Articles | Volume 11, issue 12
https://doi.org/10.5194/bg-11-3369-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/bg-11-3369-2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Research article
| 
24 Jun 2014
Research article |
| 24 Jun 2014
Degradation changes stable carbon isotope depth profiles in palsa peatlands
J. P. Krüger
Environmental Geosciences, University of Basel, Basel, Switzerland
J. Leifeld
Agroscope Reckenholz-Tänikon Research Station ART, Zürich, Switzerland
C. Alewell
Environmental Geosciences, University of Basel, Basel, Switzerland
Related authors
J. P. Krüger, J. Leifeld, S. Glatzel, S. Szidat, and C. Alewell
Biogeosciences, 12, 2861–2871, https://doi.org/10.5194/bg-12-2861-2015, https://doi.org/10.5194/bg-12-2861-2015, 2015
Short summary
Short summary
Biogeochemical soil parameters are studied to detect peatland degradation along a land use gradient (intensive, extensive, near-natural). Stable carbon isotopes, radiocarbon ages and ash content confirm peat growth in the near-natural bog but also indicate previous degradation. When the bog is managed extensively or intensively as grassland, all parameters indicate degradation and substantial C loss of the order of 18.8 to 42.9 kg C m-2.
Gerald Dicen, Floriane Guillevic, Surya Gupta, Pierre-Alexis Chaboche, Katrin Meusburger, Pierre Sabatier, Olivier Evrard, and Christine Alewell
Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2024-509, https://doi.org/10.5194/essd-2024-509, 2024
Preprint under review for ESSD
Short summary
Short summary
Fallout radionuclides such as 137Cs and 239+240Pu are considered as critical tools in various environmental research. Here, we compiled reference soil data on these fallout radionuclides from the literature to build a comprehensive database. Using this database, we determined the distribution and sources of 137Cs and 239+240Pu. We also demonstrated how the database can be used to identify the environmental factors that influence their distribution using a machine-learning algorithm.
Katrin Meusburger, Paolo Porto, Judith Kobler Waldis, and Christine Alewell
SOIL, 9, 399–409, https://doi.org/10.5194/soil-9-399-2023, https://doi.org/10.5194/soil-9-399-2023, 2023
Short summary
Short summary
Quantifying soil redistribution rates is a global challenge. Radiogenic tracers such as plutonium, namely 239+240Pu, released to the atmosphere by atmospheric bomb testing in the 1960s are promising tools to quantify soil redistribution. Direct validation of 239+240Pu as soil redistribution is, however, still missing. Here, we used a unique sediment yield time series in southern Italy, reaching back to the initial fallout of 239+240Pu to verify 239+240Pu as a soil redistribution tracer.
Pedro V. G. Batista, Peter Fiener, Simon Scheper, and Christine Alewell
Hydrol. Earth Syst. Sci., 26, 3753–3770, https://doi.org/10.5194/hess-26-3753-2022, https://doi.org/10.5194/hess-26-3753-2022, 2022
Short summary
Short summary
Patchy agricultural landscapes have a large number of small fields, which are separated by linear features such as roads and field borders. When eroded sediments are transported out of the agricultural fields by surface runoff, these features can influence sediment connectivity. By use of measured data and a simulation model, we demonstrate how a dense road network (and its drainage system) facilitates sediment transport from fields to water courses in a patchy Swiss agricultural catchment.
Brieuc Hardy, Nils Borchard, and Jens Leifeld
SOIL, 8, 451–466, https://doi.org/10.5194/soil-8-451-2022, https://doi.org/10.5194/soil-8-451-2022, 2022
Short summary
Short summary
Soil amendment with artificial black carbon (BC; biomass transformed by incomplete combustion) has the potential to mitigate climate change. Nevertheless, the accurate quantification of BC in soil remains a critical issue. Here, we successfully used dynamic thermal analysis (DTA) to quantify centennial BC in soil. We demonstrate that DTA is largely under-exploited despite providing rapid and low-cost quantitative information over the range of soil organic matter.
Lena Wohlgemuth, Pasi Rautio, Bernd Ahrends, Alexander Russ, Lars Vesterdal, Peter Waldner, Volkmar Timmermann, Nadine Eickenscheidt, Alfred Fürst, Martin Greve, Peter Roskams, Anne Thimonier, Manuel Nicolas, Anna Kowalska, Morten Ingerslev, Päivi Merilä, Sue Benham, Carmen Iacoban, Günter Hoch, Christine Alewell, and Martin Jiskra
Biogeosciences, 19, 1335–1353, https://doi.org/10.5194/bg-19-1335-2022, https://doi.org/10.5194/bg-19-1335-2022, 2022
Short summary
Short summary
Gaseous mercury is present in the atmosphere all over the globe. During the growing season, plants take up mercury from the air in a similar way as CO2. We investigated which factors impact this vegetational mercury uptake by analyzing a large dataset of leaf mercury uptake rates of trees in Europe. As a result, we conclude that mercury uptake is foremost controlled by tree-intrinsic traits like physiological activity but also by climatic factors like dry conditions in the air and in soils.
Lauren Zweifel, Maxim Samarin, Katrin Meusburger, and Christine Alewell
Nat. Hazards Earth Syst. Sci., 21, 3421–3437, https://doi.org/10.5194/nhess-21-3421-2021, https://doi.org/10.5194/nhess-21-3421-2021, 2021
Short summary
Short summary
Mountainous grassland areas can be severely affected by soil erosion, such as by shallow landslides. With an automated mapping approach we are able to locate shallow-landslide sites on aerial images for 10 different study sites across Swiss mountain regions covering a total of 315 km2. Using a statistical model we identify important explanatory variables for shallow-landslide occurrence for the individual sites as well as across all regions, which highlight slope, aspect and terrain roughness.
Maral Khodadadi, Christine Alewell, Mohammad Mirzaei, Ehssan Ehssan-Malahat, Farrokh Asadzadeh, Peter Strauss, and Katrin Meusburger
SOIL Discuss., https://doi.org/10.5194/soil-2021-2, https://doi.org/10.5194/soil-2021-2, 2021
Revised manuscript not accepted
Short summary
Short summary
Forest soils store carbon and therefore play an important role in mitigating climate change impacts. Yet again, deforestation for farming and grazing purposes has grown rapidly over the last decades. Thus, its impacts on soil erosion and soil quality should be understood in order to adopt sustainable management measures. The results of this study indicated that deforestation can prompt soil loss by multiple orders of magnitude and deteriorate the soil quality in both topsoil and subsoil.
Claudia Mignani, Jörg Wieder, Michael A. Sprenger, Zamin A. Kanji, Jan Henneberger, Christine Alewell, and Franz Conen
Atmos. Chem. Phys., 21, 657–664, https://doi.org/10.5194/acp-21-657-2021, https://doi.org/10.5194/acp-21-657-2021, 2021
Short summary
Short summary
Most precipitation above land starts with ice in clouds. It is promoted by extremely rare particles. Some ice-nucleating particles (INPs) cause cloud droplets to already freeze above −15°C, a temperature at which many clouds begin to snow. We found that the abundance of such INPs among other particles of similar size is highest in precipitating air masses and lowest when air carries desert dust. This brings us closer to understanding the interactions between land, clouds, and precipitation.
Lena Wohlgemuth, Stefan Osterwalder, Carl Joseph, Ansgar Kahmen, Günter Hoch, Christine Alewell, and Martin Jiskra
Biogeosciences, 17, 6441–6456, https://doi.org/10.5194/bg-17-6441-2020, https://doi.org/10.5194/bg-17-6441-2020, 2020
Short summary
Short summary
Mercury uptake by trees from the air represents an important but poorly quantified pathway in the global mercury cycle. We determined mercury uptake fluxes by leaves and needles at 10 European forests which were 4 times larger than mercury deposition via rainfall. The amount of mercury taken up by leaves and needles depends on their age and growing height on the tree. Scaling up our measurements to the forest area of Europe, we estimate that each year 20 t of mercury is taken up by trees.
Miriam Groß-Schmölders, Pascal von Sengbusch, Jan Paul Krüger, Kristy Klein, Axel Birkholz, Jens Leifeld, and Christine Alewell
SOIL, 6, 299–313, https://doi.org/10.5194/soil-6-299-2020, https://doi.org/10.5194/soil-6-299-2020, 2020
Short summary
Short summary
Degradation turns peatlands into a source of CO2. There is no cost- or time-efficient method available for indicating peatland hydrology or the success of restoration. We found that 15N values have a clear link to microbial communities and degradation. We identified trends in natural, drained and rewetted conditions and concluded that 15N depth profiles can act as a reliable and efficient tool for obtaining information on current hydrology, restoration success and drainage history.
Pranav Hirave, Guido L. B. Wiesenberg, Axel Birkholz, and Christine Alewell
Biogeosciences, 17, 2169–2180, https://doi.org/10.5194/bg-17-2169-2020, https://doi.org/10.5194/bg-17-2169-2020, 2020
Short summary
Short summary
Sediment input into water bodies is a prominent threat to freshwater ecosystems. We tested the stability of tracers employed in freshwater sediment tracing based on compound-specific isotope analysis during early degradation in soil. While bulk δ13C values showed no stability, δ13C values of plant-derived fatty acids and n-alkanes were stably transferred to the soil without soil particle size dependency after an early degradation in organic horizons, thus indicating their suitability as tracers.
