Filters: Tags: Carbon Flux (X) > Types: Journal Citation (X)
18 results (19ms)
Filters
Date Range
Extensions Types Contacts Categories Tag Types |
Riverine exports of organic and inorganic carbon (OC, IC) to oceans are intricately linked to processes occurring on land. Across high latitudes, thawing permafrost, alteration of hydrologic flow paths, and changes in vegetation may all affect this flux, with subsequent implications for regional and global carbon (C) budgets. Using a unique, multi-decadal dataset of continuous discharge coupled with water chemistry measurements for the Mackenzie River, we show major increases in dissolved OC (DOC) and IC (as alkalinity) fluxes since the early 1970s, for a watershed that covers 1.8 M km2 of northwestern Canada, and provides substantial inputs of freshwater and biogeochemical constituents to the Arctic Ocean. Over...
Categories: Publication;
Types: Journal Citation;
Tags: Alkalinity flux,
Arctic Ocean,
Carbon flux,
Dissolved organic carbon,
Mackenzie Drainage Basin,
Terrestrial carbon sequestration potential is widely considered as a realistic option for mitigating greenhouse gas emissions. However, this potential may be threatened by global changes including climate, land use, and management changes such as increased corn stover harvesting for rising production of cellulosic biofuel. Therefore, it is critical to investigate the dynamics of soil organic carbon (SOC) at regional or global scale. This study simulated the corn production and spatiotemporal changes of SOC in the U.S. Temperate Prairies, which covers over one-third of the U.S. corn acreage, using a biogeochemical model with multiple climate and land-use change projections. The corn production (either grain yield...
Categories: Publication;
Types: Journal Citation;
Tags: Carbon dynamics,
Carbon flux,
Carbon stock,
Soil carbon,
Soil organic carbon,
In forests, total belowground carbon (C) flux (TBCF) is a large component of the C budget and represents a critical pathway for delivery of plant C to soil. Reducing uncertainty around regional estimates of forest C cycling may be aided by incorporating knowledge of controls over soil respiration and TBCF. Photosynthesis, and presumably TBCF, declines with advancing tree size and age, and photosynthesis increases yet C partitioning to TBCF decreases in response to high soil fertility. We hypothesized that these causal relationships would result in predictable patterns of TBCF, and partitioning of C to TBCF, with natural variability in leaf area index (LAI), soil nitrogen (N), and tree height in subalpine forests...
Categories: Publication;
Types: Journal Citation;
Tags: Carbon flux,
Leaf area index,
Soil carbon,
Soil nitrogen,
Subalpine forests,
Dynamic tidal export of dissolved inorganic carbon (DIC) to the coastal ocean from highly productive intertidal marshes and its effects on seawater carbonate chemistry are thoroughly evaluated. The study uses a comprehensive approach by combining tidal water sampling of CO2parameters across seasons, continuous in situ measurements of biogeochemically-relevant parameters and water fluxes, with high-resolution modeling in an intertidal salt marsh of the U.S. northeast region. Salt marshes can acidify and alkalize tidal water by injecting CO2 (DIC) and total alkalinity (TA). DIC and TA generation may also be decoupled due to differential effects of marsh aerobic and anaerobic respiration on DIC and TA. As marsh DIC...
Categories: Publication;
Types: Journal Citation;
Tags: Carbon flux,
Coastal ocean,
Inorganic carbon,
Intertidal salt marsh,
Tidal marsh
We develop a new framework, based on Landsat time series data and forest inventories, to estimate the carbon in roundwood harvested from forest management activities, which will enter the HWP pool and remain stored in end uses and landfills. The approach keeps the distinction between the carbon from different types of roundwood sources, which allows for better integration with the regional HWP carbon lifetime information. We show that existing methods that are based on large scale regional/national values and linear interpolation of data gaps, can provide only very approximate carbon estimates. The model was applied to a US state using county level data, but can also suit different areas as long as sufficient harvest...
Categories: Publication;
Types: Journal Citation;
Tags: Carbon flux,
Forest management,
Harvested wood products,
Remote sensing
Inland water ecosystems dynamically process, transport, and sequester carbon. However, the transport of carbon through aquatic environments has not been quantitatively integrated in the context of terrestrial ecosystems. Here, we present the first integrated assessment, to our knowledge, of freshwater carbon fluxes for the conterminous United States, where 106 (range: 71–149) teragrams of carbon per year (TgC⋅y−1) is exported downstream or emitted to the atmosphere and sedimentation stores 21 (range: 9–65) TgC⋅y−1 in lakes and reservoirs. We show that there is significant regional variation in aquatic carbon flux, but verify that emission across stream and river surfaces represents the dominant flux at 69 (range:...
