Photochemical and other sources of organic compounds in the Canadian high arctic aerosol pollution during winter-spring

Anthropogenic emission controls organic aerosols at Gosan background site in the outflow from northeast Asia

Anthropogenic activities release substantial amounts of organic components into the atmosphere. In this study, eight groups of organic compounds such as polycyclic aromatic hydrocarbons (PAHs), hopanes, steranes, n-alkanes, fatty acids, fatty alcohols, phthalate esters, and lignin and resin acids were identified in the ambient aerosol samples collected from a regional background site in the Korean Climate Observatory at Gosan (KCOG), South Korea. The total identified organics were most abundant in winter (220 ± 60.3 ng m-3), followed by spring, autumn, and summer, with the predominance of n-fatty acids. All classes of aliphatic lipid components showed a significant positive correlation with fossil fuel-derived organic carbon (OC-FF) and biomass burning-derived organic carbon (OC-BB), indicating that they were abundantly emitted from anthropogenic sources such as fossil fuel combustion and biomass burning. The composition profiles and diagnostic ratios of PAHs indicate that they were largely derived from coal and/or biomass combustion in the continent. In contrast, hopanes are predominantly emitted from gasoline or diesel engines, particularly in the summer, from commercial ships. The high concentration of phthalates in the summer suggested that plastic emissions from the open ocean substantially contributed to the Gosan aerosols. The low ratios of unsaturated/saturated fatty acids indicate that Gosan organic aerosols were photochemically aged during atmospheric transport. The temporal and seasonal variations of organic species over KCOG provide crucial information on the emission strengths of different contributing sources in the East Asian outflow. Positive Matrix Factorization (PMF) results and 14C-based source apportionment studies demonstrated that anthropogenically derived organic aerosols largely contributed to the aerosol mass over KCOG. Thus, the East Asian continent might be the major source region for organic aerosols over the western North Pacific, except in the summer.

Seasonal characteristics of biogenic secondary organic aerosol tracers in a deciduous broadleaf forest in northern Japan

We collected total suspended particulate (TSP) samples from January 2010 to December 2010 at Sapporo deciduous forest to understand the oxidation processes of biogenic volatile organic compounds (BVOCs). The gas chromatography-mass spectrometric technique was applied to determine biogenic secondary organic aerosols (BSOAs) in the TSP samples. We found the predominance of the isoprene SOA (iSOA) tracers (20.6 ng m^-3) followed by α/β-pinene SOA (pSOA) tracers (8.25 ng m^-3) and β-caryophyllene SOA (cSOA) tracer (1.53 ng m^-3) in the forest aerosols. The results showed large isoprene fluxes and relatively high levels of oxidants in the forest atmosphere. The iSOA and pSOA tracers showed a clear seasonal trend with summer and autumn maxima and winter and spring minima. Their seasonal trends were mainly controlled by BVOCs emission from the local broadleaf deciduous forest. Additionally, the regional level of isoprene emissions from the oceanic sources may also be contributed during summertime aerosols. cSOA tracer showed high concentrations in the winter and spring, possibly due to an additional contribution of biomass burning (BB) aerosols from the local or regional BB activities. The biogenic secondary organic carbon (BSOC) was contributed mainly by the oxidation products of isoprene (136 ngC m^-3) followed by β-caryophyllene (63.0 ngC m^-3) and α/β-pinene (35.9 ngC m^-3). The mass concentration ratio (0.92) of pinonic acid + pinic acid and 3-methyl-1,2,3-butanetricarboxylic acid ((PNA + PA)/3-MBTCA) indicates the photochemical transformation of first-generation oxidation products to the higher generation oxidation products. The average ratios of isoprene to α/β-pinene (1.64) and β-caryophyllene (18.6) oxidation products suggested a large difference in the emissions of isoprene and α/β-pinene compared to β-caryophyllene. The cSOA tracers in the forest aerosols are also contributed by BB during the winter and spring. Positive matrix factorization analyses of the BSOA tracers confirmed that organic aerosols of deciduous forests are mostly related to isoprene emissions. This study suggests that isoprene is a more significant precursor for the BSOA than α/β-pinene and β-caryophyllene in a broadleaf deciduous forest.

Tracing the biomass burning emissions over the Arabian Sea in winter season: Implications from the molecular distributions and relative abundances of sugar compounds

The widespread haze pollution over South Asia typically occurs in winter, affecting the abundance of organic aerosols (OA) over the Arabian Sea due to prevailing meteorology. We determined the concentrations of biomass burning (BB) derived anhydrosugars (levoglucosan: Lev, galactosan: Gal, and mannosan: Man), sugars (glucose, fructose, sucrose, and trehalose) and sugar alcohols (arabitol, mannitol, erythritol, and inositol) over the Arabian Sea during a winter cruise (6-24 December 2018). Molecular distributions revealed predominance of levoglucosan or sucrose. Besides, levoglucosan strongly correlated with mannosan, galactosan, sugar alcohols and elemental carbon, emphasizing their BB-origin. Backward air mass trajectories intercepted by the satellite-based fire counts over the Indo-Gangetic Plain together with relationship between stable carbon isotopic composition of TC (δ¹³C_TC) and levoglucosan-C to organic carbon (%), confirmed the impact of BB-derived OA. A comparison of Lev/Man (av. 16.2) and Lev/K⁺ (av. 0.27) ratios over the Arabian Sea with the source-emissions revealed their origin from crop-residue burning. Rather high concentrations of Lev over the Arabian Sea compared to those documented over the Bay of Bengal, East China Sea, Sea of Japan and the western North Pacific further suggests a stronger impact of BB in the continental outflow over this marine basin. Besides, Lev/K⁺ ratios in marine aerosols exponentially decreased with an apparent increase in ambient relative humidity and temperature over the Arabian Sea during the South Asian outflow, implying a photochemical oxidation of BBOA. Such field-based relationship of Lev with the meteorological parameters can be useful for modelling the impact of BBOA on the surface Ocean. Besides, the aeolian input of sugar-C and water-soluble organic carbon (WSOC) accounted for 83 % and 92 % of that riverine supply to the Arabian Sea, respectively. This means atmospheric dry-deposition of sugars is an important external source of dissolved organic compounds to the surface water.

Investigating the Permeation Mechanism of Typical Phthalic Acid Esters (PAEs) and Membrane Response Using Molecular Dynamics Simulations

Phthalic acid esters (PAEs) are typical environmental endocrine disrupters, interfering with the endocrine system of organisms at very low concentrations. The plasma membrane is the first barrier for organic pollutants to enter the organism, so membrane permeability is a key factor affecting their biological toxicity. In this study, based on computational approaches, we investigated the permeation and intramembrane aggregation of typical PAEs (dimethyl phthalate, DMP; dibutyl phthalate, DBP; di-2-ethyl hexyl phthalate, DEHP), as well as their effects on membrane properties, and related molecular mechanisms were uncovered. Our results suggested that PAEs could enter the membrane spontaneously, preferring the headgroup-acyl chain interface of the bilayer, and the longer the side chain (DEHP > DBP > DMP), the deeper the insertion. Compared with the shortest DMP, DEHP apparently increased membrane thickness, order, and rigidity, which might be due to its stronger hydrophobicity. Potential of means force (PMF) analysis revealed the presence of an energy barrier located at the water-membrane interface, with a maximum value of 2.14 kcal mol−1 obtained in the DEHP-system. Therefore, the difficulty of membrane insertion is also positively correlated with the side-chain length or hydrophobicity of PAE molecules. These findings will inspire our understanding of structure-activity relationship between PAEs and their effects on membrane properties, and provide a scientific basis for the formulation of environmental pollution standards and the prevention and control of small molecule pollutants.

