scholarly journals Isotopic Analysis and Cycling of Dissolved Inorganic Carbon at Lake Biwa, Central Japan

Radiocarbon ◽  
1997 ◽  
Vol 40 (2) ◽  
pp. 933-944 ◽  
Author(s):  
Toshio Nakamura ◽  
Sadao Kojima ◽  
Tomoko Ohta ◽  
Hirotaka Oda ◽  
Akiko Ikeda ◽  
...  
Keyword(s):  
Inorganic Carbon ◽  
Lake Biwa ◽  
Dissolved Inorganic Carbon ◽  
Seasonal Pattern ◽  
Vertical Mixing ◽  
Isotopic Analysis ◽  
Early Spring ◽  
Central Japan ◽  
Depth Profiles ◽  
Carbon Isotopic

This paper reports on concentrations and carbon isotopic results of dissolved inorganic carbon (DIC) in water samples collected at four locations and from several depths in Lake Biwa, central Japan, covering every season of the year, starting in the spring of 1995. Depth profiles of DIC concentration and DIC δ13C showed a strong seasonal pattern, as a result of vertical mixing of the lake water in winter and early spring, or lack of mixing in the other seasons. No seasonal change in DIC ∆14C depth profiles was recognizable, mainly owing to the wide scatter of DIC ∆14C. Values typically ranged from 0.47 to 0.65 mmol kg-1 for DIC concentration, and from -4 to -8‰ and from +10 to +80‰ for DIC ∆13C and DIC ∆14C, respectively, for the Lake Biwa water.

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

Radiocarbon ◽  
1992 ◽  
Vol 34 (3) ◽  
pp. 636-645 ◽  
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.

scholarly journals Fluxes of carbon and nutrients to the Iceland Sea surface layer and inferred primary productivity and stoichiometry

2014 ◽  
Vol 11 (11) ◽  
pp. 15399-15433
Author(s):  
E. Jeansson ◽  
R. G. J. Bellerby ◽  
I. Skjelvan ◽  
H. Frigstad ◽  
S. R. Ólafsdóttir ◽  
...  
Keyword(s):  
Surface Layer ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Vertical Mixing ◽  
Sea Surface ◽  
Net Community Production ◽  
Horizontal Advection ◽  
Vertical Fluxes ◽  
Biological Uptake ◽  
Community Production

Abstract. Fluxes of carbon and nutrients to the upper 100 m of the Iceland Sea are evaluated. The study utilises hydro-chemical data from the Iceland Sea time-series station (68.00° N, 12.67° W), for the years between 1993 and 2006. By comparing data of dissolved inorganic carbon (DIC) and nutrients in the surface layer (upper 100 m), and a sub-surface layer (100–200 m), we calculate monthly deficits in the surface, and use these to deduce the surface layer fluxes that affect the deficits: vertical mixing, horizontal advection, air–sea exchange, and biological activity. The deficits show a clear seasonality with a minimum in winter, when the mixed layer is at the deepest, and a maximum in early autumn, when biological uptake has removed much of the nutrients. The annual vertical fluxes of DIC and nitrate amounts to 1.7 ± 0.3 and 0.23 ± 0.07 mol m−2 yr−1, respectively, and the annual air–sea uptake of atmospheric CO2 is 4.4 ± 1.1 mol m−2 yr−1. The biologically driven changes in DIC during the year relates to net community production (NCP), and the net annual NCP corresponds to export production, and is here calculated to 6.1 ± 0.9 mol C m−2 yr−1. The typical, median C : N ratio during the period of net community uptake is 11, and thus clearly higher than Redfield, but is varying during the season.

scholarly journals Aragonite saturation states and pH in western Norwegian fjords: seasonal cycles and controlling factors, 2005–2009

