Solvent-extractable Organic Matter Research Articles

Toxicological effects of solvent-extracted organic matter associated with PM2.5 on human bronchial epithelial cell line NL-20

The heterogeneity and complexity of solvent-extracted organic matter associated with PM2.5 (SEOM-PM2.5) is well known; however, there is scarce information on its biological effects in human cells. This work aimed to evaluate the effect of SEOM-PM2.5 collected in northern Mexico City during the cold-dry season (November 2017) on NL-20 cells, a human bronchial epithelial cell line. The SEOM obtained accounted for 15.5% of the PM2.5 mass and contained 21 polycyclic aromatic hydrocarbons (PAHs). The cell viability decreased following exposure to SEOM-PM2.5, and there were noticeable morphological changes such as increased cell size and the presence of cytoplasmic vesicles in cells treated with 5–40 μg/mL SEOM-PM2.5. Exposure to 5 μg/mL SEOM-PM2.5 led to several alterations compared with the control cells, including the induction of double-stranded DNA breaks based (p < 0.001); nuclear fragmentation and an increased mitotic index (p < 0.05); 53BP1 staining, a marker of DNA repair by non-homologous end-joining (p < 0.001); increased BiP protein expression; and reduced ATF6, IRE1α, and PERK gene expression. Conversely, when exposed to 40 μg/mL SEOM-PM2.5, the cells showed an increase in reactive oxygen species formation (p < 0.001), BiP protein expression (p < 0.05), and PERK gene expression (p < 0.05), indicating endoplasmic reticulum stress. Our data suggest concentration-dependent toxicological effects of SEOM-PM2.5 on NL-20 cells, including genotoxicity, genomic instability, and endoplasmic reticulum stress.

Effects of solvent extracted organic matter from outdoor air pollution on human type II pneumocytes: Molecular and proteomic analysis

Outdoor air pollution is responsible for the exacerbation of respiratory diseases in humans. Particulate matter with an aerodynamic diameter ≤2.5 μm (PM2.5) is one of the main components of outdoor air pollution, and solvent extracted organic matter (SEOM) is adsorbed to the main PM2.5 core. Some of the biological effects of black carbon and polycyclic aromatic hydrocarbons, which are components of PM2.5, are known, but the response of respiratory cell lineages to SEOM exposure has not been described until now. The aim of this study was to obtain SEOM from PM2.5 and analyze the molecular and proteomic effects on human type II pneumocytes. PM2.5 was collected from Mexico City in the wildfire season and the SEOM was characterized to be exposed on human type II pneumocytes. The effects were compared with benzo [a] pyrene (B[a]P) and hydrogen peroxide (H2O2). The results showed that SEOM induced a decrease in surfactant and deregulation in the molecular protein and lipid pattern analyzed by reflection-Fourier transform infrared (ATR-FTIR) spectroscopy on human type II pneumocytes after 24 h. The molecular alterations induced by SEOM were not shared by those induced by B[a]P nor H2O2, which highlights specific SEOM effects. In addition, proteomic patterns by quantitative MS analysis revealed a downregulation of 171 proteins and upregulation of 134 proteins analyzed in the STRING database. The deregulation was associated with positive regulation of apoptotic clearance, removal of superoxide radicals, and positive regulation of heterotypic cell-cell adhesion processes, while ATP metabolism, nucleotide process, and cellular metabolism were also affected. Through this study, we conclude that SEOM extracted from PM2.5 exerts alterations in molecular patterns of protein and lipids, surfactant expression, and deregulation of metabolic pathways of type II pneumocytes after 24 h of exposure in absence of cytotoxicity, which warns about apparent SEOM silent effects.

Multi-analytical Approach (FTIR, XRF, XRD, GC-MS) Characterization of Source Rocks from the Anza Basin, Kenya

