Ecosystem Carbon Fluxes Analyzed Using Eddy Covariance Technique

2021 ◽  
Author(s):  
Rachel Routly
Keyword(s):  
Carbon Dioxide ◽  
Eddy Covariance ◽  
Carbon Dioxide Emissions ◽  
Light Response ◽  
High Arctic ◽  
Physical Geography ◽  
Carbon Dioxide Exchange ◽  
Max Planck ◽  
Night Time ◽  
Partitioning Methods

Eddy covariance (EC) is an important measurement technique used in physical geography and atmospheric sciences to measure the exchange of carbon dioxide between an ecosystem and the atmosphere at a specific location. However, EC produces a net exchange of carbon dioxide yet research questions require an understanding of component fluxes, carbon dioxide uptake by plants through photosynthesis and carbon dioxide emissions due to plant and soil respiration.  There are two major methods to partition EC measurements into these component fluxes: night-time and day-time partitioning methods. In the night-time method, nighttime measurements are used to estimate daytime respiration and calculate photosynthesis as a residual and in the daytime method, a light response curve is created to estimate daytime respiration and photosynthesis.  This study investigates the benefits and drawbacks of these partitioning methods on two carbon dioxide exchange datasets from ecosystems in Canada.    The research sites were a) Mer Bleue, a peatland bog near Ottawa, Ontario and b) Cape Bounty, a high arctic tundra in Nunavut. By using a combination of the REddy-Proc software package, developed by the Max Planck Institute for Biogeochemistry, along with additional Matlab processing, the differences in photosynthesis and respiration due to partitioning methods are presented and discussed.

scholarly journals Carbon dioxide fluxes increase from day to night across European streams

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Katrin Attermeyer ◽  
Joan Pere Casas-Ruiz ◽  
Thomas Fuss ◽  
Ada Pastor ◽  
Sophie Cauvy-Fraunié ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Carbon Dioxide Emissions ◽  
Large Scale ◽  
Carbon Dioxide Flux ◽  
Time Of Day ◽  
Night Time ◽  
Carbon Dioxide Fluxes ◽  
Large Scale Assessment ◽  
Air Interface ◽  
Flux Variability

AbstractGlobally, inland waters emit over 2 Pg of carbon per year as carbon dioxide, of which the majority originates from streams and rivers. Despite the global significance of fluvial carbon dioxide emissions, little is known about their diel dynamics. Here we present a large-scale assessment of day- and night-time carbon dioxide fluxes at the water-air interface across 34 European streams. We directly measured fluxes four times between October 2016 and July 2017 using drifting chambers. Median fluxes are 1.4 and 2.1 mmol m−2 h−1 at midday and midnight, respectively, with night fluxes exceeding those during the day by 39%. We attribute diel carbon dioxide flux variability mainly to changes in the water partial pressure of carbon dioxide. However, no consistent drivers could be identified across sites. Our findings highlight widespread day-night changes in fluvial carbon dioxide fluxes and suggest that the time of day greatly influences measured carbon dioxide fluxes across European streams.

scholarly journals Vertical advection and nocturnal deposition of ozone over a boreal pine forest

2009 ◽  
Vol 9 (6) ◽  
pp. 2089-2095 ◽  
Author(s):  
Ü. Rannik ◽  
I. Mammarella ◽  
P. Keronen ◽  
T. Vesala
Keyword(s):  
Carbon Dioxide ◽  
Eddy Covariance ◽  
Turbulence Intensity ◽  
Carbon Dioxide Flux ◽  
Pine Forest ◽  
Night Time ◽  
Vertical Advection ◽  
Ozone Deposition ◽  
Storage Change ◽  
Ozone Sink

Abstract. Night-time ozone deposition for a Scots pine forest in Southern Finland was studied at the SMEAR II measurement station by evaluating the turbulent eddy covariance (EC), storage change and vertical advection fluxes. Similarly to night-time carbon dioxide flux, the eddy-covariance flux of ozone was decreasing with turbulence intensity (friction velocity), and storage change of the compound did not compensate the reduction (well-known night-time measurement problem). Accounting for vertical advection resulted in invariance of ozone deposition rate on turbulence intensity. This was also demonstrated for carbon dioxide, verified by independent measurements of NEE by chamber systems. The result highlights the importance of advection when considering the exchange measurements of any scalar. Analysis of aerodynamic and laminar boundary layer resistances by the model approach indicated that the surface resistance and/or chemical sink strength was limiting ozone deposition. The possible aerial ozone sink by known fast chemical reactions with sesquiterpenes and NO explain only a minor fraction of ozone sink. Thus the deposition is controlled either by stomatal uptake or surface reactions or both of them, the mechanisms not affected by turbulence intensity. Therefore invariance of deposition flux on turbulence intensity is expected also from resistance and chemical sink analysis.

