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| 2. |
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| 3. |
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| 4. |
- Bentley, Michael J., et al.
(författare)
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A community-based geological reconstruction of Antarctic Ice Sheet deglaciation since the Last Glacial Maximum
- 2014
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 100, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- A robust understanding of Antarctic Ice Sheet deglacial history since the Last Glacial Maximum is important in order to constrain ice sheet and glacial-isostatic adjustment models, and to explore the forcing mechanisms responsible for ice sheet retreat. Such understanding can be derived from a broad range of geological and glaciological datasets and recent decades have seen an upsurge in such data gathering around the continent and Sub-Antarctic islands. Here, we report a new synthesis of those datasets, based on an accompanying series of reviews of the geological data, organised by sector. We present a series of timeslice maps for 20 ka, 15 ka, 10 ka and 5 ka, including grounding line position and ice sheet thickness changes, along with a clear assessment of levels of confidence. The reconstruction shows that the Antarctic Ice sheet did not everywhere reach the continental shelf edge at its maximum, that initial retreat was asynchronous, and that the spatial pattern of deglaciation was highly variable, particularly on the inner shelf. The deglacial reconstruction is consistent with a moderate overall excess ice volume and with a relatively small Antarctic contribution to meltwater pulse la. We discuss key areas of uncertainty both around the continent and by time interval, and we highlight potential priorities for future work. The synthesis is intended to be a resource for the modelling and glacial geological community.
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| 5. |
- Blanck, Sara, 1980-
(författare)
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Elever möter samhällsfrågor : Didaktiska och bildningsteoretiska perspektiv på samhällsorienterande undervisning om epoktypiska samhällsfrågor
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Med utgångspunkt i didaktik och bildningsteoretiska perspektiv är syftet med denna avhandling att undersöka och analysera ämnesövergripande undervisning om epoktypiska samhällsfrågor i grundskolan för att utveckla kunskap om undervisningens didaktiska möjligheter och utmaningar.Avhandlingen är en sammanläggning och består av tre ingående texter: en licentiatuppsats om samhällskunskapsämnet i ämnesintegrerad undervisning som genomfördes 2012–2014 samt två artiklar från forskningsprojektet ”Att utveckla undervisning i samhällsfrågor: om didaktiska val i SO-ämnena i grundskolans mellanår 4-6” som genomfördes 2017–2022. I de empiriska undersökningarna användes olika metoder såsom observationer och ljudinspelning av undervisning, intervjuer med lärare, enkät, fokusgruppsintervjuer med elever samt forsknings- och utvecklingscirkel tillsammans med lärare. Vid analysen används didaktiska och bildningsteoretiska perspektiv för att analysera empirin. Resultaten presenteras i form av så kallade curriculumprinciper som kan fungera som utgångspunkter för lärares didaktiska analys, val och handlingar, när det kommer till undervisning om epoktypiska samhällsfrågor. Genom en analys av de didaktiska relationerna visas betydelsen av att lärarens didaktiska val görs utifrån ett relevant och kraftfullt innehåll som också blir meningsfullt för elevers samtid och framtid. Fyra curriculumprinciper föreslås som utgångspunkter för lärare när de planerar och genomför undervisning om epoktypiska samhällsfrågor. De två första principerna handlar om hur ett flerdimensionellt bildningsbegrepp, där kognitiva, etiska och estetiska dimensioner samverkar, kan utgöra en målsättning för undervisningen. Innehållet kan struktureras i ämnessamspel med skolämnenas olika bidrag till förståelsen av dessa komplexa samhällsfrågor. Den tredje och fjärde principen har utgångspunkt i dels elevers begreppsliga utveckling genom autentiska exempel och inferenser dels i hur lärares didaktiska val av exempel blir betydelsefulla för hur innehållet förstås av eleverna.
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| 6. |
- Blunden, Jessica, et al.
(författare)
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State of the Climate in 2012
- 2013
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Ingår i: Bulletin of The American Meteorological Society - (BAMS). - 0003-0007 .- 1520-0477. ; 94:8, s. S1-S258
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Tidskriftsartikel (refereegranskat)abstract
- For the first time in serveral years, the El Nino-Southern Oscillation did not dominate regional climate conditions around the globe. A weak La Ni a dissipated to ENSOneutral conditions by spring, and while El Nino appeared to be emerging during summer, this phase never fully developed as sea surface temperatures in the eastern conditions. Nevertheless, other large-scale climate patterns and extreme weather events impacted various regions during the year. A negative phase of the Arctic Oscillation from mid-January to early February contributed to frigid conditions in parts of northern Africa, eastern Europe, and western Asia. A lack of rain during the 2012 wet season led to the worst drought in at least the past three decades for northeastern Brazil. Central North America also experienced one of its most severe droughts on record. The Caribbean observed a very wet dry season and it was the Sahel's wettest rainy season in 50 years. Overall, the 2012 average temperature across global land and ocean surfaces ranked among the 10 warmest years on record. The global land surface temperature alone was also among the 10 warmest on record. In the upper atmosphere, the average stratospheric temperature was record or near-record cold, depending on the dataset. After a 30-year warming trend from 1970 to 1999 for global sea surface temperatures, the period 2000-12 had little further trend. This may be linked to the prevalence of La Ni a-like conditions during the 21st century. Heat content in the upper 700 m of the ocean remained near record high levels in 2012. Net increases from 2011 to 2012 were observed at 700-m to 2000-m depth and even in the abyssal ocean below. Following sharp decreases in to the effects of La Ni a, sea levels rebounded to reach records highs in 2012. The increased hydrological cycle seen in recent years continued, with more evaporation in drier locations and more precipitation in rainy areas. In a pattern that has held since 2004, salty areas of the ocean surfaces and subsurfaces were anomalously salty on average, while fresher areas were anomalously fresh. Global tropical cyclone activity during 2012 was near average, with a total of 84 storms compared with the 1981-2010 average of 89. Similar to 2010 and 2011, the North Atlantic was the only hurricane basin that experienced above-normal activity. In this basin, Sandy brought devastation to Cuba and parts of the eastern North American seaboard. All other basins experienced either near-or below-normal tropical cyclone activity. Only three tropical cyclones reached Category 5 intensity-all in Bopha became the only storm in the historical record to produce winds greater than 130 kt south of 7 N. It was also the costliest storm to affect the Philippines and killed more than 1000 residents. Minimum Arctic sea ice extent in September and Northern Hemisphere snow cover extent in June both reached new record lows. June snow cover extent is now declining at a faster rate (-17.6% per decade) than September sea ice extent (-13.0% per decade). Permafrost temperatures reached record high values in northernmost Alaska. A new melt extent record occurred on 11-12 July on the Greenland ice sheet; 97% of the ice sheet showed some form of melt, four times greater than the average melt for this time of year. The climate in Antarctica was relatively stable overall. The largest maximum sea ice extent since records begain in 1978 was observed in September 2012. In the stratosphere, warm air led to the second smallest ozone hole in the past two decades. Even so, the springtime ozone layer above Antarctica likely will not return to its early 1980s state until about 2060. Following a slight decline associated with the global 2 emissions from fossil fuel combustion and cement production reached a record 9.5 +/- 0.5 Pg C in 2011 and a new record of 9.7 +/- 0.5 Pg C is estimated for 2012. Atmospheric CO2 concentrations increased by 2.1 ppm in 2012, to 392.6 ppm. In spring 2012, 2 concentration exceeded 400 ppm at 7 of the 13 Arctic observation sites. Globally, other greenhouse gases including methane and nitrous oxide also continued to rise in concentration and the combined effect now represents a 32% increase in radiative forcing over a 1990 baseline. Concentrations of most ozone depleting substances continued to fall.
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| 7. |
- Bridel, Claire, et al.