Potential source rocks from three wells (Chalbi-3, Sirius-1, and Ndovu-1) in the Anza Basin of northeastern Kenya were analyzed using elemental carbon-hydrogen-nitrogen analysis, and mineralogical characterization by X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM-EDX).)&lt;strong&gt;. &lt;/strong&gt;A Gas Chromatography-Mass Spectrometry (GC-MS) analysis of the saturated aliphatic biomarkers was carried out to illuminate the organic matter source. The analytical results revealed that the source rocks have moderate to high total organic carbon (%TOC) content, suggesting conditions in the Basin favor organic production and preservation. The Hydrogen Indices (HI: 0.19–0.60 atomic ratios) typify a predominance of mixed type II/III (oil/gas-prone) with more type III (gas-prone) and less II (oil-prone) kerogens. The FTIR, XRF, and XRD results reveal that the studied source rock samples comprised mainly of quartz, followed by silicate-clay minerals and calcite minerals. The solvent-extractable organic matter investigation revealed biomarker distributions of n-alkanes and isoprenoids (pristane/ phytane ratios), suggesting that source rocks were derived from algae and bacteria deposited weakly anoxic and low toxic environmental conditions, with minimal contribution from terrestrial organic matter sources. Consequently, all three wells have hydrocarbon generation potential, particularly Ndovu-1, which displays good organic matter content to produce oil and gas. The hydrocarbon potential is excellent and capable of making expulsions of oil and/or gas from the wells at sufficient depths.

Size-dependent in vitro inhalation bioaccessibility of PAHs and O/N PAHs - Implications to inhalation risk assessment

Size segregated samples (<0.49, 0.49–0.95, 0.95–1.5, 1.5–3.0, 3.0–7.2 and > 7.2 μm) of atmospheric particulate matter (APM) were collected at a traffic site in the urban agglomeration of Thessaloniki, northern Greece, during the cold and the warm period of 2020. The solvent-extractable organic matter was analyzed for selected organic contaminants including polycyclic aromatic hydrocarbons (PAHs), and their nitro- and oxy-derivarives (NPAHs and OPAHs, respectively). Mean concentrations of ∑16PAHs, ∑6NPAHs and ∑10OPAHs associated to total suspended particles (TSP) were 18 ng m−3, 0.2 ng m−3 and 0.9 ng m−3, respectively, in the cold period exhibiting significant decrease (6.4, 0.2 and 0.09 ng m−3, respectively) in the warm period. The major amount of all compounds was found to be associated with the alveolar particle size fraction <0.49 μm. The inhalation bioaccessibility of PAHs and O/N PAHs was measured in vitro using two simulated lung fluids (SLFs), the Gamble's solution (GS) and the artificial lysosomal fluid (ALF). With both SLFs, the derived bioaccessible fractions (BAFs) followed the order PAHs > OPAHs > NPAHs. Although no clear dependence of bioaccessibility on particle size was obtained, increased bioaccessibility of PAHs and PAH derivatives in coarse particles (>7.2 μm) was evident. Bioaccessibility was found to be strongly related to the logKOW and the water solubility of individual compounds hindering limited mobilization of the most hydrophobic and less water-soluble compounds from APM to SLFs. The lifetime cancer risk due to inhalation exposure to bioaccessible PAHs, NPAHs and OPAHs was estimated and compared to those calculated from the particulate concentrations of organic contaminants.

Oxidative potential of solvent-extractable organic matter of ambient total suspended particulate in Bangkok, Thailand.

Oxidative stress is a key mechanism by which ambient particulate matter induces adverse health effects. Most studies have focused on the oxidative potential (OP) of water-soluble constituents, while there has been limited work on the OP of solvent-extractable organic matter (EOM OP). In this study, the EOM OP of ambient total suspended particulate (TSP) from Bangkok, Thailand, was determined using the dithiothreitol (DTT) assay. Positive matrix factorization (PMF), combined with chemical analysis of molecular markers, was employed to apportion the contributions of various emission sources to EOM OP. The volume-normalized OP initially increased with organic carbon (OC) concentration and plateaued gradually, while the mass-normalized OP fitted well with OC concentration using a power function. Fossil fuel combustion (62%) and plastic waste burning (23%) were the major contributors to EOM OP, while biomass burning demonstrated only a limited contribution. EOM OP correlated well with each group of polycyclic aromatic hydrocarbons (PAHs), suggesting that secondary formation of quinones associated with fossil fuel combustion and plastic waste burning could be an important pathway of TSP toxicity. This study underscores the importance of considering different emission sources when evaluating potential health impacts and the implementation of air pollution regulations.

