Organic Pollutants In Atmosphere Research Articles

Sources of Wintertime Atmospheric Organic Pollutants in a Large Canadian City: Insights from Particle and Gas Phase Measurements

Sources of Wintertime Atmospheric Organic Pollutants in a Large Canadian City: Insights from Particle and Gas Phase Measurements

Potential Strategy to Control the Organic Components of Condensable Particulate Matter: A Critical Review.

More and more attention has been paid to condensable particulate matter (CPM) since its emissions have surpassed that of filterable particulate matter (FPM) with the large-scale application of ultralow-emission reform. CPM is a gaseous material in the flue stack but instantly turns into particles after leaving the stack. It is composed of inorganic and organic components. Organic components are an important part of CPM, and they are an irritant, teratogenic, and carcinogenic, which triggers photochemical smog, urban haze, and acid deposition. CPM organic components can aggravate air pollution and climate change; therefore, consideration should be given to them. Based on existing methods for removing atmospheric organic pollutants and combined with the characteristics of CPM organic components, we provide a critical overview from the aspects of (i) fundamental cognition of CPM, (ii) common methods to control CPM organic components, and (iii) catalytic oxidation of CPM organic components. As one of the most encouraging methods, catalytic oxidation is discussed in detail, especially in combination with selective catalytic reduction (SCR) technology, to meet the growing demands for multipollutant control (MPC). We believe that this review is inspiring for a fuller understanding and deeper exploration of promising approaches to control CPM organic components.

A level IV fugacity-based multimedia model based on steady-state particle/gas partitioning theory and its application to study the spatio-temporal trends of PBDEs in atmosphere of northeast China

Particle/gas (P/G) partitioning can significantly affect the environmental behavior of atmospheric pollutants. In this study, we established a large-scale level IV fugacity-based multimedia model (the S-L4MF Model) based on the steady-state P/G partitioning theory. The spatial and temporal trends with the atmospheric contamination of polybrominated diphenyl ethers (PBDEs) in northeastern China under various climate conditions were simulated by the model. There is a reasonable agreement between the simulated and measured gaseous and particulate concentrations of 3 selected PBDE congeners (BDE-47, -99 and -209). For BDE-47, -99 and -209, 91.9 %, 94.8 % and 86.2 % of data points in the evaluation of the spatial trend, whereas 97.4 %, 98.2 % and 91.6 % of data points in the evaluation of the temporal trend, exhibit discrepancies between the modeled and measured data within 1 order of magnitude. The S-L4MF Model performed better than the other model with the same configuration but an equilibrium-state P/G partitioning assumption. The sensitivity and uncertainty analysis indicated that the air temperature and hexadecane-air partition coefficient were the dominant influencing factors on atmospheric concentrations. In addition, the model was successfully applied to study the inter-annual and seasonal variations of gaseous and particulate concentrations of the three PBDEs during 1971–2020 in Harbin, a northeastern Chinese city. Finally, we illustrated the potential to use the model to understand P/G partitioning behavior and the effects of snow and ice on atmospheric concentrations. In summary, the S-L4MF Model provided a powerful and effective tool for studying the environmental behavior of atmospheric organic pollutants, especially in cold regions.

Using homing pigeons to monitor atmospheric organic pollutants in a city heavily involving in coal mining industry

Coal is the most extensively used fossil fuel in China. It is well documented that coal combustion detrimentally affected air quality, yet the contribution of coal mining activity to air pollution is still largely unknown. Homing pigeons have been applied to assess the occurrence of atmospheric pollutants within cities. Herein, we sampled homing pigeons from both urban and mining areas in a typical coal industry city (Datong, China) as biomonitors for assessing local air pollution. Target organic contaminants, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and organochlorine pesticides (OCPs) were frequently detected in lung, liver, and fat tissues of the pigeons. The pollutants were predominately accumulated in lung, validating that respiration was the main accumulation route for these compounds in homing pigeons. In addition, pathological damage examination in lung and liver tissues revealed that the exposure to atmospheric pollutants impaired pigeon health. While the concentrations of PCBs and OCPs were similar in pigeons from urban and mining areas, the concentrations of PAHs were higher in pigeons from urban area. In contrast, more elevated levels of PBDEs (particularly BDE-209) were found in the mining area, which was consistent with the greater pathological damages and particulate matter levels. Unlike coal combustion, coal mining activities did not increase atmospheric PAH exposure to homing pigeons, but intensified PBDE contamination along with increasing emission of particulate matters. Overall, homing pigeons are promising biomonitors for assessing the respiratory exposure and risk of atmospheric pollutants within cities.

