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- Maljanen, M, et al.
(författare)
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Nitrous oxide production in boreal soils with variable organic matter content at low temperature – snow manipulation experiment
- 2009
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Ingår i: Biogeosciences. - : Copernicus Publications on behalf of the European Geosciences Union. - 1726-4170 .- 1726-4189. ; 6:11, s. 2461-73
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Tidskriftsartikel (refereegranskat)abstract
- Agricultural soils are the most important sources for the greenhouse gas nitrous oxide (N2O), which is produced and emitted from soils also at low temperatures. The processes behind emissions at low temperatures are still poorly known. Snow is a good insulator and it keeps soil temperature rather constant. To simulate the effects of a reduction in snow depth on N2O emission in warming climate, snow pack was removed from experimental plots on three different agricultural soils (sand, mull, peat). Removal of snow lowered soil temperature and increased the extent and duration of soil frost in sand and mull soils. This led to enhanced N2O emissions during freezing and thawing events. The cumulative emissions during the first year when snow was removed over the whole winter were 0.25, 0.66 and 3.0 g N2O-N m−2 yr−1 in control plots of sand, mull and peat soils, respectively. In the treatment plots, without snow cover, the respective cumulative emissions were 0.37, 1.3 and 3.3 g N2O-N m−2 yr−1. Shorter snow manipulation during the second year did not increase the annual emissions. Only 20% of the N2O emission occurred during the growing season. Thus, these results highlight the importance of the winter season for this exchange and that the year-round measurements of annual N2O emissions from boreal soils are integral for estimating their N2O source strength. N2O accumulated in the frozen soil during winter and the soil N2O concentration correlated with the depth of frost but not with the winter N2O emission rates per se. Also laboratory incubations of soil samples showed high production rates of N2O at temperatures below 0°C, especially in the sand and peat soils.
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- Espelt, A., et al.
(författare)
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Socioeconomic inequalities in diabetes mellitus across Europe at the beginning of the 21st century
- 2008
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 0012-186X .- 1432-0428. ; 51:11, s. 1971-1979
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Tidskriftsartikel (refereegranskat)abstract
- In Europe, educational attainment and diabetes are inversely related, in terms of both morbidity and mortality rates. This underlines the importance of targeting interventions towards low SEP groups. Access and use of healthcare services by people with diabetes also need to be improved.
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- Hussein, Tareq, et al.
(författare)
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Observation of regional new particle formation in the urban atmosphere
- 2008
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Ingår i: Tellus. Series B, Chemical and physical meteorology. - : Stockholm University Press. - 0280-6509 .- 1600-0889. ; 60:4, s. 509-521
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Tidskriftsartikel (refereegranskat)abstract
- Long-term measurements of fine particle number-size distributions were carried out over 9.5 yr (May 1997-December 2006), in the urban background atmosphere of Helsinki. The total number of days was 3528 with about 91.9% valid data. A new particle formation event (NPF) is defined if a distinct nucleation mode of aerosol particles is observed below 25 nm for several hours, and it shows a growth pattern. We observed 185 NPF events, 111 d were clear non-events and most of the days (around 83.5%) were undefined. The observed events were regional because they were observed at Hyytiala (250 km north of Helsinki). The events occurred most frequently during spring and autumn. The observed formation rate was maximum during the spring and summer (monthly median 2.87 cm(-3) s(-1)) and the modal growth rate was maximum during late summer and Autumn (monthly median 6.55 mm h(-1)). The events were observed around noon, and the growth pattern often continued on the following day. The observation of weak NPF events was hindered due to pre-existing particles from both local sources. It is clear that regional NPF events have a clear influence oil the dynamic behaviour of aerosol particles in the urban atmosphere.
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