Holocene Varved Lake Sediments as Records of Palaeoenvironmental Change and Geomagnetic Palaeosecular Variation in Eastern Finland

This dissertation discusses Holocene palaeoenvironmental and palaeomagnetic secular variation (PSV) records reconstructed from sediments preserved in Lake Lehmilampi (63º37´N, 29º06´E) and Lake Kortejärvi (63º37´N, 28º56´E) in eastern Finland. Several piston and freeze cores were obtained from both lakes for varve and magnetic analyses. Sediment samples were impregnated in low-viscosity epoxy and physical parameters of varves, including varve thickness and relative grey-scale values, were recorded using x-ray densitometry combined with semiautomatic digital image analysis. On average, varve records of Lehmilampi and Kortejärvi cover 5122 and 3902 years, respectively. Past solar activity, as estimated by residual 14C data, compares favourably with varve thicknesses from Lehmilampi during the last 2000 years. This indicates the potential of clastic-organic varves to record sensitively climatic variations. Bulk magnetic parameters, including magnetic susceptibility together with natural, anhysteretic and isothermal remanent magnetizations, were measured to describe mineral magnetic properties and geomagnetic palaeosecular variation recorded in the sediments. Main stages in the development of the investigated lakes are reflected in the variations in the mineral magnetic records, sediment lithology and composition. Similar variations in magnetic parameters and sediment organic matter suggest contribution of bacterial magnetite in the magnetic assemblages of Lehmilampi. Inclination and relative declination records yielded largely consistent results, attesting to the great potential of these sediments to preserve directional palaeosecular variation in high resolution. The PSV data from Lehmilampi and Kortejärvi were stacked into North Karelian PSV stack, which may be used for dating homogenous lake sediments in the same regional context. Reconstructed millennial variations in relative palaeointensity results are approximately in agreement with those seen in the absolute palaeointensity data from Europe. Centennial variations in the relative palaeointensity, however, are influenced by environmental changes. Caution is recommended when using varved lake sediments in reconstructing relative palaeointensity.Siirretty Doriast

Assessing the utilization of the decision to implement a palliative goal for the treatment of cancer patients during the last year of life at Helsinki University Hospital : a historic cohort study

Background: To avoid aggressive treatments at the end-of-life and to provide palliative care (PC), physicians need to terminate futile anti-cancer treatments and define the palliative goal of the treatment in time. This single center study assesses the practices used to make the decision that leads to treatment with a palliative goal, i.e., the PC decision and its effect on anti-cancer treatments at the end of life. Material and methods: Patients with a cancer diagnosis treated in tertiary hospital during 1st January 2013 - 31st December 2014 and deceased by the end of 2014 were identified in the hospital database (N = 2737). Of these patients, 992 were randomly selected for this study. The PC decision was screened from patient records, i.e., termination of cancer-specific treatments and a focus on symptom-centered PC. Results: The PC decision was defined in 82% of the patients during the last year of life (49% >30 days and 33%Peer reviewe

The impact of the duration of the palliative care period on cancer patients with regard to the use of hospital services and the place of death : a retrospective cohort study

Background In order to avoid unnecessary use of hospital services at the end-of-life, palliative care should be initiated early enough in order to have sufficient time to initiate and carry out good quality advance care planning (ACP). This single center study assesses the impact of the PC decision and its timing on the use of hospital services at EOL and the place of death. Methods A randomly chosen cohort of 992 cancer patients treated in a tertiary hospital between Jan 2013 -Dec 2014, who were deceased by the end of 2014, were selected from the total number of 2737 identified from the hospital database. The PC decision (the decision to terminate life-prolonging anticancer treatments and focus on symptom centered palliative care) and use of PC unit services were studied in relation to emergency department (ED) visits, hospital inpatient days and place of death. Results A PC decision was defined for 82% of the patients and 37% visited a PC unit. The earlier the PC decision was made, the more often patients had an appointment at the PC unit (> 180 days prior to death 72% and <14 days 10%). The number of ED visits and inpatient days were highest for patients with no PC decision and lowest for patients with both a PC decision and an PC unit appointment (60 days before death ED visits 1.3 vs 0.8 and inpatient days 9.9 vs 2.9 respectively, p <0.01). Patients with no PC decision died more often in secondary/tertiary hospitals (28% vs. 19% with a PC decision, and 6% with a decision and an appointment to a PC unit). Conclusions The PC decision to initiate a palliative goal for the treatment had a distinct impact on the use of hospital services at the EOL. Contact with a PC unit further increased the likelihood of EOL care at primary care.Peer reviewe

