Volatile Polycyclic Aromatic Hydrocarbons Research Articles

Assessment of the bioaccessibility of PAHs and other hazardous compounds present in recycled tire rubber employed in synthetic football fields.

Recycled tire crumb rubber (RTCR) surfaces contain harmful and carcinogenic substances, which can be ingested by the users of these facilities, mainly athletes and children. In this work, the potential in-vitro oral bioaccessibility of eighteen polycyclic aromatic hydrocarbons (PAHs) from RTCR employed as infill in synthetic football fields was studied in human synthetic body fluids (saliva, gastric, duodenal and bile), prepared according the Unified Bioaccessibility Method. Solid-phase extraction (SPE) using commercial sorbents and a new green material based on cork (cork industry by-product) were used to isolate the bioaccessible PAHs before gas chromatography-tandem mass spectrometry analysis. The method was optimized and validated attending the analytical figures of merit. The feasibility of cork biosorbent for the extraction of the compounds was demonstrated, as well as the suitability of the UBM method to perform the digestion with good precision. The application to real samples collected from football fields demonstrated the presence of 17 of the 18 target PAHs in the biofluids. Most volatile PAHs such as NAP, ACY, ACE, FLU, PHN and ANC, achieved the highest bioaccessibility percentage levels. The carcinogenic B[a]P was detected in 75 % of the samples at concentrations up to 2.5 ng g-1 (bioaccessible fraction). Children exposure assessment was carried out to identify potential risk. Other hazardous and environmentally problematic compounds such as N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPD-quinone), recently related with the dead of coho salmon, and hexamethoxymethylmelamine (HMMM), among others, were also detected. This is the first study in which the bioaccesibility from real crumb rubber samples of 15 out of the 16 PAHs considered as priority pollutants by the United States Environmental Protection Agency (EPA) and the presence of 6PPD-quinone and HMMM in the bioaccessible fractions is reported.

Naphthalene Detection in Air by Highly Sensitive TiO2 Sensor: Real Time Response to Concentration Changes Monitored by Simultaneous UV Spectrophotometry.

Volatile low-weight polycyclic aromatic hydrocarbons (PAHs) are known to be potentially toxic to humans and animals. Their detection in ambient air has been of great interest in recent years and various detection methods have been implemented. In this study, we used naphthalene as a basic model of such compounds and constructed our own version of a titanium oxide-based sensor system for its detection. The main goal of the study was to clearly demonstrate the effectiveness of this type of sensor, record its response under well-controlled conditions, and compare that response to concentration measurements made by the widely accepted spectrophotometric method. With that goal in mind, we recorded the sensor response while monitoring naphthalene vapor concentrations down to 95 nM as measured by spectrophotometry. Air flow over the sensor was passed continuously and sample measurements were made every 3 min for a period of up to 2 h. Over that period, several cycles of naphthalene contamination and cleaning were implemented and measurements were recorded. The relative humidity and temperature of the air being sampled were also monitored to assure no major variations occurred that could affect the measurements. The sensor showed high sensitivity and a reproducible response pattern to changes in naphthalene concentration. It could be easily “cleaned” of the compound in ten minutes by means of the application of UV light and the passing of fresh air. Pending testing with other volatile PAH, this type of sensor proves to be an effective and inexpensive way to detect naphthalene in air.

Deuterium Isotope Fractionation of Polycyclic Aromatic Hydrocarbons in Meteorites as an Indicator of Interstellar/Protosolar Processing History.

