| 1. |
- Comstedt, Daniel, et al.
(författare)
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Autotrophic and heterotrophic soil respiration in a Norway spruce forest : estimating the root decomposition and soil moisture effects in a trenching experiment
- 2011
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Ingår i: Biogeochemistry. - : Springer. - 0168-2563 .- 1573-515X. ; 104:1-3, s. 121-132
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Tidskriftsartikel (refereegranskat)abstract
- The two components of soil respiration, autotrophic respiration (from roots, mycorrhizal hyphae and associated microbes) and heterotrophic respiration (from decomposers), was separated in a root trenching experiment in a Norway spruce forest. In June 2003, cylinders (29.7 cm diameter) were inserted to 50 cm soil depth and respiration was measured both outside (control) and inside the trenched areas. The potential problems associated with the trenching treatment, increased decomposition of roots and ectomycorrhizal mycelia and changed soil moisture conditions, were handled by empirical modelling. The model was calibrated with respiration, moisture and temperature data of 2004 from the trenched plots as a training set. We estimate that over the first 5 months after the trenching, 45% of respiration from the trenched plots was an artefact of the treatment. Of this, 29% was a water difference effect and 16% resulted from root and mycelia decomposition. Autotrophic and heterotrophic respiration contributed to about 50% each of total soil respiration in the control plots averaged over the two growing seasons. We show that the potential problems with the trenching, decomposing roots and mycelia and soil moisture effects, can be handled by a modelling approach, which is an alternative to the sequential root harvesting technique.
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| 2. |
- Ekblad, Alf, 1957-, et al.
(författare)
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Deforestation releases old carbon
- 2019
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Ingår i: Nature Geoscience. - : Nature Publishing Group. - 1752-0894 .- 1752-0908. ; 12:7, s. 499-500
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Tidskriftsartikel (refereegranskat)abstract
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| 3. |
- Mörner, Nils-Axel, 1938-
(författare)
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In absurdum : long-term predictions and nuclear waste handling
- 2001
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Ingår i: Engineering Geology. - 0013-7952 .- 1872-6917. ; 61:2-3, s. 75-82
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Tidskriftsartikel (refereegranskat)abstract
- Careful use of scientific knowledge allows predictions into the future. When the time units for our predictions increases to hundreds of thousands of years, we have extended our abilities 'in absurdum'. This is true for long-term safety statements regarding the handling of our high-level nuclear waste. The Fennoscandian Shield has been claimed to offer exceptionally stable bedrock conditions over immense time periods. We only need to go back to the last deglacial phase some 10,000 years ago to have a totally different situation from that of today. At that time Sweden was characterized by exceptionally high seismic activity; both in amplitude and frequency. These conditions (like a number of related phenomena) will be repeated at future lee Ages. In such an environment, there can be no safe repository in the bedrock. In the absence of true long-term safety, we can only recommend the utilization of the Dry Rock Deposit (DRD) method where the waste is stored in the bedrock under dry conditions, under constant control and monitoring, accessible for maintenance and possible future methods of rendering the waste harmless and even removal. (C) 2001 Elsevier Science B.V. All rights reserved.
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| 4. |
- Weber, Michael E., et al.
