Recomendados
Mais conteúdo relacionado
Mais procurados
Mais procurados (20)
Semelhante a Silicon cycle ppt
Semelhante a Silicon cycle ppt (20)
Último
Último (20)
Silicon cycle ppt
- 1. SILICON CYCLE SUBMITTED TO - DR. ALOK KUMAR SUBMITTED BY- PIYUSH TRIPATHI 2016MSES008 st
- 2. SILICON : GENERAL INTRODUTION • SILICON IS THE EIGHTH MOST COMMON ELEMENT IN THE UNIVERSE BY MASS • SILICON THE SECOND MOST ABUNDANT ELEMENT IN THE EARTH'S CRUST (ABOUT 28% BY MASS) AFTER OXYGEN • SILICON HAS A LARGE IMPACT ON THE WORLD ECONOMY. HIGHLY PURIFIED SILICON IS USED IN SEMICONDUCTOR ELECTRONICS: A GREAT DEAL OF MODERN TECHNOLOGY DEPENDS ON IT.
- 3. SILICON BEARING MINERALS • SIO2: QUARTZ, GLASS • SILICATES: • OLIVINES: (MG, FE)2SIO4 • PYROXENES: CA(MG,FE)SI2O6 • FELDSPARS: (NA,K)ALSI3O8 TO CAAL2SI2O8 • MICA’S: KAL2(ALSI3O10)(OH)2 • CLAY MINERALS: E.G. AL2SI2O5(OH)4
- 4. Weathering of silicates is ultimate source of all dissolved Si in water: mineral Si to dissolved Si. Transport and cycling in riverine continuum Butcher et al. 1992 Genral Outline of Silicon Cycle
- 5. THE SI IN BIOTA IS AMORPHOUS Not ordered in a tight crystal raster, like minerals It dissolves more than 1000 times faster Amorphous matrix of hydrated silica (SiO2•nH2O). A bit like:
- 6. SILICON IN TERRESTRAIL ECO SYSTEM -YEARLY PRODUCTION OF PLANT ASI, 60 – 200 TMOLE - COMPARABLE TO OCEAN ASI PRODUCTION -A MULTITUDE IS IN SOIL ORGANIC MATTER - HIGH SOLUBILITY RANGE, REACTIVE ON BIOLOGICAL TIMESCALES - ECOSYSTEMS CONTROL SI-CONCENTRATIONS IN RIVERS
- 7. FOR SOME IT’S ESSENTIAL OR CRUCIAL Horsetails Grasses and sedges
- 8. VEGETATION STORES SI “silica sheets cells” - Enhanced strength - Resistence to: Herbivores Plant disease -Reduced water, salt, pollution, stress -Enhanced productivity A beneficial element!
- 9. The crop Cattle Silicon cycle
- 10. OCEANIC SILICON CYCLE DIATOMS • DIATOMS DOMINATE COASTAL AND OCEANIC BIOGENIC SI PRODUCTION • > 10.000 SPECIES • PELAGIC AND BENTHIC FORMS • DIATOMS TAKE UP DISSOLVED SI(DSI). • DEPOSIT IT AS AMORPHOUS (BIOGENIC) SI (ASI) IN FRUSTULE
- 11. OCEANIC SILICON CYCLE CONT… DISSOLVED SILICA ESSENTIAL FOR DIATOM GROWTH IN THE OCEAN DIATOMS CONSTITUTE 50+ % OF OCEAN PRIMARY PRODUCTIVITY DSi diatom ASi 240 Tmole yr-1
- 12. CYCLING OF SILICA IN THE MARINE ENVIRONMENT
- 13. Productivity 240 Tmol y-1 Silica Burial 6.3 Tmol y-1 Eolian input 0.5 Tmol y-1 Seafloor input 0.6 Tmol y-1 Groundwater 0.4 Tmol y-1 Rivers: DSi: 6.2 Tmol y-1 ASi: 1.1 Tmol y-1 THE OCEANIC SI CYCLE – BIOLOGICAL SI PUMP Weathering 1.9 Tmol y-1 Sponges 3.1 Tmol y-1 Reverse weathering: 1.5 Tmol y-1 (based on Tréguer & De La Rocha, 2012) DSi: Dissolved Silica / ASi: Amorphous Silica
- 14. SILICON AND EUTROPHICATION Human interference (global change, habitat loss, pollution) - Expansion of agricultural activities - Reservoir construction - Urbanization - Industrialization - ...
