scholarly journals Diel variations in the carbon isotope composition of respired CO<sub>2</sub> and associated carbon sources: a review of dynamics and mechanisms

2011 ◽  
Vol 8 (9) ◽  
pp. 2437-2459 ◽  
Author(s):  
C. Werner ◽  
A. Gessler
Keyword(s):  
Carbon Isotope ◽  
Isotope Fractionation ◽  
Temporal Dynamics ◽  
Carbon Allocation ◽  
Ecosystem Respiration ◽  
Isotope Composition ◽  
Carbon Sources ◽  
Mechanistic Explanation ◽  
Short Term ◽  
Theoretical Understanding

Abstract. Recent advances have improved our methodological approaches and theoretical understanding of post-photosynthetic carbon isotope fractionation processes. Nevertheless we still lack a clear picture of the origin of short-term variability in δ13C of respired CO2 (δ13Cres) and organic carbon fractions on a diel basis. Closing this knowledge gap is essential for the application of stable isotope approaches for partitioning ecosystem respiration, tracing carbon flow through plants and ecosystems and disentangling key physiological processes in carbon metabolism of plants. In this review we examine the short-term dynamics in δ13Cres and putative substrate pools at the plant, soil and ecosystem scales and discuss mechanisms, which might drive diel δ13Cres dynamics at each scale. Maximum reported variation in diel δ13Cres is 4.0, 5.4 and 14.8 ‰ in trunks, roots and leaves of different species and 12.5 and 8.1 ‰ at the soil and ecosystem scale in different biomes. Temporal variation in post-photosynthetic isotope fractionation related to changes in carbon allocation to different metabolic pathways is the most plausible mechanistic explanation for observed diel dynamics in δ13Cres. In addition, mixing of component fluxes with different temporal dynamics and isotopic compositions add to the δ13Cres variation on the soil and ecosystem level. Understanding short-term variations in δ13Cres is particularly important for ecosystem studies, since δ13Cres contains information on the fate of respiratory substrates, and may, therefore, provide a non-intrusive way to identify changes in carbon allocation patterns.

scholarly journals Diel variations in the carbon isotope composition of respired CO<sub>2</sub> and associated carbon sources: a review of dynamics and mechanisms

2011 ◽  
Vol 8 (2) ◽  
pp. 2183-2233 ◽  
Author(s):  
C. Werner ◽  
A. Gessler
Keyword(s):  
Carbon Isotope ◽  
Temporal Dynamics ◽  
Carbon Allocation ◽  
Ecosystem Respiration ◽  
Isotope Composition ◽  
Carbon Sources ◽  
Mechanistic Explanation ◽  
Short Term ◽  
Theoretical Understanding ◽  
Plant Soil

Abstract. Recent advances have improved our methodological approaches and theoretical understanding of post-photosynthetic carbon isotope fractionation. Nevertheless we still lack a clear picture of the origin of short-term variability in δ13C of respired CO2 (δ13Cres) and organic carbon fractions on a diel basis. However, closing this knowledge gap is essential for the application of stable isotope approaches for partitioning ecosystem respiration, tracing carbon flow through plants and ecosystems and disentangling key physiological processes in carbon metabolism of plants. In this review we examine the short-term dynamics in δ13Cres and putative substrate pools at the plant, soil and ecosystem scales and develop mechanistic explanations for diel δ13Cres dynamics at each scale. Maximum reported variation in diel δ13Cres is 4.0, 5.4 and 14.8‰ in trunks, roots and leaves of different species and 12.5 and 8.1‰ at the soil and ecosystem scale in different biomes. Temporal variation in post-photosynthetic fractionation related to changes in carbon allocation to different metabolic pathways is the most plausible mechanistic explanation for observed diel dynamics in δ13Cres. In addition, mixing of component fluxes with different temporal dynamics and isotopic compositions add to the δ13Cres variation on the soil and ecosystem level. Understanding short-term variations in δ13Cres is particularly important for ecosystem studies, since δ13Cres contains information on the fate of respiratory substrates, and may, therefore, provide a non-intrusive way to identify changes in carbon allocation patterns.