(författare)
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Diagnostic Value of Cerebrospinal Fluid Neurofilament Light Protein in Neurology : A Systematic Review and Meta-analysis
- 2019
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Ingår i: JAMA Neurology. - : American Medical Association (AMA). - 2168-6149 .- 2168-6157. ; 76:9, s. 1035-1048
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Forskningsöversikt (refereegranskat)abstract
- Importance Neurofilament light protein (NfL) is elevated in cerebrospinal fluid (CSF) of a number of neurological conditions compared with healthy controls (HC) and is a candidate biomarker for neuroaxonal damage. The influence of age and sex is largely unknown, and levels across neurological disorders have not been compared systematically to date.Objectives To assess the associations of age, sex, and diagnosis with NfL in CSF (cNfL) and to evaluate its potential in discriminating clinically similar conditions.Data Sources PubMed was searched for studies published between January 1, 2006, and January 1, 2016, reporting cNfL levels (using the search terms neurofilament light and cerebrospinal fluid) in neurological or psychiatric conditions and/or in HC.Study Selection Studies reporting NfL levels measured in lumbar CSF using a commercially available immunoassay, as well as age and sex.Data Extraction and Synthesis Individual-level data were requested from study authors. Generalized linear mixed-effects models were used to estimate the fixed effects of age, sex, and diagnosis on log-transformed NfL levels, with cohort of origin modeled as a random intercept.Main Outcome and Measure The cNfL levels adjusted for age and sex across diagnoses.Results Data were collected for 10 059 individuals (mean [SD] age, 59.7 [18.8] years; 54.1% female). Thirty-five diagnoses were identified, including inflammatory diseases of the central nervous system (n = 2795), dementias and predementia stages (n = 4284), parkinsonian disorders (n = 984), and HC (n = 1332). The cNfL was elevated compared with HC in a majority of neurological conditions studied. Highest levels were observed in cognitively impaired HIV-positive individuals (iHIV), amyotrophic lateral sclerosis, frontotemporal dementia (FTD), and Huntington disease. In 33.3% of diagnoses, including HC, multiple sclerosis, Alzheimer disease (AD), and Parkinson disease (PD), cNfL was higher in men than women. The cNfL increased with age in HC and a majority of neurological conditions, although the association was strongest in HC. The cNfL overlapped in most clinically similar diagnoses except for FTD and iHIV, which segregated from other dementias, and PD, which segregated from atypical parkinsonian syndromes.Conclusions and Relevance These data support the use of cNfL as a biomarker of neuroaxonal damage and indicate that age-specific and sex-specific (and in some cases disease-specific) reference values may be needed. The cNfL has potential to assist the differentiation of FTD from AD and PD from atypical parkinsonian syndromes.
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| 8. |
- Hell, Benjamin, 1977-, et al.
(författare)
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The use of bathymetric data in society and science : A review from the Baltic Sea
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Tidskriftsartikel (refereegranskat)abstract
- Bathymetry, the underwater topography, is a fundamental property of oceans, seas and lakes. As such it is important for a wide range of applications, like physical oceanography, marine geology, geophysics and biology or the administration of marine resources. The exact requirements users may have regarding bathymetric data are, however, unclear. Here, the results of a questionnaire survey and a literature review are presented, concerning the use of Baltic Sea bathymetric data in research and for societal needs. It is demonstrated that there is a great need for detailed bathymetric data, which cannot be satisfied by the digital bathymetric models publicly available, despite of the abundance of high quality bathymetric data that are produced for safety of navigation purposes. Our study shows that DBMs based on such data could substantially improve the base data for administrative decision making as well as the possibilities for marine research in the Baltic Sea.
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| 9. |
- Hell, Benjamin, 1977-, et al.
(författare)
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The Use of Bathymetric Data in Society and Science : A Review from the Baltic Sea
- 2012
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 41:2, s. 138-150
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Forskningsöversikt (refereegranskat)abstract
- Bathymetry, the underwater topography, is a fundamental property of oceans, seas, and lakes. As such it is important for a wide range of applications, like physical oceanography, marine geology, geophysics and biology or the administration of marine resources. The exact requirements users may have regarding bathymetric data are, however, unclear. Here, the results of a questionnaire survey and a literature review are presented, concerning the use of Baltic Sea bathymetric data in research and for societal needs. It is demonstrated that there is a great need for detailed bathymetric data. Despite the abundance of high-quality bathymetric data that are produced for safety of navigation purposes, the digital bathymetric models publicly available to date cannot satisfy this need. Our study shows that DBMs based on data collected for safety of navigation could substantially improve the base data for administrative decision making as well as the possibilities for marine research in the Baltic Sea.
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| 10. |
- Jakobsson, Martin, et al.
(författare)
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The Early Miocene Onset of a Ventilated Circulation Regime in the Arctic Ocean
- 2007
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 447:7147, s. 986-990
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Tidskriftsartikel (refereegranskat)abstract
- Deep-water formation in the northern North Atlantic Ocean and the Arctic Ocean is a key driver of the global thermohaline circulation and hence also of global climate. Deciphering the history of the circulation regime in the Arctic Ocean has long been prevented by the lack of data from cores of Cenozoic sediments from the Arctic’s deep-sea floor. Similarly, the timing of the opening of a connection between the northern North Atlantic and the Arctic Ocean, permitting deep-water exchange, has been poorly constrained. This situation changed when the first drill cores were recovered from the central Arctic Ocean. Here we use these cores to show that the transition from poorly oxygenated to fully oxygenated (‘ventilated’) conditions in the Arctic Ocean occurred during the later part of early Miocene times. We attribute this pronounced change in ventilation regime to the opening of the Fram Strait. A palaeo-geographic and palaeo-bathymetric reconstruction of the Arctic Ocean, together with a physical oceanographic analysis of the evolving strait and sill conditions in the Fram Strait, suggests that the Arctic Ocean went from an oxygenpoor ‘lake stage’, to a transitional ‘estuarine sea’ phase with variable ventilation, and finally to the fully ventilated ‘ocean’ phase 17.5 Myr ago. The timing of this palaeo-oceanographic change coincides with the onset of the middle Miocene climatic optimum, although it remains unclear if there is a causal relationship between these two events.
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| 11. |
- Lachner, Johannes, et al.
(författare)
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Carrier free Be-10/Be-9 measurements with low-energy AMS : Determination of sedimentation rates in the Arctic Ocean
- 2013
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 294, s. 67-71
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Tidskriftsartikel (refereegranskat)abstract
- Using the TANDY AMS facility (600 kV) at ETH Zurich the seawater-derived (authigenic) Be-10/Be-9 ratio of marine sediment samples is measured without the addition of Be-9 carrier. This novel method reduces systematic uncertainties because the Be-10/Be-9 ratio of a sample is determined in only one (AMS) measurement. A challenge of carrier-free AMS is to avoid any contamination of the sample with Be-9 during the chemical preparation. Further, the leaching procedure has to be reproducible and ideally should attack the authigenic Be of the sediments only, leaving the detrital Be untouched. The low amount of stable Be-9 in the unspiked samples causes low currents during the AMS measurement. This requires a good stability and sensitivity of the AMS setup. Our first results show that the new preparation method is reliable and that background from stable Be-9 is avoided.For a comparison study, sediment samples from two cores located in the Arctic Ocean (HLY0503-09JPC, HLY0503-14JPC) were used. The authigenic Be-10/Be-9 ratio of these samples had been determined previously applying the conventional method where Be-10 and Be-9 concentrations are measured separately by AMS and ICP-MS, respectively. The resulting sedimentation rates are in discrepancy with values derived from biomarkers. To cross check the Be-10/Be-9 based age model two samples from each core were measured again with the new carrier-free method. The carrier-free results show systematically higher authigenic Be-10/Be-9 ratios. The calculated sedimentation rates of about 0.2 cm/kyr, however, are consistent for the carrier free and the conventional method.
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| 12. |
- Martens, Jannik, et al.
(författare)
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Remobilization of Old Permafrost Carbon to Chukchi Sea Sediments During the End of the Last Deglaciation
- 2019
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Ingår i: Global Biogeochemical Cycles. - 0886-6236 .- 1944-9224. ; 33:1, s. 2-14
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Tidskriftsartikel (refereegranskat)abstract
- Climate warming is expected to destabilize permafrost carbon (PF-C) by thaw-erosion and deepening of the seasonally thawed active layer and thereby promote PF-C mineralization to CO2 and CH4. A similar PF-C remobilization might have contributed to the increase in atmospheric CO2 during deglacial warming after the last glacial maximum. Using carbon isotopes and terrestrial biomarkers (Delta C-14, delta C-13, and lignin phenols), this study quantifies deposition of terrestrial carbon originating from permafrost in sediments from the Chukchi Sea (core SWERUS-L2-4-PC1). The sediment core reconstructs remobilization of permafrost carbon during the late Allerod warm period starting at 13,000 cal years before present (BP), the Younger Dryas, and the early Holocene warming until 11,000 cal years BP and compares this period with the late Holocene, from 3,650 years BP until present. Dual-carbon-isotope-based source apportionment demonstrates that Ice Complex Deposit-ice- and carbon-rich permafrost from the late Pleistocene (also referred to as Yedoma)-was the dominant source of organic carbon (66 +/- 8%; mean +/- standard deviation) to sediments during the end of the deglaciation, with fluxes more than twice as high (8.0 +/- 4.6 g.m(-2).year(-1)) as in the late Holocene (3.1 +/- 1.0 g.m(-2).year(-1)). These results are consistent with late deglacial PF-C remobilization observed in a Laptev Sea record, yet in contrast with PF-C sources, which at that location were dominated by active layer material from the Lena River watershed. Release of dormant PF-C from erosion of coastal permafrost during the end of the last deglaciation indicates vulnerability of Ice Complex Deposit in response to future warming and sea level changes.
