Wildland fire ash enhances short-term CO2 flux from soil in a Southern African savannah

2021 ◽  
pp. 108334
Author(s):  
Carmen Sánchez-García ◽  
Cristina Santín ◽  
Stefan H. Doerr ◽  
Tercia Strydom ◽  
Emilia Urbanek
Keyword(s):  
Wildland Fire ◽  
Co2 Flux ◽  
Short Term

scholarly journals Biological CO2 Uptake and Upwelling Regulate the Air-Sea CO2 Flux in the Changjiang Plume Under South Winds in Summer

2021 ◽  
Vol 8 ◽  
Author(s):  
Dewang Li ◽  
Xiaobo Ni ◽  
Kui Wang ◽  
Dingyong Zeng ◽  
Bin Wang ◽  
...  
Keyword(s):  
Surface Waters ◽  
Carbon Sink ◽  
Co2 Flux ◽  
Co2 Uptake ◽  
Short Term ◽  
Biological Production ◽  
Initial Stage ◽  
Wind Event ◽  
Wind Events ◽  
Biogeochemical Parameters

The partial pressure of CO2 (pCO2) in the sea and the air-sea CO2 flux in plume waters are subject to interactions among biological production, horizontal advection, and upwelling under wind events. In this study, time series of pCO2 and other biogeochemical parameters in the dynamic Changjiang plume were presented to illuminate the controlling factors of pCO2 and the air-sea CO2 flux after a strong south wind event (July 23–24, maximum of 11.2 ms–1). The surface pCO2 decreased by 310 μatm (to 184 μatm) from July 24 to 26. Low-pCO2 waters (<200 μatm) were observed in the following 2 days. Corresponding chlorophyll a and dissolved oxygen (DO) increase, and a significant relationship between DO and npCO2 indicated that biological uptake drove the pCO2 decrease. The salinity of undersaturated-CO2 waters decreased by 3.57 (from 25.03 to 21.46) within 2 days (July 27–28), suggesting the offshore advection of plume waters in which CO2 had been biologically reduced. Four days after the wind event, the upwelling of high-CO2 waters was observed, which increased the pCO2 by 428 μatm (up to 584 μatm) within 6 days. Eight days after the onset of upwelling, the surface pCO2 started to decrease (from 661 to 346 μatm within 3 days), which was probably associated with biological production. Regarding the air-sea CO2 flux, the carbon sink of the plume was enhanced as the low-pCO2 plume waters were pushed offshore under the south winds. In its initial stage, the subsequent upwelling made the surface waters act as a carbon source to the atmosphere. However, the surface waters became a carbon sink again after a week of upwelling. Such short-term air-sea carbon fluxes driven by wind have likely occurred in other dynamic coastal waters and have probably induced significant uncertainties in flux estimations.

scholarly journals Measurements of CO<sub>2</sub>, its stable isotopes, O<sub>2</sub>/N<sub>2</sub>, and <sup>222</sup>Rn at Bern, Switzerland

2005 ◽  
Vol 5 (5) ◽  
pp. 8473-8506 ◽  
Author(s):  
P. Sturm ◽  
M. Leuenberger ◽  
F. L. Valentino ◽  
B. Lehmann ◽  
B. Ihly
Keyword(s):  
Co2 Flux ◽  
Urban Atmosphere ◽  
Precision Measurements ◽  
Short Term ◽  
Carbon And Oxygen Isotopes ◽  
Air Intake ◽  
One Year ◽  
Oxidation Ratio ◽  
Shed Light ◽  
Δ13c And Δ18o

Abstract. A one-year time series of continuous atmospheric CO2 measurements from Bern, Switzerland is presented. O2/N2 and Ar/N2 ratios as well as stable carbon and oxygen isotopes of CO2 and δ29N2, δ34O2 and δ36Ar were measured periodically in a continuous way during a one year period. Additionally, the 222Rn activity was measured during three months in the winter 2004. Using the correlation from short term fluctuations of CO2 and 222Rn we estimated a mean CO2 flux density between February 2004 and April 2004 in the region of Bern of 95±39 tC km−2 month−1. The continuous observations of carbon dioxide and associated tracers shed light on diurnal and seasonal patterns of the carbon cycle in an urban atmosphere. There is considerable variance in nighttime δ13C and δ18O of source CO2 throughout the year, however, with generally lower values in winter compared to summertime. The O2:CO2 oxidation ratio during the nighttime build-up of CO2 varies between −0.96 and −1.69 mol O2/mol CO2. Furthermore, Ar/N2 measurements showed that artifacts like thermal fractionation at the air intake are relevant for high precision measurements of atmospheric O2.