Marlène Lavrieux, Axel Birkholz, Katrin Meusburger, Guido L. B. Wiesenberg, Adrian Gilli, Christian Stamm, and Christine Alewell
Biogeosciences, 16, 2131–2146, https://doi.org/10.5194/bg-16-2131-2019, https://doi.org/10.5194/bg-16-2131-2019, 2019
Short summary
Short summary
A fingerprinting approach using compound-specific stable isotopes was applied to a lake sediment core to reconstruct erosion processes over the past 150 years in a Swiss catchment. Even though the reconstruction of land use and eutrophication history was successful, the observation of comparatively low δ13C values of plant-derived fatty acids in the sediment suggests their alteration within the lake. Thus, their use as a tool for source attribution in sediment cores needs further investigation.
Claudia Mignani, Jessie M. Creamean, Lukas Zimmermann, Christine Alewell, and Franz Conen
Atmos. Chem. Phys., 19, 877–886, https://doi.org/10.5194/acp-19-877-2019, https://doi.org/10.5194/acp-19-877-2019, 2019
Short summary
Short summary
A snow crystal can be generated from an ice nucleating particle or from an ice splinter. In this study we made use of the fact that snow crystals with a particular shape (dendrites) grow within a narrow temperature range (−12 to −17 °C) and can be analysed individually for the presence of an ice nucleating particle. Our direct approach revealed that only one in eight crystals contained such a particle and was of primary origin. The other crystals must have grown from ice splinters.
Cédric Bader, Moritz Müller, Rainer Schulin, and Jens Leifeld
Biogeosciences, 15, 703–719, https://doi.org/10.5194/bg-15-703-2018, https://doi.org/10.5194/bg-15-703-2018, 2018
Short summary
Short summary
When drained, peatlands degrade and release large quantities of CO2, thereby contributing to global warming. Do land use or the chemical composition of peat control the rate of that release? We studied 21 sites from the temperate climate zone managed as croplands, grasslands, or forests and found that the CO2 release was high, but only slightly influenced by land use or peat composition. Hence, only keeping peatlands in their natural state prevents them from becoming strong CO2 sources.
Laura Arata, Katrin Meusburger, Alexandra Bürge, Markus Zehringer, Michael E. Ketterer, Lionel Mabit, and Christine Alewell
SOIL, 3, 113–122, https://doi.org/10.5194/soil-3-113-2017, https://doi.org/10.5194/soil-3-113-2017, 2017
Emiliano Stopelli, Franz Conen, Caroline Guilbaud, Jakob Zopfi, Christine Alewell, and Cindy E. Morris
Biogeosciences, 14, 1189–1196, https://doi.org/10.5194/bg-14-1189-2017, https://doi.org/10.5194/bg-14-1189-2017, 2017
Short summary
Short summary
Based on the analysis of precipitation collected at high altitude, this study provides a relevant advancement in the assessment of the major factors responsible for the abundance and variability of airborne bacterial cells and Pseudomonas syringae in relation to ice nucleators. This is of prime importance to obtain a better understanding of the impact of ice-nucleation-active organisms on the development of precipitation and to determine the dispersal potential of airborne microorganisms.
Simon Schmidt, Christine Alewell, Panos Panagos, and Katrin Meusburger
Hydrol. Earth Syst. Sci., 20, 4359–4373, https://doi.org/10.5194/hess-20-4359-2016, https://doi.org/10.5194/hess-20-4359-2016, 2016
Short summary
Short summary
We present novel research on the seasonal dynamics of the impact of rainfall (R-factor) on the mobilization of topsoil as soil erosion by water for Switzerland. A modeling approach was chosen that enables the dynamical mapping of the R-factor. Based on the maps and modeling results, we could investigate the spatial and temporal distribution of that factor, which is high for Switzerland. With these results, agronomists can introduce selective erosion control measures.
Emiliano Stopelli, Franz Conen, Cindy E. Morris, Erik Herrmann, Stephan Henne, Martin Steinbacher, and Christine Alewell
Atmos. Chem. Phys., 16, 8341–8351, https://doi.org/10.5194/acp-16-8341-2016, https://doi.org/10.5194/acp-16-8341-2016, 2016
Short summary
Short summary
Knowing the variability of ice nucleating particles (INPs) helps determining their role in the formation of precipitation. Here we describe and predict the concentrations of INPs active at −8 °C in precipitation samples collected at Jungfraujoch (CH, 3580 m a.s.l.). A high abundance of these INPs can be expected whenever a coincidence of high wind speed and first precipitation from an air mass occurs. This expands the set of conditions where such INPs could affect the onset of precipitation.
Lorenzo Menichetti, Thomas Kätterer, and Jens Leifeld
Biogeosciences, 13, 3003–3019, https://doi.org/10.5194/bg-13-3003-2016, https://doi.org/10.5194/bg-13-3003-2016, 2016
Short summary
Short summary
Soil organic carbon dynamics are crucial for the global greenhouse gas balance, but their complexity is difficult to model and understand. We therefore often rely on radiocarbon measurements for calibrating models, but their effect on our understanding of the processes is still unclear. We calibrated five model structures on data from a long-term Swiss field experiment in a Bayesian framework to assess the effect of radiocarbon on the parameter and structural uncertainty of a soil carbon model.
Christine Alewell, Axel Birkholz, Katrin Meusburger, Yael Schindler Wildhaber, and Lionel Mabit
Biogeosciences, 13, 1587–1596, https://doi.org/10.5194/bg-13-1587-2016, https://doi.org/10.5194/bg-13-1587-2016, 2016
Short summary
Short summary
Origin of suspended sediments in rivers is of crucial importance for optimization of catchment management. Sediment source attribution to a lowland river in central Switzerland with compound specific stable isotopes analysis (CSIA) indicated that 65 % of the suspended sediments originated from agricultural land during base flow, while forest was the dominant source during high flow. We achieved significant differences in CSIA signature from land uses dominated by C3 plant cultivation.
S. Osterwalder, J. Fritsche, C. Alewell, M. Schmutz, M. B. Nilsson, G. Jocher, J. Sommar, J. Rinne, and K. Bishop
Atmos. Meas. Tech., 9, 509–524, https://doi.org/10.5194/amt-9-509-2016, https://doi.org/10.5194/amt-9-509-2016, 2016
Short summary
Short summary
Human activities have increased mercury (Hg) cycling between land and atmosphere. To define landscapes as sinks or sources of Hg we have developed an advanced REA system for long-term measurements of gaseous elemental Hg exchange. It was tested in two contrasting environments: above Basel, Switzerland, and a peatland in Sweden. Both landscapes showed net Hg emission (15 and 3 ng m−2 h−1, respectively). The novel system will help to advance our understanding of Hg exchange on an ecosystem scale.
R. Hüppi, R. Felber, A. Neftel, J. Six, and J. Leifeld
SOIL, 1, 707–717, https://doi.org/10.5194/soil-1-707-2015, https://doi.org/10.5194/soil-1-707-2015, 2015
Short summary
Short summary
Biochar is considered an opportunity to tackle major environmental issues in agriculture. Adding pyrolised organic residues to soil may sequester carbon, increase yields and reduce nitrous oxide emissions from soil. It is unknown, whether the latter is induced by changes in soil pH. We show that biochar application substantially reduces nitrous oxide emissions from a temperate maize cropping system. However, the reduction was only achieved with biochar but not with liming.
J. Leifeld and J. Mayer
SOIL, 1, 537–542, https://doi.org/10.5194/soil-1-537-2015, https://doi.org/10.5194/soil-1-537-2015, 2015
Short summary
Short summary
We present 14C data for field replicates of a controlled agricultural long-term experiment. We show that 14C variability is, on average, 12 times that of the analytical precision of the 14C measurement. Experimental 14C variability is related to neither management nor soil depth. Application of a simple carbon turnover model reveals that experimental variability of radiocarbon results in higher absolute uncertainties of estimated carbon turnover time for deeper soil layers.
J. P. Krüger, J. Leifeld, S. Glatzel, S. Szidat, and C. Alewell
Biogeosciences, 12, 2861–2871, https://doi.org/10.5194/bg-12-2861-2015, https://doi.org/10.5194/bg-12-2861-2015, 2015
Short summary
Short summary
Biogeochemical soil parameters are studied to detect peatland degradation along a land use gradient (intensive, extensive, near-natural). Stable carbon isotopes, radiocarbon ages and ash content confirm peat growth in the near-natural bog but also indicate previous degradation. When the bog is managed extensively or intensively as grassland, all parameters indicate degradation and substantial C loss of the order of 18.8 to 42.9 kg C m-2.
