| 61. |
- Watne, Ågot, 1983, et al.
(författare)
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Fresh and Oxidized Emissions from In-Use Transit Buses Running on Diesel, Biodiesel, and CNG
- 2018
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 52:14, s. 7720-7728
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Tidskriftsartikel (refereegranskat)abstract
- The potential effect of changing to a nonfossil fuel vehicle fleet was investigated by measuring primary emissions (by extractive sampling of bus plumes) and secondary mass formation, using a Gothenburg Potential Aerosol Mass (Go:PAM) reactor, from 29 in-use transit buses. Regarding fresh emissions, diesel (DSL) buses without a diesel particulate filter (DPF) emitted the highest median mass of particles, whereas compressed natural gas (CNG) buses emitted the lowest ((EFPM)-E-Md 514 and 11 mg kg(fuel)(-1) respectively). Rapeseed methyl ester (RME) buses showed smaller (EFPM)-E-Md and particle sizes than DSL buses. DSL (no DPF) and hybrid-electric RME (RMEHEV) buses exhibited the highest particle numbers ((EFPN)-E-Md 12 X 10(14) # kg(fuel)(-1)). RMEHEv buses displayed a significant nucleation mode (D-p < 20 nm). EFPN of CNG buses spanned the highest to lowest values measured. Low (EFPN)-E-Md and (EFPM)-E-Md were observed for a DPF-equipped DSL bus. Secondary particle formation resulting from exhaust aging was generally important for all the buses (79% showed an average EFPM:AGED/EF(PM)(:FRE)s H ratio >10) and fuel types tested, suggesting an important nonfuel dependent source. The results suggest that the potential for forming secondary mass should be considered in future fuel shifts, since the environmental impact is different when only considering the primary emissions.
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| 62. |
- Ericson Jogsten, Ingrid, 1980-
(författare)
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Assessment of human exposure to per- and polyfluorinated compounds (PFCs) : exposure through food, drinking water, house dust and indoor air
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Per- and polyfluorinated compounds (PFCs) are detected in humans worldwide but all sources of human exposure have not been fully characterized. The aim of this thesis was to evaluate the contributions from food, water, air and dust as sources for human PFC exposure in the general population. Per- and polyfluorinated compounds (PFCs) are detected in humans worldwide but all sources of Up to 27 PFCs were determined at trace levels in blood (ng/mL), water (ng/L), foods (ng/g), dust (ng/g) and air (pg/m3) in a selected Catalan population and PFC intake was estimated from the measured PFC concentrations of the different sources of exposure. The major compounds detected in human blood of the studied population were perfluorooctane sulfonate (PFOS; 7.6 ng/mL), perfluorohexane sulfonate (PFHxS; 3.6 ng/mL) and perfluorooctanoic acid (PFOA; 1.8 ng/mL). In general, PFOS was also the major compound detected in most sources of exposure. Food was found to be the dominant pathway for human PFC exposure accounting for more than 70 % of the total intake of both PFOS and PFOA. In the most populated area (the Barcelona Province) where the highest levels were measured, tap water can contribute to the total exposure substantially with more than 50 % for adults. Indoor sources were negligible in the selected area for most PFCs when compared to food and water intake, except for toddlers under a worst case scenario where contribution from dust and food intake were equal (19 %). Pharmacokinetic (PK) modelling resulted in exposure of 103 ng PFOS/day and 33 ng PFOA/day of adults from the internal PFC blood concentrations. This agrees well with the intake estimated from external exposure through food, drinking water, house dust and indoor air of 80 ng PFOS/day and 32 ng PFOA/day and evidently all major exposure sources for the general population were included (in this study).
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| 63. |
- Zhou, L. Y., et al.
(författare)
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Emissions and Secondary Formation of Air Pollutants from Modern Heavy-Duty Trucks in Real-World Traffic-Chemical Characteristics Using On-Line Mass Spectrometry
- 2021
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 55:21, s. 14515-14525
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Tidskriftsartikel (refereegranskat)abstract
- Complying with stricter emissions standards, a new generation of heavy-duty trucks (HDTs) has gradually increased its market share and now accounts for a large percentage of on-road mileage. The potential to improve air quality depends on an actual reduction in both emissions and subsequent formation of secondary pollutants. In this study, the emissions in real-world traffic from Euro VI-compliant HDTs were compared to those from older classes, represented by Euro V, using high-resolution time-of-flight chemical ionization mass spectrometry. Gas-phase primary emissions of several hundred species were observed for 70 HDTs. Furthermore, the particle phase and secondary pollutant formation (gas and particle phase) were evaluated for a number of HDTs. The reduction in primary emission factors (EFs) was evident (similar to 90%) and in line with a reduction of 28-97% for the typical regulated pollutants. Secondary production of most gas- and particle-phase compounds, for example, nitric acid, organic acids, and carbonyls, after photochemical aging in an oxidation flow reactor exceeded the primary emissions (EFAged/EFFresh ratio >= 2). Byproducts from urea-selective catalytic reduction systems had both primary and secondary sources. A non-negative matrix factorization analysis highlighted the issue of vehicle maintenance as a remaining concern. However, the adoption of Euro VI has a significant positive effect on emissions in real-world traffic and should be considered in, for example, urban air quality assessments.
