1. 生物圈地球化学及其环境效益

2. 7.2 Organic Geochemistry
中国科学技术大学 环境地球化学概论

3. Composition of Living Matter
Proteins
Carbonhydrates
Lipids
Lignin
Vascular plants 7 50 10 33
Phytoplankton 23 66 11
Diatoms 29 63 8
Zooplankton 60 22 18
木质素 维管

4. Composition of Living Matter
Molecular Components of Biomass
Carbonhydrates and Polysaccharides
（水解多糖）

5. Composition of Living Matter
Molecular Components of Biomass

6. Composition of Living Matter
Hydrolysis Products of Biomass

7. Composition of Living Matter
Biological Breakdown of Biomolecules
(发酵)
(醋酸纤维)

8. Composition of Living Matter
Abiotic Breakdown Products of Biomass
富里酸

9. Composition of Living Matter
Complexation of Metals by Humic/Fulvic Acids OH
Some metals (Cu, Hg) are
complexed by HA and FA.
This may play a role in ore-forming processes.

10. Composition of Living Matter
Organic Carbon in Terrestrial Aquatic Systems

11. Composition of Living Matter
Organic Carbon in Sediments
Sediments contain < 1% organic C.
Nearly all DOC and POC in the water column is oxidized by respiration.
For organic C to accumulate in sediments, the flux of POC must be high and the redox conditions must be anaerobic.

12. Composition of Living Matter
Diagenesis and Kerogen Formation
Hydrolysis of complex organics
Functional groups are removed.
Double bonds are hydrogenated to give saturated hydrocarbons
Aromatic compounds increase relative to aliphatic
Condensation of molecular fragments to complex macromolecules
End product is kerogen a mixture of complex organic compounds that dominate organic matter in sediments.

13. Composition of Living Matter
Catagenesis of Kerogen to Oil and Gas
Diagenesis(成岩作用): methanogens produce methane. Organic matter converted to kerogen.
Catagenesis(后生作用): breakdown of kerogen
Metagenesis(变生作用): breakdown of oil into gas + graphite

14. Composition of Living Matter
Methane Hydrates
At the pressures and temperatures of the ocean bottom, biogenic methane is trapped as clathrates(天然水合物).

15. Composition of Living Matter
Methane Hydrates
The stability field of methane hydrates is limited to shallow sediment depths.
Methane is an extremely potent greenhouse gas and release from sediments could greatly accelerate global warming.

16. Organic Compounds
Pollution by Organic Compounds

17. Organic Compounds
Organic Pollutants: BTEX Compounds

18. Organic Compounds
Biodegradation of Organics (Cont.)

19. Organic Compounds Biodegradation of Organics (Cont.)
Spatial Distribution of electron acceptors after biodegradation progresses in soil

20. Organic Compounds
PAH (Polycyclic Aromatic Hydrocarbons) in Creosote(杂芬油)
Creosote is a common wood preservative but is now banned
because it contains PAHs(carcinogenic).
These are slow to degrade in soil.

21. Organic Compounds
Synthetic Chlorohydrocarbons

22. Organic Compounds Organohalide Breakdown by Methanogens(产烷生物)
Breakdown of vinyl chloride (CH2=CHCl) requires aerobic conditions:

23. Summary
Abiotic Breakdown of Biomolecules