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| 2. |
- Sundin, Eva, et al.
(författare)
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Energy budget approach to urban snow deposit melt
- 1999
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Ingår i: Nordic Hydrology. - : IWA Publishing. - 0029-1277 .- 1996-9694. ; 30:1, s. 39-56
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Tidskriftsartikel (refereegranskat)abstract
- In urban areas in cold regions snow handling is a significant part of municipal activity. The snow is usually ploughed off the streets and then transported to a snow deposit. As a consequence the snow is mechanically blended, packed, polluted and piled up, giving it a characteristic texture, shape, and size. To predict snow deposit melt an energy budget model that uses general meteorological data has been derived. The model is a synthesis of available energy balance terms developed for natural snow covers, and general mass and heat transfer considerations. This approach was found applicable for estimating snow deposit melt. Only geometry, radiation, sensible and latent heat are included to the model. Radiation was found to be the major source of snow deposit melt. Very little difference was found between top and side energy fluxes. Model predictions were compared with measurements of two pilot snow deposits which were constructed with snow collected from the streets of Lulea, Sweden. The degree day approach also seems to be an applicable method to estimate snow deposit melt
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| 3. |
- Viklander, Maria
(författare)
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Dissolved and particle-bound substances in urban snow
- 1999
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 39:12, s. 27-32
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Tidskriftsartikel (refereegranskat)abstract
- In order to create a picture of the pollutant pathways for snow in urban areas, snow samples were collected in the city of Lulea, northern Sweden. Sampling sites were chosen in the city centre and in a housing area three different sites in each area. Snow samples were collected during the whole winter of 1995. The results showed that the amounts of dissolved substances as percentages of the total amounts varied according to time, site and the type of substance. For the sites along the roadsides in the city centre, the amounts that were in solution were less than 1% of the lead, 2.5% of the phosphorus, 11% of the copper, and 18% of the zinc. For the site with no-traffic, the dissolved fractions were considerably higher.In order to create a picture of the pollutant pathways for snow in urban areas, snow samples were collected in the city of Lulea northern Sweden. Sampling sites were chosen in the city centre and in a housing area - three different sites in each area. Snow samples were collected during the whole winter of 1995. The results showed that the amounts of dissolved substances as percentages of the total amounts varied according to time, site and the type of substance. For the sites along the roadsides in the city centre, the amounts that were in solution were less than 1% of the lead, 2.5% of the phosphorus, 11% of the copper, and 18% of the zinc. For the site with no-traffic, the dissolved fractions were considerably higher
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| 4. |
- Viklander, Maria
(författare)
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Particle size distribution and metal content in street sediments
- 1998
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Ingår i: Journal of environmental engineering. - 0733-9372 .- 1943-7870. ; 124:8, s. 761-766
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Tidskriftsartikel (refereegranskat)abstract
- Sediments that had accumulated during the winter season, and which were left at the surface when the snow had melted, were studied with regard to physical and chemical characteristics. The investigation was carried out in the city of Luleå, which is located in northern Sweden. Sediment samples were collected in the city center and in a housing area at streets with different traffic loads. The results showed that the amount of the sediments at a street surface was evidently affected by the presence of a sidewalk. The street with a sidewalk accumulated much more sediment than the street without a sidewalk did. Both of these streets had approximately the same traffic load. The sidewalk also affected the particle size distribution. The content of heavy metals in the sediments varied with the traffic load and the area type. The highest concentration of cadmium, lead, and zinc was found in the street with the highest traffic load.
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| 5. |
- Viklander, Maria
(författare)
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Snow quality in the city of Lulea, Sweden : time-variation of lead, zinc, copper and phosphorus
- 1998
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Ingår i: Science of the Total Environment. - 0048-9697 .- 1879-1026. ; 216:1-2, s. 103-112
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Tidskriftsartikel (refereegranskat)abstract
- The quality of urban snow was studied with regard to how the concentrations of selected metals and phosphorus vary over time. The area studied is situated in northern Sweden (65°36 prime N; 22°13 prime E). Snow samples were taken at three different locations in the city centre, approximately every second week, throughout winter. This study has clearly shown the importance of local conditions and snow clearance operations on snow quality. The study also shows that it is difficult to interpret and predict the concentrations of lead, zinc, copper and phosphorus in the snow. However, it should be possible to predict the mass loads of these substances from the deposition velocities, if the snow handling methods and routines, as well as the local circumstances are known.