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| 13. |
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| 14. |
- Modig, Niclas, 1973-
(författare)
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Hur kan ekonomi göras begripligt? : En studie om villkor för kraftfull ekonomiundervisning i samhällskunskap
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis seeks to understand what constitutes important economics knowledge from a disciplinary perspective and how such knowledge is recontextualized in textbooks and teacher training to become teachable to social studies students in Sweden’s upper secondary schools. It consists of four substudies: two covering disciplinary economics knowledge and two covering preservice social studies teachers. The first and second substudies focus on disciplinary economics knowledge. The first substudy, which was based on an online questionnaire for Swedish economics scholars at higher education institutions, shows that six economics terms/principles are especially important for people to understand. Such knowledge may be considered powerful economics knowledge. The second substudy demonstrates that there are great variations in the extent to which powerful economics terms appear in Swedish social studies textbooks and in how the language used shifts between everyday and scientific language. There is a risk that not all learners are given equal preconditions to develop economics knowledge through social studies textbooks. The third and fourth substudies focus on how preservice social studies teachers develop the ability to teach economic knowledge and show that students’ individual pedagogical content knowledge (PCK) depends on theoretical and practical studies. Students are unconfident about their economics knowledge, which may negatively affect their willingness and ability to teach economics when they become in-service social studies teachers.Overall, there appears to be a problem with the recontextualization of economics knowledge in Swedish social studies textbooks and with economics education for preservice social studies teachers. This may negatively affect economics education. As a result, it is important to strengthen preservice social studies teachers’ economics knowledge through increased economics content during teacher training. The importance of imparting powerful economics knowledge and shifting between everyday and scientific language in textbooks and during teaching needs to be highlighted for policymakers, textbook authors, and teacher educators.
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| 15. |
- Möller, Per, et al.
(författare)
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Deglaciation history and subsequent lake dynamics in the Siljan region, south-central Sweden, based on new LiDAR evidence and sediment records
- 2022
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Ingår i: Earth Surface Processes and Landforms. - : Wiley. - 0197-9337 .- 1096-9837. ; 47, s. 3515-3545
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Tidskriftsartikel (refereegranskat)abstract
- The Siljan region hosts Europe´s largest impact structure. The high-relief landscape, with a central granite dome bordered by lake basins, contains an array of glacial and shore-level landforms. We investigated its deglaciation history by mapping and analysing landforms on high resolution LiDAR-based Digital Surface Models coupled with well-dated sediment successions from peat and lake sediment cores. The granite dome and bordering areas are characterized by streamlined terrain and ribbed moraine with a streamlined overprint. These suggest an ice-flow direction from NNW with wet-based thermal conditions prior to deglaciation. During its retreat, the ice sheet was split into thinner plateau ice and thicker basin ice. Sets of low-gradient glaciofluvial erosion channels suggest intense ice-lateral meltwater drainage across gradually ice-freed slopes, while 'down-the-slope' erosion channels and eskers show meltwater drainage from stagnated plateau ice. Thick basin ice receded with a subaqueous margin across the deep Siljan–Orsasjön Basin c. 10,700–10,500 cal. BP. During ice recession the ingression of the Baltic Ancylus Lake led to diachronous formation of highest shoreline marks, from c. 207 m in the south to c. 220 m a.s.l. in the north. Differential uplift resulted in shallowing of the water body, which led to the isolation of the Siljan–Orsasjön Basin from the Baltic Basin at c. 9800 cal. BP. The post-isolation water body – the ‘Ancient Lake Siljan' – was drained through the ancient Åkerö Channel with a water level at 168–169 m a.s.l. during c. 1000 years. A later rerouting of the outlet to the present course was initiated at c. 8800 cal. BP, which led to a lake-level lowering of 6–7 m to today’s level of Lake Siljan (c. 162 m a.s.l.). This study shows the strength of an integrated methodological approach for deciphering the evolution of a complex landscape, combining highly resolved geomorphological analysis with well-dated sediment successions.
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| 16. |
- Möller, Per, et al.
(författare)
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Deglaciation history and subsequent lake dynamics in the Siljan region, south-central Sweden - LiDAR evidence and sediment records
- 2024
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The Siljan region hosts Europe´s largest impact structure. The high-relief landscape, with a central granite dome bordered by lake basins, contains an array of glacial and shore-level landforms. We investigated its deglaciation history by mapping and analysing landforms on high resolution LiDAR-based Digital Surface Models coupled with well-dated sediment successions from peat and lake sediment cores. The granite dome and bordering areas are characterized by streamlined terrain and ribbed moraine with a streamlined overprint. These suggest an ice-flow direction from NNW with wet-based thermal conditions prior to deglaciation. During its retreat, the ice sheet was split into thinner plateau ice and thicker basin ice. Sets of low-gradient glaciofluvial erosion channels suggest intense ice-lateral meltwater drainage across gradually ice-freed slopes, while 'down-the-slope' erosion channels and eskers show meltwater drainage from stagnated plateau ice. Thick basin ice receded with a subaqueous margin across the deep Siljan–Orsasjön Basin c. 10,700–10,500 cal. BP. During ice recession the ingression of the Baltic Ancylus Lake led to diachronous formation of highest shoreline marks, from 207 m in the south to 220 m a.s.l. in the north. Differential uplift resulted in shallowing of the water body, which led to the isolation of the Siljan¬–Orsasjön Basin from the Baltic Basin at c. 9800 cal. BP. The post-isolation water body – the ‘Ancient Lake Siljan' – was drained through the ancient Åkerö Channel with a water level at 168–169 m a.s.l. during c. 1000 years. A later rerouting of the outlet to the present course was initiated at c. 8800 cal. BP, which led to a lake-level lowering of 6–7 m to today’s level of Lake Siljan (162 m a.s.l.). This study shows the strength of an integrated methodological approach for deciphering the evolution of a complex landscape, combining highly resolved geomorphological analysis with well-dated sediment successions.
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| 17. |
- O'Regan, Matthew, et al.
(författare)
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Plio-Pleistocene trends in ice rafted debris on the Lomonosov Ridge
- 2010
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Ingår i: Quaternary International. - : Elsevier BV. - 1040-6182 .- 1873-4553. ; 19:1-2, s. 168-176
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Tidskriftsartikel (refereegranskat)abstract
- Although more than 700 sediment cores exist from the Arctic Ocean, the Plio-Pleistocene evolution of the basin and its marginal seas remains virtually unknown. This is largely due the shallow penetration of most of these records, and difficulties associated with deriving chronologies for the recovered material. The Integrated Ocean Drilling Program's (IODP) Expedition 302 (Arctic Coring Expedition, ACEX) recovered 197 m of Neogene/Quaternary sediment from the circumpolar regions of the Lomonosov Ridge. As detailed analyses of this material emerge, research is beginning to formulate a long-term picture of paleoceanographic changes in the central Arctic Ocean. This paper reviews the ACEX Plio-Pleistocene age model, identifies uncertainties, and addresses ways in which these may be eliminated. Within the established stratigraphic framework, a notable reduction in the abundance of ice rafted debris (IRD) occurs in the early part of the Pleistocene and persists until Marine Isotope Stage 6 (MIS 6). Therefore, while global oceanographic proxies indicate the gradual growth of terrestrial ice-sheets during this time, IRD delivery to the central Arctic Ocean remained comparatively low and stable. Within the resolution of existing data, the Pleistocene reduction in IRD is synchronous with predicted changes in both the inflow of North Atlantic and Pacific waters, which in modern times are known to exert a strong influence on sea ice stability.