K. Meusburger, G. Leitinger, L. Mabit, M. H. Mueller, A. Walter, and C. Alewell
Hydrol. Earth Syst. Sci., 18, 3763–3775, https://doi.org/10.5194/hess-18-3763-2014, https://doi.org/10.5194/hess-18-3763-2014, 2014
J. Leifeld, C. Bader, E. Borraz, M. Hoffmann, M. Giebels, M. Sommer, and J. Augustin
Biogeosciences Discuss., https://doi.org/10.5194/bgd-11-12341-2014, https://doi.org/10.5194/bgd-11-12341-2014, 2014
Revised manuscript not accepted
S. Stanchi, M. Freppaz, E. Ceaglio, M. Maggioni, K. Meusburger, C. Alewell, and E. Zanini
Nat. Hazards Earth Syst. Sci., 14, 1761–1771, https://doi.org/10.5194/nhess-14-1761-2014, https://doi.org/10.5194/nhess-14-1761-2014, 2014
E. Stopelli, F. Conen, L. Zimmermann, C. Alewell, and C. E. Morris
Atmos. Meas. Tech., 7, 129–134, https://doi.org/10.5194/amt-7-129-2014, https://doi.org/10.5194/amt-7-129-2014, 2014
K. Meusburger, L. Mabit, J.-H. Park, T. Sandor, and C. Alewell
Biogeosciences, 10, 5627–5638, https://doi.org/10.5194/bg-10-5627-2013, https://doi.org/10.5194/bg-10-5627-2013, 2013
K. Meusburger, G. Leitinger, L. Mabit, M. H. Mueller, and C. Alewell
Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hessd-10-9505-2013, https://doi.org/10.5194/hessd-10-9505-2013, 2013
Preprint withdrawn
M. H. Mueller, R. Weingartner, and C. Alewell
Hydrol. Earth Syst. Sci., 17, 1661–1679, https://doi.org/10.5194/hess-17-1661-2013, https://doi.org/10.5194/hess-17-1661-2013, 2013
Related subject area
Biogeochemistry: Wetlands
Assessing root–soil interactions in wetland plants: root exudation and radial oxygen loss
Technical note: Comparison of radiometric techniques for estimating recent organic carbon sequestration rates in inland wetland soils
Shoulder season controls on methane emissions from a boreal peatland
Patterns and drivers of organic matter decomposition in peatland open-water pools
Spatial patterns of organic matter content in the surface soil of the salt marshes of the Venice Lagoon (Italy)
Decomposing the Tea Bag Index and finding slower organic matter loss rates at higher elevations and deeper soil horizons in a minerogenic salt marsh
Sorption of colored vs. noncolored organic matter by tidal marsh soils
From the Top: Surface-derived Carbon Fuels Greenhouse Gas Production at Depth in a Neotropical Peatland
Peatland evaporation across hemispheres: contrasting controls and sensitivity to climate warming driven by plant functional types
Reviews and Syntheses: Variable Inundation Across Earth’s Terrestrial Ecosystems
Driving and limiting factors of CH4 and CO2 emissions from coastal brackish-water wetlands in temperate regions
Reviews and syntheses: Greenhouse gas emissions from drained organic forest soils – synthesizing data for site-specific emission factors for boreal and cool temperate regions
Reviews and syntheses: Understanding the impacts of peatland catchment management on dissolved organic matter concentration and treatability
Plant mercury accumulation and litter input to a Northern Sedge-dominated Peatland
Warming accelerates belowground litter turnover in salt marshes – insights from a Tea Bag Index study
Sedimentary blue carbon dynamics based on chronosequential observations in a tropical restored mangrove forest
Duration of extraction determines CO2 and CH4 emissions from an actively extracted peatland in eastern Quebec, Canada
Nutrient release and flux dynamics of CO2, CH4, and N2O in a coastal peatland driven by actively induced rewetting with brackish water from the Baltic Sea
Quantification of blue carbon in salt marshes of the Pacific coast of Canada
Cutting peatland CO2 emissions with water management practices
Tracking vegetation phenology of pristine northern boreal peatlands by combining digital photography with CO2 flux and remote sensing data
Dissolved organic matter concentration and composition discontinuity at the peat–pool interface in a boreal peatland
Effects of brackish water inflow on methane-cycling microbial communities in a freshwater rewetted coastal fen
High peatland methane emissions following permafrost thaw: enhanced acetoclastic methanogenesis during early successional stages
Origin, transport, and retention of fluvial sedimentary organic matter in South Africa's largest freshwater wetland, Mkhuze Wetland System
Peat macropore networks – new insights into episodic and hotspot methane emission
Mangrove sediment organic carbon storage and sources in relation to forest age and position along a deltaic salinity gradient
Plant genotype controls wetland soil microbial functioning in response to sea-level rise
Soil greenhouse gas fluxes from tropical coastal wetlands and alternative agricultural land uses
Carbon balance of a Finnish bog: temporal variability and limiting factors based on 6 years of eddy-covariance data
High-resolution induced polarization imaging of biogeochemical carbon turnover hotspots in a peatland
Committed and projected future changes in global peatlands – continued transient model simulations since the Last Glacial Maximum
Factors controlling Carex brevicuspis leaf litter decomposition and its contribution to surface soil organic carbon pool at different water levels
Exploring constraints on a wetland methane emission ensemble (WetCHARTs) using GOSAT observations
Global peatland area and carbon dynamics from the Last Glacial Maximum to the present – a process-based model investigation
Vascular plants affect properties and decomposition of moss-dominated peat, particularly at elevated temperatures
Denitrification and associated nitrous oxide and carbon dioxide emissions from the Amazonian wetlands
Drivers of seasonal- and event-scale DOC dynamics at the outlet of mountainous peatlands revealed by high-frequency monitoring
Comparison of eddy covariance CO2 and CH4 fluxes from mined and recently rewetted sections in a northwestern German cutover bog
Microtopography is a fundamental organizing structure of vegetation and soil chemistry in black ash wetlands
Interacting effects of vegetation components and water level on methane dynamics in a boreal fen
Low methane emissions from a boreal wetland constructed on oil sand mine tailings
Evidence for preferential protein depolymerization in wetland soils in response to external nitrogen availability provided by a novel FTIR routine
Saltwater reduces potential CO2 and CH4 production in peat soils from a coastal freshwater forested wetland
Reviews and syntheses: Greenhouse gas exchange data from drained organic forest soils – a review of current approaches and recommendations for future research
Effects of sterilization techniques on chemodenitrification and N2O production in tropical peat soil microcosms
Modelling long-term blanket peatland development in eastern Scotland
Cushion bogs are stronger carbon dioxide net sinks than moss-dominated bogs as revealed by eddy covariance measurements on Tierra del Fuego, Argentina
Humic surface waters of frozen peat bogs (permafrost zone) are highly resistant to bio- and photodegradation
Multi-year methane ebullition measurements from water and bare peat surfaces of a patterned boreal bog
Katherine A. Haviland and Genevieve L. Noyce
Biogeosciences, 21, 5185–5198, https://doi.org/10.5194/bg-21-5185-2024, https://doi.org/10.5194/bg-21-5185-2024, 2024
Short summary
Short summary
Plant roots release both oxygen and carbon to the surrounding soil. While oxygen leads to less production of methane (a greenhouse gas), carbon often has the opposite effect. We investigated these processes in two plant species, S. patens and S. americanus. We found that S. patens roots produce more carbon and less oxygen than S. americanus. Additionally, the S. patens pool of root-associated carbon compounds was more dominated by compound types known to lead to higher methane production.
Purbasha Mistry, Irena F. Creed, Charles G. Trick, Eric Enanga, and David A. Lobb
Biogeosciences, 21, 4699–4715, https://doi.org/10.5194/bg-21-4699-2024, https://doi.org/10.5194/bg-21-4699-2024, 2024
Short summary
Short summary
Precise and accurate estimates of wetland organic carbon sequestration rates are crucial to track the progress of climate action goals through effective carbon budgeting. Radioisotope dating methods using cesium-137 (137Cs) and lead-210 (210Pb) are needed to provide temporal references for these estimations. The choice between using 137Cs or 210Pb, or their combination, depends on respective study objectives, with careful consideration of factors such as dating range and estimation complexity.
Katharina Jentzsch, Elisa Männistö, Maija E. Marushchak, Aino Korrensalo, Lona van Delden, Eeva-Stiina Tuittila, Christian Knoblauch, and Claire C. Treat
Biogeosciences, 21, 3761–3788, https://doi.org/10.5194/bg-21-3761-2024, https://doi.org/10.5194/bg-21-3761-2024, 2024
Short summary
Short summary
During cold seasons, methane release from northern wetlands is important but often underestimated. We studied a boreal bog to understand methane emissions in spring and fall. At cold temperatures, methane release decreases due to lower production rates, but efficient methane transport through plant structures, decaying plants, and the release of methane stored in the pore water keep emissions ongoing. Understanding these seasonal processes can improve models for methane release in cold climates.
Julien Arsenault, Julie Talbot, Tim R. Moore, Klaus-Holger Knorr, Henning Teickner, and Jean-François Lapierre
Biogeosciences, 21, 3491–3507, https://doi.org/10.5194/bg-21-3491-2024, https://doi.org/10.5194/bg-21-3491-2024, 2024
Short summary
Short summary
Peatlands are among the largest carbon (C) sinks on the planet. However, peatland features such as open-water pools emit more C than they accumulate because of higher decomposition than production. With this study, we show that the rates of decomposition vary among pools and are mostly driven by the environmental conditions in pools rather than by the nature of the material being decomposed. This means that changes in pool number or size may modify the capacity of peatlands to accumulate C.
Alice Puppin, Davide Tognin, Massimiliano Ghinassi, Erica Franceschinis, Nicola Realdon, Marco Marani, and Andrea D'Alpaos
Biogeosciences, 21, 2937–2954, https://doi.org/10.5194/bg-21-2937-2024, https://doi.org/10.5194/bg-21-2937-2024, 2024
Short summary
Short summary
This study aims at inspecting organic matter dynamics affecting the survival and carbon sink potential of salt marshes, which are valuable yet endangered wetland environments. Measuring the organic matter content in marsh soils and its relationship with environmental variables, we observed that the organic matter accumulation varies at different scales, and it is driven by the interplay between sediment supply and vegetation, which are affected, in turn, by marine and fluvial influences.
