| 1. |
- Bragée, Petra, et al.
(författare)
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Lake ecosystem responses to catchment disturbance and airborne pollution: an 800-year perspective in southern Sweden
- 2013
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Ingår i: Journal of Paleolimnology. - : Springer Verlag (Germany). - 0921-2728 .- 1573-0417. ; 50:4, s. 545-560
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Tidskriftsartikel (refereegranskat)abstract
- Sediment sequences spanning the last 800 years from two small lakes in the south Swedish uplands were explored for assessment of effects of changing human population, local land-use practices and airborne pollution on lake-ecosystem functioning and resilience. Variations in nutrient cycling and deposition of lithogenic elements were studied, using a multi-proxy stratigraphic approach. Carbon and nitrogen elemental and isotopic analyses were applied in combination with records of hydrocarbons (n-alkanes) to investigate the sources and depositional conditions of sediment organic matter. Changes in fluvial and airborne delivery of inorganic matter were based on X-ray fluorescence measurements. The results reveal that population growth and related increases in land-use pressure had a major impact on catchment erosion and input of terrestrial organic matter to the lakes from the 1500s to the end of the 1800s. Evidence also exists of a brief period of catchment disturbance at ca. 1200-1300, followed by recovery, likely connected to the Black Death pandemic. At ca. 1900 synchronous shifts in most of the proxy records suggest a marked change in external forcing common to the two lakes related to a major decrease in population density and the introduction of modern forestry following the industrial revolution. Interestingly, the two sediment records exhibit generally coherent trends in C/N ratio, organic C content and delta C-13, both before and after 1900, indicating broadly similar sensitivities of the lake ecosystems to human impact. In contrast, deviating trends in total N content, delta N-15 and lithogenic element concentrations (K, Ti, Rb and Zr) reflect site-specific responses to local disturbances during the last century due to different nutrient conditions and catchment properties. Our companion sediment records highlight the importance of understanding long-term human impact on watersheds and demonstrate how regional versus local forcing of lake ecosystems, as well as site-specific responses related to catchment characteristics can be reconstructed.
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| 2. |
- Canfield, Donald E., et al.
(författare)
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Oxygen dynamics in the aftermath of the Great Oxidation of the Earth’s atmosphere.
- 2013
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Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 110:42, s. 16736-16741
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Tidskriftsartikel (refereegranskat)abstract
- The oxygen content of Earth’s atmosphere has varied greatly through time, progressing from exceptionally low levels before about 2.3 billion years ago, to much higher levels afterward. In the absence of better information, we usually view the progress in Earth’s oxygenation as a series of steps followed by periods of relative stasis. In contrast to this view, and as reported here, a dynamic evolution of Earth’s oxygenation is recorded in ancient sediments from the Republic of Gabon from between about 2,150 and 2,080 million years ago. The oldest sediments in this sequence were deposited in well-oxygenated deep waters whereas the youngest were deposited in euxinic waters, which were globally extensive. These fluctuations in oxygenation were likely driven by the comings and goings of the Lomagundi carbon isotope excursion, the longest–lived positive ?13C excursion in Earth history, generating a huge oxygen source to the atmosphere. As the Lomagundi event waned, the oxygen source became a net oxygen sink as Lomagundi organic matter became oxidized, driving oxygen to low levels; this state may have persisted for 200 million years.
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| 3. |
- Digerfeldt, Gunnar, et al.
(författare)
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Reconstruction of Holocene lake-level changes in Lake Igelsjon, southern Sweden
- 2013
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Ingår i: GFF. - : Informa UK Limited. - 2000-0863 .- 1103-5897. ; 135:2, s. 162-170
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Tidskriftsartikel (refereegranskat)abstract
- Pollen and sediment stratigraphic analyses of a transect of core sequences are used to reconstruct Holocene lake-level changes in Lake Igelsjon, southern Sweden. The pattern of changes seen in the records is related to climatic/hydrological changes and agrees principally with the pattern characteristically found in lakes in southern Sweden. However, compared with an earlier study based on isotopic analysis of lake sediments by Hammarlund et al. (2003), some significant differences are found in the early Holocene, and possible explanations for these differences are discussed.
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| 4. |
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| 5. |
- Edvardsson, Johannes, et al.
