| 1. |
- Agrell, Cecilia, et al.
(författare)
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PCB congeners in precipitation, wash out ratios and depositional fluxes within the Baltic Sea region, Europe
- 2002
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Ingår i: Atmospheric Environment. - 1352-2310. ; 36:2, s. 371-383
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Tidskriftsartikel (refereegranskat)abstract
- Concentrations of PCB congeners were determined in precipitation and the annual and seasonal depositional fluxes were calculated for 16 (mostly rural) stations around the Baltic Sea during 1990-1993. The concentrations of individual congeners in precipitation were found to be influenced by atmospheric concentrations of PCBs, ambient temperature, precipitation volume and physico-chemical properties of the compounds. Median levels of PCBs in precipitation differed one order of magnitude between stations. When analyzing all data together to obtain regional trends, concentrations of PCBs in precipitation decreased with increasing temperature. This relationship was the same for all stations but differed in the magnitude of the slope for individual congeners. Low chlorinated PCB congeners showed steeper slopes for the temperature relationship than did high chlorinated congeners, a result explained by high atmospheric concentrations of the low chlorinated congeners during low temperatures. Annual wash out ratios were between 31 and 72 x 103 and tended to be higher for the high chlorinated congeners. Wash out ratios decreased with increasing temperature for all congeners except PCB-33. At snow scavenging events, the wash out ratio of PCBs increased with a factor of 2. Latitudinal trends for PCB concentrations in precipitation and deposition were generally not statistically significant. The calculated yearly deposition of PCBs to the Baltic Sea was 390 and 5-18 kg for individual congeners, with PCB-138 having the highest flux. Deposition of PCB congeners varied seasonally, with a factor between 2 and 3, and was generally highest during fall. Relatively higher deposition of low chlorinated congeners compared to high chlorinated congeners was found during winter. (C) 2002 Elsevier Science Ltd. All rights reserved.
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| 2. |
- Backe, Cecilia, et al.
(författare)
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Polychlorinated biphenyls in the air of southern Sweden - spatial and temporal variation
- 2000
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Ingår i: Atmospheric Environment. - 1352-2310. ; 34:9, s. 1481-1486
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Tidskriftsartikel (refereegranskat)abstract
- Polychlorinated biphenyls in the lower atmosphere were studied over a regional area covering approximately 11000 km(2) in southern Sweden. Sampling were performed in 1992-1993, continuously during one year, where samples from 11 sampling-sites (in all 260 samples) were analysed. PCB concentrations ranged over two order of magnitudes, 7-983 pg m(-3). Differences in PCB concentrations among the sampling sites revealed a large number of high-concentration outliers, mainly originating from one suburban site. Smaller differences in PCB concentrations between sites probably originated from varying geographical and meteorological conditions, that affected exchange processes between air and surfaces differently at the sampling sites. (C) 2000 Elsevier Science Ltd. All rights reserved.
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| 3. |
- Gidhagen, L, et al.
(författare)
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Model simulation of ultrafine particles inside a road tunnel
- 2003
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Ingår i: Atmospheric Environment. - 1352-2310. ; 37:15, s. 2023-2036
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Tidskriftsartikel (refereegranskat)abstract
- A monodispersive aerosol dynamic model, coupled to a 3D hydrodynamical grid model, has been used to study the dynamics of ultrafine particles inside a road tunnel in Stockholm, Sweden. The model results were compared to measured data of particle number concentrations, traffic intensity and tunnel ventilation rate. Coagulation and depositional losses to the tunnel walls were shown to be important processes during traffic peak hours, together contributing to losses of 77% of the particles smaller than 10nm and 41% of the particles of size 10-29nm. Particle growth due to water uptake or the presence of a micron-sized, resuspended particle fraction did not have any significant effect on the number of particles lost due to coagulation. Model simulation of particle number concentration response to temporal variations in traffic flow showed that constant emission factors could be used to reproduce the concentration variations of the particles larger than 29nm, while vehicle-speed-dependent factors are suggested to reproduce the variation of the smallest fractions. The emission factors for particle number concentrations estimated from the model simulation are in general higher and show a larger contribution from light-duty vehicles than what has been reported from a tunnel in California. The model study shows that combined measurements and model simulations in road tunnels can be used to improve the determinations of vehicle emission factors for ultrafine particles under realistic driving conditions. (C) 2003 Elsevier Science Ltd. All rights reserved.