Water-soluble matter in PM2.5 in a coastal city over China: Chemical components, optical properties, and source analysis

Although marine and terrestrial emissions simultaneously affect the formation of atmospheric fine particles in coastal areas, knowledge on the optical properties and sources of water-soluble matter in these areas is still scarce. In this work, taking Qingdao, China as a typical coastal location, the chemical composition of PM_2.5 during winter 2019 was analyzed. Excitation-emission matrix fluorescence spectroscopy was combined with parallel factor analysis model to explain the components of water-soluble atmospheric chromophores of PM_2.5. Our analysis indicated that NO₃^-, NH₄⁺ and SO₄^2- ions accounted for 86.80% of the total ion mass, dominated by NO₃^-. The ratio of [NO₃^-]/[SO₄^2-] was up to 2.42 ± 0.84, suggesting that mobile sources play an important role in local pollutants emission. The result of positive correlation between Abs₃₆₅ with K⁺ suggests that biomass burning is an important source of water-soluble organic compounds (WSOC). Six types of fluorophores (C1-C6), all humic-like substances, were identified in WSOC. Humification index, biological index and fluorescence index in winter were 1.66 ± 0.34, 0.51 ± 0.44 and 1.09 ± 0.78, respectively, indicating that WSOC in Qingdao were mainly terrestrial organic matters. Overall, although the study area is close to the ocean, the contribution of terrestrial sources to PM_2.5, especially vehicle exhaust and coal combustion, is still much higher than that of marine sources. Our study provides a more comprehensive understanding of chemical and optical properties of WSOC based on PM_2.5 in coastal areas, and may provide ground for improving local air quality.

Dynamic variations of phthalate esters in PM2.5 during a pollution episode

Phthalate esters (PAEs) as hazardous air pollutants can be easily released during the life cycle of plastic products. In this study, a thermal desorption aerosol comprehensive two-dimensional gas chromatography mass spectrometer coupled with a dual-trap was developed and used to measure the hourly-resolved PAEs characteristics in atmospheric PM_2.5 at an urban site. Dimethyl phthalate (DMP), diethyl (DEP), dibutyl (DnBP), benzyl butyl (BBP), di(2-ethylhexyl) (DEHP), and di-n-octyl phthalate (DnOP) in PM_2.5 were analyzed. The most abundant compounds were DEHP and DMP, followed by DnBP and DEP. The mass concentrations of the detected PAEs are comparable to those at other urban sites measured using offline methods with a lower time resolution. The concentrations of PAEs showed intense change with the variation of PM_2.5 mass concentration. The proportion of DEHP increased while that of DMP decreased with the increase in PM_2.5 pollution. Positive correlations between PAEs and PM_2.5, organic carbon, and elemental carbon were observed, while PAEs had negative correlation with the ambient temperature. Our observation provides evidences on understanding the volatile and semi-volatile PAEs in the ambient aerosols.

Terrestrial lipid biomarkers in marine aerosols over the western North Pacific during 1990-1993 and 2006-2009

Terrestrial lipid biomarkers are one of the key tracers in the studies of atmospheric aerosols. Here, we investigated such organic compounds in marine aerosols collected at Chichijima Island, the western North Pacific for two 4-year periods: 1990-1993 and 2006-2009. A homologous series of lipid biomarkers including C₁₈-C₃₇n-alkanes, C₉-C₃₄ fatty acids, and C₁₄-C₃₅ fatty alcohols were determined by gas chromatography/mass spectrometry (GC/MS). The atmospheric levels of these tracers increased from 1990-1993 to 2006-2009. Their seasonal trends were clearly characterized by winter-spring maxima and summer-fall minima. The relative abundance of the high-molecular-weight (HMW) n-alkanes (C₂₅-C₃₇) and n-alcohols (C₂₀-C₃₅) in total HMW lipids peaked in winter and winter/fall, respectively, whereas those of HMW fatty acids (C₂₀-C₃₄) peaked in summer. Air-mass backward trajectory analyses suggest that the Asian continent, Southeast Asia including tropical regions, and the Central Pacific are the main source regions. The seasonal shift and distribution of the carbon preference index and average chain length for the HMW lipids were controlled by the changes in climatic factors and source regions. The higher abundance of terrestrial lipids during 2006-2009 than 1990-1993 indicates a higher emission from terrestrial plantation in the 2000s than in the early 1990s in upwind regions of East Asia. Furthermore, HMW lipid compounds exhibited much stronger positive correlations with levoglucosan, a biomass-burning tracer, during 2006-2009 than 1990-1993, suggesting that biomass-burning emissions contributed more significantly in this century.

Water-Soluble Anions in PM10 Samples Collected in the Metropolitan Area of Costa Rica: Temporal and Spatial Variations

The concentrations of water-soluble anions present in PM10 collected from ambient air in four sites of Costa Rica’s greater metropolitan area (GAM) were analyzed. Samples were collected over a 24-h period for three days during the 2011–2018 period, using high-volume air samplers with mass flow controller. The PM10 samples were collected using quartz fiber filters, which were analyzed using ion chromatography to identify organic and inorganic ions. The annual averages for PM10, F−, Cl−, and SO42− showed significant differences between the sampling sites, with Uruca (UR) consistently registering annual averages above the maximum concentration established by Costa Rica’s air quality regulations (30 µgm−3). The ions analyzed contributed 33%, 34%, 35%, and 37% of the PM10 mass for sampling sites UR, HA, AL, and CA, respectively. Using Spearman correlations and principal component analysis (PCA), the following contributions were identified: biomass burning, secondary particle formation processes from mobile and stationary emissions, and biogenic emissions. For each variable, seasonal patterns and trends were analyzed using time series with additive decomposition.

Polycyclic aromatic compounds in the Canadian Environment: Aquatic and terrestrial environments

Polycyclic aromatic compounds (PACs) are ubiquitous across environmental media in Canada, including surface water, soil, sediment and snowpack. Information is presented according to pan-Canadian sources, and key geographical areas including the Great Lakes, the Alberta Oil Sands Region (AOSR) and the Canadian Arctic. Significant PAC releases result from exploitation of fossil fuels containing naturally-derived PACs, with anthropogenic sources related to production, upgrading and transport which also release alkylated PACs. Continued expansion of the oil and gas industry indicates contamination by PACs may increase. Monitoring networks should be expanded, and include petrogenic PACs in their analytical schema, particularly near fuel transportation routes. National-scale roll-ups of emission budgets may not expose important details for localized areas, and on local scales emissions can be substantial without significantly contributing to total Canadian emissions. Burning organic matter produces mainly parent or pyrogenic PACs, with forest fires and coal combustion to produce iron and steel being major sources of pyrogenic PACs in Canada. Another major source is the use of carbon electrodes at aluminum smelters in British Columbia and Quebec. Temporal trends in PAC levels across the Great Lakes basin have remained relatively consistent over the past four decades. Management actions to reduce PAC loadings have been countered by increased urbanization, vehicular emissions and areas of impervious surfaces. Major cities within the Great Lakes watershed act as diffuse sources of PACs, and result in coronas of contamination emanating from urban centres, highlighting the need for non-point source controls to reduce loadings.

Trace Level Determination of Saccharides in Pristine Marine Aerosols by Gas Chromatography-Tandem Mass Spectrometry

The quantification and identification of saccharides in pristine marine aerosols can provide useful information for determining the contributions of anthropogenic and natural sources of the aerosol. However, individual saccharide compounds in pristine marine aerosols that exist in trace amounts are difficult to analyze due to their low concentrations. Thus, in this study, we applied gas chromatography-tandem mass spectrometry (GC-MS/MS) in multiple reaction monitoring (MRM) mode to analyze the particulate matter with an aerodynamic diameter equal or less than 2.5 μm (PM2.5) samples, and the results were compared with those of conventional GC-MS. To investigate the chemical properties of pristine marine aerosols, 12 PM2.5 samples were collected while aboard Araon, an ice-breaking research vessel (IBRV), as it sailed from Incheon, South Korea to Antarctica. The method detection limits of GC-MS/MS for 10 saccharides were 2-22-fold lower than those of GC-MS. Consequently, the advantages of GC-MS/MS include (1) more distinct peak separations, enabling the accurate identification of the target saccharides and (2) the quantification of all individual saccharide compounds with concentrations outside the quantifiable range of GC-MS. Accordingly, the time resolution for sampling saccharides in pristine marine aerosols can be improved with GC-MS/MS.