Polybrominated diphenyl ethers and organochloride pesticides in the organic matter of air suspended particles in Mexico valley: A diagnostic to evaluate public policies

The presence of organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs) was analysed in air particulate matter ≤ 2.5 μm (PM2.5) and ≤10 μm (PM10) collected in the Metropolitan Zone of Mexico Valley (MZMV), during 2013 and 2014, respectively. Spatial and seasonal distributions of PM and their organic content named solvent extracted organic matter (SEOM) were determined. PM mass concentration and SEOM/PM ratios were compared with previous studies in 2006 in Mexico City. PM2.5 concentration was like found in 2006, however, PM10 decreased ∼43%. The SEOM/PM10 ratio was kept constant, suggesting a decrease in SEOM as well as PM10 emitted from natural sources, probably as a result of changes in the land use due to urban growth. A decrease ∼50% SEOM/PM2.5 ratio was observed in the same period, linked to adequate strategies and public policies applied by the local and federal governments to control the organic matter emitted from anthropogenic sources.Seven out of sixteen OCPs and five out of six PBDEs were found. The most common POPs were endosulfan I, endosulfan II, endosulfan sulfate, BDE-47 and BDE-99, present on >90% of the sampling days. OCPs in PM2.5 and PBDEs in PM10 showed seasonal variability. Higher PBDEs concentration in both particle sizes were observed at east and southeast of the MZMV, where one of the biggest landfills and wastewater treatment plants are located. OCPs in PM10 were mainly emitted from agricultural areas located to the southwest, southeast and east of the MZMV. OCPs in PM2.5 showed a regional contribution from the north and introduced into the valley. OCP degradation products were dominant over native OCPs, indicating no fresh OCP use. POPs comparison with other cities was made. Agreements and commissions created by the Mexican government reduced OCPs emissions, however, more effort must be made to control PBDE emission sources.

Quantification and characterization of hydrocarbon-filled porosity in oil-rich shales using integrated thermal extraction, pyrolysis, and solvent extraction

For oil-rich shales, current solvent extraction– and thermal extraction–based methods inaccurately measure hydrocarbon-filled porosity (vHC). Moreover, the hydrocarbon composition is not characterized by either method. Here, we show how open-system programmed thermal extraction and pyrolysis, LECO total organic carbon, Archimedes bulk density, and helium pycnometry measurements are integrated to calculate oil and gas pore volumes, characterize their composition, and estimate mobility. Use of a modified multiramp, slow-heating thermal extract, and pyrolysis temperature program further subdivides the vHC. Saturate–aromatic–resin–asphaltene (SARA) separation and gas chromatography of solvent-extracted organic matter and thermally extracted oils are used to compositionally classify the vHC. The segregated bulk compositions of gas- and oil-filled porosity measured via this method are shown to overlap and are broken into the following categories: gas-filled porosity (∼C1–C14), light oil–filled porosity (∼C6–C36), and heavy oil–filled porosity (∼C32–C36+). Furthermore, slow-heating multiramp thermal extraction can subdivide the light oil–filled porosity into four components capturing the C11–C13, C12–C16, C14–C20, and C17–C36 ranges of the extractable organic matter. Analysis of solvent-extracted oils by SARA identifies abundant saturates and aromatics in the light oil–filled porosity and abundant resins and asphaltenes in the heavy oil–filled porosity. Low-maturity shales can be dominated by heavy (C32+) oils rich in asphaltene and resin fractions not observed in the produced fluid. The ratios of SARA components in the C15+ fraction of produced fluid and core extract can be used to better estimate the potentially mobile vHC.

A review of traditional and advanced technologies for the removal of particulate matter in subway systems.

The pollution status of particulate matter (PM) in a subway system and technological trends in their reduction were discussed in this study. The levels of PM2.5 and PM10 are generally found to be higher in the underground platforms and tunnels than those in the outdoor air. It has also been reported that the composition of fine dust in the subway consists of various substances including heavy metals (like Fe), carbonaceous matter, and solvent extractable organic matter (SEOM). It was confirmed that subway dust was created mainly by wearing on wheels, rails, and brakes. In addition, the concentration of PM in such environment was influenced not only by internal factors (eg, operating conditions of trains and ventilation systems, number of passengers, and the structure of subway stations) but also by outside factors (eg, ambient air concentration). Up to now, various techniques (ventilation fans, platform screen doors (PSDs), magnetic filters, small jet fans, artificial intelligent ventilation systems, hybrid filters, etc) have been studied to reduce PM in underground subway systems. In this study, we reviewed the air quality of major subway stations with the focus on PM and relevant technologies for its reduction.

