| 1. |
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| 2. |
- Drake, Henrik, 1979-, et al.
(författare)
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Ancient microbial activity in deep hydraulically conductive fracture zones within the Forsmark target area for deep geological nuclear waste disposal, Sweden
- 2018
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Ingår i: Geosciences. - : MDPI AG. - 2076-3263. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Recent studies reveal that organisms from all three domains of life—Archaea, Bacteria, and even Eukarya—can thrive under energy-poor, dark, and anoxic conditions at large depths in the fractured crystalline continental crust. There is a need for an increased understanding of the processes and lifeforms in this vast realm, for example, regarding the spatiotemporal extent and variability of the different processes in the crust. Here, we present a study that set out to detect signs of ancient microbial life in the Forsmark area—the target area for deep geological nuclear waste disposal in Sweden. Stable isotope compositions were determined with high spatial resolution analyses within mineral coatings, and mineralized remains of putative microorganisms were studied in several deep water-conducting fracture zones (down to 663 m depth), from which hydrochemical and gas data exist. Large isotopic variabilities of 13Ccalcite (?36.2 to +20.2‰V-PDB) and 34Spyrite (?11.7 to +37.8‰V-CDT) disclose discrete periods of methanogenesis, and potentially, anaerobic oxidation of methane and related microbial sulfate reduction at several depth intervals. Dominant calcite–water disequilibrium of 18O and 87Sr/86Sr precludes abundant recent precipitation. Instead, the mineral coatings largely reflect an ancient archive of episodic microbial processes in the fracture system, which, according to our microscale Rb–Sr dating of co-genetic adularia and calcite, date back to the mid-Paleozoic. Potential Quaternary precipitation exists mainly at ~400 m depth in one of the boreholes, where mineral–water compositions corresponded.
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| 3. |
- Omstedt, Anders, 1949
(författare)
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The Development of Climate Science of the Baltic Sea Region
- 2017
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Ingår i: Oxford Research Encyclopedia of Climate Science. - : Oxford University Press.
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Dramatic climate changes have occurred in the Baltic Sea region caused by changes in orbital movement in the earth–sun system and the melting of the Fennoscandian Ice Sheet. Added to these longer-term changes, changes have occurred at all timescales, caused mainly by variations in large-scale atmospheric pressure systems due to competition between the meandering midlatitude low-pressure systems and highpressure systems. Here we follow the development of climate science of the Baltic Sea from when observations began in the 18th century to the early 21st century. The question of why the water level is sinking around the Baltic Sea coasts could not be answered until the ideas of postglacial uplift and the thermal history of the earth were better understood in the 19th century and periodic behavior in climate related time series attracted scientific interest. Herring and sardine fishing successes and failures have led to investigations of fishery and climate change and to the realization that fisheries themselves have strongly negative effects on the marine environment, calling for international assessment efforts. Scientists later introduced the concept of regime shifts when interpreting their data, attributing these to various causes. The increasing amount of anoxic deep water in the Baltic Sea and eutrophication have prompted debate about what is natural and what is anthropogenic, and the scientific outcome of these debates now forms the basis of international management efforts to reduce nutrient leakage from land. The observed increase in atmospheric CO and its effects on global warming have focused the climate debate on trends and generated a series of international and regional assessments and research programs that have greatly improved our understanding of climate and environmental changes, bolstering the efforts of earth system science, in which both climate and environmental factors are analyzed together.
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| 4. |
- Bobrowski, Nicole, et al.