Seasonal variation of dicarboxylic acids in PM2.5 in Beijing: Implications for the formation and aging processes of secondary organic aerosols

Dicarboxylic acids are a group of highly oxidized components, which can provide insights into the formation mechanism and aging process of secondary organic aerosols (SOA). Based on the 12-h day and night PM_2.5 samples collected in downtown Beijing in January, April, July and October of 2017, dicarboxylic acids and relevant components were measured to investigate their seasonal variation pattern and sources. High concentrations of the identified organic acids were observed, following the decreasing order of July > January > October > April. The high fractions of phthalic acid and maleic acid in January indicated severe aromatic SOA pollution during the sampling period in winter, and the high malonic acid to succinic acid and malic acid to succinic acid ratios in July suggested strong photochemical formation over the sampling period in summer. Based on the calculation of principle component analysis and multiple linear regression, water-soluble organic acids were mainly formed from the aerosol aging process during the sampling periods except for January, while water-soluble organic carbon (WSOC) mostly originated from combustion sources. Correlation analysis was conducted between the CO-normalized concentrations of organic acids and PM_2.5, O₃, as well as the meteorological parameters. The results suggested that gas-phase photooxidation contributed significantly to the formation of these organic acids during the entire sampling period, and the aqueous-phase process played an important role over the severe haze event in January. Our results also suggested that the intensity of photooxidation and the aging degree of SOA were enhanced along with the reduction of PM_2.5 in Beijing in recent years.

Biogenic secondary organic aerosol formation in an urban area of eastern central India: Seasonal variation, size distribution and source characterization

Samples of ambient aerosols were collected at an urban site of eastern central India from monsoon to summer 2016-17 for the characterization of biogenic secondary organic aerosols (BSOA). The BSOA tracers derived from isoprene, α/β-pinene and β-caryophyllene in size-distributed aerosols were studied. Concentrations of total SOAI (Isoprene secondary organic aerosols) were found more abundant than α/β-pinene in summer, while contradictory trends were found in the winter season, where SOAM (monoterpene derived SOA) and SOAS (sesquiterpenes derived SOA) were dominated. Size-distribution study revealed that most of the BSOA were formed in the aerosol phase and dominated in fine mode, except cis-pinonic acid. They were formed in the gaseous phase and partitioned onto the aerosol phase. The alkaline nature of mineral dust particles that triggered the adsorption of gaseous species onto pre-existing particles could be the reason for bimodal size distribution with major coarse mode peak and miner fine mode peak. Temporal variations suggest that the BSOA must be derived from terrestrial vegetation and biomass burning. The isoprene SOC (secondary organic carbon) contributed 0.91%, 1.38%, 0.88% and 1.04% to OC during winter, summer, post-monsoon and monsoon season, respectively. The isoprene SOC in fine mode was found to be higher than the coarse mode.

Year-round measurements of size-segregated low molecular weight organic acids in Arctic aerosol

Organic acids in aerosols Earth's atmosphere are ubiquitous and they have been extensively studied across urban, rural and polar environments. However, little is known about their properties, transport, source and seasonal variations in the Svalbard Archipelago. Here, we present the annual trend of organic acids in the aerosol collected at Ny-Ålesund and consider their size-distributions to infer their possible sources and relative contributions. A series of carboxylic acids were detected with a predominance of C2-oxalic acid. Pinic acid and cis-pinonic acid were studied in order to better understand the oxidative and gas-to-particle processes occurred in the Arctic atmosphere. Since the water-soluble organic fraction is mainly composed by organic acids and ions, we investigated how the seasonal variation leads to different atmospheric transport mechanisms, focusing on the chemical variations between the polar night and boreal summer. Using major ions, levoglucosan and MSA, the Positive Matrix Factorization (PMF) identified five different possible sources: a) sea spray; b) marine primary production; c) biomass burning; d) sea ice related process and e) secondary products.

Molecular characteristics of organic compositions in fresh and aged biomass burning aerosols

Biomass burning (BB) is the most important source of primary organic aerosols (OA) in the atmosphere that has significant impact on local/regional air quality and human health. However, few studies paid attention to the evolution of molecular characteristics of BB OA in the atmospheric aging processes. In this study, both fresh and aged PM_2.5 aerosols from burning of rice, maize, and wheat straws were collected from a combined system of combustion chamber and oxidation flow reactor, and were analyzed for >100 organic species. The emission factors (EFs) of anhydrosugars and some fatty acids showed slight variations between fresh and aged samples, indicating that these compounds are relatively stable. However, the EFs of n-alkanes, fatty alcohols, and parent-PAHs decreased 8-57% from fresh to aged samples, suggesting that they can undergo further oxidation to form other organic materials in the atmosphere. Phthalic acids, nitrophenols and isoprene-derived products were mainly secondarily formed by aging processes. Thus their EFs increased by 2-23 times from fresh to aged samples. Levoglucosan was the most abundant individual organic tracer, and its EF varied slightly between fresh and aged samples, proving its indicative role on BB emission. Moreover, the ratio of vanillic acid to levoglucosan and p-hydroxybenzoic acid to levoglucosan increased 2-13 times from fresh to aged samples. Therefore they can be used to investigate the impact of aging processes on BB aerosols in the atmosphere. RO₂ + HO₂ pathway derived 2-methyltetrols (2-MTs) predominated the EFs of isoprene-derived products (SOA_i) in the fresh samples. However, RO₂ + NO pathway derived 2-methylglyceric acid (2-MGA) increased by >30 times and became comparable with 2-MTs in aged particles. The ratio of 2-MGA/2-MTs increased from 0.06-0.27 in fresh samples to 0.94-1.18 in aged samples, because the high loading of NO_x in BB smoke enhanced the formation of SOA_i through RO₂ + NO reactions.

Interannual variability of sugars in Arctic aerosol: Biomass burning and biogenic inputs

The concentrations and particle-size distribution of sugars in Arctic aerosol samples were studied to investigate their potential sources and transport. Sugars are constituents of the water-soluble organic compounds (WSOC) fraction in aerosol particles where some saccharides are used as tracers of Primary Biological Aerosol Particles (PBAPs). Monosaccharides (arabinose, fructose, galactose, glucose, mannose, ribose, xylose), disaccharides (sucrose, lactose, maltose, lactulose), alcohol-sugars (erythritol, mannitol, ribitol, sorbitol, xylitol, maltitol, galactitol) and anhydrosugars (levoglucosan, mannosan and galactosan) were quantified in aerosol samples collected during three different sampling campaigns (spring and summer 2013, spring 2014 and 2015). The mean total concentrations of sugars were 0.4 ± 0.3, 0.6 ± 0.5 and 0.5 ± 0.6 ng m^-3 for 2013, 2014 and 2015 spring campaigns, while the mean concentration increased to 3 ± 3 ng m^-3 in the summer of 2013. This work identified a reproducibility in the sugars trend during spring, while the summer data in 2013 allowed to us to demonstrate strong local inputs when the ground was free of snow and ice. Furthermore, the study aims to show that the two specific ratios of sorbitol & galactiol to arabinose were diagnostic for the type of biomass that was burnt. This study demonstrates that not only is long-range atmospheric transport significant. But depending on seasonality, local inputs can also play an important role in the chemical composition of sugars in Arctic aerosol.

