SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "hsv:(NATURVETENSKAP) hsv:(Geovetenskap och miljövetenskap) hsv:(Geofysik) ;lar1:(slu)"

Sökning: hsv:(NATURVETENSKAP) hsv:(Geovetenskap och miljövetenskap) hsv:(Geofysik) > Sveriges Lantbruksuniversitet

  • Resultat 1-10 av 20
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Klaminder, Jonatan, et al. (författare)
  • Carbon mineralization and pyrite oxidation in groundwater : Importance for silicate weathering in boreal forest soils and stream base-flow chemistry
  • 2011
  • Ingår i: Applied Geochemistry. - : Elsevier BV. - 0883-2927 .- 1872-9134. ; 26:3, s. 319-324
  • Tidskriftsartikel (refereegranskat)abstract
    • What role does mineralized organic C and sulfide oxidation play in weathering of silicate minerals in deep groundwater aquifers? In this study, how H(2)CO(3), produced as a result of mineralization of organic matter during groundwater transport, affects silicate weathering in the saturated zone of the mineral soil along a 70 m-long boreal hillslope is demonstrated. Stream water measurements of base cations and delta(18)O are included to determine the importance of the deep groundwater system for downstream surface water. The results suggest that H2CO3 generated from organic compounds being mineralized during the lateral transport stimulates weathering at depths between 0.5 and 3 m in the soil. This finding is indicated by progressively increasing concentrations of base cations-, silica- and inorganic C (IC) in the groundwater along the hillslope that co-occur with decreasing organic C (OC) concentrations. Protons derived from sulfide oxidation appear to be an additional driver of the weathering process as indicated by a buildup of SO(4)(2-) in the groundwater during lateral transport and a delta(34)S parts per thousand value of +0.26-3.76 parts per thousand in the deep groundwater indicating S inputs from pyrite. The two identified active acids in the deep groundwater are likely to control the base-flow chemistry of streams draining larger catchments (>1 km(2)) as evident by delta(18)O signatures and base cation concentrations that overlap with that of the groundwater.
  •  
2.
  • Berggren Kleja, Dan, et al. (författare)
  • Characterization of iron in floating surface films of some natural waters using EXAFS
  • 2012
  • Ingår i: Chemical Geology. - : Elsevier. - 0009-2541 .- 1872-6836. ; 326, s. 19-26
  • Tidskriftsartikel (refereegranskat)abstract
    • Floating, iron bearing films have been observed in a wide range of environments, including wetlands, seep waters in ground water discharge areas, small rivers and lakes. To date, knowledge about their formation and composition is scarce. We have investigated the form of iron in floating iron-rich films of different origin, including a pond and a brook, as well as seep water pools of a groundwater discharge area. Sampling sites were located in southern (pond, brook) and central (seep pools) Sweden. Synchrotron-based X-ray absorption spectroscopy (EXAFS and XANES) allowed identification of the iron precipitates present in the films, without any pretreatment. The EXAFS data showed that the iron containing phase formed in the floating films varied in composition between the sites investigated. In the films from two ground water discharge areas, characterized by out-flowing iron(II) rich ground water being high in pH and low in DOC, the iron phase was completely dominated by ferrihydrite. In contrast, surface films sampled from the brook and the pond, the iron speciation showed a mixture of iron(III)-organic complexes and iron (hydr)oxide (most likely ferrihydrite). These waters were oxic and contained higher concentration of DOC than the seep water pools in the ground water discharge areas. The position of the pre-edge peak, which is sensitive to the oxidation state of iron, did not indicate occurrence of iron (II) in any of the films. Elemental composition of one film (seep water), suggested that films contained about one third of organic matter. Ferrihydrite is probably present as small particles with humic material sorbed onto surfaces or included in the particles, making the particles sufficiently hydrophobic to not settle without physical disturbance. The films are fragile and break easily down and become suspended upon disturbance. More studies are warranted in order to understand the mechanism of the formation of these fascinating films and their biogeochemical role.
  •  
3.
