Nitrogen and phosphorus requirements of cotton and wheat under changing atmospheric CO2 concentrations

1993 ◽  
Vol 155-156 (1) ◽  
pp. 231-234 ◽  
Author(s):  
G. S. Rogers ◽  
L. Payne ◽  
P. Milham ◽  
J. Conroy
Keyword(s):  
Atmospheric Co2 ◽  
Nitrogen And Phosphorus ◽  
Co2 Concentrations ◽  
Atmospheric Co2 Concentrations ◽  
Phosphorus Requirements

Mineral composition of durum wheat grain and pasta under increasing atmospheric CO2 concentrations

2018 ◽  
Vol 242 ◽  
pp. 53-61 ◽  
Author(s):  
Romina Beleggia ◽  
Mariagiovanna Fragasso ◽  
Franco Miglietta ◽  
Luigi Cattivelli ◽  
Valeria Menga ◽  
...  
Keyword(s):  
Durum Wheat ◽  
Mineral Composition ◽  
Atmospheric Co2 ◽  
Wheat Grain ◽  
Co2 Concentrations ◽  
Atmospheric Co2 Concentrations

scholarly journals Heterogeneous CO<sub>2</sub> and CH<sub>4</sub> content of glacial meltwater from the Greenland Ice Sheet and implications for subglacial carbon processes

2021 ◽  
Vol 15 (3) ◽  
pp. 1627-1644
Author(s):  
Andrea J. Pain ◽  
Jonathan B. Martin ◽  
Ellen E. Martin ◽  
Åsa K. Rennermalm ◽  
Shaily Rahman
Keyword(s):  
Greenhouse Gas ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Mineral Weathering ◽  
Atmospheric Co2 ◽  
The Arctic ◽  
Co2 Concentrations ◽  
Geochemical Models ◽  
Atmospheric Co2 Concentrations ◽  
The Impact

Abstract. Accelerated melting of the Greenland Ice Sheet has increased freshwater delivery to the Arctic Ocean and amplified the need to understand the impact of Greenland Ice Sheet meltwater on Arctic greenhouse gas budgets. We evaluate subglacial discharge from the Greenland Ice Sheet for carbon dioxide (CO2) and methane (CH4) concentrations and δ13C values and use geochemical models to evaluate subglacial CH4 and CO2 sources and sinks. We compare discharge from southwest (a sub-catchment of the Isunnguata Glacier, sub-Isunnguata, and the Russell Glacier) and southern Greenland (Kiattut Sermiat). Meltwater CH4 concentrations vary by orders of magnitude between sites and are saturated with respect to atmospheric concentrations at Kiattut Sermiat. In contrast, meltwaters from southwest sites are supersaturated, even though oxidation reduces CH4 concentrations by up to 50 % during periods of low discharge. CO2 concentrations range from supersaturated at sub-Isunnguata to undersaturated at Kiattut Sermiat. CO2 is consumed by mineral weathering throughout the melt season at all sites; however, differences in the magnitude of subglacial CO2 sources result in meltwaters that are either sources or sinks of atmospheric CO2. At the sub-Isunnguata site, the predominant source of CO2 is organic matter (OM) remineralization. However, multiple or heterogeneous subglacial CO2 sources maintain atmospheric CO2 concentrations at Russell but not at Kiattut Sermiat, where CO2 is undersaturated. These results highlight a previously unrecognized degree of heterogeneity in greenhouse gas dynamics under the Greenland Ice Sheet. Future work should constrain the extent and controls of heterogeneity to improve our understanding of the impact of Greenland Ice Sheet melt on Arctic greenhouse gas budgets, as well as the role of continental ice sheets in greenhouse gas variations over glacial–interglacial timescales.

Homeostatic response of Aptian gymnosperms to changes in atmospheric CO2 concentrations

Geology ◽  
2021 ◽  
Author(s):  
Germán Mora ◽  
Ana M. Carmo ◽  
William Elliott
Keyword(s):  
Stomatal Closure ◽  
Carbon Assimilation ◽  
Atmospheric Co2 ◽  
The Past ◽  
A Value ◽  
Co2 Concentrations ◽  
Bulk Organic Matter ◽  
The Subject ◽  
Atmospheric Co2 Concentrations ◽  
Homeostatic Response

The sensitivity of plant carbon isotope fractionation (13Δleaf) to changes in atmospheric CO2 concentrations (Ca) is the subject of heavy debate, with some studies finding no sensitivity, while others show a strong dependency. We tested the hypothesis of photosynthetic homeostasis by using δ13C of n-alkanes, cuticles, and bulk organic matter of gymnosperm-rich rocks (Arundel Clay) from two sites deposited during the Aptian, a time that experienced significant Ca variations. Our results show no effect of Ca on 13Δleaf, and a relatively constant Ci/Ca (0.64 ± 0.04, 1σ; i—intercellular space), a value that is similar to that of modern gymnosperms. These results suggest that Aptian gymnosperms used homeostatic adjustments with rising Ca, probably involving increased carbon assimilation and/or stomatal closure, a response also found in modern gymnosperms. The similarity between Aptian and modern gymnosperms suggests that the processes responsible for regulating CO2 and water vapor exchange during photosynthesis have remained unaltered in gymnosperms for the past 128 m.y.

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