scholarly journals Alkenone isotopes show evidence of active carbon concentrating mechanisms in coccolithophores as aqueous carbon dioxide concentrations fall below 7 µmol L<sup>−1</sup>

2021 ◽  
Vol 18 (3) ◽  
pp. 1149-1160
Author(s):  
Marcus P. S. Badger
Keyword(s):  
Carbon Dioxide ◽  
Cell Membrane ◽  
Ice Core ◽  
Co2 Concentration ◽  
Global Ocean ◽  
Carbon Dioxide Concentrations ◽  
Show Evidence ◽  
Carbon Concentrating Mechanisms ◽  
Through Diffusion ◽  
The Relationship

Abstract. Coccolithophores and other haptophyte algae acquire the carbon required for metabolic processes from the water in which they live. Whether carbon is actively moved across the cell membrane via a carbon concentrating mechanism, or passively through diffusion, is important for haptophyte biochemistry. The possible utilization of carbon concentrating mechanisms also has the potential to over-print one proxy method by which ancient atmospheric CO2 concentration is reconstructed using alkenone isotopes. Here I show that carbon concentrating mechanisms are likely used when aqueous carbon dioxide concentrations are below 7 µmol L−1. I compile published alkenone-based CO2 reconstructions from multiple sites over the Pleistocene and recalculate them using a common methodology, which allows comparison to be made with ice core CO2 records. Interrogating these records reveals that the relationship between proxy CO2 and ice core CO2 breaks down when local aqueous CO2 concentration falls below 7 µmol L−1. The recognition of this threshold explains why many alkenone-based CO2 records fail to accurately replicate ice core CO2 records, and it suggests the alkenone proxy is likely robust for much of the Cenozoic when this threshold was unlikely to be reached in much of the global ocean.

scholarly journals Alkenone isotopes show evidence of active carbon concentrating mechanisms in coccolithophores as aqueous carbon dioxide concentrations fall below 7 μmol L<sup>−1</sup>

2020 ◽  
Author(s):  
Marcus P. S. Badger
Keyword(s):  
Carbon Dioxide ◽  
Cell Membrane ◽  
Ice Core ◽  
Co2 Concentration ◽  
Global Ocean ◽  
Carbon Dioxide Concentrations ◽  
Show Evidence ◽  
Carbon Concentrating Mechanisms ◽  
Through Diffusion ◽  
The Relationship

Abstract. Coccolithophores and other haptophyte algae acquire the carbon required for metabolic processes from the water in which they live. Whether carbon is actively moved across the cell membrane via a carbon concentrating mechanism, or passively through diffusion, is important for haptophyte biochemistry. The possible utilisation of carbon concentrating mechanisms also has the potential to over-print one proxy method by which ancient atmospheric CO2 is reconstructed using alkenone isotopes. Here I show that carbon concentrating mechanisms are likely used when aqueous carbon dioxide concentrations are below 7 μmol L−1. I use published alkenone based CO2 reconstructions from multiple sites over the Pleistocene, which allows comparison to be made with ice core CO2 records. Interrogating these records reveal that the relationship between proxy- and ice core-CO2 breaks down when local aqueous CO2 concentration falls below 7 μmol L−1. The recognition of this threshold explains why many alkenone based CO2 records fail to accurately replicate ice core CO2 records, and suggests the alkenone proxy is likely robust for much of the Cenozoic when this threshold was unlikely to be reached in much of the global ocean.

Correlations of methane and carbon dioxide concentrations from feedlot cattle as a predictor of methane emissions

2016 ◽  
Vol 56 (1) ◽  
pp. 108 ◽  
Author(s):  
Mei Bai ◽  
David W. T. Griffith ◽  
Frances A. Phillips ◽  
Travis Naylor ◽  
Stephanie K. Muir ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Concentration Ratio ◽  
Co2 Concentration ◽  
Feedlot Cattle ◽  
Mitigation Strategies ◽  
Co2 Production ◽  
Ch4 Emissions ◽  
Carbon Dioxide Concentrations ◽  
Carbon Dioxide Co2 ◽  
Animal Diet