Satyatejas G. Reddy, W. Reilly Farrell, Fengrun Wu, Steven C. Pennings, Jonathan Sanderman, Meagan Eagle, Christopher Craft, and Amanda C. Spivak
EGUsphere, https://doi.org/10.5194/egusphere-2024-1328, https://doi.org/10.5194/egusphere-2024-1328, 2024
Short summary
Short summary
Organic matter decay in salt marsh soils is not well understood. We used the Tea Bag Index, a standardized litter approach, to test how decay changes with soil depth, elevation, and time. The index overestimated decay but one component, rooibos tea, produced comparable rates to natural litter. We found that decay was higher at shallower depths and lower marsh elevations, suggesting that hydrologic setting may be a particularly important control on organic matter loss.
Patrick J. Neale, J. Patrick Megonigal, Maria Tzortziou, Elizabeth A. Canuel, Christina R. Pondell, and Hannah Morrissette
Biogeosciences, 21, 2599–2620, https://doi.org/10.5194/bg-21-2599-2024, https://doi.org/10.5194/bg-21-2599-2024, 2024
Short summary
Short summary
Adsorption/desorption incubations were conducted with tidal marsh soils to understand the differential sorption behavior of colored vs. noncolored dissolved organic carbon. The wetland soils varied in organic content, and a range of salinities of fresh to 35 was used. Soils primarily adsorbed colored organic carbon and desorbed noncolored organic carbon. Sorption capacity increased with salinity, implying that salinity variations may shift composition of dissolved carbon in tidal marsh waters.
Alexandra L. Hedgpeth, Alison M. Hoyt, Kyle Cavanaugh, Karis J. McFarlane, and Daniela F. Cusack
EGUsphere, https://doi.org/10.5194/egusphere-2024-1279, https://doi.org/10.5194/egusphere-2024-1279, 2024
Short summary
Short summary
Tropical peatlands store ancient carbon and have been identified as not only vulnerable to future climate change but take a long time to recover after disturbance. It is unknown if these gases are produced from decomposition of thousand-year-old peat. Radiocarbon dating shows emitted gases are young, indicating surface carbon, not old peat, drives emissions. Preserving these ecosystems can trap old carbon, mitigating climate change.
Leeza Speranskaya, David I. Campbell, Peter M. Lafleur, and Elyn R. Humphreys
Biogeosciences, 21, 1173–1190, https://doi.org/10.5194/bg-21-1173-2024, https://doi.org/10.5194/bg-21-1173-2024, 2024
Short summary
Short summary
Higher evaporation has been predicted in peatlands due to climatic drying. We determined whether the water-conservative vegetation at a Southern Hemisphere bog could cause a different response to dryness compared to a "typical" Northern Hemisphere bog, using decades-long evaporation datasets from each site. At the southern bog, evaporation increased at a much lower rate with increasing dryness, suggesting that this peatland type may be more resilient to climate warming than northern bogs.
James Stegen, Amy Burgin, Michelle Busch, Joshua Fisher, Joshua Ladau, Jenna Abrahamson, Lauren Kinsman-Costello, Li Li, Xingyuan Chen, Thibault Datry, Nate McDowell, Corianne Tatariw, Anna Braswell, Jillian Deines, Julia Guimond, Peter Regier, Kenton Rod, Edward Bam, Etienne Fluet-Chouinard, Inke Forbrich, Kristin Jaeger, Teri O'Meara, Tim Scheibe, Erin Seybold, Jon Sweetman, Jianqiu Zheng, Daniel Allen, Elizabeth Herndon, Beth Middleton, Scott Painter, Kevin Roche, Julianne Scamardo, Ross Vander Vorste, Kristin Boye, Ellen Wohl, Margaret Zimmer, Kelly Hondula, Maggi Laan, Anna Marshall, and Kaizad Patel
EGUsphere, https://doi.org/10.5194/egusphere-2024-98, https://doi.org/10.5194/egusphere-2024-98, 2024
Short summary
Short summary
The loss and gain of surface water (variable inundation) is a common process across Earth. Global change shifts variable inundation dynamics, highlighting a need for unified understanding that transcends individual variably inundated ecosystems (VIEs). We review literature, highlight challenges, and emphasize opportunities to generate transferable knowledge by viewing VIEs through a common lens. We aim to inspire the emergence of a cross-VIE community based on a proposed continuum approach.
Emilia Chiapponi, Sonia Silvestri, Denis Zannoni, Marco Antonellini, and Beatrice M. S. Giambastiani
Biogeosciences, 21, 73–91, https://doi.org/10.5194/bg-21-73-2024, https://doi.org/10.5194/bg-21-73-2024, 2024
Short summary
Short summary
Coastal wetlands are important for their ability to store carbon, but they also emit methane, a potent greenhouse gas. This study conducted in four wetlands in Ravenna, Italy, aims at understanding how environmental factors affect greenhouse gas emissions. Temperature and irradiance increased emissions from water and soil, while water column depth and salinity limited them. Understanding environmental factors is crucial for mitigating climate change in wetland ecosystems.
Jyrki Jauhiainen, Juha Heikkinen, Nicholas Clarke, Hongxing He, Lise Dalsgaard, Kari Minkkinen, Paavo Ojanen, Lars Vesterdal, Jukka Alm, Aldis Butlers, Ingeborg Callesen, Sabine Jordan, Annalea Lohila, Ülo Mander, Hlynur Óskarsson, Bjarni D. Sigurdsson, Gunnhild Søgaard, Kaido Soosaar, Åsa Kasimir, Brynhildur Bjarnadottir, Andis Lazdins, and Raija Laiho
Biogeosciences, 20, 4819–4839, https://doi.org/10.5194/bg-20-4819-2023, https://doi.org/10.5194/bg-20-4819-2023, 2023
Short summary
Short summary
The study looked at published data on drained organic forest soils in boreal and temperate zones to revisit current Tier 1 default emission factors (EFs) provided by the IPCC Wetlands Supplement. We examined the possibilities of forming more site-type specific EFs and inspected the potential relevance of environmental variables for predicting annual soil greenhouse gas balances by statistical models. The results have important implications for EF revisions and national emission reporting.
Jennifer Williamson, Chris Evans, Bryan Spears, Amy Pickard, Pippa J. Chapman, Heidrun Feuchtmayr, Fraser Leith, Susan Waldron, and Don Monteith
Biogeosciences, 20, 3751–3766, https://doi.org/10.5194/bg-20-3751-2023, https://doi.org/10.5194/bg-20-3751-2023, 2023
Short summary
Short summary
Managing drinking water catchments to minimise water colour could reduce costs for water companies and save their customers money. Brown-coloured water comes from peat soils, primarily around upland reservoirs. Management practices, including blocking drains, removing conifers, restoring peatland plants and reducing burning, have been used to try and reduce water colour. This work brings together published evidence of the effectiveness of these practices to aid water industry decision-making.
Ting Sun and Brian A. Branfireun
Biogeosciences, 20, 2971–2984, https://doi.org/10.5194/bg-20-2971-2023, https://doi.org/10.5194/bg-20-2971-2023, 2023
Short summary
Short summary
Shrub leaves had higher mercury concentrations than sedge leaves in the sedge-dominated peatland. Dead shrub leaves leached less soluble mercury but more bioaccessible dissolved organic matter than dead sedge leaves. Leached mercury was positively related to the aromaticity of dissolved organic matter in leachate. Future plant species composition changes under climate change will affect Hg input from plant leaves to northern peatlands.
Hao Tang, Stefanie Nolte, Kai Jensen, Roy Rich, Julian Mittmann-Goetsch, and Peter Mueller
Biogeosciences, 20, 1925–1935, https://doi.org/10.5194/bg-20-1925-2023, https://doi.org/10.5194/bg-20-1925-2023, 2023
Short summary
Short summary
In order to gain the first mechanistic insight into warming effects and litter breakdown dynamics across whole-soil profiles, we used a unique field warming experiment and standardized plant litter to investigate the degree to which rising soil temperatures can accelerate belowground litter breakdown in coastal wetland ecosystems. We found warming strongly increases the initial rate of labile litter decomposition but has less consistent effects on the stabilization of this material.
Raghab Ray, Rempei Suwa, Toshihiro Miyajima, Jeffrey Munar, Masaya Yoshikai, Maria Lourdes San Diego-McGlone, and Kazuo Nadaoka
Biogeosciences, 20, 911–928, https://doi.org/10.5194/bg-20-911-2023, https://doi.org/10.5194/bg-20-911-2023, 2023
Short summary
Short summary
Mangroves are blue carbon ecosystems known to store large amounts of organic carbon in the sediments. This study is a first attempt to apply a chronosequence (or space-for-time substitution) approach to evaluate the distribution and accumulation rate of carbon in a 30-year-old (maximum age) restored mangrove forest. Using this approach, the contribution of restored or planted mangroves to sedimentary organic carbon presents an increasing pattern with mangrove age.
Laura Clark, Ian B. Strachan, Maria Strack, Nigel T. Roulet, Klaus-Holger Knorr, and Henning Teickner
Biogeosciences, 20, 737–751, https://doi.org/10.5194/bg-20-737-2023, https://doi.org/10.5194/bg-20-737-2023, 2023
Short summary
Short summary
We determine the effect that duration of extraction has on CO2 and CH4 emissions from an actively extracted peatland. Peat fields had high net C emissions in the first years after opening, and these then declined to half the initial value for several decades. Findings contribute to knowledge on the atmospheric burden that results from these activities and are of use to industry in their life cycle reporting and government agencies responsible for greenhouse gas accounting and policy.
