Project
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Biogeochemical fluxes in South-Alpine Lakes: Linking nitrogen and methane dynamics in lacustrine redox-transition zones using a combined stable isotope and molecular approach
Applicant |
Lehmann Moritz
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Number |
121861 |
Funding scheme |
Project funding (Div. I-III)
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Research institution |
Institut für Umweltgeowissenschaften Universität Basel
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Institution of higher education |
University of Basel - BS |
Main discipline |
Hydrology, Limnology, Glaciology |
Start/End |
01.12.2008 - 30.11.2011 |
Approved amount |
170'554.00 |
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All Disciplines (2)
Hydrology, Limnology, Glaciology |
Keywords (15)
nitrogen cycle; denitrification; anammox; methanogenesis; methane oxidation; stable isotopes; biomarkers; microbial community structures; Lake Lugano; benthic nepheloid layer; nitrogen; methane; biogeochemical cycles; diagenetic reactions; anaerobic methane oxidation
Lay Summary (English)
Lead
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Lay summary
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Bioavailable nitrogen (N) from anthropogenic sources is an important driver of lake eutrophication. However, N loading in lakes is partially mitigated by microbially mediated processes that take place in redox transition zones (RTZ) within the water column and in sediments. RTZ are also sites of methane (CH4) and nitrous oxide (N2O) production and consumption. As a result of anthropogenic activities, emissions of these greenhouse gases to the atmosphere have significantly increased over the past decades.Lake Lugano is an excellent model system for an anthropogenically impacted lake that represents a hot-spot of quantitative redox-driven transformations involving the green house gases CH4 and N2O, as well as other N species acting as important macro nutrients. Previous studies have revealed that this lake represents an important sink for fixed N and that the anoxic deep-waters and sediments contain high concentrations of CH4. Through the application of stable isotopic, molecular ecological and geochemical techniques, laboratory cultivation and (radio-) tracer studies, the project will try (i) to understand the metabolic pathway involved in N and CH4 elimination in Lake Lugano, (ii) to assess the metabolic rates, at which the respective elimination processes take place, as well as their variability in time and space, (iii) to constrain the isotope effects associated with specific N and CH4 transformations, and (iv) to provide information about the microorganisms involved in these transformations. Thereby, a particularly focus is put on reactions that have essentially been neglected in lake studies thus far, namely the anarobic oxidation of ammonium (anammox) and the anaerobic oxidation of methane (AOM). The project will provide the first comprehensive characterization of early diagenetic reactions in Lake Lugano. Moreover, it may allow insights into novel modes of autotrophic life in lakes. Finally, quantitative estimates of N and CH4 elimination in both the water column and sedimentary RTZ of Lake Lugano will be a prerequisite for ecosystem-scale N and C budgets. Thus, the project will provide important information that is directly pertinent to the health of Lake Lugano in particular, and eutrophied south alpine lakes in general.
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Responsible applicant and co-applicants
Employees
Publications
Blees Jan, Niemann Helge, Erne Markus, Zopfi Jakob, Schubert Carsten J., Lehmann Moritz F. (2015), Spatial variations in surface water methane super-saturation and emission in Lake Lugano, southern Switzerland, in
Aquatic Sciences, 77(4), 535-545.
Niemann Helge, Steinle Lea, Blees Jan, Bussmann Ingeborg, Treude Tina, Krause Stefan, Elvert Marcus, Lehmann Moritz F. (2015), Toxic effects of lab-grade butyl rubber stoppers on aerobic methane oxidationToxic effects of aerobic methane oxidation, in
Limnology and Oceanography: Methods, 13(1), 40-52.
Blees Jan, Niemann Helge, Wenk Christine B., Zopfi Jakob, Schubert Carsten J., Jenzer Joël S., Veronesi Mauro, Lehmann Moritz F. (2014), Bacterial methanotrophs drive the formation of a seasonal anoxic benthic nepheloid layer in an alpine lake, in
Limnology and Oceanography, 59(4), 1410-1420.
Blees Jan (2014), Micro-aerobic bacterial methane oxidation in the chemocline and anoxic water column of deep south-Alpine Lake Lugano (Switzerland), in
Limnology and Oceanography, 59(2), 331-324.