An experimental study of carbon-isotope fractionation between diet, hair, and feces of mammalian herbivores

2003 ◽  
Vol 81 (5) ◽  
pp. 871-876 ◽  
Author(s):  
Matt Sponheimer ◽  
Todd Robinson ◽  
Linda Ayliffe ◽  
Ben Passey ◽  
Beverly Roeder ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Carbon Isotopes ◽  
Isotope Fractionation ◽  
Cynodon Dactylon ◽  
Isotope Composition ◽  
Mammalian Herbivores ◽  
Carbon Isotope Fractionation ◽  
Tropical Environments ◽  
The Mean ◽  
Lama Pacos

The carbon-isotope composition of hair and feces offers a glimpse into the diets of mammalian herbivores. It is particularly useful for determining the relative consumption of browse and graze in tropical environments, as these foods have strongly divergent carbon-isotope compositions. Fecal δ13C values reflect the last few days consumption, whereas hair provides longer term dietary information. Previous studies have shown, however, that some fractionation occurs between dietary δ13C values and those of hair and feces. Accurate dietary reconstruction requires an understanding of these fractionations, but few controlled-feeding studies have been undertaken to investigate these fractionations in any mammalian taxa, fewer still in large mammalian herbivores. Here, we present data from the first study of carbon-isotope fractionation between diet, hair, and feces in multiple herbivore taxa. All taxa were fed pure alfalfa (Medicago sativa) diets for a minimum period of 6 months, at which point recently grown hair was shaved and analyzed for carbon isotopes. The mean observed diet–hair fractionation was +3.2‰, with a range of +2.7 to +3.5‰. We also examined diet–feces fractionation for herbivores on alfalfa and bermudagrass (Cynodon dactylon) feeds. The mean diet–feces fractionation for both diets was –0.8‰, with less fractionation for alfalfa (–0.6‰) than bermudagrass (–1.0‰). Fecal carbon turnover also varies greatly between taxa. When diets were switched, horse (Equus caballus) feces reflected the new diet within 60 h, but alpaca (Lama pacos) feces did not equilibrate with the new diet for nearly 200 h. Thus, fecal carbon isotopes provide far greater dietary resolution for hindgut-fermenting horses than foregut-fermenting alpacas.

Short-Term Measurements of Carbon Isotope Discrimination in Several C4 Species

1992 ◽  
Vol 19 (3) ◽  
pp. 263 ◽  
Author(s):  
SA Henderson ◽  
SV Caemmerer ◽  
GD Farquhar
Keyword(s):  
Carbon Isotope ◽  
Carbon Isotope Discrimination ◽  
Isotope Composition ◽  
Leaf Gas Exchange ◽  
Short Term ◽  
Isotope Discrimination ◽  
C4 Species ◽  
Linear Relationships ◽  
Partial Pressures ◽  
Wide Range

Carbon isotope discrimination (Δ) and leaf gas-exchange were measured simultaneously for a number of C4 species. Linear relationships were found between A and the ratio of intercellular to ambient partial pressures of CO2, pI/pa. These data were used to estimate the fraction of CO2 released by C4-acid decarboxylation in the bundle sheath, which subsequently leaks out to the mesophyll. We define this fraction as the leakiness of the system and it is also a measure of the extent to which phosphoenolpyruvate (PEP) carboxylations exceed ribulose 1,5-bisphosphate (RuBP) carboxylations. For Sorghum bicolor and Amaranthus edulis, leakiness was estimated at 0.2 and was constant over a wide range of irradiances (between 480 and 1600 μmol quanta m-2 s-1), intercellular CO2 pressures (between 30 and 350 μbar) and leaf temperatures (from 21�C to 34�C). At irradiances less than 240 μmol quanta m-2 s-1, leakiness appeared to increase. For a number of dicotyledonous and monocotyledonous species, of the various C4-decarboxylation types, leakiness was also estimated at 0.2. Contrary to expectation, amongst the 11 species examined, those with suberised lamellae did not show lower values of leakiness than those without suberised lamellae. For one NAD-ME and one PCK monocot, the estimates of leakiness were significantly higher at 0.30 and 0.25, respectively. Long-term discrimination (assessed from carbon isotope composition of leaf dry matter) did not correlate well with these short- term measures of discrimination. We suggest that this may be due to differences between species in fractionations occurring after photosynthesis.

