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

2019 ◽  
Vol 116 (38) ◽  
pp. 18874-18879 ◽  
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.

scholarly journals Sources of Carbon to Deep-Sea Corals

Radiocarbon ◽  
1989 ◽  
Vol 31 (03) ◽  
pp. 533-543 ◽  
Author(s):  
Sheila Griffin ◽  
Ellen R M Druffel
Keyword(s):  
Growth Rate ◽  
Organic Matter ◽  
Deep Sea ◽  
Inorganic Carbon ◽  
Sea Water ◽  
Dissolved Inorganic Carbon ◽  
Growth Rings ◽  
Time Histories ◽  
Visible Growth ◽  
Deep Sea Corals

Radiocarbon measurements in deep-sea corals from the Little Bahama Bank were used to determine the source of carbon to the skeletal matrices. Specimens of Lophelia, Gerardia, Paragorgia johnsoni and Corallium noibe were sectioned according to visible growth rings and/or stem diameter. We determined that the source of carbon to the corals accreting organic matter was primarily from surface-derived sources. Those corals that accrete a calcerous skeleton were found to obtain their carbon solely from dissolved inorganic carbon (DIC) in sea water from the depth at which the corals grew. These results, in conjunction with growth-rate studies using short-lived radioisotopes, support the use of deep-sea corals to reconstruct time histories of transient and non-transient tracers at depth in the oceans.

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

1998 ◽  
Vol 27 ◽  
pp. 685-689 ◽  
Author(s):  
Klaus Neumann ◽  
W. Berry Lyons ◽  
David J. Des Marais
Keyword(s):  
Carbon Isotope ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Ice Cover ◽  
Stable Stratification ◽  
High Productivity ◽  
Taylor Valley ◽  
Victoria Land ◽  
Lake Fryxell ◽  
Perennial Ice

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.

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

2015 ◽  
Vol 7 (1) ◽  
pp. 127-135 ◽  
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).

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

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.

Characteristics of concentrations and carbon isotope compositions of dissolved inorganic carbon in soil water under varying vegetations in karst watershed

2013 ◽  
Vol 33 (10) ◽  
pp. 3031-3038
Author(s):  
梁轩 LIANG Xuan ◽  
汪智军 WANG Zhijun ◽  
袁道先 YUAN Daoxian ◽  
杨平恒 YANG Pingheng ◽  
贺秋芳 HE Qiufang
Keyword(s):  
Soil Water ◽  
Carbon Isotope ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon

scholarly journals Quantitative Extraction of Dissolved Inorganic Carbon (as CO2) and Water by Vacuum Distillation from Sediments of the Unsaturated Zone for Carbon Isotope Analysis (13C and 14C)

Radiocarbon ◽  
2007 ◽  
Vol 49 (1) ◽  
pp. 83-94 ◽  
Author(s):  
I Carmi ◽  
J Kronfeld ◽  
Y Yechieli ◽  
D Yakir ◽  
M Stiller ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Unsaturated Zone ◽  
Vacuum Distillation ◽  
Isotope Fractionation ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Tap Water ◽  
Isotope Analysis ◽  
Standard Addition ◽  
Quantitative Extraction

Vacuum distillation is shown to be useful for the quantitative extraction of dissolved inorganic carbon (as CO2) and water from sediments of the unsaturated zone in the Coastal Aquifer of Israel. Several tests of vacuum extractions from tap water and sediments are presented, including standard addition, which show that the distillation procedure is quantitative, with minimal or no carbon isotope fractionation. The optimal temperature of the sediment during the extraction was also defined. Examples of vacuum extractions of sediments are shown.

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