The stable isotope composition of soluble and insoluble organic compounds in carbonaceous chondrites can be used to determine the provenance of organic molecules in space. Deuterium enrichment in meteoritic organics could be a residual signal of synthetic reactions occurring in the cold interstellar medium or an indicator of hydrothermal parent-body reactions. δD values have been measured in grains and bulk samples for a wide range of meteorites; however, these reservoirs are highly variable and may have experienced fractionation during thermal and/or aqueous alteration. Among the plethora of organic compounds in meteorites are polycyclic aromatic hydrocarbons (PAHs), which are stable and abundant in carbonaceous chondrites, and their δD ratio may preserve evidence about their formation environment as well as the influence of parent-body processes. This study tests hypotheses about the potential links between PAHs-deuteration concentrations and their formation conditions by examining the δD ratio of PAHs in three CM carbonaceous chondrites representing an aqueous alteration gradient. We use deuterium enrichments in soluble 2–5-ring PAHs as an indicator of either photon-driven deuteration due to unimolecular photodissociation in warm regions of space, gas-phase ion–molecule reactions in cold interstellar regions of space, or UV photolysis in ices. We also test hypothesized reaction pathways during parent-body processing that differ between partially and fully aromatized PAHs. New methodological approaches were developed to extract small, volatile PAHs without fractionation. Our results suggest that meteoritic PAHs could have formed through reactions in cold regions, with possible overprinting of deuterium enrichment during aqueous parent-body alteration, but the data could not rule out PAH alteration in icy mantles as well.

Photocatalytic air purification of polycyclic aromatic hydrocarbons: Application of a flow-through reactor, kinetic studies and degradation pathways

This study investigates the performance of a newly developed flow-through reactor and the utilized photocatalytic materials in two environments: a lab-scale experiment and a pilot-scale experiment in a contaminated building. The aim was to assess the removal of polycyclic aromatic hydrocarbons from the air using an innovative reactor equipped with an ultraviolet-irradiated titanium dioxide catalyst. Empirical measurements were conducted in the laboratory to revise the developed fixated titanium dioxide catalysts at different irradiances. Naphthalene and 1-methylnaphthalene elimination were used as model substances due to being the most volatile polycyclic aromatic hydrocarbons (PAH). In addition, they are often found in contaminated buildings. Tests in an office building revealed high suitability of the air cleaning system for low polycyclic aromatic hydrocarbons concentrations with a degradation of the compounds below the allowed limits of indoor air pollutants set by the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety. The degradation of the organic micropollutants proceeded without detection of by-products, so that mineralization can be assumed. Based on these observations and a large number of previous studies, detailed degradation pathways for the selected micropollutants were also established.

Extraction and determination of organic/inorganic pollutants in the ambient air of two cities located in metropolis of Tehran.

In the present study, PM2.5, volatile organic compounds (VOC), heavy metals, and polycyclic aromatic hydrocarbons (PAHs)-bonded PM2.5 as well as asbestos fibers were investigated in two cities in the east of Tehran, Iran. To this end, 72 samples were collected from six stations located in the cities of Varamin and Pakdasht from March 2018 to March 2019. The concentration of BTEX compounds, PAHs, and heavy metals were measured using gas chromatography-flame ionization detector (GC-FID), gas chromatography-mass spectrometry (GC-Mas), and inductively coupled plasma atomic emission spectroscopy (ICP-OES), respectively. In addition, phase contrast microscopy (PCM) method was used to identify the properties of asbestos fibers. The results obtained from the present showed that the mean concentrations of PM2.5, heavy metals, PAHs, BTEX, and asbestos fibers were 52.05µg/m3, 319.08ng/m3, 3.97ng/m3, 40.58µg/m3, and 2.84 f/L, respectively. In addition, the results obtained from PCA and heavy metals sources showed that transport fleets were the natural source of most of these pollutants. In case of PAH sources, transport and incineration of coal had the highest contribution in the emission. Furthermore, the risk assessment showed that most of the compounds have a higher risk value than the guideline value spatial distribution and also showed that stations close to airports, city terminals, and highways were more polluted than other parts of the city. Therefore, in order to have healthy air and with the least pollution, it seems necessary to formulate the necessary strategies in the cities of Varamin and Pakdasht.