(författare)
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Multi-component gas emission measurements of the active lava lake of Nyiragongo, DR Congo
- 2017
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Ingår i: Journal of African Earth Sciences. - : Elsevier BV. - 1879-1956 .- 1464-343X. ; 134, s. 856-865
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Tidskriftsartikel (refereegranskat)abstract
- Between 2007 and 2011 four measurement campaigns (June 2007, July 2010, June 2011, and December 2011) were carried out at the crater rim of Nyiragongo volcano, DR Congo. Nyiragongo is one of the most active volcanoes in Africa. The ground-based remote sensing technique Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS), which uses scattered sunlight, the in-situ Multi-Component Gas Analyzer System (Multi-GAS) and alkaline impregnated filter were simultaneously applied during all field trips. The bromine monoxide to sulfur dioxide (BrO/SO2) and carbon dioxide to sulfur dioxide (CO2/SO2) molar ratios were determined, among other ratios. During the different field trips variations of the level of the lava lake up to several tens of meters were observed during intervals of the order of minutes up to days and also between the years. The measured gas ratios presented covariations with the lava lake level changes. BrO/SO2 ratios and CO2/SO2 ratios showed similar behavior. Annual CO2/SO2 and BrO/SO2 average values are generally positively correlated. In June 2011 increased BrO/SO2 as well as increased CO2/SO2 ratios have been observed before a sudden decrease of the lava lake. Overall the Cl/S ratio, determined by filter-pack sampling, shows an increasing trend with time, which is accompanied by a decreasing sulfur dioxide flux, the later measured nearly continuously by automated MAX-DOAS instruments since 2004. Mean gas emission fluxes of CO2, Cl and ‘minimum-BrO’ fluxes are calculated using their ratio to SO2. The first two show an increase with time, in contrast to the SO2 fluxes. A simple conceptual model is proposed which can explain in particular the June 2011 data, but as well our entire data set. The proposed model takes up the idea of convective magma cells inside the conduit and the possible temporary interruption of part of the cycling. We propose than two alternatives to explain the observed gas emission variation: 1. It is assumed that the diffuse and fumarolic degassing could have significant influence on measured gas composition. The measured gas composition might rather represent a gas mixture of plume, diffuse and fumarolic degassing than only representing the volcanic plume. 2. It is proposed that the interruption of the convection has taken place in the upper part of the conduit and deep degassing of CO2 and bromine initially continues while mixing already with gas emissions from an ageing source, which is characterized by an already diminishing sulfur content. These complex process but as well as the gas mixing of different sources, could explain general features of our dataset, but can unfortunately neither be confirmed nor disproven by the data available today.
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| 5. |
- Ledesma, Jose, et al.
(författare)
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Aquatic DOC export from subarctic Atlantic blanket bog in Norway is controlled by seasalt deposition, temperature and precipitation
- 2016
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Ingår i: Biogeochemistry. - : Springer Science and Business Media LLC. - 0168-2563 .- 1573-515X. ; 127, s. 305-321
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Tidskriftsartikel (refereegranskat)abstract
- Comprehensive and credible peatland carbon budgets, needed for global carbon accounting, must include lateral aquatic organic carbon export. Here, we quantify aquatic dissolved organic carbon (DOC) export for an Atlantic bog in subarctic Norway, the Andøya peatland, and test for sensitivity to climatic drivers. Hydrology, DOC concentrations and DOC export were simulated for 2000–2013 using the process-based catchment model Integrated Catchments model for Carbon(INCA-C), calibrated to site-specific water chemistry and hydrology (2011–2014) using readily-available data on temperature, precipitation and seasalt deposition. Measured streamwater DOC declined under seasalt episodes and was strongly positively related to temperature. Model calibrations successfully reproduced the water balance, variation in runoff (R2=0.67; Nash–Sutcliffe model efficiency NS=0.67) and DOC concentrations (R2=0.85; NS=0.84). The most sensitive model parameters related to temperature-sensitivity of DOC production and DOC (de)sorption sensitivity to seasalts. Model uncertainty related to parameter space was similar to interannual variation in DOC export. Mean annual modelled DOC export was 7.2±0.7g C m−2 year−1, roughly 35% of the net land–atmospheric CO2 exchange at Andøya from 2009 to 2012 (estimated elsewhere). Current and antecedent mean temperature and precipitation were strong drivers of seasonal modelled DOC export, implying that warmer and wetter summers will lead to more DOC export. Evaluation of similar climate impacts on net peatland carbon accumulation requires additional exploration of the climate-sensitivity of land–atmosphere fluxes of CO2 and methane. Process-based models are valuable tools to account for lateral DOC exports in carbon balances of northern peatlands, especially where long-term monitoring data are lacking.
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| 6. |
- Myers-Smith, Isla H., et al.
