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Biogeochemical Research At Lake Baikal

Biogeochemical Research At Lake Baikal. Beat Müller, Lawrence Och EAWAG Federal Institute of Science and Technology of the Environment , Kastanienbaum, Switzerland Michael Sturm EAWAG Federal Institute of Science and Technology of the Environment , D ü bendorf/ Switzerland

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Biogeochemical Research At Lake Baikal

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  1. Biogeochemical Research At Lake Baikal Beat Müller, Lawrence Och EAWAG Federal Institute of Science and Technology of the Environment, Kastanienbaum, Switzerland Michael Sturm EAWAG Federal Institute of Science and Technology of the Environment, Dübendorf/Switzerland Elena G. Vologina IEC Institute oftheEarth‘sCrust, Russ.Acad.Sci., Irkutsk/Russia

  2. Focus of Scientific Interest Element budgets and fluxes: How is the lake influenced by changing loads? How do they affect the ecosystem? Quantify the loads in and out of the lake, and quantify the fluxes between reservoirs Sediment formation: Investigation of the biogeochemical processes and rates that determine the formation of the ‘young sediment’ so that the climate signals in the ‘old sediment’ can be interpreted

  3. Fluxes between reservoirs and the cycling of elements Precipitation/Deposition Import Export BIOLOGY Primary Production Export from Epilimnion (New production) Turbulence/ Advection PHYSICS Mineralization Gross Sedimentation Mineralization/ Dissolution GEOLOGY CHEMISTRY Net Sedimentation

  4. Particle Fluxes: Sedimentation • Sediment traps: • Export from Hypolimnion • Degrad. in water column • Gross sedimentation Sinking particles

  5. The Large Moorings

  6. Mooring Instruments sequencing trap (24 cups, 2 weeks interval) T-logger (10 min. intervals) current meter (30 min. intervals) Acoustic releaser integrating trap (2 cups)

  7. Particle Fluxes: Sedimentation • Sediment cores: • Net sedimentation • Mineralization/Dissolution sediments

  8. Processes at the Sediment-Water Interface • Mineralization of organic matter • Consumption of oxidants • Release of nutrients water sediments

  9. Mineralization and Dissolution O2 concentration profiles mm

  10. Mineralization and Dissolution In average: 3 mmol O2 m-2d-1 O2 concentration profiles => 1.1 mio t O2 a-1 mm => 92 km3 of water (a layer of 3m thickness) i.e. Mineralization of => 880’000 t algae a-1

  11. Fluxes in the water column Advection: Estimation of annual cold-water intrusions into the deep water of the Lake Turbulent mixing: Determination of vertical diffusivity with temperature microstructure measurements and inertial diffusivity eg. Sibio N P Upwel- ling Cold water intrusions

  12. Fluxes in the water column CDT Probe Temp. logger

  13. Fluxes of Phosphorus (South Basin) 50 10 Pin Sed. traps 80 40 Pflux Water column 30 difference Pin Sed. traps 50 Pflux Porewater 20 25 difference Pin Sediments 25 kt P yr-1

  14. Fluxes of Phosphorus (South Basin) 50 kt P yr-1

  15. Monitoring of Tributaries Selengaisthemaintributarydischarging 50 % ofthewaterload 75 % oftheparticleload 50 % ofterrestrialorganiccarbon Reliablemonitoringdataof hydrology majorelements, nutrients suspendedparticles are essential toestimate elementbudgets longtermchanges

  16. Sediment Formation Sediment formation: Investigation of the biogeochemical processes and rates that determine the formation of the ‘young sediment’ so that the climate signals in the ‘old sediment’ can be interpreted

  17. Early diagenetic processes in the sediment Formation at the redox interface Upper layer moves up with sedimentation Lower layer stays in place Observed in layers of up to 65’000 years What causes the detachment? Indicators of changes in the catchment (climate?) What happens here?

  18. Early diagenetic processes in the sediment

  19. Early diagenetic processes in the sediment

  20. Diagenetic Processes of the Fe/Mn layer O2 Oxidation of Mn(II) by O2 Reduction of Mn(IV) by Corg, Fe Reduction of Fe(III) by Corg Diffusion of Mn(II) Diffusion of Fe(II) Fe(II) reduces Mn-oxide Diffusion Fe(II) Oxidation by Fe-oxide Diffusion CH4 Methanogenesis

  21. Development of Fe/Mn layers Mn Fe

  22. Thank you

  23. Summary Nutrient Budgets • SB NB • New Production20.8 14.6gC m-2 yr-1 • Net Sedimentation 2.6 1.5gC m-2 yr-1 Fluxesof N, P andSibiowere 30% smaller in the NB than in the SB. Denitrificationrates 37 (SB) and 52 (NB) mmol m-2 yr-1. (cf. 57 mmol m-2 yr-1foroceans (Middleburg et al., 1996)) 10.6 and 6.0 mmol P m-2 yr-1weretransferredtothedeepwater in the SB and NB where 26% and 42% P wereretained in thesediments.

  24. Structure of the buried crust: Micro-XRF Profiles

  25. Peeper Plate after Exposition

  26. Fluxes of Organic Carbon (South Basin) Corg in Sed. traps O2 flux Water column 20.8 20.8 7.2 6.2 difference difference Corg in Sed. traps 14.6 13.6 sum O2 flux Porewater 11.0 12.0 difference Corg in Sedimens 2.6 gCm-2yr-1

  27. SILIKAT im Sediment-Porenwasser Rücklösung:0.56 mmol/m2 d bei 31’500 km2…180’000 t Si/Jahr Jährlicher Eintrag aus dem Einzugsgebiet:250’000 t Si/Jahr

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