Volatilization behavior of polycyclic aromatic hydrocarbons from the oil-based residues of shale drill cuttings

Shale gas, an emerging oil-bearing and pillar industry at home and abroad, has a very large impact on economic development and industry, but the resulting emerging pollutants pose a serious threat to the environment. Drilling cuttings, the primary byproduct of the exploration and mining of shale gas, are potentially hazardous types of waste that seriously deplete land resources and pose environmental safety problems. In this paper, a long-term static volatilization experiment was conducted to study the volatilization of polycyclic aromatic hydrocarbons (PAHs) in the oil-based residue of shale gas drill cuttings. Furthermore, the effects of some relevant environmental factors controlling the volatilization behavior were evaluated, including different particle sizes, temperatures and illuminances. The results showed that (1) the volatilization concentrations of PAHs gradually increased with prolonged volatilization time. PAHs with smaller ring numbers were present at the highest concentrations among the detected PAHs, and they were more readily volatilized and could be detected earlier. (2) The C-history method was found to significantly describe the kinetic process of the volatilization of PAHs. (3) Different environmental factors had different effects on the volatilization of PAHs. We found that increasing the temperature and illuminance and decreasing the particle size increased volatility. Through canonical correspondence analysis, PAHs volatilization was found to be a complex process, so volatilization tests under simulated environmental conditions are of scientific and environmental interest.

Combustion products generated in simulated industrial fires

Studies of firefighter exposure to combustion products have focused predominantly on real or simulated residential structure fires, with few investigations considering industrial fire scenarios. This study measured the atmospheric concentrations of a variety of volatile organic compounds (VOCs), acid gases, and polycyclic aromatic hydrocarbons (PAHs) produced during fires in simulated industrial premises, as well as the deposition of PAHs onto the structural firefighting ensembles worn by the firefighters involved in extinguishment activities. Ingress of these combustion products into the structural firefighting ensembles during firefighting was also measured. Benzene concentrations of up to 23 mg/m3 and total PAH concentrations ranging from 1.7 to 8.6 mg/m3 were observed in personal air samples collected outside the structural firefighting ensembles, as well as a variety of acid gases including hydrogen chloride and hydrogen cyanide. Most combustion products detected outside the structural firefighting ensembles were also detected inside the ensembles, although often at much lower concentrations. The degree of protection observed was not uniform across all the combustion products investigated, with lower levels of protection found for gaseous combustion products such as benzene, xylene, hydrogen cyanide, and hydrochloric acid as compared with PAHs. Deposition of a variety of PAH compounds was observed on the outer surface of the structural firefighting ensembles, with total PAH concentrations ranging from 161 to 347 ng/cm2. While similar combustion products are involved in firefighter exposures during residential and industrial fires, deposition rates of PAHs, may be substantially higher during industrial firefighting. This research provides evidence supporting fireground decontamination measures for management of contamination of structural firefighting ensembles and equipment worn or carried by firefighters during firefighting activities. Further research is required to investigate the potential for dermal deposition of PAHs during actual industrial fire responses, and characterize which stages of fire and firefighting operations contribute the most to firefighters’ exposure to particular contaminants.

Maternal exposure to polycyclic aromatic hydrocarbons in South Texas, evaluation of silicone wristbands as personal passive samplers

BackgroundPrenatal exposure to polycyclic aromatic hydrocarbons (PAHs) is associated with adverse health effects in children. Valid exposure assessment methods with accurate spatial and temporal resolution across pregnancy is a critical need for advancing environmental health studies.ObjectiveThe objective of this study was to quantify maternal PAH exposure in pregnant women residing in McAllen, Texas where the prematurity rate and childhood asthma prevalence rates are high. A secondary objective was to compare PAH levels in silicone wristbands deployed as passive samplers with concentrations measured using standardized active air-sampling techniques.MethodsParticipants carried a backpack that contained air-sampling equipment (i.e., filter and XAD sorbent) and a silicone wristband (i.e., passive sampler) for three nonconsecutive 24-h periods. Filters, XAD tubes, and wristbands were analyzed for PAHs.ResultsThe median level of exposure for the sum of 16 PAHs measured via active sampling over 24 h was 5.54 ng/m3 (filters) and 43.82 ng/m3 (XADs). The median level measured in wristbands (WB) was 586.82 ng/band. Concentrations of the PAH compounds varied across sampling matrix type. Phenanthrene and fluorene were consistently measured for all participants and in all matrix types. Eight additional volatile PAHs were measured in XADs and WBs; the median level of exposure for the sum of these eight PAHs was 342.98 ng/m3 (XADs) and 632.27 ng/band. The silicone wristbands (WB) and XAD sorbents bound 1-methynaphthalyne, 2-methylnaphthalene, biphenyl following similar patterns of detection.SignificanceSince prior studies indicate linkages between PAH exposure and adverse health outcomes in children at the PAH levels detected in our study, further investigation on the associated health effects is needed. Data reflect the ability of silicone wristbands to bind smaller molecular weight, semivolatile PAHs similar to XAD resin. Application of wristbands as passive samplers may be useful in studies evaluating semivolatile PAHs.