(författare)
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200,000 years of monsoonal history recorded on the lower Bengal Fan - strong response to insolation forcing
- 2018
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Ingår i: Global and Planetary Change. - : Elsevier. - 0921-8181 .- 1872-6364. ; 166, s. 107-119
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Tidskriftsartikel (refereegranskat)abstract
- We conducted a multidisciplinary study to provide the stratigraphic and palaeoclimatic context of monsoonal rainfall dynamics and their responses to orbital forcing for the Bay of Bengal. Using sediment lightness we established an age model at orbital resolution for International Ocean Discovery Programme (IODP) Core U1452C-1H that covers the last 200 ka in the lower Bengal Fan. The low-resolution delta O-18 of G. sacculifer is consistent with global delta O-18 records, at least for major glacial-to-interglacial transitions. The variability of total organic carbon, total nitrogen, and the delta C-13 composition of organic matter indicate the marine origin of organic matter. Marine primary productivity likely increased during insolation minima, indicative for an enhanced NE monsoon during glacials and stadials. Pristine insolation forcing is also documented for wet-bulk density, red green color variability, and grain-size variations, indicating that darker and coarser-grained material deposited at higher sedimentation rates during insolation minima. Stronger NE monsoon likely amplified ocean-atmosphere interactions over the Indian Ocean, leading to stronger upwelling through shoaling the thermocline, and higher delivery of sediment to the Bay of Bengal due to higher soil erosion on land. In addition, lower glacial and stadial sea levels as well as stronger westward surface circulation favored delivery of coarser-grained fluvial material to the lower Bengal Fan. At the same time the stronger NE monsoon might have increased the aeolian supply. Total inorganic carbon, the Ca/Ti ratio, and biogenic silica vary dominantly on obliquity frequencies, suggesting mobilization and transport of lithogenic material primarily during lowered sea levels and/or higher influence of the Northern Hemisphere westerlies on the dust transport from the Tibetan Plateau. The close resemblance of sediment lightness and the climate record of Antarctic ice cores over multiple glacial cycles indicate close relationship between high southern latitude and tropical Asian climate through shifts in position of the Intertropical Convergence Zone. The Bengal Fan monsoonal record shows very clear and strict responses to insolation forcing in the lower part from -200 ka to the Younger Toba Tuff during Marine Isotope Stage (MIS) 7 - 5, and less distinct response patterns after deposition of the ash during MIS 4- 2, consistent with low-amplitude changes in insolation.
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| 5. |
- Misra, Satabdi, et al.
(författare)
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Multi-proxy approach on the hydrocarbon generation perspective of Barjora Basin, India
- 2020
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Ingår i: Marine and Petroleum Geology. - : Elsevier. - 0264-8172 .- 1873-4073. ; 112
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Tidskriftsartikel (refereegranskat)abstract
- Barjora Basin in India is a small basin characterized by a high organic richness of early mature nature. The present study aims to find the source of organic matter (OM) and hydrocarbon generation potential of Barjora Basin. Systematically collected coal and shale samples from R-II seam of the basin were used for proximate and ultimate analyses, Rock Eval pyrolysis along with total organic carbon (TOC) content, organo-micropetrographic framework, thermal maturity, carbon isotopic signature, biomarker composition, functional group studies and estimation of relative aliphaticity and aromaticity through Fourier Transform infrared spectroscopy (FTIR). The novelty of the present work lies in the application of multiple proxies such as stable isotope ratio of organic carbon (delta C-13), biomarker signatures, thermal maturity parameters, organo-micropetrography and estimation and quantification of functional groups for palaeoenvironmental reconstruction and to assess the hydrocarbon productivity of the basin. A dominant terrestrial OM input in Barjora Basin is indicated by the TOC to total nitrogen ratio (C/N), delta C-13 and biomarker compositions. High gelification index (GI), tissue preservation index (TPI), and carbon preference index (CPI) values indicate that coals are deposited in wet swamp forest regime under high rainwater conditions and shales are formed in upper delta plain regime under high groundwater activity. In addition, large liptinite content, TPI and GI designate short transportation of the OM before burial leading to organic richness of the Barjora Basin. Moreover, high liptinite content, type II-III admixed kerogen input, S-2/S-3 ratio, TPI and index for hydrocarbon generation (I-HG) signify higher potential of the basin for hydrocarbon generation.
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| 6. |
- Mörner, Nils-Axel, 1938-
(författare)
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Paleoseismology : The application of multiple parameters in four case studies in Sweden
- 2011
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Ingår i: Quaternary International. - : Elsevier BV. - 1040-6182 .- 1873-4553. ; 242:1, s. 65-75
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Tidskriftsartikel (refereegranskat)abstract
- Many different primary and secondary effects of an earthquake can be used in order to reconstruct and determine a paleoseismic event. In this case we advocate the application of multiple criteria. Four case studies in Sweden are examined; two late-glacial and two Late Holocene events. Special accounts are given of bedrock fracturing away from the primary fault, liquefaction (with multiple phases and structureless sand layers), tsunami, distribution of seabed turbidites, dating by varves, methane venting tectonics and magnetic grain rotation. The multitude of observational data related to all four cases are combined into simple tables where the environmental and spatial effects can be explicitly assessed in terms of documentation, intensity and magnitude. (C) 2011 Elsevier Ltd and INQUA. All rights reserved.
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