Evaluating and elucidating the reactivity of OH radicals with atmospheric organic pollutants: Reaction kinetics and mechanisms by machine learning

The rate constants of the reactions of OH radicals with atmospheric organic pollutants (AOPs) are crucial physicochemical parameters to guide in the elucidation of the kinetics and mechanisms of the reactive landscape. The experimental and theoretical difficulties in revealing the reactivity of these degradation processes motivated us to develop a protocol based on machine learning combining molecular fingerprints to estimate their rate constants. The present workflow is based on Organization for Economic Cooperation and Development (OECD) guidelines and state-of-the-art techniques involving (i) data collection including 903 AOPs cataloged in the literature, (ii) pre-processing and structuring of data, (iii) development of models based on three machine learning algorithms, (iv) the standard reference of validation, and (v) mechanistic interpretation. The results show that the built model has a high predictive capacity – Rcv2 > 0.959 and RMSEcv < 0.090 for the training set and Rext2 and Qext2 > 0.889 and RMSEext < 0.084 for the test set. Additionally, through the SHapley Additive exPlanations (SHAP) method, it was possible to establish insight into the contribution of chemical classes to reaction kinetics and mechanism and to discuss it consistently with current experimental and theoretical observations. The availability of the evaluated reaction rate constants permitted to elucidate the role of AOPs in the photochemical ozone balance. Finally, to disseminate use of our results, we have presented them in a user-friendly web application that permits compilation of kinetic parameters, and that permits future implementations to account for the temperature dependence in the environmental relevant range, and the consideration of a wider class of chemicals and processes in the mechanistic networks of atmospheric reactivity.

Passive Air Sampling of PCDD/Fs, PCBs, PAEs, DEHA, and PAHs from Informal Electronic Waste Recycling and Allied Sectors in Indian Megacities.

Xenobiotic chemical emissions from the informal electronic waste recycling (EW) sector are emerging problem for developing countries, with scale and impacts that are yet to be evaluated. We report an intensive polyurethane foam disk passive air sampling study in four megacities in India to investigate atmospheric organic pollutants along five transects viz., EW, information technology (IT), industrial, residential, and dumpsites. Intraurban emission sources were estimated and attributed by trajectory modeling and positive matrix factorization (PMF). ∑17PCDD/Fs, ∑25PCBs, ∑7plasticizers, and ∑15PAHs concentrations ranged from 3.1 to 26 pg/m3 (14 ± 7; Avg ± SD), 0.5-52 ng/m3 (9 ± 12); 7.5-520 ng/m3, (63 ± 107) and 6-33 ng/m3 (17 ± 6), respectively. EW contributed 45% of total PCB concentrations in this study and was evidenced as a major factor by PMF. The dominance of dioxin-like PCBs (dl-PCBs), particularly PCB-126, reflects combustion as the possible primary emission source. PCDD/Fs, PCBs and plasticizers were consistently highest at EW transect, while PAHs were maximum in industrial transect followed by EW. Concentrations of marker plasticizers (DnBP and DEHP) released during EW activities were significantly higher (p < 0.05) in Bangalore than in other cities. Toxic equivalents (TEQs) due to dl-PCBs was maximum in the EW transect and PCB-126 was the major contributor. For both youth and adult, the highest estimated inhalation risks for dl-PCBs and plasticizers were seen at the EW transect in Bangalore, followed by Chennai and New Delhi.