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| 4. |
- Hedberg, E, et al.
(författare)
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Chemical and physical characterization of emissions from birch wood combustion in a wood stove
- 2002
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Ingår i: Atmospheric Environment. - 1352-2310. ; 36:30, s. 4823-4837
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to characterize the emissions of a large number of chemical compounds emitted from birch wood combustion in a wood stove. Birch wood is widely used as fuel in Swedish household appliances. The fuel load was held constant during six experiments. Particles < 2.5 mum diameter were collected and the size distribution of the particles was measured. The results were compared to the size distribution in road traffic emissions. It could be seen that the number distribution differed between the sources. In traffic exhaust, the number of particles maximized at 20 nm, while the number distribution from wood burning ranged from 20 to 300 nm. The ratio K/Ca on particles was found. to be significantly different in wood burning compared to road dust, range 30-330 for the former and 0.8+/-0.15 for the latter. The source profile of common elements emitted from wood-burning differed from that found on particles at a street-level site or in long-distance transported particles. The ratio toluene/benzene in this study was found to be in the range 0.2-0.7, which is much lower than the ratio 3.6+/-0.5 in traffic exhaust emissions. Formaldehyde and acetone were the most abundant compounds among the volatile ketones and aldehydes. The emission factor varied between 180-710mg/kg wood for formaldehyde and 5-1300mg/kg wood for acetone. Of the organic acids analyzed (3,4,5)-trimethoxy benzoic acid was the most abundant compound. Of the PAHs reported, fluorene, phenanthrene, anthracene, fluoranthene and pyrene contribute to more than 70% of the mass of PAH. Of the elements analyzed, K and Si were the most abundant elements, having emission factors of 27 and 9mg/kg wood, respectively. Although fluoranthene has a toxic equivalence factor of 5% of benzo(a)pyrene (B(a)P), it can be seen that the toxic potency of fluoranthene in wood burning emissions is of the same size as B(a)P. This indicates that the relative carcinogenic potency contribution of fluoranthene in wood smoke would be about 40% of B(a)P. (C) 2002 Elsevier Science Ltd. All rights reserved.
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| 5. |
- Ketzel, M, et al.
(författare)
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Particle and trace gas emission factors under urban driving conditions in Copenhagen based on street and roof-level observations
- 2003
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Ingår i: Atmospheric Environment. - 1352-2310. ; 37:20, s. 2735-2749
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Tidskriftsartikel (refereegranskat)abstract
- Simultaneous measurements of particle size distribution (size/range 10-700 nm) inside an urban street canyon and a nearby urban background location in Copenhagen in May-November 2001 were used to separate the traffic source contribution in the street canyon from the background levels. The background concentrations are highly variable due to changing contributions from long-range transport and local sources showing a diurnal pattern with a shift to smaller particle sizes during midday hours. The average ratio background/street concentration is 0.26 for NOx and 0.35, 0.42, 0.60, 0.64, respectively, for CO, total particle number (ToN), surface and volume. The particle size distribution of the traffic source shows during daytime and evening hours (6-24) a maximum at particle sizes of 20-30 nm independent of the changing heavy-duty vehicle share during the same time interval. The particle number concentration highly correlated (R > 0.83) with NOx through a wide range of particle sizes. The method of inverse modelling was applied to estimate average fleet emission factors typical of urban conditions in Denmark. Emission factors per average vehicle were estimated as (2.8 +/- 0.5) x 10(14) particles/km, (1.3 +/- 0.2) g NOx/(veh km) and (11 +/- 2) g CO/(veh km). We observe two types of 'nanoparticle events' (a) in background, probably due to photochemistry and (b) in the night hours when traffic is dominated by diesel taxis. During night hours (0-5), the maximum in the emitted particle size distribution, is shifted to smaller sizes of about 15-18 nm. This shift to smaller particle sizes is related to an increase in the average NOx and ToN emission per vehicle by a factor of 2-3 and a reduced CO emission also by a factor of 2-3. (C) 2003 Elsevier Science Ltd. All rights reserved.
