| 11. |
- Marshall, John
(författare)
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Can tree-ring chemistry be used to monitor atmospheric nanoparticle contamination over time?
- 2022
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 268
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Tidskriftsartikel (refereegranskat)abstract
- Industrial activities and human population growth have resulted in an unprecedented increase in the release of particulate matter (PM) into the environment. Nanoparticle (NP) contamination is widespread and affects all terrestrial and aquatic ecosystems, putting humans and environment at risk. Several studies on the impact of PM and NPs on human health have been conducted over the past two decades, but their effects on plants are still poorly understood. What happens to them in forest ecosystems and trees has yet to be explored. In this paper, we review the literature on the capacity of trees to be used as bioindicators and proxy recorders of past air pollution events. Current research indicates that ultrafine particles can be taken up and translocated to different parts of a tree by physical and chemical processes, as we present studies of plant uptake and translocation processes of NPs in trees. Tree-ring chemistry, i.e., dendrochemistry, has been successfully used to reconstruct trace metal deposition from a variety of sources of pollution, including cars, metal refineries and coal burning. The use of dendrochemistry in environmental monitoring seems promising particularly given the presence of recent development of analytical tools, and is likely to provide useful data on atmospheric NP contamination that could not be obtained from any other source. However, still relatively little is known about the dynamic relationships between NPs and trees. We therefore discuss what future dendrochemical research is needed to make den-drochemical analyses as accurate as possible for monitoring atmospheric nanoparticle contamination over time.
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| 12. |
- Nøjgaard, J. K., et al.
(författare)
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A local marine source of atmospheric particles in the High Arctic
- 2022
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 285
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Tidskriftsartikel (refereegranskat)abstract
- The chemical composition of non-refractory submicron aerosol (NR-PM1) was characterized at the Villum Research Station (Villum) at Station Nord in North Greenland during spring-summer 2016 using a Time of Flight Aerosol Chemical Speciation Monitor (ToF-ACSM). The composition is dominated by sulfate (48%) and organic species (40%). Positive Matrix Factorization (PMF) identified three key factors corresponding to a primary hydrocarbon-like organic aerosol (HOA), and two types of secondary organic aerosol: oxygenated organic aerosol (OOA) and a marine organic aerosol (MOA). The HOA factor accounts for 5% of the organic aerosol mass, which is consistent with previous findings at Villum. The OOA factor accounts for 77% of the organic aerosol mass and correlates with accumulation mode particles, which supports previous findings indicating that oxidized organic aerosols are predominantly from long-range transport during winter and spring at Villum. The MOA factor was characterized by mass spectral fragments of methane sulfonic acid (MSA) from atmospheric oxidation of dimethyl sulfide, for which reason the MOA factor is considered to be of biogenic origin. MOA accounts for 18% of the organic aerosol mass and correlates with locally produced Aitken mode particles. This indicates that biogenic processes are not only a significant source of aerosols at Villum, but MOA also appears to be formed in the vicinity of the measurement site. This local geographical origin was confirmed through air mass back trajectory modelling and source-receptor analysis. During May, air masses frequently arrived from the east, with source regions for the MOA factor and therewith MSA located in the Barents Sea and Lincoln Sea with lesser contributions from the Greenland Sea. During June, air mass origin shifted to the west, with source regions for the MOA factor and MSA shifting correspondingly to Baffin Bay and the Canadian Arctic Archipelago. While shifting transport patterns between May and June lead to shifting source regions, sea ice likely played a role as well. During May, marginal ice zones were present in the Barents Sea between Svalbard and Franz Josef Land, while during June, sea ice in the northern part of Baffin Bay retreated and sea ice in the Canadian Arctic Archipelago decreased. Although May and June experienced different transport patterns and sea ice conditions, levels of the MOA factor and MSA were similar between the months. This is likely due to similarities between marine biological activities in the Barents Sea and Baffin Bay. This research highlights the complex relationship between transport patterns, sea ice conditions, and atmospheric particle concentrations. Multiyear aerosol chemical composition from several High Arctic sites is encouraged to determine the full effects of ocean-atmosphere interactions and transport patterns on atmospheric aerosol concentrations.
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| 13. |
- Pleijel, Håkan, 1958, et al.
(författare)
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Benefits of the Phytotoxic Ozone Dose (POD) index in dose-response functions for wheat yield loss
- 2022
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 268
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Tidskriftsartikel (refereegranskat)abstract
- A central topic of recent research in ground-level ozone (O3) effects on plants is the shift from exposure based on concentrations to a physiologically more realistic approach based on O3 uptake. Critical test of the evidence for the benefits of the latter approach is of utmost importance for the development of O3 risk assessment. We explored the variability in O3 sensitivity in the wheat response function used for risk assessment by the Convention on Long-Range Transport of Air Pollution (LRTAP). The variation in O3 sensitivity among individual experiments was a factor of six larger when using the concentration-based index AOT40 compared to stomatal O3 uptake based Phytotoxic Ozone Dose (POD). Thus, consideration of environmental variables affecting stomatal conductance, such as solar radiation, air humidity and temperature, explained a substantial part of the variation in O3 response among experiments regardless of cultivar differences. Response-functions based on daytime O3 concentrations for the experiments of the POD response function was compared with the corresponding response function including available global data for O3 effects on field grown wheat yield. On average, there was no difference in O3 sensitivity between the two data sets, although the variation in response was substantially larger for global data. We conclude that POD represents a strong improvement over AOT40. The strength and representativeness of the POD approach highlighted is significant for the development and application of models used for risk assessment of ozone impact on crops.