Daniel L. Pönisch, Anne Breznikar, Cordula N. Gutekunst, Gerald Jurasinski, Maren Voss, and Gregor Rehder
Biogeosciences, 20, 295–323, https://doi.org/10.5194/bg-20-295-2023, https://doi.org/10.5194/bg-20-295-2023, 2023
Short summary
Short summary
Peatland rewetting is known to reduce dissolved nutrients and greenhouse gases; however, short-term nutrient leaching and high CH4 emissions shortly after rewetting are likely to occur. We investigated the rewetting of a coastal peatland with brackish water and its effects on nutrient release and greenhouse gas fluxes. Nutrient concentrations were higher in the peatland than in the adjacent bay, leading to an export. CH4 emissions did not increase, which is in contrast to freshwater rewetting.
Stephen G. Chastain, Karen E. Kohfeld, Marlow G. Pellatt, Carolina Olid, and Maija Gailis
Biogeosciences, 19, 5751–5777, https://doi.org/10.5194/bg-19-5751-2022, https://doi.org/10.5194/bg-19-5751-2022, 2022
Short summary
Short summary
Salt marshes are thought to be important carbon sinks because of their ability to store carbon in their soils. We provide the first estimates of how much blue carbon is stored in salt marshes on the Pacific coast of Canada. We find that the carbon stored in the marshes is low compared to other marshes around the world, likely because of their young age. Still, the high marshes take up carbon at rates faster than the global average, making them potentially important carbon sinks in the future.
Jim Boonman, Mariet M. Hefting, Corine J. A. van Huissteden, Merit van den Berg, Jacobus (Ko) van Huissteden, Gilles Erkens, Roel Melman, and Ype van der Velde
Biogeosciences, 19, 5707–5727, https://doi.org/10.5194/bg-19-5707-2022, https://doi.org/10.5194/bg-19-5707-2022, 2022
Short summary
Short summary
Draining peat causes high CO2 emissions, and rewetting could potentially help solve this problem. In the dry year 2020 we measured that subsurface irrigation reduced CO2 emissions by 28 % and 83 % on two research sites. We modelled a peat parcel and found that the reduction depends on seepage and weather conditions and increases when using pressurized irrigation or maintaining high ditchwater levels. We found that soil temperature and moisture are suitable as indicators of peat CO2 emissions.
Maiju Linkosalmi, Juha-Pekka Tuovinen, Olli Nevalainen, Mikko Peltoniemi, Cemal M. Taniş, Ali N. Arslan, Juuso Rainne, Annalea Lohila, Tuomas Laurila, and Mika Aurela
Biogeosciences, 19, 4747–4765, https://doi.org/10.5194/bg-19-4747-2022, https://doi.org/10.5194/bg-19-4747-2022, 2022
Short summary
Short summary
Vegetation greenness was monitored with digital cameras in three northern peatlands during five growing seasons. The greenness index derived from the images was highest at the most nutrient-rich site. Greenness indicated the main phases of phenology and correlated with CO2 uptake, though this was mainly related to the common seasonal cycle. The cameras and Sentinel-2 satellite showed consistent results, but more frequent satellite data are needed for reliable detection of phenological phases.
Antonin Prijac, Laure Gandois, Laurent Jeanneau, Pierre Taillardat, and Michelle Garneau
Biogeosciences, 19, 4571–4588, https://doi.org/10.5194/bg-19-4571-2022, https://doi.org/10.5194/bg-19-4571-2022, 2022
Short summary
Short summary
Pools are common features of peatlands. We documented dissolved organic matter (DOM) composition in pools and peat of an ombrotrophic boreal peatland to understand its origin and potential role in the peatland carbon budget. The survey reveals that DOM composition differs between pools and peat, although it is derived from the peat vegetation. We investigated which processes are involved and estimated that the contribution of carbon emissions from DOM processing in pools could be substantial.
Cordula Nina Gutekunst, Susanne Liebner, Anna-Kathrina Jenner, Klaus-Holger Knorr, Viktoria Unger, Franziska Koebsch, Erwin Don Racasa, Sizhong Yang, Michael Ernst Böttcher, Manon Janssen, Jens Kallmeyer, Denise Otto, Iris Schmiedinger, Lucas Winski, and Gerald Jurasinski
Biogeosciences, 19, 3625–3648, https://doi.org/10.5194/bg-19-3625-2022, https://doi.org/10.5194/bg-19-3625-2022, 2022
Short summary
Short summary
Methane emissions decreased after a seawater inflow and a preceding drought in freshwater rewetted coastal peatland. However, our microbial and greenhouse gas measurements did not indicate that methane consumers increased. Rather, methane producers co-existed in high numbers with their usual competitors, the sulfate-cycling bacteria. We studied the peat soil and aimed to cover the soil–atmosphere continuum to better understand the sources of methane production and consumption.
Liam Heffernan, Maria A. Cavaco, Maya P. Bhatia, Cristian Estop-Aragonés, Klaus-Holger Knorr, and David Olefeldt
Biogeosciences, 19, 3051–3071, https://doi.org/10.5194/bg-19-3051-2022, https://doi.org/10.5194/bg-19-3051-2022, 2022
Short summary
Short summary
Permafrost thaw in peatlands leads to waterlogged conditions, a favourable environment for microbes producing methane (CH4) and high CH4 emissions. High CH4 emissions in the initial decades following thaw are due to a vegetation community that produces suitable organic matter to fuel CH4-producing microbes, along with warm and wet conditions. High CH4 emissions after thaw persist for up to 100 years, after which environmental conditions are less favourable for microbes and high CH4 emissions.
Julia Gensel, Marc Steven Humphries, Matthias Zabel, David Sebag, Annette Hahn, and Enno Schefuß
Biogeosciences, 19, 2881–2902, https://doi.org/10.5194/bg-19-2881-2022, https://doi.org/10.5194/bg-19-2881-2022, 2022
Short summary
Short summary
We investigated organic matter (OM) and plant-wax-derived biomarkers in sediments and plants along the Mkhuze River to constrain OM's origin and transport pathways within South Africa's largest freshwater wetland. Presently, it efficiently captures OM, so neither transport from upstream areas nor export from the swamp occurs. Thus, we emphasize that such geomorphological features can alter OM provenance, questioning the assumption of watershed-integrated information in downstream sediments.
Petri Kiuru, Marjo Palviainen, Tiia Grönholm, Maarit Raivonen, Lukas Kohl, Vincent Gauci, Iñaki Urzainki, and Annamari Laurén
Biogeosciences, 19, 1959–1977, https://doi.org/10.5194/bg-19-1959-2022, https://doi.org/10.5194/bg-19-1959-2022, 2022
Short summary
Short summary
Peatlands are large sources of methane (CH4), and peat structure controls CH4 production and emissions. We used X-ray microtomography imaging, complex network theory methods, and pore network modeling to describe the properties of peat macropore networks and the role of macropores in CH4-related processes. We show that conditions for gas transport and CH4 production vary with depth and are affected by hysteresis, which may explain the hotspots and episodic spikes in peatland CH4 emissions.
Rey Harvey Suello, Simon Lucas Hernandez, Steven Bouillon, Jean-Philippe Belliard, Luis Dominguez-Granda, Marijn Van de Broek, Andrea Mishell Rosado Moncayo, John Ramos Veliz, Karem Pollette Ramirez, Gerard Govers, and Stijn Temmerman
Biogeosciences, 19, 1571–1585, https://doi.org/10.5194/bg-19-1571-2022, https://doi.org/10.5194/bg-19-1571-2022, 2022
Short summary
Short summary
This research shows indications that the age of the mangrove forest and its position along a deltaic gradient (upstream–downstream) play a vital role in the amount and sources of carbon stored in the mangrove sediments. Our findings also imply that carbon capture by the mangrove ecosystem itself contributes partly but relatively little to long-term sediment organic carbon storage. This finding is particularly relevant for budgeting the potential of mangrove ecosystems to mitigate climate change.
Hao Tang, Susanne Liebner, Svenja Reents, Stefanie Nolte, Kai Jensen, Fabian Horn, and Peter Mueller
Biogeosciences, 18, 6133–6146, https://doi.org/10.5194/bg-18-6133-2021, https://doi.org/10.5194/bg-18-6133-2021, 2021
Short summary
Short summary
We examined if sea-level rise and plant genotype interact to affect soil microbial functioning in a mesocosm experiment using two genotypes of a dominant salt-marsh grass characterized by differences in flooding sensitivity. Larger variability in microbial community structure, enzyme activity, and litter breakdown in soils with the more sensitive genotype supports our hypothesis that effects of climate change on soil microbial functioning can be controlled by plant intraspecific adaptations.
Naima Iram, Emad Kavehei, Damien T. Maher, Stuart E. Bunn, Mehran Rezaei Rashti, Bahareh Shahrabi Farahani, and Maria Fernanda Adame
Biogeosciences, 18, 5085–5096, https://doi.org/10.5194/bg-18-5085-2021, https://doi.org/10.5194/bg-18-5085-2021, 2021
Short summary
Short summary
Greenhouse gas emissions were measured and compared from natural coastal wetlands and their converted agricultural lands across annual seasonal cycles in tropical Australia. Ponded pastures emitted ~ 200-fold-higher methane than any other tested land use type, suggesting the highest greenhouse gas mitigation potential and financial incentives by the restoration of ponded pastures to natural coastal wetlands.