Temporal trends of atmospheric PAHs: Implications for the influence of the clean air action

A significant decline with primary air pollutants has occurred in China since 2013, benefiting from the Clean Air Action. Polycyclic aromatic hydrocarbons (PAHs), as ubiquitous organic pollutants in atmosphere, could also be influenced by the Action. However, related studies are limited in China. In this study, atmospheric PAHs in Harbin from June 2014 to May 2019 were monitored to evaluate the influence of the Action. During this period, significant decreasing trends of Σ15PAHs in the atmosphere were observed. The half-lives for Σ15PAHs in the total phase, gas phase, and particle phase were 3.23 ± 0.370, 2.94 ± 0.295, and 4.27 ± 0.666 years, respectively. These half-lives are shorter than those observed in other long-term monitoring programs worldwide. Furthermore, a stepwise multiple linear regression model used for primary air pollutants was applied to quantify the meteorological contribution to the decreasing trends of atmospheric PAHs. The results indicated that 35% of the decrease could be attributable to meteorological factors. In other words, the Action implementation in Harbin was proved to be the major reason for reducing atmospheric PAHs. In summary, the results observed in the present study demonstrated the effectiveness of the Clean Air Action, not only for decreasing primary air pollutants but also for atmospheric PAHs, which provides new insights into future clean air policies in China and other countries.

Experimental simulation of stratospheric ozone reactions with chloroalkane organic pollutants

Environmental contextChlorinated organic atmospheric pollutants, which can be produced naturally or anthropogenically, are considered as a factor responsible for stratospheric ozone depletion. Based on experimental simulations and low temperature vibrational spectroscopy, this work reports a mechanism for the reaction of chloroalkanes with ozone. This reaction leads to the formation of the photochemically reactive chlorine oxide species. Kinetics and implications of the reactions are discussed. AbstractThe present work deals with the important problem of stratospheric ozone depletion and an investigation of the atmospheric decay of organic pollutants. The products of the heterogeneous reactions of ozone with chloroethane and 1-chloropropane in a flow-through vacuum electric discharge unit under conditions similar those observed in the stratosphere are studied by low-temperature infrared (IR) absorption spectroscopy. Taking into account the literature data, a scheme for the interaction of ozone with halogen-substituted alkanes at low temperatures is proposed, which shows the formation of chlorine oxides that have high photochemical activity and can cause damage to the ozone layer even when present in small concentrations. The conversion of chloroalkanes over time demonstrates the first-order-decay behaviour of the investigated processes.

Fluorescence Characteristics and Source Analysis of DOM in Snowfall of Xi'an

Fluorescence characteristics and sources of dissolved organic matter (DOM) in snowfall in Xi'an were studied by three-dimensional fluorescence spectroscopy, parallel factor analysis, and backward trajectory model, which provided a data basis for the analysis of the chemical composition and source of atmospheric organic pollutants. Results show that the DOC content of DOM was 0.88-10.92 mg·L-1. DOM mainly contained humus-like, fulvic acid-like, tryptophan-like, and tyrosine-like substances. The fluorescence intensity and the summed intensities of these substances exhibited significant positive correlations with the DOC and UV254 (P<0.01). The fluorescence index (FI), biological source index (BIX), and humic index (HIX) values of DOM during snowfall were 1.50-1.75, 0.87-1.25, and 1.11-1.97, respectively. FI was positively correlated with BIX and negatively correlated with HIX (P<0.05). During snowfall, the air mass transmission trajectories included the local transmission, long-distance transmission starting from Xinjiang (through Gansu and Ningxia), and medium-distance transmissions starting from Inner Mongolia (through Ningxia) and Shandong (via Henan), accounting for 38.78%, 24.04%, 19.87%, and 17.31% of the total, respectively. This indicates that the content or relative content of the DOM contained in the precipitation can be characterized by fluorescence intensities and their sums of the humic-like, fulvic acid-like, tryptophan-like, and tyrosine-like tyrosine. The DOM in snowfall had both biological and terrestrial characteristics, and belonged to a self-generated source with the newly produced organic matter or matter with stronger self-source characteristics. Local transmission had the most significant contribution to the source of snowfall DOM.

