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Why study the marine silicon cycle?. Major nutrient needed by Si mineralizers Diatoms Role in biogeochemical cycles Link to carbon cycle. Silicate. Structural material Diatoms Radiolarians Silicoflagellates Sponges. Silica in Water. Silicon dioxide
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Why study the marine silicon cycle? • Major nutrient needed by Si mineralizers • Diatoms • Role in biogeochemical cycles • Link to carbon cycle
Silicate • Structural material • Diatoms • Radiolarians • Silicoflagellates • Sponges
Silica in Water • Silicon dioxide • SiO2 + 2H2O H4SiO4 • H4SiO4 (monosilicic acid) • Three forms: • Reactive • Colloidal • Suspended particles
Inputs: • Riverine = 80% • Aeolian deposition = 7% • Dissolution of seafloor basalts = 7% • Hydrothermal vents = 6%
Bloom ‘n’ Bust Lifestyle • Bloom • Spring • High nutrients and light • Bust • Depletion of nutrients, esp. silicon • Sink • Resting spores
What’s so good about this? • Sinking diatoms export from the atmosphere into the ocean interior • Diatoms play a key role in the biogeochemical cycle of silicon in the ocean • Biogenic silica in diatom skeletons acts as an effective pH buffer, facilitating the conversion of bicarbonate to dissolved CO2