| 1. |
- Molnár, Peter, 1967, et al.
(författare)
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Roadside measurements of fine and ultrafine particles at a major road north of Gothenburg
- 2002
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Ingår i: Atmospheric Environment. - 1352-2310 .- 1873-2844. ; 36:25, s. 4115-4123
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Tidskriftsartikel (refereegranskat)abstract
- Particle measurements were conducted at a road site 15 km north of the city of Gothenburg for 3 weeks in June 2000. The size distribution between 10 and 368 nm was measured continuously by using a differential mobility particle sizer (DMPS) system. PM2.5 was sampled on a daily basis with subsequent elemental analysis using EDXRF-spectroscopy. The road is a straight four-lane road with a speed limit of 90 kph. The road passing the site is flat with no elevations where the vehicles run on a steady workload and with constant speed. The traffic intensity is about 20,000 cars per workday and 13,000 vehicles per day during weekends. The diesel fuel used in Sweden is low in sulphur content (< 10 ppm) and therefore the diesel vehicles passing the site contribute less to particle emissions in comparison with other studies. A correlation between PM2.5 and accumulation mode particles (100-368 nm) was observed. However, no significant correlation was found between number concentrations of ultrafine particles (10-100 nm) and PM2.5 or the accumulation mode number concentration. The particle distribution between 10 and 368 nm showed great dependency on wind speed and wind direction, where the wind speed was the dominant factor for ultrafine (10-100nm) particle concentrations. The difference in traffic intensity between workday and weekend together with wind data made it possible to single out the traffic contribution to particle emissions and measure the size distribution. The results presented in combination with previous studies show that both PM2.5 and the mass of accumulation mode particles are bad estimates for ultrafine particles. (C) 2002 Elsevier Science Ltd. All rights reserved.
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| 2. |
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| 3. |
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| 4. |
- Eliasson, Ingegärd, 1961, et al.
(författare)
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Summer nocturnal ozone maxima in Goteborg, Sweden
- 2003
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Ingår i: ATMOSPHERIC ENVIRONMENT. - 1352-2310. ; 37:19, s. 2615-2627
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Tidskriftsartikel (refereegranskat)abstract
- The magnitude and frequency of nocturnal ozone maxima in a high mid-latitude city (Göteborg, Sweden) has been analysed. Nocturnal ozone maxima have been reported from cities in Europe and North America and can be explained by vertical mixing of high ozone concentrations from higher levels or horizontal transportation from rural areas through local and mesoscale wind systems. Data from four summer months (May–August) in 1994 were used to analyse the relative importance of local- and mesoscale wind systems and vertical mixing in Göteborg during clear and calm weather conditions. Results show that nocturnal ozone maxima frequently occur during these conditions, with a magnitude up to 104 μg m−3. The nocturnal ozone maxima were positively correlated to both situations with a well-developed land breeze and situations with vertical mixing. During the period investigated, in total 17 nights with secondary ozone maximum occurred. The majority of the secondary ozone maxima (80%) appeared early in the night, i.e. an ozone increase within the first 3 h after sunset and sometimes even two peaks occurred. Seven of these occasions can be explained by horizontal advection, eight by vertical mixing and five cannot by certainty be explained to be due to horizontal or vertical transportation only. During the measurement period the Swedish guideline of 80 μg m−3 (for 1-h value) was exceeded 55% of the days (i.e. 68 days, 557 h) and 33% of the nights (i.e. 41 nights, 103 h) in the central parts of Göteborg. The results thus show that in Scandinavia nocturnal ozone
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| 5. |
- Gårdfeldt, Katarina, 1959, et al.