Bioremediation of PAH-contamined soils: Consequences on formation and degradation of polar-polycyclic aromatic compounds and microbial community abundance

A bioslurry batch experiment was carried out over five months on three polycyclic aromatic compound (PAC) contaminated soils to study the PAC (PAH and polar-PAC) behavior during soil incubation and to evaluate the impact of PAC contamination on the abundance of microbial communities and functional PAH-degrading populations. Organic matter characteristics and reactivity, assessed through solvent extractable organic matter and PAC contents, and soil organic matter mineralization were monitored during 5 months. Total bacteria and fungi, and PAH-ring hydroxylating dioxygenase genes were quantified. Results showed that PAHs and polar-PACs were degraded with different degradation dynamics. Differences in degradation rates were observed among the three soils depending on PAH distribution and availability. Overall, low molecular weight compounds were preferentially degraded. Degradation selectivity between isomers and structurally similar compounds was observed which could be used to check the efficiency of bioremediation processes. Bacterial communities were dominant over fungi and were most likely responsible for PAC degradation. Abundance of PAH-degrading bacteria increased during incubations, but their proportion in the bacterial communities tended to decrease. The accumulation of some oxygenated-PACs during the bioslurry experiment underlines the necessity to monitor these compounds during application of remediation treatment on PAH contaminated soils.

Macromolecular composition of terrestrial and marine organic matter in sediments across the East Siberian Arctic Shelf

Abstract. Mobilisation of terrestrial organic carbon (terrOC) from permafrost environments in eastern Siberia has the potential to deliver significant amounts of carbon to the Arctic Ocean, via both fluvial and coastal erosion. Eroded terrOC can be degraded during offshore transport or deposited across the wide East Siberian Arctic Shelf (ESAS). Most studies of terrOC on the ESAS have concentrated on solvent-extractable organic matter, but this represents only a small proportion of the total terrOC load. In this study we have used pyrolysis–gas chromatography–mass spectrometry (py-GCMS) to study all major groups of macromolecular components of the terrOC; this is the first time that this technique has been applied to the ESAS. This has shown that there is a strong offshore trend from terrestrial phenols, aromatics and cyclopentenones to marine pyridines. There is good agreement between proportion phenols measured using py-GCMS and independent quantification of lignin phenol concentrations (r2 = 0.67, p &lt; 0.01, n = 24). Furfurals, thought to represent carbohydrates, show no offshore trend and are likely found in both marine and terrestrial organic matter. We have also collected new radiocarbon data for bulk OC (14COC) which, when coupled with previous measurements, allows us to produce the most comprehensive 14COC map of the ESAS to date. Combining the 14COC and py-GCMS data suggests that the aromatics group of compounds is likely sourced from old, aged terrOC, in contrast to the phenols group, which is likely sourced from modern woody material. We propose that an index of the relative proportions of phenols and pyridines can be used as a novel terrestrial vs. marine proxy measurement for macromolecular organic matter. Principal component analysis found that various terrestrial vs. marine proxies show different patterns across the ESAS, and it shows that multiple river–ocean transects of surface sediments transition from river-dominated to coastal-erosion-dominated to marine-dominated signatures.

Cytotoxicity and genotoxicity induced in vitro by solvent-extractable organic matter of size-segregated urban particulate matter

Three organic fractions of different polarity, including a non polar organic fraction (NPOF), a moderately polar organic fraction (MPOF), and a polar organic fraction (POF) were obtained from size-segregated (<0.49, 0.49–0.97, 0.97–3 and >3 μm) urban particulate matter (PM) samples, and tested for cytotoxicity and genotoxicity using a battery of in vitro assays. The cytotoxicity induced by the organic PM fractions was measured by the mitochondrial dehydrogenase (MTT) cell viability assay applied on MRC-5 human lung epithelial cells. DNA damages were evaluated through the comet assay, determination of the poly(ADP-Ribose) polymerase (PARP) activity, and the oxidative DNA adduct 8-hydroxy-deoxyguanosine (8-OHdG) formation, while pro-inflammatory effects were assessed by determination of the tumor necrosis factor-alpha (TNF-α) mediator release. In addition, the Sister Chromatid Exchange (SCE) inducibility of the solvent-extractable organic matter was measured on human peripheral lymphocyte. Variations of responses were assessed in relation to the polarity (hence the expected composition) of the organic PM fractions, particle size, locality, and season. Organic PM fractions were found to induce rather comparable Cytotoxicity and genotoxicity of PM appeared to be rather independent from the polarity of the extractable organic PM matter (EOM) with POF often being relatively more toxic than NPOF or MPOF. All assays indicated stronger mass-normalized bioactivity for fine than coarse particles peaking in the 0.97–3 and/or the 0.49–0.97 μm size ranges. Nevertheless, the air volume-normalized bioactivity in all assays was highest for the <0.49 μm size range highlighting the important human health risk posed by the inhalation of these quasi-ultrafine particles.