Pavel Alekseychik, Aino Korrensalo, Ivan Mammarella, Samuli Launiainen, Eeva-Stiina Tuittila, Ilkka Korpela, and Timo Vesala
Biogeosciences, 18, 4681–4704, https://doi.org/10.5194/bg-18-4681-2021, https://doi.org/10.5194/bg-18-4681-2021, 2021
Short summary
Short summary
Bogs of northern Eurasia represent a major type of peatland ecosystem and contain vast amounts of carbon, but carbon balance monitoring studies on bogs are scarce. The current project explores 6 years of carbon balance data obtained using the state-of-the-art eddy-covariance technique at a Finnish bog Siikaneva. The results reveal relatively low interannual variability indicative of ecosystem resilience to both cool and hot summers and provide new insights into the seasonal course of C fluxes.
Timea Katona, Benjamin Silas Gilfedder, Sven Frei, Matthias Bücker, and Adrian Flores-Orozco
Biogeosciences, 18, 4039–4058, https://doi.org/10.5194/bg-18-4039-2021, https://doi.org/10.5194/bg-18-4039-2021, 2021
Short summary
Short summary
We used electrical geophysical methods to map variations in the rates of microbial activity within a wetland. Our results show that the highest electrical conductive and capacitive properties relate to the highest concentrations of phosphates, carbon, and iron; thus, we can use them to characterize the geometry of the biogeochemically active areas or hotspots.
Jurek Müller and Fortunat Joos
Biogeosciences, 18, 3657–3687, https://doi.org/10.5194/bg-18-3657-2021, https://doi.org/10.5194/bg-18-3657-2021, 2021
Short summary
Short summary
We present long-term projections of global peatland area and carbon with a continuous transient history since the Last Glacial Maximum. Our novel results show that large parts of today’s northern peatlands are at risk from past and future climate change, with larger emissions clearly connected to larger risks. The study includes comparisons between different emission and land-use scenarios, driver attribution through factorial simulations, and assessments of uncertainty from climate forcing.
Lianlian Zhu, Zhengmiao Deng, Yonghong Xie, Xu Li, Feng Li, Xinsheng Chen, Yeai Zou, Chengyi Zhang, and Wei Wang
Biogeosciences, 18, 1–11, https://doi.org/10.5194/bg-18-1-2021, https://doi.org/10.5194/bg-18-1-2021, 2021
Short summary
Short summary
We conducted a Carex brevicuspis leaf litter input experiment to clarify the intrinsic factors controlling litter decomposition and quantify its contribution to the soil organic carbon pool at different water levels. Our results revealed that the water level in natural wetlands influenced litter decomposition mainly by leaching and microbial activity, by extension, and affected the wetland surface carbon pool.
Robert J. Parker, Chris Wilson, A. Anthony Bloom, Edward Comyn-Platt, Garry Hayman, Joe McNorton, Hartmut Boesch, and Martyn P. Chipperfield
Biogeosciences, 17, 5669–5691, https://doi.org/10.5194/bg-17-5669-2020, https://doi.org/10.5194/bg-17-5669-2020, 2020
Short summary
Short summary
Wetlands contribute the largest uncertainty to the atmospheric methane budget. WetCHARTs is a simple, data-driven model that estimates wetland emissions using observations of precipitation and temperature. We perform the first detailed evaluation of WetCHARTs against satellite data and find it performs well in reproducing the observed wetland methane seasonal cycle for the majority of wetland regions. In regions where it performs poorly, we highlight incorrect wetland extent as a key reason.
Jurek Müller and Fortunat Joos
Biogeosciences, 17, 5285–5308, https://doi.org/10.5194/bg-17-5285-2020, https://doi.org/10.5194/bg-17-5285-2020, 2020
Short summary
Short summary
We present an in-depth model analysis of transient peatland area and carbon dynamics over the last 22 000 years. Our novel results show that the consideration of both gross positive and negative area changes are necessary to understand the transient evolution of peatlands and their net effect on atmospheric carbon. The study includes the attributions to drivers through factorial simulations, assessments of uncertainty from climate forcing, and determination of the global net carbon balance.
Lilli Zeh, Marie Theresa Igel, Judith Schellekens, Juul Limpens, Luca Bragazza, and Karsten Kalbitz
Biogeosciences, 17, 4797–4813, https://doi.org/10.5194/bg-17-4797-2020, https://doi.org/10.5194/bg-17-4797-2020, 2020
Jérémy Guilhen, Ahmad Al Bitar, Sabine Sauvage, Marie Parrens, Jean-Michel Martinez, Gwenael Abril, Patricia Moreira-Turcq, and José-Miguel Sánchez-Pérez
Biogeosciences, 17, 4297–4311, https://doi.org/10.5194/bg-17-4297-2020, https://doi.org/10.5194/bg-17-4297-2020, 2020
Short summary
Short summary
The quantity of greenhouse gases (GHGs) released to the atmosphere by human industries and agriculture, such as carbon dioxide (CO2) and nitrous oxide (N2O), has been constantly increasing for the last few decades.
This work develops a methodology which makes consistent both satellite observations and modelling of the Amazon basin to identify and quantify the role of wetlands in GHG emissions. We showed that these areas produce non-negligible emissions and are linked to land use.
Thomas Rosset, Stéphane Binet, Jean-Marc Antoine, Emilie Lerigoleur, François Rigal, and Laure Gandois
Biogeosciences, 17, 3705–3722, https://doi.org/10.5194/bg-17-3705-2020, https://doi.org/10.5194/bg-17-3705-2020, 2020
Short summary
Short summary
Peatlands export a large amount of DOC through inland waters. This study aims at identifying the mechanisms controlling the DOC concentration at the outlet of two mountainous peatlands in the French Pyrenees. Peat water temperature and water table dynamics are shown to drive seasonal- and event-scale DOC concentration variation. According to water recession times, peatlands appear as complexes of different hydrological and biogeochemical units supplying inland waters at different rates.
David Holl, Eva-Maria Pfeiffer, and Lars Kutzbach
Biogeosciences, 17, 2853–2874, https://doi.org/10.5194/bg-17-2853-2020, https://doi.org/10.5194/bg-17-2853-2020, 2020
Short summary
Short summary
We measured greenhouse gas (GHG) fluxes at a bog site in northwestern Germany that has been heavily degraded by peat mining. During the 2-year investigation period, half of the area was still being mined, whereas the remaining half had been rewetted shortly before. We could therefore estimate the impact of rewetting on GHG flux dynamics. Rewetting had a considerable effect on the annual GHG balance and led to increased (up to 84 %) methane and decreased (up to 40 %) carbon dioxide release.
Jacob S. Diamond, Daniel L. McLaughlin, Robert A. Slesak, and Atticus Stovall
Biogeosciences, 17, 901–915, https://doi.org/10.5194/bg-17-901-2020, https://doi.org/10.5194/bg-17-901-2020, 2020
Short summary
Short summary
Many wetland systems exhibit lumpy, or uneven, soil surfaces where higher points are called hummocks and lower points are called hollows. We found that, while hummocks extended only ~ 20 cm above hollow surfaces, they exhibited distinct plant communities, plant growth, and soil properties. Differences between hummocks and hollows were the greatest in wetter sites, supporting the hypothesis that plants create and maintain their own hummocks in response to saturated soil conditions.
Terhi Riutta, Aino Korrensalo, Anna M. Laine, Jukka Laine, and Eeva-Stiina Tuittila
Biogeosciences, 17, 727–740, https://doi.org/10.5194/bg-17-727-2020, https://doi.org/10.5194/bg-17-727-2020, 2020
Short summary
Short summary
We studied the role of plant species groups in peatland methane fluxes under natural conditions and lowered water level. At a natural water level, sedges and mosses increased the fluxes. At a lower water level, the impact of plant groups on the fluxes was small. Only at a high water level did vegetation regulate the fluxes. The results are relevant for assessing peatland methane fluxes in a changing climate, as peatland water level and vegetation are predicted to change.
M. Graham Clark, Elyn R. Humphreys, and Sean K. Carey
Biogeosciences, 17, 667–682, https://doi.org/10.5194/bg-17-667-2020, https://doi.org/10.5194/bg-17-667-2020, 2020
Short summary
Short summary
Natural and restored wetlands typically emit methane to the atmosphere. However, we found that a wetland constructed after oil sand mining in boreal Canada using organic soils from local peatlands had negligible emissions of methane in its first 3 years. Methane production was likely suppressed due to an abundance of alternate inorganic electron acceptors. Methane emissions may increase in the future if the alternate electron acceptors continue to decrease.
Hendrik Reuter, Julia Gensel, Marcus Elvert, and Dominik Zak
Biogeosciences, 17, 499–514, https://doi.org/10.5194/bg-17-499-2020, https://doi.org/10.5194/bg-17-499-2020, 2020
Short summary
Short summary
Using infrared spectroscopy, we developed a routine to disentangle microbial nitrogen (N) and plant N in decomposed litter. In a decomposition experiment in three wetland soils, this routine revealed preferential protein depolymerization as a decomposition-site-dependent parameter, unaffected by variations in initial litter N content. In Sphagnum peat, preferential protein depolymerization led to a N depletion of still-unprocessed litter tissue, i.e., a gradual loss of litter quality.