The impact of the duration of the palliative care period on cancer patients with regard to the use of hospital services and the place of death: a retrospective cohort study

Background: In order to avoid unnecessary use of hospital services at the end-of-life, palliative care should be initiated early enough in order to have sufficient time to initiate and carry out good quality advance care planning (ACP). This single center study assesses the impact of the PC decision and its timing on the use of hospital services at EOL and the place of death. Methods: A randomly chosen cohort of 992 cancer patients treated in a tertiary hospital between Jan 2013 -Dec 2014, who were deceased by the end of 2014, were selected from the total number of 2737 identified from the hospital database. The PC decision (the decision to terminate life-prolonging anticancer treatments and focus on symptom centered palliative care) and use of PC unit services were studied in relation to emergency department (ED) visits, hospital inpatient days and place of death. Results: A PC decision was defined for 82% of the patients and 37% visited a PC unit. The earlier the PC decision was made, the more often patients had an appointment at the PC unit (> 180 days prior to death 72% and Conclusions: The PC decision to initiate a palliative goal for the treatment had a distinct impact on the use of hospital services at the EOL. Contact with a PC unit further increased the likelihood of EOL care at primary care.</div

Sediment profile dating and reconstructing nuclear events from annually laminated lake sediments in northern Finland

Ydinpommikokeiden ja Tšernobyl laskeuman havainnointi Kevojärven lustosedimenteistä Säteilyturvakeskus tutki Turun yliopiston kanssa Utsjoen Kevojärven lustosedimenttejä. Tarkoitus Utsjoella sijaitsevan Kevojärven pohjaan sedimentti kertyy kerroksellisina lustosedimentteinä, joissa vuotuinen kevättulva näkyy hiekkakerroksena ja kesän aikana pohjaan kertyy humuksesta orgaaninen kerros. Tämä rakennelma muistuttaa puun vuosirenkaita, mistä nimitys lustosedimentti johtuu. Säteilyturvakeskus mittasi lustoista vuosittain kertyneen orgaanisen kerroksen radioaktiivisuuden ajalta 1913-2009. Mittauksissa mitattiin gammasäteilyä lähettävät radioisotoopit, joissa päämielenkiinto kohdistui keinotekoisiin cesium-137 ja amerikium-241 isotooppeihin sekä luonnossa esiintyvään lyijy-210:en. Tulokset Mittauksista saatiin rakennettua aikasarja, joka kuvaa Utsjoella tapahtunutta historiallista radioaktiivisten aineiden laskeumaa. Cesium-137:n aikasarjassa havaittiin Tšernobylin ydinvoimalaitosonnettomuudesta johtuva aktiivisuuspitoisuuden nousu, 1970-luvun alussa Kiinan ja Ranskan ilmakehässä tekemät ydinasekokeet sekä 1960-luvun alun intensiivinen ilmakehässä tehtyjen ydinasekokeiden jakso. Varmuudella ei pystytä sanomaan, milloin ensimmäiset radioaktiiviset cesium-137 -hiukkaset saapuivat Kevojärvelle, mutta ensimmäinen selkeä nousu sedimenttien pitoisuuksissa havaittiin 1956. Amerikium-241 -pitoisuuksissa havaitaan samat asiat kuin cesium-137:n pitoisuuksissa lukuun ottamatta Tšernobylin onnettomuutta, josta tuli hyvin vähän amerikium-241:n lähtöisotooppia plutonium-241:tä. Lyijy-210 on luonnon radioaktiivinen aine ja pääasiallisesti se kaukokulkeutuu Kevojärvelle ilmavirtauksien mukana. Viimeisen 80 vuoden aikana lyijy-210 laskeuma järveen on ollut tasainen eikä aikasarjassa havaita ilmastonmuutoksen vaikutusta