Atmospheric deposition of semivolatile organic pollutants in European high mountains: Sources, settling and chemical degradation

Bulk atmospheric deposition samples, including wet and dry deposition, were collected during 2004–2006 in four high mountain European lakes: Skalnate Pleso (Tatra mountains, Slovakia), Gossenköllesee (Alps, Austria), Redon (Pyrenees, Spain), and Lochnagar (Grampian Mountains, Scotland). Samples were analysed for polycyclic aromatic hydrocarbons (PAHs), polychlorobiphenyls (PCBs), hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), endosulfans, and polybromodiphenyl ethers (PBDEs).The deposition of PCBs, HCHs, and low brominated BDEs reflected baseline contributions from long range atmospheric transport. This was also the case for PAHs in Redon and Gossenköllesee, endosulfans in Lochnagar and Gossenköllesee and HCB in these three lakes. However, Skalnate received PAHs, endosulfans, and HCB from regional sources as it was the case for endosulfans in Redon. The distinct origin of these pollutants was reflected in the relative composition of some metabolites such as the proportion of endosulfan sulfate vs α- and β-endosulfans or the relative composition of BDE47 and BDE99.Wet deposition was the main process for atmospheric removal of PAHs, HCHs, and HCB. In addition, warm season revolatilization from soils and melting snow with subsequent condensation at low temperature were significant for volatile PAHs, HCB, low chlorinated PCBs, and endosulfans.Reaction with OH radicals was not a significant loss process of HCHs and HCB in remote areas, dominated by wet deposition, whereas PCBs and PAHs were significantly removed by both wet deposition and OH radical oxidation, the latter dominating in the highest altitude sites. Photolysis was the main atmospheric removal process of PBDEs, dominating over atmospheric deposition and OH depletion in all sites.

Polycyclic aromatic hydrocarbon contamination along roads based on levels on vehicle window films.

Vehicular emissions are known to be major contributors of airborne polycyclic aromatic hydrocarbons (PAHs) in cities. In order to assess the long-term contamination of PAHs along roads, we collected organic films from vehicle windows (26 private cars and 4 buses, in Shanghai, China) and used mathematical models to convert the film-bound PAH concentrations to the airborne PAH concentrations. The field measurements of airborne PAHs revealed that the partitioning and Level III fugacity model was suitable to estimate the airborne concentrations of high and low volatile PAHs (expect for naphthalene), respectively. The total airborne PAH concentrations along roads in Shanghai ranged from 0.83 to 3.37μgm-3 and the incremental lifetime cancer risks (ILCRtotal) by exposure to PAHs along roads were greater than the USEPA lower guideline of 10-6, indicating non-negligible carcinogenic risks to drivers and passengers, especially via ingestion processes. This study provided a practicable method to investigate long-term air contamination of PAHs in vehicles and along roads based on film-bound PAH on vehicle windows. In addition, it was also possible to investigate the health risk in vehicles as a result of exposure to PAHs. Comparisons of PAHs between roads and shipping lanes also facilitated the delineation of vehicular and shipping PAH inventories. A capsule that summarizes the main finding of the work: Investigating film-bound PAH on vehicle windows is a practicable pathway to investigate the long-term contamination of PAHs in vehicles and along roads. This method can not only simplify the sampling processes, but the model calculations. The results also enabled investigations into ILCR in vehicles and specified source apportionment of traffic PAHs.

