Natural C-14 provides new data for stream food-web studies: a comparison with C-13 in multiple stream habitats

2012 ◽  
Vol 63 (3) ◽  
pp. 210 ◽  
Author(s):  
Naoto F. Ishikawa ◽  
Masao Uchida ◽  
Yasuyuki Shibata ◽  
Ichiro Tayasu
Keyword(s):  
Food Web ◽  
Inorganic Carbon ◽  
Photosynthetic Activity ◽  
Dissolved Inorganic Carbon ◽  
Carbon Sources ◽  
Δ13c Values ◽  
Web Studies ◽  
The Difference

In stream food-web analysis, the contributions of carbon from periphyton (an autochthonous source) and terrestrial litter (an allochthonous source) are estimated by isotopic difference. We hypothesised that periphyton δ13C varies among stream habitats, whereas Δ14C does not because Δ14C is corrected with δ13C, by definition. To test this hypothesis, we compared the variability of δ13C and Δ14C of periphyton and dissolved inorganic carbon (DIC) in four habitats (open v. shaded, riffle v. pool) within a limestone-based upland stream in Japan. Periphyton δ13C values (from –31.9‰ to –16.3‰) were significantly different among the habitats whereas the Δ14C values (from –379‰ to –141‰) were not. Periphyton δ13C values depended on both algal photosynthetic activity and δ13C of the DIC, whereas periphyton Δ14C depended only on DIC Δ14C. The δ13C and Δ14C values of litter were constant. Thus, the difference between the periphyton and litter δ13C values (Δδ13C) varied among habitats, but their Δ14C differences (ΔΔ14C) did not. Our results indicate that Δ14C is spatially stable among stream habitats and that Δ14C measurements can be used to precisely determine carbon sources for stream food-web analysis within individual reaches.

Food web reliance on allochthonous carbon in two high mountain lakes with contrasting catchments: a stable isotope approach

2005 ◽  
Vol 62 (11) ◽  
pp. 2640-2648 ◽  
Author(s):  
Elvira Pulido-Villena ◽  
Isabel Reche ◽  
Rafael Morales-Baquero
Keyword(s):  
Organic Matter ◽  
Food Web ◽  
Particulate Organic Matter ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Isotopic Signature ◽  
Mountain Lakes ◽  
High Mountain ◽  
Terrestrial Carbon ◽  
High Mountain Lakes

The carbon isotopic signature (δ13C) of dissolved inorganic carbon and food web components was examined in two high mountain lakes. Río Seco Lake is partially surrounded by alpine meadows and has temporal inlets, whereas La Caldera Lake is located on rocky terrain and does not receive inputs from runoff. We assessed whether these contrasting catchments involve differences in the isotopic signature of the food web components and then in the reliance on terrestrial carbon. The δ13C of dissolved inorganic carbon was not significantly different between lakes and reflected an atmospheric gas exchange origin. Unexpectedly, bulk particulate organic matter showed enriched δ13C values in both lakes, suggesting a terrestrial vegetation influence. Bulk particulate organic matter was exploited mostly by the cladoceran Daphnia pulicaria, whereas the copepod Mixodiaptomus laciniatus was 13C depleted relative to particulate organic matter, indicating a selective feeding on an isotopically lighter source, likely phytoplankton. The results obtained show that, despite contrasting catchments, the food web of both lakes might be partially supported by terrestrial carbon for which utilization is species specific.

scholarly journals Comparison of 14C Collected by Precipitation and Gas-Strip Methods for Dating Groundwater

Radiocarbon ◽  
2016 ◽  
Vol 58 (3) ◽  
pp. 491-503 ◽  
Author(s):  
Kotaro Nakata ◽  
Takuma Hasegawa ◽  
Teruki Iwatsuki ◽  
Toshihiro Kato
Keyword(s):  
Residence Time ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Precipitation Method ◽  
Strip Method ◽  
Naoh Solution ◽  
C Value ◽  
The Difference ◽  
Predicted Values

AbstractDissolved inorganic carbon (DIC) in groundwater is used to estimate the residence time based on radiocarbon concentration. DIC is usually extracted by a gas-strip or precipitation (SrCO3 or BaCO3) method. In this study, the gas-strip and precipitation methods of DIC were applied to both artificially prepared NaHCO3 solutions and natural groundwater to estimate the certainty of the two methods for 14C dating. 14C values obtained by the gas-strip method for NaHCO3 solutions with distinct salinity, DIC, and 14C concentrations were close to the theoretically predicted 14C value based on the 14C value of NaHCO3 powder. Conversely, the 14C value obtained by the precipitation method always showed higher values than the predicted values. The difference in 14C value between the gas-strip and precipitation methods was assumed to be caused by the contamination of modern carbon in the NaOH solution used in the precipitation method. The contamination of modern carbon derived from the NaOH solution during precipitation was found to range from less than 1 mg/L to about 1 mg/L. The applicability of the precipitation method for groundwater should be considered carefully according to the DIC, 14C concentration of groundwater, and purpose of the study being conducted.