Leaf-deposited semi-volatile organic compounds (SVOCs): An exploratory study using GCxGC-TOFMS on leaf washing solutions

Airborne particulate matter (PM) includes semi-volatile organic compounds (SVOCs), which can be deposited on vegetation matrices such as plant leaves. In alternative to air-point measurements or artificial passive substrates, leaf monitoring offers a cost-effective, time-integrating means of assessing local air quality. In this study, leaf washing solutions from ivy (Hedera hibernica) leaves exposed during one-month at different land use classes were explored via comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GCxGC-TOFMS). The composition of leaf-deposited SVOCs, corrected for those of unexposed leaves, was compared against routinely monitored pollutants concentrations (PM10, PM2.5, O3, NO2, SO2) measured at co-located air monitoring stations.The first study on leaf-deposited SVOCs retrieved from washing solutions, herein reported, delivered a total of 911 detected compounds. While no significant land use (rural, urban, industrial, traffic, mixed) effects were observed, increasing exposure time (from one to 28 days) resulted in a higher number and diversity of SVOCs, suggesting cumulative time-integration to be more relevant than local source variations between sites. After one day, leaf-deposited SVOCs were mainly due to alcohols, N-containing compounds, carboxylic acids, esters and lactones, while ketones, diketones and hydrocarbons compounds gained relevance after one week, and phenol compounds after one month. As leaf-deposited SVOCs became overall more oxidized throughout exposure time, SVOCs transformation or degradation at the leaf surface is suggested to be an important phenomenon. This study confirmed the applicability of GCxGC-TOFMS to analyze SVOCs from leaf washing solutions, further research should include validation of the methodology and comparison with atmospheric organic pollutants.

Dissolved organic and inorganic matter in bulk deposition of a coastal urban area: An integrated approach

Bulk deposition can remove atmospheric organic and inorganic pollutants that may be associated with gaseous, liquid or particulate phases. To the best of our knowledge, few studies have been carried out, which simultaneously analyse the presence of organic and inorganic fractions in rainwater. In the present work, the complementarity of organic and inorganic data was assessed, through crossing data of some organic [DOC (dissolved organic carbon), absorbance at 250nm (UV250nm), integrated fluorescence] and inorganic [H+, NH4+, NO3−, non sea salt sulphate (NSS-SO42−)] parameters measured in bulk deposition in the coastal urban area of Aveiro. The organic and inorganic parameters analysed were positively correlated (p<0.001) except for H+, which suggests that a constant fraction of chromophoric dissolved organic matter (CDOM) came from anthropogenic sources. Furthermore, the inverse correlations observed for the organic and inorganic parameters with the precipitation amount suggest that organic and inorganic fractions were incorporated into the rainwater partially by below-cloud scavenging of airborne particulate matter. This is in accordance with the high values of DOC and NO3− found in samples associated with marine air masses, which were linked in part to the contribution of local emissions from vehicular traffic. DOC of bulk deposition was the predominant constituent when compared with the constituents H+, NH4+, NO3− and NSS-SO42−, and consequently bulk deposition flux was also highest for DOC, highlighting the importance of DOC and of anthropogenic ions being simultaneously removed from the atmosphere by bulk deposition. However, it was verified that the contribution of anthropogenic sources to the DOC of bulk deposition may be different for distinct urban areas. Thus, it is recommended that organic and inorganic fractions of bulk deposition are studied together.

A simple and rapid analysis for gas-phase polycyclic aromatic hydrocarbons using an organic-solvent-based method

Monitoring of atmospheric organic pollutants is usually conducted by means of active or passive air samplers. In this study, we developed a simple, conventional, economic and fast sampling method for volatile and semivolatile compounds that is based on a liquid-phase organic solvent. Laboratory tests showed the feasibility of the method, and the major parameters of the method, such as temperature, organic solvent, carrier gas and air flow rate, were preliminarily optimized. For 16 kinds of polycyclic aromatic hydrocarbons (PAHs), the recovery, relative standard deviation and detection limit were ranged from 87.0 to 104.4%, 2.6 to 15.6% and 0.08 to 0.45 ng mL−1, respectively. Field application of the new method also showed good sampling efficiency for PAHs in real air samples, comparable to the results with an XAD-2 resin-based method. The similarity was closed to 1, suggesting that the new method is suitable for sampling of volatile and semivolatile organic pollutants in air and has great potential for air-pollution monitoring.