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| 14. |
- Tigabu, Mulualem
(författare)
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Emissions of gaseous pollutants released by forest fire in relation to litter fuel moisture content
- 2022
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 284
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Tidskriftsartikel (refereegranskat)abstract
- The moisture content of forest floor fuel influences fire initiation and spread, but little is known about its impact on the emissions of pollutants. This study aimed to estimate quantitatively the characteristic change of pollutants emitted by forest fires at various fuel moisture content. Thus, litter fuel (both branches and leaves) of two dominant coniferous species (Cunninghamia lanceolata and Pinus massoniana) and two dominant broad-leaved species (Eucalyptus robusta and Cinnamomum camphora) in Southeast China were experimentally burned in an indoor biomass combustion facility, and smoke and non-methane hydrocarbons (NMHCs) were analyzed by gas chromatography-mass spectrometry. The results showed that CO, CO2, NOx, and SO(2 )reached peak concentrations faster at low moisture content. However, emission factors of CO increased, whereas emission factors of CO2, NOx, and SO2 decreased as the moisture content of fuels increased. Emission factors of CO, CO2, NOx and SO2 released from combustion of conifer fuels significantly increased with fuel moisture content compared to broadleaved fuels. Total NMHCs emission was positively affected by the fuel moisture content. As the moisture content of the fuels increased, multi-branched and long-chain alkane emissions increased, whereas olefin and aromatic hydrocarbon emissions decreased but emissions of olefins and aromatic hydrocarbons with more branched chains increased. The findings provide valuable insight about the impact of forest fire on atmospheric environment and fire prevention measures.
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| 15. |
- Vechi, Nathalia T., et al.
(författare)
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Ammonia and methane emissions from dairy concentrated animal feeding operations in California, using mobile optical remote sensing
- 2023
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1873-2844 .- 1352-2310. ; 293
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Tidskriftsartikel (refereegranskat)abstract
- Dairy concentrated animal feeding operations (CAFOs) are significant sources of methane (CH4) and ammonia (NH3) emissions in the San Joaquin Valley, California. Optical techniques, namely, remote sensing by Solar Occultation Flux (SOF) and Mobile extractive FTIR (MeFTIR), were used to measure NH3 air column and ground air concentrations of NH3 and CH4, respectively. Campaigns were performed in May and October 2019 and covered 14 dairies located near Bakersfield and Tulare, California. NH3 and CH4 emission rates from single CAFOs averaged 101.9 ± 40.6 kgNH3/h and 437.7 ± 202.0 kgCH4/h, respectively, corresponding to emission factors (EFs) per livestock unit of 9.1 ± 2.7 gNH3/LU/h and 40.1 ± 17.8 gCH4/LU/h. The NH3 emissions had a median standard uncertainty of 17% and an expanded uncertainty (95% Confidence Interval (CI)) of 37%; meanwhile, CH4 emissions estimates had greater uncertainty, median of 25% and 53% (in the 95% CI). Decreasing NH3 to CH4 ratios and NH3 EFs from early afternoon (13:00) to early night (19:00) indicated a diurnal emission pattern with lower ammonia emissions during the night. On average, measured NH3 emissions were 28% higher when compared to daytime emission rates reported in the National Emissions Inventory (NEI) and modeled according to diurnal variation. Measured CH4 emissions were 60% higher than the rates reported in the California Air Resources Board (CARB) inventory. However, comparison with airborne measurements showed similar emission rates. This study demonstrates new air measurement methods, which can be used to quantify emissions over large areas with high spatial resolution and in a relatively short time period. These techniques bridge the gap between satellites and individual CAFOs measurements.
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| 16. |
- Vouitsis, Ilias, et al.
