period, indicated an alarming level of pollution in Agra. Strong relationship was observed between PM2.5 and total PAHs (r=0.88), suggesting an increasing PAHs concentration with increasing PM2.5 mass. On a mass basis 3-ring and 4-ring compounds were dominant. Seasonal variation in mass concentration of PAHs was observed with high concentration in winter followed by post monsoon, summer and monsoon. This seasonal pattern could be attributed to differences in source strength and climatic conditions. PAHs concentration were also observed to be negatively correlated with the meteorological parameters i.e. temperature, solar radiation, relative humidity and wind speed. Molecular diagnostic ratios revealed vehicular emissions and combustion of wood and coal as the probable sources. The estimated carcinogenicity of PAHs in terms of benzo(a)pyrene toxic equivalency (B[a]PTEQ) was assessed and confirmed that benzo[a]pyrene was the dominant PAH contributor (3.64%). Health risk of adults and children by way of PAHs was assessed by estimating the lifetime average daily dose (LADD) and corresponding incremental lifetime cancer risk (ILCR) using USEPA guidelines. The assessed cancer risk (ILCR) was found to be within the acceptable range (10(-6)-10(-4)). The particulate samples indicated the presence of both base pair and frame shift mutagens using TA98 and TA100 strains of Salmonella typhimurium. Enhanced mutagenic response was observed in the presence of enzyme activation.

Abstract  In Colombia little attention has been paid to river pollution with Polycyclic Aromatic Hydrocarbons (PAHs). Low environmental control and legislation in such emerging region could significantly contribute to high PAHs releases. In this study, we report the presence of PAHs in water and sediments of the Cauca River (Colombia). Three sampling campaigns were carried out between May 2010 and June 2011, and the samples were collected at eight relevant sites. The sampling time included measuring before, during, and after a season of heavy rains, which were influenced by the global coupled ocean-atmospheric phenomenon, which affected tropical countries with huge flooding, commonly called "La Niña", and/or "El Niño" Southern Oscillation (ENSO). The highest mean ∑PAH concentrations were 4476.5ng/l and 1582.7ng/g in water and sediments, respectively. The PAHs most detected were Benzo[b]fluoranthene, Benzo[k]fluoranthene, and Pyrene in sediments; and Fluorene, Acenaphtylene, and Anthracene in water. After the season of rains statistically significant higher PAH concentrations were detected. The results of the study were compared to other rivers worldwide at both environmental compartments, and did not show concentrations of special concern. In some sites, concentrations detected of PAHs were higher than screening benchmarks for ecological protection. Estimation of human health risks was carried out, and the results suggested some likely carcinogenic effects due to PAHs especially in children exposed during current recreational swimming and adults working in low technology sand extraction.

Abstract  In the 1980s long-lived radical species were identified in cigarette tar. Since then, environmentally persistent free radicals (EPFRs) have been observed in ambient particulate matter, and have been generated in particulate matter generated from internal combustion engines. For the first time, we measure in situ the formation and decay of EPFRs through the heterogeneous reaction of ozone and several polycyclic aromatic compounds (PAC). Solid anthracene (ANT), pyrene (PY), benzo[a]pyrene (BAP), benzo[ghi]perylene (BGHIP), 1,4-naphthoquinone (1,4NQ), and 9,10-anthraquinone (AQ) were reacted with gas-phase ozone in a flow system placed in the active cavity of an electron paramagnetic resonance (EPR) spectrometer, and the formation of radicals was measured on the timescale of tens of minutes at ambient levels of ozone down to 30 ppb. For most substrates the net radical production is initially rapid, slows at intermediate times, and is followed by a slow decay. For oxidized solid BAP, radical signal persists for many days in the absence of ozone. To evaluate the effect of substrate phase, the solid PAHs were also dissolved in squalane, an organic oil inert to ozone, which yielded a much higher maximum radical concentration and faster radical decay when exposed to ozone. With higher mobility, reactants were apparently able to more easily diffuse and react with each other, yielding the higher radical concentrations. The EPR spectra exhibit three radicals types, two of which have been assigned to semiquinone species and one to a PAH-derived, carbon-centered radical. Although our system uses levels of PAC not typically found in the environment it is worth noting that the amounts of radical formed, on the order of 10(18) radicals per g, are comparable to those observed in ambient particulate matter.

