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  • 1.
    Becher, Marina
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Olid, Carolina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Klaminder, Jonatan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Buried soil organic inclusions in non-sorted circles fields in northern Sweden: Age and Paleoclimatic context2013Ingår i: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 118, nr 1, s. 104-111Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Although burial of surface organic soil horizons into deeper mineral soil layers helps drive the long-term buildup of carbon in arctic soils, when and why buried horizons formed as result of cryoturbation in northern Sweden remain unclear. In this study, we used C-14 and Pb-210 dating to assess when organic matter was buried within non-sorted circles fields near Abisko in northern Sweden. In addition, we used aerial photos from 1959 and 2008 to detect eventual trends in cryogenic activities during this period. We found that organic matter from former organic horizons (stratigraphically intact or partly fragmented) corresponds to three major periods: 0-100 A. D., 900-1250 A. D., and 1650-1950 A. D. The latter two periods were indicated by several dated samples, while the extent of the oldest period is more uncertainty (indicated by only one sample). The aerial photos suggest a net overgrowth by shrub vegetation of previously exposed mineral soil surfaces since 1959. This overgrowth trend was seen in most of the studied fields (92 out of 137 analyzed fields), indicating that the cryogenic activity has mainly decreased in studied non-sorted circles fields since the 1950s. This latter interpretation is also supported by the absence of buried organic layers formed during the last decades. We suggest that the organic matter was buried during the transition from longer cold periods to warmer conditions. We believe these climatic shifts could have triggered regional scale burial of soil organic matter and thus affected how these soils sequestered carbon.

  • 2.
    Hansson, Sophia V.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Kaste, James M.
    College of William & Mary.
    Olid, Carolina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Bindler, Richard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Incorporation of radiometric tracers in peat and implications for estimating accumulation rates2014Ingår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 493, s. 170-177Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Accurate dating of peat accumulation is essential for quantitatively reconstructing past changes in atmospheric metal deposition and carbon burial. By analyzing fallout radionuclides Pb-210, Cs-137, Am-241, and Be-7, and total Pb and Hg in 5 cores from two Swedish peatlands we addressed the consequence of estimating accumulation rates due to downwashing of atmospherically supplied elements within peat. The detection of Be-7 down to 18-20 cm for some cores, and the broad vertical distribution of Am-241 without a well-defined peak, suggest some downward transport by percolating rainwater and smearing of atmospherically deposited elements in the uppermost peat layers. Application of the CRS age-depth model leads to unrealistic peat mass accumulation rates (400-600 g m(-2) yr(-1)), and inaccurate estimates of past Pb and Hg deposition rates and trends, based on comparisons to deposition monitoring data (forest moss biomonitoring and wet deposition). After applying a newly proposed IP-CRS model that assumes a potential downward transport of Pb-210 through the uppermost peat layers, recent peat accumulation rates (200-300 g m(-2) yr(-1)) comparable to published values were obtained. Furthermore, the rates and temporal trends in Pb and Hg accumulation correspond more closely to monitoring data, although some off-set is still evident. We suggest that downwashing can be successfully traced using Be-7, and if this information is incorporated into age-depth models, better calibration of peat records with monitoring data and better quantitative estimates of peat accumulation and past deposition are possible, although more work is needed to characterize how downwashing may vary between seasons or years.

  • 3.
    Klaminder, Jonatan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Yoo, K.
    Olid, Carolina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Rameback, H.
    Vesterlund, A.
    Using Short-lived Radionuclides to Estimate Rates of Soil Motion in Frost Boils2014Ingår i: Permafrost and Periglacial Processes, ISSN 1045-6740, E-ISSN 1099-1530, Vol. 25, nr 3, s. 184-193Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cryoturbation in high-latitude soils is crucial for the long-term cycling of elements, but the rates of soil motion are poorly constrained. Here, we test whether the rate of frost creep, soil erosion and vertical soil mixing in frost boils can be estimated using short-lived radionuclides (Cs-137 and Pb-210). We find a small-scale variation in Cs-137 and Pb-210 inventories in the lower levels of the eroding regions of frost boils in comparison to the expected depositional sites; hence, the distribution of the radionuclides appears to reflect a lateral transport of atmospheric fallout from the centre of the boil (inner domain) towards the surrounding soil (outer domain). C-14 dating of the soil indicates that fallout of Cs-137 was mobile in the soil and that Pb-210 moved with the soil matrix. A soil creep model and a surface soil erosion model are derived and applied to the lateral and vertical distributions of Pb-210 in the frost boil. Both models predict the expected trajectories of soil motion and provide rates of creep, erosion and mixing at a mm yr(-1) to cm yr(-1) scale. The distribution of Pb-210 provides new insights about the processes and rates of soil mass movement in frost boils, if sound mass-balance models are applied.