Net volatilization of PAHs from the North Pacific to the Arctic Ocean observed by passive sampling.

The North Pacific-Arctic Oceans are important compartments for semi-volatile organic compounds' (SVOCs) global marine inventory, but whether they act as a "source" or "sink" remains controversial. To study the air-sea exchange and fate of SVOCs during their poleward long-range transport, low-altitude atmosphere and surface seawater were measured for polycyclic aromatic hydrocarbons (PAHs) by passive sampling from July to September in 2014. Gaseous PAH concentrations (0.67-13ngm-3) were dominated by phenanthrene (Phe) and fluorene (Flu), which displayed an inverse correlation with latitude, as well as a significant linear relationship with partial pressure and inverse temperature. Concentrations of PAHs in seawater (1.8-16ngL-1) showed regional characteristics, with higher levels near the East Asia and lower values in the Bering Strait. The potential impact from the East Asian monsoon was suggested for gaseous PAHs, which - similar to PAHs in surface seawater - were derived from combustion sources. In addition, the data implied net volatilization of PAHs from seawater into the air along the entire cruise; fluxes displayed a similar pattern to regional and monthly distribution of PAHs in seawater. Our results further emphasized that air-sea exchange is an important process for PAHs in the open marine environments.

Volatilization of polycyclic aromatic hydrocarbons (PAHs) over the North Pacific and adjacent Arctic Ocean: The impact of offshore oil drilling.

Air and seawater samples were collected in 2016 over the North Pacific Ocean (NPO) and adjacent Arctic Ocean (AO), and Polycyclic Aromatic Hydrocarbons (PAHs) were quantified in them. Atmospheric concentrations of ∑15 PAHs (gas+particle phase) were 0.44-7.0ngm-3 (mean=2.3ngm-3), and concentrations of aqueous ∑15 PAHs (dissolved phase) were 0.82-3.7ngL-1 (mean=1.9ngL-1). Decreasing latitudinal trends were observed for atmospheric and aqueous PAHs. Results of diagnostic ratios suggested that gaseous and aqueous PAHs were most likely to be related to the pyrogenic and petrogenic sources, respectively. Three sources, volatilization, coal and fuel oil combustion, and biomass burning, were determined by the PMF model for gaseous PAHs, with percent contributions of 10%, 44%, and 46%, respectively. The 4- ring PAHs underwent net deposition during the cruise, while some 3- ring PAHs were strongly dominated by net volatilization, even in the high latitude Arctic region. Offshore oil/gas production activities might result in the sustained input of low molecular weight 3- ring PAHs to the survey region, and further lead to the volatilization of them. Compared to the gaseous exchange fluxes, fluxes of atmospheric dry deposition and gaseous degradation were negligible. According to the extrapolated results, the gaseous exchange of semivolatile aromatic-like compounds (SALCs) may have a significant influence on the carbon cycling in the low latitude oceans, but not for the high latitude oceans.

Cooling assisted headspace microextraction by packed sorbent coupled to HPLC for the determination of volatile polycyclic aromatic hydrocarbons in soil

A headspace microextraction by packed sorbent technique (HS-MEPS) was developed that is assisted by cooling the extraction phase and, in the same time, heating the sample matrix. The innovated cooling assisted HS-MEPS system was optimized for the extraction and HPLC determination of volatile polycyclic aromatic hydrocarbons (PAHs) in solid samples. Amino ethyl-functionalized SBA-15 was used as a nanoporous sorbent for packing the conical hub of the MEPS syringe. For efficient extraction of PAHs, several parameters such as the nature and mass of sorbent, eluent type, elution volume, extraction temperature and number of draw-eject cycles of the syringe were studied and optimized. Under the optimal experimental conditions, only 2 mg of the sorbent was sufficient by applying a temperature of 0 °C to the sorbent while the sample was heated up to 150 °C. Linear calibration curves (R2 > 0.95) were obtained for all the studied PAHs and their quantitation limits were in the range of 0.042–0.25 ng g−1. The method was successfully applied to the extraction and HPLC analysis of PAHs in some polluted soil samples.