Temporal dynamics of the carbon isotope composition in a Pinus sylvestris stand: from newly assimilated organic carbon to respired carbon dioxide

Oecologia ◽  
2008 ◽  
Vol 156 (4) ◽  
pp. 737-750 ◽  
Author(s):  
Naomi Kodama ◽  
Romain L. Barnard ◽  
Yann Salmon ◽  
Christopher Weston ◽  
Juan Pedro Ferrio ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Organic Carbon ◽  
Pinus Sylvestris ◽  
Carbon Isotope ◽  
Temporal Dynamics ◽  
Isotope Composition ◽  
Carbon Isotope Composition

Fractionation of Carbon Isotopes Between C-O-H Fluids and Melts in High Temperature Systems - Experimental Developments and Outlook

2020 ◽  
Author(s):  
Paul Petschnig ◽  
Nico Kueter ◽  
Max Schmidt
Keyword(s):  
High Temperature ◽  
Carbon Isotope ◽  
Isotope Fractionation ◽  
Isotope Composition ◽  
Stable Carbon Isotope ◽  
Experimental Studies ◽  
Magma Ocean ◽  
Carbon Isotope Fractionation ◽  
The Earth ◽  
Carbon Compounds

&lt;p&gt;Whether in gases or fluids, as solid or liquid carbonates, dissolved in magma or precipitated in its elemental form, carbon is present in every domain on Earth. The pathways of carbon across atmospheric-, surface-, subduction- and deeper reservoirs of our planet are complex, but can be illuminated by tracing stable carbon isotope ratios. Carbonates take a key role in connecting the surface to the deep carbon cycle. At moderate temperatures, carbon compounds dissolve in fluids, above 1000 &amp;#176;C, carbonates dissolve in or form melts and mobilize carbon inside the Earth. Towards the crust, carbon compounds tend to be oxidized (e.g. CO&lt;sub&gt;2&lt;/sub&gt;, CO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt;) while in the deeper mantle (&gt; 6-8 GPa), reduced states are dominant and cause carbonate reduction to CH&lt;sub&gt;4&lt;/sub&gt;, FeC or C dissolved in metal, graphite or diamond.&lt;sup&gt;[1]&lt;/sup&gt;&lt;/p&gt;&lt;p&gt;Recent experimental studies show large carbon isotope fractions at temperatures relevant for the mantle and early Earth environments (i.e. magma ocean surfaces). High temperature equilibrium fractionations have been constrained for CH&lt;sub&gt;4&lt;/sub&gt;-CO&lt;sub&gt;2&lt;/sub&gt;-CO&lt;sup&gt;[2]&lt;/sup&gt;, carbonate - graphite&lt;sup&gt;[3]&lt;/sup&gt;, and FeC - graphite&lt;sup&gt;[4]&amp;#160;&lt;/sup&gt;systems, most pairs amounting to a few &amp;#8240; at 1000 &lt;sup&gt;o&lt;/sup&gt;C. The recognition of kinetic carbon isotope fractionation during elemental carbon precipitation from C-O-H fluids revealed an unexpected high-temperature fractionation mechanism of ~5 &amp;#8240; for lower crust and mantle temperatures&lt;sup&gt;[5]&lt;/sup&gt;. In this light, carbon isotope fractionation may yield surprises in other experimentally underexplored processes.&amp;#160;&lt;/p&gt;&lt;p&gt;We present internally consistent experimental data on high temperature carbon isotope fractionation between carbonate or silicate melts, carbonate, C-O-H-fluids, carbide and graphite. Our results suggest that at high temperatures (&gt;1000 &amp;#176;C) the bonding environment of CO&lt;sub&gt;3&lt;/sub&gt;-groups (i.e. either in depolymerized silicate- or carbonate melt, in which carbon is anionic CO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt;, or as calcite) causes no resolvable differences leading to a universal &amp;#8710;&lt;sup&gt;13&lt;/sup&gt;C (CO&lt;sub&gt;2&lt;/sub&gt; -CO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt;) fractionation function. Similarly, we suggest that granitic melts with all carbon as molecular CO&lt;sub&gt;2&lt;/sub&gt;will show no isotope fractionation with an oxidized high temperature fluid. We further discuss challenges of experimental setups under reducing fO&lt;sub&gt;2&lt;/sub&gt;conditions and the intent of equilibrating silicate melt with reduced C-O-H-fluids, which is experimentally unconstrained and required to understand on one hand the magmatic outgassing of the Earth and how to reconstruct the source isotope composition, on the other hand in a magma-ocean setting, where reduced species are key for the evolution of primitive carbon reservoirs and their isotopic ratios (i.e. mantle carbon).&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;em&gt;&lt;sup&gt;&lt;span&gt;[1] &lt;/span&gt;&lt;/sup&gt;&lt;span&gt;Rohrbach, A., Schmidt, M. (2011).&amp;#160;Nature&amp;#160;472,&amp;#160;209&amp;#8211;212.&lt;sup&gt;[2] &lt;/sup&gt;Kueter, N., Schmidt, M. W., Lilley M. D., Bernasconi, S.M. (2019b). EPSL 506, p.64-75. &lt;sup&gt;[3] &lt;/sup&gt;Kueter, N., Lilley, M.D., Schmidt, M.W., Bernasconi, S.M. (2019a). &lt;/span&gt;&lt;span&gt;GCA253, 290&amp;#8211;306. &lt;sup&gt;[4] &lt;/sup&gt;Satish-Kumar, M., So, H., Yoshino, T., Kato, M., Hiroi, Y. (2011). &lt;/span&gt;&lt;span&gt;EPLS 310, 340&amp;#8211;348. &lt;sup&gt;[5]&lt;/sup&gt;Kueter, N., Schmidt, M. W., Lilley M. D., Bernasconi, S.M. (2020). EPSL 529,&lt;/span&gt;&lt;span&gt;115848&lt;/span&gt;&lt;/em&gt;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

