Projekt

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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

Gesuchsteller/in Lehmann Moritz Felix
Nummer 121861
Förderungsinstrument Projektförderung (Abt. I-III)
Forschungseinrichtung Institut für Umweltgeowissenschaften Universität Basel
Hochschule Universität Basel - BS
Hauptdisziplin Hydrologie, Limnologie, Glaziologie
Beginn/Ende 01.12.2008 - 30.11.2011
Bewilligter Betrag 170'554.00
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Alle Disziplinen (2)

Disziplin
Hydrologie, Limnologie, Glaziologie
Geochemie

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 (Englisch)

Lead
Lay summary
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.
Direktlink auf Lay Summary Letzte Aktualisierung: 21.02.2013

Verantw. Gesuchsteller/in und weitere Gesuchstellende

Mitarbeitende

Publikationen

Publikation
Spatial variations in surface water methane super-saturation and emission in Lake Lugano, southern Switzerland
(2015), Spatial variations in surface water methane super-saturation and emission in Lake Lugano, southern Switzerland, in Aquatic Sciences, 77(4), 535-545.
Toxic effects of lab-grade butyl rubber stoppers on aerobic methane oxidationToxic effects of aerobic methane oxidation
(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.
Bacterial methanotrophs drive the formation of a seasonal anoxic benthic nepheloid layer in an alpine lake
(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.
Micro-aerobic bacterial methane oxidation in the chemocline and anoxic water column of deep south-Alpine Lake Lugano (Switzerland)
(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.

Zusammenarbeit

Gruppe / Person Land
Formen der Zusammenarbeit
Universität Neuchatel Schweiz (Europa)
- vertiefter/weiterführender Austausch von Ansätzen, Methoden oder Resultaten
- Forschungsinfrastrukturen
SUPSI Lugano Schweiz (Europa)
- Forschungsinfrastrukturen

Wissenschaftliche Veranstaltungen

Aktiver Beitrag

Titel Art des Beitrags Titel des Artikels oder Beitrages Datum Ort Beteiligte Personen
Goldschmidt Conference Vortrag im Rahmen einer Tagung Aerobic methanotrophs drive the formation of a seasonal anoxic benthic nepheloid layer in a monomictic lake 14.08.2011 Prague, Tschechische Republik Schubert Carsten; Zopfi Jakob; Blees Jan Hendrik; Lehmann Moritz Felix; Niemann Helge;
4th Congress of European Microbiologists, Vortrag im Rahmen einer Tagung METHANE OXIDATION IN THE ANOXIC HYPOLIMNION OF A DEEP SOUTH-ALPINE LAKE 26.06.2011 Geneva, Switzerland, Schweiz Niemann Helge; Schubert Carsten; Blees Jan Hendrik; Zopfi Jakob; Lehmann Moritz Felix;
Swiss Microbial Ecology Meeting Vortrag im Rahmen einer Tagung Methane oxidation in the anoxic hypolimnion of a deep south-alpine lake 02.02.2011 Engelberg, Switzerland, Schweiz Blees Jan Hendrik; Schubert Carsten; Zopfi Jakob; Niemann Helge; Lehmann Moritz Felix;
Meeting of the European Geophysical Union (EGU) Vortrag im Rahmen einer Tagung The isotopic signature of methane oxidation in a deep south-alpine lake 02.04.2010 Vienna, Austria, Oesterreich Blees Jan Hendrik; Zopfi Jakob; Schubert Carsten; Niemann Helge; Lehmann Moritz Felix;
Goldschmidt Conference Davos Vortrag im Rahmen einer Tagung Biogeochemical signatures of the anaerobic methane oxidation in a south alpine lake (Lake Lugano) 21.06.2009 Davos, Switzerland, Schweiz Schubert Carsten; Niemann Helge; Zopfi Jakob; Blees Jan Hendrik; Lehmann Moritz Felix;


Auszeichnungen

Titel Jahr
Grant for participation in competitive "Microbial Ecology" course in Woods Hole (USA) 2011

Verbundene Projekte

Nummer Titel Start Förderungsinstrument
140662 Validation and application of a novel, terrestrial biomarker-based paleo thermometer to Holocene Swiss lake sediments and soils 01.10.2012 Projektförderung (Abt. I-III)
160051 Copper availability, methanobactin production and methane oxidation in two Swiss lakes: Constraints on copper acquisition by methanotrophic bacteria 01.06.2016 Projektförderung (Abt. I-III)
153055 Seasonal Dynamics of Coupled Nitrogen, Sulfur, and Carbon Cycling in Redox Transition Zones of Lake Lugano 01.11.2014 Projektförderung (Abt. I-III)
112563 Microbial ecology and biogeochemistry of iron cycling in water columns and sediments of anoxic stratified lakes 01.12.2006 Projektförderung (Abt. I-III)
169552 The “methane paradox” in Lake Lugano - understanding methane production in oxygenated waters of lacustrine environments 01.01.2017 Projektförderung (Abt. I-III)
137636 Microbes and oxidants involved in methane oxidation in South Alpine Lake Lugano 01.12.2011 Projektförderung (Abt. I-III)
162414 Lacustrine in situ production and stable carbon isotope dynamics of branched GDGTs 01.10.2015 Projektförderung (Abt. I-III)
129491 Nitrogen elimination pathways and associated isotope effects in Swiss eutrophic Lake Lugano 01.04.2010 Projektförderung (Abt. I-III)
118111 Degradation and transformation of lacustrine organic nitrogen compounds: microbiology and biogeochemistry 01.03.2008 Resource not found: '3b845d41-c308-4023-8755-657aca6feb0d'

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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