| 1. |
- Apolinarska, Karina, et al.
(författare)
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Multi-component stable isotope records from Late Weichselian and early Holocene lake sediments at Imiolki, Poland: palaeoclimatic and methodological implications
- 2009
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Ingår i: Journal of Quaternary Science. - : Wiley. - 1099-1417 .- 0267-8179. ; 24:8, s. 948-959
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Tidskriftsartikel (refereegranskat)abstract
- Late Weichselian and early Holocene climatic and environmental changes are inferred from stable carbon and oxygen isotope records obtained on bulk and biogenic carbonates from the sediment sequence of Lake Lednica, western Poland. Along with sediment and pollen stratigraphic data, a wide range of carbonate components occurring in the sediments was analysed for delta C-13 and delta O-18, including shells of several gastropod species and the bivalve genus Pisidium, carapaces of the ostracod subfamily Candoninae and oogonia of the aquatic macrophyte genus Chara. The development of catchment soils and the onset of authigenic carbonate production in response to the climatic amelioration during the Late Weichselian are clearly reflected by rising carbonate content, distinct isotopic shifts in bulk carbonates and decreasing delta C-13 values of bulk organic matter in the sediments. The GI-1/GS-1 (the Bolling-Allerod Interstadial complex/Younger Dryas Stadial) and the GS-1/Preboreal transitions are marked by significant shifts in delta O-18 values of 2-3 parts per thousand, as well as by distinct changes in carbonate content, indicative of a decrease and a subsequent increase in mean annual temperature. Corresponding delta C-13 records reflect primarily changes in aquatic productivity, with favourable conditions for phytoplankton and macrophytes during GI-1 and the Preboreal resulting in persistent C-13 enrichment. The Younger Dryas Stadial is characterised by depletions in C-13 and O-18, with indications of a climatic tripartition. Consistent offsets in delta C-13 and delta O-18 between records obtained on specific carbonate components reflect vital effects in combination with seasonal characteristics and habitat preferences of the respective carbonate-precipitating biota. Largely parallel first-order variations in delta C-13 and delta O-18 of the different carbonate components demonstrate that individual isotope records may provide important palaeoclimatic information, although more detailed reconstructions can be obtained from multi-component analysis. Copyright (C) 2009 John Wiley & Sons, Ltd.
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| 2. |
- Barnekow, Lena, et al.
(författare)
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Boreal forest dynamics in north-eastern Sweden during the last 10,000 years based on pollen analysis
- 2008
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Ingår i: Vegetation History and Archaeobotany. - : Springer Science and Business Media LLC. - 0939-6314 .- 1617-6278. ; 17:6, s. 687-700
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Tidskriftsartikel (refereegranskat)abstract
- A pollen record obtained from a 2.2-m sediment succession deposited in a small lake in the province of Vasterbotten, north-eastern Sweden, reveals the presence of continuous forest cover since 8,500 calendar years before present (cal B.P.). Forest with abundant Pinus (pine) and Betula (birch) initially colonized the area, followed by a dominance of deciduous trees, primarily Betula, from ca. 8,000 to ca. 3,200 cal B.P. Pollen accumulation rates of Quercus (oak), Ulmus (elm) and Tilia (linden) suggest the possible local presence of these thermophilous tree species during this period. The climate gradually became colder and moister around 3,500 cal B.P. and an increased abundance of Sphagnum spores indicates paludification. Picea (spruce) became established around 3,200 cal B.P. and less than 500 years later this was the dominant tree species around the lake. The fire frequency as inferred from charcoal particles exhibits a general increase from ca. 3,000 cal B.P. with subsequent charcoal accumulation maxima at around 2,800 cal B.P., 1,700 cal B.P. and in recent time. The human influence on vegetation was significant during the last 200-300 years. Soil erosion increased substantially and fern spores amount to ca. 55% of the total pollen assemblage in the uppermost samples. These results suggest an extensive anthropogenic impact on the local forest ecosystem, with abundant logging, burning and ditching in the vicinity of the lake. Independent evidence of sub-recent human-induced environmental change is provided by historical accounts. Complementary information on catchment soil development and aquatic nutrient status was provided by records of magnetic susceptibility and elemental carbon, and nitrogen contents obtained from the same sediment core.
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| 3. |
- Bennike, Ole, et al.
(författare)
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Tristan da Cunha
- 2005
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Ingår i: Naturens Verden. - 0028-0895. ; 88:7/8, s. 10-23
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 4. |
- Bergman, Jonas, et al.