Kevan J. Minick, Bhaskar Mitra, Asko Noormets, and John S. King
Biogeosciences, 16, 4671–4686, https://doi.org/10.5194/bg-16-4671-2019, https://doi.org/10.5194/bg-16-4671-2019, 2019
Short summary
Short summary
Sea level rise alters hydrology and vegetation in coastal wetlands. We studied effects of freshwater, saltwater, and wood on soil microbial activity in a freshwater forested wetland. Saltwater reduced CO2/CH4 production compared to freshwater, suggesting large changes in greenhouse gas production and microbial activity are possible due to saltwater intrusion into freshwater wetlands but that the availability of C in the form of dead wood (as forests transition to marsh) may alter the magnitude.
Jyrki Jauhiainen, Jukka Alm, Brynhildur Bjarnadottir, Ingeborg Callesen, Jesper R. Christiansen, Nicholas Clarke, Lise Dalsgaard, Hongxing He, Sabine Jordan, Vaiva Kazanavičiūtė, Leif Klemedtsson, Ari Lauren, Andis Lazdins, Aleksi Lehtonen, Annalea Lohila, Ainars Lupikis, Ülo Mander, Kari Minkkinen, Åsa Kasimir, Mats Olsson, Paavo Ojanen, Hlynur Óskarsson, Bjarni D. Sigurdsson, Gunnhild Søgaard, Kaido Soosaar, Lars Vesterdal, and Raija Laiho
Biogeosciences, 16, 4687–4703, https://doi.org/10.5194/bg-16-4687-2019, https://doi.org/10.5194/bg-16-4687-2019, 2019
Short summary
Short summary
We collated peer-reviewed publications presenting GHG flux data for drained organic forest soils in boreal and temperate climate zones, focusing on data that have been used, or have the potential to be used, for estimating net annual soil GHG emission/removals. We evaluated the methods in data collection and identified major gaps in background/environmental data. Based on these, we developed suggestions for future GHG data collection to increase data applicability in syntheses and inventories.
Steffen Buessecker, Kaitlyn Tylor, Joshua Nye, Keith E. Holbert, Jose D. Urquiza Muñoz, Jennifer B. Glass, Hilairy E. Hartnett, and Hinsby Cadillo-Quiroz
Biogeosciences, 16, 4601–4612, https://doi.org/10.5194/bg-16-4601-2019, https://doi.org/10.5194/bg-16-4601-2019, 2019
Short summary
Short summary
We investigated the potential for chemical reduction of nitrite into nitrous oxide (N2O) in soils from tropical peat. Among treatments, irradiation resulted in the lowest biological interference and least change of native soil chemistry (iron and organic matter). Nitrite depletion was as high in live or irradiated soils, and N2O production was significant in all tests. Thus, nonbiological production of N2O may be widely underestimated in wetlands and tropical peatlands.
Ward Swinnen, Nils Broothaerts, and Gert Verstraeten
Biogeosciences, 16, 3977–3996, https://doi.org/10.5194/bg-16-3977-2019, https://doi.org/10.5194/bg-16-3977-2019, 2019
Short summary
Short summary
In this study, a new model is presented, which was specifically designed to study the development and carbon storage of blanket peatlands since the last ice age. In the past, two main processes (declining forest cover and rising temperatures) have been proposed as drivers of blanket peatland development on the British Isles. The simulations performed in this study support the temperature hypothesis for the blanket peatlands in the Cairngorms Mountains of central Scotland.
David Holl, Verónica Pancotto, Adrian Heger, Sergio Jose Camargo, and Lars Kutzbach
Biogeosciences, 16, 3397–3423, https://doi.org/10.5194/bg-16-3397-2019, https://doi.org/10.5194/bg-16-3397-2019, 2019
Short summary
Short summary
We present 2 years of eddy covariance carbon dioxide flux data from two Southern Hemisphere peatlands on Tierra del Fuego. One of the investigated sites is a type of bog exclusive to the Southern Hemisphere, which is dominated by vascular, cushion-forming plants and is particularly understudied. One result of this study is that these cushion bogs apparently are highly productive in comparison to Northern and Southern Hemisphere moss-dominated bogs.
Liudmila S. Shirokova, Artem V. Chupakov, Svetlana A. Zabelina, Natalia V. Neverova, Dahedrey Payandi-Rolland, Carole Causserand, Jan Karlsson, and Oleg S. Pokrovsky
Biogeosciences, 16, 2511–2526, https://doi.org/10.5194/bg-16-2511-2019, https://doi.org/10.5194/bg-16-2511-2019, 2019
Short summary
Short summary
Regardless of the size and landscape context of surface water in frozen peatland in NE Europe, the bio- and photo-degradability of dissolved organic matter (DOM) over a 1-month incubation across a range of temperatures was below 10 %. We challenge the paradigm of dominance of photolysis and biodegradation in DOM processing in surface waters from frozen peatland, and we hypothesize peat pore-water DOM degradation and respiration of sediments to be the main drivers of CO2 emission in this region.
Elisa Männistö, Aino Korrensalo, Pavel Alekseychik, Ivan Mammarella, Olli Peltola, Timo Vesala, and Eeva-Stiina Tuittila
Biogeosciences, 16, 2409–2421, https://doi.org/10.5194/bg-16-2409-2019, https://doi.org/10.5194/bg-16-2409-2019, 2019
Short summary
Short summary
We studied methane emitted as episodic bubble release (ebullition) from water and bare peat surfaces of a boreal bog over three years. There was more ebullition from water than from bare peat surfaces, and it was controlled by peat temperature, water level, atmospheric pressure and the weekly temperature sum. However, the contribution of methane bubbles to the total ecosystem methane emission was small. This new information can be used to improve process models of peatland methane dynamics.
Cited articles
Ågren, G. I., Bosatta, E., and Balesdent, J.: Isotope discrimination during decomposition of organic matter: A theoretical analysis, Soil Sci. Soc. Am. J., 60, 1121–1126, 1996.
Åkerman, J. H. and Johansson, M.: Thawing Permafrost and Thicker Active Layers in Sub-arctic Sweden, Permafr. Perigl. Proc., 19, 279–292, 2008.
Alewell, C., Giesler, R., Klaminder, J., Leifeld, J., and Rollog, M.: Stable carbon isotopes as indicators for environmental change in palsa peats, Biogeosciences, 8, 1769–1778, https://doi.org/10.5194/bg-8-1769-2011, 2011.
Andersson, R. A., Meyers, P., Hornibrook, E., Kuhry, P., and Mörth, C.-M.: Elemental and isotopic carbon and nitrogen records of organic matter accumulation in a Holocene permafrost peat sequence in the East European Russian Arctic, J. Quat. Sci., 27, 545–552, 2012.
Bäckstrand, K., Crill, P. M., Jackowicz-Korczyñski, M., Mastepanov, M., Christensen, T. R., and Bastviken, D.: Annual carbon gas budget for a subarctic peatland, Northern Sweden, Biogeosciences, 7, 95–108, https://doi.org/10.5194/bg-7-95-2010, 2010.
Benner, R., Fogel, M. L., Spargue, E. K., and Hodson, R. E.: Depletion of C-13 in Lignin and Its Implications for Stable Carbon Isotope Studies, Nature, 329, 708–710, 1987.
Bosiö, J., Johansson, M., Callaghan, T.V., Johansen, B., and Christensen, T.R.: Future vegetation changes in thawing subarctic mires and implications for greenhouse gas exchange – a regional assessment, Clim. Change 115, 379–398, 2012.
Broder, T., Blodau, C., Biester, H., and Knorr, K. H.: Peat decomposition records in three pristine ombrotrophic bogs in southern Patagonia, Biogeosciences, 9, 1479–1491, https://doi.org/10.5194/bg-9-1479-2012, 2012.
Christensen, T. R., Johansson, T., Åkerman, H. J., Mastepanov, M., Malmer, N., Friborg, T., Crill, P., and Svensson, B. H.: Thawing sub-arctic permafrost: Effects on vegetation and methane emissions, Geophys. Res. Lett., 31, L04501, https://doi.org/10.1029/2003GL018680, 2004.
Clymo, R. S. and Bryant, C. L.: Di?usion and mass ?ow of dissolved carbon dioxide, methane, and dissolved organic carbon in a 7-m deep raised peat bog, Geochimica et Cosmochimica Acta, 72, 2048–2066, 2008.
de Jong, R., Blaauw, M., Chambers, F. M., Christensen, T. R., de Vleeschouwer, F., Finsinger, W., Fronzek, S., Johansson, M., Kokfelt, U., Lamentowicz, M., LeRoux, G., Mauquoy, D., Mitchell, E. A. D., Nichols, J.E., Samaritani, E., and van Gell, B.: Climate and Peatlands, edited by: Dodson, J., Changing Climates, Earth Systems, and Society, Springer, Heidelberg, 85–121, 2010.
Dorrepaal, E., Toet, S., van Logtestijn, R. S. P., Swart, E., van de Weg, M. J., Callaghan, T. V., and Aerts, R.: Carbon respiration from subsurface peat accelerated by climate warming in the subarctic, Nature, 460, 616–619, 2009.
Esmeijer-Liu, A. J., Kürschner, W. M., Lotter, A. F., Verhoeven, J. T. A., and Goslar, T.: Stable Carbon and Nitrogen Isotopes in a Peat Profile Are Influenced by Early Stage Diagenesis and Changes in Atmospheric CO2 and N Deposition, Water Air Soil Pollut, 223, 2007–2022, 2012.