Wintertime Arctic Sea Spray Aerosol Composition Controlled by Sea Ice Lead Microbiology

The Arctic is experiencing the greatest warming on Earth, as most evident by rapid sea ice loss. Delayed sea ice freeze-up in the Alaskan Arctic is decreasing wintertime sea ice extent and changing marine biological activity. However, the impacts of newly open water on wintertime sea spray aerosol (SSA) production and atmospheric composition are unknown. Herein, we identify SSA, produced locally from open sea ice fractures (leads), as the dominant aerosol source in the coastal Alaskan Arctic during winter, highlighting the year-round nature of Arctic SSA emissions. Nearly all of the individual SSA featured thick organic coatings, consisting of marine saccharides, amino acids, fatty acids, and divalent cations, consistent with exopolymeric secretions produced as cryoprotectants by sea ice algae and bacteria. In contrast, local summertime SSA lacked these organic carbon coatings, or featured thin coatings, with only open water nearby. The individual SSA composition was not consistent with frost flowers or surface snow above sea ice, suggesting that neither hypothesized frost flower aerosolization nor blowing snow sublimation resulted in the observed SSA. These results further demonstrate the need for inclusion of lead-based SSA production in modeling of Arctic atmospheric composition. The identified connections between changing sea ice, microbiology, and SSA point to the significance of sea ice lead biogeochemistry in altering Arctic atmospheric composition, clouds, and climate feedbacks during winter.

Aromatic acids as biomass-burning tracers in atmospheric aerosols and ice cores: A review

Biomass burning (BB) is one of the largest sources of carbonaceous aerosols with adverse impacts on air quality, visibility, health and climate. BB emits a few specific aromatic acids (p-hydroxybenzoic, vanillic, syringic and dehydroabietic acids) which have been widely used as key indicators for source identification of BB-derived carbonaceous aerosols in various environmental matrices. In addition, measurement of p-hydroxybenzoic and vanillic acids in snow and ice cores have revealed the historical records of the fire emissions. Despite their uniqueness and importance as tracers, our current understanding of analytical methods, concentrations, diagnostic ratios and degradation processes are rather limited and scattered in literature. In this review paper, firstly we have summarized the most established methods and protocols for the measurement of these aromatic acids in aerosols and ice cores. Secondly, we have highlighted the geographical variability in the abundances of these acids, their diagnostic ratios and degradation processes in the environments. The review of the existing data indicates that the concentrations of aromatic acids in aerosols vary greatly with locations worldwide, typically more abundant in urban atmosphere where biomass fuels are commonly used for residential heating and/or cooking purposes. In contrast, their concentrations are lowest in the polar regions which are avoid of localized emissions and largely influenced by long-range transport. The diagnostic ratios among aromatic acids can be used as good indicators for the relative amounts and types of biomass (e.g. hardwood, softwood and herbaceous plants) as well as photochemical oxidation processes. Although studies suggest that the degradation processes of the aromatic acids may be controlled by light, pH and hygroscopicity, a more careful investigation, including closed chamber studies, is highly appreciated.

Sterols and stanols as novel tracers of waterbird population dynamics in freshwater ponds

With the expansion of urban centres in the mid-twentieth century and the post-1970 decrease in pesticides, populations of double-crested cormorants (Phalacrocorax auritus) and ring-billed gulls (Larus delawarensis) around Lake Ontario (Canada and USA) have rapidly rebounded, possibly to unprecedented numbers. Along with the use of traditional palaeolimnological methods (e.g. stable isotopes, biological proxies), we now have the capacity to develop specific markers for directly tracking the presence of waterbirds on nesting islands. Here, we apply the use of lipophilic sterols and stanols from both plant and animal-faecal origins as a reliable technique, independent of traditional isotopic methods, for pinpointing waterbird arrival and population growth over decadal timescales. Sterol and stanol concentrations measured in the guano samples of waterbird species were highly variable within a species and between the three species of waterbirds examined. However, cholesterol was the dominant sterol in guano, and phytosterols were also high in ring-billed gull guano. This variability highlights a specialist piscivorous diet for cormorants compared to a generalist, omnivorous diet for gulls, which may now often include grain and invertebrates from agricultural fields. A ratio that includes cholesterol and sitosterol plus their aerobically reduced products (cholestanol, stigmastanol) best explained the present range of bird abundance across the islands and was significantly correlated to sedimentary δ¹⁵N. Overall, we demonstrate the use of sterols and stanols as a direct means for tracking the spatial and temporal presence of waterbirds on islands across Lake Ontario, and probably elsewhere.

East Siberian Arctic background and black carbon polluted aerosols at HMO Tiksi

Assessment of Arctic pollution is hampered by a lack of aerosol studies in Northern Siberia. Black carbon observations were carried out at the Hydrometeorological Observatory Tiksi, a coast of Laptev sea, from September 2014 to September 2016. Aerosol sampling was accompanied by physico-chemical characterization. BC climatology showed a seasonal variation with highest concentrations from January to March (up to 450ng/m³) and lowest ones for June and September (about 20ng/m³). Stagnant weather and stable atmosphere stratification resulted in accumulation of pollution, in dependence on the wind direction and air mass transportation. Carbon fractions, functionalities, ions, and elements are associated to marine, biogenic, and continental sources. In September low OC, aliphatic, carbonyls, amines, and hydroxyls characterize background aerosols. Na⁺/Cl^- ratio much higher than in sea-salt indicates a strong Cl depletion. Increased OC, aromatic, carbonyls, and nitrocompounds as well as waste burning markers K⁺, Cl^-, and PO₄^2- confirm impacts from Tiksi landfill burns. BC pollution episodes are differentiated through increased EBC and sulfates, related to gas flaring, industrial and residential emissions transported from Western Siberia while the increase of carbonyls, hydroxyl, and aromatic indicate emissions sources from Yakutia and Tiksi urban area. Arctic Haze aerosols are characterized by increased concentrations of SO₄^2- in comparison with OC, much higher abundance of oxygenated compounds with respect to alkanes of anthropogenic origin. In summer rich organic chemistry indicates impacts of biogenic, local urban, and shipping sources as well as secondary aerosol formation influenced by emissions from low latitude Siberia.

Free phenolic compounds in waters of the Ross Sea

The presence of free phenolic compounds (PC) in Antarctic sea water has been investigated to explain their source and particle size distribution in the atmospheric aerosols, as determined in our previous research. The sea water samples were filtered to distinguish the PC concentrations in the particulate and dissolved fractions. Two sample preparation procedures were developed to quantify nine PC in both fractions. The highest concentrations were found in the dissolved fraction of Ross Sea water, with vanillin, vanillic acid, acetovanillone and p-coumaric acid being the most abundant PC. Dissolved PC were mainly found in the upper part of water column. This facilitated the sea water-air exchange by bubble busting processes. In the aerosol, they were mainly found in the fine fraction, where these compounds have a higher degree of oxidation than PC detected in seawater, suggesting that they were newly emitted and they have been not yet oxidized. These results supported our previous hypothesis that PC were locally emitted into the atmosphere from the Ross Sea. Three different possible sources of PC are hypothesized for Antarctic sea waters: 1) from the intrusion of Modified Circumpolar Deep Water that may transport oceanic lignin; 2) from phytoplankton biomass that may be a source of PC in Antarctic waters since diatoms produce exudates that contain vanillic acid, p-coumaric acid and syringic acid; 3) from the melting of glaciers and sea ice: glaciers contain lignin that can be degraded, while in the sea ice there are diatoms that may release PC. Statistical analysis and the low value of vanillic acid/vanillin ratio indicated that the most plausible source for PC in the dissolved fraction was the senescence of phytoplankton. As a contrast, particulate PC with higher vanillic acid/vanillin ratios were ascribed to degraded lignin or the sorption of diagenically oxidized material on particles.

Distribution of phthalates in Marseille Bay (NW Mediterranean Sea)

Phthalic Acid Esters (PAEs) are a group of emerging organic contaminants that have become a serious issue because of their ubiquitous presence and hazardous impact on the marine environment worldwide. Seawater samples were collected monthly from December 2013 to November 2014 in the northwestern Mediterranean Sea (Marseille Bay). The samples were analyzed for dissolved organic carbon (DOC) as well as the molecular distribution of dissolved PAEs by using solid phase extraction followed by gas chromatography and mass spectrometry (GC/MS) analyses. The results demonstrated the occurrence of six PAEs, including dimethyl phthalate (DMP), diethyl phthalate (DEP), di-isobutyl phthalate (DiBP), di-n-butyl phthalate (DnBP), benzylbutyl phthalate (BzBP) and diethylhexyl phthalate (DEHP), with total concentrations ranging from 130 to 1330ngL^-1 (av. 522ngL^-1). In Marseille Bay, the highest concentrations were detected in the bottom water from June to November 2014 and in the whole water column during the winter mixing period. This result suggests that resuspension of PAE-rich sediment, in relation to the accumulation of plastic debris above the seabed, or the higher degradation rate in the upper layer of the water column, plays a significant role in the PAE dynamics in coastal water. DEHP was the most abundant PAE in all of the surface samples and the summer bottom samples, followed by DiBP and DnBP, which also represent the largest fractions in the other bottom samples.