Abstract  Benzo[a]pyrene (BaP) is a well-studied environmental compound that requires metabolic activation to have a carcinogenic effect. The neurotoxicity of BaP has received considerably less attention than its carcinogenicity. Environmental exposure to BaP correlates with impaired learning and memory in adults, and poor neurodevelopment in children. We carried out a comprehensive literature review to examine the neurotoxicity of BaP. The data were used to identify potential point of departure (POD) values for cancer and neurotoxicity endpoints using benchmark dose (BMD) modelling to compare the utility of both endpoints in the risk assessment of BaP. The POD for neurotoxicity in rodents, based on a standard behavioural test (Morris water maze), was 0.025 mg BaP/kg-bw-day compared to 0.54 mg BaP/kg-bw-day for rodent forestomach carcinogenicity, suggesting that neurotoxic endpoints are more sensitive than cancer endpoints for health risks associated with BaP exposure. Using the limited number of published studies on this topic, we propose a preliminary mode of action (MOA) to explain BaP-induced neurotoxicity in rodents. The MOA includes: (1) BaP binding to the aryl hydrocarbon receptor (AHR); (2) AHR-dependent modulation of the transcription of N-methyl-d-aspartate glutamate receptor (NMDAR) subunits; (3) NMDAR-mediated loss of neuronal activity and decreased long-term potentiation; and (4) compromised learning and memory. More data are needed to explore the proposed neurotoxic MOA. In addition, we consider alternative MOAs, including the hypothesis that BaP-mediated DNA damage may lead to either carcinogenicity or neurotoxicity, depending on the tissue. Our proposed MOA is intended to serve as a basis for hypothesis testing in future studies. We emphasise that further studies are needed to validate the proposed MOA, to evaluate its human relevance, and to explore other potential mechanisms of BaP neurotoxicity.

Abstract  The aim of the study was to determine extent, in which coagulation can affect to the risk reduction of human exposure to the consumption of water containing polycyclic aromatic hydrocarbons (PAHs). The paper presents results of research on the removal of priority PAHs (naphthalene, anthracene, fluoranthene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(g,h,i)perylene, and indeno(1,2,3-cd)pyrene) from water in the volumetric coagulation and sedimentation process. For analysis were chosen coagulants such as aluminum(VI)sulfate and two pre-hydrolyzed coagulantsPAX XL 19H and FLOKOR 1ASW/B. Water samples subjected to coagulation were collected from selected water treatment plant following the pre-ozonation process. Tested coagulants were dosed at optimal doses (2.8; 3.6mg Al3+/L). Summary concentration of eight hazardous PAHs in water after pre-ozonation amounted to 60.78ng/L. After volumetric coagulation using selected coagulants was in the range of 31.51-33.64ng/L. The highest efficiency in the removal of 8 PAHs was obtained after application of FLOKOR 1 ASW/B (48.2%). Also in the removal of benzo(a)pyrene FLOKOR 1ASW/B was the most effective (decrease by 89.9%). The risk analysis was carried out for five hydrocarbons: benzo(a)pyrene, benzo(b)fluoranthene and benzo(k)fluoranthene, benzo(g,h,i)perylene and indeno(1,2,3-cd)pyrene.

Abstract  A simple reverse phase high-performance liquid chromatographic method has been developed for determining the concentration of metformin in rat plasma. The method employs C(18) column (300 mm x 2.4 mm i.d.), ammonium acetate (0.15 M) and acetonitrile (90:10; pH-5.5; 1.0 ml/min) as mobile phase and ultraviolet detection at 236 nm. Acetonitrile was used to simultaneously deproteinize rat plasma and extract metformin. The assay was linear in the concentration range of 0.33 mug-16.6 mug/ml with co-efficient of correlation 0.994. The retention time was 4.7 min. The method was found to be precise (% CV < 15%), accurate and suitable for pharmacokinetic study of orally administered metformin in rats.

Abstract  On-site disposal of sewage in septic systems can lead to groundwater plumes with NO(3) (-) -N concentrations exceeding the common drinking water limit of 10 mg/L. Currently, denitrification is considered as the principal natural attenuation process. However, at a large seasonal-use septic system in Ontario (256 campsites), a suboxic zone exists where nitrogen removal of up to 80% occurs including removal of NH(4) (+) -N. This zone has both NO(3) (-) -N and NH(4) (+) -N at >5 mg/L each. In the distal NH(4) (+) -rich zone, NH(4) (+) -N concentrations (8.1 ± 8.0 mg/L) are lower than in the proximal zone (48 ± 36 mg/L) and NH(4) (+) -N is isotopically enriched (concentration-weighted mean δ(15) N of +15.7‰) compared to the proximal zone (+7.8‰). Furthermore, δ(15) N-NH(4) (+) isotopic enrichment increases with depth in the distal zone, which is opposite to what would result if nitrification along the water table zone was the mechanism causing NH(4) (+) depletion. Bacterial community composition was assessed with molecular (DNA-based) analysis and demonstrated that groundwater bacterial populations were predominantly composed of bacteria from two Candidatus genera of the Planctomycetales (Brocadia and Jettenia). Together, these data provide strong evidence that anaerobic ammonium oxidation (anammox) plays an important role in nitrogen attenuation at this site.