(författare)
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Complexity revealed in the greening of the Arctic
- 2020
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Ingår i: Nature Climate Change. - : Springer Science and Business Media LLC. - 1758-678X .- 1758-6798. ; 10:2, s. 106-117
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Tidskriftsartikel (refereegranskat)abstract
- As the Arctic warms, vegetation is responding, and satellite measures indicate widespread greening at high latitudes. This ‘greening of the Arctic’ is among the world’s most important large-scale ecological responses to global climate change. However, a consensus is emerging that the underlying causes and future dynamics of so-called Arctic greening and browning trends are more complex, variable and inherently scale-dependent than previously thought. Here we summarize the complexities of observing and interpreting high-latitude greening to identify priorities for future research. Incorporating satellite and proximal remote sensing with in-situ data, while accounting for uncertainties and scale issues, will advance the study of past, present and future Arctic vegetation change.
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| 7. |
- Hassellöv, Ida-Maja, 1974, et al.
(författare)
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Miljörisker sjunkna vrak II. Undersökningsmetoder och miljöaspekter
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- During 2015 the Swedish Maritime Administration continued the second phase of thegovernmental task Environmental risks from sunken wrecks which first report was finalized2014-10-31 (Dnr: 1399-14-01942-6).The main conclusions from the 2014 report remain; for future handling of potentially pollutingshipwrecks it is recommended that the Swedish Agency for Water and Marine Management isgiven a coordinating responsibility in close cooperation with other competent nationalauthorities, such as Swedish Maritime Administration, Swedish Coastguard, Swedish NationalMaritime Museums, the Geological Survey of Sweden, SMHI, Swedish EPA, and SwedishCivil Contingencies Agency. Through coordination of wreck related operations and activitieswithin the concerned competent authorities’ ordinary areas of responsibility, resourceefficiency is improved. The estimated extra cost for implementation of a national strategy forhandling of the wrecks are estimated to be 10-15 MSEK which should be allocated to thecompetent authorities by the Swedish Agency for Water and Marine Management.The conclusions from 2014 was reinforced during 2015, e.g. through the validation of the riskassessment model VRAKA, which is now available in a first operative version. Additionalecotoxicological experiments on the development of tolerance against PAHs in meiofauna andmicroorganism communities were conducted in a field study in Brofjorden. The mainconclusions from this work is that comprehensive analyzes of PAHs should include alkylatedPAHs, and that exposure to PAHs over time can lead to tolerance development in ammoniumoxidizing bacteria, at the expense of their ability to perform the essential ecosystem servicenitrification.Continued measurements of the bottom currents were made at the wrecks Villon and Skytteren,and at the dumping area west of Måseskär. Measurement series yielded important informationon how measuring equipment at the wreck can be deployed in an optimized way in futuremonitoring program; to calculate the possible spreading of pollution from a wreck, currentmeasurements should be performed upstream from the wreck site, while sensors for thedetection of, for example, oil should be put into the turbulence downstream of the wreck.The current measurement instruments (RDCP) deployed at the Måseskär dump site was trawledup after only three weeks of measurements, but still gave valuable information on the extensivebottom trawling that resuspend (stir up) sediments. Earlier geochemical surveys have shownsignificantly elevated arsenic concentrations in the area and sediment resuspension greatlyincreased the risk for spread of any contaminants in the area. Trawling is not prohibited in thearea, and the current lack of knowledge regarding potential effects on human health whenconsuming seafood from dump areas calls for reflection upon the suitability of trawling in thearea.In addition to the current measurements Swedish Maritime Administration and the SwedishNavy conducted hydrographic survey with multibeam and side scan sonar and ROVinvestigation of the wrecks in the dumping area at Måseskär. 28 wrecks were found, and ROVinvestigation showed cargo holds with dumped torpedoes or mines and other containers in some SjöfartsverketDnr: 1399-14-01942-156of the wrecks. There is some discrepancy between the previously measured elevated arsenicconcentrations in the Måseskär area and recently presented data from historical archives thatdoes not support the theory that chemical weapons were dumped in the area. However, there isa very good correlation between the dominant current direction in the area, and the highestmeasured arsenic concentrations in the area downstream of the wrecks, suggesting some formof arsenic source in the area.
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| 8. |
- Kylander, Malin, 1977-, et al.