Accurate measurements of methane (CH4) emissions from feedlot cattle are required for verifying greenhouse gas (GHG) accounting and mitigation strategies. We investigate a new method for estimating CH4 emissions by examining the correlation between CH4 and carbon dioxide (CO2) concentrations from two beef cattle feedlots in Australia representing southern temperate and northern subtropical locations. Concentrations of CH4 and CO2 were measured at the two feedlots during summer and winter, using open-path Fourier transform infrared spectroscopy. There was a strong correlation for the concentrations above background of CH4 and CO2 with concentration ratios of 0.008 to 0.044 ppm/ppm (R2 >0.90). The CH4/CO2 concentration ratio varied with animal diet and ambient temperature. The CH4/CO2 concentration ratio provides an alternative method to estimate CH4 emissions from feedlots when combined with CO2 production derived from metabolisable energy or heat production.

scholarly journals Carbon dioxide measurements in the nocturnal boundary layer over Amazonian forest

1999 ◽  
Vol 3 (1) ◽  
pp. 39-53 ◽  
Author(s):  
A. D. Culf ◽  
G. Fisch ◽  
Y. Malhi ◽  
R. Carvalho Costa ◽  
A. D. Nobre ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Boundary Layer ◽  
Carbon Dioxide Concentration ◽  
Surface Flux ◽  
Co2 Concentration ◽  
Early Morning ◽  
Nocturnal Boundary Layer ◽  
Maximum Height ◽  
Carbon Dioxide Concentrations ◽  
The Difference

Abstract. Measurements of carbon dioxide concentration, temperature and windspeed were made in the nocturnal boundary layer over a tropical forest near Manaus, Brazil using a tethered balloon system. The measurements were made up to a maximum height of 300 m on ten consecutive nights in November 1995. Simultaneous surface flux and in-canopy concentration measurements were made at the surface close to the site. The observation period included several different types of conditions. Generally strong windshear and relatively weak temperature gradients prevented the formation of a strong capping inversion to the nocturnal boundary layer. On some nights, however, the inversion was sufficiently strong that the CO2 concentration at 100 m above the surface exceeded 400 ppm. The concentration within the canopy was largely controlled by the presence of an inversion very close to the canopy surface. The temperature and wind profiles are contrasted with conditions in Randônia, Brazil, where the windshear was found to be weaker and higher carbon dioxide concentrations were observed in the early morning. The difference in carbon dioxide concentrations in the nocturnal boundary layer between dusk and dawn is used to estimate the regional nighttime flux of carbon dioxide. The value obtained generally exceeds the measured surface flux and sometimes exceeds the sum of the surface flux and the in-canopy storage made at the tower site. The reasons for the discrepancy are not clear; either one of the methods is in error or the regional carbon dioxide budget differs significantly from the local budget measured at the tower site.

scholarly journals A Model to Account for Potential Correlations Between Growth of Loblolly Pine and Changing Ambient Carbon Dioxide Concentrations

2003 ◽  
Vol 27 (4) ◽  
pp. 279-284 ◽  
Author(s):  
James A. Westfall ◽  
Ralph L. Amateis
Keyword(s):  
Carbon Dioxide ◽  
Loblolly Pine ◽  
Atmospheric Carbon Dioxide ◽  
Management Strategies ◽  
Co2 Concentration ◽  
Site Index ◽  
Growth And Yield ◽  
Site Quality ◽  
Carbon Dioxide Concentrations ◽  
Carbon Dioxide Co2

Abstract Continuously increasing concentrations of atmospheric carbon dioxide (CO2) may be leading to enhanced growth rates for loblolly pine. In order to plan effectively silvicultural regimes and harvesting schedules, managers of loblolly pine plantations may wish to account for these potential changes when making growth and yield projections. Data from 94 unthinned plots across the Southeast were used to develop an equation that utilizes change in ambient CO2 concentration and initial site quality to predict change in site index (ΔSI). For a given change in CO2 concentration, a greater increase in site index is afforded to lower quality sites. The ΔSI equation was incorporated into a loblolly pine growth model. Simulations with and without site index adjustments were performed and plot volume estimates were compared to observed values. Mean percent residual dropped from 9.7% with no adjustment to -0.5% when ΔSI was employed. Forest managers can use this model to evaluate how possible CO2-induced growth increases may affect long-term timber yields and management strategies. South. J. Appl. For. 27(4):279–284.