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| 18. |
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| 19. |
- Sellén, Emma, et al.
(författare)
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Beryllium Isotope Dating of Sediment Cores From the Alpha Ridge, Arctic Ocean
- 2007
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Ingår i: Eos, Trans. AGU, 88(52), Fall Meeting.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- AB: Poor preservation of biogenic calcium carbonate and biosilica in Arctic Ocean sediments has led to large problems regarding the establishment of a reliable chronostratigraphy. There are currently two differing sedimentation rate scenarios proposed for the Arctic Ocean. The first suggests sedimentation rates on the order of mm/ka and is based on cores from the Amerasian Basin, whereas the second suggests sedimentation rates on the order of cm/ka mainly derived from Eurasian Basin cores. Here we present dating results from cores HLY0503-09JPC and HLY0503-14JPC retrieved from the Alpha Ridge during the Healy-Oden Trans-Arctic Expedition 2005 (HOTRAX). These cores have been analyzed for seawater-derived beryllium (Be) isotopes in order to establish a chronostratigraphy. The isotopes 10Be and 9Be were extracted simultaneously from sample aliquots by using a leaching procedure. The decrease of 10Be concentration (half-life = 1.51 Million years) with depth in core provides first order sedimentation rates for the sampled cores. To eliminate the dilution effect of beryllium caused by short-term changes in sedimentation rate and grain size variability, the 10Be concentration was normalized to the stable isotope 9Be. The preliminary results show low downcore 10Be concentrations in both cores from the Alpha Ridge. Plotting 10Be against depth suggests an average sedimentation rate of ~2.9 mm/ka for core HLY0503-09JPC and ~2.3 mm/ka for HLY0503- 14JPC. The calculated 10Be/9Be ratios point to even lower average sedimentation rates of ~1.9 mm/ka for core HLY0503-09JPC and ~1.6 mm/ka for HLY0503-14JPC. However, core HLY0503-14JPC shows a pronounced variability of the 10Be concentration as well as for the 10Be/9Be ratio, which results in a large uncertainty of the calculated sedimentation rates. The 10Be concentrations for this core will be compared with the grain size record in order to reduce the scatter of the data. The preliminary beryllium isotope chronostratigraphy supports lower sedimentation rates in the Amerasian Basin compared to the Eurasian Basin. A long-term solid sea ice cover in the Beaufort Gyre may explain the low 10Be concentrations, but does not explain the calculated low sedimentation rates.
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| 20. |
- Sellén, Emma, et al.
(författare)
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Beryllium isotope variations in sediment cores from the Alpha Ridge, Arctic Ocean
- 2008
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Ingår i: Arctic Palaeoclimate and its Extremes (APEX). ; , s. 92-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The Healy-Oden Trans-Arctic Expedition 2005 (HOTRAX) recovered cores along a transect across the Arctic Ocean. Here we present results from measurements of seawater-derived beryllium isotopes in cores HLY0503-09JPC and HLY0503-14JPC from the Alpha-Mendeleev Ridge. The intention of measuring beryllium (Be) isotopes is to establish a chronostratigraphy as the decrease of 10Be concentration (half-life = 1.51 Million years) with depth in the cores may provide first order sedimentation rates. The isotopes 10Be and 9Be were extracted simultaneously from sample aliquots by using a leaching procedure. To eliminate the dilution effect of beryllium caused by short-term changes in sedimentation rate and grain size variability, the 10Be concentration was normalized to the stable isotope 9Be. The results show low downcore 10Be concentrations and subsequently sedimentation rates on the order of mm/ka in both cores from the Alpha Ridge. However, we note two indications suggesting that our calculated sedimentation rates from the beryllium results may not be valid and requires further analysis: 1) the decrease of 10Be down core does not follow a well defined trend; 2) a comparison with preliminary results from nannofossil studies of cores HLY0503-14JPC and HLY0503-08JPC located nearby HLY0503-09JPC indicates much higher sedimentation rates than we obtained from the 10Be data (Backman and Fornaciari pers. comm.). The pronounced decrease of 10Be with core depth may imply a stronger effect of sea ice shielding of atmospheric inputs, whereas the 9Be increase with depth may point to a stronger continental input of 9Be.
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| 21. |
- Sellén, Emma, et al.
(författare)
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Pleistocene variations of beryllium isotopes in central Arctic Ocean sediment cores
- 2009
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Ingår i: Global and Planetary Change. - : Elsevier BV. - 0921-8181 .- 1872-6364. ; 68:1-2, s. 38-47
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Tidskriftsartikel (refereegranskat)abstract
- Neogene marine sediments can be dated via decay of the cosmogenic radionuclide 10Be. Two cores from theAlpha and Mendeleev Ridges in the Arctic Ocean have been analyzed for seawater-derived beryllium (Be)isotopes in order to date the sediments and to calculate sedimentation rates. The decrease of 10Be concentrationin the cores was used to calculate first order sedimentation rates. To eliminate the dilution effect of berylliumcaused by short-term changes in sedimentation rate and grain size, the 10Be concentrationswere normalized tothe terrigenous stable isotope 9Be determined in the same sample aliquot. The measured 10Be concentrationsyield low average sedimentation rates for the Alpha and Mendeleev Ridges of 2.3 mm ka−1 and 2.7 mm ka−1,respectively. Sedimentation rates calculated from the 10Be/9Be ratios result in similarly low values, rangingfrom 0.2 to 6.8 mm ka−1 for the Alpha Ridge core and from 1.9 to 6.9 mm ka−1 for the Mendeleev Ridge core.However, amino acid racemization dating for the past 150 ka of a core adjacent to the Mendeleev Ridge corestudied here indicates significantly higher sedimentation rates than calculated from the downcore decreaseof 10Be and 10Be/9Be. If such higher rates also prevailed at the locations of our cores, for which there isbiostratigraphic evidence, either the supply of 10Be was much lower than assumed or that of 9Be was muchhigher. This could imply that the signature of the deepwaters in this part of the Arctic Ocean compared to todaywas largely different for most of the past approximately one million years with a significantly lower 10Be/9Beratio. Our study also addresses the variability of beryllium isotopes in sediment cores across the Arctic Oceanthrough a comparison of previously published results. Calculated 10Be fluxes reveal low values in the AmerasianBasin and highest values in the Eurasian Basin, near the Fram Strait. The decrease of Be isotopes in the twostudied Amerasian Basin cores may thus have been caused by environmental factors such as significantlyreduced inflow of Atlantic waters in the past, reduced input of 10Be and/or increased input of 9Be from theshelves, combined with a more efficient sea ice shielding in this part of the Arctic Ocean.
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| 22. |
- Stokes, Chris R., et al.
(författare)
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On the reconstruction of palaeo-ice sheets : Recent advances and future challenges
- 2015
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 125, s. 15-49
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Forskningsöversikt (refereegranskat)abstract
- Reconstructing the growth and decay of palaeo-ice sheets is critical to understanding mechanisms of global climate change and associated sea-level fluctuations in the past, present and future. The significance of palaeo-ice sheets is further underlined by the broad range of disciplines concerned with reconstructing their behaviour, many of which have undergone a rapid expansion since the 1980s. In particular, there has been a major increase in the size and qualitative diversity of empirical data used to reconstruct and date ice sheets, and major improvements in our ability to simulate their dynamics in numerical ice sheet models. These developments have made it increasingly necessary to forge interdisciplinary links between sub-disciplines and to link numerical modelling with observations and dating of proxy records. The aim of this paper is to evaluate recent developments in the methods used to reconstruct ice sheets and outline some key challenges that remain, with an emphasis on how future work might integrate terrestrial and marine evidence together with numerical modelling. Our focus is on pan-ice sheet reconstructions of the last deglaciation, but regional case studies are used to illustrate methodological achievements, challenges and opportunities. Whilst various disciplines have made important progress in our understanding of ice-sheet dynamics, it is clear that data-model integration remains under-used, and that uncertainties remain poorly quantified in both empirically-based and numerical ice-Sheet reconstructions. The representation of past climate will continue to be the largest source of uncertainty for numerical modelling. As such, palaeo-observations are critical to constrain and validate modelling. State-of-the-art numerical models will continue to improve both in model resolution and in the breadth of inclusion of relevant processes, thereby enabling more accurate and more direct comparison with the increasing range of palaeo-observations. Thus, the capability is developing to use all relevant palaeo-records to more strongly constrain deglacial (and to a lesser extent pre-LGM) ice sheet evolution. In working towards that goal, the accurate representation of uncertainties is required for both constraint data and model outputs. Close cooperation between modelling and data-gathering communities is essential to ensure this capability is realised and continues to progress.