(författare)
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A novel geochemical approach to paleorecords of dust deposition and effective humidity: 8500 years of peat accumulation at Store Mosse (the "Great Bog") , Sweden )
- 2013
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 69, s. 69-82
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Tidskriftsartikel (refereegranskat)abstract
- Both bog surface wetness and atmospheric dust deposition are intricately linked to changes in the hydrological cycle and pairing these types of records at the same site provides complementary information. Here a peat core from Store Mosse in southern Sweden covering the last 8500 years was used to make a high-resolution paleoclimate reconstruction based on a combination of bog development, colourimetric humification and inorganic geochemistry data. The coupling of Principal Component Analysis with changepoint modelling allowed for precise linking of changes in bog surface wetness and dust deposition records.A long-term trend towards warm (and possibly wet) conditions starts ca 8150 cal yr BP and culminates with the most pronounced conditions from 6900 to 6600 cal yr BP. The most significant arid period at Store Mosse occurred between 6500 and 5600 cal yr BP during which dust deposition was significantly higher. Wetter conditions dominate from 5500 to 4980 cal yr BP as the transition from the Hypsithermal and into the Neoglacial is made. After a shift to drier conditions, humification enters a more stable period that lasts from 4525 until 3200 cal yr BP. It is during this time that the first possible anthropogenic dust signals occur at ca 4200 cal yr BP. From 3200 cal yr BP to present humification generally shows a long-term decline moving towards wetter conditions. The main exceptions are during the transition from the Neoglacial to Roman Warm Period which is registered as a significantly wetter period and two dry periods recorded 2365 to 2155 cal yr BP and 1275–1105 cal yr BP. In general, the observed changes agree well with regional records of effective humidity and temperature. The high temporal resolution of the Store Mosse record reveals that palaeoclimatic change over the last 8500 years in southern Sweden has had a complex and variable structure.
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| 9. |
- Kylander, Malin E., et al.
(författare)
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Mineral dust as a driver of carbon accumulation in northern latitudes
- 2018
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Peatlands in northern latitudes sequester one third of the world's soil organic carbon. Mineral dusts can affect the primary productivity of terrestrial systems through nutrient transport but this process has not yet been documented in these peat-rich regions. Here we analysed organic and inorganic fractions of an 8900-year-old sequence from Store Mosse (the "Great Bog") in southern Sweden. Between 5420 and 4550 cal yr BP, we observe a seven-fold increase in net peat-accumulation rates corresponding to a maximum carbon-burial rate of 150 g C m(-2) yr(-1) -more than six times the global average. This high peat accumulation event occurs in parallel with a distinct change in the character of the dust deposited on the bog, which moves from being dominated by clay minerals to less weathered, phosphate and feldspar minerals. We hypothesize that this shift boosted nutrient input to the bog and stimulated ecosystem productivity. This study shows that diffuse sources and dust dynamics in northern temperate latitudes, often overlooked by the dust community in favour of arid and semi-arid regions, can be important drivers of peatland carbon accumulation and by extension, global climate, warranting further consideration in predictions of future climate variability.
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| 10. |
- Weis, Franz A., et al.
(författare)
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Magmatic water contents determined through clinopyroxene : Examples from the Western Canary Islands, Spain
- 2015
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Ingår i: Geochemistry Geophysics Geosystems. - 1525-2027. ; 16:7, s. 2127-2146
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Tidskriftsartikel (refereegranskat)abstract
- Water is a key parameter in magma genesis, magma evolution, and resulting eruption styles, because it controls the density, the viscosity, as well as the melting and crystallization behavior of a melt. The parental water content of a magma is usually measured through melt inclusions in minerals such as olivine, a method which may be hampered, however, by the lack of melt inclusions suitable for analysis, or postentrapment changes in their water content. An alternative way to reconstruct the water content of a magma is to use nominally anhydrous minerals (NAMs), such as pyroxene, which take up low concentrations of hydrogen as a function of the magma's water content. During magma degassing and eruption, however, NAMs may dehydrate. We therefore tested a method to reconstruct the water contents of dehydrated clinopyroxene phenocrysts from the Western Canary islands (n=28) through rehydration experiments followed by infrared and Mossbauer spectroscopy. Employing currently available crystal/melt partitioning data, the results of the experiments were used to calculate parental water contents of 0.710.07 to 1.490.15 wt % H2O for Western Canary magmas during clinopyroxene crystallization at upper mantle conditions. This H2O range is in agreement with calculated water contents using plagioclase-liquid-hygrometry, and with previously published data for mafic lavas from the Canary Islands and comparable ocean island systems elsewhere. Utilizing NAMs in combination with hydrogen treatment can therefore serve as a proxy for pre-eruptive H2O contents, which we anticipate becoming a useful method applicable to mafic rocks where pyroxene is the main phenocryst phase.
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