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| 6. |
- ter Schure, Arnout, et al.
(författare)
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Polybrominated diphenyl ethers in precipitation in Southern Sweden (Skane, Lund)
- 2002
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Ingår i: Atmospheric Environment. - 1352-2310. ; 36:25, s. 4015-4022
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Tidskriftsartikel (refereegranskat)abstract
- The presence of polybrominated diphenyl ether (PBDE) flame retardants in total deposition (wet + dry) was assessed with the simultaneous use of three bulk samplers during a 2 week period. The particle associated and the 'dissolved' phase were separated during sampling. Volume weighted mean (VWM) concentrations of SigmaPBDE (9 congeners) in rain were 209 pg l(-1). Total deposition rates were 2 +/- 1 ng SigmaPBDE m(-2) day(-1). The total PBDE deposition was dominated by decaBDE(209) and thereafter 2,2'4,4'-tetraBDE(47) and 2,2'4,4',5-pentaBDE(99). Concentrations of particle associated and 'dissolved' PBDEs in total deposition were used to calculate filter/adsorbent ratios (F/A). We found that 65 +/- 18% of the total PBDEs were particle associated. Low F/A ratios for higher brominated congeners (Br > 5) were observed. This is contradictory with predictions based on the PBDEs' physico-chemical properties and was attributed to sampling artefacts, such as particle size distribution, and/or non-equilibrium processes. There was a negative relationship between the particulate SigmaPBDE concentration and rain volume suggesting a dilution effect and the importance of particle scavenging for wet deposition of PBDEs. (C) 2002 Elsevier Science Ltd. All rights reserved.
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| 7. |
- Agrell, Cecilia, et al.
(författare)
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Polybrominated diphenyl ethers (PBDES) at a solid waste incineration plant I: Atmospheric concentrations
- 2004
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 38:30, s. 5139-5148
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Tidskriftsartikel (refereegranskat)abstract
- In the first of two papers, the atmospheric poly brominated diphenyl ether (PBDE) concentrations at a municipal solid waste incineration (MSW) plant with electronic recycling is compared with that at an industrial urban reference site producing asphalt and concrete. In the second paper, atmospheric deposition and washout behaviour is presented (Atmos. Environ. (2004a)). PBDEs (BDE28, -47, -66, -100, -154, -153, -183, -209) in the gaseous and particulate phase were measured with high resolution in time during the colder parts of the year to minimise the influence of potential historical pollution at the sites through volatilisation. This also means that reported levels are lower compared to other reported data. Results of BDE47 (TetraBDE) and BDE209 (DecaBDE) as representatives of "old" vs. "new" PBDEs as well as SigmaPBDE, excluding BDE209, are presented. Median SigmaPBDE, BDE47 and BDE209 concentration were 6.3, 2.1 and 10.4 pg m(-3) at the MSW and 3.5, 1.7 and 6.5 pg m-3 at the reference site. The total concentrations (gaseous and particulate phase) were significantly higher at the MSW compared to the reference site for SigmaPBDE and BDE47 but not for BDE209. The same results were obtained regarding concentrations in the gaseous phase. Particle concentrations were significantly higher at the MSW for SigmaPBDE, BDE47 and BDE209. Within each site, the gaseous-phase concentration was significantly higher than the particulate-phase concentration except for BDE209 at the MSW. Thus, the proportion of BDE209 detected in the particulate phase was higher at the MSW compared to the reference site. Together with the results of the second paper, we suggest that treatment of waste is presently a source of "old" PBDEs to the environment, whereas the rather similar BDE209 concentrations at the two sites are more a result of proximity to potential diffuse sources.
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| 8. |
- Bengtsson, Göran, et al.