Fronzek, S., Luoto, M., and Carter, T. R.: Potential effect of climate change on the distribution of palsa mires in subarctic Fennoscandia, Clim. Res., 32, 1–12, 2006.
Fronzek, S., Carter, T. R., Räisän, J., Ruokolainen, L., and Luoto, M.: Applying probabilistic projections of climate change with impacts models: a case study for sub-arctic palsa mires in Fennoscandia, Clim. Change, 99, 515–534, 2010.
Gorham, E.: Northern Peatlands: Role in the Carbon Cycle and Probable Response to Climate Warming, Ecol. Appl., 1, 182–195, 1991.
Hornibrook, E. R. C., Longstaffe, F. J., Fyfe, W. S., and Bloom, Y.: Carbon-isotope ratios and carbon, nitrogen and sulfur abundance in flora and soil organic matter from a temperate-zone bog and march, Geochem. J., 34, 237–245, 2000.
Johansson, T., Malmer, N., Crill, P. M., Friborg, T., Åkerman, J. H., Mastepanov, M., and Christensen, T. R.: Decadel vegetation changes in a northern peatland, greenhouse gas fluxes and radiative forcing, Glob. Change Biol., 12, 2352–2369, 2006.
Jones, M. C., Peteet, D. M., and Sambrotto, R.: Late-glacial and Holocene δ15N and δ13C variation from a Kenai Peninsula, Alaska peatland, Paleogeogr. Paleoclimatol. Paleoecol., 293, 132–143, 2010.
Joosten, H. and Clarke, D.: The wise use of mires and peatlands - Background and principles including a framework for decision-making, in: International Mire Conservation Group and International Peat Society (eds.) NHTS Ltd, Devon, UK, available online at: http://www.imcg.net/docum/WUMP_Wise_Use_of_Mires_and_Peatlands_book.pdf, 2002.
Jungkunst, H. F., Krüger, J. P., Heitkamp, F., Erasmi, S., Fiedler, S., Glatzel, S., and Lal, R.: Accounting more precisely for peat and other soil carbon resources, in: Recarbonization of the biosphere – ecosystems and the global carbon cycle, edited by: Lal, R., Lorenz, K., Hüttl, R. F. J., Schneider, B. U., and von Braun, J., Springer, Amsterdam, 127–157, 2012.
Keuper, F., van Bodegom, P. M., Dorrepaal, E., Weedon, J. T., van Hal, J., van Logtestijn, R. S. P., and Aerts, R.: A frozen feast: thawing permafrost increases plant-available nitrogen in subarctic peatlands, Glob. Change Biol., 18, 1998–2007, 2012.
Klaminder, J., Yoo, K., Rydberg, J., and Giesler, R.: An explorative study of mercury export from a thawing palsa mire, J. Geophys. Res.-Biogeosci., 113, 1–9, 2008.
Kokfelt, U., Reuss, N., Struyf, E., Sonesson, M., Rundgren, M., Skog, G., Rosen, P., and Hammarlund, D.: Wetland development, permafrost history and nutrient cycling inferred from late Holocene peat and lake sediment records in subarctic Sweden, J. Paleolimnol., 44, 327–342, 2010.
Krull, E. S. and Retallack, G. J.: δ13C depth profiles from paleosols across the Permian-Triassic boundary: Evidence for methane release, Geol. Soc. Am. Bull., 112, 1459–1472, 2000.
Kuhry, P. and Vitt, D. H.: Fossil carbon/nitrogen ratios as a measure of peat decomposition, Ecology, 77, 271–275, 1996.
Lal, R.: Carbon sequestration, Philosophical transactions of the royal society B, Vol. 363, (August), 815–830, 2008.
Lemke, P., Ren, J., Alley, R. B., Allison, I., Carrasco, J., Flato, G., Fujii, Y., Kaser, G., Mote, P., Thomas, R. H., and Zhang, T.: Observations: Changes in Snow, Ice and Frozen Ground, in: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, eidted by: Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K. B., Tignor, M., and Miller, H. L., Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 337–384, 2007.
Lund, M., Christensen, T. R., Mastepanov, M., Lindroth, A., and Ström, L.: Effects of N and P fertilization on the greenhouse gas exchange in two northern peatlands with contrasting N deposition rates, Biogeosciences, 6, 2135–2144, https://doi.org/10.5194/bg-6-2135-2009, 2009.
Luoto, M. and Seppälä, M.: Modelling the Distribution of Palsas in Finnish Lapland with Logistic Regression and GIS, Permafrost Periglac. Process., 13, 17–28, 2002.
Luoto, M. and Seppälä, M.: Thermokarst Ponds as Indicators of the Former Distribution of Palsas in Finnish Lapland, Permafrost Periglac. Process., 14, 19–27, 2003.
Luoto, M., Heikkinen, R. K., and Carter, T. R.: Loss of palsa mires in Europe and biological consequences, Environ. Conserv., 31, 30–37, 2004.
Malmer, N. and Holm, E.: Variation of the C / N-Quotient of Peat in Relation to Decomposition Rate and Age Determination with 210 PB, Oikos, 43, 171–182, 1984.
Malmer, N. and Wallén, B.: Peat formation and mass balance in subarctic ombrotrophic peatlands around Abisko, northern Sweden, Ecol. Bullet., 45, 79–92, 1996.
Malmer, N., Johansson, T., Olsrud, M., and Christensen, T. R.: Vegetation, climate changes and net carbon sequestration in a North-Scandinavian subarctic mire over 30 years, Glob. Change Biol., 11, 1895–1909, 2005.
Marushchak, M. E., Pitkämäki, A., Koponen, H., Biasi, C., Seppälä, M., and Martikainen, P. J.: Hot spots for nitrous oxide emissions found in different types of permafrost peatlands, Glob. Change Biol., 17, 2601–2614, 2011.
Menot, G. and Burns, S. J.: Carbon isotopes in ombrogenic peat bog plants as climatic indicators: calibration from altitudinal transect in Switzerland, Org. Geochem., 32, 233–245, 2001.
Nadelhoffer, K. F. and Fry, B.: Controls on natural 15N and 13C abundance in forest soil organic matter, Soil Sci. Soc. Am. J., 52, 1633–1640, 1988.
Olefeldt, D. and Roulet, N. T.: Effects of permafrost and hydrology on the composition and transport of dissolved organic carbon in a subarctic peatland complex, J. Geophys. Res., 117, G01005, https://doi.org/10.1029/2011JG001819, 2012.
Olefeldt, D., Roulet, N. T., Bergeron, O., Crill, P., Bäckstrand, K., and Christensen, T. R.: Net carbon accumulation of a high-latitude permafrost palsa mire similar to permafrost-free peatlands, Geophys. Res. Lett., 39, L03501, https://doi.org/10.1029/2011GL050355, 2012.
Pengerud, A., Cécillon, L., Johnsen, L. K., Rasse, D. P., and Strand, L. T.: Permafrost Distribution Drives Soil Organic Matter Stability in a Subarctic Palsa Peatland, Ecosystems, 16, 934–947, 2013.
Price, G. D., McKenzie, J. E., Pilcher, J. R., and Hoper, S. T.: Carbon-isotope variation in Sphagnum form hummock-hollow complexes: Implication for Holocene climate reconstruction, Holocene, 7, 229–233, 1997.
Repo, M. E., Susiluoto, S., Lind, S. E., Jokinen, S., Elsakov, V., Biasi, C., Virtanen, T., and Martikainen, P. J.: Large N2O emissions from cryoturbated peat soils in tundra, Nat. Geosci., 2, 189–192, 2009.
Rydberg, J., Klaminder, J., Rosen, P., and Bindler, R.: Climate driven release of carbon and mercury from permafrost mires increases mercury loading to sub-arctic lakes, Sci. Total Environ., 408, 4778–4783, 2010.
Schaub, M. and Alewell, C.: Stable carbon isotopes as an indicator for soil degradation in an alpine environment (Urseren Valley, Switzerland), Rapid Commun. Mass Spectrom., 23, 1499–1507, 2009.
Schuur, E. A. G., Vogel, J. G., Crummer, K. G., Lee, H., Sickman, J. O., and Osterkamp, T. E.: The effect of permafrost thaw on old carbon release and net carbon exchange from tundra, Nature, 459, 556–559, 2009.
Seppälä, M.: Surface abrasion of palsas by wind action in Finnish Lapland, Geomorphology, 52, 141–148, 2003.
Seppälä, M.: Palsa mires in Finland, in: The Finnish Environment 23/2006, Lindholm, T. and Heikkilä, R., 155–162, 2006.
Tarnocai, C., Canadell, J. G., Schuur, E. A. G., Kuhry, P., Mazhitova, G., and Zimov, S.: Soil organic carbon pools in the northern circumpolar permafrost region, Global Biogeochem. Cy., 23, GB2023, https://doi.org/10.1029/2008GB003327, 2009.
Turetsky, M. R.: Decomposition and Organic Matter Quality in Continental Peatlands: The Ghost of Permafrost Past, Ecosystems, 7, 740–750, 2004.
Yu, Z., Beilman, D. W., Frolking, S., MacDonald, G. M., Roulet, N. T., Camill, P., and Charman, D. J.: Peatlands and Their Role in the Global Carbon Cycle, EOS, 92, 97–98, 2011.
Altmetrics
Final-revised paper
Preprint