| 1. |
- Bosch, Carme, et al.
(författare)
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Source Apportionment of Polycyclic Aromatic Hydrocarbons in Central European Soils with Compound-Specific Triple Isotopes (delta C-13, Delta C-14, and delta H-2)
- 2015
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 49:13, s. 7657-7665
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports the first study applying a triple-isotope approach for source apportionment of polycyclic aromatic hydrocarbons (PAHs). The C-13/C-12, and H-2/H-1 isotope ratios of PAHs were determined in forest soils from mountainous areas of the Czech Republic, European Union. Statistical modeling applying a Bayesian Markov chain Monte Carlo (MCMC) framework to the environmental triple isotope PAR data and an end-member PAR isotope database allowed comprehensive accounting of uncertainties and quantitative constraints on the PAR sources among biomass combustion, liquid fossil fuel combustion, and coal combustion at low and high temperatures. The results suggest that PAHs in this central European region had a clear predominance of coal combustion sources (75 +/- 6%; uncertainties represent 1 SD), mainly coal pyrolysis at low temperature (similar to 650 degrees C; 61 +/- 8%). Combustion of liquid fossil fuels and biomass represented 16 +/- 3 and 9 + 3% of the total PAR burden (Sigma PAH(14)), respectively. Although some soils were located close to potential PAR point sources, the source distribution was within a narrow range throughout the region. These observation-based top-down constraints on sources of environmental PARS provide a reference for both improved bottom-up emission inventories and guidance for efforts to mitigate PAR emissions.
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| 2. |
- Budhavant, Krishnakant, et al.
(författare)
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Apportioned contributions of PM2.5 fine aerosol particles over the Maldives (northern Indian Ocean) from local sources vs long-range transport
- 2015
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 536, s. 72-78
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Tidskriftsartikel (refereegranskat)abstract
- Urban-like plumes of gases and particulate matter originating from the South Asian region are frequently observed over the Indian Ocean, especially during the dry winter period. However, in addition to the strong sources on main-land South Asia, there are also local Maldivian emissions. The local contributions to the load of fine particulate matter (PM2.5) in the Maldivian capital Male was assessed using the well-established Maldives Climate Observatory at Hanimaadhoo (MCOH) to represent local background, recording the long-range transported component for a full-year synoptic campaign at both sites in 2013. The year-round levels in both Male and MCOH are strongly influenced by the seasonality of the monsoon cycle, including precipitation patterns and air-mass transport pathways, with lower levels during the wet summer season. The annual-average PM2.5 levels in Male are higher (avg. 19 mu g/m(3)) than at MCOH (avg. 13 mu g/m(3)) with the difference being the largest during the summer, when local emissions play a larger role. The 24-hWorld Health Organization (WHO) PM2.5 health guideline was surpassed for the week-long collections in 71% of the cases in Male and in 74% of the cases for Hanimaadhoo. This study shows that in the dry/winter season 90 +/- 11% of PM2.5 levels in Male could be from long-range transport with only 8 +/- 11% from local emissions while in the wet/monsoon season the relative contributions are about equal. The concentrations of organic carbon (OC) and elemental carbon (EC) showed similar seasonal patterns as bulk mass PM2.5. The relative contribution of total carbonaceous matter to bulk mass PM2.5 was 17% in Male and 13% at MCOH, suggesting larger contributions from incomplete combustion practices in the Male local region.
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| 3. |
- Budhavant, Krishnakant, et al.