Ocean Science ◽  
2016 ◽  
Vol 12 (4) ◽  
pp. 937-951 ◽  
Author(s):  
Abdirahman M. Omar ◽  
Ingunn Skjelvan ◽  
Svein Rune Erga ◽  
Are Olsen
Keyword(s):  
Coastal Water ◽  
Spring Bloom ◽  
Dissolved Inorganic Carbon ◽  
Vertical Mixing ◽  
Late Summer ◽  
Early Spring ◽  
Saturation State ◽  
Aragonite Saturation ◽  
Anthropogenic Carbon ◽  
Carbon Dioxide Co2

Abstract. The uptake of anthropogenic carbon dioxide (CO2) by the ocean leads to a process known as ocean acidification (OA), which lowers the aragonite saturation state (ΩAr) and pH, and this is poorly documented in coastal environments including fjords due to lack of appropriate observations.Here we use weekly underway data from the Voluntary Observing Ships (VOS) program covering the period 2005–2009 combined with data from research cruises to estimate ΩAr and pH values in several adjacent western Norwegian fjords, and to evaluate how seawater CO2 chemistry drives their variations in response to physical and biological factors.The OA parameters in the surface waters of the fjords are subject to strong seasonal and spatially coherent variations. These changes are governed by the seasonal changes in temperature, salinity, formation and decay of organic matter, and vertical mixing with deeper, carbon-rich coastal water. Annual mean pH and ΩAr values were 8.13 and 2.21, respectively. The former varies from minimum values ( ≈  8.05) in late December – early January to maximum values of around 8.2 during early spring (March–April) as a consequence of the phytoplankton spring bloom, which reduces dissolved inorganic carbon (DIC). In the following months, pH decreases in response to warming. This thermodynamic decrease in pH is reinforced by the deepening of the mixed layer, which enables carbon-rich coastal water to reach the surface, and this trend continues until the low winter values of pH are reached again. ΩAr, on the other hand, reaches its seasonal maximum (> 2.5) in mid- to late summer (July–September), when the spring bloom is over and pH is decreasing. The lowest ΩAr values ( ≈  1.3–1.6) occur during winter (January–March), when both pH and sea surface temperature (SST) are low and DIC is its highest. Consequently, seasonal ΩAr variations align with those of SST and salinity normalized DIC (nDIC).We demonstrate that underway measurements of fugacity of CO2 in seawater (fCO2) and SST from VOS lines combined with high frequency observations of the complete carbonate system at strategically placed fixed stations provide an approach to interpolate OA parameters over large areas in the fjords of western Norway.

Long-term variation in dissolved inorganic carbon and ocean acidification indices in the Northwest Pacific from 1993 to 2018: A study of a biogeochemical model with an operational ocean model product and observational evidence

2021 ◽  
Author(s):  
Miho Ishizu ◽  
Yasumasa Miyazawa ◽  
Xinyu Guo
Keyword(s):  
Ocean Acidification ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Kuroshio Extension ◽  
Vertical Mixing ◽  
Ocean Model ◽  
Biogeochemical Model ◽  
Northwest Pacific ◽  
Subarctic Region ◽  
Surface Ocean

Abstract The multi-decadal variation in ocean acidification indices in the Northwest Pacific was examined using a biogeochemical model with an operational ocean model product for the period 1993–2018. We found that ocean acidification varied regionally in the Northwest Pacific. The surface ocean (above 100 m depth) underwent acidification that progressed more quickly in the subtropical region and the Kuroshio extension than in the subarctic region due to vertical mixing of the dissolved inorganic carbon (DIC) supply exceeding DIC release by air–sea exchange. Below 100 m depth, acidification and alkalinization occurred in the subtropical and subarctic regions, respectively. We attribute these regional differences in acidification and alkalinization to spatially variable biological processes in the upper layer and physical redistribution of DIC, both horizontally and vertically.

The interplay of glacial/interglacial climate-CO2 and productivity effects on coccolith calcification and vital effects across the MIS 12 to MIS 9 in the western tropical Atlantic

2020 ◽  
Author(s):  
Alba González-Lanchas ◽  
Heather M. Stoll ◽  
José-Abel Flores ◽  
Francisco J. Sierro ◽  
Ivan Hernandez-Almeida ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Isotopic Fractionation ◽  
Tropical Atlantic ◽  
Physiological Mechanisms ◽  
Carbon Isotopic ◽  
Acquisition Strategies ◽  
Climatic Period ◽  
Vital Effects

<p>Coccolithophores play an important dual role in ocean biogeochemistry: they use dissolved inorganic carbon (DIC) in the surface for both photosynthesis and coccolith calcification. Stable isotopes in coccoliths are the result of various effects, including different vital effects, allowing hypotheses about the varying active carbon acquisition strategies in response to changing environmental conditions. Understanding the physiological mechanisms that cause these changes remains challenging.</p><p>The MIS 12 to MIS 9 interval is a crucial climatic period encompassing changing glacial-interglacial cyclicity and pronounced variations in atmospheric CO<sub>2</sub> concentration. Different paleorecords indicate that coccoliths were an important component of the carbonate fraction during this interval, with the outstanding worldwide dominance of the highly calcified coccolithophore species <em>Gephyrocapsa caribbeanica</em>.</p><p>The carbon isotopic fractionation during photosynthesis (εp) in alkenones, biomarkers produced by coccolithophores, is a proxy to reconstruct past aqueous CO<sub>2</sub> concentration. Here we present a new εp reconstruction spanning this glacial/interglacial interval (460 to 330 kyr) at ODP Site 925 in the western tropical Atlantic. We aim to evaluate the interplay of CO<sub>2 </sub>and productivity effects on coccolith calcification and stable isotopes (δ<sup>18</sup>O and δ<sup>13</sup>C) in coccolith calcite integrating these data with the size and thickness of coccolith platelets and the geochemical Sr/Ca record.</p><p>The comparison of mean coccolith size with coeval samples from the deeper ODP Site 929 allows the evaluation of the degree of nannofossil dissolution across the interval.</p>

scholarly journals Differences in metabolic rate between two Atlantic cod (Gadus morhua) populations estimated with carbon isotopic composition in otoliths

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0248711
Author(s):  
Szymon Smoliński ◽  
Côme Denechaud ◽  
Gotje von Leesen ◽  
Audrey J. Geffen ◽  
Peter Grønkjær ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Gadus Morhua ◽  
Inorganic Carbon ◽  
Atlantic Cod ◽  
Dissolved Inorganic Carbon ◽  
Physiological State ◽  
Carbon Isotopic Composition ◽  
Physiological Basis ◽  
Carbon Isotopic ◽  
Growth Increments

The isotopic composition of inorganic carbon in otoliths (δ13Coto) can be a useful tracer of metabolic rates and a method to study ecophysiology in wild fish. We evaluated environmental and physiological sources of δ13Coto variation in Icelandic and Northeast Arctic (NEA) cod (Gadus morhua) over the years 1914–2013. Individual annual growth increments of otoliths formed at age 3 and 8 were micromilled and measured by isotope-ratio mass spectrometry. Simultaneously, all annual increment widths of the otoliths were measured providing a proxy of fish somatic growth. We hypothesized that changes in the physiological state of the organism, reflected by the isotopic composition of otoliths, can affect the growth rate. Using univariate and multivariate mixed-effects models we estimated conditional correlations between carbon isotopic composition and growth of fish at different levels (within individuals, between individuals, and between years), controlling for intrinsic and extrinsic effects on both otolith measurements. δ13Coto was correlated with growth within individuals and between years, which was attributed to the intrinsic effects (fish age or total length). There was no significant correlation between δ13Coto and growth between individuals, which suggests that caution is needed when interpreting δ13Coto signals. We found a significant decrease in δ13Coto through the century which was explained by the oceanic Suess effect-admixture of isotopically light carbon from fossil fuel. We calculated the proportion of the respired carbon in otolith carbonate (Cresp) using carbon isotopic composition in diet and dissolved inorganic carbon of the seawater. This approach allowed us to correct the values for each stock in relation to these two environmental baselines. Cresp was on average 0.275 and 0.295 in Icelandic and NEA stock, respectively. Our results provide an insight into the physiological basis for differences in growth characteristics between these two cod stocks, and how that may vary over time.

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