| 1. |
- 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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| 4. |
- 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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| 5. |
- 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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| 6. |
- Fick, Jerker, et al.
(författare)
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Formation of oxidation products in a ventilation system
- 2004
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 38:35, s. 5895-9
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the formation of oxidation products from the ozonolysis of a monoterpene (α-pinene) in an authentic ventilation system. We observed ten products, norpinic acid, pinic acid, glyoxal, methyl glyoxal, norpinonic acid, pinonic acid, a C4 dicarbonyl (C4H6O2), a C5 dicarbonyl (C5H8O2), norpinon aldehyde, and pinon aldehyde. Experiments were conducted at a low (2.0 g m−3) and moderate (8 g m−3) humidity levels. All products but C4 dicarbonyl and norpinon aldehyde were detected at the low humidity level, but only glyoxal, methyl glyoxal, C4 dicarbonyl, norpinon aldehyde and pinon aldehyde were detected at a moderate humidity. Experiments were conducted at low ppb levels (75 ppb ozone and 4 and 10 ppb α-pinene) and with a short reaction time (75 s). Experiments showed that 5–6% of the α-pinene reacted, which was approximately 4–5 times more than predicted by theoretical calculations. This discrepancy suggests a significant contribution from heterogeneous reactions. These oxidation products were formed despite low reactant concentrations and a short reaction time, indicating that the formation of oxidation products likely occurs at ambient levels and in real settings.
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| 7. |
- Gidhagen, Lars, et al.
(författare)
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Simulation of NOx and ultrafine particles in a street canyon in Stockholm, Sweden
- 2004
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 38:14
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Tidskriftsartikel (refereegranskat)abstract
- A computational fluid dynamic (CFD) model has been used to assess the concentrations of NOx and particle number in a street canyon in Stockholm with a high traffic volume. Comparisons of a simulated 11-week long time series of NOx with measurements (both sides of the street, urban background excluded) show good agreement, especially if emissions are distributed to be three times higher along the side of the street where the traffic is uphill, as compared to the downhill side. The simulation of number concentrations of inert particles indicates a similar asymmetry in emissions. A month-long measurement of particle size distribution (7–450 nm) at street level indicates that the ratio of nucleation size mode particle (7–20 nm) to total particle number (7–450 nm) is decreasing for increased particle surface area. Given the strong dominance of the locally generated particles over the urban background, this is interpreted as a local change in the size distribution. The results of a monodisperse aerosol dynamic model, coupled to the CFD model that simulates also the turbulence generated by vehicle movements, show that coagulation and deposition may reduce total particle inside the canyon with approximately 30% during low wind speeds. Most of the removal occurs shortly after emission, before the particles reach the leeward curb-side. Losses between the leeward curb-side and other locations in the street, e.g. roof levels, is estimated to be smaller, less than 10%. Coagulation is the dominating removal process under low wind speed conditions and deposition for higher wind speeds, the summed removal being smaller for high wind velocities. Deposition is enhanced over the road surface due to the velocities generated by vehicle movements. Although coagulation and deposition removal is most effective on the smallest ultrafine particles, this effect is not sufficient to explain the observed change in size distribution. It is suggested that also the formation of particles in the exhaust plumes is influenced by a larger particle surface area in the ambient air.
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| 8. |
- Hazenkamp-Von Arx, M.E., et al.
(författare)
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PM2.5 and NO2 assessment in 21 European study centres of ECRHS II : annual means and seasonal differences
- 2004
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Ingår i: Atmospheric Environment. - : Elsevier. - 1352-2310 .- 1873-2844. ; 38:13, s. 1943-1953
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Tidskriftsartikel (refereegranskat)abstract
- The follow-up of cohorts of adults from more than 20 European centres of the former ECRHS I (1989-1992) investigates long-term effects of exposure to ambient air pollution on respiratory health, in particular asthma and change of pulmonary function. Since PM2.5 is not routinely monitored in Europe, we measured PM2.5 concentrations in 21 participating centres to estimate 'background' exposure in these cities. Winter (November-February), summer (May-August) and annual mean (all months) values of PM2.5 were determined from measuring periods between June 2000 and November 2001. Sampling was conducted for 7 days per month for a year. Annual and winter mean concentrations of PM2.5 vary substantially being lowest in Iceland and highest in centres in Northern Italy. Annual mean concentrations ranged from 3.7 to 44.9 mug m(-3), winter mean concentrations from 4.8 to 69.2 mug m(-3), and summer mean concentrations from 3.3 to 23.1 mugm(-3). Seasonal variability occurred but did not follow the same pattern across all centres. Therefore, ranking of centres varied from summer to winter. Simultaneously, NO2 concentrations were measured using passive sampling tubes. Annual mean NO2 concentrations range from 4.9 to 72.1 mug m(-3) with similar seasonal variations across centres and constant ranking of centres between seasons. The correlation between annual NO2 and PM2.5 concentrations is fair (Spearman correlation coefficient r(s) = 0.75), but when considered as monthly means the correlation is far less consistent and varies substantially between centres. The range of PM2.5 mass concentrations obtained in ECRHS II is larger than in other current cohort studies on long-term effects of air pollution. This substantial variation in PM2.5 exposure will improve statistical power in future multilevel health analyses and to some degree may compensate for the lack of information on within-city variability. Seasonal means may be used to indicate potential differences in the toxicity across the year. Across ECRHS cities annual NO2 might serve as a surrogate for PM2.5, especially for past exposure assessment, when PM2.5 is not available.
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| 9. |
- Janhäll, Sara, 1965, et al.
(författare)
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Size resolved traffic emission factors of submicrometer particles
- 2004
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 38:26, s. 4331-4340
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Tidskriftsartikel (refereegranskat)abstract
- Size resolved emission factors for submicrometer particles related to trace gases have been obtained from measurement data at a suburban road side, with a traffic intensity of 18,000 vehicles per day. Number of particles with diameter 10-368 nm, trace gases (NO, NOx, O-3 and SO2) traffic and meteorology parameters were measured outside of Goteborg, Sweden. Size distributions of small particles at the site are presented and their relation to meteorological and traffic related variables was evaluated. Wind speed correlated negatively with 10-368 nm particles and temperature correlated negatively with the smaller particles (10-60 nm). Nitric oxide was shown to be a better tracer for traffic related ultrafine particles, than traffic intensity itself. The calculated emission factor, with errors at 95% confidence level, for particles in the range 10-368 nm is presented in relation to nitrogen oxides. The emission factors were 268+/-60 and 176+/-37 particles cm(-3) per ppb NO and NOx, respectively. The particle emission factors for 10-100, 10-50, 50-170 and 170-368 nm were 260+/-70, 228+/-52, 41+/-11 and <1 particle cm(-3) per ppb NO, respectively. The size distribution of the emissions is given by number of particles normalised by the width of the size bin, i.e. in units of dNd log Dp(-1) ppb(-1). The maximum normalised emission factor was 450 cm(-3) per ppb NO for 20 nm particles. The shape of the size distribution of emissions revealed one sharp peak at 20 nm, with a small shoulder at 70 nm. (C) 2004 Elsevier Ltd. All rights reserved.
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