Current State, Distribution, and Sources of Phthalate Esters and Organophosphate Esters in Soils of the Three Gorges Reservoir Region, China

Phthalate esters (PAEs) and organophosphate esters (OPEs) were identified and quantified in surface soils from farmland and riparian areas of the Three Gorges Reservoir (TGR), western China. Generally, the mean values of PAEs and OPEs were 618 and 266 ng/g dry weight (dw) in farmland soil and 560 and 499 ng/g dw in riparian soil, respectively. The occurrence of OPEs should be regarded as a risk factor in the TGR region. Analogous spatial distribution patterns for PAEs were observed with higher concentrations observed at site WZ in both types of soil, which might relate to the anthropogenic activities. The hydrodynamic conditions might be important factors contributing to the slightly different spatial distribution of OPEs. The concentrations of OPEs in riparian soil exceed those in farmland soil at all sampling sites, which could partly be ascribed to the complete operation of the TGR. Dibutyl phthalate (DnBP) was the most dominated PAEs congener in both types of soil. Of particular note is the elevated contribution of tris(methylphenyl) phosphate (TMPP), followed by 2-ethylhexyl diphenyl phosphate (EHDPP), accounting for more than 90% of the total OPEs, and the shipping or/and the local human activity might be considered as the major contributor. The slight differences in PAEs composition of principal components might largely attribute to the variety of emission sources in two types of soil. The different cluster patterns between two types of soil indicated that the anthropogenic activities as well as the full operation of TGR, may play a role.

Photochemical transformation of dimethyl phthalate (DMP) with N(iii)(H2ONO+/HONO/NO2−) in the atmospheric aqueous environment

The primary step of photochemical transformation of dimethyl phthalate (DMP) with N(iii) is ˙OH-addition on the aromatic ring of DMP to form a DMP–OH adduct, followed by several decay channels and corresponding rate constants are determined.

Influence of continental organic aerosols to the marine atmosphere over the East China Sea: Insights from lipids, PAHs and phthalates

Total suspended particle (TSP) samples were collected during a marine cruise in the East China Sea from May 18 to June 12, 2014. They were analyzed for solvent extractable organic compounds (lipid compounds, PAHs and phthalates) using gas chromatography/mass spectrometry (GC/MS) to better understand the sources and source apportionment of aerosol pollution in the western North Pacific. Higher concentrations were observed in the terrestrially influenced aerosol samples on the basis of five-day backward air mass trajectories, especially for aerosols collected near coastal areas. Phthalates were found to be the dominant species among these measured compound classes (707±401ngm^-3 for daytime and 313±155ngm^-3 for nighttime), followed by fatty acids, fatty alcohols, n-alkanes and PAHs. In general, the daytime abundances for these compounds are higher than nighttime, possibly attributable to more intensive anthropogenic activities during the daytime. The factor analysis indicates that biomass burning, fungal activities and fossil fuel combustion maybe the main emission sources for organic aerosols over the East China Sea. This study demonstrates that the East Asian continent can be a natural emitter of biogenic and anthropogenic organics to the marine atmosphere through long-range transport, which controls the chemical composition and concentration of organic aerosols over the East China Sea.

Distributions of Polycyclic Aromatic Hydrocarbons, Aromatic Ketones, Carboxylic Acids, and Trace Metals in Arctic Aerosols: Long-Range Atmospheric Transport, Photochemical Degradation/Production at Polar Sunrise

The distributions, correlations, and source apportionment of aromatic acids, aromatic ketones, polycyclic aromatic hydrocarbons (PAHs), and trace metals were studied in Canadian high Arctic aerosols. Nineteen PAHs including minor sulfur-containing heterocyclic PAH (dibenzothiophene) and major 6 carcinogenic PAHs were detected with a high proportion of fluoranthene followed by benzo[k]fluoranthene, pyrene, and chrysene. However, in the sunlit period of spring, their concentrations significantly declined likely due to photochemical decomposition. During the polar sunrise from mid-March to mid-April, benzo[a]pyrene to benzo[e]pyrene ratios significantly dropped, and the ratios diminished further from late April to May onward. These results suggest that PAHs transported over the Arctic are subjected to strong photochemical degradation at polar sunrise. Although aromatic ketones decreased in spring, concentrations of some aromatic acids such as benzoic and phthalic acids increased during the course of polar sunrise, suggesting that aromatic hydrocarbons are oxidized to result in aromatic acids. However, PAHs do not act as the major source for low molecular weight (LMW) diacids such as oxalic acid that are largely formed at polar sunrise in the arctic atmosphere because PAHs are 1 to 2 orders of magnitude less abundant than LMW diacids. Correlations of trace metals with organics, their sources, and the possible role of trace transition metals are explained.

Seasonal variations and source profile of n-alkanes in particulate matter (PM10) at a heavy traffic site, Delhi

Delhi is one of the most polluted cities in the world. The generation of aerosols in the lower atmosphere of the city is mainly due to a large amount of natural dust advection and sizable anthropogenic activities. The compositions of organic compounds in aerosols are highly variable in this region and need to be investigated thoroughly. Twenty-four-hour sampling to assess concentrations of n-alkanes (ng/m³) in PM₁₀ was carried out during January 2015 to June 2015 at Indira Gandhi Delhi Technical University for Women (IGDTUW) Campus, Delhi, India. The total average concentration of n-alkanes, 243.7 ± 5.5 ng/m³, along with the diagnostic tools has been calculated. The values of CPI₁, CPI₂, and CPI₃ for the whole range of n-alkanes series, petrogenic n-alkanes, and biogenic n-alkanes were 1.00, 1.02, and 1.04, respectively, and C _max were at C₂₅ and C₂₇. Diagnostic indices and curves indicated that the dominant inputs of n-alkanes are from petrogenic emissions, with lower contribution from biogenic emissions. Significant seasonal variations were observed in average concentrations of n-alkanes, which is comparatively higher in winter (187.4 ± 4.3 ng/m³) than during the summer season (56.3 ± 1.1 ng/m³).

Size distributions of n-alkanes, fatty acids and fatty alcohols in springtime aerosols from New Delhi, India

Size-segregated aerosol samples were collected in New Delhi, India from March 6 to April 6, 2012. Homologous series of n-alkanes (C₁₉C₃₃), n-fatty acids (C₁₂C₃₀) and n-alcohols (C₁₆C₃₂) were measured using gas chromatography/mass spectrometry. Results showed a high-variation in the concentrations and size distributions of these chemicals during non-haze, haze, and dust storm days. In general, n-alkanes, n-fatty acids and n-alcohols presented a bimodal distribution, peaking at 0.7-1.1 μm and 4.7-5.8 μm for fine modes and coarse modes, respectively. Overall, the particulate matter mainly existed in the coarse mode (≥2.1 μm), accounting for 64.8-68.5% of total aerosol mass. During the haze period, large-scale biomass burning emitted substantial fine hydrophilic smoke particles into the atmosphere, which leads to relatively larger GMDs (geometric mean diameter) of n-alkanes in the fine mode than those during the dust storms and non-haze periods. Additionally, the springtime dust storms transported a large quantity of coarse particles from surrounding or local areas into the atmosphere, enhancing organic aerosol concentration and inducing a remarkable size shift towards the coarse mode, which are consistent with the larger GMDs of most organic compounds especially in total and coarse modes. Our results suggest that fossil fuel combustion (e.g., vehicular and industrial exhaust), biomass burning, residential cooking, and microbial activities could be the major sources of lipid compounds in the urban atmosphere in New Delhi.