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| 6. |
- Viklander, Maria
(författare)
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Snow quality in urban areas
- 1997
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The studies reported on this thesis aim to provide information and increase knowledge about the quality of urban snow and the path of pollutants. The results develop a basis for decisions regarding the prevention of environmental damage. A number of projects have been carried out to provide more detailed knowledge about: snow quality in cities, sediments that had accumulated during the winter, and that were left at the surface when the snow had melted, and the paths of pollutants at urban snow deposit. For these purposes studies have been performed in laboratory, pilot and full scale. The snow quality was studied in the city of Luleå with regard to variation with time and area. The aim was to investigate urban snow in its actual environment, throughout an entire winter season. Snow samples were taken in a housing area and in the city centre, at sites with different traffic load. It was found that traffic or activities related to traffic was a major source of heavy metals and phosphorus in urban snow, both in the city centre and the housing area. Also the type of area and the design of the street were important for the snow quality. A clear relation between the pH and the quantity of suspended solids in the snow was found. Higher pH values were found in snow from sites with higher traffic loads, compared to sites with small quantities of particles which were the no-traffic sites. The dissolved fractions showed more complicated results. The concentration of the studied substances in the snow was affected by the precipitation at the site with no traffic. At the street where the snow was left beside the street, the concentration of substances increased with time, while the precipitation was of less importance. The mass loads of substances increased with time for both the streets, where the snow stayed in the vicinity of the street, and for the non-traffic site. For the site with traffic the snow handling operations evidently affected the mass loads. This was especially the case for particle-connected substances. As a result of the increased interest in reuse of friction material the sediment which remained along the streets after snow melt was studied with regard to physical and chemical characteristics. The side walk affected the amount of substances on the street more than the traffic load. For the streets without sidewalk an increased traffic load increased the amounts of sediment. The particle size distribution of the sediments swept from the street with a sidewalk differed from the distribution at the streets without a sidewalk. With two exceptions the smallest size fraction (>75 µm) had the largest concentration of heavy metals. For composite samples the concentration increased with traffic load. The pathways of pollutants in urban snow deposits have been studied in three different scales; laboratory, pilot, and full-scale. The initial snow, melt water and sediment were analysed with regard to chemical content. It was found that the dissolved substances to a great extent folowed with the melt water while for the particle bounded substances as much as 90-99% stayed in the sediment below the deposit. The dissolved substances left the snow in the beginning of the melt period, while the substances connected to particles showed a uniform release. The laboratory study showed that melt- freeze cycles delayed the release of substances. Almost all substances were attached to particles in the snow, while in the melt water a large part was in solution. It should be noted that a so-called acid shock was not found during these studies.
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| 7. |
- Viklander, Maria
(författare)
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Substances in Urban Snow : A comparison of the contamination of snow in different parts of the city of Luleå, Sweden
- 1999
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Ingår i: Water, Air and Soil Pollution. - 0049-6979 .- 1573-2932. ; 114:3-4, s. 377-394
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to investigate how the quality of snow varies within a city. The study area is situated in the Luleå municipality, in northern Sweden (lat. 65°35'N and long. 22°10'E). For this study, the city was divided into three different types of areas: housing areas, city centre and outskirts. In one area of each type, sampling sites were selected. Snow samples were taken at nine occasions, once every fourteenth day in the city centre and in the housing area. Analyses were carried out for pH, conductivity, suspended solids and both the total and dissolved concentration of phosphorus and selected metals. It was concluded that traffic or activities related to traffic were a major source of heavy metals and phosphorus in urban snow, both in the city centre and in the housing area. Also, the type of area and the design of the street were important for the quality of snow. A clear relation was found between the pH and the quantity of suspended solids in the snow. Higher pH values were found in snow samples from sites with higher traffic loads, and lower pH values at sites, which were the no-traffic sites, with small quantities of particles. The particulate and dissolved substances in the snow behaved in different ways.
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| 8. |
- Viklander, Maria
(författare)
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Urban snow deposits : pathways of pollutants
- 1996
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 189-190, s. 379-384
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Tidskriftsartikel (refereegranskat)abstract
- The pathways of pollutants in urban snow deposits have been studied in the laboratory, in a pilot study and at an actual deposit. The fractions of dissolved and particle-bound substances in the snow and melt water were studied. The results showed that almost all substances in the snow were attached to particles, while in the melt water more than 50% of most substances were dissolved. A large part of the substances which were attached to particles stayed in the sediment below the deposit, while the dissolved substances were mainly removed with the melt water.
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