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| 64. |
- Khalaf, Hazem, et al.
(författare)
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Diastereomers of the Brominated Flame Retardant 1,2-dibromo-4-(1,2 dibromoethyl)cyclohexane Induce Androgen Receptor Activation in the HepG2 Hepatocellular Carcinoma Cell Line and the LNCaP Prostate Cancer Cell Line
- 2009
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Ingår i: Journal of Environmental Health Perspectives. - : National Institute of Environmental Health Science. - 0091-6765 .- 1552-9924. ; 117:12, s. 1853-1859
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Tidskriftsartikel (refereegranskat)abstract
- Background: Reported incidences of prostate cancer and masculinization of animals indicate a release of compounds with androgenic properties into the environment. Large numbers of environmental pollutants have been screened to identify such compounds; however, not until recently was 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH) identified as the first potent activator of the human androgen receptor (hAR). TBECH has been found in beluga whales and bird eggs and has also been found to be maternally transferred in zebrafish.Objectives: In the present study we investigated interaction energies between TBECH diastereomers (α, β, γ, and δ) and the hAR, and their ability to activate the receptor and induce prostate-specific antigen (PSA) expression in vitro.Methods: We performed computational modeling to determine interaction energies between the ligand and the AR ligand-binding site, and measured in vitro competitive binding assays for AR by polarization fluorometry analysis. We used enzyme-linked immunosorbent assays to determine PSA activity in LNCaP and HepG2 cells.Results: We found the γ and δ diastereomers to be more potent activators of hAR than the α and β diastereomers, which was confirmed in receptor binding studies. All TBECH diastereomers induced PSA expression in LNCaP cells even though the AR present in these cells is mutated (T877A). Modeling studies of LNCaP AR revealed that TBECH diastereomers bound to the receptor with a closer distance to the key amino acids in the ligand-binding domain, indicating stronger binding to the mutated receptor.Conclusions: The present study demonstrates the ability of TBECH to activate the hAR, indicating that it is a potential endocrine disruptor.
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| 65. |
- Nilsson, Helena, 1974-, et al.
(författare)
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Inhalation exposure to fluorotelomer alcohols yield perfluorocarboxylates in human blood?
- 2010
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 44:19, s. 7717-7722
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Tidskriftsartikel (refereegranskat)abstract
- Levels of perfluorinated carboxylates (PFCAs) in different environmental and biological compartments have been known for some time, but the routes of exposure still remain unclear. The opinions are divergent whether the exposure to general populations occurs mainly indirect through precursor compounds or direct via PFCAs. Previous results showed elevated blood levels of PFCAs in ski wax technicians compared to a general population. The objective of this follow-up study was to determine concentrations of PFCAs, perfluorosulfonates (PFSAs), and fluorotelomer alcohols (FTOHs), precursor compounds that are known to degrade to PFCAs, in air collected in the breathing zone of ski wax technicians during work. We collected air samples by using ISOLUTE ENV+ cartridges connected to portable air pumps with an air flow of 2.0 L min(-1). PFCAs C5-C11 and PFSAs C4, C6, C8, and C10 were analyzed using LC-MS/MS and FTOHs 6:2, 8:2, and 10:2 with GC-MS/MS. The results show daily inhalation exposure of 8:2 FTOH in mu g/m(3) air which is up to 800 times higher than levels of PFOA with individual levels ranging between 830-255000 ng/m(3) air. This suggests internal exposure of PFOA through biotransformation of 8:2 FTOH to PFOA and PFNA in humans.
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| 66. |
- McFiggans, Gordon, et al.