Environmental Chemicals Modulate Polar Bear (Ursus maritimus) Peroxisome Proliferator-Activated Receptor Gamma (PPARG) and Adipogenesis in Vitro

We studied interactions between polar bear peroxisome proliferator-activated receptor gamma (pbPPARG) and selected compounds using a luciferase reporter assay and predictions through molecular docking. Furthermore, we studied adipogenesis by liver and adipose tissue extracts from a polar bear and three synthetic mixtures of contaminants in murine 3T3-L1 preadipocytes and polar bear adipose tissue-derived stem cells (pbASCs). PCB153 and p,p'-DDE antagonized pbPPARG, although their predicted receptor-ligand affinity was weak. PBDEs, tetrabromobisphenol A, and PCB170 had a weak agonistic effect on pbPPARG, while hexabromocyclododecane, bisphenol A, oxychlordane, and endosulfan were weak antagonists. pbPPARG-mediated luciferase activity was suppressed by synthetic contaminant mixtures reflecting levels measured in polar bear adipose tissue, as were transcript levels of PPARG and the PPARG target gene fatty acid binding protein 4 (FABP4) in pbASCs. Contaminant extracts from polar bear tissues enhanced triglyceride accumulation in murine 3T3-L1 cells and pbASCs, whereas triglyceride accumulation was not affected by the synthetic mixtures. Chemical characterization of extracts using nontarget methods revealed presence of exogenous compounds that have previously been reported to induce adipogenesis. These compounds included phthalates, tonalide, and nonylphenol. In conclusion, major legacy contaminants in polar bear adipose tissue exert antagonistic effects on PPARG, but adipogenesis by a mixture containing emerging compounds may be enhanced through PPARG or other pathways.

Sterols and Stanols Preserved in Pond Sediments Track Seabird Biovectors in a High Arctic Environment

Seabirds are major vertebrates in the coastal ecosystems of the Canadian High Arctic, where they transport substantial amounts of marine-derived nutrients and pollutants from oceans to land by depositing guano and stomach oils to their nesting area, which often includes nearby freshwater ponds. Here we present novel indicators for evaluating the impact of seabirds on freshwater ecosystems. The ratio of cholesterol/(cholesterol + sitosterol) in pond sediments showed significant enrichment near a nesting colony of northern fulmars (Fulmarus glacialis) and was significantly correlated with ornithogenic enrichment of sediment as determined by sedimentary δ(15)N. The sterol ratio was also correlated with several bioaccumulative persistent organic pollutants (POPs), suggesting its usefulness in tracking biovector enrichment of contaminants. Human-derived epicoprostanol was also analyzed in the sediments, and its relationship with an abandoned, prehistoric camp was recorded, suggesting its potential as a tracer of prehistoric human activities in the Arctic. Sterols and stanols preserved in sediments appear to be useful geochemical tools that will inform our understanding of migratory species and the presence of prehistoric human populations in the Arctic, and possibly other animal populations.

Particulate PAHs and n-alkanes in the air over Southern and Eastern Mediterranean Sea

Particulate polycyclic aromatic hydrocarbons, n-alkanes and polar organic compounds were investigated in the marine atmosphere of Southern and Eastern Mediterranean Sea, in the frame of the scientific cruise of Urania ship between 27 July and 11 August 2013. The PM10 fraction of aerosol to which most organic substances are associated, were collected daily; contemporarily, gaseous regulated toxicants (ozone, nitrogen oxides and carbon oxide) and carbonyls were recorded. Samplings were carried out in front of Palermo and Messina, respectively the start and end harbors, and along the cruise, both in movement (transects, N = 14) and at stops (N = 11). Total PAHs ranged from 0.06 ng/m(3) up to 1.8 ng/m(3), with the maximums observed close to harbors. Unlike total concentrations that were in general comparable, the percent composition of PAHs was distinct for harbors, transects and stops, which allowed to draw insights about the pollution sources impact. Concentrations of n-alkanes (C18-C35) ranging from 6.7 to 43 ng/m(3) were quantified. The carbonyls evaluation revealed relatively high concentrations of formaldehyde (∼4-24 μg/m(3)) and acetone (∼5-35 μg/m(3)) near harbors, and of acrolein (up to 12 μg/m(3)) offshore, while benzaldehyde was quite independent of the site type (≈0.5 μg/m(3)). Nicotine and caffeine were detected, at different extents (0.0-2.2 ng/m(3) and 0.01-0.17 ng/m(3), respectively), in ca. 70% and 100% of samples. Alkyl phthalates ranged from 2.7 to 67 ng/m(3) and showed variable percentages in the samples. Finally, traces of N,N-diethyl-meta-toluene amide (up to 0.4 ng/m(3)) were found at all sites.

Levoglucosan evidence for biomass burning records over Tibetan glaciers

Intense biomass burning (BB) events are widespread in tropical and subtropical Asia. However, the impact of BB aerosols on the Tibetan Plateau (TP), especially on Tibetan glaciers, is poorly understood. In this study, BB signals are revealed using the specific molecular tracer levoglucosan in snow and ice samples from different Tibetan glaciers. Tibetan glaciers mainly act as receptors of BB emissions from surrounding regions. Significant differences in levoglucosan concentrations in glacier samples collected from two slopes on the same mountain range indicate that high mountains can act as natural barriers to block the transport of smoke aerosols to the TP. Levoglucosan concentrations show a decreasing trend from west to east on glaciers impacted by the Indian summer monsoon on the southern edge of the TP, while the opposite pattern was observed on glaciers under the prevailing westerlies along the northern edge. The emission sources, the controlling climate system, as well as deposition and degradation during transport determined the spatial distribution regimes of levoglucosan concentration on Tibetan glaciers.

Levoglucosan and phenols in Antarctic marine, coastal and plateau aerosols

Due to its isolated location, Antarctica is a natural laboratory for studying atmospheric aerosols and pollution in remote areas. Here, we determined levoglucosan and phenolic compounds (PCs) at diverse Antarctic sites: on the plateau, a coastal station and during an oceanographic cruise. Levoglucosan and PCs reached the Antarctic plateau where they were observed in accumulation mode aerosols (with median levoglucosan concentrations of 6.4 pg m(-3) and 4.1 pg m(-3), and median PC concentrations of 15.0 pg m(-3) and 7.3 pg m(-3)). Aged aerosols arrived at the coastal site through katabatic circulation with the majority of the levoglucosan mass distributed on larger particulates (24.8 pg m(-3)), while PCs were present in fine particles (34.0 pg m(-3)). The low levoglucosan/PC ratios in Antarctic aerosols suggest that biomass burning aerosols only had regional, rather than local, sources. General acid/aldehyde ratios were lower at the coastal site than on the plateau. Levoglucosan and PCs determined during the oceanographic cruise were 37.6 pg m(-3) and 58.5 pg m(-3) respectively. Unlike levoglucosan, which can only be produced by biomass burning, PCs have both biomass burning and other sources. Our comparisons of these two types of compounds across a range of Antarctic marine, coastal, and plateau sites demonstrate that local marine sources dominate Antarctic PC concentrations.