(författare)
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Deglacial vegetation succession and Holocene tree-limit dynamics in the Scandes Mountains, west-central Sweden: stratigraphic data compared to megafossil evidence
- 2005
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Ingår i: Review of Palaeobotany and Palynology. - : Elsevier BV. - 0034-6667. ; 134:3-4, s. 129-151
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Forskningsöversikt (refereegranskat)abstract
- High-resolution records of plant macrofossils, magnetic susceptibility, and total carbon content, complemented by pollen data, were obtained from a postglacial lake sediment sequence at alpine Lake Stentjarn (987 m a.s.l.), in west-central Sweden. Holocene vegetational and environmental changes were reconstructed from the data, with particular emphasis on the deglacial establishment of terrestrial vegetation and subsequent tree-limit dynamics. A short-lived pioneer flora with Geum rivale, Dryas octopetala, Empetrum nigrum, Ledum palustre, Saxifraga sp., Salix spp., and Oxyria digyna established locally following deglaciation at c. 10,500 cat year BP. The pioneer flora was out-competed by establishing Betula pubescens and grasses at c. 10,300 cat year BP. Subsequent local expansions of B. pubescens at c. 9800 cat year BP and Pinus sylvestris at c. 9200 cal year BP were followed by a temporary retraction of the birch tree-limit and a permanent retreat of pine between 8500 and 8000 cat year BP, accompanied by declining aquatic productivity and increasing catchment erosion. A gradual decrease in forest density initiated at c. 6000 cat year BP led to a retreat of the birch tree-limit from the lake catchment at c. 3500 cat year BP, followed by persistence of scattered trees until c. 2000 cat year BP. A mosaic heath vegetation dominated by Empetrum nigrum and Betula nana developed at c, 3500 cat year BP. Comparison of the stratigraphic data from Lake Stenljiirn with records of radiocarbon-dated subfossil wood remains (megafossils) obtained from adjacent areas during recent decades revealed a high level of consistency of the inferred tree-limit variations for P. sylvestris, B. pubescens, and Alnus incana. Chronological control was established by radiocarbon dating of terrestrial macrofossils and geochemical identification of a tephra horizon originating from the Icelandic Askja- 1875 eruption.
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| 5. |
- Davies, SM, et al.
(författare)
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Cryptotephra sedimentation processes within two lacustrine sequences from west central Sweden
- 2007
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Ingår i: The Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 17:3, s. 319-330
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Tidskriftsartikel (refereegranskat)abstract
- Distal tephra horizons, particularly within lacustrine sequences, are increasingly being used as time-synchronous marker horizons within palaeoclimatic and palaeoenvironmental investigations. As sedimentary features marking the presence of these so-called cryptotephras are absent to the naked eye, it is of some importance that the stratigraphic position representing primary airfall, and likewise the timing Of the volcanic event, is accurately and consistently recorded amongst these deposits. Often tephra shards from a cryptotephra deposit can be found spanning several centimetres of sediments within lacustrine and peat sequences. Very few studies, however, have looked in detail at the sedimentation and vertical distribution of cryptotephra deposits within such sequences and, more importantly, the criteria for defining the correct stratigraphic position of the volcanic event. Two sediment cores from Lake Spaime and Lake Getvaltjarnen, west central Sweden are employed to investigate in detail the vertical distribution of the tephra shards derived from the AD 1875 eruption of the Askja volcano in Iceland. Detailed geochemical analysis of shards from both records indicate that products of the Askja eruption are present for at least 120 years and thus emphasize the importance of carefully identifying the correct horizon that marks the timing of the volcanic event rather than shards resulting from a period of reworking or downward migration. Both sites yield contrasting shard concentration profiles and thus raise a number of questions regarding the influence of site-specific processes on cryptotephra sedimentation, particularly the role of snow-beds acting as tephra traps, the possibility of reworking, and downward migration of shards in soft sediment. A second tephra is also identified at Lake Getvaltjarnen and is believed to originate from the AD 1477 Veidivotn eruption and represents the first occurrence of this tephra outside of Iceland.
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| 6. |
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| 7. |
- de Jong, Rixt, et al.