Collaboration
Universität Neuchatel |
Switzerland (Europe) |
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- in-depth/constructive exchanges on approaches, methods or results - Research Infrastructure |
SUPSI Lugano |
Switzerland (Europe) |
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- Research Infrastructure |
Scientific events
Active participation
Title |
Type of contribution |
Title of article or contribution |
Date |
Place |
Persons involved |
Awards
Grant for participation in competitive "Microbial Ecology" course in Woods Hole (USA)
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2011
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Associated projects
Number |
Title |
Start |
Funding scheme |
140662
|
Validation and application of a novel, terrestrial biomarker-based paleo thermometer to Holocene Swiss lake sediments and soils |
01.10.2012 |
Project funding (Div. I-III) |
160051
|
Copper availability, methanobactin production and methane oxidation in two Swiss lakes: Constraints on copper acquisition by methanotrophic bacteria |
01.06.2016 |
Project funding (Div. I-III) |
153055
|
Seasonal Dynamics of Coupled Nitrogen, Sulfur, and Carbon Cycling in Redox Transition Zones of Lake Lugano |
01.11.2014 |
Project funding (Div. I-III) |
162414
|
Lacustrine in situ production and stable carbon isotope dynamics of branched GDGTs |
01.10.2015 |
Project funding (Div. I-III) |
112563
|
Microbial ecology and biogeochemistry of iron cycling in water columns and sediments of anoxic stratified lakes |
01.12.2006 |
Project funding (Div. I-III) |
118111
|
Degradation and transformation of lacustrine organic nitrogen compounds: microbiology and biogeochemistry |
01.03.2008 |
Interdisciplinary projects |
169552
|
The “methane paradox” in Lake Lugano - understanding methane production in oxygenated waters of lacustrine environments |
01.01.2017 |
Project funding (Div. I-III) |
137636
|
Microbes and oxidants involved in methane oxidation in South Alpine Lake Lugano |
01.12.2011 |
Project funding (Div. I-III) |
129491
|
Nitrogen elimination pathways and associated isotope effects in Swiss eutrophic Lake Lugano |
01.04.2010 |
Project funding (Div. I-III) |
Abstract
Bioavailable (“fixed”) nitrogen (N) from anthropogenic sources is an important driver of lacustrine eutrophication. However, N loading in lakes is partially mitigated by microbially mediated processes that take place in redox transition zones (RTZ) within the water column and in sediments. RTZ are also sites of methane (CH4) and nitrous oxide (N2O) production and consumption. As a result of anthropogenic activities, emissions of these greenhouse gases to the atmosphere have significantly increased over the past decades. The role of lakes (i) as a terrestrial sink for fixed N and (ii) in the global CH4 budget are still poorly constrained. Furthermore, modes of suboxic N2 production and CH4 consumption, other than denitrification and aerobic CH4 oxidation, respectively, have barely been investigated in lakes, and the microbial communities involved in CH4 and N transformations in lacustrine RTZ are mostly unknown.Lake Lugano is an excellent model system for an anthropogenically impacted lake that represents a hot-spot of quantitative redox-driven transformations involving the green house gases CH4 and N2O, as well as other N species acting as important macro nutrients. Previous studies have revealed that this lake represents an important sink for fixed N and that the anoxic hypolimnion and sediments contain high concentrations of CH4. We propose to address the following main research questions:1.)What are the different metabolic pathways of suboxic N2 production in the Lake Lugano water column and in sediments? What are the respective transformation rates and fluxes? Which organisms are responsible for observed N transformations?2.)What are the rates and metabolic pathways of CH4 oxidation in the lake’s RTZ? What is the identity and relative abundance of microorganisms involved?Employing novel tools, the proposed research efforts will aim to investigate the concentration, distribution and isotopic composition of inorganic nitrogenous compounds, CH4, and biomarkers in order to assess the processes that are responsible for the observed geochemical signatures, thereby linking community structures and biogeochemical activities. These data, in combination with basic 16S rDNA analyses, laboratory cultivations, and (radio-) tracer experiments, will help us (i) to understand the metabolic pathway involved in N and CH4 elimination in Lake Lugano, (ii) to assess the metabolic rates, at which the respective elimination processes take place, as well as their variability in time and space, (iii) to constrain the isotope effects associated with specific N and CH4 transformations, and (iv) to provide information about the microorganisms involved in these transformations. We will particularly focus on reactions that have essentially been neglected in lacustrine studies thus far, namely the anarobic oxidation of ammonium (anammox) and the anaerobic oxidation of methane (AOM). We will also investigate potential links between the N and CH4 cycles (i.e., the coupling of denitrification and AOM). We will specifically examine AOM and/or anammox in the benthic nepheloid layer in the South Basin of the lake, with the particular goal to elucidate the mechanisms behind its formation.The research proposed here will result in the first comprehensive characterization of early diagenetic reactions in Lake Lugano. Moreover, this research may help gain insights into novel modes of autotrophic life in lakes. Quantitative estimates of N and CH4 elimination in both the water column and sedimentary RTZ of Lake Lugano will be a prerequisite for ecosystem-scale N and C budgets. Moreover, estimates of isotope effects of specific C and N transformations in the modern lake will provide the basis for paleolimnological extrapolation. Thus, the proposed research will help us address biogeochemical processes that are important for the general understanding of a complex ecosystem both today and in the past. It will also provide useful information that is directly pertinent to the health of an important Swiss water body.
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