Source Contributions to Wintertime Elemental and Organic Carbon in the Western Arctic Based on Radiocarbon and Tracer Apportionment

To quantify the contributions of fossil and biomass sources to the wintertime Arctic aerosol burden source apportionment is reported for elemental (EC) and organic carbon (OC) fractions of six PM10 samples collected during a wintertime (2012-2013) campaign in Barrow, AK. Radiocarbon apportionment of EC indicates that fossil sources contribute an average of 68 ± 9% (0.01-0.07 μg m(-3)) in midwinter decreasing to 49 ± 6% (0.02 μg m(-3)) in late winter. The mean contribution of fossil sources to OC for the campaign was stable at 38 ± 8% (0.04-0.32 μg m(-3)). Samples were also analyzed for organic tracers, including levoglucosan, for use in a chemical mass balance (CMB) source apportionment model. The CMB model was able to apportion 24-53% and 99% of the OC and EC burdens, respectively, during the campaign, with fossil OC contributions ranging from 25 to 74% (0.02-0.09 μg m(-3)) and fossil EC contributions ranging from 73 to 94% (0.03-0.07 μg m(-3)). Back trajectories identified two major wintertime source regions to Barrow: the Russian and North American Arctic. Atmospheric lifetimes of levoglucosan, ranging from 50 to 320 h, revealed variability in wintertime atmospheric processing of this biomass burning tracer. This study allows for unambiguous apportionment of EC to fossil fuel and biomass combustion sources and intercomparison with CMB modeling.

Carbonaceous aerosol tracers in ice-cores record multi-decadal climate oscillations

Carbonaceous aerosols influence the climate via direct and indirect effects on radiative balance. However, the factors controlling the emissions, transport and role of carbonaceous aerosols in the climate system are highly uncertain. Here we investigate organic tracers in ice cores from Greenland and Kamchatka and find that, throughout the period covered by the records (1550 to 2000 CE), the concentrations and composition of biomass burning-, soil bacterial- and plant wax- tracers correspond to Arctic and regional temperatures as well as the warm season Arctic Oscillation (AO) over multi-decadal time-scales. Specifically, order of magnitude decreases (increases) in abundances of ice-core organic tracers, likely representing significant decreases (increases) in the atmospheric loading of carbonaceous aerosols, occur during colder (warmer) phases in the high latitudinal Northern Hemisphere. This raises questions about causality and possible carbonaceous aerosol feedback mechanisms. Our work opens new avenues for ice core research. Translating concentrations of organic tracers (μg/kg-ice or TOC) from ice-cores, into estimates of the atmospheric loading of carbonaceous aerosols (μg/m³) combined with new model constraints on the strength and sign of climate forcing by carbonaceous aerosols should be a priority for future research.

Reliable quantification of phthalates in environmental matrices (air, water, sludge, sediment and soil): a review

Because of their widespread application, phthalates or phthalic acid esters (PAEs) are ubiquitous in the environment. Their presence has attracted considerable attention due to their potential impacts on ecosystem functioning and on public health, so their quantification has become a necessity. Various extraction procedures as well as gas/liquid chromatography and mass spectrometry detection techniques are found as suitable for reliable detection of such compounds. However, PAEs are ubiquitous in the laboratory environment including ambient air, reagents, sampling equipment, and various analytical devices, that induces difficult analysis of real samples with a low PAE background. Therefore, accurate PAE analysis in environmental matrices is a challenging task. This paper reviews the extensive literature data on the techniques for PAE quantification in natural media. Sampling, sample extraction/pretreatment and detection for quantifying PAEs in different environmental matrices (air, water, sludge, sediment and soil) have been reviewed and compared. The concept of "green analytical chemistry" for PAE determination is also discussed. Moreover useful information about the material preparation and the procedures of quality control and quality assurance are presented to overcome the problem of sample contamination and these encountered due to matrix effects in order to avoid overestimating PAE concentrations in the environment.

Fluorescent water-soluble organic aerosols in the High Arctic atmosphere

Organic aerosols are ubiquitous in the earth's atmosphere. They have been extensively studied in urban, rural and marine environments. However, little is known about the fluorescence properties of water-soluble organic carbon (WSOC) or their transport to and distribution in the polar regions. Here, we present evidence that fluorescent WSOC is a substantial component of High Arctic aerosols. The ratios of fluorescence intensity of protein-like peak to humic-like peak generally increased from dark winter to early summer, indicating an enhanced contribution of protein-like organics from the ocean to Arctic aerosols after the polar sunrise. Such a seasonal pattern is in agreement with an increase of stable carbon isotope ratios of total carbon (δCTC) from -26.8‰ to -22.5‰. Our results suggest that Arctic aerosols are derived from a combination of the long-range transport of terrestrial organics and local sea-to-air emission of marine organics, with an estimated contribution from the latter of 8.7-77% (mean 45%).

Occurrence, fate, behavior and ecotoxicological state of phthalates in different environmental matrices

Because of their large and widespread application, phthalates or phthalic acid esters (PAEs) are ubiquitous in all the environmental compartements. They have been widely detected throughout the worldwide environment. Indoor air where people spend 65-90% of their time is also highly contaminated by various PAEs released from plastics, consumer products as well as ambient suspended particulate matter. Because of their widespread application, PAEs are the most common chemicals that humans are in contact with daily. Based on various exposure mechanisms, including the ingestion of food, drinking water, dust/soil, air inhalation and dermal exposure the daily intake of PAEs may reach values as high as 70 μg/kg/day. PAEs are involved in endocrine disrupting effects, namely, upon reproductive physiology in different species of fish and mammals. They also present a variety of additional toxic effects for many other species including terrestrial and aquatic fauna and flora. Therefore, their presence in the environment has attracted considerable attention due to their potential impacts on ecosystem functioning and on public health. This paper is a synthesis of the extensive literature data on behavior, transport, fate and ecotoxicological state of PAEs in environmental matrices: air, water, sediment, sludge, wastewater, soil, and biota. First, the origins and physicochemical properties of PAEs that control the behavior, transport and fate in the environment are reviewed. Second, the compilation of data on transport and fate, adverse environmental and human health effects, legislation, restrictions, and ecotoxicological state of the environment based on PAEs is presented.

Molecular markers in ambient aerosol in the Mahanadi Riverside Basin of eastern central India during winter

Organic molecular markers are important atmospheric constituents. Their formation and sources are important aspects of the study of urban and rural air quality. We collected PM10 aerosol samples from the Mahanadi Riverside Basin (MRB), a rural part of eastern central India, during the winter of 2011. PM10 aerosols were characterized for molecular markers using ion chromatography. The concentration of PM10 ranged from 208.8 to 588.3 μg m(-3) with a mean concentration of 388.9 μg m(-3). Total concentration of anhydrosugars, sugar alcohols, primary sugars, and oxalate were found to be 3.25, 5.60, 10.52, and 0.37 μg m(-3), respectively, during the study period. Glucose was the most abundant species followed by levoglucosan and mannitol. Significant positive correlation between the molecular markers, anhydrosugars, sugar alcohols, primary sugars, and oxalic acid confirmed that biomass burning, biogenic activity, and re-suspension of soil particles were the main sources of aerosol in the eastern central India study area.

Levoglucosan indicates high levels of biomass burning aerosols over oceans from the Arctic to Antarctic

Biomass burning is known to affect air quality, global carbon cycle, and climate. However, the extent to which biomass burning gases/aerosols are present on a global scale, especially in the marine atmosphere, is poorly understood. Here we report the molecular tracer levoglucosan concentrations in marine air from the Arctic Ocean through the North and South Pacific Ocean to Antarctica during burning season. Levoglucosan was found to be present in all regions at ng/m³ levels with the highest atmospheric loadings present in the mid-latitudes (30°–60° N and S), intermediate loadings in the Arctic, and lowest loadings in the Antarctic and equatorial latitudes. As a whole, levoglucosan concentrations in the Southern Hemisphere were comparable to those in the Northern Hemisphere. Biomass burning has a significant impact on atmospheric Hg and water-soluble organic carbon (WSOC) from pole-to-pole, with more contribution to WSOC in the Northern Hemisphere than in the Southern Hemisphere.