  • Campeau, Audrey, et al. (författare)
  • Stable carbon isotopes reveal soil - stream DIC linkages in contrasting headwater catchments
  • 2018
  • Ingår i: Journal of Geophysical Research - Biogeosciences. - : American Geophysical Union (AGU). - 2169-8953 .- 2169-8961. ; 123:1, s. 149-167
  • Tidskriftsartikel (refereegranskat)abstract
    • Large CO2 evasion to the atmosphere occurs as dissolved inorganic carbon (DIC) is transported from soils to streams. While this physical process has been the focus of multiple studies, less is known about the underlying biogeochemical transformations that accompany this transfer of C from soils to streams. Here we used patterns in stream water and groundwater C-13-DIC values within three headwater catchments with contrasting land cover to identify the sources and processes regulating DIC during its transport. We found that although considerable CO2 evasion occurs as DIC is transported from soils to streams, there were also other processes affecting the DIC pool. Methane production and mixing of C sources, associated with different types and spatial distribution of peat-rich areas within each catchment, had a significant influence on the C-13-DIC values in both soils and streams. These processes represent an additional control on C-13-DIC values and the catchment-scale cycling of DIC across different northern landscape types. The results from this study demonstrate that the transport of DIC from soils to streams results in more than just rapid CO2 evasion to the atmosphere but also represents a channel of C transformation, which questions some of our current conceptualizations of C cycling at the landscape scale. Plain Language Summary Large carbon dioxide emission to the atmosphere occurs as rainwater percolates through soils and into streams. This physical process is important for the global carbon cycle and has been the focus of multiple studies. However, less is known about the underlying processes that accompanies this transfer of carbon dioxide from soils to streams. Here we analyze the stable isotope composition of soil and stream carbon dioxide and demonstrate that methane production and mixing of carbon sources also occur in soils and streams. These processes were linked to different types and configurations of peat-rich areas, for example, bogs, fens, and riparian zones, found within each of the three studied catchments. Our results therefore demonstrate that the export of carbon dioxide from soils to streams not only results in emissions to the atmosphere but also represents a channel of transformation. This questions some of our current conceptualization of the catchment-scale cycling of carbon dioxide.
  •  
4.
  • Verheijen, Hendricus, et al. (författare)
  • Magnitude and Origin of CO2 Evasion From High-Latitude Lakes
  • 2022
  • Ingår i: Journal of Geophysical Research - Biogeosciences. - : John Wiley & Sons. - 2169-8953 .- 2169-8961. ; 127:6
  • Tidskriftsartikel (refereegranskat)abstract
    • Lakes evade significant amounts of carbon dioxide (CO2) to the atmosphere; yet the magnitude and origin of the evasion are still poorly constrained. We quantified annual CO2 evasion and its origin (in-lake net ecosystem production vs. lateral inputs from terrestrial ecosystems) in 14 high-latitude lakes through high-frequency estimates of open water CO2 flux and ecosystem metabolism and inorganic carbon mass-balance before and after ice breakup. Annual CO2 evasion ranged from 1 to 25 g C m−2 yr−1 of which an average of 57% was evaded over a short period at ice-breakup. Annual internal CO2 production ranged from −6 to 21 g C m−2 yr−1, of which at least half was produced over winter. The contribution of internal versus external source contribution to annual CO2 evasion varied between lakes, ranging from fully internal to fully external with most lakes having over 75% of the evasion sustained through a single source. Overall, the study stresses the large variability in magnitude and control of CO2 evasion and suggests that environmental change impacts on CO2 evasion from high-latitude lakes are not uniform.
  •  
5.
  • Fischer, R, et al. (författare)
  • Towards a transnational system of supersites for forest monitoring and research in Europe - an overview on present state and future recommendations
  • 2011
  • Ingår i: IForest. - : Italian Society of Sivilculture and Forest Ecology (SISEF). - 1971-7458. ; 4:1, s. 167-171
  • Tidskriftsartikel (refereegranskat)abstract
    • Science based approaches in addressing future risks and challenges for forests require close collaboration among the communities operating different monitoring and research networks as well as experts in process and large-scale modelling. Results of the COST FP0903 conference which took place in October 2010 in Rome, reveal valuable results from different European forest monitoring and research networks. However, the need for closer integration of these activities is obvious. In this paper, representatives from major European networks recommend a new approach for forest monitoring and research in Europe, based on a reasonable number of highly instrumented "supersites" and a larger number of intensive monitoring plots linked to these. This system needs to be built on existing infrastructures but requires increased coordination, harmonisation and a joint long term platform for data exchange and modelling.