(författare)
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Secondary organic aerosol reduced by mixture of atmospheric vapours
- 2019
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 565:7741, s. 587-593
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Tidskriftsartikel (refereegranskat)abstract
- Secondary organic aerosol contributes to the atmospheric particle burden with implications for air quality and climate. Biogenic volatile organic compounds such as terpenoids emitted from plants are important secondary organic aerosol precursors with isoprene dominating the emissions of biogenic volatile organic compounds globally. However, the particle mass from isoprene oxidation is generally modest compared to that of other terpenoids. Here we show that isoprene, carbon monoxide and methane can each suppress the instantaneous mass and the overall mass yield derived from monoterpenes in mixtures of atmospheric vapours. We find that isoprene 'scavenges' hydroxyl radicals, preventing their reaction with monoterpenes, and the resulting isoprene peroxy radicals scavenge highly oxygenated monoterpene products. These effects reduce the yield of low-volatility products that would otherwise form secondary organic aerosol. Global model calculations indicate that oxidant and product scavenging can operate effectively in the real atmosphere. Thus highly reactive compounds (such as isoprene) that produce a modest amount of aerosol are not necessarily net producers of secondary organic particle mass and their oxidation in mixtures of atmospheric vapours can suppress both particle number and mass of secondary organic aerosol. We suggest that formation mechanisms of secondary organic aerosol in the atmosphere need to be considered more realistically, accounting for mechanistic interactions between the products of oxidizing precursor molecules (as is recognized to be necessary when modelling ozone production).
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| 67. |
- Tsiligiannis, Epameinondas, et al.
(författare)
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Effect of NOx on 1,3,5-trimethylbenzene (TMB) oxidation product distribution and particle formation
- 2019
-
Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 19:23
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Tidskriftsartikel (refereegranskat)abstract
- Secondary organic aerosol (SOA) represents a significant fraction of the tropospheric aerosol and its precursors are volatile organic compounds (VOCs). Anthropogenic VOCs (AVOC) dominate the VOC budget in many urban areas with 1,3,5-trimethylbenzene (TMB) being among the most reactive aromatic AVOCs. TMB formed highly oxygenated organic molecules (HOMs) in an NOx-free environment, which could contribute to new particle formation (NPF) depending on oxidation conditions where elevated OH oxidation enhanced particle formation. The experiments were performed in an oxidation flow reactor, the Go:PAM unit, under controlled OH oxidation conditions. By addition of NOx to the system we investigated the effect of NOx on particle formation and on the product distribution. We show that the formation of HOMs, and especially HOM accretion products, strongly varies with NOx conditions. We observe a suppression of HOM and particle formation with increasing NOx/ΔTMB ratio and an increase in the formation of organonitrates (ONs) mostly at the expense of HOM accretion products. We propose reaction mechanisms and pathways that explain the formation and observed product distributions with respect to oxidation conditions. We hypothesise that, based on our findings from TMB oxidation studies, aromatic AVOCs may not contribute significantly to NPF under typical NOx/AVOC conditions found in urban atmospheres.
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| 68. |
- Wang, Xuan, et al.
(författare)
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Effects of Anthropogenic Chlorine on PM2.5 and Ozone Air Quality in China
- 2020
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 54:16, s. 9908-9916
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Tidskriftsartikel (refereegranskat)abstract
- China has large anthropogenic chlorine emissions from agricultural fires, residential biofuel, waste incineration, coal combustion, and industrial processes. Here we quantify the effects of chlorine on fine particulate matter (PM2.5) and ozone air quality across China by using the GEOS-Chem chemical transport model with comprehensive anthropogenic emissions and detailed representation of gas-phase and heterogeneous chlorine chemistry. Comparison of the model to observed ClNO2, HCl, and particulate Cl- concentrations shows that reactive chlorine in China is mainly anthropogenic, unlike in other continental regions where it is mostly of marine origin. The model is successful in reproducing observed concentrations and their distributions, lending confidence in the anthropogenic chlorine emission estimates and the resulting chemistry. We find that anthropogenic chlorine emissions increase total inorganic PM2.5 by as much as 3.2 μg m-3 on an annual mean basis through the formation of ammonium chloride, partly compensated by a decrease of nitrate because ClNO2 formation competes with N2O5 hydrolysis. Annual mean MDA8 surface ozone increases by up to 1.9 ppb, mainly from ClNO2 chemistry, while reactivities of volatile organic compounds increase (by up to 48% for ethane). We find that a sufficient representation of chlorine chemistry in air quality models can be obtained from consideration of HCl/Cl- thermodynamics and ClNO2 chemistry, because other more complicated aspects of chlorine chemistry have a relatively minor effect.
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| 69. |
- Wang, Y. J., et al.