Removal efficiency and mass balance of polycyclic aromatic hydrocarbons, phthalates, ethoxylated alkylphenols and alkylphenols in a mixed textile-domestic wastewater treatment plant

In this work the occurrence and fate of polycyclic aromatic hydrocarbons (PAHs), phthalic acid esters (PAEs), mono and diethoxylate alkylphenols (AP1–2EOs) and alkylphenols (APs) have been investigated during a two-weeks period in a facility treating mixed textile-domestic wastewater (Prato, Italy). The wastewater treatment plant (WWTP) consists of primary sedimentation, activated sludge biological oxidation, secondary sedimentation, clariflocculation and ozonation. The sludge is treated within the facility by thickening, dewatering and final incineration, thus providing the almost quantitative removal of the adsorbed micropollutants. Naphthalene (50%), di(2-ethylhexyl) phthalate (74%) and branched 4-nonylphenols (59%) were the individual main representative compounds of each class in the influent wastewater, which showed concentration ranges of 5.6–66, 85–290 and 21–133μg/L for PAHs, PAEs and APs+AP1–2EOs, respectively. The WWTP efficiently removed PAHs, PAEs and APs+AP1–2EOs, providing effluent concentrations of 0.075–0.16ng/L 0.38–9.9μg/L and 0.53–1.4μg/L. All targeted priority and priority-hazardous micropollutants showed effluent concentrations in line with the European environmental quality standards (EQS), even though for di(2-ethylhexyl) phthalate and benzo(a)pyrene after correction for the dilution factor of the recipient. The WWTP performance was evaluated by mass balance, verifying its accuracy by monitoring Pb and Cd as conservative species. The biological treatment sections provided mass losses of 85.5%, 74.5% and 56.8% for APs+AP1–2EOs, PAEs and PAHs, highlighting efficient biotransformation performances of the activated sludge process. However, for the more volatile PAHs (e.g. naphthalene), a significant contribution of stripping cannot be excluded. A remarkable mass loss was also determined in the ozonation stage for PAEs (72.9%) and especially PAHs (97.0%), whereas a lower efficiency was observed for APs+AP1–2EOs (41.3%). The whole plant allowed for obtaining an almost quantitative removal (96.7–98.4%) for all targeted compounds.

Toenail concentrations of trace elements and occupational history in pancreatic cancer

BackgroundSome occupations potentially entailing exposure to cadmium, arsenic, lead, selenium, nickel, and chromium have been associated with an increased risk of exocrine pancreatic cancer (EPC), but no studies have assessed whether body concentrations of such compounds differed among subjects occupationally exposed and unexposed. No studies which found that exposure to such metals increased the risk of EPC assessed whether past occupations were the source of exposure. ObjectiveThe aim was to analyse the relationship between toenail concentrations of trace elements and occupational history in EPC patients. MethodsThe study included 114 EPC cases personally interviewed on occupational history and lifestyle factors. Occupations were coded according to the International Standard Classification of Occupations 1988. Selected occupational exposures were assessed by two industrial hygienists and with the Finnish job-exposure matrix (Finjem). Concentrations of 12 trace elements were determined in toenail samples by inductively coupled plasma mass spectrometry. Adjusted geometric means (aGMs) and 95% confidence intervals (95% CI) were calculated. ResultsPatients occupationally exposed to aromatic hydrocarbon solvents (AHs) had higher concentrations of cadmium, manganese, lead, iron and vanadium. The aGM of cadmium concentrations for cases exposed to any pesticide was 0.056 μg/g [95% CI: 0.029–0.108], and, for unexposed cases, 0.023 μg/g [0.017–0.031]. Patients occupationally exposed to pesticides had higher concentrations of cadmium and manganese. Higher concentrations of vanadium, lead and arsenic were related to exposure to formaldehyde. Vanadium and lead were also associated with exposure to chlorinated hydrocarbon solvents, and arsenic was related to exposure to polycyclic aromatic hydrocarbons (PAHs). ConclusionsPatients occupationally exposed to AHs, pesticides, chlorinated hydrocarbon solvents, formaldehyde, volatile sulphur compounds and PAHs had higher concentrations of several metals. These elements may account for some of the occupational risks previously reported for pancreatic cancer.