  •  
6.
  • Harrysson Drotz, Stina, et al. (författare)
  • Effects of soil organic matter composition on unfrozen water content and heterotrophic CO2 production of frozen soils
  • 2010
  • Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier BV. - 0016-7037 .- 0046-564X. ; 74, s. 2281-2290
  • Tidskriftsartikel (refereegranskat)abstract
    • Several recent studies have highlighted the importance of soil organic matter (SOM) mineralization at high latitudes during winter for ecosystem carbon (C) balances, and the ability of the soil to retain unfrozen water at sub-zero temperatures has been shown to be a major determinant of C mineralization rates. Further, SOM is believed to strongly influence the liquid water contents in frozen surface layers of boreal forest soils and tundra, but the mechanisms and specific factors involved are currently unknown. Here we evaluate the effects of the chemical composition of SUM on the amount of unfrozen water, the pore size equivalents in which unfrozen water can exist, and the microbial heterotrophic activity at sub-zero temperatures in boreal forest soils. To do this, we have characterized the chemical composition of SUM in forest soil samples (surface O-horizons) using solid state CP-MAS (cross polarization magic angle spinning) NMR spectroscopy. The acquired information was then used to elucidate the extent to which different fractions of SUM can explain the observed variations in unfrozen water content, pore size equivalents, and biogenic CO2 production rates in the examined soil samples under frozen conditions (-4 degrees C). The data evaluation was done by the use of principal component analysis (PCA) and projections to latent structures by means of partial least square (PLS). We conclude that aromatic, O-aromatic, methoxy/N-alkyl and alkyl C are the major SOM components affecting frozen boreal forest soil's ability to retain unfrozen water and sustain heterotrophic activity (95% confidence level). Our results reveal that solid carbohydrates have a significant negative impact (95% confidence level) on CO2 production in frozen boreal spruce forest soils, in contrast to the positive effects of carbohydrate polymers during unfrozen conditions. We conclude that the hierarchy of environmental factors controlling SOM mineralization changes as soils freeze. The effect of SUM composition on pore size distribution and unfrozen water content has a superior influence on SUM mineralization and hence on heterotrophic CO2 production of frozen soils. (C) 2010 Elsevier Ltd. All rights reserved.
  •  
7.
  • Huuva, Ivan, et al. (författare)
  • Predictions of Biomass Change in a Hemi-Boreal Forest Based on Multi-Polarization L- and P-Band SAR Backscatter
  • 2020
  • Ingår i: Canadian journal of remote sensing. - : Informa UK Limited. - 0703-8992 .- 1712-7971. ; 46:6, s. 661-680
  • Tidskriftsartikel (refereegranskat)abstract
    • Above-ground biomass change accumulated during four growth seasons in a hemi-boreal forest was predicted using airborne L- and P-band synthetic aperture radar (SAR) backscatter. The radar data were collected in the BioSAR 2007 and BioSAR 2010 campaigns over the Remningstorp test site in southern Sweden. Regression models for biomass change were developed from biomass maps created using airborne LiDAR data and field measurements. To facilitate training and prediction on image pairs acquired at different dates, a backscatter offset correction method for L-band data was developed and evaluated. The correction, based on the HV/VV backscatter ratio, facilitated predictions across image pairs almost identical to those obtained using data from the same image pair for both training and prediction. For P-band, previous positive results using an offset correction based on the HH/VV ratio were validated. The best L-band model achieved a root mean square error (RMSE) of 21 t/ha, and the best P-band model achieved an RMSE of 19 t/ha. Those accuracies are similar to that of the LiDAR-based biomass change of 18 t/ha. The limitation of using LiDAR-based data for training was considered. The findings demonstrate potential for improved biomass change predictions from L-band backscatter despite varying environmental conditions and calibration uncertainties.
  •  
8.