  • 4.
    Lundin, E. J.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Klaminder, Jonatan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Bastviken, D.
    Olid, Carolina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Hansson, S. V.
    Karlsson, Jan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Large difference in carbon emission: burial balances between boreal and arctic lakes2015Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, artikel-id 14248Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lakes play an important role in the global carbon (C) cycle by burying C in sediments and emitting CO2 and CH4 to the atmosphere. The strengths and control of these fundamentally different pathways are therefore of interest when assessing the continental C balance and its response to environmental change. In this study, based on new high-resolution estimates in combination with literature data, we show that annual emission: burial ratios are generally ten times higher in boreal compared to subarctic - arctic lakes. These results suggest major differences in lake C cycling between biomes, as lakes in warmer boreal regions emit more and store relatively less C than lakes in colder arctic regions. Such effects are of major importance for understanding climatic feedbacks on the continental C sink - source function at high latitudes. If predictions of global warming and northward expansion of the boreal biome are correct, it is likely that increasing C emissions from high latitude lakes will partly counteract the presumed increasing terrestrial C sink capacity at high latitudes.

  • 5.
    Lundin, Erik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Klaminder, Jonatan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Bastviken, David
    Department of Thematic Studies–Water and Environmental Studies, Linköping University, Linköping, Sweden.
    Olid, Carolina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Hansson, Sophia
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Karlsson, Jan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Strong climate impact on the carbon emission – burial balance inhigh latitude lakesManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Lakes play an important role in the global carbon (C) cycle by burying C in sediments and emitting CO2 and CH4 to the atmosphere. The strengths of these fundamentally different pathways are critical for quantifying effects of lakes upon the climate system. In this study, based on new high-resolution estimates in combination with literature data, we show a generally ten times higher emission:burial ratio in boreal compared to subarctic-arctic lakes. These results suggest a major bioclimatic impact on C cycling in lakes, as lakes in warmer boreal regions emit more and store relatively less C than lakes in colder arctic regions. Thus, our results reveal a previously unforeseen longterm climate feedback: if predictions of the northward expansion of the boreal biome are correct, C emissions of high latitude lakes may increase four-fold, corresponding to 14% of present global lake C evasion to the atmosphere. Such effects are of major importance for understanding feedbacks of climate warming on the continental source-sink function at high latitudes

     

     

  • 6. Mojarrad, Brian Babak
    et al.
    Betterle, Andrea
    Singh, Tanu
    Olid, Carolina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Wörman, Anders
    The Effect of Stream Discharge on Hyporheic Exchange2019Ingår i: Water, ISSN 2073-4441, E-ISSN 2073-4441, Vol. 11, nr 7, artikel-id 1436Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Streambed morphology, streamflow dynamics, and the heterogeneity of streambed sediments critically controls the interaction between surface water and groundwater. The present study investigated the impact of different flow regimes on hyporheic exchange in a boreal stream in northern Sweden using experimental and numerical approaches. Low-, base-, and high-flow discharges were simulated by regulating the streamflow upstream in the study area, and temperature was used as the natural tracer to monitor the impact of the different flow discharges on hyporheic exchange fluxes in stretches of stream featuring gaining and losing conditions. A numerical model was developed using geomorphological and hydrological properties of the stream and was then used to perform a detailed analysis of the subsurface water flow. Additionally, the impact of heterogeneity in sediment permeability on hyporheic exchange fluxes was investigated. Both the experimental and modelling results show that temporally increasing flow resulted in a larger (deeper) extent of the hyporheic zone as well as longer hyporheic flow residence times. However, the result of the numerical analysis is strongly controlled by heterogeneity in sediment permeability. In particular, for homogeneous sediments, the fragmentation of upwelling length substantially varies with streamflow dynamics due to the contribution of deeper fluxes.

  • 7.
    Monteux, Sylvain
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Weedon, James T.
    Blume-Werry, Gesche
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Gavazov, Konstantin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Federal Institute for Forest, Snow and Landscape Research WSL, Lausanne, Switzerland.
    Jassey, Vincent E. J.
    Johansson, Margareta
    Keuper, Frida
    Olid, Carolina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Dorrepaal, Ellen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Long-term in situ permafrost thaw effects on bacterial communities and potential aerobic respiration2018Ingår i: The ISME Journal, ISSN 1751-7362, E-ISSN 1751-7370, Vol. 12, nr 9, s. 2129-2141Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The decomposition of large stocks of soil organic carbon in thawing permafrost might depend on more than climate change-induced temperature increases: indirect effects of thawing via altered bacterial community structure (BCS) or rooting patterns are largely unexplored. We used a 10-year in situ permafrost thaw experiment and aerobic incubations to investigate alterations in BCS and potential respiration at different depths, and the extent to which they are related with each other and with root density. Active layer and permafrost BCS strongly differed, and the BCS in formerly frozen soils (below the natural thawfront) converged under induced deep thaw to strongly resemble the active layer BCS, possibly as a result of colonization by overlying microorganisms. Overall, respiration rates decreased with depth and soils showed lower potential respiration when subjected to deeper thaw, which we attributed to gradual labile carbon pool depletion. Despite deeper rooting under induced deep thaw, root density measurements did not improve soil chemistry-based models of potential respiration. However, BCS explained an additional unique portion of variation in respiration, particularly when accounting for differences in organic matter content. Our results suggest that by measuring bacterial community composition, we can improve both our understanding and the modeling of the permafrost carbon feedback.