Abstract  The cation and the anion in the title salt, (C(6)H(16)N)[SnCl(4)(C(6)H(4)NO(2))], are linked by an N-H⋯O hydrogen bond. The Sn(IV) atom in the stannate anion is chelated by the pyridine-2-carboxyl-ate group and exists in a cis-SnCl(4)NO octa-hedral geometry. The cation is disordered over two positions in a 0.564 (1):0.436 (1) ratio.

Abstract  Perchlorate, a known thyroid disruptor, is deposited in eggs of exposed female birds, raising concerns that the embryos from these eggs may become hypothyroid, which may in turn affect the development and function of thyroid-dependent organs. We hypothesized that exposure to ammonium perchlorate (AP) would decrease hen and embryonic thyroid function and affect the expression of thyroid-responsive genes in embryonic brain and liver. Laying Japanese quail hens were treated with 2000 mg/l or 4000 mg/l AP in drinking water. Thyroid status and expression of thyroid-responsive genes were examined in the embryos from eggs of exposed hens. Perchlorate exposure led to hypothyroidism in hens from both treatment groups; egg production was decreased in the high dosage group only. Embryos from eggs of perchlorate-exposed hens had hypertrophied thyroid glands and significantly lower thyroidal hormone storage, indicating hypothyroidism in these embryos. The embryonic hypothyroidism was associated with decreased embryonic growth, delayed hatching and greater mortality during hatching. The mRNA level of type 2 deiodinase (D2) in the liver of embryos from eggs of perchlorate-exposed hens was increased compared to the control embryos, a compensatory response that increases the production of metabolically active T(3). However, the mRNA levels of D2 and RC3 in the brain were not affected. These results suggest that the embryonic brain is protected from hypothyroidism by other mechanisms known to influence hormone entry into and exit from the brain. Our study shows that maternal perchlorate exposure led to embryonic hypothyroidism and may have interfered with embryonic development.

Abstract  In the dication of the title salt, C(6)H(16)N(2) (2+)·2C(6)H(4)NO(2) (-), the two ammonium groups are in the equatorial positions of the chair-shaped cyclo-hexyl ring. In the crystal, the cations and anions are linked by N-H⋯O and N-H⋯N hydrogen bonds, forming a layer network parallel to the ac plane. Weak π-π inter-actions between adjacent pyridine rings with a centroid-centroid distance of 3.589 (2) Å are also present.

Abstract  Single-molecule PCR (SM-PCR) analysis of long and repetitive DNA sequences, known as expanded simple tandem repeats (ESTRs), has been the most efficient method for studying germline mutation induction in endogenous sequences to date. However, the long length of these sequences makes mutation detection imprecise and laborious, and they have been characterized only in mice. Here, we explore the use of unstable microsatellite sequences that can be typed with high precision by capillary electrophoresis as alternative loci for detecting germline mutations. We screened 24 microsatellite loci across inbred mouse strains and identified Mm2.2.1 as the most polymorphic microsatellite locus. We then optimized SM-PCR of Mm2.2.1 to detect mutations in sperm. SM-PCR analysis of sperm from untreated B6C3F1 and Muta (TM) Mouse samples revealed mutation frequencies that are consistent with rates derived from family pedigree analysis (similar to 5 x 10(-3)). To determine whether this locus can be used to detect chemically induced germline mutations, Muta (TM) Mouse males were exposed by oral gavage to a single dose of 100 mg/kg of N-ethyl-N-nitrosourea (ENU) or to 100 mg/kg of benzo(a)pyrene (BaP) for 28 days alongside vehicle treated controls. Sperm were collected 10 weeks post-ENU exposure to sample sperm exposed as spermatogonial stem cells and 6 weeks post-BaP exposure to sample sperm that were dividing spermatogonia when the exposure was terminated. Both treatments resulted in a significant (approximately 2-fold) increase in mutation frequency in sperm compared to the control animals. The work establishes the utility of this microsatellite for studying mutation induction in the germ cells of mice. Because microsatellites are found in virtually every species, this approach holds promise for other organisms, including humans. Crown Copyright (C) 2015 Published by Elsevier B.V.

