A5015578533- Climate change and permafrost
- Peatlands and Wetlands Ecology
- Geology and Paleoclimatology Research
- Methane Hydrates and Related Phenomena
- Cryospheric studies and observations
- Coastal wetland ecosystem dynamics
- Soil and Unsaturated Flow
- Fire effects on ecosystems
- Atmospheric and Environmental Gas Dynamics
- Forest ecology and management
- Soil Geostatistics and Mapping
- Forest Ecology and Biodiversity Studies
- Landslides and related hazards
- Soil Carbon and Nitrogen Dynamics
- Image Processing and 3D Reconstruction
- Toxic Organic Pollutants Impact
- Wastewater Treatment and Nitrogen Removal
- Chemical Reactions and Isotopes
- Karst Systems and Hydrogeology
- Botany and Plant Ecology Studies
- Constructed Wetlands for Wastewater Treatment
- Water Treatment and Disinfection
- Arctic and Antarctic ice dynamics
- Microbial bioremediation and biosurfactants
- Geological Studies and Exploration
University of Münster
2013-2024
University of Alberta
2015-2022
University of Exeter
2014-2020
University of Bayreuth
2011-2016
Institute of Groundwater Ecology
2013
Helmholtz Centre for Environmental Research
2008-2009
Carbon release from thawing permafrost soils could significantly exacerbate global warming as the active-layer deepens, exposing more carbon to decay. Plant community and soil properties provide a major control on this by influencing maximum depth of thaw each summer (active-layer thickness; ALT), but quantitative understanding relative importance plant characteristics, their interactions in determine ALTs, is currently lacking. To address this, we undertook an extensive survey multiple...
Abstract. Radiocarbon is a critical constraint on our estimates of the timescales soil carbon cycling that can aid in identifying mechanisms stabilization and destabilization improve forecast response to management or environmental change. Despite wealth radiocarbon data have been reported over past 75 years, ability apply these global-scale questions limited by capacity synthesize compare measurements generated using variety methods. Here, we present International Soil Database (ISRaD;...
Abstract The magnitude of future emissions greenhouse gases from the northern permafrost region depends crucially on mineralization soil organic carbon (SOC) that has accumulated over millennia in these perennially frozen soils. Many recent studies have used radiocarbon ( 14 C) to quantify release this “old” SOC as CO 2 or CH 4 atmosphere dissolved and particulate (DOC POC) surface waters. We compiled ~1,900 C measurements 51 sites assess vulnerability thawing tundra, forest, peatland, lake,...
Permafrost peatlands store globally significant amounts of soil organic carbon (SOC) that may be vulnerable to climate change. thaw exposes deeper, older SOC microbial activity, but vulnerability mineralization and release as dioxide is likely influenced by the environmental conditions follow thaw. in peat plateaus, dominant type permafrost North America, occurs both through deepening active layer thermokarst. Active aged predominately oxic conditions, while thermokarst associated with...
Abstract Peatlands in northern permafrost regions store a significant proportion of global soil carbon. Recent warming is accelerating peatland thaw and thermokarst collapse, exposing previously frozen peat to microbial decomposition potential mineralization into greenhouse gases. Here, we show from site the sporadic‐discontinuous zone western Canada that collapse leads neither large losses nor gains following thaw, as deep carbon are offset by surficial accumulation. We collected cores...
Changes in hydrological conditions are expected and may alter carbon cycling peatlands. Peat aeration with water table change has not commonly been investigated, the is often assumed to constitute oxic‐anoxic boundary peat. We analyzed temperature, moisture, oxygen (O 2 ), dioxide (CO ) concentrations profiles of a temperate fen during two seasons. A drying‐rewetting cycle flooding were induced compared controls. The response moisture position varied greatly was related gradients peat...
Abstract. Climate change induced drying and flooding may alter the redox conditions of organic matter decomposition in peat soils. The seasonal intermittent changes pore water solutes (NO3−, Fe2+, SO42−, H2S, acetate) dissolved soil gases (CO2, O2, CH4, H2) under natural table fluctuations were compared to response a reinforced fen peats. Oxygen penetration during dryings led CO2 CH4 degassing regeneration electron acceptors Fe3+ SO42−). Drying intensity controlled extent acceptor...
Permafrost stores globally significant amounts of carbon (C) which may start to decompose and be released the atmosphere in form dioxide (CO2) methane (CH4) as global warming promotes extensive thaw. This permafrost feedback climate is currently considered most important carbon-cycle missing from models. Predicting magnitude requires a better understanding how differences environmental conditions post-thaw, particularly hydrological conditions, control rate at C atmosphere. In sporadic...
Boreal peatlands are major sources of dissolved organic carbon (DOC) to downstream aquatic ecosystems, where it influences cycling and food web structure. Wildfire permafrost thaw alter peatland vegetation hydrology may affect the quantity chemical composition exported DOC. We studied influence wildfire on microbial photochemical lability near-surface porewater DOC, assessed through 7 d incubations. carried out these incubations in spring, summer, fall but only found differences spring when...