- 15. SI AND EUTROPHICATION Expansion of agricultural activities - Increased input of N and P - Ratio of N/Si/P disturbed - Ratio determines composition of phytoplankton - Ideal molar ratio 16/16/1 Changes in composition of coastal phytoplankton Si-limitation: shift to non-diatom species Risk of collapse of foodwebs (supported by diatoms) Phaeocystis sp BLOOM Phaeocystis sp BLOOM
- 16. Ocean-continent link OCEAN SURFACE EARTH CRUST & SUBSOIL primary and secondary silicate minerals Weathering eolian transport Net riverine transport OCEAN FLOOR diatom ASi in sea- floor sediment ASi burial DSi diatom ASi 240 Tmole yr-1 6 Tmole yr-1 (*) 0.5 Tmole yr-1 6.5 Tmole yr-1 Terrestrial export of Si essential to sustain diatoms Traditional view: export controlled by bedrock weathering After Struyf et al. 2010
- 17. Tectonics OCEAN SURFACE EARTH CRUST & SUBSOIL primary and secondary silicate minerals Weathering eolian transport Net riverine transport OCEAN FLOOR diatom ASi in sea- floor sediment ASi burial DSi diatom ASi 240 Tmole yr-1 6 Tmole yr-1 (*) 0.5 Tmole yr-1 6.5 Tmole yr-1 Hydro- thermal input & Seafloor weathering plate tectonics Tectonical processes close the cycle
- 18. SILICON CYCLE (A new paradigm) Recently discovered: bio-buffer between Si weathering and export Regulates Si transport between land and ocean ECOSYSTEM SOIL 60-200 Tmole yr-1 OCEAN SURFACE EARTH CRUST & SUBSOIL primary and secondary silicate minerals Weathering eolian transport Net riverine transport OCEAN FLOOR diatom ASi in sea- floor sediment ASi burial DSi diatom ASi 240 Tmole yr-1 6 Tmole yr-1 (*) 0.5 Tmole yr-1 6.5 Tmole yr-1 Hydro- thermal input & Seafloor weathering plate tectonics
- 20. HEALTH EFFECTS OF CRYSTALLINE SILICA • SILICOSIS • CHRONIC, ACCELERATED, ACUTE • A CONTINUING PROBLEM • LUNG CANCER • TUBERCULOSIS • CHRONIC OBSTRUCTIVE PULMONARY DISORDER • OTHER • IMMUNOLOGIC DISORDERS AND AUTOIMMUNE DISEASES • RENAL DISEASE • STOMACH AND OTHER CANCERS
- 21. • USES OF SILICA : PRODUCTION OF WINDOW GLASS, DRINKING GLASSES AND BEVERAGE BOTTLES OPTICAL FIBERS FOR TELECOMMUNICATIONS ANALYTICAL INSTRUMENTS - UV SPECTROPHOTOMETER CELLS, MILITARY FIRE CONTROL DEVICES, RETICLE SUBSTRATES, INTERFEROMETER PLATES AN ADDITIVE IN THE PRODUCTION OF FOODS, PHARMACEUTICALS AND HEALTH SUPPLEMENTS, WHERE IT IS USED PRIMARILY AS A SMOOTHING AGENT (THINK PEANUT BUTTER) AND AS A FLOW AGENT IN POWDERED PRODUCTS AND IN PILL MANUFACTURE
- 22. AS A RAW MATERIAL FOR AEROGEL IN THE STARDUST SPACECRAFT IN THE EXTRACTION OF DNA AND RNA DUE TO ITS ABILITY TO BIND TO THE NUCLEIC ACIDS UNDER THE PRESENCE OF CHAOTROPES IN TOOTHPASTE AS A REFRACTORY IN FIBER FORM AS A HIGH- TEMPERATURE THERMAL PROTECTION FABRIC
- 23. REFERANCES • WOLLAST R, MACKENZIE FT THE GLOBAL CYCLE OF SILICA. IN: ASTON SR (ED) SILICON GEOCHEMISTRY AND BIOCHEMISTRY. ACADEMIC PRESS, SAN DIEGO, PP 39–76 • ENCYCLOPAEDIA BRITANNICA/ OCEANIC SILICON CYCLE • MOHERG ET AL/ SILICON IN CROPS AND CATTELS • BUTCHER ET AL/TERRESTRIAL SILICA REGULATION • WIKIPEDIA THE GLOBAL BIOGEOCHEMICAL SILICON CYCLE ERIC STRUYF&ADRIAAN SMIS&STEFAN VAN DAMME& PATRICK MEIRE&DANIEL J. CONLE • KELLER
- 24. THANK YOU