Inorganic carbon-isotope distribution and budget in the Lake Hoare and Lake Fryxell basins, Taylor Valley, Antarctica

One of the unusual features of Lakes Fryxell and Hnare in Taylor Valley, southern Victoria Land, Antarctica, is their perennial ice cover. This ice cover limits gas exchange between the atmosphere and the lake water, and causesa very stable stratification of the lakes. We analyzed a series of water samples from profiles of these lakes and their tributaries for δ13C of the dissolved inorganic carbon (DIC) in order to qualify the carbon flux from the streams into the lakes, and to investigate the carbon cycling with in the lakes. Isotopic values in the uppermost waters (δ13C = +l.3‰ to 5.3‰ in Lake Hoare, +0.4‰ to +3.0‰ in Lake Fryxell) are close to the carbon-isotope values encountered in the streams feeding Lake Fryxell, but distinctively heavier than in streams feeding Lake Hoare (δ13C= — 2.3%n to 1.4%). These ratios are much heavier than ratios found in the moat that forms around the lakes injanuary February (δC = -10.1%). in the oxic photic zones of the lakes, photosynthesis clearly influences the isotopic composition, with layers of high productivity having enriched carbon-isotope signatures δ13C= +2.7‰ to +6.1‰). in both lakes, the isotopic values become lighter with depth, reaching minima of 3.2‰ and 4.0% in Lakes Fryxell and Hoare, respectively. These minima are caused by the microbial remineralization of isotopically light organic carbon. We present DIC flux calculations that help to interpret the isotopic distribution. For example, in Lake Hoare the higher utilization of CO2aq, and a substantially smaller inflow of CO2 from streams cause the heavier observed isotopic ratios. Differences in the hydrology and stream morphologies of the tributaries also greatly influence the carbon budgets of the basins.

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An Ablation Rate for Lake Fryxell, Victoria Land, Antarctica

Journal of Glaciology ◽

10.3189/s0022143000019110 ◽

1966 ◽

Vol 6 (43) ◽

pp. 129-133 ◽

Cited By ~ 1

Author(s):

R. A. Henderson ◽

W. M. Prebble ◽

R. A. Hoare ◽

K. B. Popplewell ◽

D. A. House ◽

...

Keyword(s):

Ablation Rate ◽

Ice Cover ◽

Katabatic Winds ◽

Taylor Valley ◽

Victoria Land ◽

Lake Fryxell ◽

Novel Method ◽

The Difference

AbstractThe average yearly net ablation rate on permanently ice-covered Lake Fryxell, Victoria Land, Antarctica, is 30 to 40 cm. This figure was calculated by a novel method utilizing a record of ablation which is incorporated in the ice cover of the lake. These values are higher than those measured on Ross Island 80 km. to the east; the difference in ablation rates for the two areas is attributed to the prevalence of katabatic winds in the climate of Taylor Valley. The Lake Fryxell ablation figure is applied to nearby Canada and Commonwealth Glaciers in the calculation of their ice budgets.

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An Ablation Rate for Lake Fryxell, Victoria Land, Antarctica

Journal of Glaciology ◽

10.1017/s0022143000019110 ◽

1966 ◽

Vol 6 (43) ◽

pp. 129-133 ◽

Cited By ~ 26

Author(s):

R. A. Henderson ◽

W. M. Prebble ◽

R. A. Hoare ◽

K. B. Popplewell ◽

D. A. House ◽

...

Keyword(s):

Ablation Rate ◽

Ice Cover ◽

Katabatic Winds ◽

Taylor Valley ◽

Victoria Land ◽

Lake Fryxell ◽

Novel Method ◽

The Difference

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Seawater-buffered diagenesis, destruction of carbon isotope excursions, and the composition of DIC in Neoproterozoic oceans

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1909570116 ◽

2019 ◽

Vol 116 (38) ◽

pp. 18874-18879 ◽

Cited By ~ 9

Author(s):

Paul F. Hoffman ◽

Kelsey G. Lamothe

Keyword(s):

Shallow Water ◽

Carbon Isotope ◽

Deep Sea ◽

Inorganic Carbon ◽

Dissolved Inorganic Carbon ◽

Open Ocean ◽

Carbonate Sediments ◽

Carbonate Platforms ◽

Mg Isotopes ◽

Marine Platform

Carbonate sediments of nonglacial Cryogenian (659 to 649 Ma) and early Ediacaran (635 to 590 Ma) age exhibit large positive and negative δ13Ccarb excursions in a shallow-water marine platform in northern Namibia. The same excursions are recorded in fringing deep-sea fans and in carbonate platforms on other paleocontinents. However, coeval carbonates in the upper foreslope of the Namibian platform, and to a lesser extent in the outermost platform, have relatively uniform δ13Ccarb compositions compatible with dissolved inorganic carbon (DIC) in the modern ocean. We attribute the uniform values to fluid-buffered diagenesis that occurred where seawater invaded the sediment in response to geothermal porewater convection. This attribution, which is testable with paired Ca and Mg isotopes, implies that large δ13Ccarb excursions observed in Neoproterozoic platforms, while sedimentary in origin, do not reflect the composition of ancient open-ocean DIC.