Categories: Publication;
Types: Journal Citation;
Tags: Aquatic carbon,
Carbon flux,
Conterminous United States,
Inland waters,
Terrestrial carbon
The Upper Mississippi River, engineered for river navigation in the 1930s, includes a series of low-head dams and navigation pools receiving elevated sediment and nutrient loads from the mostly agricultural basin. Using high-resolution, spatially resolved water quality sensor measurements along 1385 river kilometers, we show that primary productivity and organic matter accumulation affect river carbon dioxide and methane emissions to the atmosphere. Phytoplankton drive CO2to near or below atmospheric equilibrium during the growing season, while anaerobic carbon oxidation supports a large proportion of the CO2 and CH4 production. Reductions of suspended sediment load, absent of dramatic reductions in nutrients, will...
Categories: Publication;
Types: Journal Citation;
Tags: Basin scale controls,
C02 emissions,
CH4 emissions,
Carbon flux,
Upper Mississippi River
Inland waters are an important component of the global carbon cycle through transport, storage, and direct emissions of CO2 and CH4 to the atmosphere. Despite predictions of high physical gas exchange rates due to turbulent flows and ubiquitous supersaturation of CO2—and perhaps also CH4—patterns of gas emissions are essentially undocumented for high mountain ecosystems. Much like other headwater networks around the globe, we found that high-elevation streams in Rocky Mountain National Park, USA, were supersaturated with CO2 during the growing season and were net sources to the atmosphere. CO2 concentrations in lakes, on the other hand, tended to be less than atmospheric equilibrium during the open water season....
Categories: Publication;
Types: Journal Citation;
Tags: Carbon emissions,
Carbon flux,
Mountain streams and lakes
Temperate freshwater wetlands are among the most productive terrestrial ecosystems, stimulating interest in using restored wetlands as biological carbon sequestration projects for greenhouse gas reduction programs. In this study, we used the eddy covariance technique to measure surface energy carbon fluxes from a constructed, impounded freshwater wetland during two annual periods that were 8 years apart: 2002–2003 and 2010–2011. During 2010–2011, we measured methane (CH4) fluxes to quantify the annual atmospheric carbon mass balance and its concomitant influence on global warming potential (GWP). Peak growing season fluxes of latent heat and carbon dioxide (CO2) were greater in 2002–2003 compared to 2010–2011. In...
Categories: Publication;
Types: Journal Citation;
Tags: Carbon flux,
Carbon market verification protocols,
Temperate freshwater wetland,
Wetlands
Organic carbon (OC) burial in lacustrine sediments represents an important sink in the global carbon cycle; however, large-scale OC burial rates are poorly constrained, primarily because of the sparseness of available data sets. Here we present an analysis of OC burial rates in water bodies of the conterminous U.S. (CONUS) that takes advantage of recently developed national-scale data sets on reservoir sedimentation rates, sediment OC concentrations, lake OC burial rates, and water body distributions. We relate these data to basin characteristics and land use in a geostatistical analysis to develop an empirical model of OC burial in water bodies of the CONUS. Our results indicate that CONUS water bodies sequester...
Categories: Publication;
Types: Journal Citation;
Tags: Carbon flux,
Conterminous United States,
Lakes,
Organic carbon burial,
Reservoirs
Changes in vegetation and snow cover may lead to feedbacks to climate through changes in surface albedo and energy fluxes between the land and atmosphere. In addition to these biogeophysical feedbacks, biogeochemical feedbacks associated with changes in carbon (C)storage in the vegetation and soils may also influence climate. Here, using a transient biogeographic model (ALFRESCO) and an ecosystem model (DOS-TEM), we quantified the biogeophysical feedbacks due to changes in vegetation and snow cover across continuous permafrost to non-permafrost ecosystems in Alaska and northwest Canada. We also computed the changes in carbon storage in this region to provide a general assessment of the direction of the biogeochemical...
Categories: Publication;
Types: Journal Citation;
Tags: Alaska,
Atmospheric heating,
Boreal forest fire,
Carbon flux,
Carbon stock,
A nested sampling network on the Colorado (CR) and Missouri Rivers (MR) provided data to assess impacts of large-scale reservoir systems and climate on carbon export. The Load Estimator (LOADEST) model was used to estimate both dissolved inorganic and organic carbon (DIC and DOC) fluxes for a total of 22 sites along the main stems of the CR and MR. Both the upper CR and MR DIC and DOC fluxes increased longitudinally, but the lower CR fluxes decreased while the lower MRs continued to increase. We examined multiple factors through space and time that help explain these flux patterns. Seasonal variability in precipitation and temperature, along with site-level concentration versus discharge relationships proved to...