(författare)
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Evasion of Mercury from coastal and open waters of the Atlantic ocean and the Mediterranean sea
- 2003
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Ingår i: Atmospheric Environment. - 1352-2310 .- 1873-2844. ; 37:Suppl 1, s. S73-S84
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Tidskriftsartikel (refereegranskat)abstract
- Dissolved gaseous mercury (DGM) was measured in coastal Atlantic seawater and in the Mediterranean Sea. The Atlantic measurements were performed during September 1999 at the Mace Head Atmospheric Research Station, situated on the Irish west coast. The measurements in the Mediterranean Sea were made along a 6000 km cruise path from 14 July to 9 August 2000 in the framework of the Med-Oceanor project. Total gaseous mercury (TGM) concentrations in air were continuously measured with a 5 min time resolution using an automated mercury analyser (Tekran 2537A) during both expeditions. Paired TGM and DGM samples from all campaigns showed that the surface water was supersaturated with elemental mercury. The mercury evasion was estimated using a gas exchange model (J. Geophys. Res. 97 (1992) 7373), which uses salinity, wind speed and water temperature as independent parameters. The predicted average mercury evasion from the coastal Atlantic water was 2.7 ng m−2 h−1 implying that the concentration of TGM in the Atlantic air is enhanced by mercury evasion from the sea. Measurements in different regions of the Mediterranean Sea showed spatial variations in DGM concentrations. The highest DGM concentration (90 pg l−1) was observed at a location in the Strait of Sicily (37°16N 11°52E). The mercury evasion in the eastern sector of the Mediterranean Sea (area: 32–36°N, 17–28°E) was generally higher (7.9 ng m−2 h−1) than that observed in the Tyrrhenian Sea (4.2 ng m−2 h−1) or in the western sector (2.5 ng m−2 h−1) (areas: 38–42°N, 8–13°E and 38–41°N, 7–8°E, respectively). Estimations of mercury evasion were also made at Mediterranean coastal sites using a dynamic chamber technique. In addition, a newly developed method making continuous in situ DGM measurements possible was tested.
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| 6. |
- Gårdfeldt, Katarina, 1959, et al.
(författare)
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Oxidation of atomic mercury by hydroxyl radicals and photoinduced decomposition of methylmercury species in the aqueous phase
- 2001
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Ingår i: Atmospheric Environment. - 1352-2310 .- 1873-2844. ; 35:17, s. 3039-3047
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Tidskriftsartikel (refereegranskat)abstract
- The rate constant for Hg0+.OH, kHg0+.OH=(2.4±0.3)×109 M−1 s−1, in the aqueous phase was determined using a relative rate technique with methyl mercury as reference compound. The .OH initiated mercury reaction proceeds via the molecular Hg(I) radical which is oxidised to Hg(II) by dissolved O2. The reaction can be of importance under certain atmospheric circumstances, such as when the aqueous phase capacity of forming OH radicals is significant and the gas phase concentration of ozone drops. The same end product, i.e. Hg(II) was observed from the photodegradation of methylmercury hydroxide. In this case, molecular Hg(I) radicals are again likely to be formed after photodegradation of the Hg–C bond with subsequent oxidation. A lifetime of 230 h of methylmercury at outdoor conditions was estimated due to this reaction. The action of .OH on methylmercury species also involves breaking of organometallic bonds and formation of Hg(II). Speciation of these reaction products from methylmercury is important for the estimation of biogeochemical cycling of mercury.
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| 7. |
- 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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| 8. |
- Janhäll, Sara, 1965, et al.
(författare)
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Vertical distribution of air pollutants at the Gustavii Cathedral in Goteborg, Sweden
- 2003
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Ingår i: Atmospheric Environment. - 1352-2310. ; 37:2, s. 209-217
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Tidskriftsartikel (refereegranskat)abstract
- Atmospheric trace gases and particles were measured at two heights at the Gustavii Cathedral in Goteborg, Sweden, during 7 weeks in September and October 1999. The Gustavii Cathedral is situated in the city centre of Goteborg, which is near the harbour area and encircled by heavy traffic some hundred metres away. The main body of the church is as high as the surrounding buildings, while the tower extends well above. The sampling points were placed on the west wall of the tower at 10 and 32 m height, i.e. well below and above the roof top level of surrounding buildings, respectively. Sulphur dioxide and nitric acid were sampled using the denuder technique and analysed by Ion Chromatography, IC. Total suspended particulates (TSP) were sampled using filter cups and subsequently analysed by energy dispersive X-ray fluorescence spectroscopy (EDXRF). In addition to the diurnal sampling of species, nitrogen oxides were measured using chemiluminescence detectors. Additional data from the Environmental Office in Goteborg was used in the analysis. Differences between the concentrations measured at the upper and lower levels were calculated and their variation and dependence on meteorological factors were evaluated. On the average larger concentrations were found at the lower level for soil derived elements and TSP, while nitric acid and nitric oxide showed larger concentrations at the upper level. Sulphur dioxide and nitrogen dioxide, as well as many of the elements in the TSP, showed equal concentrations at the two levels. However, depending on wind direction the measured differences of nitrogen oxides could be both positive and negative. (C) 2002 Elsevier Science Ltd. All rights reserved.