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| 23. |
- Thorén, Anna, et al.
(författare)
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Rapid response team activation prior to in-hospital cardiac arrest: Areas for improvements based on a national cohort study
- 2023
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Ingår i: Resuscitation. - 0300-9572 .- 1873-1570. ; 193
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Rapid response teams (RRTs) are designed to improve the "chain of prevention" of in-hospital cardiac arrest (IHCA). We studied the 30-day survival of patients reviewed by RRTs within 24 hours prior to IHCA, as compared to patients not reviewed by RRTs.Methods: A nationwide cohort study based on the Swedish Registry of Cardiopulmonary Resuscitation, between January 1st, 2014, and December 31st, 2021. An explorative, hypothesis-generating additional in-depth data collection from medical records was performed in a small subgroup of general ward patients reviewed by RRTs.Results: In all, 12,915 IHCA patients were included. RRT-reviewed patients (n = 2,058) had a lower unadjusted 30-day survival (25% vs 33%, p < 0.001), a propensity score based Odds ratio for 30-day survival of 0.92 (95% Confidence interval 0.90-0.94, p < 0.001) and were more likely to have a respiratory cause of IHCA (22% vs 15%, p < 0.001). In the subgroup (n = 82), respiratory distress was the most common RRT trigger, and 24% of the RRT reviews were delayed. Patient transfer to a higher level of care was associated with a higher 30-day survival rate (20% vs 2%, p < 0.001).Conclusion: IHCA preceded by RRT review is associated with a lower 30-day survival rate and a greater likelihood of a respiratory cause of cardiac arrest. In the small explorative subgroup, respiratory distress was the most common RRT trigger and delayed RRT activation was frequent. Early detection of respiratory abnormalities and timely interventions may have a potential to improve outcomes in RRT-reviewed patients and prevent further progress into IHCA.
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| 24. |
- Tondel, Martin, et al.
(författare)
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Incidence of neoplasms in ages 0-19 y in parts of Sweden with high 137Cs fallout after the Chernobyl accident
- 1996
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Ingår i: Health Physics. - 0017-9078 .- 1538-5159. ; 71:6, s. 947-950
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Tidskriftsartikel (refereegranskat)abstract
- The incidence of neoplasms in childhood and adolescence in northern and central Sweden before and after the radioactive fallout from the Chernobyl accident was investigated in an ecologic study, 1978 to 1992. The study included all parishes in the six most contaminated counties classified after aerial mapping of ground radiation from 137Cs and investigated 746 cases of neoplasms in ages 0-19 y, diagnosed in the six counties. Incidence and relative risks of neoplasms were compared in areas with high, intermediate, and low contamination after versus before the Chernobyl accident in 1986. A continuous increase of brain tumor incidence in the ages 0-19 y during the period 1978-92 without clear relationship to the Chernobyl fallout was discovered. No clear relationship between the incidence of brain tumor and the exposure to varying levels of radiation from 137Cs was apparent. A somewhat decreased relative risk of acute lymphatic leukemia appeared in areas with increased exposure. Other neoplasms showed no changes in incidence over time or with regard to exposure. Until now, there is no indication that the Chernobyl accident has affected the incidence of childhood and adolescence neoplasms in Sweden, but it is still too early for any final conclusion about the effect of this event.
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| 25. |
- Wölfl, Anne-Cathrin, et al.
(författare)
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Seafloor Mapping - The Challenge of a Truly Global Ocean Bathymetry
- 2019
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Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 6
-
Forskningsöversikt (refereegranskat)abstract
- Detailed knowledge of the shape of the seafloor is crucial to humankind. Bathymetry data is critical for safety of navigation and is used for many other applications. In an era of ongoing environmental degradation worldwide, bathymetry data (and the knowledge derived from it) play a pivotal role in using and managing the world's oceans in a way that is in accordance with the United Nations Sustainable Development Goal 14 - conserve and sustainably use the oceans, seas and marine resources for sustainable development. However, the vast majority of our oceans is still virtually unmapped, unobserved, and unexplored. Only a small fraction of the seafloor has been systematically mapped by direct measurement. The remaining bathymetry is predicted from satellite altimeter data, providing only an approximate estimation of the shape of the seafloor. Several global and regional initiatives are underway to change this situation. This paper presents a selection of these initiatives as best practice examples for bathymetry data collection, compilation and open data sharing as well as the Nippon Foundation-GEBCO (The General Bathymetric Chart of the Oceans) Seabed 2030 Project that complements and leverages these initiatives and promotes international collaboration and partnership. Several non-traditional data collection opportunities are looked at that are currently gaining momentum as well as new and innovative technologies that can increase the efficiency of collecting bathymetric data. Finally, recommendations are given toward a possible way forward into the future of seafloor mapping and toward achieving the goal of a truly global ocean bathymetry.
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| 26. |
- Alexanderson, Helena, et al.
(författare)
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An Arctic perspective on dating Mid-Late Pleistocene environmental history
- 2014
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 92, s. 9-31
-
Forskningsöversikt (refereegranskat)abstract
- To better understand Pleistocene climatic changes in the Arctic, integrated palaeoenvironmental andpalaeoclimatic signals from a variety of marine and terrestrial geological records as well as geochronologicage control are required, not least for correlation to extra-Arctic records. In this paper we discuss,from an Arctic perspective, methods and correlation tools that are commonly used to date ArcticPleistocene marine and terrestrial events. We review the state of the art of Arctic geochronology, withfocus on factors that affect the possibility and quality of dating, and support this overview by examples ofapplication of modern dating methods to Arctic terrestrial and marine sequences.Event stratigraphy and numerical ages are important tools used in the Arctic to correlate fragmentedterrestrial records and to establish regional stratigraphic schemes. Age control is commonly provided byradiocarbon, luminescence or cosmogenic exposure ages. Arctic Ocean deep-sea sediment successionscan be correlated over large distances based on geochemical and physical property proxies for sedimentcomposition, patterns in palaeomagnetic records and, increasingly, biostratigraphic data. Many of theseproxies reveal cyclical patterns that provide a basis for astronomical tuning.Recent advances in dating technology, calibration and age modelling allow for measuring smallerquantities of material and to more precisely date previously undatable material (i.e. foraminifera for 14C,and single-grain luminescence). However, for much of the Pleistocene there are still limits to the resolutionof most dating methods. Consequently improving the accuracy and precision (analytical andgeological uncertainty) of dating methods through technological advances and better understanding ofprocesses are important tasks for the future. Another challenge is to better integrate marine andterrestrial records, which could be aided by targeting continental shelf and lake records, exploringproxies that occur in both settings, and by creating joint research networks that promote collaborationbetween marine and terrestrial geologists and modellers.
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| 27. |
- Alexandridis, Vasileios, et al.
(författare)
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Adjustable mini-sling compared with conventional mid-urethral slings in women with urinary incontinence : a 3-year follow-up of a randomized controlled trial
- 2019
-
Ingår i: International Urogynecology Journal. - : Springer Science and Business Media LLC. - 0937-3462 .- 1433-3023. ; 30:9, s. 1465-1473
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction and hypothesis: The aim of this study was to compare the long-term subjective outcomes of an adjustable single-incision sling (Ajust®) vs standard mid-urethral slings (SMUS) for the treatment of women with stress urinary incontinence. Methods: This study was designed as a multicenter prospective randomized trial. Women under 60 years old with objectively verified stress urinary incontinence were included from seven centers in three countries. Women with mixed urinary incontinence were also included. Randomization was held in blocks for operation with either Ajust® or SMUS. Women analyzed at 1-year follow-up received the International Consultation on Incontinence Questionnaire Urinary Incontinence Short Form (ICIQ-UI-SF), International Consultation on Incontinence Questionnaire Overactive Bladder, Pelvic Organ Prolapse/Urinary Incontinence/Sexual Function Questionnaire-12, Patient Global Impression of Severity, and Patient Global Impression of Improvement questionnaires, together with a bladder diary to fill out at least 3 years after the procedure. The main outcome evaluated was the subjective cure rate as reported through the ICIQ-UI-SF questionnaire at 3 years. Results: In total, 205 women participated in the 3-year follow-up: 107 in the Ajust® and 98 in the SMUS group. No significant difference was observed between the groups regarding subjective cure rate (50.9% vs 51.5%, p = 0.909) or dyspareunia. Both groups demonstrated similar postoperative perception of improvement in addition to reduced urgency and urge urinary incontinence. The postoperative improvement remained at the same level after 3 years as it was at 1-year follow-up for both Ajust® and SMUS. Conclusions: Ajust® appears to be equally effective and safe as SMUS with regard to long-term follow-up of patient-reported outcomes.