Categories: Publication;
Types: Journal Citation;
Tags: Carbon flux,
Central West,
Climate,
Intermontane West,
Longitudinal riverine carbon flux,
Projecting the spatiotemporal carbon dynamics of the Greater Yellowstone Ecosystem from 2006 to 2050
Climate change and the concurrent change in wildfire events and land use comprehensively affect carbon dynamics in both spatial and temporal dimensions. The purpose of this study was to project the spatial and temporal aspects of carbon storage in the Greater Yellowstone Ecosystem (GYE) under these changes from 2006 to 2050. We selected three emission scenarios and produced simulations with the CENTURY model using three General Circulation Models (GCMs) for each scenario. We also incorporated projected land use change and fire occurrence into the carbon accounting.
Categories: Publication;
Types: Journal Citation;
Tags: Carbon flux,
Carbon sequestration,
Carbon stock,
Climate change,
Greater Yellowstone Ecosystem,
* 1 Soils are one of the last great frontiers for biodiversity research and are home to an extraordinary range of microbial and animal groups. Biological activities in soils drive many of the key ecosystem processes that govern the global system, especially in the cycling of elements such as carbon, nitrogen and phosphorus. * 2 We cannot currently make firm statements about the scale of biodiversity in soils, or about the roles played by soil organisms in the transformations of organic materials that underlie those cycles. The recent UK Soil Biodiversity Programme (SBP) has brought a unique concentration of researchers to bear on a single soil in Scotland, and has generated a large amount of data concerning biodiversity,...
Categories: Publication;
Types: Citation,
Journal Citation;
Tags: 13C,
Functional Ecology,
Sourhope,
bacteria,
carbon flux,
Global management of wetlands to suppress greenhouse gas (GHG) emissions, facilitate carbon (C) sequestration, and reduce atmospheric CO2 concentrations while simultaneously promoting agricultural gains is paramount. However, studies that relate variability in CO2 and CH4 emissions at large spatial scales are limited. We investigated three-year emissions of soil CO2 and CH4 from the primary wetland types of the Liaohe Delta, China, by focusing on a total wetland area of 3287 km2. One percent is Suaeda salsa, 24% is Phragmites australis, and 75% is rice. While S. salsa wetlands are under somewhat natural tidal influence, P. australis and rice are managed hydrologically for paper and food, respectively. Total C emissions...
Categories: Publication;
Types: Journal Citation;
Tags: Carbon flux,
China,
Liaohe Delta,
Soil carbon,
Wetlands
Human activities have diverse and profound impacts on ecosystem carbon cycles. The Piedmont ecoregion in the eastern United States has undergone significant land use and land cover change in the past few decades. The purpose of this study was to use newly available land use and land cover change data to quantify carbon changes within the ecoregion. Land use and land cover change data (60-m spatial resolution) derived from sequential remotely sensed Landsat imagery were used to generate 960-m resolution land cover change maps for the Piedmont ecoregion. These maps were used in the Integrated Biosphere Simulator (IBIS) to simulate ecosystem carbon stock and flux changes from 1971 to 2010. Results: Results show that...
Categories: Publication;
Types: Journal Citation;
Tags: Carbon flux,
IBIS,
Land use and Land cover,
Piedmont Ecoregion
Hurricanes cause severe impacts on forest ecosystems in the United States. These events can substantially alter the carbon biogeochemical cycle at local to regional scales. We selected all tropical storms and more severe events that made U.S. landfall between 1900 and 2011 and used hurricane best track database, a meteorological model (HURRECON), National Land Cover Database (NLCD), U. S. Department of Agirculture Forest Service biomass dataset, and pre- and post-MODIS data to quantify individual event and annual biomass mortality. Our estimates show an average of 18.2 TgC/yr of live biomass mortality for 1900–2011 in the US with strong spatial and inter-annual variability. Results show Hurricane Camille in 1969...
Categories: Publication;
Types: Journal Citation;
Tags: Biogeochemistry,
Carbon cylce,
Carbon flux,
Ecological modelling,
Hurricanes
Coastal marshes take up atmospheric CO2 while emitting CO2, CH4, and N2O. This ability to sequester carbon (C) is much greater for wetlands on a per area basis than from most ecosystems, facilitating scientific, political, and economic interest in their value as greenhouse gas sinks. However, the greenhouse gas balance of Gulf of Mexico wetlands is particularly understudied. We describe the net ecosystem exchange (NEEc) of CO2 and CH4 using eddy covariance (EC) in comparison with fluxes of CO2, CH4, and N2O using chambers from brackish and freshwater marshes in Louisiana, USA. From EC, we found that 182 g C m−2 yr−1 was lost through NEEc from the brackish marsh. Of this, 11 g C m−2 yr−1 resulted from net CH4 emissions...
Categories: Publication;
Types: Journal Citation;
Tags: Carbon flux,
Deltaic marsh,
Eddy covariance,
Louisiana,
Pairing chamber techniques,
|