(författare)
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Late Holocene effective precipitation variations in the maritime regions of south-west Scandinavia
- 2009
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791. ; 28:1-2, s. 54-64
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Tidskriftsartikel (refereegranskat)abstract
- At present, the climate in south-west Scandinavia is predominantly controlled by westerlies carrying moist Atlantic air, which forms a main source of precipitation in all seasons. Past variations in the ratio between precipitation and evaporation (effective precipitation) from terrestrial sites, however, may indicate changes in the degree of maritime influence. Palaeoclimatic archives in this region are thus ideally situated to study past changes in atmospheric circulation patterns. In this study, multi-proxy comparisons of records from three peat bogs and two lakes are used to reconstruct regional-scale variations of effective precipitation in south-west Sweden during the Late Holocene. The total aeolian sediment influx into two peat bogs is used as a proxy for storm activity. The frequency of storm phases increases strongly after ca 2500 cal yrs BP. Dry conditions occur on a regional scale around 4800-4400, 2000-1700, 1300-1000, 700-500 and 300-100 cal yrs BP. In addition, a comparison to winter precipitation reconstructed from four Norwegian glaciers shows similar variations during the past ca 2000 years. This indicates that the climate in both regions was controlled by large-scale atmospheric circulation dynamics of the North Atlantic region. The strong variability of effective precipitation and storm activity after ca 2500 cal yrs BP indicates a highly variable climate. (C) 2008 Elsevier Ltd. All rights reserved.
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| 8. |
- Gillespie, Ulrika, et al.
(författare)
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A comprehensive pharmacist intervention to reduce morbidity in patients 80 years or older : a randomized controlled trial
- 2009
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Ingår i: Archives of Internal Medicine. - : American Medical Association (AMA). - 0003-9926 .- 1538-3679. ; 169:9, s. 894-900
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUNDPatients 80 years or older are underrepresented in scientific studies. The objective of this study was to investigate the effectiveness of interventions performed by ward-based pharmacists in reducing morbidity and use of hospital care among older patients.METHODSA randomized controlled study of patients 80 years or older was conducted at the University Hospital of Uppsala, Uppsala, Sweden. Four hundred patients were recruited consecutively between October 1, 2005, and June 30, 2006, and were randomized to control (n = 201) and intervention (n = 199) groups. The interventions were performed by ward-based pharmacists. The control group received standard care without direct involvement of pharmacists at the ward level. The primary outcome measure was the frequency of hospital visits (emergency department and readmissions [total and drug-related]) during the 12-month follow-up period.RESULTSThree hundred sixty-eight patients (182 in the intervention group and 186 in the control group) were analyzed. For the intervention group, there was a 16% reduction in all visits to the hospital (quotient, 1.88 vs 2.24; estimate, 0.84; 95% confidence interval [CI], 0.72-0.99) and a 47% reduction in visits to the emergency department (quotient, 0.35 vs 0.66; estimate, 0.53; 95% CI, 0.37-0.75). Drug-related readmissions were reduced by 80% (quotient, 0.06 vs 0.32; estimate, 0.20; 95% CI, 0.10-0.41). After inclusion of the intervention costs, the total cost per patient in the intervention group was $230 lower than that in the control group.CONCLUSIONIf implemented on a population basis, the addition of pharmacists to health care teams would lead to major reductions in morbidity and health care costs.
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| 9. |
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| 10. |
- Hammarlund, Dan, et al.
(författare)
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A sedimentary record of the rise and fall of the metal industry in Bergslagen, south central Sweden
- 2008
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Ingår i: Journal of Paleolimnology. - : Springer Science and Business Media LLC. - 0921-2728 .- 1573-0417. ; 39:4, s. 463-475
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Tidskriftsartikel (refereegranskat)abstract
- Detailed stratigraphic analyses of sediments deposited in Lake Botjarnen, a small boreal forest lake in the shield terrain of central Sweden, clearly reflect progressively increasing human impact on terrestrial and aquatic ecosystems following settlement and establishment of an iron industry in the 17th century. Rising frequencies of pollen and spores from light-demanding plants provide evidence of extensive forest clearance for charcoal and timber production, which peaked in the early 20th century. An associated increase in catchment erosion is reflected by changing carbon and nitrogen elemental content and carbon-isotope composition of sediment organic matter and by increased magnetic susceptibility of the sediments. Records of air-borne pollutants (lead, zinc and sulphur) can be correlated to the development of local and regional mining and metal industry as inferred from historical accounts. Rapid recession of the iron industry led to re-forestation and recovery of the aquatic nutrient status to pre-industrial conditions over the past 100 years. The chronology of the sediment succession, which is based on Pb-210 and Cs-137 radionuclide data in combination with radiocarbon dating, is confirmed by historical lead pollution trends established for the region.
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