Validation of modeled carbon-dioxide emissions from an urban neighborhood with direct eddy-covariance measurements

2011 ◽  
Vol 45 (33) ◽  
pp. 6057-6069 ◽  
Author(s):  
A. Christen ◽  
N.C. Coops ◽  
B.R. Crawford ◽  
R. Kellett ◽  
K.N. Liss ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Eddy Covariance ◽  
Carbon Dioxide Emissions ◽  
Urban Neighborhood ◽  
Eddy Covariance Measurements

scholarly journals Soil Nitrogen Dynamics Impact Carbon Exchange Processes in a High Arctic Wetland

2021 ◽  
Author(s):  
Jacqueline K.Y. Hung ◽  
Neal A. Scott ◽  
Paul M. Treitz
Keyword(s):  
Carbon Dioxide ◽  
Nutrient Availability ◽  
Soil Nitrogen ◽  
Nitrogen Availability ◽  
High Arctic ◽  
Carbon Dioxide Exchange ◽  
Arctic Ecosystems ◽  
Soil Nitrogen Availability ◽  
Environmental Controls ◽  
Exchange Processes

Abstract Increased soil nutrient availability, and associated increases in vegetation productivity, could create a negative feedback between Arctic ecosystems and the climate system, thereby reducing the contribution of Arctic ecosystems to future climate change. To predict whether this feedback will develop, it is important to understand the environmental controls over nutrient cycling in High Arctic ecosystems and their impact on carbon cycling processes. This study, conducted at the Cape Bounty Arctic Watershed Observatory, Melville Island, Nunavut, examined the environmental controls over soil nitrogen availability in a High Arctic wet sedge meadow and how they influenced carbon dioxide exchange processes from 2016-2018. Moisture variability across a seemingly homogenous wet sedge meadow allowed us to investigate nutrient availability and carbon dioxide exchange across naturally occurring moisture gradients over three growing seasons. The nature of the relationships (i.e., trends) between variables was consistent over the three years, but their magnitudes varied depending on climate conditions. Soil nitrogen availability, particularly ammonium, was higher in warmer years and wetter conditions and correlated positively with gross primary production (R 2 = 0.97) and net carbon dioxide uptake (R 2 = 0.88). Drier areas within the wetland had more nitrate availability, and this correlated negatively with net carbon dioxide exchange. Projections of a warmer, wetter Arctic and increased nutrient availability due to higher soil organic matter turnover suggest that northern wetlands will remain strong carbon dioxide sinks, or become stronger sinks, contributing to a negative feedback on the climate system.

scholarly journals Vertical advection and nocturnal deposition of ozone over a boreal pine forest

2008 ◽  
Vol 8 (5) ◽  
pp. 18437-18455 ◽  
Author(s):  
Ü. Rannik ◽  
P. Keronen ◽  
I. Mammarella ◽  
T. Vesala
Keyword(s):  
Carbon Dioxide ◽  
Eddy Covariance ◽  
Turbulence Intensity ◽  
Carbon Dioxide Flux ◽  
Pine Forest ◽  
Night Time ◽  
Vertical Advection ◽  
Ozone Deposition ◽  
Storage Change ◽  
Ozone Sink

Abstract. Night-time ozone deposition for a Scots pine forest in Southern Finland was studied at the SMEAR II measurement station by evaluating the turbulent eddy covariance (EC), storage change and vertical advection fluxes. Similarly to night-time carbon dioxide flux, the eddy-covariance flux of ozone was decreasing with turbulence intensity (friction velocity), and storage change of the compound did not compensate the reduction (well-known night-time measurement problem). Accounting for vertical advection resulted in invariance of ozone deposition rate on turbulence intensity. This was also demonstrated for carbon dioxide, verified by independent measurements of NEE by chamber systems. The result highlights the importance of advection when considering the exchange measurements of any scalar. Analysis of aerodynamic and laminar boundary layer resistances by the model approach indicated that the surface resistance and/or chemical sink strength was limiting ozone deposition. The possible aerial ozone sink by known fast chemical reactions with sesquiterpenes and NO explain only a minor fraction of ozone sink. Thus the deposition is controlled either by stomatal uptake or surface reactions or both of them, the mechanisms not affected by turbulence intensity. Therefore invariance of deposition flux on turbulence intensity is expected also from resistance and chemical sink analysis.

