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Arun Goyal - One of the best experts on this subject based on the ideXlab platform.

  • Dissolved Inorganic Carbon concentration mechanism in Chlamydomonas moewusii
    Plant Physiology and Biochemistry, 2002
    Co-Authors: Durba Ghoshal, H. David Husic, Arun Goyal
    Abstract:

    Abstract The Dissolved Inorganic Carbon concentrating mechanism(s) of Chlamydomonas moewusii CC 55 was compared with C. reinhardtii strain 137. C. moewusii is similar to C. reinhardtii with respect to maximal rates of photosynthetic oxygen evolution, CO 2 fixation, respiration, and the ability to efficiently concentrate Inorganic Carbon. C. moewusii has a low, but measurable amount of external Carbonic anhydrase (CA) that was not inhibited by acetazolamide (AZ), an inhibitor of periplasmic Carbonic anhydrase (pCA) in C. reinhardtii. The K 0.5 (CO 2 ) for air-grown C. moewusii is about 1 μM and the algal cells accumulated Dissolved Inorganic Carbon (DIC) to a level of about 1 mM in 60 s. AZ did not inhibit CO 2 fixation and the DIC accumulation by air-grown cells of C. moewusii . The K 0.5 (CO 2 ) for both species remains constant from pH 6.5 to 9.5 while K 0.5 (HCO 3 - ) increased logarithmically, which indicates that CO 2 is the apparent Inorganic Carbon species that enters the cells in both algae. Antiserum prepared against the 37 kDa peptide of pCA from C. reinhardtii was immunoreactive with polypeptides of 26, 28, and 32 kDa in C. moewusii . The periplasmic Carbonic anhydrase (pCA) activity is a part of the Dissolved Inorganic Carbon concentrating mechanism in C. reinhardtii , but C  moewusii accomplished Inorganic Carbon accumulation without an AZ-sensitive pCA.

  • Oxygen inhibition of Dissolved Inorganic Carbon uptake in unicellular green algae
    Phycological Research, 2001
    Co-Authors: Durba Ghoshal, Arun Goyal
    Abstract:

    SUMMARY Unicellular green algae have a Dissolved Inorganic Carbon (DIC) concentrating mechanism, commonly known as the DIC pump, to concentrate Inorganic Carbon into cells and chloroplasts. The DIC pump activity is normally measured as the K0.5(DIC) that equals the CO2 plus HCO3- concentration at a cited pH at which the rate of DIC-dependent photosynthetic O2 evolution is half-maximal, or by the amount of intra-cellular DIC accumulation in 15–60 s, using a limited amount of NaH14CO3, measured by the silicone oil cen-trifugation technique. The Dissolved oxygen in the assay inhibits or reduces the DIC uptake by the cells of unicellular green algae Chlamydomonas reinhardtii Dangeard, strain 137 and in a cell wall-less marine algae Dunaliella tertiolecta Butcher. The algal cells concentrated the highest amount of DIC when little or no oxygen was present in the assay medium. The results suggest that the amount of O2 and DIC must be carefully monitored before DIC-pump assay.

David M. Karl - One of the best experts on this subject based on the ideXlab platform.

  • Rising surface ocean Dissolved Inorganic Carbon at the Hawaii Ocean Time-series site
    Marine Chemistry, 1998
    Co-Authors: Christopher D. Winn, Fred T. Mackenzie, David M. Karl
    Abstract:

    Abstract Surface ocean Dissolved Inorganic Carbon (DIC) and titration alkalinity have been measured for 7 years as a part of the Hawaii Ocean Time-series (HOT) program. The time-series data set displays an interannual increase in the inventory of surface ocean DIC which we interpret as a response to increasing atmospheric Carbon dioxide concentrations. The rate of increase in surface ocean DIC at the open ocean HOT site is approximately 1 μ mol kg −1 yr −1 with a 95% confidence interval of 0.72 to 1.37 μ mol kg −1 yr −1 . This accumulation rate is consistent with the rate of increase predicted from the rise in boundary layer p CO 2 .

Are Olsen - One of the best experts on this subject based on the ideXlab platform.

  • nordic seas total Dissolved Inorganic Carbon data in carina
    Earth System Science Data, 2009
    Co-Authors: Are Olsen
    Abstract:

    Abstract. Water column data of Carbon and Carbon relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruises in the Arctic, Atlantic, and Southern Ocean have been retrieved and merged into a new database: CARINA (Carbon IN the Atlantic). The data have been subject to rigorous quality control (QC) in order to ensure highest possible quality and consistency. The data for most of the parameters included were examined in order to quantify systematic biases in the reported values, i.e. secondary quality control. Significant biases have been corrected for in the data products, i.e. the three merged files with measured, calculated and interpolated values for each of the three CARINA regions; the Arctic Mediterranean Seas (AMS), the Atlantic (ATL) and the Southern Ocean (SO). With the adjustments the CARINA database is consistent both internally as well as with GLODAP (Key et al., 2004) and is suitable for accurate assessments of, for example, oceanic Carbon inventories and uptake rates and for model validation. The Arctic Mediterranean Seas includes the Arctic Ocean and the Nordic Seas, and the quality control was carried out separately in these two areas. This contribution presents an account of the quality control of the total Dissolved Inorganic Carbon (TCO2) data from the Nordic Seas in CARINA. Out of the 35 cruises from the Nordic Seas included in CARINA, 25 had TCO2 data. The data from 7 of these were found to be of low quality and should not be used, thus the final CARINA data product contains TCO2 data from 18 cruises from the Nordic Seas. These data appear consistent to at least 4 μmol kg−1.