(författare)
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Radiocarbon-based source apportionment of elemental carbon aerosols at two South Asian receptor observatories over a full annual cycle
- 2015
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Ingår i: Environmental Research Letters. - : IOP Publishing. - 1748-9326. ; 10:6
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Tidskriftsartikel (refereegranskat)abstract
- Black carbon (BC) aerosols impact climate and air quality. Since BC from fossil versus biomass combustion have different optical properties and different abilities to penetrate the lungs, it is important to better understand their relative contributions in strongly affected regions such as South Asia. This study reports the first year-round C-14-based source apportionment of elemental carbon (EC), the mass-based correspondent to BC, using as regional receptor sites the international Maldives Climate Observatory in Hanimaadhoo (MCOH) and the mountaintop observatory of the Indian Institute of Tropical Meteorology in Sinhagad, India (SINH). For the highly-polluted winter season (December-March), the fractional contribution to EC from biomass burning (f(bio)) was 53 +/- 5% (n = 6) atMCOHand 56 +/- 3% at SINH (n = 5). The f(bio) for the non-winter remainder was 53 +/- 11% (n = 6) atMCOHand 48 +/- 8%(n = 7) at SINH. This observation-based constraint on near-equal contributions from biomass burning and fossil fuel combustion at both sites compare with predictions from eight technology-based emission inventory (EI) models for India of (f(bio)) EI spanning 55-88%, suggesting that most current EI for Indian BC systematically under predict the relative contribution of fossil fuel combustion. Acontinued iterative testing of bottom-up EI with top-down observational source constraints has the potential to lead to reduced uncertainties regarding EC sources and emissions to the benefit of both models of climate and air quality as well as guide efficient policies to mitigate emissions.
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| 4. |
- Chen, Bing, et al.
(författare)
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Source Forensics of Black Carbon Aerosols from China
- 2013
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 47:16, s. 9102-9108
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Tidskriftsartikel (refereegranskat)abstract
- The limited understanding of black carbon (BC) aerosol emissions from incomplete combustion causes a poorly constrained anthropogenic climate warming that globally may be second only to CO2 and regionally, such as over East Asia, the dominant driver of climate change. The relative contribution to atmospheric BC from fossil fuel versus biomass combustion is important to constrain as fossil BC is a stronger climate forcer. The source apportionment is the underpinning for targeted mitigation actions. However, technology-based bottom-up emission inventories are inconclusive, largely due to uncertain BC emission factors from small-scale/household combustion and open burning. We use top-down radiocarbon measurements of atmospheric BC from five sites including three city sites and two regional sites to determine that fossil fuel combustion produces 80 +/- 6% of the BC emitted from China. This source-diagnostic radiocarbon signal in the ambient aerosol over East Asia establishes a much larger role for fossil fuel combustion than suggested by all 15 BC emission inventory models, including one with monthly resolution. Our results suggest that current climate modeling should refine both BC emission strength and consider the stronger radiative absorption associated with fossil-fuel-derived BC. To mitigate near-term climate effects and improve air quality in East Asia, activities such as residential coal combustion and city traffic should be targeted.
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| 5. |
- Kirillova, Elena N., et al.
(författare)
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C-13- and C-14-based study of sources and atmospheric processing of water-soluble organic carbon (WSOC) in South Asian aerosols
- 2013
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Ingår i: Journal of Geophysical Research - Atmospheres. - : American Geophysical Union (AGU). - 2169-897X .- 2169-8996. ; 118:2, s. 614-626
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Tidskriftsartikel (refereegranskat)abstract
- Water-soluble organic carbon (WSOC) is typically a large component of carbonaceous aerosols with a high propensity for inducing cloud formation. The sources of WSOC, which may be both of primary and secondary origins, are in general poorly constrained. This study assesses the concentrations and dual-carbon isotope (14C and 13C) signatures of South Asian WSOC during a 15-month continuous campaign in 2008-2009. Total suspended particulate matter samples were collected at Sinhagad (SINH) India and at the Maldives Climate Observatory at Hanimaadhoo (MCOH). Monsoon-driven meteorology yields significant WSOC concentration differences between the dry winter season (0.94±0.43 μg m-3 MCOH and 3.6±2.3 μg m-3 SINH) and the summer monsoon season (0.10±0.04 μg m-3 MCOH and 0.35±0.21 μg m-3 SINH). Radiocarbon-based source apportionment of WSOC shows the dominance of biogenic/biomass combustion sources but also a substantial anthropogenic fossil-fuel contribution (17±4% MCOH and 23±4% SINH). Aerosols reaching MCOH after long-range over-ocean transport were enriched by 3-4‰ in δ13C-WSOC relative to SINH. This is consistent with particle-phase aging processes influencing the δ13C-WSOC signal in the South Asian regional receptor atmosphere.
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