scholarly journals Dynamics of dissolved inorganic carbon in the Yenisey gulf during open water period

2019 ◽  
Vol 59 (5) ◽  
pp. 701-713
Author(s):  
P. N. Makkaveev ◽  
Yu. R. Nalbandov ◽  
A. A. Polukhin ◽  
S. A. Schuka
Keyword(s):  
Suspended Matter ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Open Water ◽  
Bottom Layer ◽  
Sediment Layer ◽  
Almost Everywhere ◽  
Mineral Suspension ◽  
The Difference ◽  
The Many

On the materials of several SIO RAS cruises and archival hydrological and hydrochemical data, the dynamics of dissolved inorganic carbon in the Yenisey Gulf was investigated. There are 3 main areas, where mass sedimentation of suspended matter and oxidation of organic matter (OM) in the upper sediment layer takes place. The first region of oxidation of OM was south of 72 N, its existence is associated with mass sedimentation of dissolved and suspended matter on the geochemical barrier. Two other areas of decomposition of the OM (elevated dCtot) are located downstream (between 73 and 74 and north of 75 N) and most likely originated at the orographic barrier, where the change in the dynamic characteristics of the riverine flow and the topography of the bay bottom creates conditions for sedimentation. Comparison of the difference in the observed Ctot value with the AOU value showed that in 1993, the change in the Ctot content was provided by the oxidation processes of OM. In 2011, carbon emission into water was most likely associated with the transformation of mineral suspension and/or carbon exchange in bottom water with bottom sediments. In 2016, a decrease in the Ctot content was observed almost everywhere in bottom layer. It is most realistic to assume that such a distribution is associated with carbon sorption on suspensions. Despite the many similar features of the distribution of hydrochemical characteristics in the bay, the change in the content of dissolved inorganic carbon in the investigated area has differed greatly in different years. In our opinion, the reason for the fact is the variability of the discharge of the Yenisey River in different years.

A physiological evaluation of carbon sources for calcification in the octocoral Leptogorgia virgulata (Lamarck).

1997 ◽  
Vol 200 (20) ◽  
pp. 2653-2662
Author(s):  
J M Lucas ◽  
L W Knapp
Keyword(s):  
Calcium Carbonate ◽  
Carbonic Anhydrase ◽  
Inorganic Carbon ◽  
Sea Water ◽  
Dissolved Inorganic Carbon ◽  
Carbon Sources ◽  
Iodoacetic Acid ◽  
Transport Systems ◽  
Disulfonic Acid ◽  
Leptogorgia Virgulata

The union of calcium cations with carbonate anions to form calcium carbonate (CaCO3) is a fundamentally important physiological process of many marine invertebrates, in particular the corals. In an effort to understand the sources and processes of carbon uptake and subsequent deposition as calcium carbonate, a series of studies of the incorporation of 14C-labeled compounds into spicules was undertaken using the soft coral Leptogorgia virgulata. It has been surmised for some time that dissolved inorganic carbon in sea water is used in the biomineralization process. Furthermore, it was suspected that metabolically generated CO2 is also available for calcification. As a means of testing these possible sources of carbon in spicule calcification, key enzymes or transport systems in each pathway were inhibited. First, the enzyme carbonic anhydrase was specifically inhibited using acetazolamide. Second, the active transport of bicarbonate was inhibited using DIDS (4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid). Third, CO2 generation resulting from glycolysis and the citric acid cycle was arrested using iodoacetic acid, which interferes specifically with the enzyme glyceraldehyde-3-phosphate dehydrogenase. The results indicate that dissolved CO2 is the largest source of carbon used in the formation of calcitic sclerites, followed by HCO3- from dissolved inorganic carbon. In L. virgulata, the dissolved inorganic carbon is responsible for approximately 67% of the carbon in the sclerites. The other 33% comes from CO2 generated by glycolysis. Two important conclusions can be drawn from this work. First, carbon for spiculogenesis comes not only from dissolved inorganic carbon in the environment but also from metabolically produced carbon dioxide. While the latter has been theorized, it has never before been demonstrated in octocorals. Second, regardless of the carbon source, the enzyme carbonic anhydrase plays a pivotal role in the physiology of spicule formation in Leptogorgia virgulata.

scholarly journals Carbon isotopes of dissolved inorganic carbon reflect utilization of different carbon sources by microbial communities in two limestone aquifer assemblages