scholarly journals Importance of short-term dynamics in carbon isotope ratios of ecosystem respiration (?13CR) in a Mediterranean oak woodland and linkage to environmental factors

2006 ◽  
Vol 172 (2) ◽  
pp. 330-346 ◽  
Author(s):  
Christiane Werner ◽  
Stephan Unger ◽  
João S. Pereira ◽  
Rodrigo Maia ◽  
Teresa S. David ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Carbon Isotope ◽  
Ecosystem Respiration ◽  
Isotope Ratios ◽  
Oak Woodland ◽  
Short Term ◽  
Carbon Isotope Ratios

scholarly journals Isotope Fractionation of Toluene: A Perspective to Characterise MicrobialIn SituDegradation

2002 ◽  
Vol 2 ◽  
pp. 1227-1234 ◽  
Author(s):  
H.H. Richnow ◽  
A. Vieth ◽  
M. Kastner ◽  
M. Gehre ◽  
R.U. Meckenstock
Keyword(s):  
Groundwater Flow ◽  
Carbon Isotope ◽  
Organic Contaminants ◽  
Isotope Fractionation ◽  
Isotope Composition ◽  
Flow Path ◽  
Groundwater Hydrology ◽  
Ground Water Flow ◽  
Fractionation Factor

A concept to assessin situbiodegradation of organic contaminants in aquifers is presented. The alteration of the carbon isotope composition of contaminants along the groundwater flow path indicates microbial degradation processes and can be used as an indicator forin situbiodegradation. The Rayleigh equation was applied to calculate the percentage of thein situbiodegradation (B[%]) using the change in the isotopic composition of contaminants (Rt/R0) along the ground water flow path and a kinetic carbon isotope fractionation factor (αC) derived from defined biodegradation experiments in the laboratory. When the groundwater hydrology is known and a representative source concentration (C0) for a groundwater flow path can be determined, the extent ofin situbiodegradation can be quantified.

Short-term changes in carbon isotope composition of soluble carbohydrates and starch: from canopy leaves to the root system

2006 ◽  
Vol 20 (4) ◽  
pp. 653-660 ◽  
Author(s):  
Sabine Göttlicher ◽  
Alexander Knohl ◽  
Wolfgang Wanek ◽  
Nina Buchmann ◽  
Andreas Richter
Keyword(s):  
Root System ◽  
Carbon Isotope ◽  
Isotope Composition ◽  
Carbon Isotope Composition ◽  
Soluble Carbohydrates ◽  
Short Term
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