The Photodynamic Properties and the Genotoxicity of Heat-Treated Silicalite-1 Films.

We investigated the use of a supported silicalite-1 film (SF) as a promising coating for metallic materials used in the fabrication of prostheses. The role of carbonaceous residua present on high-temperature calcined-SF in generating singlet oxygen for future use as a sterilization method has also been addressed, and the potential genotoxicity of these residua in osteoblast-like cells has been investigated. Calcination of as-synthesized SF induced the appearance of a rather complicated mixture of aliphatic and aromatic species on its outer surface. A series of variously volatile polycyclic aromatic hydrocarbons (PAH), including naphthalene, fluorene, phenanthrene, anthracene, fluoranthene, and pyrene, were identified in micromole concentrations. Irradiation of these PAHs on calcined-SF immersed in air-saturated chloroform led to the formation of very low concentrations of singlet oxygen. However, an increased level of DNA damage was observed on calcined-SF by immunofluorescence staining of phosphorylated histone H2AX analyzed by flow cytometry.

Environmental Forensic Investigation in the Residential Neighborhood Volta Grande IV, Volta Redonda, RJ, Brazil, Using TPH and PAHs Analyses in Soil Samples

This article presents the results of a forensic investigation concerning the origin of hydrocarbons detected in the subsurface soil of the residential neighborhood Volta Grande IV, Volta Redonda, RJ, Brazil. Previous investigations identified several areas with concentrations of volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs) above the Brazilian regulatory standards of CONAMA 420/2009 within the study area. Concern was raised that these hydrocarbons might be derived from local steel mill wastes. This forensic investigation determined that the VOCs in the residential soil are associated with gasoline and possibly diesel fuel oil releases into the subsurface soils that are not associated with the steel mill waste. The PAHs in residential subsurface soil generally fell below background concentrations and are likely associated with regional soot. The PAHs in the three samples with concentrations above background (out of a total of thirty-six samples) exhibit compositional features similar to coal byproducts, such as tar and coke, possibly attributable to the steel mill operation. This work discusses the geoforensic data and chemical signatures that support these findings.

Drivers of atmospheric deposition of polycyclic aromatic hydrocarbons at European high-altitude sites

Abstract. Polycyclic aromatic hydrocarbons (PAHs) were analysed in bulk atmospheric deposition samples collected at four European high-mountain areas, Gossenköllesee (Tyrolean Alps), Redon (Central Pyrenees), Skalnate Pleso (High Tatra Mountains), and Lochnagar (Grampian Mountains) between 2004 and 2006. Sample collection was performed monthly in the first three sites and biweekly in Lochnagar. The number of sites, period of study and sampling frequency provide the most comprehensive description of PAH fallout in high mountain areas addressed so far. The average PAH deposition fluxes in Gossenköllesee, Redon and Lochnagar ranged between 0.8 and 2.1 µg m−2 month−1, and in Skalnate Pleso it was 9.7 µg m−2 month−1, showing the influence of substantial inputs from regional emission sources. The deposited distributions of PAHs were dominated by parent phenanthrene, fluoranthene and pyrene, representing 32 %–60 % of the total. The proportion of phenanthrene, the most abundant compound, was higher at the sites of lower temperature, Gossenköllesee and Skalnate Pleso, showing higher transfer from gas phase to particles of the more volatile PAHs. The sites with lower insolation, e.g. those located at lower altitude, were those with a higher proportion of photooxidable compounds such as benz[a]anthracene. According to the data analysed, precipitation is the main driver of PAH fallout. However, when rain and snow deposition were low, particle settling also constituted an efficient driver for PAH deposition. Redon and Lochnagar were the two sites receiving the highest amounts of rain and snow and the fallout of PAH fluxes was related to this precipitation. No significant association was observed between long-range backward air trajectories and PAH deposition in Lochnagar, but in Redon PAH fallout at higher precipitation was essentially related to air masses originating from the North Atlantic, which were dominant between November and May (cold season). In these cases, particle-normalised PAH fallout was also associated with higher precipitation as these air masses were concurrent with lower temperatures, which enhanced gas to particle partitioning transfer. In the warm season (June–October), most of the air masses arriving at Redon originated from the south and particle deposition was enhanced as consequence of Saharan inputs. In these cases, particle settling was also a driver of PAH deposition despite the low overall PAH content of the Saharan particles. In Gossenköllesee, the site receiving lowest precipitation, PAH fallout was also related to particle deposition. The particle-normalised PAH fluxes were significantly negatively correlated to temperature, e.g. for air masses originating from central and eastern Europe, showing a dominant transfer from gas phase to particles at lower temperatures, which enhanced PAH fallout, mainly of the most volatile hydrocarbons. Comparison of PAH atmospheric deposition and lacustrine sedimentary fluxes showed much higher values in the latter case of 24–100 µg m−2 yr−1 vs. 120–3000 µg m−2 yr−1. A strong significant correlation was observed between these two fluxes, which is consistent with a dominant origin related to atmospheric deposition at each site.