Organic geochemistry of a high-latitude Lower Cretaceous lacustrine sediment sample from the Koonwarra Fossil Beds, South Gippsland, Victoria, Australia

The Koonwarra Fossil Beds are widely recognized for their high-fidelity preservation of freshwater/terrestrial vertebrate and invertebrate fossils. A preliminary investigation suggests that organic biomarkers are also exceptionally well preserved and could contribute significantly to understanding the ecology of this ancient lake system. Solvent-extractable organic matter was collected from a single feldspathic siltstone/mudstone sample and analyzed using gas chromatography-mass spectrometry (GC-MS). The distribution of n-alkanes suggests a significant input of terrestrial plant material into the lake. The very low ratio of eukaryotic steranes to bacterial hopanes may reflect the decomposition of abundant plant material in the lake. Polycyclic aromatic hydrocarbons may record wildfire activity in the surrounding watershed.

Biodegradation of the organic matter in a coking plant soil and its main constituents

In contaminated soils, several natural processes (e.g. biodegradation, oxidation) can induce degradation of organic pollutants. To evaluate the effects of biodegradation on the organic matter and the main organic constituents (coal and coal tar) of a coking plant soil, we conducted a batch incubation experiment, whereby mineral nutrient solution and a microbial inoculum from the coking plant soil were added to the different samples. Microbial counts were monitored during the 9months of the biodegradation experiment and the mineralization rate was quantified by measuring the CO2 produced and the content, molecular weight (MW) distribution and molecular composition of the solvent extractable organic matter. The microbial enumeration and mineralization rate demonstrated no biodegradation with the coal tar but biodegradation was observed for the coal and coking plant soil samples. The coking plant soil exhibited the highest biodegradation rate, probably due to complex interactions between the different organic and mineral phases and the presence of various nutrient and carbon sources. Biodegradation of the kerogen with subsequent production of lower MW compounds (n-alkanes and isoprenoids) was observed for both coal and coking plant soil samples. The results indicate that the kerogen could be a potential source of carbon for the microorganisms and showed the central role of coal in the changes observed for the coking plant soil.

Speciation of Organic Matter and Heavy Metals in Urban Wastewaters from an Emerging Country

Analytical scanning and transmission electron microscopy, sequential chemical extraction, and pyrolysis–gas chromatography on solvent-extractable organic matter are used to provide both direct and indirect speciation of heavy metals and organic matter in sewage-suspended solids and in biofilms taken from an urban sewer in an emerging country. Compared to developed countries where the domestic activities represent the main source of heavy metal pollution in wastewater, the combined sewer system of an emerging country also integrates significant contributions originating from the private drinking water supply system (Zn, Cu, Cr, and Ni), industrial discharges (Cu, Mn), and road dust transported by street washing (Pb). The relative importance of those sources changes drastically over time as evidenced by the difference in metal levels recorded between weekday and weekend effluents. Nevertheless, sewer biofilms are found to provide a good averaging of contaminant loads and they can be used as environmental archives. The speciation study reveals the predominance of neoformed minerals such as sulfides and phosphates and highlights the strong biogeochemical dynamics that takes place within the sewer system. Electron microscope observations of heavy metal-bearing phases proved to be necessary to provide a consistent interpretation of chemical extraction results. The molecular characterization of the solvent-extractable organic matter from biofilms reveals the presence of classical fingerprints of domestic activity such as fecal sterols and detergents but also confirms a major contribution of petroleum by-products consistent with a traffic-related pollution.