Snowmelt layer thickness in varved Lake Kortejärvi sediments

Sediment microfacies, geochemical µ-XRF and X-ray density analyses were conducted on varved sediments from Lake Kortejärvi (eastern Finland) covering the last 2700 years. Varves comprise couplets of detrital and organic sub-layers throughout the complete time-span. Based on their microfacies and stratigraphic position within a varve as well as comparisons with local discharge and meteorological data, thicker detrital layers are interpreted to reflect intensified snowmelt floods following more humid winters. Detailed comparisons with monthly to annually resolved North Atlantic Oscillation (NAO) indices back to AD 1049 (901 a BP) suggest that multi-decadal increases in snowmelt layer thickness tend to be connected with a more positive phase of the NAO and, consequently, warmer winters. In contrast, distinct centennial intervals of thicker snowmelt layers from -40 to 170, 280 to 460 and 1900 to 2300 a BP as well as around 2600 a BP do not consistently correspond to a particular NAO phase, but coincide with extended sea ice margins and a colder North Atlantic climate, causing intensified and southward shifted westerly cyclones. Our results point to a differential modification of North Atlantic winter hydroclimate working on varying time-scales

Radiocarbon Wiggle-Match Dating of Bulk Sediments-How Accurate Can it Be?

We used the radiocarbon wiggle-match dating technique to date the varved sediments of Lake Gyltigesjon in southern Sweden with the main aim to construct an accurate chronology covering the period between about 3000 and 2000 cal BP. Wiggle-match dating was applied to bulk sediments to evaluate the possibility of constructing accurate chronologies in the absence of terrestrial plant macrofossils and when the amount of old carbon in the sediments is unknown. Facilitated by a floating varve chronology and relatively stable C-14 reservoir ages, the results show the possibility to assess the contribution of old carbon solely based on the C-14 wiggle-matching of bulk sediments. We confirm the wiggle-matched chronology and the C-14 reservoir age of approximately 260 yr by cross-checking the results with C-14 dating of macrofossils. The obtained calibrated ages based on bulk sediments have an uncertainty range of about 60-65 yr (95.4% confidence interval). This study confirms that C-14 wiggle-match dating of bulk sediments is a viable tool when constructing high-resolution chronologies. The method is especially useful in Sun-climate studies since the timing between solar activity variations (expressed as C-14 variations) and climate changes can be accurately determined

An estimate of post-depositional remanent magnetization lock-in depth in organic rich varved lake sediments

We studied the paleomagnetic properties of relatively organic rich, annually laminated (varved) sediments of Holocene age in Gyltigesjon, which is a lake in southern Sweden. An age-depth model was based on a regional lead pollution isochron and Bayesian modelling of radiocarbon ages of bulk sediments and terrestrial macrofossils, which included a radiocarbon wiggle-matched series of 873 varves that accumulated between 3000 and 2000 Cal a BP (Mellstrom et al., 2013). Mineral magnetic data and first order reversal curves suggest that the natural remanent magnetization is carried by stable single-domain grains of magnetite, probably of magnetosomal origin. Discrete samples taken from overlapping piston cores were used to produce smoothed paleomagnetic secular variation (inclination and declination) and relative paleointensity data sets. Alternative temporal trends in the paleomagnetic data were obtained by correcting for paleomagnetic lock-in depths between 0 and 70 cm and taking into account changes in sediment accumulation rate. These temporal trends were regressed against reference curves for the same region (FENNOSTACK and FENNORPIS; Snowball et al., 2007). The best statistical matches to the reference curves are obtained when we apply lock-in depths of 21-34 cm to the Gyltigesjon paleomagnetic data, although these are most likely minimum estimates. Our study suggests that a significant paleomagnetic lock-in depth can affect the acquisition of post-depositional remanent magnetization even where bioturbation is absent and no mixed sediment surface layer exists. (C) 2013 The Authors. Published by Elsevier B.V. All rights reserved