2016 ◽  
Author(s):  
Martin E. Nowak ◽  
Valérie F. Schwab ◽  
Cassandre S. Lazar ◽  
Thomas Behrendt ◽  
Bernd Kohlhepp ◽  
...  
Keyword(s):  
Organic Matter ◽  
Microbial Communities ◽  
Carbon Isotopes ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Carbon Sources ◽  
Oxygen Depletion ◽  
C Isotopes ◽  
Abiotic Controls ◽  
Upper Aquifer

Abstract. Isotopes of dissolved inorganic carbon (DIC) are used to indicate both transit times and biogeochemical evolution of groundwaters. These signals can be complicated in carbonate aquifers, as both abiotic (i.e. carbonate equilibria) and biotic factors influence δ13C and 14C of DIC. We applied a novel graphical method for tracking changes in δ13C and 14C of DIC in two distinct aquifer complexes identified in the Hainich Critical Zone Exploratory (CZE), a platform to study how water transport links surface and shallow groundwaters in limestone and marlstone rocks in central Germany. For more quantitative estimates of contributions of different biotic and abiotic carbon sources to the DIC pool, we used the geochemical modelling program NETPATH, which accounts for changes in dissolved ions in addition to C isotopes. Although water residence times in the Hainich CZE aquifers based on hydrogeology are relatively short (years or less), DIC isotopes in the shallow, mostly anoxic, aquifer assemblage (HTU) were depleted in 14C compared to a deeper, oxic, aquifer complex (HTL). Carbon isotopes and chemical changes in the deeper HTL wells could be explained by interaction of recharge waters equilibrated with post-bomb 14C sources with carbonates. However, oxygen depletion and δ13C and 14C values of DIC below those expected from the processes of carbonate equilibrium alone indicate dramatically different biogeochemical evolution of waters in the upper aquifer assemblage (HTU wells). Changes of 14C and 13C in the upper aquifer complexes result from a number of biotic and abiotic processes, including oxidation of 14C depleted OM derived from recycled microbial carbon and sedimentary organic matter as well as water rock interactions. The microbial pathways inferred from DIC isotope shifts and changes in water chemistry in the HTU wells were supported by comparison with in situ microbial community structure based on 16S rRNA analyses. Our findings demonstrate the large variation in the importance of biotic as well as abiotic controls on 13C and 14C of DIC in closely related aquifer assemblages. Further, they support the importance of subsurface derived carbon sources like DIC for chemolithoautotrophic microorganisms as well as rock-derived organic matter for supporting heterotrophic groundwater microbial communities and indicate that even shallow aquifers have microbial communities that use a variety of subsurface derived carbon sources.

scholarly journals Mechanism of O and C isotope fractionation in magnesian calcite skeletons of <i>Octocorallia</i> corals and an implication on their calcification response to ocean acidification

2015 ◽  
Vol 12 (1) ◽  
pp. 389-412 ◽  
Author(s):  
T. Yoshimura ◽  
A. Suzuki ◽  
N. Iwasaki
Keyword(s):  
Ocean Acidification ◽  
Isotope Fractionation ◽  
Inorganic Carbon ◽  
Environmental Changes ◽  
Dissolved Inorganic Carbon ◽  
Carbon Sources ◽  
Ambient Seawater ◽  
Large Variability ◽  
Coral Skeletons ◽  
Δ18o And Δ13c

Abstract. Coral calcification is strongly dependent on both the pH and the dissolved inorganic carbon (DIC) of the calcifying fluid. Skeletal oxygen and carbon isotope fractionation of high-Mg calcite skeletons of \\textit{Octocorallia} corals directly record the biological manipulation on sources of DIC in response to environmental changes. The coral skeletons were enriched in light isotopes (16O and 12C) relative to the expected values based on habitat environmental parameters and Mg/Ca of the skeletons. The differences between the expected and observed values ranged from −4.66 to −1.53 for δ18O and from −7.34 to −1.75 for δ13C. The large variability cannot be explained by the ambient environment, the contribution of metabolic carbon, or the precipitation rate of the skeleton. Therefore, the most plausible explanation for the observed O and C isotope differences in high-Mg calcite coral skeletons is the existence of two carbon sources, aqueous carbon dioxide in the calcifying fluid and dissolved inorganic carbon in seawater. Positive correlations of B/Ca with δ18O and δ13C suggest that skeletal isotopic compositions are enriched in light isotopes when conditions are less alkaline. Therefore, the relative contribution of isotopically heavy DIC from seawater through the skeleton and pericellular channels decreases under the reduced pH of the extracytoplasmic calcifying fluid. Our data suggest an even stronger biological effect under lower pH. Skeletal δ18O and δ13C values record the response of the sources of DIC in the coral calcifying fluids to ambient seawater pH. These changes give insight into how ocean acidification impacts the physiological mechanisms as well as the pH offset between calcifying fluid and seawater in response to ocean acidification.

Sign in / Sign up

Export Citation Format

Share Document