Abstract. Permafrost thaw in northern peatlands often leads to increased methane (CH4) emissions, but the underlying controls responsible for emissions and duration which they persist have yet be fully elucidated. We assessed how shifting environmental conditions affect microbial communities magnitude stable isotopic signature (δ13C) of CH4 along a thermokarst bog transect boreal western Canada. Thermokarst bogs develop following permafrost when dry, elevated peat plateaus collapse become...
The quantitative impact of intense drought and rewetting on gas exchange in ombrotrophic bogs is still uncertain. In particular, we lack studies investigating multitudes sites with different soil properties nitrogen (N) sulfur (S) deposition under consistent environmental conditions. We explored the timing magnitude change CO2 (Respiration, Gross Primary Production - GPP, Net Exchange NE) CH4 fluxes during an initial wet, a prolonged dry (~100 days), subsequent wet period (~230 days) at 12...
Abstract Permafrost thaw in northern peatlands causes collapse of permafrost peat plateaus and thermokarst bog development, with potential impacts on atmospheric greenhouse gas exchange. Here, we measured methane carbon dioxide fluxes over 3 years (including winters) using static chambers along two transects northwestern Canada, spanning young (~30 since thaw), intermediate mature bogs (~200 thaw). Young were wetter, warmer had more hydrophilic vegetation than bogs. Methane emissions...
The dynamics and composition of microbial communities in the aqueous phase a model wetland supplied with cis- trans-1,2-dichloroethenes (DCE)-contaminated groundwater was characterized. PCR-denaturing gradient gel electrophoresis analysis water samples obtained from different parts revealed that changes bacterial community structure coincided succession hydrochemical conditions wetland, oxic towards anoxic conditions. During this transition phase, appearance vinyl chloride ethene correlated...
Despite occupying a small fraction of the landscape, fluvial networks are disproportionately large emitters CO2 and CH4 , with potential to offset terrestrial carbon sinks. Yet extent this remains uncertain, because current estimates emissions often do not integrate beyond individual river reaches over entire network in complex landscapes. Here we studied broad patterns concentrations isotopic signatures 50 streams western boreal biome Canada, across an area 250,000 km2 . Our study...
Abstract Wildfire in boreal permafrost peatlands causes a thickening and warming of the seasonally thawed active layer, exposing large amounts soil carbon to microbial processes potential release as greenhouse gases. In this study, conducted discontinuous zone western Canada, we monitored thermal regime respiration throughout 2016 growing season at an unburned peat plateau two nearby plateaus that burned 16 9 years prior study. Maximum seasonal temperature 40 cm depth was 4 °C warmer sites,...
Abstract. As climate warming and precipitation increase at high latitudes, permafrost terrains across the circumpolar north are poised for intensified geomorphic activity sediment mobilization that expected to persist millennia. In previously glaciated terrain, ice-rich deposits associated with large stores of reactive mineral substrate. Over geological timescales, chemical weathering moderates atmospheric CO2 levels, raising prospect mass wasting driven by terrain consolidation following...
The spatial and temporal biogeochemical development of a model wetland loaded with cis- trans-1,2-dichloroethene contaminated groundwater was characterized over 430 days by hydrogeochemical compound-specific isotope analyses (CSIA). hydrogeochemistry dramatically changed time from oxic to strongly reducing conditions as emphasized increasing concentrations ferrous iron, sulfide, methane since day 225. δ13C values for trans- cis-DCE substantially the flow path correlated DCE removal. carbon...
Vast stores of millennial-aged soil carbon (MSC) in permafrost peatlands risk leaching into the contemporary cycle after thaw caused by climate warming or increased wildfire activity. Here we tracked export and downstream fate MSC from two peatland-dominated catchments subarctic Canada, one which was recently affected wildfire. We tested whether thermokarst bog expansion deepening seasonally thawed soils due to contributions waters. Despite being available for lateral transport, accounted...
Permafrost soils store huge amounts of organic carbon, which could be released if climate change promotes thaw.Currently, modelling studies predict that thaw in boreal regions is mainly sensitive to warming, rather than changes precipitation or vegetation cover.We evaluate this conclusion for North American forests using a detailed process-based model parameterised and 5 validated on field measurements.We show soil thermal regimes dominant forest types are controlled strongly by moisture...
Abstract Permafrost thaw in peatlands risks emitting vast stores of soil organic carbon (SOC) as greenhouse gases to the atmosphere, yet anoxic conditions and low peat quality may prevent rapid SOC loss. To assess differences anaerobic mineralization following vulnerability previously‐frozen peat, we incubated (5° 14°C) from 15 depths ⁓6 m cores different sites including an intact permafrost plateau thermokarst bogs that thawed ∼30 ∼200 years ago. Furthermore, a glucose‐addition experiment...
Abstract. Radiocarbon is a critical constraint on our estimates of the timescales soil carbon cycling that can aid in identifying mechanisms stabilization and destabilization, improve forecast response to management or environmental change. Despite wealth radiocarbon data has been reported over past 75 years, ability apply these global scale questions limited by capacity synthesis compare measurements generated using variety methods. Here we describe International Soil Database (ISRaD,...