Organic compounds of PM2.5 in Mexico Valley: Spatial and temporal patterns, behavior and sources

A longitudinal study on spatial and temporal behavior of particles less than 2.5μm (PM2.5), solvent extracted organic matter (SEOM), polycyclic aromatic hydrocarbons (PAH), n-alkanes and nitro-PAH was carried out for a full year in 2006, at five sites simultaneously around the Metropolitan Zone of Mexico Valley (MZMV). There is rather uniform distribution of PM2.5 and SEOM in the MZMV regarding gravimetric mass concentration, while some specific organic chemical components showed mass heterogeneity. The highest mass concentrations of target compounds occurred in the dry seasons with respect to the rainy season. Bonfires and fireworks are probably responsible for extreme values of PM2.5, SEOM and PAH (≥228gmol−1). Benzo[ghi]perylene was the most abundant PAH, with C24–C26 the most abundant n-alkanes and 2-nitrofluoranthene and 9-nitroanthracene the most abundant nitro-PAH. The northeast zone was the area with the greatest presence of sources of incomplete diesel combustion, while the central for gasoline combustion. In the southwest, the biogenic sources were more abundant over the anthropogenic sources. This was opposite to the other sites. Factor analysis allowed us to relate different compounds to emitting sources. Three main factors were associated with combustion, pyrolysis and biogenic primary sources while the other factors were associated with secondary organic aerosol formation and industry. Correlation analyses indicated that SEOM originates from different primary emission sources or is formed by different processes than the other variables, except in southwest. Associations among variables suggest that PM2.5 in the northwest and in the southeast originated mainly from primary emissions or consisted of primary organic compounds. PM2.5 in the northeast, central and southwest contains a greater proportion of secondary organic compounds, with the less oxidized organic aerosols in the northeast and the most aged organic aerosol in the southwest. This follows the trends in the prevailing wind directions in MZMV during 2006.

Low temperature oxidation of a coking plant soil organic matter and its major constituents: An experimental approach to simulate a long term evolution

In contaminated soils, several natural processes (biodegradation, oxidation, etc.) can induce degradation of organic pollutants. The aim of this work was to evaluate the impact of an abiotic low-temperature oxidation on a coking plant soil and its main organic constituents (coal, coke, coal tar and road asphalts) in order to understand its long term evolution. This natural process was experimentally reproduced by oxidizing the soil and isolated organic matrices at 100 °C during 180 days. The samples were analyzed by total organic carbon measurements and elemental analyses, and the solvent-extractable organic matter was quantified by GC–MS (gas chromatography–mass spectrometry). Oxidation experiments on coal, coal tar and coking plant soil samples lead to the decrease in polycyclic aromatic hydrocarbon (PAH) concentrations correlated to an incorporation of oxygen evidenced by the production of oxygenated PAHs. The increasing amount of polar macromolecules and the decrease in solvent-extractable organic matter suggest a molecular growth through ether/ester cross-linking. The chemical environment of organic compounds and the presence of a reactive mineral fraction are important parameters that improve the efficiency of oxidation. This work reveals that abiotic low temperature oxidation, can strongly contribute to pollutant removal especially by a stabilization process and should be considered in the long term evolution of a soil.

Selective Separation of Oxy-PAH from n-Alkanes and PAH in Complex Organic Mixtures Extracted from Airborne PM2.5

A fast and simple fractionation method was optimized to selectively separate oxy-PAH from polycyclic aromatic hydrocarbons (PAH) and n-alkanes contained in solvent extracted organic matter (SEOM) from atmospheric particles with an aerodynamic diameter ≤2.5 μm (PM2.5). Samples were collected in Mexico City. Multivariate parameters were adjusted on a standard mixture, and on SEOM spiked with pure standard mixture solutions: type and amount of phase; packing densities; type, proportion and amount of solvents, and elution flow rates were tested under several elution schemes. Cyanopropylsilyl-bonded phase material was the selected stationary phase. The separation method was applied to real samples of SEOM (2.6, 5.6 and 8.5 mg) spiked with n-alkanes, PAH and oxy-PAH. n-Alkanes overlapped with PAH due to an excess of n-alkanes in real samples overloading the capacity of the stationary phase. Oxy-PAH was separated totally from n-alkanes and PAH. Mean recoveries ± confidence intervals (95%) for n-alkanes ranged from 53 ± 17% (n-tetracontane) to 101 ± 11% (n-hexacosane); for PAH from 58 ± 5% (phenanthrene) to 85 ± 9% (benzo[k]fluoranthene); and for oxy-PAH from 68 ± 12% (9,10-dihydrobenzo[a]pyren-7(8H)one) to 108 ± 9% (1,2-benzopyrone). This method is an efficient fractionation procedure to be applied to oxy-PAH, PAH and n-alkanes in complex organic mixtures extracted from PM2.5.