(författare)
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Persistence of plasmid RP4 in Pseudomonas putida and loss of its expression of antibiotic resistance in a groundwater microcosm
- 2004
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 36:6, s. 999-1008
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Tidskriftsartikel (refereegranskat)abstract
- We examined the stability of plasmid RN and its expression of antibiotic-resistance genes in suspended and sorbed Pseudomonas putida in aquifer microcosms. Test tubes containing different proportions of sterilized aquifer soil and groundwater were inoculated with bacteria and incubated for up to 26 d. Serial dilutions were made to agar plates with or without antibiotics, to quantify the functional stability of the plasmid. The structural integrity of RN was examined by plasmid extraction, digestion with restriction enzymes, and agarose gel electrophoresis. The plasmid-borne resistance gene expression disappeared in 80-90% of the cells during day 1 of incubation in aquifer soil and then remained at that frequency throughout the experiment. The RP4 plasmid was present in cells without antibiotic-resistance gene expression, indicating that the observed loss of plasmid-encoded activity was most likely due to a reduction in expression of the resistance genes. The increased growth rate in groundwater amended with glucose and phosphate had no significant influence on plasmid loss or antibiotic-resistance expression, suggesting that plasmid loss and antibiotic-resistance expression were independent of the growth rate. Most of the reduction of resistance gene expression was associated with the presence of soil particles, and 70% of the resistance expression was retained in bacteria incubated for 1 d in groundwater alone. Bacteria sorbed to the soil particles had a lower frequency of expression of resistance genes than suspended bacteria, but the difference was not caused by sorbed inorganic or organic chemicals. Resistance gene expression was partly recovered in suspended bacteria after in vitro exposure to the antibiotics and after first isolating on agar without antibiotics and then replica plating to agar containing the antibiotics.
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| 9. |
- Bidleman, TF, et al.
(författare)
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Chiral signatures of chlordanes indicate changing sources to the atmosphere over the past 30 years
- 2004
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 38:35, s. 5963-5970
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Tidskriftsartikel (refereegranskat)abstract
- Chlordane was used as an insecticide for half a century until its withdrawal from the world market in 1997. Trans- and cis-chlordane (TC, CC) are racemic in the technical product, but undergo enantio selective degradation in soil to leave nonracemic residues. In most cases, the (+) enantiomer of TC and the (-) enantiomer of CC are depleted, leading to enantiomer fractions, EF = (+)/[(+) + (-)], that are < 0.500 for TC and > 0.500 for CC. Nonracemic EFs of TC and CC, showing the same degradation preference as soils, were found in 1998-2001 air samples from stations in Arctic Canada and Finland, and on the west coast of Sweden. Environmental samples representing different time periods of chlordane history were also examined in: (a) archived atmospheric deposition samples collected in Sweden, Slovakia and Iceland in 1971-1973, (b) soils from southern Sweden sampled in 2001 and (c) a laminated lake sediment core from the Canadian Arctic representing similar to50 years of accumulation. TC and CC were racemic or nearly so in the historical atmospheric deposition samples and nonracemic in the Swedish soils. The EF of TC in the dated take sediment core decreased from nearly racemic in the past to nonracemic in recent times. These observations suggest that sources of chlordane to the atmosphere have changed over time and are now influenced to a greater extent by emission from soils.
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| 10. |
- Ketzel, M, et al.
(författare)
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Modelling the fate of ultrafine particles from exhaust pipe to rural background: an analysis of time scales for dilution, coagulation and deposition
- 2004
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 38:17, s. 2639-2652
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the time scales of various dynamic processes during the evolution of the particle size distribution from its emission from a vehicle exhaust pipe through its dilution at kerbside and urban level. In addition, the situation in a road tunnel or near a highway is discussed. The derived formula framework allows the estimation of approximated time scales based on a given particle size distribution for the processes dilution with background air, coagulation, deposition and condensation. The variation of the time scales for these processes with "lifetime" of the exhaust particles and the dependence of the time scales on the particle size is shown. We identify the spatial or temporal scales under which the discussed processes are important and have to be included in operational particle pollution models. (C) 2004 Elsevier Ltd. All rights reserved.
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