scholarly journals Investigating Increased CO2 concentration on the pH of various plant species

2021 ◽  
Author(s):  
Joshua Schafer ◽  
Troy Puga ◽  
Pearce Harris ◽  
Nora Strasser ◽  
Gary Branum ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Carbonic Acid ◽  
Co2 Concentration ◽  
Steady Increase ◽  
Carbon Dioxide Absorption ◽  
Romaine Lettuce ◽  
Excess Carbon ◽  
Carbon Dioxide Concentrations ◽  
Consistent Increase ◽  
Carbon Dioxide Levels

The concept of bioremediation is quickly becoming the norm in the resolution of environmental issues. The steady increase in carbon dioxide levels, as documented by NASA, inspired scientists to engineer plants to absorb excess carbon dioxide from the atmosphere. Here, we have explored the consequences of the uptake of excess carbon dioxide by select plants. Carbon dioxide dissolves in water to produce carbonic acid, which dissociates to yield H+ ions. We hypothesized that increased carbon dioxide absorption results in decrease in pH of plant sap. Three plants (Byophyllum pinnatum, Romaine Lettuce and Nevada Lettuce), exposed to increased carbon dioxide concentrations (15%), demonstrated a consistent increase in pH towards alkalinity compared to control plants. Based on the outcome being opposite of what we have hypothesized, our results suggest Byophyllum pinnatum, Romaine lettuce and Nevada lettuce, all have a unique homeostatic system to prevent over-absorption of carbon dioxide in a carbon dioxide-rich environment.

Ammonium application mitigates the effects of elevated carbon dioxide on the carbon/nitrogen balance of Phoebe bournei seedlings

2021 ◽  
Author(s):  
Xiao Wang ◽  
Xiaoli Wei ◽  
Gaoyin Wu ◽  
Shengqun Chen
Keyword(s):  
Carbon Dioxide ◽  
Enzyme Activities ◽  
Atmospheric Carbon Dioxide ◽  
Global Climate ◽  
Co2 Concentration ◽  
Rubisco Activase ◽  
Plant Responses ◽  
N Metabolism ◽  
C And N ◽  
Phoebe Bournei

Abstract The study of plant responses to increases in atmospheric carbon dioxide (CO2) concentration is crucial to understand and to predict the effect of future global climate change on plant adaptation and evolution. Increasing amount of nitrogen (N) can promote the positive effect of CO2, while how N forms would modify the degree of CO2 effect is rarely studied. The aim of this study was to determine whether the amount and form of nitrogen (N) could mitigate the effects of elevated CO2 (eCO2) on enzyme activities related to carbon (C) and N metabolism, the C/N ratio, and growth of Phoebe bournei (Hemsl.) Y.C. Yang. One-year-old P. bournei seedlings were grown in an open-top air chamber under either an ambient CO2 (aCO2) (350 ± 70 μmol•mol−1) or an eCO2 (700 ± 10 μmol•mol−1) concentration and cultivated in soil treated with either moderate (0.8 g per seedling) or high applications (1.2 g per seedling) of nitrate or ammonium. In seedlings treated with a moderate level of nitrate, the activities of key enzymes involved in C and N metabolism (i.e., Rubisco, Rubisco activase and glutamine synthetase) were lower under eCO2 than under aCO2. By contrast, key enzyme activities (except GS) in seedlings treated with high nitrate or ammonium were not significantly different between aCO2 and eCO2 or higher under eCO2 than under aCO2. The C/N ratio of seedlings treated with moderate or high nitrate under eCO2was significantly changed compared with the seedlings grown under aCO2, whereas the C/N ratio of seedlings treated with ammonium was not significantly different between aCO2 and eCO2. Therefore, under eCO2, application of ammonium can be beneficial C and N metabolism and mitigate effects on the C/N ratio.

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