  • 8.
    Olid, Carolina
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Bindler, Richard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Mats B.
    Eriksson, Tobias
    Klaminder, Jonatan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Effects of warming and increased nitrogen and sulfur deposition on boreal mire geochemistry2017Ingår i: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 78, s. 149-157Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Boreal mire ecosystems are predicted to experience warmer air temperatures as well as changed deposition loads of nitrogen and sulfur during the coming century. In this study, we hypothesized that vegetation changes that accompany these new environmental conditions alter the chemical composition of peat. To test this hypothesis, we quantified changes in peat geochemistry (Al, Ca, Fe, Mg, Na, P, Pb, and Zn) that have occurred in field manipulation plots exposed to 12 years of warming and nitrogen and sulfur additions in a nutrient-poor boreal mire. In Contrast to non-nutrients with a mainly atmospheric origin (i.e. Pb), Al-normalized inventories of micronutrients (Zn and Fe) and macronutrients (P and Ca) were significantly (P < 0.05) higher as a result of warming. For P and Ca, enrichments were also induced by nitrogen additions alone. These results suggest that mires evolving under increasing temperatures and availability of nitrogen are around two times More effective in storing nutrients in the accumulating peat. Our study provides the first empirical evidence that predicted changes in climate and nitrogen deposition scenarios will increase the retention of Ca, Fe, P, and Zn in surface peat of boreal mires in the near future, which may cause a depletion of nutrients released to inland waters dependent on mire inputs.

  • 9.
    Olid, Carolina
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Diego, David
    Garcia-Orellana, Jordi
    Martinez Cortizas, Antonio
    Klaminder, Jonatan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Modeling the downward transport of Pb-210 in Peatlands: Initial Penetration-Constant Rate of Supply (IP-CRS) model2016Ingår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 541, s. 1222-1231Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The vertical distribution of 210Pb is commonly used to date peat deposits accumulated over the last 100-150 years. However, several studies have questioned this method because of an apparent post-depositional mobility of 210Pb within somepeat profiles. In this study, we introduce the Initial Penetration-Constant Rate of Supply (IP-CRS) model for calculating ages derived from 210Pb profiles that are altered by an initial migration of the radio-nuclide. This new, two-phased, model describes the distribution of atmospheric-derived 210Pb (210Pbxs) in peat taking into account both incorporation of 210Pb into the accumulating peat matrix as well as an initial flushing of 210Pb through the uppermost peat layers. The validity of the IP-CRS model is tested in four anomalous 210Pb peat records that showed some deviations from the typical exponential decay profile not explained by variations in peat accumulation rates. Unlike the most commonly used210Pb-dating model (Constant Rate of Supply (CRS)), the IP-CRS model estimates peat accumulation rates consistent with typical growth rates for peatlands from the same areas. Confidence in the IP-CRS chronology is also provided by the good agreement with independent chronological markers (i.e. 241Am and 137Cs). Our results showed that the IP-CRS can provide chronologies from peat records where 210Pb mobility is evident, being a valuable tool for studies reconstructing past environmental changes using peat archives during the Anthropocene.

  • 10.
    Olid, Carolina
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Garcia-Orellana, Jordi
    Masque, Pere
    Martinez Cortizas, Antonio
    Albert Sanchez-Cabeza, Joan
    Bindler, Richard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Improving the Pb-210-chronology of Pb deposition in peat cores from Chao de Lamoso (NW Spain)2013Ingår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 443, s. 597-607Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The natural radionuclide Pb-210 is commonly used to establish accurate and precise chronologies for the recent (past 100-150 years) layers of peat deposits. The most widely used Pb-210-dating model, Constant Rate of Supply (CRS), was applied using data from three peat cores from Chao de Lamoso, an ombrotrophic mire in Galicia (NW Spain). On the basis of the CRS-chronologies, maximum Pb concentrations and enrichment factors (EFs) occurred in the 1960s and late 1970s, consistent with the historical use of Pb. However, maximum Pb fluxes were dated in the 1940s and the late 1960s, 10 to 20 years earlier. Principal component analysis (PCA) showed that, although the Pb-210 distribution was mainly (74%) controlled by radioactive decay, about 20% of the Pb-210 flux variability was associated with atmospheric metal pollution, suggesting an extra Pb-210 supply source and thus invalidating the main assumption of the CRS model. When the CRS-ages were recalculated after correcting for the extra input from the Pb-210 inventory of the uppermost peat layers of each core, Pb flux variations were consistent with the historical atmospheric Pb deposition. Our results not only show the robustness of the CRS model to establish accurate chronologies of recent peat deposits but also provide evidence that there are confounding factors that might influence the calculation of reliable peat accumulation rates (and thus also element accumulation rates/fluxes). This study emphasizes the need to verify the hypotheses of Pb-210-dating models and the usefulness of a full geochemical interpretation of peat bog records.

