Microbial processes of carbon and sulfur cycling at the oxic/anoxic interface in meromictic lakes

Información del proyecto

Identificador del acuerdo de subvención: INTAS-2001-02333

Proyecto cerrado

Fecha de inicio 1 Mayo 2002

Fecha de finalización 30 Abril 2005

Financiado con arreglo a

• International Association for the promotion of cooperation with scientists from the independent states of the former Soviet Union (INTAS), 1993-

Coste total

Sin datos

Aportación de la UE

€ 90 000,00

Coordinado por

Swiss Federal Institute for Environmental Science and Technology
Switzerland

Objetivo

Reactions at oxic/anoxic interfaces belong quantitatively to the most important conversion steps in the global cycles of carbon and sulfur. Over geological time scales they were of central importance during the evolution of the biosphere. In the present day earth system the microbial communities at redox boundaries control major fluxes in the global transfer of carbon and sulfur between atmosphere, hydrosphere and lithosphere. Meromictic lakes with permanent stratification and sharp boundaries between the oxic and anoxic "world" represent ideal model systems for quantitative studies of the relevant microbial reactions. Different microbial communities are spatially separated and sometimes dramatically enriched near steep redox transitions. These properties facilitate the quantitative analysis of these microbial ecosystems under in-situ conditions. The aims of the proposed research are to analyse and model microbial processes at the oxic/anoxic interfaces of different meromictic lakes and to characterize the microbial communities involved. A multidisciplinary approach will be used including microbiology, molecular ecology, isotope geochemistry, aquatic chemistry and numerical modelling. The established cooperation will allow a complementary approach based on new and well-proven methods.

The following research questions will be addressed by this project:
- What is the quantitative distribution of microorganisms belonging to different physiological groups at the oxic/anoxic interface of meromictic lakes?
- How large are the relative rates of the relevant processes contributing to carbon fixation and sulfur turnover in the meromictic zone?
- Which are the consequences of this microbial activity on nutrient cycling in the water column?

Two expeditions to meromictic lakes in Southern Siberia study (lakes Shira and Belio) and a lake in Azerbaijan (Lake Geck Gel) will be organized and carried out. A multidisciplinary aquatic systems analysis will include profiling campaigns in the water column for hydrochemical and isotopic analyses, determination of microbial rates and water sampling for detailed microbiological studies. The chemical profiles will include the major biogenic compounds and dissolved gases. Mass spectrometry will yield the carbon isotopic composition of dissolved inorganic carbon, particulate organic carbon and methane. Sulfur isotope ratios of hydrogen sulfide and sulfate will also be analyzed. Incubations with radiotracers will yield the depth distribution of microbial transformation rates such as methanogenesis and CH4 oxidation, sulfate reduction and sulfide oxidation, dark CO2 fixation and photosynthesis. The bacterial population will be estimated using most probable number techniques and fluorescent in-situ hybridisation.

Those samples for which the largest transformation rates have been detected in chemical profiles and rate measurements will be used for enrichment cultures, isolation and genetic characterization using sequencing techniques. A one-dimensional lake model will be adapted in order to determine continuous depth profiles of microbial transformation rates. The model will integrate concentration profiles and radiotracer incubations to estimate the optimum values of kinetic parameters and determine the sensitivity and uncertainty of model estimates. It will be used to determine the pathways in microbial CO2 fixation, to generalize the findings based on published values from other meromictic lakes and to quantify the nutrient cycling at the redox boundary.
The study will yield insights into the accuracy and precision of different methods for quantifying microbial reactions under field conditions. The microbial pathways which will be elucidated in two different field sites and cross-checked with other published studies will also form a solid background for ongoing studies in marine systems such as the Black Sea and other major anoxic basins of the world oceans.

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Programa(s)

• IC-INTAS - International Association for the promotion of cooperation with scientists from the independent states of the former Soviet Union (INTAS), 1993-

Tema(s)

• 4 - Life Sciences
• OPEN - OPEN Call

Convocatoria de propuestas

Datos no disponibles

Régimen de financiación

Datos no disponibles

Coordinador

Swiss Federal Institute for Environmental Science and Technology

• Aportación de la UE: Sin datos
• Dirección: Ueberlandstrasse 133 ; 8600 Duebendorf ; Suiza
• Coste total: Sin datos

Participantes (4)

Institut of microbiology of the ANAS

Azerbaiyán

• Aportación de la UE: Sin datos
• Dirección: 40 Patamdart pr. ; 370073 Baku
• Coste total: Sin datos

Russian Academy of Sciences

Rusia

• Aportación de la UE: Sin datos
• Dirección: 7/2 Prospekt 60-let Oktybry ; 117312 Moscow
• Coste total: Sin datos

Tomsk State University

Rusia

• Aportación de la UE: Sin datos
• Dirección: Lenin Av., 36 ; 634050 Tomsk
• Coste total: Sin datos

Université de Pau et des Pays de l'Adour

Francia

• Aportación de la UE: Sin datos
• Dirección: Avenue de l'universite ; 64013 Pau
• Coste total: Sin datos