(författare)
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The secondary formation of organosulfates under interactions between biogenic emissions and anthropogenic pollutants in summer in Beijing
- 2018
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 18:14, s. 10693-10713
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Tidskriftsartikel (refereegranskat)abstract
- Organosulfates (OSs) with ambiguous formation mechanisms are a potential source of "missing secondary organic aerosol (SOA)" in current atmospheric models. In this study, we chemically characterized OSs and nitrooxy-OSs (NOSs) formed under the influence of biogenic emissions and anthropogenic pollutants (e.g., NOx, SO42-) in summer in Beijing. An ultrahigh-resolution mass spectrometer equipped with an electrospray ionization source was applied to examine the overall molecular composition of S-containing organics. The number and intensities of S-containing organics, the majority of which could be assigned as OSs and NOSs, increased significantly during pollution episodes, which indicated their importance for SOA accumulation. To further investigate the distribution and formation of OSs and NOSs, high-performance liquid chromatography coupled with mass spectrometry was employed to quantify 10 OSs and 3 NOS species. The total concentrations of quantified OSs and NOSs were 41.4 and 13.8 ng m(-3), respectively. Glycolic acid sulfate was the most abundant species among all the quantified species, followed by monoterpene NOSs (C10H16NO7S-). The total concentration of three isoprene OSs was 14.8 ng m(-3) and the isoprene OSs formed via the HO2 channel were higher than those formed via the NO/NO2 channel. The OS concentration coincided with the increase in acidic sulfate aerosols, aerosol acidity, and liquid water content (LWC), indicating the acid-catalyzed aqueousphase formation of OSs in the presence of acidic sulfate aerosols. When sulfate dominated the accumulation of secondary inorganic aerosols (SIAs; sulfate, nitrate, and ammonium; SO42-/SIA > 0.5), OS formation would obviously be promoted as the increasing of acidic sulfate aerosols, aerosol LWC, and acidity (pH < 2.8). Otherwise, acid-catalyzed OS formation would be limited by lower aerosol acidity when nitrate dominated the SIA accumulation. The nighttime enhancement of monoterpene NOSs suggested their formation via the nighttime NO3-initiated oxidation of monoterpene under high-NOx conditions. However, isoprene NOSs are presumed to form via acid-catalyzed chemistry or reactive uptake of oxidation products of isoprene. This study provides direct observational evidence and highlights the secondary formation of OSs and NOSs via the interaction between biogenic precursors and anthropogenic pollutants (NOx, SO2, and SO42-). The results imply that future reduction in anthropogenic emissions can help to reduce the biogenic SOA burden in Beijing or other areas impacted by both biogenic emissions and anthropogenic pollutants.
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| 70. |
- Kylin, Henrik, et al.
(författare)
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Evaluating threats to an endangered species by proxy : air pollution as threat to the blue swallow (Hirundo atrocaerulea) in South Africa
- 2011
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Ingår i: Environmental Science and Pollution Research. - : Springer. - 0944-1344 .- 1614-7499. ; 18:2, s. 282-290
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Tidskriftsartikel (refereegranskat)abstract
- Background, aim, and scope: The blue swallow (Hirundo atrocaerulea) is one of the most threatened bird species in southern Africa. Among terrestrial birds, its plumage is known to be the most water repellent, an adaptation to foraging on the wing in dense fog. Despite this uniqueadaptation, the nesting success of the blue swallow at the Blue Swallow Natural Heritage Site (BSNHS) is lower during years with high incidence of fog. As the phenomenon is not observed at other nesting sites, we hypothesized that this is due to changes in the air chemistry at the BSNHS. In the immediate proximity of the BSNHS, plantations of exotic trees (e.g., pines and eucalypts), rich in volatile organic compounds (VOCs), are dominant features. In addition, air pollution from the Johannesburg area is transported with the surface winds and mix withVOCs released from exotic trees. Together with the high humidity and high elevation, these conditions may result in the formation of sulphonates. Sulphonates are strong detergents, and the presence of these in the fog could lead to decreased water repellence of the plumage. This study was performed in order to determine the occurrence and distribution of sulphonates in the BSNHS and to compare these with sulphonates formed in other locations in South Africa. Because the blue swallow is endangered, pine needles were used as proxy to detect formation of sulphonates.Methods: We sampled pine needles with different exposure to air pollutants, in climates with different humidity, and at different elevation and analyzed these for sulphonates using mass spectrometry.Results: Pine needles from high elevations and the BSNHS, with high humidity, and exposure to air pollution contained significantly higher concentrations of sulphonates than pine needles from low elevations or from high elevations with a dryer climate or a different combination of air pollutants.Conclusions: These findings lead to two conclusions. First, the occurrence and distribution of sulphonates may be explained by chemical reactions between sulphur dioxide and organic compounds in the humid air induced by ultraviolet radiation. Second, elevated concentrations of sulphonates in the fog could affect the water repellence of the blue swallow plumage, possibly decreasing their capacity to forage in the fog. We cannot prove conclusively that this is the reason why the number of blue swallows atthe BSNHS has decreased dramatically, but for endangered species, we may have to rely on proxies to draw conclusions about outside threats. All such information should be valuable in devising protection plans for species under threat.Recommendations and perspectives: The use of proxies to elucidate threats to endangered species should be evaluated in a broad scale. The mist-belt habitat in general is threatened by many human activities. These findings indicate that air pollution and the proximity of volatile organic compound (VOC) sources close to mist-belt habitat refuges may be an unrecognised conservation threat to the animals inhabiting them.
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