Temporal variation of nitro-polycyclic aromatic hydrocarbons in PM 10 and PM 2.5 collected in Northern Mexico City

With the aim to determine the presence of individual nitro-PAH contained in particles in the atmosphere of Mexico City, a monitoring campaign for particulate matter (PM 10 and PM 2.5) was carried out in Northern Mexico City, from April 2006 to February 2007. The PM 10 annual median concentration was 65.2 μg m − 3 associated to 7.6 μg m − 3 of solvent-extractable organic matter (SEOM) corresponding to 11.4% of the PM 10 concentration and 38.6 μg m − 3 with 5.9 μg m − 3 SEOM corresponding to 15.2% for PM 2.5. PM concentration and SEOM varied with the season and the particle size. The quantification of nitro-polycyclic aromatic hydrocarbons (nitro-PAH) was developed through the standards addition method under two schemes: reference standard with and without matrix, the former giving the best results. The recovery percentages varied with the extraction method within the 52 to 97% range depending on each nitro-PAH. The determination of the latter was effected with and without sample purification, also termed fractioning, giving similar results. 8 nitro-PAH were quantified, and their sum ranged from 111 to 819 pg m − 3 for PM 10 and from 58 to 383 pg m − 3 for PM 2.5, depending on the season. The greatest concentration was for 9-Nitroanthracene in PM 10 and PM 2.5, detected during the cold–dry season, with a median (10th–90th percentiles) concentration in 235 pg m − 3 (66–449 pg m − 3 ) for PM 10 and 73 pg m − 3 (18–117 pg m − 3 ) for PM 2.5. The correlation among mass concentrations of the nitro-PAH and criteria pollutants was statistically significant for some nitro-PAH with PM 10, SEOM in PM 10, SEOM in PM 2.5, NO X, NO 2 and CO, suggesting either sources, primary or secondary origin. The measured concentrations of nitro-PAH were higher than those reported in other countries, but lower than those from Chinese cities. Knowledge of nitro-PAH atmospheric concentrations can aid during the surveillance of diseases (cardiovascular and cancer risk) associated with these exposures.

Solvent extracted organic matter and polycyclic aromatic hydrocarbons distributed in size-segregated airborne particles in a zone of México City: Seasonal behavior and human exposure

Airborne particulate mass was collected in a cascade impactor, and the mass concentration of solvent extracted organic matter (SEOM) and polycyclic aromatic hydrocarbons (PAH) were determined. A greater mass concentration of particles, SEOM and PAH were obtained in the dry season than in the rainy season for all impact stages; however, in the rainy season the proportion of SEOM/particles mass increased for all stages. There was an average decrease in particle mass concentration of 52.1 ± 6.7%, a 33.6 ± 12.3% decrease in SEOM and a 43.9 ± 16.9% decrease in heavy PAH (≥228 g mol −1) in the rainy season. Heavy PAH were distributed in fine particles, while light PAH were more abundant in coarse particles. Estimations of SEOM and PAH inhaled daily by a person were made. Considering the carcinogenic PAH median mass (10th–90th percentiles) in 20 m 3 of air, and the sum of all stages that could be inhaled daily by a person, estimates of 137 ng day −1 (74–246) in the dry season and 57 ng day −1 (21–101) in the rainy season were determined. The toxic equivalent factors were calculated to more accurately characterize the carcinogenic properties of PAH mixtures. This was based on the contribution of the carcinogenic potency of benzo[ a]pyrene. These estimations would need to be considered in establishing standards for Mexican air quality. Correlations were shown between other atmospheric pollutants and masses of particles, SEOM and PAH. Vehicles were suggested as an emission source for SEOM and PAH.

Composition of Solvent-Extractable Organic Matter in Atmospheric Particles and Soils Collected at Scott Base, Antartica.

Atmospheric particulate matter and soil samples were collected around Scott Base, Antarctica and analyzed for solvent extractable organic compounds. Homologous compounds such as nalkanes, n-alkanols and n-alkanoic acids were present in all samples and are indicative of contamination from anthropogenic activities and to a lesser extent from natural microbial input. Extractable PAH and oxy- PAH also confirm vehicular exhaust as a contributor to the organic particulate matter emitted into the atmosphere at Scott Base. Petroleum molecular markers such as pristane and phytane, as well as hopanes and steranes were also found in some soil and air samples. The concentrations of organic compounds were similar to those reported for rural locales in the northern hemisphere, suggesting that activities at Scott Base are contaminating the environment.