Organic atmospheric pollutants: polycyclic hydrocarbons from coal atmospheric fluidised bed combustion (AFBC)

The work deals with coal combustion in a pilot-plant fluidised bed (7 cm i.d.) under atmospheric conditions.&#x0D; The aims are to capture and analyse qualitatively as well as quantitatively the volatile polycyclic&#x0D; hydrocarbons emitted by using coal as energy source under various combustion conditions. After establishing&#x0D; the sampling procedure, the emissions are caught in five different traps (two cyclones, nylon and&#x0D; teflon filters, and XAD-2). The contribution of each of the sixteen polycyclic aromatic hydrocarbons&#x0D; (PAH) listed by the US Environmental Protection Agency (EPA) as priority pollutants is analysed, and&#x0D; their emissions as a function of the combustion variables (combustion temperature, percentage of&#x0D; excess oxygen, air flow and fluidising agent) are reported. Synchronous Fluorescence Spectroscopy is&#x0D; the analytical tool used for identification and quantification of the PAH emissions.

The role of the global cryosphere in the fate of organic contaminants

Abstract. The cryosphere is an important component of global organic contaminant cycles. Snow is an efficient scavenger of atmospheric organic pollutants while a seasonal snowpack, sea ice, glaciers and ice caps are contaminant reservoirs on time scales ranging from days to millennia. Important physical and chemical processes occurring in the various cryospheric compartments impact contaminant cycling and fate. A variety of interactions and feedbacks also occur within the cryospheric system, most of which are susceptible to perturbations due to climate change. In this article, we review the current state of knowledge regarding the transport and processing of organic contaminants in the global cryosphere with an emphasis on the role of a changing climate. Given the complexity of contaminant interactions with the cryosphere and limitations on resources and research capacity, interdisciplinary research and extended collaborations are essential to close identified knowledge gaps and to improve our understanding of contaminant fate under a changing climate.

Quantitative analysis of atmospheric volatile organic pollutants by thermal desorption gas chromatography mass spectrometry

An analytical method has been developed and validated for analyzing 48 volatile organic compounds (VOCs) that were found to be present in substantial quantities in the atmosphere in Singapore. Air samples were collected by active sampling using Tenax/Carbopack X multisorbent tubes and were evaluated by Thermal Desorption Gas Chromatography Mass Spectrometry (TD-GCMS). Experiments conducted using standards demonstrated excellent repeatability with relative standard deviation (%RSD) values lesser than 10%, good linearity with R2 values of at least 0.99 for a wide range of concentrations between 0.02 and 500 ng, breakthrough values 5% or lower, tube desorption efficiencies close to 100% and good recoveries between 61% and 120%. Sampling volumes and flow rates were tested and selected by evaluating the performance of the multisorbent tubes. 30 mL min−1 was selected as the optimal flow rate for different sampling volumes depending on the individual compound's breakthrough value and reproducibility during air sampling. Most of the target analytes exhibited acceptable breakthrough of 5% or less, reproducibility within 20% deviation and method detection limits below 500 ppbv. Criteria established by the United States Environmental Protection Agency (USEPA) for sorbent tube sampling (EPA TO-17) were met for most compounds of interest.

Evaluation of Asphaltene Degradation on Highly Ordered TiO2 Nanotubular Arrays via Variations in Wettability

Photocatalytic degradation of both aquatic and atmospheric organic pollutants on titanium dioxide has been extensively investigated in the past decades, but research on direct photocatalytic degradation of solid-phase organic pollutants is rather limited. In this work, photocatalytic degradation of n-C(7) asphaltene, which is composed of solid-phase organic substances found in crude oil, on highly ordered TiO(2) nanotubular arrays (TNAs) was studied using the wettability as an indicator. It was observed that the water contact angle rose linearly with increasing the concentration of n-C(7) asphaltene solution up to 0.02 g mL(-1). Further increasing the concentration of n-C(7) asphaltene only caused small augment in the contact angle, which eventually became stable around 98°. It is demonstrated that the water contact angle can be used as an indicator to reflect the residual solid-phase organic pollutants within a certain range of pollutant concentration. As observed, n-C(7) asphaltene film degraded on TNAs under UV illumination for 60 min, showing complete mineralization of ∼80% of n-C(7) asphaltene that was released into air finally. The remaining 20% of asphaltene was partially decomposed into smaller organic molecules, e.g., -C(═O)- and -C(═O)-OH, confirmed by high-resolution X-ray photoelectron spectra analysis. TNAs can be reused to degrade the solid-phase n-C(7) asphaltene for a number of cycles without further treatment.

