| 1. |
- Larsson, Per
(författare)
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Atmospheric deposition of persistent pollutants governs uptake in freshwater zooplankton
- 1989
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844 .- 0004-6981. ; 23:10, s. 2151-2158
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Tidskriftsartikel (refereegranskat)abstract
- The atmospheric fallout of PCBs, ∑DDT and γ-HCH (lindane) to a pond in southern Sweden was studied in relation to uptake by freshwater Zooplankton. The extent of the atmospheric deposition of PCBs and lindane was reflected in the uptake by the Zooplankton; high deposition in the spring and autumn resulted in high uptake by the organisms while a lower uptake during summer was a result of lower deposition. The atmospheric deposition of ∑DDT was dominated by p,p-DDT, p,p-DDE and o,p-DDT, while p,p-DDE and p,p-DDD were dominant in Zooplankton. These differences in ∑DDT composition are probably attributed to microbial conversion; as a result, levels in the Zooplankton appeared not to be governed by atmospheric deposition. The availability of the previously airborne, persistent pollutants to Zooplankton was a function of the compounds chemical properties, e.g. water solubility, and the form of deposition. The results show that atmospheric deposition is an important route by which persistent pollutants are transported to Holarctic, aquatic ecosystems.
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| 2. |
- Larsson, Per, et al.
(författare)
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Atmospheric transport of chlorinated hydrocarbons to Sweden 1985 compared to 1973
- 1989
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844 .- 0004-6981. ; 23:8, s. 1699-1711
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Tidskriftsartikel (refereegranskat)abstract
- The atmospheric fallout of DDT and DDE (ΣDDT) over Sweden has decreased during the last decade. Today long-range transport from southern sources outside the country dominates the inflow. This was reflected in a decreasing south-to-north gradient of the compounds in atmospheric deposition and in the lower atomosphere. The fallout of PCBs was similar in 1984–1985 and 1972–1973, and today local contamination by combustion is more prominent than it was 10 years ago, even though PCB restrictions have been in force during the interim. Since PCB deposition is higher in the coastal areas than in the inland regions, other sources, such as volatilization from the seas and long-range transport also contribute to PCBs in fallout. The levels of PCB and ΣDDT in the lower atmosphere were positively correlated with temperature. Consequently, the compounds tended to be in the gas phase during the warmer summer period whereas during winter they were more liable to be adsorbed to particles, partition to airborne water and contribute in fallout. From each sampling station a chromatographic 'fingerprint' of pollutants in airborne fallout and in the lower atmosphere was obtained. The fingerprint was the combined result of the station's location and climate. The results show that considerable amounts of chlorinated pollutants are being transported to and within Sweden via the atmosphere.
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| 3. |
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| 4. |
- Wiman, Bo, et al.
(författare)
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Aerosol characteristics in a mature coniferous forest - methodology, composition, sources and spatial concentration variations
- 1985
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844 .- 0004-6981. ; 19:2, s. 349-362
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Tidskriftsartikel (refereegranskat)abstract
- A forest site in southern Sweden representative of a wider range of coniferous forest Londscapes has been characterized with respect to aerosol composition (NO−3, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn. Br and Pb). In one series aerosol sampling was carried out simultaneously along a horizontal transect with four stations, one located in open field, one at the forest edge and two within the forest. In another series simultaneous sampling was performed along a vertical transect with four sampling points, one located below but near the canopy top and the others further downwards through the canopy (height c. 25 m). Sampling strategy and analytical methods are presented in detail. Statistical analyses of concentration data suggest that K, Ca, Ti, Mn and Fe in the coarse particle fractions originated from soil, whereas other components (S, V, Cu and Pb) were of mainly anthropogenic origin. Depletion of coarse fraction concentrations within the forest was detected for several elements, whereas spatial variations of fine fraction concentrations showed weak or no systematic trends. This result is interpreted as a net effect of counteracting mechanisms in the forest: losses due to deposition and inputs due to turbulence and gravitationally settling particles.
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| 5. |
- Wiman, Bo, et al.
(författare)
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Aerosol concentration profiles within a mature coniferous forest - model versus field results
- 1985
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844 .- 0004-6981. ; 19:2, s. 363-367
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Tidskriftsartikel (refereegranskat)abstract
- Aerosol mass concentration profiles along a horizontal and a vertical transect in a forest are modelled from field site information on aerosol particle size distributions, forest structure and aerodynamics. Model outputs are compared with concentration profiles obtained from field measurements at the site. The comparisons suggest that model properties are qualitatively valid. Though field data are insufficient for a systematic quantitative test of model behaviour, the investigation does not indicate any quantitatively fundamental model deficiencies.
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| 6. |
- Wiman, Bo, et al.
(författare)
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Aerosol depletion and deposition in forests - a model analysis
- 1985
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844 .- 0004-6981. ; 19:2, s. 335-347
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Tidskriftsartikel (refereegranskat)abstract
- A system of partial differential equations is developed to describe an aerosol entering from an open field into a downwind forest, where deposition and turbulent transfer affect particle concentration. The model considers the interplay between forest structure, open field and forest aerodynamics and aerosol characteristics. The modelling problem is broken down into a set of simpler submodels which can be refined or simplified individually. Model results suggest, basically, significant horizontal (vertical) depletion of super-μm particles downwind from the forest edge (downwards from the canopy top). Distinct edge effects in deposition rates are common. In certain cases vertical exchange processes predominate, leading to enrichment of the aerosol. Sub-μm particles (unless extremely small) are subject to almost negligible depletion and edge effects. Deposition of super-μm particle oriented aerosols are governed by a complex interaction between particle size, forest structure and aerodynamics whereas deposition of sub-μm particles is simply controlled by particle concentration and forest structure. Under certain conditions (dense homogenous forests) aerosol particle concentration across the open field to forest roughness transition increases again after initial depletion.
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