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| 28. |
- Altstadt, S.G., et al.
(författare)
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B-13,B-14(n,gamma) via Coulomb Dissociation for Nucleosynthesis towards the r-Process
- 2014
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Ingår i: Nuclear Data Sheets. - : Elsevier BV. - 1095-9904 .- 0090-3752. ; 120, s. 197-200
-
Konferensbidrag (refereegranskat)abstract
- Radioactive beams of 14,15B produced by fragmentation of a primary 40Ar beam were directed onto a Pb target to investigate the neutron breakup within the Coulomb field. The experiment was performed at the LAND/R3B setup. Preliminary results for the Coulomb dissociation cross sections as well as for the astrophysically interesting inverse reactions, 13,14B(n,γ), are presented.
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| 29. |
- An, Lu, et al.
(författare)
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Bathymetry of Southeast Greenland From Oceans Melting Greenland (OMG) Data
- 2019
-
Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 46:11, s. 197-205
-
Tidskriftsartikel (refereegranskat)abstract
- Southeast Greenland has been a major participant in the ice sheet mass loss over the last several decades. Interpreting the evolution of glacier fronts requires information about their depth below sea level and ocean thermal forcing, which are incompletely known in the region. Here, we combine airborne gravity and multibeam echo sounding data from the National Aeronautics and Space Administration's Oceans Melting Greenland (OMG) mission with ocean probe and fishing boat depth data to reconstruct the bathymetry extending from the glacier margins to the edges of the continental shelf. We perform a three-dimensional inversion of the gravity data over water and merge the solution with a mass conservation reconstruction of bed topography over land. In contrast with other parts of Greenland, we find few deep troughs connecting the glaciers to the sources of warm Atlantic Water, amidst a relatively uniform, shallow (350 m) continental shelf. The deep channels include the Kangerlugssuaq, Sermilik, Gyldenlove, and Tingmiarmiut Troughs.
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| 30. |
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| 31. |
- Anderson, John B., et al.
(författare)
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Geomorphic expression of collapsing ice streams revealed by latest generation swath bathymetry images
- 2011
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- There is now a substantial swath bathymetry data set from Antarctica that reveals subglacial bedforms, in particular mega-scale glacial lineations, which were formed by ice streams that occupied glacial troughs during the LGM. However, with the exception of grounding zone wedges, few studies have yielded high-resolution sea floor images that show geomorphic features formed by retreating ice streams. For example, deep-tow side-scan sonar records from Ross Sea show a range of recessional features, mostly 1-3 meters high, that overprint mega-scale glacial lineations. These features were not imaged in swath bathymetry records. During the 2010 austral summer, the Swedish ice breaker Oden was used to conduct an extensive survey in the sparsely studied central trough in Pine Island Bay using the latest generation multibeam technology. The bedforms imaged in Pine Island Bay are similar to small-scale recessional features previously imaged in Ross Sea using deep-tow side-scan sonar. These include fishbone moraines and corrugated iceberg furrows, which we argue were produced daily through tidally-influenced motion of a disintegrating ice shelf. During this event a 65 km long stretch of the trough was cleared of floating ice in about 1.5 years. The break-up occurred ~12,000 cal ka BP and was likely a response to rapid sea-level rise at that time. Acquisition of more high-resolution swath bathymetry data should greatly increase our understanding of ice stream interaction with the seafloor and those factors that have influenced ice stream behavior during retreat. Future work should focus on the rugged inner shelf, were subglacial meltwater is believed to have contributed to ice stream instability.
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| 32. |
- Anderson, John B., et al.
(författare)
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Ross Sea paleo-ice sheet drainage and deglacial history during and since the LGM
- 2014
-
Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 100, s. 31-54
-
Tidskriftsartikel (refereegranskat)abstract
- Onshore and offshore studies show that an expanded, grounded ice sheet occupied the Ross Sea Embayment during the Last Glacial Maximum (LGM). Results from studies of till provenance and the orientation of geomorphic features on the continental shelf show that more than half of the grounded ice sheet consisted of East Antarctic ice flowing through Transantarctic Mountain (TAM) outlet glaciers; the remainder came from West Antarctica. Terrestrial data indicate little or no thickening in the upper catchment regions in both West and East Antarctica during the LGM. In contrast, evidence from the mouths of the southern and central TAM outlet glaciers indicate surface elevations between 1000 m and 1100 m (above present-day sea level). Farther north along the western margin of the Ross Ice Sheet, surface elevations reached 720 m on Ross Island, and 400 m at Terra Nova Bay. Evidence from Marie Byrd Land at the eastern margin of the ice sheet indicates that the elevation near the present-day grounding line was more than 800 m asl, while at Siple Dome in the central Ross Embayment, the surface elevation was about 950 m asl. Farther north, evidence that the ice sheet was grounded on the middle and the outer continental shelf during the LGM implies that surface elevations had to be at least 100 m above the LGM sea level. The apparent low surface profile and implied low basal shear stress in the central and eastern embayment suggests that although the ice streams may have slowed during the LGM, they remained active. Ice-sheet retreat from the western Ross Embayment during the Holocene is constrained by marine and terrestrial data. Ages from marine sediments suggest that the grounding line had retreated from its LGM outer shelf location only a few tens of kilometer to a location south of Coulman Island by similar to 13 ka BP. The ice sheet margin was located in the vicinity of the Drygalski Ice Tongue by similar to 11 ka BP, just north of Ross Island by similar to 7.8 ka BP, and near Hatherton Glacier by similar to 6.8 ka BP. Farther south, Be-10 exposure ages from glacial erratics on nunataks near the mouths of Reedy, Scott and Beardmore Glaciers indicate thinning during the mid to late Holocene, but the grounding line did not reach its present position until 2 to 3 ka BP. Marine dates, which are almost exclusively Acid Insoluble Organic (AIO) dates, are consistently older than those derived from terrestrial data. However, even these ages indicate that the ice sheet experienced significant retreat after similar to 13 ka BP. Geomorphic features indicate that during the final stages of ice sheet retreat ice flowing through the TAM remained grounded on the shallow western margin of Ross Sea. The timing of retreat from the central Ross Sea remains unresolved; the simplest reconstruction is to assume that the grounding line here started to retreat from the continental shelf more or less in step with the retreat from the western and eastern sectors. An alternative hypothesis, which relies on the validity of radiocarbon ages from marine sediments, is that grounded ice had retreated from the outer continental shelf prior to the LGM. More reliable ages from marine sediments in the central Ross Embayment are needed to test and validate this hypothesis.
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| 33. |
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| 34. |
- Anderson, Leif G, 1951, et al.
(författare)
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Shelf-Basin interaction along the East Siberian Sea
- 2017
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Ingår i: Ocean Science. - : Copernicus GmbH. - 1812-0784 .- 1812-0792. ; 13:2, s. 349-363
-
Tidskriftsartikel (refereegranskat)abstract
- Extensive biogeochemical transformation of organic matter takes place in the shallow continental shelf seas of Siberia. This, in combination with brine production from sea-ice formation, results in cold bottom waters with relatively high salinity and nutrient concentrations, as well as low oxygen and pH levels. Data from the SWERUS-C3 expedition with icebreaker Oden, from July to September 2014, show the distribution of such nutrient-rich, cold bottom waters along the continental margin from about 140 to 180 degrees E. The water with maximum nutrient concentration, classically named the upper halocline, is absent over the Lomonosov Ridge at 140 degrees E, while it appears in the Makarov Basin at 150 degrees E and intensifies further eastwards. At the intercept between the Mendeleev Ridge and the East Siberian continental shelf slope, the nutrient maximum is still intense, but distributed across a larger depth interval. The nutrient-rich water is found here at salinities of up to similar to 34.5, i.e. in the water classically named lower halocline. East of 170 degrees E transient tracers show significantly less ventilated waters below about 150 m water depth. This likely results from a local isolation of waters over the Chukchi Abyssal Plain as the boundary current from the west is steered away from this area by the bathymetry of the Mendeleev Ridge. The water with salinities of similar to 34.5 has high nutrients and low oxygen concentrations as well as low pH, typically indicating decay of organic matter. A deficit in nitrate relative to phosphate suggests that this process partly occurs under hypoxia. We conclude that the high nutrient water with salinity similar to 34.5 are formed on the shelf slope in the Mendeleev Ridge region from interior basin water that is trapped for enough time to attain its signature through interaction with the sediment.
