scholarly journals Hydrogen, Oxygen, and Carbon Isotope Ratios of Cellulose from Submerged Aquatic Crassulacean Acid Metabolism and Non-Crassulacean Acid Metabolism Plants

1984 ◽  
Vol 76 (1) ◽  
pp. 68-70 ◽  
Author(s):  
Leonel Sternberg ◽  
Michael J. Deniro ◽  
Jon E. Keeley
Keyword(s):  
Carbon Isotope ◽  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Isotope Ratios ◽  
Carbon Isotope Ratios ◽  
Oxygen And Carbon Isotope

Degrees of crassulacean acid metabolism in tropical epiphytic and lithophytic ferns

1999 ◽  
Vol 26 (8) ◽  
pp. 749 ◽  
Author(s):  
Joseph A.M. Holtum ◽  
Klaus Winter
Keyword(s):  
Carbon Isotope ◽  
Crassulacean Acid Metabolism ◽  
Acid Metabolism ◽  
Dark Period ◽  
Titratable Acidity ◽  
Isotope Ratios ◽  
Light Period ◽  
Co2 Uptake ◽  
Carbon Isotope Ratios ◽  
Net Co2 Uptake

Crassulacean acid metabolism (CAM) was observed in three species of tropical ferns, the epiphytes Microsorium punctatum and Polypodium crassifolium and the lithophyte Platycerium veitchii. Polypodium crassifolium and P. veitchii exhibited characteristics of weak CAM. Although no net nocturnal CO2 uptake was observed, the presence of CAM was inferred from nocturnal increases in titratable acidity of 4.7 and 4.1 µequiv (g fr wt)–1 respectively, a reduction in the rates of net CO2 evolution during the first half of the dark period, and the presence of a CAM-like decrease in net CO2 uptake during the early light period. In M. punctatum net CO2 uptake during the first half of the dark period was accompanied by an increase in titratable acidity of 39.2 µequiv (g fr wt)–1 and a pronounced reduction in net CO2 uptake during the early light period. When water was withheld from P. crassifolium and M. punctatum, net CO2 uptake during the light was reduced markedly but there was no change in the extent or patterns of CO2 exhange in the dark. As a consequence, the proportion of carbon gained due to CO2 fixation in the dark increased from 2.8 and 10% to 63.5 and 49.3%, respectively (100% being net CO2 uptake during the light plus the estimated CO2 uptake during the dark). After 9 days without added water, dark CO2 uptake was responsible for the maintenance of a net 24 h carbon gain in P. crassifolium. Platycerium veitchii, P. crassifolium and M. punctatum exhibited carbon isotope ratios of between –25.9 and –22.6‰ indicating that carbon isotope ratios may not, by themselves, be sufficient for the identification of weak CAM. We suggest that CAM may be more prevalent in tropical epiphytic and lithophytic ferns than currently envisaged.

Oxygen and carbon isotope ratios in the martian atmosphere

Icarus ◽  
2007 ◽  
Vol 192 (2) ◽  
pp. 396-403 ◽  
Author(s):  
Vladimir A. Krasnopolsky ◽  
Jean Pierre Maillard ◽  
Tobias C. Owen ◽  
Robert A. Toth ◽  
Michael D. Smith
Keyword(s):  
Carbon Isotope ◽  
Martian Atmosphere ◽  
Isotope Ratios ◽  
Carbon Isotope Ratios ◽  
Oxygen And Carbon Isotope

Variability of Indian monsoonal rainfall over the past 100 ka and its implication for C3–C4 vegetational change

2012 ◽  
Vol 77 (1) ◽  
pp. 159-170 ◽  
Author(s):  
Shailesh Agrawal ◽  
Prasanta Sanyal ◽  
Anindya Sarkar ◽  
Manoj Kumar Jaiswal ◽  
Koushik Dutta
Keyword(s):  
Carbon Isotope ◽  
Isotope Ratios ◽  
Ganga Plain ◽  
Carbon Isotope Ratios ◽  
Oxygen And Carbon Isotope ◽  
Vegetational Change ◽  
Time Period ◽  
Soil Carbonate ◽  
Maximum Decrease ◽  
Rainfall Variations

Oxygen and carbon isotope ratios of soil carbonate and carbon isotope ratios of soil organic matter (SOM) separated from three cores, Kalpi, IITK and Firozpur, of the Ganga Plain, India are used to reconstruct past rainfall variations and their effect on ambient vegetation. The δ18O values of soil carbonate (δ18OSC) analyzed from the cores range from −8.2 to −4.1‰. Using these variations in δ18OSC values we are able, for the first time, to show periodic change in rainfall amount between 100 and 18 ka with three peaks of higher monsoon at about 100, 40 and 25 ka. The estimation of rainfall variations using δ18O value of rainwater-amount effect suggests maximum decrease in rainfall intensity (~ 20%) during the last glacial maximum. The δ13C values of soil carbonate (δ13CSC) and SOM (δ13CSOM) range from −6.3 to + 1.6‰ and −28.9 to −19.4‰, respectively, implying varying proportions of C3 and C4 vegetations over the Ganga Plain during the last 100 ka. The comparison between monsoonal rainfall and atmospheric CO2 with vegetation for the time period 84 to 18 ka indicate that relative abundances of C3 and C4 vegetations were mainly driven by variations in monsoonal rainfall.

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