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Interlaboratory test for stable carbon isotope analysis of dissolved inorganic carbon in geothermal fluids

Rapid Communications in Mass Spectrometry ◽

10.1002/rcm.8685 ◽

2020 ◽

Vol 34 (9) ◽

Author(s):

Mahendra P. Verma ◽

Robert Geldern ◽

Matheus C. Carvalho ◽

Fausto Grassa ◽

Antonio Delgado‐Huertas ◽

...

Keyword(s):

Carbon Isotope ◽

Inorganic Carbon ◽

Dissolved Inorganic Carbon ◽

Stable Carbon Isotope ◽

Isotope Analysis ◽

Stable Carbon ◽

Geothermal Fluids ◽

Interlaboratory Test ◽

Stable Carbon Isotope Analysis ◽

Carbon Isotope Analysis

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Measurements of the stable carbon isotope composition of dissolved inorganic carbon in the northeastern Atlantic and Nordic Seas during summer 2012

Earth System Science Data ◽

10.5194/essd-7-127-2015 ◽

2015 ◽

Vol 7 (1) ◽

pp. 127-135 ◽

Cited By ~ 8

Author(s):

M. P. Humphreys ◽

E. P. Achterberg ◽

A. M. Griffiths ◽

A. McDonald ◽

A. J. Boyce

Keyword(s):

Carbon Isotope ◽

Inorganic Carbon ◽

Dissolved Inorganic Carbon ◽

Isotope Composition ◽

Stable Carbon Isotope ◽

Carbon Isotope Composition ◽

Stable Carbon ◽

Nordic Seas ◽

Stable Carbon Isotope Composition ◽

Northeastern Atlantic

Abstract. The stable carbon isotope composition of dissolved inorganic carbon (δ13CDIC) in seawater was measured in a batch process for 552 samples collected during two cruises in the northeastern Atlantic and Nordic Seas from June to August 2012. One cruise was part of the UK Ocean Acidification research programme, and the other was a repeat hydrographic transect of the Extended Ellett Line. In combination with measurements made of other variables on these and other cruises, these data can be used to constrain the anthropogenic component of dissolved inorganic carbon (DIC) in the interior ocean, and to help to determine the influence of biological carbon uptake on surface ocean carbonate chemistry. The measurements have been processed, quality-controlled and submitted to an in-preparation global compilation of seawater δ13CDIC data, and are available from the British Oceanographic Data Centre. The observed δ13CDIC values fall in a range from −0.58 to +2.37 ‰, relative to the Vienna Pee Dee Belemnite standard. The mean of the absolute differences between samples collected in duplicate in the same container type during both cruises and measured consecutively is 0.10 ‰, which corresponds to a 1σ uncertainty of 0.09 ‰, and which is within the range reported by other published studies of this kind. A crossover analysis was performed with nearby historical δ13CDIC data, indicating that any systematic offsets between our measurements and previously published results are negligible. Data doi:10.5285/09760a3a-c2b5-250b-e053-6c86abc037c0 (northeastern Atlantic), doi:10.5285/09511dd0-51db-0e21-e053-6c86abc09b95 (Nordic Seas).

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The DIC carbon isotope evolutions during CO2 bubbling: implications for ocean acidification laboratory culture

10.31223/x5334w ◽

2022 ◽

Author(s):

Hongrui Zhang ◽

Ismael Torres-Romero ◽

Pien Anjewierden ◽

Madalina Jaggi ◽

Heather Stoll

Keyword(s):

Ocean Acidification ◽

Carbon Isotope ◽

Inorganic Carbon ◽

Dissolved Inorganic Carbon ◽

Carbon Isotope Ratio ◽

Laboratory Culture ◽

Total Alkalinity ◽

Isotopic Tracers ◽

Physiological Processes ◽

Isotope Equilibrium

Ocean acidification increases pCO2 and decreases pH of seawater and its impact on marine organisms has emerged as a key research focus. In addition to directly measured variables such as growth or calcification rate, stable isotopic tracers such as carbon isotopes have also been used to more completely understand the physiological processes contributing to the response of organisms to ocean acidification. To simulate ocean acidification in laboratory cultures, direct bubbling of seawater with CO2 has been a preferred method because it adjusts pCO2 and pH without altering total alkalinity. Unfortunately, the carbon isotope equilibrium between seawater and CO2 gas has been largely ignored so far. Frequently, the dissolved inorganic carbon (DIC) in the initial seawater culture has a distinct 13C/12C ratio which is far from the equilibrium expected with the isotopic composition of the bubbled CO2. To evaluate the consequences of this type of experiment for isotopic work, we measured the carbon isotope evolutions in two chemostats during CO2 bubbling and composed a numerical model to simulate this process. The isotopic model can predict well the carbon isotope ratio of dissolved inorganic carbon evolutions during bubbling. With help of this model, the carbon isotope evolution during a batch and continuous culture can be traced dynamically improving the accuracy of fractionation results from laboratory culture. Our simulations show that if not properly accounted for in experimental or sampling design, many typical culture configurations involving CO2 bubbling can lead to large errors in estimated carbon isotope fractionation between seawater and biomass or biominerals, consequently affecting interpretations and hampering comparisons among different experiments. Therefore, we describe the best practices on future studies working with isotope fingerprinting in the ocean acidification background.

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