Abstract  Diesel exhaust particles (DEP) and the associated complex mixtures of organic pollutants, such as polycyclic aromatic hydrocarbons (PAHs), or their derivatives, have been suggested to exert deleterious effects on human health. We used a set of defined cellular models representing liver, lung and prostate tissues, in order to compare non-genotoxic and genotoxic effects of crude and fractionated extract of a standard reference DEP material - SRM 1650b. We focused on the aryl hydrocarbon receptor (AhR)-mediated activity, modulation of cell proliferation, formation of DNA adducts, oxidative DNA damage, and induction of DNA damage responses, including evaluation of apoptosis, and phosphorylation of p53 tumor suppressor and checkpoint kinases (Chk). Both PAHs and the polar aromatic compounds contributed to the AhR-mediated activity of DEP-associated organic pollutants. The principal identified AhR agonists included benzo[k]fluoranthene, indeno[1,2,3-c,d]pyrene, chrysene and several non-priority PAHs, including benzochrysenes and methylated PAHs. In contrast to PAHs, polar compounds contributed more significantly to overall formation of DNA adducts associated with phosphorylation of p53, Chk1 or Chk2, and partly with apoptosis. Therefore, more attention should be paid to identification of DEP-associated polar organic compounds, contributing to the AhR activation and cytotoxic/genotoxic effects of complex airborne mixtures of organic contaminants produced by diesel engines.

Abstract  The repertoire of synthetic methods leading to aza-analogues of polycyclic aromatic heterocycles has been enlarged by the discovery of the rearrangement of 10-substituted benzo[h]quinolines into compounds bearing an azonia-pyrene moiety. Acid-mediated intramolecular cyclization of derivatives bearing -CH2 CN and -CH2 CO2 Et groups led to compounds bearing a 5-substituted benzo[de]pyrido[3,2,1-ij]quinolinium core. Advanced photophysical studies including time-correlated single photon counting (TCSPC) and transient absorption spectroscopy of 5-aminobenzo[de]pyrido[3,2,1-ij]quinolin-4-ium salt and 5H-benzo[de]pyrido[3,2,1-ij]quinolin-5-one showed their promising optical properties such as high fluorescence quantum yields (37-59%), which was almost independent of the solvent, and high tenability of the absorption band position upon changing the solvent. The benzo[de]pyrido[3,2,1-ij]quinolinium salt selectively stains nucleic acids (in the nucleus and mitochondria) in eukaryotic cells.

Abstract  This work investigated effects of a prototype oil dispersant on solubilization, sorption and desorption of three model PAHs in sediment-seawater systems. Increasing dispersant dosage linearly enhanced solubility for all PAHs. Conversely, the dispersant enhanced the sediment uptake of the PAHs, and induced significant desorption hysteresis. Such contrasting effects (adsolubilization vs. solubilization) of dispersant were found dependent of the dispersant concentration and PAH hydrophobicity. The dual-mode models adequately simulated the sorption kinetics and isotherms, and quantified dispersant-enhanced PAH uptake. Sorption of naphthalene and 1-methylnaphthalene by sediment positively correlated with uptake of the dispersant, while sorption of pyrene dropped sharply when the dispersant exceeded its critical micelle concentration (CMC). The deepwater conditions diminished the dispersant effects on solubilization, but enhanced uptake of the PAHs, albeit sorption of the dispersant was lowered. The information may aid in understanding roles of dispersants on distribution, fate and transport of petroleum PAHs in marine systems.

Abstract  The hybridisation of metal oxides and nanocarbons has created a promising new class of functional materials for environmental and sustainable energy applications. The performance of such hybrids can be further improved by rationally designing interfaces and morphologies. Atomic layer deposition (ALD) is among the most powerful techniques for the controlled deposition of inorganic compounds, due to its ability to form conformal coatings on porous substrates at low temperatures with high surface sensitivity and atomic control of film thickness. The hydrophobic nature of the nanocarbon surface has so far limited the applicability of ALD on CNTs. Herein we investigate the role of structural defects in CNTs, both intrinsic and induced by acid treatment, on coverage, uniformity and crystallinity of ZnO coatings. Furthermore, we demonstrate the potential of small aromatic molecules, including benzyl alcohol (BA), naphthalene carboxylic acid (NA) and pyrene carboxylic acid (PCA), as active nucleation sites and linking agents. Importantly, only PCA exhibits sufficiently strong interactions with the pristine CNT surface to withstand desorption under reaction conditions. Thus, PCA enables a versatile and non-destructive alternative route for the deposition of highly uniform metal oxide coatings onto pristine CNTs via ALD over a wide temperature range and without the typical surface corrosion induced by covalent functionalisation. Importantly, preliminary tests demonstrated that the improved morphology obtained with PCA has indeed considerably increased the hybrid's photocatalytic activity towards hydrogen evolution via sacrificial water splitting. The concept demonstrated in this work is transferable to a wide range of other inorganic compounds including metal oxides, metal (oxy)nitrides and metal chalcogenides on a variety of nanocarbons.