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| 9. |
- Jonsson, Per, 1974, et al.
(författare)
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Suspended particulate matter and its relations to the urban climate in Dar es Salaam, Tanzania
- 2004
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 38:25, s. 4175-4181
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Tidskriftsartikel (refereegranskat)abstract
- Relationships between sources and levels of particulate matter and climatic parameters (urban heat island intensity, wind speed, temperature and relative humidity) were investigated in the coastal city of Dar es Salaam, Tanzania's largest city. Measurements were made during the wet and dry seasons of 2001 at an urban and a rural site. Five elements were used to represent different sources: K in fine particles (biomass), Zn in fine particles (industry), Cl in coarse particles (sea spray), Ti in coarse particles (soil) and Pb in fine particles (traffic). The concentrations of these elements varied considerably between the urban and rural site during both the wet and dry season, with the urban site in the dry season having the highest concentrations. Diurnal differences are also apparent, although not as straightforward. In an attempt to explain these differences, correlations between all elements and the climatic parameters were investigated. The results show that the nocturnal urban heat island intensity was positively correlated and wind speed negatively correlated with particulate levels, presumably due to the increased atmospheric stability. (C) 2004 Elsevier Ltd. All rights reserved.
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| 10. |
- Karlsson, G. P., et al.
(författare)
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Test of the short-term critical levels for acute ozone injury on plants - improvements by ozone uptake modelling and the use of an effect threshold
- 2004
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 38:15, s. 2237-2245
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Tidskriftsartikel (refereegranskat)abstract
- The current short-term critical levels for acute ozone injury on plants were evaluated based on 32 datasets from eastern Austria, Belgium and southern Sweden with subterranean clover (Trifolium subterraneum L., cv. Geraldton). Potential improvements using an exposure index related to ozone uptake (AF(st), Accumulated Stomatal Flux), a modified accumulated exposure over the threshold (mAOT) exposure index and the introduction of an effect threshold in the short-term critical level were investigated. The existing short-term critical levels did not accurately describe the effects in terms of observed visible injury. Using a mAOT based on solar radiation and vapour pressure deficit (VPD) improved the explanation of observed visible injury. However, using a simple stomatal conductance model, driven by solar radiation, air temperature, VPD and ozone uptake, the correlation between modelled and observed effects were considerably improved. The best performance was obtained when an ozone uptake rate threshold of 10 nmol m(-2) s(-1) (AF(st)10, per unit total leaf area) was used. The results suggested the use of an effect threshold of 10% leaf injury in order to minimise the risk of erroneously recorded visible injury due to observation technique or other injuries hard to distinguish from ozone injury. A new, AF(st) based exposure index was suggested, an ozone exposure of AF(st)10=75 mumol m(-2) during an exposure period of eight days was estimated to prevent more than 10% visible injury of the leaves. This study strongly suggests that a simple model for ozone uptake much better explains observed effects, compared to the currently used exposure index AOT40. However, if a lower degree of complexity, data requirements and also a lower extent of explanation of observed effects are to be considered a new short-term critical level, based on a mAOT may be suggested: a mAOT30 of 160 ppb h during an exposure period of 8 days is estimated to protect the leaves from visible injury on more than 10% of the leaves. (C) 2004 Elsevier Ltd. All rights reserved.
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