A stable isotope study of the hydrological and carbon cycle in meromictic lake, Lovojärvi
Lake Lovojärvi, at its deepest point of 17.5 m, is permanently stratified forming two water layers. The mixolimnion (the upper layer, from 0 to 10 m depth) is affected by seasonal changes while the monimolimnion (bottom layer, from 10 to 17.5 m depth) does not mix and is not affected by seasonal changes. As a result, the lake stores large quantities of dissolved inorganic carbon and methane. I used a multiple stable isotope approach to gain insight into the carbon cycle and water balance of Lovojärvi. The δ18O and δ2H profiles reveal that at the 7 m depth in the mixolimnion, there is a sub-surface stream whose isotopic characteristics are similar to surface streams from a nearby mire, suggesting that this water could be coming from the mire. Measurements of δ13C-DIC and of concentrations of DIC and CH4 were used to trace carbon flow in the lake. Variations in the epilimnion of DIC concentration and of δ13C-DIC (ranging from -15.42 to -5.75‰) are explained by photosynthesis, while the strongly enriched 13C-DIC and high concentrations of DIC and CH4 in the deep water are explained by organic matter oxidation and methanogenesis. Methanotrophy appears to be an important source of carbon to the food web evidenced by the depleted 13C-zooplankton (-38.2‰). ...
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Saarela, Taija; Rissanen, Antti J.; Ojala, Anne; Pumpanen, Jukka; Aalto, Sanni L.; Tiirola, Marja; Vesala, Timo; Jäntti, Helena (Birkhaeuser Science, 2020)Freshwater ecosystems represent a significant natural source of methane (CH4). CH4 produced through anaerobic decomposition of organic matter (OM) in lake sediment and water column can be either oxidized to carbon dioxide ...
Abundance and δ13C values of fatty acids in lacustrine surface sediments : Relationships with in-lake methane concentrations Stötter, Tabea; Bastviken, David; Bodelier, Paul L.E.; van Hardenbroek, Maarten; Rinta, Päivi; Schilder, Johannes; Schubert, Carsten J.; Heiri, Oliver (Pergamon Press, 2018)Proxy-indicators in lake sediments provide the only approach by which the dynamics of in-lake methane cycling can be examined on multi-decadal to centennial time scales. This information is necessary to constrain how ...
Saarenheimo, Jatta (University of Jyväskylä, 2015)
The stable isotope composition of organic and inorganic fossils in lake sediment records : Current understanding, challenges, and future directions van Hardenbroek, M.; Chakraborty, A.; Davies, K. L.; Harding, P.; Heiri, O.; Henderson, A. C. G.; Holmes, J. A.; Lasher, G. E.; Leng, M. J.; Panizzo, V. N.; Roberts, L.; Schilder, Johannes; Trueman, C. N.; Wooller, M. J. (Elsevier Ltd., 2018)This paper provides an overview of stable isotope analysis (H, C, N, O, Si) of the macro- and microscopic remains from aquatic organisms found in lake sediment records and their application in (palaeo)environmental science. ...
Schilder, Johannes; van Hardenbroek, Maarten; Bodelier, Paul; Kirilova, Emiliya P.; Leuenberger, Markus; Lotter, André F.; Heiri, Oliver (The Royal Society Publishing, 2017)Methane-derived carbon, incorporated by methane-oxidizing bacteria, has been identified as a significant source of carbon in food webs of many lakes. By measuring the stable carbon isotopic composition (δ13C values) of ...