Determining the stable isotope ratio of total dissolved inorganic carbon in lake water by GC/C/IIRMS

Miyajima, Toshihiro; Miyajima, Yoshihiro; Hanba, Yuko T.; Yoshii, Kazumichi; Koitabashi, Tadatoshi; Wada, Eitaro

doi:10.4319/lo.1995.40.5.0994

Cited by 118 publications

(79 citation statements)

References 5 publications

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“…The isotopic value of the Na 2 CO 3 standard was À4.5 ± 0.2‰. Finally, to correct for the partitioning of CO 2 between the headspace and water phase in the samples and to calculate the d 13 C of the total DIC, the isotopic fractionation of CO 2 at the water-air interface as a function of lab temperature of Miyajima et al (1995) was applied. TA was analysed on filtered samples by automated electrotitration on 50 mL filtered samples with 0.1 N HCl as the titrant.…”

Section: Laboratory Analysismentioning

confidence: 99%

Carbon dioxide degassing at the groundwater-stream-atmosphere interface: isotopic equilibration and hydrological mass balance in a sandy watershed

Deirmendjian

Abril

2018

Journal of Hydrology

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a b s t r a c tStreams and rivers emit significant amounts of CO 2 and constitute a preferential pathway of carbon transport from terrestrial ecosystems to the atmosphere. However, the estimation of CO 2 degassing based on the water-air CO 2 gradient, gas transfer velocity and stream surface area is subject to large uncertainties. Furthermore, the stable isotope signature of dissolved inorganic carbon (d 13 C-DIC) in streams is strongly impacted by gas exchange, which makes it a useful tracer of CO 2 degassing under specific conditions. For this study, we characterized the annual transfers of dissolved inorganic carbon (DIC) along the groundwater-stream-river continuum based on DIC concentrations, stable isotope composition and measurements of stream discharges. We selected a homogeneous, forested and sandy lowland watershed as a study site, where the hydrology occurs almost exclusively through drainage of shallow groundwater (no surface runoff). We observed the first general spatial pattern of decreases in pCO 2 and DIC and an increase in d 13 C-DIC from groundwater to stream orders 1 and 2, which was due to the experimentally verified faster degassing of groundwater 12 C-DIC compared to 13 C-DIC. This downstream enrichment in 13 C-DIC could be modelled by simply considering the isotopic equilibration of groundwater-derived DIC with the atmosphere during CO 2 degassing. A second spatial pattern occurred between stream orders 2 and 4, consisting of an increase in the proportion of carbonate alkalinity to the DIC accompanied by the enrichment of 13 C in the stream DIC, which was due to the occurrence of carbonate rock weathering downstream. We could separate the contribution of these two processes (gas exchange and carbonate weathering) in the stable isotope budget of the river network. Thereafter, we built a hydrological mass balance based on drainages and the relative contribution of groundwater in streams of increasing order. After combining with the dissolved CO 2 concentrations, we quantified CO 2 degassing for each stream order for the whole watershed. Approximately 75% of the total CO 2 degassing from the watershed occurred in first-and second-order streams. Furthermore, from stream order 2-4, our CO 2 degassing fluxes compared well with those based on stream hydraulic geometry, water pCO 2 , gas transfer velocity, and stream surface area. In first-order streams, however, our approach showed CO 2 fluxes that were twice as large, suggesting that a fraction of degassing occurred as hotspots in the vicinity of groundwater resurgence and was missed by conventional stream sampling.

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Section: Laboratory Analysismentioning

confidence: 99%

Carbon dioxide degassing at the groundwater-stream-atmosphere interface: isotopic equilibration and hydrological mass balance in a sandy watershed

Deirmendjian

Abril

2018

Journal of Hydrology

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“…The oxygen isotopic compositions of hydrothermally altered mud were determined as previously described (Miyoshi, 2013). The concentration and isotopic composition of dissolved inorganic carbon (DIC) was determined as previously described (Miyajima et al, 1995;Toki et al, 2004;Noguchi et al, 2013). Details are provided in Supplementary Information Materials and methods.…”

Section: Geochemical Analysesmentioning

confidence: 99%

Defining boundaries for the distribution of microbial communities beneath the sediment-buried, hydrothermally active seafloor

et al. 2016

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Subseafloor microbes beneath active hydrothermal vents are thought to live near the upper temperature limit for life on Earth. We drilled and cored the Iheya North hydrothermal field in the MidOkinawa Trough, and examined the phylogenetic compositions and the products of metabolic functions of sub-vent microbial communities. We detected microbial cells, metabolic activities and molecular signatures only in the shallow sediments down to 15.8 m below the seafloor at a moderately distant drilling site from the active hydrothermal vents (450 m). At the drilling site, the profiles of methane and sulfate concentrations and the δ 13 C and δD isotopic compositions of methane suggested the laterally flowing hydrothermal fluids and the in situ microbial anaerobic methane oxidation. In situ measurements during the drilling constrain the current bottom temperature of the microbially habitable zone to~45°C. However, in the past, higher temperatures of 106-198°C were possible at the depth, as estimated from geochemical thermometry on hydrothermally altered clay minerals. The 16S rRNA gene phylotypes found in the deepest habitable zone are related to those of thermophiles, although sequences typical of known hyperthermophilic microbes were absent from the entire core. Overall our results shed new light on the distribution and composition of the boundary microbial community close to the high-temperature limit for habitability in the subseafloor environment of a hydrothermal field.

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“…The same system was used to measure the stable carbon isotope ratio ( 13 C/ 12 C) of methane when the pyrolysis furnace and the ThermoQuest Delta plus XP were replaced with a combustion furnace (ceramic tube packed with CuO, NiO, and Pt wires) and a Finnigan MAT 252 IRMS (Finnigan MAT, Bremen, Germany). The 13 C/ 12 C of total dissolved inorganic carbon (SCO 2 ) in groundwater, mainly bicarbonate, was analyzed according to an earlier described method (Miyajima et al, 1995). Groundwater samples for analysis of 13 C/ 12 C of SCO 2 were collected into an autoclaved serum bottles (inner volume, 68.6 ml), fixed with 0.5 ml of saturated HgCl 2 solution, and sealed with a sterile butyl rubber stoppers and aluminum crimps with no air bubbles.…”

Section: Analysis Of Stable Isotopic Ratiosmentioning

confidence: 99%

Microbial methane production in deep aquifer associated with the accretionary prism in Southwest Japan

et al. 2009

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To identify the methanogenic pathways present in a deep aquifer associated with an accretionary prism in Southwest Japan, a series of geochemical and microbiological studies of natural gas and groundwater derived from a deep aquifer were performed. Stable carbon isotopic analysis of methane in the natural gas and dissolved inorganic carbon (mainly bicarbonate) in groundwater suggested that the methane was derived from both thermogenic and biogenic processes. Archaeal 16S rRNA gene analysis revealed the dominance of H 2 -using methanogens in the groundwater. Furthermore, the high potential of methane production by H 2 -using methanogens was shown in enrichments using groundwater amended with H 2 and CO 2 . Bacterial 16S rRNA gene analysis showed that fermentative bacteria inhabited the deep aquifer. Anaerobic incubations using groundwater amended with organic substrates and bromoethanesulfonate (a methanogen inhibitor) suggested a high potential of H 2 and CO 2 generation by fermentative bacteria. To confirm whether or not methane is produced by a syntrophic consortium of H 2 -producing fermentative bacteria and H 2 -using methanogens, anaerobic incubations using the groundwater amended with organic substrates were performed. Consequently, H 2 accumulation and rapid methane production were observed in these enrichments incubated at 55 and 65 1C. Thus, our results suggested that past and ongoing syntrophic biodegradation of organic compounds by H 2 -producing fermentative bacteria and H 2 -using methanogens, as well as a thermogenic reaction, contributes to the significant methane reserves in the deep aquifer associated with the accretionary prism in Southwest Japan.

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Determining the stable isotope ratio of total dissolved inorganic carbon in lake water by GC/C/IIRMS

Cited by 118 publications

References 5 publications

Carbon dioxide degassing at the groundwater-stream-atmosphere interface: isotopic equilibration and hydrological mass balance in a sandy watershed

Carbon dioxide degassing at the groundwater-stream-atmosphere interface: isotopic equilibration and hydrological mass balance in a sandy watershed

Defining boundaries for the distribution of microbial communities beneath the sediment-buried, hydrothermally active seafloor

Microbial methane production in deep aquifer associated with the accretionary prism in Southwest Japan

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