Effects of fuel-bound methyl groups and fuel flow rate in the diffusion flames of aromatic fuels on the formation of volatile PAHs

Aromatic hydrocarbons constitute a significant fraction of fossil-derived transportation fuels. They are also used as additives to suppress autoignition and to increase fuel energy density. However, they produce harmful polycyclic aromatic hydrocarbons (PAHs) and soot during combustion. In this work, the effects of methyl group(s) and the flow rate of aromatic fuels (benzene, toluene, and m-xylene) on the concentration of volatile PAHs bound to soot formed in diffusion flames are studied. Soxhlet extraction using dichloromethane as the solvent is used to extract PAHs from soot particles collected from the flames of aromatic fuels. The extracts are analyzed using a gas chromatograph coupled to a mass spectrometer. Among the sixteen priority PAHs, fifteen of them are detected on soot particles along with benzo(e)pyrene and other organic compounds such as oxygenated compounds and mono-aromatic hydrocarbons. The PAHs containing two to three aromatic rings were found to be in higher concentrations than those with four or more rings. The total amount of PAHs collected at different fuel flow rates from the three aromatic fuels increased marginally in the following order: benzene < toluene < m-xylene. With increasing fuel flow rate, while the soot emission increased drastically, the concentration of volatile PAHs increased nearly linearly at a very slow rate. The toxicity of soot particles from different flames with increasing fuel flow rate is also reported.

Pivotal Role of Snow Deposition and Melting Driving Fluxes of Polycyclic Aromatic Hydrocarbons at Coastal Livingston Island (Antarctica).

The atmosphere-land-ocean dynamics of semivolatile organic compounds in polar regions is poorly understood,also for the abundant and ubiquitous polycyclic aromatic hydrocarbons (PAHs). We report the concentrations and fluxes of PAHs in a polar coastal ecosystem (Livingston Island, Antarctica). From late spring (December 2014) to late summer (February 2015), we sampled air, snow, coastal seawater, plankton, and the fugacity in soils and snow. The concentrations of PAHs in seawater were low but increased during the austral summer. The PAH concentrations in snow were significantly higher than in coastal seawater. Soil-air fugacity ratios showed a net volatilization of PAH when soils were covered with lichens, and close to air-soil equilibrium for bare soils. Concentrations in surface snow were also close to equilibrium with atmospheric PAHs. Conversely, there was a net diffusive deposition of PAHs to coastal seawater during late spring, but a net volatilization from seawater during late summer. Volatilization fluxes were correlated with seawater temperature and salinity, consistent with a key role of snowmelt to the fluxes and dissolved phase concentrations during the austral summer. The comprehensive assessment provided here shows that the fugacity amplification in snow is transferred to soils and coastal seawater supporting PAH concentrations and fluxes.