Molecular markers of biomass burning in arctic aerosols

Biomass burning is one of the most important sources of organic matter in the atmosphere as it affects the absorption and scattering of solar radiation, creates cloud condensation nuclei and possibly influences ice and snow albedo. Here we created and validated an analytical method using HPLC/(-)-ESI-MS/MS to determine phenolic compounds (PCLCs): vanillic acid, isovanillic acid, homovanillic acid, syringic acid, syringaldehyde, ferulic acid, p-coumaric acid, and coniferyl aldehyde at trace levels in particulate matter. We analyzed eighteen high-volume air samples from Ny Ålesund (Svalbard) collected during the boreal spring and summer of 2010. Biomass burning molecules including PCLCs (<0.49 μm, mean atmospheric concentration 6 pg m(-3)), levoglucosan (0.004 to 0.682 ng m(-3)) and acrylamide (32 fg m(-3) to 166 fg m(-3)) were present in the sampled aerosols. Levoglucosan concentrations, an unambiguous cellulose combustion tracer, derived from 2010 Russian fires. PCLCs levels in the Ny Alesund atmosphere in different size fractions reflected both long-range transport linked to biomass burning and a terrigenous local source.

Impacts of Siberian biomass burning on organic aerosols over the North Pacific Ocean and the Arctic: primary and secondary organic tracers

During the 2003 Chinese Arctic Research Expedition (CHINARE2003) from the Bohai Sea to the high Arctic (37°N-80°N), filter-based particle samples were collected and analyzed for tracers of primary and secondary organic aerosols (SOA) as well as water-soluble organic carbon (WSOC). Biomass burning (BB) tracer levoglucosan had comparatively much higher summertime average levels (476 ± 367 pg/m(3)) during our cruise due to the influence of intense forest fires then in Siberia. On the basis of 5-day back trajectories, samples with air masses passing through Siberia had organic tracers 1.3-4.4 times of those with air masses transporting only over the oceans, suggesting substantial contribution of continental emissions to organic aerosols in the marine atmosphere. SOA tracers from anthropogenic aromatics were negligible or not detected, while those from biogenic terpenenoids were ubiquitously observed with the sum of SOA tracers from isoprene (623 ± 414 pg/m(3)) 1 order of magnitude higher than that from monoterpenes (63 ± 49 pg/m(3)). 2-Methylglyceric acid as a product of isoprene oxidation under high-NOx conditions was dominant among SOA tracers, implying that these BSOA tracers were not formed over the oceans but mainly transported from the adjacent Siberia where a high-NOx environment could be induced by intense forest fires. The carbon fractions shared by biogenic SOA tracers and levoglucosan in WSOC in our ocean samples were 1-2 orders of magnitude lower than those previously reported in continental samples, BB emissions or chamber simulation samples, largely due to the chemical evolution of organic tracers during transport. As a result of the much faster decline in levels of organic tracers than that of WSOC during transport, the trace-based approach, which could well reconstruct WSOC using biogenic SOA and BB tracers for continental samples, only explained ∼4% of measured WSOC during our expedition if the same tracer-WSOC or tracer-SOC relationships were applied.

Tropospheric aerosols: size-differentiated chemistry and large-scale spatial distributions

Worldwide interest in atmospheric aerosols has emerged since the late 20th century as a part of concerns for air pollution and radiative forcing of the earth's climate. The use of aircraft and balloons for sampling and the use of remote sensing have dramatically expanded knowledge about tropospheric aerosols. Our survey gives an overview of contemporary tropospheric aerosol chemistry based mainly on in situ measurements. It focuses on fine particles less than 1-2.5 microm in diameter. The physical properties of particles by region and altitude are exemplified by particle size distributions, total number and volume concentration, and optical parameters such as extinction coefficient and aerosol optical depth. Particle chemical characterization is size dependent, differentiated by ubiquitous sulfate, and carbon, partially from anthropogenic activity. Large-scale particle distributions extend to intra- and intercontinental proportions involving plumes from population centers to natural disturbances such as dust storms and vegetation fires. In the marine environment, sea salt adds an important component to aerosols. Generally, aerosol components, most of whose sources are at the earth's surface, tend to dilute and decrease in concentration with height, but often show different (layered) profiles depending on meteorological conditions. Key microscopic processes include new particle formation aloft and cloud interactions, both cloud initiation and cloud evaporation. Measurement campaigns aloft are short term, giving snapshots of inherently transient phenomena in the troposphere. Nevertheless, these data, combined with long-term data at the surface and optical depth and transmission observations, yield a unique picture of global tropospheric particle chemistry.

Ubiquity of bisphenol A in the atmosphere

Bisphenol A (BPA) is a suspected endocrine disruptor in the environment. However, little is known about its distribution and transport in the atmosphere. Here, the concentrations of BPA in the atmospheric aerosols from urban, rural, marine, and the polar regions were measured using solvent extraction/derivatization and gas chromatography/mass spectrometry technique. The concentrations of BPA (1-17,400 pg m(-3)) ranged over 4 orders of magnitude in the world with a declining trend from the continent (except for the Antarctica) to remote sites. A positive correlation was found between BPA and 1,3,5-triphenylbenzene, a tracer for plastic burning, in urban regions, indicating that the open burning of plastics in domestic waste should be a significant emission source of atmospheric BPA. Our results suggest that the ubiquity of BPA in the atmosphere may raise a requirement for the evaluation of health effects of BPA in order to control its emission sources, for example, from plastic burning.

Distribution of n-alkanes in the Northern Italy aerosols: data handling of GC-MS signals for homologous series characterization

The paper describes the characterization of n-alkane homologous series present in PM samples performed by gas chromatography-mass spectrometry analysis. The PM samples were collected in three locations in northern Italy: Milan, a large urban area, Oasi Bine, a rural site far from big city centers, and Alpe San Colombano, a remote, high altitude site in the Alps. They represent different particle sizes (PM(1), PM(2.5), PM(10)) and seasons (summer, fall, and winter). The analyzed samples were characterized in terms of PM total mass, total concentration of C(20)-C(32) n-alkanes and carbon preference index, CPI, to quantify the relative abundance of odd versus even n-alkanes. As alternative to the conventional method based on peak integration, a chemometric approach based on autocovariance function (EACVF) computation was found reliable to characterize the homologous series. In particular two parameters have proven useful chemical markers for tracking the biogenic and anthropogenic origins of n-alkanes: CPI(EACVF) and series %, estimating the % n-alkanes abundance relative to total alkane concentration. The investigated samples display a large variation in the n-alkanes relative abundance: the lowest values (series % = 1-14%) were found in summer and the highest (series % = 24-48%) in winter. In addition, a considerable seasonal variation of CPI(EACVF) values can be identified for all the sampling sites: the CPI(EACVF) values are close to 1 (CPI(EACVF) = 0.8-1.2) in the cold seasons, revealing a strong contribution from anthropogenic emissions, while spreader values (CPI(EACVF) = 0.9-3) were found in the warm season, that is, reflecting a variable contribution from biogenic sources in combination with anthropogenic emissions.

Sources and pathways of polycyclic aromatic hydrocarbons transported to Alert, the Canadian High Arctic

A probabilistic function (integrated source contribution function, ISCF) based on backward air mass trajectory calculation was developed to track sources and atmospheric pathways of polycyclic aromatic hydrocarbons (PAHs) to the Canadian High Arctic station of Alert. In addition to the movement of air masses, the emission intensities at the sources and the major processes of partition, indirect photolysis, and deposition occurring on the way to the Arctic were incorporated into the ISCF. The predicted temporal trend of PAHs at Alert was validated by measured PAH concentrations throughout 2004. The PAH levels in the summer are orders of magnitude lower than those in the winter and spring when long-range atmospheric transport events occur more frequently. PAHs observed at Alert are mostly from East Asia (including Russia Far East), North Europe (including European Russia), and North America. These sources account for 25, 45, and 27% of PAHs atmospheric level at Alert, respectively. Source regions and transport pathways contributing to the PAHs contamination in the Canadian High Arctic vary seasonally. In the winter, Russia and Europe are the major sources. PAHs from these sources travel eastward and turn to the north at approximately 120 degrees E before reaching Alert, in conjunction with the well-known Arctic haze events. In the spring, PAHs from Russia and Europe first migrate to the west and then turn to the north at 60 degrees W toward Alert. The majority of PAHs in the summer are from northern Canada where they are carried to Alert via low-level transport pathways. In the fall, 70% of PAHs arriving at Alert are delivered from North American sources.