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| 35. |
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| 36. |
- Andersson, Axel G, et al.
(författare)
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High Exposure to Perfluoroalkyl Substances and Antibody Responses to SARS-CoV-2 mRNA Vaccine-an Observational Study in Adults from Ronneby, Sweden.
- 2023
-
Ingår i: Environmental health perspectives. - 1552-9924. ; 131:8
-
Tidskriftsartikel (refereegranskat)abstract
- Per- and polyfluoroalkyl substances (PFAS) are widely used, environmentally ubiquitous, and stable chemicals that have been associated with lower vaccine-induced antibody responses in children; however, data on adults are limited. The drinking water from one of the two waterworks in Ronneby, Sweden, was heavily contaminated for decades with PFAS from firefighting foams, primarily perfluorohexane sulfonic acid and perfluorooctanesulfonic acid (PFOS). Vaccination against SARS-CoV-2 offered a unique opportunity to investigate antibody responses to primary vaccination in adults who had been exposed to PFAS.Our objective was to evaluate associations between PFAS, across a wide range of exposure levels, and antibody responses in adults 5 wk and 6 months after a two-dose vaccination regime against SARS-CoV-2.Adults age 20-60 y from Ronneby (n=309, median PFOS serum level 47ng/mL, fifth to 95th percentile 4-213ng/mL) and a group with background exposure (n=47, median PFOS serum level 4ng/mL) received two doses of the Spikevax (Moderna) mRNA vaccine. The levels of seven PFAS were measured in serum before vaccination. Serum immunoglobulin G antibodies against the SARS-CoV-2 spike antigen (S-Abs) were measured before vaccination and at 5 wk (n=350) and 6 months (n=329) after the second vaccine dose. Linear regression analyses were fitted against current, historical, and prenatal exposure to PFAS, adjusting for sex, age, and smoking, excluding individuals with previous SARS-CoV-2-infection.PFAS exposure, regardless of how it was estimated, was not negatively associated with antibody levels 5 wk [current PFOS: -0.5% S-Abs/PFOS interquartile range (IQR); 95% confidence interval (CI): -8, 7] or 6 months (current PFOS: 3% S-Abs/PFOS IQR; 95% CI: -6, 12) after COVID-19 vaccination.Following a strict study protocol, rigorous study design, and few dropouts, we found no indication that PFAS exposure negatively affected antibody responses to COVID-19 mRNA vaccination for up to 6 months after vaccination. https://doi.org/10.1289/EHP11847.
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| 37. |
- Andersson, Rina Argelia, et al.
(författare)
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Organic matter delivery to Quaternary sediments of Amundsen Basin, central Arctic Ocean
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Quaternary marine sediments retrieved from the central Arctic Ocean in a 30 cm long core, were analyzed for paleoenvironmental reconstruction. n-Alkane biomarkers combined with elemental analyses that include X-ray fluorescence (XRF) core scanning provide complementary information that suggest important influxes of terrigenous derived organic matter (OM) with depth. Changes in the variability of n-alkane-derived and elemental ratios with depth reflect the complexity of the organic carbon cycle in this region. The distributions and abundances of the long-chain n-alkanes reveal a high content of terrigenous derived components and suggest together with mathematical estimations high deliveries of the terrigenous OM in the past. XRF trace metal analyses suggest less-oxygenated bottom waters that may have allowed for better preservation conditions of OM deeper in the core.
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| 38. |
- Andersson, Tommy, et al.
(författare)
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Bottom characterization of Lagoa das Furnas on Sao Miguel, Azores archipelago
- 2016
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Ingår i: Journal of Volcanology and Geothermal Research. - : Elsevier BV. - 0377-0273 .- 1872-6097. ; 321, s. 196-207
-
Tidskriftsartikel (refereegranskat)abstract
- Lagoa das Furnas is a crater lake located in an area exposed to geohazards from earthquakes and volcanic activity on the island of sao Miguel in the Azores Archipelago. Geophysical mapping of Lagoa das Furnas reveals a previously undiscovered volcanic dome. This dome is comprised largely of subaquatic pyroclastic debris of trachytic composition. Sedimentological, petrological, geochemical and geochronological studies of pyroclastic deposits from the dome link it to the historically documented Furnas 1630 eruption. The chemistry of glass and crystal fragments sampled from the dome suggests that it is comprised of more evolved magma than that of the main Furnas 1630 dome located 1400 m away. This suggests that the dome was formed during a final phase of the 1630 eruption in the Lagoa das Furnas area.
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| 39. |
- Andersson, Thommy
(författare)
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Geology of Lagoa das Furnas, a crater lake on São Miguel, Azores archipelago
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, the results from a geophysical mapping and coring campaign of Lagoa das Furnas are presented. Specific focus is placed on the origin of a subaqueous volcanic cone mapped in the southern part of the lake. Lagoa das Furnas is a crater lake within the Furnas volcanic centre which is located on the island of São Miguel in the Azores archipelago. The Furnas volcanic centre has a long history of earthquakes and volcanic activity. The area is relatively well-studied, except for the lake floor. Therefore, a high resolution geophysical and geological mapping survey was conducted at Lagoa das Furnas. Sidescan sonar was used to map the surface of the lake floor and single beam sonar was used to acquire sub-bottom profiles. In addition to the geophysical mapping, sediment surface sampling and core drilling were carried out followed by geochemical analyses of the retrieved material. The mapped data permitted a characterisation of the floor of Lagoa das Furnas and revealed several volcanic features including fumarole activity and a volcanic cone in the southern part of the lake. In order to unravel the origin of this cone several methods were applied, including analyses of tephra and minerals collected from the cone itself and from nearby deposits of two known eruptions Furnas I and Furnas 1630. Sedimentological, petrological, geochemical and geochronological studies of pyroclastic deposits from the cone suggest a subaqueous eruption linked to the Furnas 1630 eruption. The chemistry of glass and crystal fragments sampled from the cone suggests that it is composed of more evolved magma than that of the main Furnas 1630 implying that the lake cone is likely a product of the last eruptional phase. Historical documents reveal three lakes in Furnas valley before the 1630 eruption. Two of these lakes were lost due the eruption and the remaining lake is most likely Lagoa das Furnas and consequently did exist before the 1630 eruption.
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| 40. |
- Andrén, T., et al.
(författare)
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The Baltic Sea IODP project
- 2012
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Ingår i: EGU General Assembly Conference Abstracts. ; , s. 7682-7682
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 41. |
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| 42. |
- Arndt, Jan Erik, et al.
(författare)
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The International Bathymetric Chart of the Southern Ocean (IBCSO) Version 1.0-A new bathymetric compilation covering circum-Antarctic waters
- 2013
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Ingår i: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 40:12, s. 3111-3117
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Tidskriftsartikel (refereegranskat)abstract
- The International Bathymetric Chart of the Southern Ocean (IBCSO) Version 1.0 is a new digital bathymetric model (DBM) portraying the seafloor of the circum-Antarctic waters south of 60 degrees S. IBCSO is a regional mapping project of the General Bathymetric Chart of the Oceans (GEBCO). The IBCSO Version 1.0 DBM has been compiled from all available bathymetric data collectively gathered by more than 30 institutions from 15 countries. These data include multibeam and single-beam echo soundings, digitized depths from nautical charts, regional bathymetric gridded compilations, and predicted bathymetry. Specific gridding techniques were applied to compile the DBM from the bathymetric data of different origin, spatial distribution, resolution, and quality. The IBCSO Version 1.0 DBM has a resolution of 500 x 500 m, based on a polar stereographic projection, and is publicly available together with a digital chart for printing from the project website (www.ibcso.org) and at .