  • Klosterhalfen, Anne (författare)
  • Simulation of spatial variability in crop leaf area index and yield using agroecosystem modeling and geophysics-based quantitative soil information
  • 2020
  • Ingår i: Vadose Zone Journal. - : Wiley. - 1539-1663. ; 19
  • Tidskriftsartikel (refereegranskat)abstract
    • Agroecosystem models that simulate crop growth as a function of weather conditions and soil characteristics are among the most promising tools for improving crop yield and achieving more sustainable agricultural production systems. This study aims at using spatially distributed crop growth simulations to investigate how field-scale patterns in soil properties obtained using geophysical mapping affect the spatial variability of soil water content dynamics and growth of crops at the square kilometer scale. For this, a geophysics-based soil map was intersected with land use information. Soil hydraulic parameters were calculated using pedotransfer functions. Simulations of soil water content dynamics performed with the agroecosystem model AgroC were compared with soil water content measured at two locations, resulting in RMSE of 0.032 and of 0.056 cm(3) cm(-3), respectively. The AgroC model was then used to simulate the growth of sugar beet (Beta vulgaris L.), silage maize (Zea mays L.), potato (Solanum tuberosum L.), winter wheat (Triticum aestivum L.), winter barley (Hordeum vulgare L.), and winter rapeseed (Brassica napus L.) in the 1- by 1-km study area. It was found that the simulated leaf area index (LAI) was affected by the magnitude of simulated water stress, which was a function of both the crop type and soil characteristics. Simulated LAI was generally consistent with the observed LAI calculated from normalized difference vegetation index (LAI(NDVI)) obtained from RapidEye satellite data. Finally, maps of simulated agricultural yield were produced for four crops, and it was found that simulated yield matched well with actual harvest data and literature values. Therefore, it was concluded that the information obtained from geophysics-based soil mapping was valuable for practical agricultural applications.
  •  
9.
  • Stjernman Forsberg, Lovisa, et al. (författare)
  • Effects of sewage sludge on solution chemistry and plant uptake of Cu in sulphide mine tailings at different weathering stages
  • 2009
  • Ingår i: Applied Geochemistry. - : Elsevier BV. - 0883-2927 .- 1872-9134. ; 24:3, s. 475-482
  • Tidskriftsartikel (refereegranskat)abstract
    • This climate chamber experiment examines the effects of sewage sludge (SS) on sulphide mine tailings from the Aitik Cu mine in northern Sweden. The effects of SS were determined from Cu in solution and Cu uptake and growth of plants on tailings showing 3 different degrees of weathering. Possible relationships between Cu content in plants and Cu in solution measured in tailings (total dissolved Cu and free Cu) were also evaluated. Red fescue (Festuca rubra) was grown for 6 weeks in pots of the different tailings treated with SS or NPK fertiliser. Soil solution was sampled with Rhizon tension lysimeters and analysed for pH, dissolved organic C (DOC), free Cu, total dissolved Cu and SO42-. The effects of SS on Cu in solution and plants depended on the degree of weathering. In tailings with a low degree of sulphide oxidation, SS application resulted in increased solubility and shoot accumulation of Cu compared with NPK-treated tailings, probably due to DOC forming soluble complexes with Cu. Sewage sludge also seemed to promote translocation of Cu to shoots in those tailings. In highly weathered tailings, lower contents of total dissolved Cu and free Cu in solution and lower Cu levels in shoots were found in SS-treated samples than in NPK-treated. In the moderately weathered tailings, Cu concentrations in solutions were generally similar between treatments, but lower contents of Cu were found in shoots and roots of the fescue grown in the SS-treatment. Irrespective of degree of weathering and treatment, both free Cu and total dissolved Cu concentration in tailings correlated strongly with Cu levels found in fescue shoots.
  •  
10.
