scholarly journals Methane in Lakes: Variability in Stable Carbon Isotopic Composition and the Potential Importance of Groundwater Input

2021 ◽  
Vol 9 ◽  
Author(s):  
Jonathan Schenk ◽  
Henrique O. Sawakuchi ◽  
Anna K. Sieczko ◽  
Gustav Pajala ◽  
David Rudberg ◽  
...  
Keyword(s):  
Carbon Isotopic Composition ◽  
Isotopic Fractionation ◽  
Boreal Lakes ◽  
Stable Carbon ◽  
Deep Lake ◽  
Subarctic Lakes ◽  
Carbon Isotopic ◽  
Deep Waters ◽  
Littoral Sediments ◽  
Different Characteristics

Methane (CH4) is an important component of the carbon (C) cycling in lakes. CH4 production enables carbon in sediments to be either reintroduced to the food web via CH4 oxidation or emitted as a greenhouse gas making lakes one of the largest natural sources of atmospheric CH4. Large stable carbon isotopic fractionation during CH4 oxidation makes changes in 13C:12C ratio (δ13C) a powerful and widely used tool to determine the extent to which lake CH4 is oxidized, rather than emitted. This relies on correct δ13C values of original CH4 sources, the variability of which has rarely been investigated systematically in lakes. In this study, we measured δ13C in CH4 bubbles in littoral sediments and in CH4 dissolved in the anoxic hypolimnion of six boreal lakes with different characteristics. The results indicate that δ13C of CH4 sources is consistently higher (less 13C depletion) in littoral sediments than in deep waters across boreal and subarctic lakes. Variability in organic matter substrates across depths is a potential explanation. In one of the studied lakes available data from nearby soils showed correspondence between δ13C-CH4 in groundwater and deep lake water, and input from the catchment of CH4via groundwater exceeded atmospheric CH4 emissions tenfold over a period of 1 month. It indicates that lateral hydrological transport of CH4 can explain the observed δ13C-CH4 patterns and be important for lake CH4 cycling. Our results have important consequences for modelling and process assessments relative to lake CH4 using δ13C, including for CH4 oxidation, which is a key regulator of lake CH4 emissions.

scholarly journals Stable Carbon Isotopic Composition in Annual Rings of a Pine Tree (Pinus Densiflora) from Yeongwol, Korea: Possible Application to Climate Study

Radiocarbon ◽  
2017 ◽  
Vol 59 (2) ◽  
pp. 373-381
Author(s):  
Chi-Hwan Kim ◽  
Jang Hoon Lee ◽  
Jin Kang ◽  
Sujin Song ◽  
Myung-ho Yun ◽  
...  
Keyword(s):  
Tree Rings ◽  
Pinus Densiflora ◽  
Stable Carbon Isotope ◽  
Carbon Isotopic Composition ◽  
Precipitation Data ◽  
Stable Carbon ◽  
Climate Data ◽  
Carbon Isotopic ◽  
Pine Tree ◽  
Paleoclimate Proxy

AbstractStable carbon isotope ratios were measured on the alpha-cellulose in tree rings of a pine tree (Pinus densiflora) from Yeongwol, Korea. We developed an annual-resolution δ13C series (1835–1905) by correcting the measured data for changes in δ13C of air to minimize non-climatic influences. To investigate the climatic signal in the δ13C series, we performed correlation analysis between δ13C and the Cheugugi climate data. The Cheugugi precipitation data were first recorded by King Sejong (1397–1450) of the Joseon Dynasty. However, the longest set of precipitation data available is the one collected in Seoul (1776–1907). Although many studies support the reliability of the Cheugugi data, no previous studies have investigated the potential of the δ13C signal in tree rings as paleoclimate proxy using the Cheugugi data. Recent precipitation trends in Yeongwol are quite similar to that of Seoul, and we found significant correlations between the Cheugugi data and the δ13C series. We suggest further studies to replicate these results and confirm whether comparing δ13C variations in tree rings and Cheugugi data is a useful method of investigating the potential of the δ13C signal as a paleoclimate proxy in or near the Korean peninsula.

scholarly journals Environmental influences on the stable carbon isotopic composition of Devonian and Early Carboniferous land plants

2019 ◽  
Vol 531 ◽  
pp. 109100 ◽  
Author(s):  
Zhenzhu Wan ◽  
Thomas J. Algeo ◽  
Patricia G. Gensel ◽  
Stephen E. Scheckler ◽  
William E. Stein ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Environmental Influences ◽  
Carbon Isotopic Composition ◽  
Early Carboniferous ◽  
Land Plants ◽  
Stable Carbon ◽  
Carbon Isotopic

scholarly journals Radiocarbon in Porewater of Continental Shelf Sediments (Southeast Mediterranean)

Radiocarbon ◽  
2004 ◽  
Vol 46 (2) ◽  
pp. 633-642 ◽  
Author(s):  
O Sivan ◽  
B Lazar ◽  
E Boaretto ◽  
Y Yechieli ◽  
B Herut
Keyword(s):  
Sediment Cores ◽  
Carbon Isotopic Composition ◽  
Mediterranean Coast ◽  
Shelf Water ◽  
Stable Carbon ◽  
Last Glacial Period ◽  
Carbon Isotopic ◽  
Shelf Sediments ◽  
Water Depths ◽  
The Last Glacial

In this study, we aim to characterize the main processes controlling 14CDIC concentrations in porewater at the shallow shelf (water depth less than 120 m) off the Mediterranean coast of Israel. At these water depths, we expected to find evidence for seawater penetration toward the coast, since this area was flooded by seawater only some 18,000 yr ago (the end of the Last Glacial period).Measurements of the chemical composition (14CDIC) and stable carbon isotopic composition (δ13CDIC) were performed in several sediment cores (40–250 cm long) at water depths between 6 and 115 m. At water depths of 60 m, represented by a 2.5-m-long sediment core, the porewater 14CDIC levels (85–87 pMC) were lower than the corresponding sediment values in each layer (92–95 pMC), mainly due to the oxidation of relatively old organic matter (about 70 pMC) with no evidence to advection. In contrast, sediment cores from water depths shallower than 50 m showed only slight anaerobic oxidation and high 14CDIC values of approximately 100 pMC, indicating possible downward advection. These geochemical observations support the perception that the penetration of seawater into the coastal aquifer occurs at the shallow water zone (<50 m), while further verification by deeper cores is required.

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.

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