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| 43. |
- Auffret, Alistair G., et al.
(författare)
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More warm-adapted species in soil seed banks than in herb layer plant communities across Europe
- 2023
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Ingår i: Journal of Ecology. - : John Wiley & Sons. - 0022-0477 .- 1365-2745. ; 111:5, s. 1009-1020
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Tidskriftsartikel (refereegranskat)abstract
- Responses to climate change have often been found to lag behind the rate of warming that has occurred. In addition to dispersal limitation potentially restricting spread at leading range margins, the persistence of species in new and unsuitable conditions is thought to be responsible for apparent time-lags. Soil seed banks can allow plant communities to temporarily buffer unsuitable environmental conditions, but their potential to slow responses to long-term climate change is largely unknown. As local forest cover can also buffer the effects of a warming climate, it is important to understand how seed banks might interact with land cover to mediate community responses to climate change. We first related species-level seed bank persistence and distribution-derived climatic niches for 840 plant species. We then used a database of plant community data from grasslands, forests and intermediate successional habitats from across Europe to investigate relationships between seed banks and their corresponding herb layers in 2763 plots in the context of climate and land cover. We found that species from warmer climates and with broader distributions are more likely to have a higher seed bank persistence, resulting in seed banks that are composed of species with warmer and broader climatic distributions than their corresponding herb layers. This was consistent across our climatic extent, with larger differences (seed banks from even warmer climates relative to vegetation) found in grasslands. Synthesis. Seed banks have been shown to buffer plant communities through periods of environmental variability, and in a period of climate change might be expected to contain species reflecting past, cooler conditions. Here, we show that persistent seed banks often contain species with relatively warm climatic niches and those with wide climatic ranges. Although these patterns may not be primarily driven by species’ climatic adaptations, the prominence of such species in seed banks might still facilitate climate-driven community shifts. Additionally, seed banks may be related to ongoing trends regarding the spread of widespread generalist species into natural habitats, while cool-associated species may be at risk from both short- and long-term climatic variability and change.
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| 47. |
- Barrientos, Natalia, et al.
(författare)
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Arctic Ocean benthic foraminifera Mg/Ca ratios and global Mg/Ca-temperature calibrations: New constraints at low temperatures
- 2018
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Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier BV. - 0016-7037 .- 1872-9533. ; 236, s. 240-259
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Tidskriftsartikel (refereegranskat)abstract
- We explore the use of Mg/Ca ratios in six Arctic Ocean benthic foraminifera species as bottom water palaeothermometers and expand published Mg/Ca-temperature calibrations to the coldest bottom temperatures (<1 °C). Foraminifera were analyzed in surface sediments at 27 sites in the Chukchi Sea, East Siberian Sea, Laptev Sea, Lomonosov Ridge and Petermann Fjord. The sites span water depths of 52–1157 m and bottom water temperatures (BWT) of −1.8 to +0.9 °C. Benthic foraminifera were alive at time of collection, determined from Rose Bengal (RB) staining. Three infaunal and three epifaunal species were abundant enough for Mg/Ca analysis. As predicted by theory and empirical evidence, cold water Arctic Ocean benthic species produce low Mg/Ca ratios, the exception being the porcelaneous species Quinqueloculina arctica. Our new data provide important constraints at the cold end (<1 °C) when added to existing global datasets. The refined calibrations based on the new and published global data appear best supported for the infaunal species Nonionella labradorica (Mg/Ca = 1.325 ± 0.01 × e^(0.065 ± 0.01 × BWT), r2 = 0.9), Cassidulina neoteretis (Mg/Ca = 1.009 ± 0.02 × e^(0.042 ± 0.01 × BWT), r2 = 0.6) and Elphidium clavatum (Mg/Ca = 0.816 ± 0.06 + 0.125 ± 0.05 × BWT, r2 = 0.4). The latter is based on the new Arctic data only. This suggests that Arctic Ocean infaunal taxa are suitable for capturing at least relative and probably semi-quantitative past changes in BWT. Arctic Oridorsalis tener Mg/Ca data are combined with existing O. umbonatus Mg/Ca data from well saturated core-tops from other regions to produce a temperature calibration with minimal influence of bottom water carbonate saturation state (Mg/Ca = 1.317 ± 0.03 × e^(0.102 ± 0.01 BWT), r2 = 0.7). The same approach for Cibicidoides wuellerstorfi yields Mg/Ca = 1.043 ± 0.03 × e^(0.118 ± 0.1 BWT), r2 = 0.4. Mg/Ca ratios of the porcelaneous epifaunal species Q. arctica show a clear positive relationship between Mg/Ca and Δ[CO32−] indicating that this species is not suitable for Mg/Ca-palaeothermometry at low temperatures, but may be useful in reconstructing carbonate system parameters through time.
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| 48. |
- Barrientos, Natalia, 1985-
(författare)
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Arctic Ocean benthic foraminifera preservation and Mg/Ca ratios : Implications for bottom water palaeothermometry
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Reconstructions of Arctic Ocean palaeotemperatures are needed to disentangle natural variability from anthropogenic changes and understand the role of ocean heat transport in forcing or providing feedbacks on Arctic climate change. Despite known complications with calcareous microfossil preservation in Arctic Ocean sediments, calcareous benthic foraminifera can be common in interglacial sequences. However, thus far they have been underutilized in palaeoceanographic studies. This thesis explores the application of the Mg/Ca palaeothermometry proxy for reconstructing bottom water temperatures (BWT) in the Arctic Ocean during the late Quaternary. This method, which is supported by previous empirical studies demonstrating a strong temperature control on trace Mg inclusion into foraminiferal shell calcite, has been applied in many ocean regions and time intervals. Until now its application in the Arctic Ocean has been sparingly explored.The results of this doctoral thesis are based on benthic foraminifera retrieved from marine sediment cores covering a wide geographical Arctic Ocean area including both the shallow and vast continental shelves and slopes to the intermediate-to-deep waters of the Lomonosov Ridge and Morris Jesup Rise. These provide the first benthic foraminifera Mg/Ca ratios from the central Arctic Ocean region. In the first study, mechanisms that could affect Mg incorporation in Arctic benthic foraminifera are investigated using oceanographic field data and six 'live' modern Arctic species (Elphidium clavatum, Nonionella labradorica, Cassidulina neoteretis, Oridorsalis tener, Cibicidoides wuellerstorfi and Quinqueloculina arctica). The result is new species-specific Mg/Ca–BWT field calibrations that provide important constraints at the cold end of the BWT spectrum (-2 to 1°C) (Paper I). Using the new Mg/Ca–BWT equation for E. clavatum, a palaeotemperature record was generated for the late Holocene (past ca. 4100 yr) from the western Chukchi Sea. The data showed BWT fluctuations from -2 to 1°C that are interpreted as showing pulses of warmer Pacific water inflow at 500–1000 yr periods, thus revealing multi-centennial variability in heat transport into the Arctic Ocean driven by low latitude forcings (Paper II). Complications with foraminiferal calcite preservation that limit Mg/Ca palaeothermometry in the Arctic were discovered and these are tackled in two additional papers. Anomalously high Mg content in benthic foraminifera from the central Arctic Ocean is linked to diagenetic contamination as a result of the unique oceanographic, sedimentary and geochemical environment (Paper III). Lastly, the dramatic post-recovery dissolution of foraminifera from a Chukchi Shelf sediment core during core storage is investigated and attributed to acidification driven by sulphide oxidation in this organic rich and calcite poor shelf setting (Paper IV).The findings of this thesis demonstrate that benthic foraminiferal Mg/Ca-palaeothermometry can be applied in the Arctic Ocean and capture small BWT change (on the order of -2 to 2°C) even at low temperatures. In practice, preservational complexities can be limiting and require special sample handling or analysis due to the high potential for diagenetic contamination in the central Arctic Ocean and rapid post coring calcite dissolution in the seasonally productive shelf seas. This Ph.D. project is a component of the multidisciplinary SWERUS-C3 (Swedish-Russian-US Arctic Ocean Climate-Cryosphere- Carbon Interactions) project that included an expedition with Swedish icebreaker Oden to the East Siberian Arctic Ocean.
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