  • Tiberg, Charlotta, et al. (författare)
  • Phosphate effects on copper(II) and lead(II) sorption to ferrihydrite
  • 2013
  • Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier. - 0016-7037 .- 1872-9533 .- 0046-564X. ; 120, s. 140-157
  • Tidskriftsartikel (refereegranskat)abstract
    • Transport of lead(II) and copper(II) ions in soil is affected by the soil phosphorus status. Part of the explanation may be that phosphate increases the adsorption of copper(II) and lead(II) to iron (hydr)oxides in soil, but the details of these interactions are poorly known. Knowledge about such mechanisms is important, for example, in risk assessments of contaminated sites and development of remediation methods. We used a combination of batch experiments, extended X-ray absorption fine structure (EXAFS) spectroscopy and surface complexation modeling with the three-plane CD-MUSIC model to study the effect of phosphate on sorption of copper(II) and lead(II) to ferrihydrite. The aim was to identify the surface complexes formed and to derive constants for the surface complexation reactions. In the batch experiments phosphate greatly enhanced the adsorption of copper(II) and lead(II) to ferrihydrite at pH < 6. The largest effects were seen for lead(II). Based on interpretation of the EXAFS spectra edge-sharing bidentate copper(II) or lead(II) complexes predominated in the single-sorbate systems with ferrihydrite. Lead(II) EXAFS spectra suggested a distinct change of coordination in the presence of phosphate, i.e. the signal from edge-sharing complexes diminished and a longer Pb center dot center dot center dot Fe distance appeared at about 4 angstrom. A similar, but less pronounced, pattern was observed for copper(II). Based on the results from interpretation of EXAFS spectra and surface complexation modeling with the CD-MUSIC model the enhanced sorption in presence of phosphate was most satisfactorily explained by the appearance of ternary metal-phosphate complexes in which the metal interacts directly with the surface. In conclusion, geochemical models used for simulating trace element behavior in acidic environments seem to require ternary metal-phosphate surface complexes to properly describe partitioning of metals between solution and the solid phase.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-10 av 20
Typ av publikation
tidskriftsartikel (16)
konferensbidrag (2)
doktorsavhandling (1)
forskningsöversikt (1)
Typ av innehåll
refereegranskat (19)
övrigt vetenskapligt/konstnärligt (1)
Författare/redaktör
Persson, Henrik (4)
Ulander, Lars, 1962 (4)
Fransson, Johan E.S. (4)
Laudon, Hjalmar (3)
Nilsson, Mats (3)
Persson, Ingmar (2)
visa fler...
Bishop, Kevin (2)
Gustafsson, Jon-Pett ... (2)
Wallerman, Jörgen (2)
Berggren Kleja, Dan (2)
Soja, Maciej, 1985 (2)
Öquist, Mats (2)
Aas, W. (1)
Simpson, David, 1961 (1)
Campeau, Audrey (1)
Wallin, Marcus, 1979 ... (1)
Buffam, Ishi (1)
Peichl, Matthias (1)
Ottosson Löfvenius, ... (1)
Infantes, Eduardo (1)
Wallin, Göran, 1955 (1)
Näsholm, Torgny (1)
Lundin, Lars (1)
Manzoni, Stefano (1)
Lundmark, Tomas (1)
Linder, Sune (1)
Eriksson, Leif, 1970 (1)
Tuovinen, J. P. (1)
Klaminder, Jonatan (1)
Björk, Mats (1)
Fischer, R (1)
Ågren, Anneli (1)
Greger, Maria (1)
Mörth, Carl-Magnus (1)
Gullström, Martin, 1 ... (1)
Asplund, Maria. E., ... (1)
Klemedtsson, Leif (1)
Keller, Thomas (1)
Dahl, Martin (1)
Deyanova, Diana (1)
Franco, Joao N. (1)
Perry, Diana (1)
Sjöstedt, Carin (1)
Marshall, John (1)
Karlsson, Jan, 1974- (1)
Monteith, Albert, 19 ... (1)
Van Schaik, Joris (1)
Verheijen, Hendricus (1)
Grip, Harald (1)
Hörnlund, Thomas (1)
visa färre...
Lärosäte
Chalmers tekniska högskola (5)
Göteborgs universitet (2)
Umeå universitet (2)
Kungliga Tekniska Högskolan (2)
Uppsala universitet (2)
visa fler...
Stockholms universitet (2)
visa färre...
Språk
Engelska (19)
Franska (1)
Forskningsämne (UKÄ/SCB)
Naturvetenskap (20)
Lantbruksvetenskap (12)
Teknik (4)
Samhällsvetenskap (1)

År

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy