Radiocarbon and stable carbon isotopic evidence for transport and transformation of dissolved organic carbon, dissolved inorganic carbon, and CH<sub>4</sub> in a northern Minnesota peatland

Chasar, L. S.; Chanton, Jeffrey P.; Glaser, Paul H.; Siegel, D. I.; Rivers, J. S.

doi:10.1029/1999gb001221

Cited by 193 publications

(213 citation statements)

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“…Interestingly, MES also contained other potential fermentation products, i.e., caproate, propionate, butyrate, isopropanol, and valerate, albeit at much lower concentrations than acetate. Such compounds are frequently observed in methanogenic lake sediments or flooded soils (Lovley and Klug, 1982;Phelps and Zeikus 1985;Chin and Conrad, 1995), but were not detected in OMB and OLI. There, acetate and other fermentation products seemed to play a comparatively minor role in the degradation of organic matter.…”

Section: Discussionmentioning

confidence: 99%

“…Later studies indicated that a decreasing pH resulted in decreasing acetate turnover and in the relative dominance of hydrogenotrophic methanogenesis (Kotsyurbenko et al, 2007), and that the type of vegetation, i.e., dominance of Sphagnum P. E. Galand et al: Carbon isotope fractionation in methanogenic peatlands over vascular plants, coincides with the occurrence of acetate accumulation . When acetoclastic methanogenesis operates, it seems to occur preferably in the upper peat layers, whereas the deep layers are dominated by CH 4 production from H 2 /CO 2 (Popp et al, 1999;Chasar et al, 2000;Kotsyurbenko et al, 2004). These observations indicate that the quality of the degradable organic substances may affect the path of CH 4 production .…”

Section: Introductionmentioning

confidence: 99%

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Stable carbon isotope fractionation during methanogenesis in three boreal peatland ecosystems

2010

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Abstract. The degradation of organic matter to CH 4 and CO 2 was investigated in three different boreal peatland systems in Finland, a mesotrophic fen (MES), an oligotrophic fen (OLI), and an ombrotrophic peat (OMB). MES had similar production rates of CO 2 and CH 4 , but the two nutrientpoor peatlands (OLI and OMB) produced in general more CO 2 than CH 4 . δ 13 C analysis of CH 4 and CO 2 in the presence and absence methyl fluoride (CH 3 F), an inhibitor of acetoclastic methanogenesis, showed that CH 4 was predominantly produced by hydrogenotrophic methanogenesis and that acetoclastic methanogenesis only played an important role in MES. These results, together with our observations concerning the collective inhibition of CH 4 and CO 2 production rates by CH 3 F, indicate that organic matter was degraded through different paths in the mesotrophic and the nutrient-poor peatlands. In the mesotrophic fen, the major process is canonical fermentation followed by acetoclastic and hydrogenotrophic methanogenesis, while in the nutrient-poor peat, organic matter was apparently degraded to a large extent by a different path which finally involved hydrogenotrophic methanogenesis. Our data suggest that degradation of organic substances in the oligotrophic environments was incomplete and involved the use of organic compounds as oxidants.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Stable carbon isotope fractionation during methanogenesis in three boreal peatland ecosystems

2010

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“…In general, such organic samples may be of low geochemical abundance, obtained in low yields after processing, require minimally invasive sampling to avoid methodological artifacts, or where increased sub-sampling (e.g., for additional complementary measurements or finer timeresolved analyses) is desired in systems otherwise constrained. Some possible examples include simplified porewater (Bauer et al 1995;Chasar et al 2000;Wassenaar et al 1990) analyses, observing rainwater DOC concentration and isotope ratio (Raymond 2005) evolve during a storm or brief shower, determining groundwater organic carbon fluxes and/or aquifer residence times (Burr et al 2001), monitoring the organic content of fluids within or pumped through organisms (Yahel et al 2003) isotopically, or sub-sampling vent waters to complement a suite of chemical analyses with Δ 14 C and δ 13 C measurements. Successful analyses of diluted seawater suggest that, with further testing, this reactor may also be useful in processing pure freshwater samples.…”

Section: Discussionmentioning

confidence: 99%

A low‐blank photochemical extraction system for concentration and isotopic analyses of marine dissolved organic carbon

Beaupré

Druffel

Griffin

2007

Limnology & Ocean Methods

128

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Dissolved organic carbon (DOC), operationally defined as the carbon contained in that fraction of organic matter in water which passes through a 0.2-1 μm filter, is the largest pool (ca. 0.6 × 10 18 g C) of organic matter in the oceans and is approximately equal in size to atmospheric CO 2 (Hedges 1992). Despite its abundance in the global carbon cycle and nearly a century of research, the majority (> 60% -80%) of DOC has remained molecularly uncharacterized (Hedges 1992) and its biogeochemical fluxes incompletely resolved. Global riverine input of ~0.2 Gt DOC per year (Meybeck 1982) is sufficient to support its radiocarbon ( 14 C) based oceanic residence time, yet composition (Meyers-Schulte and Hedges 1986; Opsahl and Benner 1997) and stable carbon ( 13 C) isotopic signature (Williams and Gordon 1970) measurements suggest the majority of marine DOC is autochthonous, ultimately originating from primary production in the euphotic zone. Furthermore, while the 4000 -6000 y 14 C ages reported for deep marine DOC suggest that a major proportion cycles on very long time scales and ages in situ during deep water transit (Bauer et al. 1992;Williams and Druffel 1987), the source of apparent chemical resilience and the removal processes necessary to produce these ages remain unknown. The published body of Δ 14 C values has been critical to understanding marine DOC biogeochemistry, yet it contains relatively few measurements because of methodological difficulties associated with low DOC concentrations, an overwhelming proportion of salts, and high blanks.The marine DOC ultraviolet (UV) extraction method (Armstrong et al. 1966;Williams 1968; Williams and Gordon 1970; Williams et al. 1969), and subsequent refinements (Bauer et al. 1998a;Druffel et al. 1989) that co-evolved with smaller sample size requirements of accelerator mass spectrometry (AMS) 14 C measurement, has been particularly wellsuited for isotopic analysis of marine DOC. It is amenable to batch reactors capable of oxidizing the large seawater aliquots required to collect enough DOC for isotopic analysis. It is a minimally invasive technique, involving only acidification and sparging of dissolved inorganic carbon (DIC) from filtered seawater prior to photochemical oxidation of DOC to CO 2 , thus minimizing the risk of contamination. Lastly, replicate analyses by Bauer et al. (1998a) demonstrated that good reproducibility (with single standard deviations of ± 1 μM and ± 3‰ to 6‰ for concentration and Δ 14 C measurements, respectively) accompanies low blanks (< 1.5 μM). Based on these techniques, a modified method for UV extraction of bulk marine nonvolatile DOC for isotopic analysis has been developed using simple, novel devices to decrease the analytical blank to ~0.2 μM, and reduce the AbstractWe report the development of a modified, low blank, ultraviolet oxidation and vacuum line system to convert marine dissolved organic carbon into carbon dioxide for concentration, Δ 14 C, and δ 13 C analyses. The system performs quantitatively and precisely with preserv...

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“…Dissolved organic carbon (DOC) and total dissolved nitrogen (TDN; as dissolved organic and inorganic N; DON, DIN) broadly influence terrestrial and aquatic ecosystem function and greenhouse gas emissions as they are biogeochemically cycled within soils (van Hees et al 2005, Weintraub andSchimel 2005), transported laterally to aquatic systems, and processed (Aufdenkampe et al 2011) and/or exported to coastal environments (Holmes et al 2011). Mineralization of DOC in soils and surface waters produces CO 2 and CH 4 that are emitted to the atmosphere (Chasar et al 2000, Bengtson and Bengtsson 2007, Drake et al 2015, and DON and DIN are essential nutrients that enhance primary production (Keuper et al 2012(Keuper et al , 2017 and decomposition (Mack et al 2004, Wickland et al 2012. Given the importance of DOC, DON and DIN to terrestrial and aquatic ecosystem function and gaseous and lateral fluxes, it is critical to quantify sources that become newly available as permafrost thaws.…”