Methane and carbon dioxide emissions from two contrasting wetlands in the Okavango Delta, Botswana.

2020 ◽  
Author(s):  
Carole Helfter ◽  
Mangaliso Gondwe ◽  
Mike Murray-Hudson ◽  
Ute Skiba
Keyword(s):  
Carbon Dioxide ◽  
Soil Moisture ◽  
Eddy Covariance ◽  
Carbon Dioxide Emissions ◽  
Methane Emissions ◽  
Okavango Delta ◽  
Natural Soil ◽  
River Channels ◽  
Seasonal Wetland ◽  
Permanent Wetland

<p>We report on two years of continuous monitoring of methane (CH<sub>4</sub>) and carbon dioxide (CO<sub>2</sub>) emissions at two contrasting sites in the Okavango Delta, North-Western Botswana, an inland delta bordered by the Kalahari Desert. Approximately 60% of the annual water influx into the Okavango Delta results from seasonal river discharges originating in the Angolan Highlands, and the remainder comes from direct rainfall. 96-98% of the 16.1 billion m<sup>3</sup> entering the Delta annually are lost through evapo-transpiration (1500 mm.year<sup>-1</sup>). Flooding is gradual and it takes the pulsed influx ca. 4-5 months to travel the 250 km separating the inlet in Mohembo from the main outlet in Maun. The wetlands of the Okavango Delta are in pristine condition and can be separated into three categories: permanently flooded, seasonally flooded (3-6 months per year) and occasionally flooded (typically once per decade). </p><p>Two eddy-covariance systems were set up in August 2017, one at Guma Lagoon (18°57'53.01" S;  22°22'16.20" E) at the edge of an extensive papyrus bed in the permanently-flooded section of the delta, and the second one at Nxaraga on the SW edge of Chief’s Island (19°32'53'' S; 23°10'45'' E) in the seasonal floodplain. In addition, monthly measurements of methane and carbon dioxide fluxes were taken using a clear dynamic chamber at the Nxaraga site along transects chosen to span the natural soil moisture gradient (very dry to waterlogged soils).</p><p>The emissions of methane exhibited contrasting spatial and temporal patterns between sites. At the seasonal wetland, very low fluxes of CH<sub>4</sub> were typically observed from January to June. Emissions increased abruptly from July-August onwards after flood waters rewetted the flooplain in that area of the Delta. Throughout the year, local emission hotspots of CH<sub>4</sub> were observed along the vegetated river channels within the flux footprint of the eddy-covariance system, whereas CH<sub>4</sub> oxidation was recorded in persistently dry areas where the soil is sandy and salt-crusted. The chamber measurements corroborated the findings of the eddy-covariance measurements and soil moisture is likely the dominant control of methane fluxes at the seasonal wetland.</p><p>The methane emissions from the floating papyrus mat in the permanent wetland exhibited a marked seasonal cycle, characterised by relatively high emissions (of the order of 250 nmol.m<sup>-2</sup>.s<sup>-1</sup>; 2.5 larger than peak emissions recorded at the seasonal wetland) in the summer months (November-March) and minimum emissions in winter (typically 50 nmol.m<sup>-2</sup>.s<sup>-1</sup> in June-August). At the seasonal timescale, methane emissions were strongly correlated to the phenological cycle of papyrus (lowest emissions during the senescence phase), suggesting that plant-mediated transport is the dominant control. The annual budgets of CH<sub>4</sub> and CO<sub>2</sub> in the permanent wetland were estimated at 153.4 ± 27.9 tons.km<sup>-2</sup> (3835.0 ± 697.5 CO<sub>2</sub>-eq) and -874.0 ± 200.4 tons.km<sup>-2</sup> respectively, making the permanent wetland a potent net source of carbon to the atmosphere.</p>

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