scholarly journals Sensitivity of the air–sea CO<sub>2</sub> exchange in the Baltic Sea and Danish inner waters to atmospheric short term variability

2014 ◽  
Vol 11 (12) ◽  
pp. 16993-17042
Author(s):  
A. S. Lansø ◽  
J. Bendtsen ◽  
J. H. Christensen ◽  
L. L. Sørensen ◽  
H. Chen ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Co2 Flux ◽  
Co2 Concentration ◽  
Co2 Exchange ◽  
Atmospheric Co2 ◽  
The Baltic Sea ◽  
Short Term ◽  
Transfer Velocity ◽  
The Baltic ◽  
Short Term Variability

Abstract. Minimising the uncertainties in estimates of air–sea CO2 exchange is an important step toward increasing the confidence in assessments of the CO2 cycle. Using an atmospheric transport model makes it possible to investigate the direct impact of atmospheric parameters on the air–sea CO2 flux along with its sensitivity to e.g. short-term temporal variability in wind speed, atmospheric mixing height and the atmospheric CO2 concentration. With this study the importance of high spatiotemporal resolution of atmospheric parameters for the air–sea CO2 flux is assessed for six sub-basins within the Baltic Sea and Danish inner waters. A new climatology of surface water partial pressure of CO2 (pCO2) has been developed for this coastal area based on available data from monitoring stations and underway pCO2 measuring systems. Parameterisations depending on wind speed were applied for the transfer velocity to calculate the air–sea CO2 flux. Two model simulations were conducted – one including short term variability in atmospheric CO2 (VAT), and one where it was not included (CAT). A seasonal cycle in the air–sea CO2 flux was found for both simulations for all sub-basins with uptake of CO2 in summer and release of CO2 to the atmosphere in winter. During the simulated period 2005–2010 the average annual net uptake of atmospheric CO2 for the Baltic Sea, Danish Straits and Kattegat was 287 and 471 Gg C yr-1 for the VAT and CAT simulations, respectively. The obtained difference of 184 Gg C yr-1 was found to be significant, and thus ignoring short term variability in atmospheric CO2 does have a sizeable effect on the air–sea CO2 exchange. The combination of the atmospheric model and the new pCO2 fields has also made it possible to make an estimate of the marine part of the Danish CO2 budget for the first time. A net annual uptake of 2613 Gg C yr-1 was found for the Danish waters. A large uncertainty is connected to the air–sea CO2 flux in particular caused by the transfer velocity parameterisation and the applied pCO2 climatology. However, the present study underlines the importance of including short term variability in the atmospheric CO2 concentration in future model studies of the air–sea exchange in order to minimise the uncertainty.

scholarly journals Measurements of CO<sub>2</sub>, its stable isotopes, O<sub>2</sub>/N<sub>2</sub>, and <sup>222</sup>Rn at Bern, Switzerland

2006 ◽  
Vol 6 (7) ◽  
pp. 1991-2004 ◽  
Author(s):  
P. Sturm ◽  
M. Leuenberger ◽  
F. L. Valentino ◽  
B. Lehmann ◽  
B. Ihly
Keyword(s):  
Co2 Flux ◽  
Urban Atmosphere ◽  
Precision Measurements ◽  
Short Term ◽  
Carbon And Oxygen Isotopes ◽  
Air Intake ◽  
One Year ◽  
Oxidation Ratio ◽  
Shed Light ◽  
Δ13c And Δ18o

Abstract. A one-year time series of atmospheric CO2 measurements from Bern, Switzerland, is presented. O2/N2 and Ar/N2 ratios as well as stable carbon and oxygen isotopes of CO2 and δ29N2, δ34O2 and δ36Ar were measured periodically during a one year period. Additionally, the 222Rn activity was measured during three months in the winter 2004. Using the correlation from short-term fluctuations of CO2 and 222Rn we estimated a mean CO2 flux density between February 2004 and April 2004 in the region of Bern of 95±39 tC km–2month–1. The continuous observations of carbon dioxide and associated tracers shed light on diurnal and seasonal patterns of the carbon cycle in an urban atmosphere. There is considerable variance in nighttime δ13C and δ18O of source CO2 throughout the year, however, with generally lower values in winter compared to summertime. The O2:CO2 oxidation ratio during the nighttime build-up of CO2 varies between –0.96 and –1.69 mol O2/mol CO2. Furthermore, Ar/N2 measurements showed that artifacts like thermal fractionation at the air intake are relevant for high precision measurements of atmospheric O2.