Section: Introductionmentioning

confidence: 99%

Dissolved organic carbon and nitrogen release from boreal Holocene permafrost and seasonally frozen soils of Alaska

Wickland

Waldrop

Aiken

et al. 2018

Environ. Res. Lett.

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Permafrost (perennially frozen) soils store vast amounts of organic carbon (C) and nitrogen (N) that are vulnerable to mobilization as dissolved organic carbon (DOC) and dissolved organic and inorganic nitrogen (DON, DIN) upon thaw. Such releases will affect the biogeochemistry of permafrost regions, yet little is known about the chemical composition and source variability of active-layer (seasonally frozen) and permafrost soil DOC, DON and DIN. We quantified DOC, total dissolved N (TDN), DON, and DIN leachate yields from deep active-layer and near-surface boreal Holocene permafrost soils in interior Alaska varying in soil C and N content and radiocarbon age to determine potential release upon thaw. Soil cores were collected at three sites distributed across the Alaska boreal region in late winter, cut in 15 cm thick sections, and deep active-layer and shallow permafrost sections were thawed and leached. Leachates were analyzed for DOC, TDN, nitrate (NO 3 − ), and ammonium (NH 4 + ) concentrations, dissolved organic matter optical properties, and DOC biodegradability. Soils were analyzed for C, N, and radiocarbon ( 14 C) content. Soil DOC, TDN, DON, and DIN yields increased linearly with soil C and N content, and decreased with increasing radiocarbon age. These relationships were significantly different for active-layer and permafrost soils such that for a given soil C or N content, or radiocarbon age, permafrost soils released more DOC and TDN (mostly as DON) per gram soil than active-layer soils. Permafrost soil DOC biodegradability was significantly correlated with soil Δ 14 C and DOM optical properties. Our results demonstrate that near-surface Holocene permafrost soils preserve greater relative potential DOC and TDN yields than overlying seasonally frozen soils that are exposed to annual leaching and decomposition. While many factors control the fate of DOC and TDN, the greater relative yields from newly thawed Holocene permafrost soils will have the largest potential impact in areas dominated by organic-rich soils.

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Radiocarbon and stable carbon isotopic evidence for transport and transformation of dissolved organic carbon, dissolved inorganic carbon, and CH₄ in a northern Minnesota peatland

Cited by 193 publications

References 69 publications

Stable carbon isotope fractionation during methanogenesis in three boreal peatland ecosystems

Stable carbon isotope fractionation during methanogenesis in three boreal peatland ecosystems

A low‐blank photochemical extraction system for concentration and isotopic analyses of marine dissolved organic carbon

Dissolved organic carbon and nitrogen release from boreal Holocene permafrost and seasonally frozen soils of Alaska

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Radiocarbon and stable carbon isotopic evidence for transport and transformation of dissolved organic carbon, dissolved inorganic carbon, and CH4 in a northern Minnesota peatland

Cited by 193 publications

References 69 publications

Stable carbon isotope fractionation during methanogenesis in three boreal peatland ecosystems

Stable carbon isotope fractionation during methanogenesis in three boreal peatland ecosystems

A low‐blank photochemical extraction system for concentration and isotopic analyses of marine dissolved organic carbon

Dissolved organic carbon and nitrogen release from boreal Holocene permafrost and seasonally frozen soils of Alaska

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Radiocarbon and stable carbon isotopic evidence for transport and transformation of dissolved organic carbon, dissolved inorganic carbon, and CH₄ in a northern Minnesota peatland