globalchange  > 气候变化与战略
DOI: 10.1016/j.epsl.2020.116459
论文题名:
Chemocline collapse in Lake Kivu as an analogue for nitrogen cycling during Oceanic Anoxic Events
作者: Uveges B.T.; Junium C.K.; Scholz C.A.; Fulton J.M.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 548
语种: 英语
中文关键词: chemocline ; nitrogen cycle ; Oceanic Anoxic Events ; pigment biomarkers ; stable isotopes
英文关键词: Biomarkers ; Mixing ; Nitrogen ; Nutrients ; Organic carbon ; Sulfur compounds ; Well testing ; Bacteriochlorophylls ; Carbon enrichment ; Dissolved inorganic carbon ; Nitrogen isotopes ; Oceanic Anoxic Event ; Photosynthetic pigments ; Primary producers ; Water column mixing ; Lakes ; anoxic conditions ; biomarker ; carbon isotope ; deposition ; lacustrine deposit ; meromictic lake ; nitrogen cycle ; nitrogen isotope ; sapropel ; water column ; East African Lakes ; Lake Kivu
英文摘要: One of the outstanding issues in the study of nutrient dynamics during Oceanic Anoxic Events (OAEs) is the preservation of 15N-depleted nitrogen isotope signals, which are not observed in analogous modern environments. The favored mechanism for δ15N values below 0‰ is utilization of excess ammonium derived from underlying anoxic waters by primary producers. However, there are few modern examples available for testing this hypothesis, due to the overall well-oxygenated state of modern oceans. Here, we present sedimentary δ13Corg and δ15Nbulk data, as well as pigment biomarker ratios, from the sediments of Lake Kivu, a meromictic lake in East Africa. This system serves as a potential analogue for the development of strongly depleted δ15Nbulk in OAE black shales. We focus on intervals of organic carbon enrichment (sapropels) that are interpreted to have been the result of lake water column mixing events. Sediment δ13Corg and δ15Nbulk decrease by up to 6 and 4‰ respectively near the base of sapropel layers. These negative excursions provide evidence for the mixing of 13C-depleted dissolved inorganic carbon and ammonium in excess of photosynthetic need, derived from the deeper anoxic basin of the lake. Support of this model is also provided by photosynthetic pigment biomarkers which show significant fluctuations in phototrophic ecology consistent with water column mixing and changes in nutrient status. Further evidence for the shallowing of the chemocline during sapropel deposition is found in the presence of bacteriochlorophyll derivatives produced by phototrophic sulfide oxidizers. © 2020 Elsevier B.V.
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165320
Appears in Collections:气候变化与战略

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作者单位: Department of Earth Sciences, Syracuse University, 900 South Crouse Avenue, Syracuse, 13244, United States; Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, United States; Department of Geosciences, Baylor University, One Bear Place #97354, Waco, TX 76798, United States

Recommended Citation:
Uveges B.T.,Junium C.K.,Scholz C.A.,et al. Chemocline collapse in Lake Kivu as an analogue for nitrogen cycling during Oceanic Anoxic Events[J]. Earth and Planetary Science Letters,2020-01-01,548
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