Tracing Biophysical and Biological transformations of organic matter using spectroscopy

Transcription

1 Tracing Biophysical and Biological transformations of organic matter using spectroscopy Isabel Reche and many coauthors Departamento de Ecología Universidad de Granada Granada, Spain

2 Tracing Biophysical transformations A fraction DOM behaves as a polymer gel: DOM selfassembles to POM DOM undergoes phase transitions phase linked to ph changing its shape and size

3 Tracing Biophysical transformations Polymers self-assembly POM + Ca chelator (EDTA) DOM After Orellana & Verdugo 2003 L&O 48: Techniques: Size of polymer gels- Dynamic Laser Scattering (DLS) Shape of polymer gels- Scanning Electron Microscopy (SEM) Shape and Size- Atomic Force Microscopy (AFM) After Chin et al Nature 391:

4 Tracing Biophysical transformations Polymers self-assembly and phase transitions in lake waters In collaboration with P.Verdugo; M.L. Pace; J.J. Cole; I.P. Mazuecos; A. Fernández-Barbero

5 Tracing Biophysical transformations Polymers self-assembly in lake waters 9000 Hummingbird Lake 8000 Hydrodynamic diameter (nm) POM DOM DOC= 1517 µm Ca 2+ = 39.3 µm Incubation time (h) Hydrodynamic diameter (nm) Mean 2000 Mean±SE Mean±SD POM DOM DOC= 358 µm Ca 2+ = 26.8 µm Paul Lake Incubation time (h) Hydrodynamic diameter (nm) Mean Mean±SE 5000 Mean±SD POM Peter Lake 0 DOM Incubation time (h) Mean Mean±SE Mean±SD DOC= 433 µm Ca 2+ = 37.3 µm

6 Tracing Biophysical transformations 6000 Hummingbird lake + EDTA 4000 Paul lake + EDTA Hydrodynamic diameter (nm) POM DOM No EDTA + 2 µl EDTA + 4 µl EDTA Ca 2+ chelation using EDTA Mean 0.95*Min-Max Hydrodynamic diameter (nm) POM DOM No EDTA + EDTA Ca 2+ chelation using EDTA Mean 0.95*Min-Max Selfassembly of DOM polymers from lake waters also is mediated by calcium

7 Tracing Biophysical transformations ph-phase transitions Swelled phase Swelled/hydrated phase Condensed phase POM DOM Condensed phase After Chin et al.1998 Nature 391: Techniques: Size of polymer gels- Dynamic Laser Scattering (DLS) Shape of polymer gels- Scanning Electron Microscopy (SEM) Shape and Size- Atomic Force Microscopy (AFM)

8 Tracing Biophysical transformations ph-phase transitions 17 Hummingbird lake Hydrodynamic diameter (nm) Condensed phase Hummingbird lake Swelled/hydrated phase DOM ph generated using HNaCO 3 POM Absorption coefficients at 440 nm (m -1 ) Photobleaching coefficients x 10-3 (Em -3 ) Swelled/hydrated phase ph generated using HNaCO 3 Swelled/hydrate d phase Experimental ph We measured simultaneously mean size, absorbance and photobleaching rates

9 SEM AFM ph=5.59 ph= µm 5 µm 20 µm 0 µm 0 µm 10 µm 20 µm 0 µm 0 µm 10 µm 20 µm 20 µm 0.2 µm 0.0 µm 0.1 µm 0.0 µm Techniques: Shape of polymer gels- Scanning Electron Microscopy (SEM) Shape and Size- Atomic Force Microscopy (AFM) Author: Ignacio P. Mazuecos

10 The working hypothesis for underlying mechanisms

11 Tracing Biophysical transformations CONCLUSION: DOM changes its conformation (shape and size) depending on ph (phase transition) with consequences for its optical properties (absorption and photobleaching)

12 Krill excretion

13 Krill excretion Krill megaswarm 1000 ind m -3 Smetacek &Nicol 2005

14 Krill excretion B- Tyrosine like M-Marine humic like

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16 Krill excretion 0.2 µm filtered water Control Antarctic krill Euphasia superba Role as consumer, prey and fertilizer Hourly incubations Daily incubations

17 Krill excretion CDOM Final time CDOM Initial time = CDOM generated by krill excretion Final time krill Initial time krill

18 Bacterial DOM processing

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20 Bacterial DOM processing GF/F filtered water Control Photoproducts Quartz SOLAR EXPOSURE to t1 t1 tn Incubation 2ºC Analysis: CDOM Bacterial abundance Bacterial Production

21 Bacterial DOM processing CDOM Final time CDOM Initial time = CDOM generated by bacterial growth Deception Island Livingston Island

22 Bacterial DOM processing and viral lysis Labile DOM Refractory DOM-CDOM 15-30% Lytic cycle DOM?? In collaboration with N. Mladenov; E. Ortega-Retuerta; D. Winget; C. Suttle

23 Bacterial DOM processing and viral lysis CONTROL Final EEM Initial EEM + PARAFAC CONTROL Absence of viruses Final EEM Initial EEM + PARAFAC time 1, R2 time 1, R2 time 5, R2 time 5, R2

24 Bacterial DOM processing and viral lysis + labile C, N,P Final EEM Initial EEM + PARAFAC + labile C, N, P Absence of viruses Final EEM Initial EEM + PARAFAC time 1, R2 time 1, R2 time 5, R2 time 5, R2

25 CONCLUSIONS: Absorbance scans over time can trace signatures of processes as diverse as krill excretion (hourly & daily) and bacterial DOM processing on different substrates. Emission-Excitation Matrices over time and PARAFAC modeling can trace bacterial growth on different substrates and under viral lysis.