(författare)
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Transport-related airborne nanoparticles : Sources, different aerosol modes, and their toxicity
- 2023
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 301
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Forskningsöversikt (refereegranskat)abstract
- Nanoparticle emissions from transport are of considerable importance because of their dominance in terms of particle number concentration in most urban atmospheres. Nanoparticles may carry toxic substances, posing a serious threat to pedestrians, passengers and residents. The road sector has been studied intensively in both academia and industry and considerable knowledge has already been gathered. Shipping is also a significant source of nanoparticles both at the global and the European level and may be responsible for cardiopulmonary diseases and lung cancer at the global level, while ship emissions are known as one of the least regulated sources of pollutants. Aviation nanoparticle emissions have also received increasing attention in recent years because of the rapid growth of air transport volumes and the expected expansion to meet capacity needs for future years. Exhaust nanoparticle emissions from diesel rail transport are not very well known and only a few sources addressing actual emission rates are available. All modes of transport are sources of non-exhaust nanoparticle number emission associated with the tire, brake, and road/rail surface wear and tear. This paper provides a literature review to identify the different aerosol modes (i.e., primary, delayed primary, and secondary) from each transport source (road, shipping, aviation, rail), in both laboratory and field tests and to explore their toxicity relevance. The review focuses on nanoparticles (<100 nm) and investigates both exhaust and non-exhaust emissions. We present details on nanoparticles produced by transport sources in the urban environment and parameters that influence nanoparticle emissions. Also, we review the potential relationship between the different aerosol modes and their toxicity effects and point out some issues concerning nanoparticle collection for chemical and toxicity characterization. As regards the toxicity part, it is concluded that transport sources emit large number of nanoparticles which may pose a health risk. They can damage the respiratory tract and lungs, thus playing a crucial role in the physiology of pulmonary pathologies. These nanoparticles can also affect other organs, and the cardiovascular, nervous, and reproductive systems. The combination of oxidative stress, mitochondrial damage, inflammation, and activation of apoptosis, are the initiators of the systemic toxicity of nanoparticles, triggered by a unique combination of heavy metals and organic compounds present in combustion products.
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| 17. |
- Yang, Liu, et al.
(författare)
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Exposure to greenness, air pollution and respiratory health among pre-school children in northern China
- 2023
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Ingår i: Atmospheric Environment. - : Elsevier. - 1352-2310 .- 1873-2844. ; 298
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Tidskriftsartikel (refereegranskat)abstract
- Background: Evidence from developed countries on the association between greenspace and childhood respira-tory health has been inconsistent whilst such evidence is largely lacking in the developing world where rapid urbanization is occurring. This study aimed to investigate the associations between surrounding greenness, air pollution and respiratory health among pre-school children in a rapidly developing city in China.Methods: We recruited 2920 pre-school children in Taiyuan city. Greenness exposure was represented by the Normalized Difference Vegetation Index (NDVI) which combined estimations based on a weighted mean that children spend time both in kindergarten and home (75% home, 25% kindergarten). Air pollution exposures were estimated from a land-use-regression model which was also calculated based on a weighted mean as with greenness. Logistic regression was performed to assess the relationships between greenness, air pollution and respiratory symptoms.Results: Greenness had negatively impacted respiratory health among pre-school children in Taiyuan city, particularly for current dry cough at night. A 0.1-unit increment for NDVI300m was associated with an Odds Ratio (OR) of 2.45 (95%CI: 1.33-4.53) for dry cough at night. The associations were robust after adjusting for air pollution and road condition. No statistically significant associations were found between air pollution and any symptoms. The mediating effect of air pollution on dry cough at night with greenness was not observed.Conclusion: Our study found that within different buffers, a higher level of greenness was consistently associated with a higher risk of dry cough at night among pre-school children. This finding has indicated that environmental policies on urban greening should be scientifically justified to protect respiratory health among young children.
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| 18. |
- Yi, Xin, et al.
(författare)
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Compound-specific radiocarbon analysis of benzene polycarboxylic acids for source apportionment of polyaromatic organic matter in ambient aerosols
- 2023
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Ingår i: Atmospheric Environment. - 1352-2310 .- 1873-2844. ; 307
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Tidskriftsartikel (refereegranskat)abstract
- Polyaromatic organic matter (POM) is an important group of pollutants and light absorbers in ambient aerosols, which consists of a wide range of chemicals with fused benzene rings. POM in ambient aerosols is mainly derived from the incomplete combustion of fossil fuel and biomass. Source apportionment of POM is crucial for advising efficient mitigation of anthropogenic emissions, but that is a challenge due to the complicated composition of POM and ambient aerosols. Benzene polycarboxylic acids (BPCAs) have recently been introduced as molecular markers of atmospheric POM. Compound-specific radiocarbon analysis of BPCAs is expected to be a powerful tool for apportioning fossil sources and contemporary (i.e., biomass burning) sources of POM in ambient aero-sols, yet this application is still lacking. We developed a method for radiocarbon analysis of BPCAs substituted with 3-6 carboxylic groups (B6CA, B5CA, B4CAs and B3CAs). BPCAs were isolated with preparative liquid chromatography with high recoveries (>= 85%). The method is validated with reference materials with fossil and contemporary radiocarbon signatures. Successful radiocarbon analysis of BPCAs was achieved for these reference materials after correcting for the presence of average blanks (B6CA: 1.2 +/- 0.2 mu g, B5CA: 2.3 +/- 0.6 mu g, individual B4CAs: 2.7 +/- 0.2 mu g and individual B3CAs: 6.9 +/- 0.7 mu g). Source apportionment of POM based on radiocarbon
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