  • 11.
    Olid, Carolina
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Mats B.
    Department of Forest and Management, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Eriksson, Tobias
    Department of Forest and Management, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Klaminder, Jonatan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    The effects of temperature and nitrogen and sulfur additions on carbon accumulation in a nutrient-poor boreal mire: decadal effects assessed using 210Pb peat chronologies2014Ingår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, Vol. 119, nr 3, s. 392-402Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Boreal peatlands are a major long-term reservoir of atmospheric carbon (C) and play an important role in the global C cycle. It is unclear how C accumulation in peatlands responds to changing temperatures and nutrients (specifically, nitrogen and sulfur). In this study, we assessed how the C input rate and C accumulation rate in decadal old peat layers respond to increased air temperatures (+3.6 degrees C) during the growing season and the annual additions of nitrogen (N) and sulfur (S) (30 and 20kgha(-1)yr(-1), respectively) over 12years of field treatments in a boreal mire. An empirical mass balance model was applied to Pb-210-dated peat cores to evaluate changes in C inputs, C mass loss, and net C accumulation rates in response to the treatments. We found that (i) none of the treatments generated a significant effect on peat mass loss decay rates, (ii) C input rates were positively affected by N additions and negatively affected by S additions, (iii) the C accumulation rate in the uppermost (10 to 12cm) peat was increased by N additions and decreased by S additions, and (iv) only air temperature significantly affected the main effects induced by N and S additions. Based on our findings, we argue that C accumulation rates in surface peat layers of nutrient-poor boreal mires can increase despite the predicted rise in air temperatures as long as N loads increase and acid atmospheric S remains low. Key Points <list list-type="bulleted" id="jgrg20166-list-0001"> <list-item id="jgrg20166-li-0001">C accumulation in nutrient-poor boreal peatlands is increased by N fertilization <list-item id="jgrg20166-li-0002">Weak effects on C accumulation induced by greenhouse warming

  • 12.
    Sanchez-Cabeza, Joan-Albert
    et al.
    Univ Nacl Autonoma Mexico, Inst Ciencias Mar & Limnol, Dept Proc Ocean & Costeros, Mexico City 04510, DF, Mexico.
    Carolina Ruiz-Fernandez, Ana
    Feliciano Ontiveros-Cuadras, Jorge
    Univ Nacl Autonoma Mexico, Posgrad Ciencias Mar & Limnol, Mazatlan 82040, Mexico.
    Perez Bernal, Libia Hascibe
    Univ Nacl Autonoma Mexico, Inst Ciencias Mar & Limnol, Unidad Acad Mazatlan, Mazatlan 82040, Mexico.
    Olid, Carolina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Monte Carlo uncertainty calculation of Pb-210 chronologies and accumulation rates of sediments and peat bogs2014Ingår i: Quaternary Geochronology, ISSN 1871-1014, E-ISSN 1878-0350, Vol. 23, s. 80-93Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Pb-210 dating is a key technique to study sedimentary records of environmental change in the Anthropocene over a time scale of 100-150 years. Uncertainty estimation of Pb-210 ages and accumulation rates, when provided by the authors, are usually based on quadratic propagation of uncertainties. In this work, we describe the use of Monte Carlo simulation to estimate Pb-210 dating uncertainties in sediment and peat cores. The methodology allows, by using nowadays common computers, the assessment of Pb-210 dating uncertainties in a simple manner, using readily-accessible computers and widely-used proprietary spreadsheet software, and avoiding the derivation of rather complex formulae. Results were calculated and compared with quadratic propagation uncertainties in a marine, lacustrine and peat bog core. The analysis of the uncertainty budgets indicated that, overall, the total and unsupported (or base) (210)pb concentrations are the largest contributors to uncertainty, as well as the layer depths when sediment accumulation rates were calculated. Beyond Pb-210 dating, the Monte Carlo scheme described here could be used in any field of the analytical sciences, including other radiochronological applications. 

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