(författare)
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Exploring climate forcing of growth depression in subfossil South Swedish bog pines using stable isotopes
- 2014
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Ingår i: Dendrochronologia. - : Elsevier BV. - 1125-7865. ; 32:1, s. 55-61
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Tidskriftsartikel (refereegranskat)abstract
- Comparison between growth variability, based on ring-width (RW) analysis, and moisture-sensitive signals in tree-ring carbon and oxygen stable-isotope composition provides increased understanding of how climate and hydrology influenced bog pines (Pinus sylvestris L) at two sites in southern Sweden during the mid- and late Holocene. Tree-ring sequences from two subfossil trees collected at raised bogs having different hydrology and catchment size were analyzed to probe the stable-isotope signals associated with two bog-wide episodes of growth depression, one during the Holocene Thermal Maximum and the other during the Neoglacial Transition. The occurrence of lower whole-wood delta C-13 and cellulose 813C and 8180 values immediately prior to the onset of growth depression in both trees, suggesting increased atmospheric relative humidity, is consistent with the notion that excessive effective moisture impeded tree growth. Correlation analysis indicates that the growth response lagged about three years behind the decline in delta C-13 and delta O-18 values in each tree, possibly reflecting relatively slow rise in the local water table in response to wetter climate. (c) 2013 Elsevier GmbH. All rights reserved.
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| 6. |
- Edvardsson, Johannes, et al.
(författare)
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Holocene peatland development and hydrological variability inferred from bog-pine dendrochronology and peat stratigraphy - a case study from southern Sweden
- 2012
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Ingår i: Journal of Quaternary Science. - : Wiley. - 1099-1417 .- 0267-8179. ; 27:6, s. 553-563
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Tidskriftsartikel (refereegranskat)abstract
- Dendrochronological analysis was applied to subfossil remains of Scots pine (Pinus sylvestris L.) buried in a South Swedish peat deposit. In combination with peat stratigraphy, this approach was explored for its potential to provide information on the local hydrological and depositional history at the site, forming the basis for a regional palaeohydrological analysis. A 726-year ring-width chronology was developed and assigned an absolute age of 7233-6508cal a BP (5284-4559 BC) through cross-dating with German bog-pine chronologies, whereas two short additional records of older ages were radiocarbon dated. Registration of growth positions of individual trees allowed assessment of the spatial dynamics of the pine population in response to hydrological changes and peatland ontogeny. Annually resolved growth variability patterns in the pine population reveal several establishment and degeneration phases, probably reflecting fluctuations in bog-surface wetness. A major establishment phase at 7200-6900?cal a BP reflects the onset of a period of lowered groundwater level, also indicated by increased peat humification, and a development consistent with regional temperature and lake level reconstructions revealed from other proxies. This study demonstrates that subfossil bog-pine populations may provide annually to decadally resolved reconstructions of local groundwater variability, which are highly relevant in a long-term palaeoclimatic context. Copyright (c) 2012 John Wiley & Sons, Ltd.
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| 7. |
- Edvardsson, Johannes, et al.
(författare)
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Late-Holocene expansion of a south Swedish peatland and its impact on marginal ecosystems: Evidence from dendrochronology, peat stratigraphy and palaeobotanical data
- 2014
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Ingår i: The Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 24:4, s. 466-476
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a reconstruction of the long-term development and lateral expansion of a south Swedish peat bog was performed using a multi-proxy approach, including dendrochronology, peat stratigraphy and macrofossil and pollen analyses. By combining mapping of cross-dated subfossil trees with radiocarbon-dated peat sequences, an improved approach to reconstruction of lateral peat expansion was applied. Apart from providing approximate ages of tree burial episodes, the ring-width records offer information on hydrological variations prior to the bog expansion. New bog oak, pine and alder chronologies are presented and their potential as a dating tool for peatland expansion as well as for local to regional environmental interpretations is examined. Our tree-replication records show that increased amounts of bog trees in the central parts can be linked to drier bog-surface conditions, whereas an increase in wood remains in the marginal zone is related to enhanced preservation due to lateral bog expansion. Our reconstructions of the development of the peat deposit and associated changes in the distribution of vegetation communities provide new insight into peatland responses to climate change at the end of the 'Holocene Thermal Maximum' (5000-4000 cal. yr BP).
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| 8. |
- Edvardsson, Johannes, et al.