Intermolecular interactions governing the partition between particulate and gas phases for typical organic pollutants

The partition coefficients between particulate and gas phases (K p) for organic pollutants are of great importance to characterize the behavior of organic pollutants in atmosphere, and are basic data needed by ecological risk assessment. Partial least squares (PLS) regression with 16 theoretical molecular structural descriptors was used to develop polyparameter linear free energy relationship (LFER) model for K p of 18 aliphatic hydrocarbons, 21 polycyclic aromatic hydrocarbons (PAHs), 16 polychlorinated biphenyls (PCBs) and 13 polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs). The obtained model has a good predictive ability and robustness, which can be used for estimating K p of chemicals with similar structures. Intermolecular dispersive interactions play a leading role in governing K p, followed by charge-transfer interactions and hindrance effects of molecular size. The respective models developed for different group compounds imply that the action mechanism is similar, and dipole-dipole and dipole-induced dipole interactions play a minor role in governing K p of n-alkanes, PCBs and PCDD/Fs.

Spatial distribution and seasonal variations of polycyclic aromatic hydrocarbons (PAHs) using semi-permeable membrane devices (SPMD) and pine needles in the Pearl River Delta, South China

Semi-permeable membrane devices (SPMDs) were deployed at 12 sites in the Pearl River Delta (PRD) during 2001–2002 to elucidate the spatial distribution and seasonal variations of polycyclic aromatic hydrocarbons (PAHs) in the subtropical region. Pine needles from the same sites were also analyzed for PAHs for a comparison with SPMDs. In Guangzhou, high volume active air sampling (HiVol) was carried out weekly through out the year-round sampling campaign. The PAHs sequestered in SPMDs (in ng SPMD −1 day −1) were found to be higher in winter than in summer. Using the HiVol data, SPMD sampling rates were calculated seasonally for some dominant gas-phase PAH compounds (Fluorene to Pyrene). These sampling rates ranged from 0.7 to 2.8 m 3 day −1, which were used to determine the atmospheric PAH concentrations at other sites. The calculated PAH concentrations, based on different temperature-dependant SPMD sampling rates, in the air were higher in summer than in winter. The PAH compounds sampled with SPMDs and pine needle were mainly associated with gaseous PAHs, while pine needles accumulated more high molecular weight (HW) PAHs. Good agreements were found in the spatial distribution of atmospheric PAHs measured by SPMDs and pine needles. The potential of using SPMDs for seasonal monitoring of atmospheric organic pollutants at a regional scale was demonstrated.

Adsorption of volatile atmospheric pollutants on an heterogeneous surface of surrogate solid aerosols

Adsorption of 23 nonpolar and polar volatile atmospheric organic pollutants on the surface of silica gel, carbon black (Carbopack), and carbon-coated silica gel (Carbosil), materials imitating mineral and carbonaceous aerosols, was studied by inverse gas chromatography at finite concentrations. The results obtained suggest that the surface is nonuniform. The experimental adsorption isotherms were described within the framework of an approach based on the local Langmuir equation and a rectangular surface area distribution over the adsorption energy. It was established how the mean and variance moments of these distributions depend on the polarizability of the sorbates and their acid-base characteristics and how these parameters influence the adsorption characteristics of the system under study.

Identification and seasonal variation of atmospheric organic pollutants in Campos dos Goytacazes, Brazil

Organic aerosol samples collected during a 1 year study at three sites in the city of Campos dos Goytacazes, Rio de Janeiro, Brazil, were examined by gas chromatography and gas chromatography–mass spectrometry. Samples were acquired using a standard high-volume air sampler (Hi-Vol); extracts prepared and fractionated into aliphatic, aromatic and polar compounds. These compounds were quantified and their seasonal ambient concentration patterns discussed. High winter and low summer concentrations were observed for retene, polycyclic aromatic hydrocarbons and total suspended particulate matter (TSP), with a seasonal (winter) peak for all compounds studied. The higher concentrations observable from May to September may result from crop burning processes, which occur in the sugarcane plantations, mainly during this part of the year. The studied sites may be considered unpolluted as concentrations of benzo[a]pyrene and benzene were lower than the regulation lower limits. On the other hand, two sites were considered polluted by TSP determination.