Economic optimisation of wildfire intervention activities

2010 ◽  
Vol 19 (5) ◽  
pp. 659 ◽  
Author(s):  
David T. Butry ◽  
Jeffrey P. Prestemon ◽  
Karen L. Abt ◽  
Ronda Sutphen
Keyword(s):  
Prescribed Fire ◽  
Wildland Fire ◽  
Optimal Solution ◽  
Education Programs ◽  
Short Term ◽  
Wildfire Management ◽  
Prevention Education ◽  
Fuels Management ◽  
Area Burned ◽  
Long Run

We describe how two important tools of wildfire management, wildfire prevention education and prescribed fire for fuels management, can be coordinated to minimise the combination of management costs and expected societal losses resulting from wildland fire. We present a long-run model that accounts for the dynamics of wildfire, the effects of fuels management on wildfire ignition risk and area burned, and the effects of wildfire prevention education on the ignition risk of human-caused, unintentional wildfires. Based on wildfire management activities in Florida from 2002 to 2007, we find that although wildfire prevention education and prescribed fire have different effects on timing and types of fires, the optimal solution is to increase both interventions. Prescribed fire affects whole landscapes and therefore reduces losses from all wildfire types (including lightning), whereas wildfire prevention education reduces only human-caused ignitions. However, prescribed fire offers a longer-term solution with little short-term flexibility. Wildfire prevention education programs, by comparison, are more flexible, both in time and space, and can respond to unexpected outbreaks, but with limited mitigation longevity. Only when used together in a coordinated effort do we find the costs and losses from unintentional wildfires are minimised.

Short-term effects of land consolidation of dryland-to-paddy conversion on soil CO2 flux

2021 ◽  
Vol 292 ◽  
pp. 112691
Author(s):  
Xiaoxiao Li ◽  
Nan Hui ◽  
Yongjun Yang ◽  
Jing Ma ◽  
Zhanbin Luo ◽  
...  
Keyword(s):  
Co2 Flux ◽  
Land Consolidation ◽  
Soil Co2 ◽  
Short Term ◽  
Soil Co2 Flux ◽  
Short Term Effects

scholarly journals Sensitivity of the air–sea CO<sub>2</sub> exchange in the Baltic Sea and Danish inner waters to atmospheric short-term variability

2015 ◽  
Vol 12 (9) ◽  
pp. 2753-2772 ◽  
Author(s):  
A. S. Lansø ◽  
J. Bendtsen ◽  
J. H. Christensen ◽  
L. L. Sørensen ◽  
H. Chen ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Co2 Flux ◽  
Co2 Concentration ◽  
Co2 Exchange ◽  
Atmospheric Co2 ◽  
The Baltic Sea ◽  
Short Term ◽  
Transfer Velocity ◽  
The Baltic ◽  
Short Term Variability

Abstract. Minimising the uncertainties in estimates of air–sea CO2 exchange is an important step toward increasing the confidence in assessments of the CO2 cycle. Using an atmospheric transport model makes it possible to investigate the direct impact of atmospheric parameters on the air–sea CO2 flux along with its sensitivity to, for example, short-term temporal variability in wind speed, atmospheric mixing height and atmospheric CO2 concentration. With this study, the importance of high spatiotemporal resolution of atmospheric parameters for the air–sea CO2 flux is assessed for six sub-basins within the Baltic Sea and Danish inner waters. A new climatology of surface water partial pressure of CO2 (pCO2w) has been developed for this coastal area based on available data from monitoring stations and on-board pCO2w measuring systems. Parameterisations depending on wind speed were applied for the transfer velocity to calculate the air–sea CO2 flux. Two model simulations were conducted – one including short-term variability in atmospheric CO2 (VAT), and one where it was not included (CAT). A seasonal cycle in the air–sea CO2 flux was found for both simulations for all sub-basins with uptake of CO2 in summer and release of CO2 to the atmosphere in winter. During the simulated period 2005–2010, the average annual net uptake of atmospheric CO2 for the Baltic Sea, Danish straits and Kattegat was 287 and 471 Gg C yr−1 for the VAT and CAT simulations, respectively. The obtained difference of 184 Gg C yr−1 was found to be significant, and thus ignoring short-term variability in atmospheric CO2 does have a sizeable effect on the air–sea CO2 exchange. The combination of the atmospheric model and the new pCO2w fields has also made it possible to make an estimate of the marine part of the Danish CO2 budget for the first time. A net annual uptake of 2613 Gg C yr−1 was found for the Danish waters. A large uncertainty is connected to the air–sea CO2 flux in particular caused by the transfer velocity parameterisation and the applied pCO2w climatology. However, as a significant difference of 184 Gg C yr−1 is obtained between the VAT and CAT simulations, the present study underlines the importance of including short-term variability in atmospheric CO2 concentration in future model studies of the air–sea exchange in order to minimise the uncertainty.

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