The impact of recycling of organic carbon on the stable carbon isotopic composition of dissolved inorganic carbon in a stratified marine system (Kyllaren fjord, Norway)

This study aims to validate the stable carbon isotopic composition (δ13C) of phytoplankton as a tool for detecting submarine leakages of anthropogenic CO2(g), since it is characterised by δ13C values significantly lower than the natural CO2 dissolved in oceans. Three culture experiments were carried out to investigate the changes in δ13C of the diatom Thalassiosira rotula during growth in an artificially modified medium (ASW). Three different dissolved inorganic carbon (DIC) concentrations were tested to verify if carbon availability affects phytoplankton δ13C. Simultaneously, at each experiment, T. rotula was cultured under natural DIC isotopic composition (δ13CDIC) and carbonate system conditions. The available DIC pool for diatoms grown in ASW was characterised by δ13CDIC values (−44.2 ± 0.9‰) significantly lower than the typical marine range. Through photosynthetic DIC uptake, microalgae δ13C rapidly changed, reaching significantly low values (until −43.4‰). Moreover, the different DIC concentrations did not affect the diatom δ13C, exhibiting the same trend in δ13C values in the three ASW experiments. The experiments prove that phytoplankton isotopic composition quickly responds to changes in the δ13C of the medium, making this approach a promising and low-impact tool for detecting CO2(g) submarine leakages from CO2(g) deposits.

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Environmental controls on the stable carbon isotopic composition of soil organic carbon: implications for modelling the distribution of C3and C4plants, Australia

Tellus B ◽

10.3402/tellusb.v60i4.16947 ◽

2008 ◽

Vol 60 (4) ◽

Author(s):

Jonathan G. Wynn ◽

Michael I. Bird

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Isotopic Composition ◽

Carbon Isotopic Composition ◽

Stable Carbon ◽

Carbon Isotopic ◽

Environmental Controls

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Evaluating Dissolved Inorganic Carbon Cycling in a Forested Lake Watershed Using Carbon Isotopes

Radiocarbon ◽

10.1017/s003382220006392x ◽

1992 ◽

Vol 34 (3) ◽

pp. 636-645 ◽

Cited By ~ 44

Author(s):

Ramon Aravena ◽

S. L. Schiff ◽

S. E. Trumbore ◽

P. J. Dillon ◽

Richard Elgood

Keyword(s):

Isotopic Composition ◽

Carbon Isotopes ◽

Inorganic Carbon ◽

Dissolved Inorganic Carbon ◽

Carbon Isotopic Composition ◽

Isotopic Fractionation ◽

Early Spring ◽

Late Winter ◽

Isotope Pattern ◽

Carbon Isotopic

Dissolved inorganic carbon (DIC) is the main acid buffer in forested lake watersheds in Canada. We used carbon isotopes (13C, 14C) to evaluate the production and cycling of DIC in an acid-sensitive lake watershed of the Precambrian Shield. Soil CO2, groundwater and stream DIC were characterized chemically and isotopically. Soil CO2 concentration profiles reflect both changes in production and in losses due to diffusion. δ13C soil CO2 profiles (δ13C values of −23‰ in summer, slightly enriched during the fall and −25%‰ during the winter) are a reflection of the isotopic composition of the sources and changes in isotopic fractionation due to diffusion. Carbon isotopic composition (13C, 14C) of the groundwater and stream DIC clearly indicate that weathering of silicates by soil CO2 is the main source of DIC in these watersheds. 14C data show that, in addition to recent groundwater, an older groundwater component with depleted 14C activity is also present in the bedrock. The carbon isotope pattern in the groundwater also implies that, besides the main springtime recharge events, contributions to the groundwater may also occur during late winter/early spring.

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