Johannes A. C. Barth - One of the best experts on this subject based on the ideXlab platform.

  • Spatial and temporal variations of pCO2, Dissolved Inorganic Carbon and stable isotopes along a temperate karstic watercourse
    Hydrological Processes, 2015
    Co-Authors: Robert Van Geldern, Peter Schulte, Michael Mader, Alfons Baier, Johannes A. C. Barth
    Abstract:

    This study investigated CO2 degassing and related Carbon isotope fractionation effects in the Wiesent River that drains a catchment in the karst terrain of the Franconian Alb, Southern Germany. The river was investigated by physico-chemical and stable isotope analyses of water and Dissolved Inorganic Carbon during all seasons along 65-km long downstream transects between source and mouth. Calculated pCO2 values at the source were 21 400 ± 2400 µatm. The pCO2 rapidly decreased in the river water and dropped to an average of 1240 ± 330 µatm near the mouth. About 90% of this decrease occurred within the first 6 km of the river. The river was supersaturated with respect to CO2 over its entire course and must have acted as a continuous year-round CO2 source to the atmosphere. The average CO2 flux from the karst river was estimated with 450 mmol m−2 day−1 with higher fluxes up to 5680 mmol m−2 day−1 at the source. At the source, δ13CDIC values showed no seasonal variations with an average of −14.2 ± 0.2‰. This indicated that groundwater retained high pCO2 mainly from soil CO2. The contribution of soil CO2 to Dissolved Inorganic Carbon was estimated at 65% to 72%. The downstream CO2 loss caused a positive shift in δ13CDIC values of 2‰ between source and mouth because of the preferential loss of the 12C isotope during degassing. Considering the findings of this study and the fact that Carbonate lithology covers a significant part of the earth's surface, CO2 evasion from karst regions might contribute notably to the annual Carbon dioxide release from global freshwater systems. Copyright © 2015 John Wiley & Sons, Ltd.

  • Sampling and analytical methods of stable isotopes and Dissolved Inorganic Carbon from CO2 injection sites
    2010
    Co-Authors: Robert Van Geldern, Anssi Myrttinen, Veith Becker, Johannes A. C. Barth
    Abstract:

    The isotopic composition (δC) of Dissolved Inorganic Carbon (DIC), in combination with DIC concentration measurements, can be used to quantify geochemical trapping of CO2 in water. This is of great importance in monitoring the fate of CO2 in the subsurface in CO2 injection projects. When CO2 mixes with water, a shift in the δC values, as well as an increase in DIC concentrations is observed in the CO2-H2O system. However, when using standard on-site titration methods, it is often challenging to determining accurate in-situ DIC concentrations. This may be due to CO2 degassing and CO2-exchange between the sample and the atmosphere during titration, causing a change in the pH value or due to other unfavourable conditions such as turbid water samples or limited availability of fluid samples.

Brian Colman - One of the best experts on this subject based on the ideXlab platform.

  • Regulation of Dissolved Inorganic Carbon transport in green algae
    Canadian Journal of Botany, 1998
    Co-Authors: Yusuke Matsuda, Gale G. Bozzo, Brian Colman
    Abstract:

    The regulation of the expression of the Inorganic Carbon concentrating mechanism (CCM) in aquatic photoautotrophs, particularly green algae, has been thought to require light and active photosynthesis. Recent studies, however, have indicated that there may be a light-independent pathway of signal transduction in green algae that may regulate the expression of CCMs in response to changes in ambient Dissolved Inorganic Carbon (DIC) concentration. In the green alga, Chlorella ellipsoidea, changes in the rate of transport of both CO2 and HCO3- were shown to occur in response to the CO2 concentration in the bulk medium, independent of pH, whereas other Inorganic Carbon species, which might induce or repress DIC transport expression, were shown to change markedly with the pH of the medium. Furthermore, neither changes in the CO2 concentration around ribulose bisphosphate carboxylase-oxygenase (Rubisco) nor light were shown to be critical factors in regulating CCM expression in this alga. CO2-insensitive mutants...

  • Quantification of the Contribution of CO2, HCO3-, and External Carbonic Anhydrase to Photosynthesis at Low Dissolved Inorganic Carbon in Chlorella saccharophila.
    Plant physiology, 1995
    Co-Authors: T. G. Williams, Brian Colman
    Abstract:

    An equation has been developed incorporating whole-cell rate constants for CO2 and HCO3- that describes accurately photosynthesis (Phs) in suspensions of unicellular algae at low Dissolved Inorganic Carbon. At pH 8.0 the concentration of CO2 available to the algal cells depends on the rate of supply from, and the loss to, HCO3- and the rate of use by the cells. At elevated cell densities (>30 mg chlorophyll [Chl] L-1), at which CO2 use by the cells is high, the slope of a graph of absolute Phs versus Chl concentration approaches the rate of Phs on a milligram of Chl basis because of HCO3- use alone. The slope of a graph of Phs versus HCO3- will be the rate constant for HCO3-, and for Chlorella saccharophila it was 0.16 L mg-1 Chl h-1. The difference between the constants for Dissolved Inorganic Carbon (measured in cells with external Carbonic anhydrase) and HCO3-1 is the constant for CO2, which was 26 L mg-1 Chl h-1. This difference causes the half-saturation constant for Phs to increase 5- to 6-fold at high cell densities. The increase in CO2 use as a result of external Carbonic anhydrase is described mathematically as a function of cell density.