(författare)
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South Swedish bog pines as indicators of Mid-Holocene climate variability
- 2012
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Ingår i: Dendrochronologia. - : Elsevier BV. - 1125-7865. ; 30:2, s. 93-103
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Tidskriftsartikel (refereegranskat)abstract
- Dendroclimatic investigations of subfossil Scots pine (Pinus sylvestris) from two raised bogs in southern Sweden yielded a continuous floating 1492-year long tree-ring record. By cross-dating with bog-pine chronologies from Lower Saxony, Germany, the South Swedish record was assigned an absolute age of 5219-3728 BC. The cross-match between ring-width chronologies from these two regions, separated by 500-700 km, is remarkably strong and the correlation positive, which indicates that large-scale climate dynamics had a significant impact on the growth of bog pines during the Holocene Thermal Maximum (HTM) when bog-pine distribution reached a maximum in both regions. However, local population dynamics were also influenced by peatland ontogeny and competition, as shown by differences in replication and mean tree age between the Swedish and German records. Comparisons with chronologies developed from modern bog pines in southern Sweden indicate that more coherent climate was controlling pine growth on natural peatlands during warm periods in the past. This study demonstrates the usefulness of Swedish subfossil bog-pine material as a climate proxy, with particular potential for decadal- to centennial-scale reconstructions of humidity fluctuations. (C) 2011 Istituto Italiano di Dendrocronologia. Published by Elsevier GmbH. All rights reserved.
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| 9. |
- Gillespie, Ulrika, et al.
(författare)
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Effects of Pharmacists' Interventions on Appropriateness of Prescribing and Evaluation of the Instruments' (MAI, STOPP and STARTs') Ability to Predict Hospitalization-Analyses from a Randomized Controlled Trial
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:5, s. e62401-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Appropriateness of prescribing can be assessed by various measures and screening instruments. The aims of this study were to investigate the effects of pharmacists' interventions on appropriateness of prescribing in elderly patients, and to explore the relationship between these results and hospital care utilization during a 12-month follow-up period. Methods: The study population from a previous randomized controlled study, in which the effects of a comprehensive pharmacist intervention on re-hospitalization was investigated, was used. The criteria from the instruments MAI, STOPP and START were applied retrospectively to the 368 study patients (intervention group (I) n = 182, control group (C) n = 186). The assessments were done on admission and at discharge to detect differences over time and between the groups. Hospital care consumption was recorded and the association between scores for appropriateness, and hospitalization was analysed. Results: The number of Potentially Inappropriate Medicines (PIMs) per patient as identified by STOPP was reduced for I but not for C (1.42 to 0.93 vs. 1.46 to 1.66 respectively, p<0.01). The number of Potential Prescription Omissions (PPOs) per patient as identified by START was reduced for I but not for C (0.36 to 0.09 vs. 0.42 to 0.45 respectively, p<0.001). The summated score for MAI was reduced for I but not for C (8.5 to 5.0 and 8.7 to 10.0 respectively, p<0.001). There was a positive association between scores for MAI and STOPP and drug-related readmissions (RR 8-9% and 30-34% respectively). No association was detected between the scores of the tools and total re-visits to hospital. Conclusion: The interventions significantly improved the appropriateness of prescribing for patients in the intervention group as evaluated by the instruments MAI, STOPP and START. High scores in MAI and STOPP were associated with a higher number of drug-related readmissions.
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| 10. |
- Ilyashuk, Elena A., et al.
(författare)
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Holocene climate variability on the Kola Peninsula, Russian Subarctic, based on aquatic invertebrate records from lake sediments
- 2013
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Ingår i: Quaternary Research. - : Cambridge University Press (CUP). - 0033-5894 .- 1096-0287. ; 79:3, s. 350-361
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Tidskriftsartikel (refereegranskat)abstract
- Sedimentary records of invertebrate assemblages were obtained from a small lake in the Khibiny Mountains, Kola Peninsula. Together with a quantitative chironomid-based reconstruction of mean July air temperature, these data provide evidence of Holocene climate variability in the western sector of the Russian Subarctic. The results suggest that the amplitude of climate change was more pronounced in the interior mountain area than near the White Sea coast. A chironomid-based temperature reconstruction reflects a warming trend in the early Holocene, interrupted by a transient cooling at ca. 8500-8000 cal yr BP with a maximum drop in temperature (ca. 1 degrees C) around 8200 cal yr BP. The regional Holocene Thermal Maximum, characterized by maximum warmth and dryness occurred at ca. 7900-5400 cal yr BP. During this period, July temperatures were at least 1 C higher than at present. The relatively warm and dry climate persisted until ca. 4000 cal yr BP, when a pronounced neoglacial cooling was initiated. Minimum temperatures, ca. 1-2 degrees C lower than at present, were inferred at ca. 3200-3000 cal yr BP. Faunal shifts in the stratigraphic profile imply also that the late-Holocene cooling was followed by a general increase in effective moisture. (C) 2013 University of Washington. Published by Elsevier Inc. All rights reserved.
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