L'oceano e la vita nell'oceano modellano la Terra

• Weathering and erosion move land-derived rock material into the ocean as rocks continually form and break down.

Note sull’adattamento (in inglese)

Describe pathways and use can for subduction and uplift rather than implying every rock or plate follows one inevitable path. Define accretion as material addition, not every process that affects a plate.

• Weathering, erosion, subduction, and uplift break down and recycle rocks.

• Rivers and atmospheric deposition deliver weathering products.
• ocean materials have different residence times.

• Dense oceanic plates subduct beneath continental plates and can cause continental uplift.

Note sull’adattamento (in inglese)

Describe pathways and use can for subduction and uplift rather than implying every rock or plate follows one inevitable path. Define accretion as material addition, not every process that affects a plate.

• Subduction can add scraped-off oceanic rocks and sediments to continental margins.
• Subduction carries some rocks and sediments into the upper mantle while other material joins the continental edge.

• Trenches, island arcs, stratovolcanoes, and some mountain ranges are associated with subduction.

• Subducted plate boundaries characterize parts of the ocean such as the Pacific Rim.

• Accretion, sedimentation, volcanism, and igneous processes continually form rocks.

• Accretion adds material to a tectonic plate.
• the diagram connects this with subduction, uplift, sea-level change, and waves.

Note sull’adattamento (in inglese)

Describe pathways and use can for subduction and uplift rather than implying every rock or plate follows one inevitable path. Define accretion as material addition, not every process that affects a plate.

• Sedimentation includes gravity settling and material moved along the seafloor by waves or currents.

• Volcanism at plate boundaries and within plates and other igneous processes create rock formations.
• Uplift and erosion expose igneous and sedimentary rocks.

• The ocean is central to biogeochemical cycles essential for life.

• Elements occur in seawater at different concentrations.
• many are essential to life, while silicon and strontium are needed by some organisms.

• The ocean is the largest reservoir of rapidly cycling organic and inorganic carbon.

• Atmospheric carbon dioxide enters through diffusion, mixing, and bubbles.
• ocean carbon occurs in dissolved organic and inorganic forms and in particles and organisms.
• Convective mixing exchanges carbon-containing materials between water layers.

Note sull’adattamento (in inglese)

Use named inorganic/organic pools rather than copying ambiguous or incomplete chemical formula lists. Do not classify methane as inorganic carbon or imply all sugars and lipids contain phosphorus or nitrogen. Describe dissolved silicon separately from particulate silica.

• www.whoi.edu

• Photoautotrophs and chemoautotrophs fix inorganic carbon into organic matter.

• Respiration converts much organic carbon back to inorganic carbon.

• Some organic carbon sinks, accumulates on the seafloor, and may become fossil fuel.

• Organisms use dissolved inorganic carbon to form calcium carbonate shells and skeletal parts.

• Much shell-derived calcium carbonate dissolves in the deep ocean.

• Some shell and coral carbonate accumulates in limestone, chalk, and carbonate banks.

• Uplift, accretion, and sea-level change can expose carbon-bearing marine rocks to weathering and erosion on land.
• Organic and inorganic sedimentary carbon both have geological return pathways through uplift, exposure and weathering.

• Fossil-fuel combustion transfers organic carbon to atmospheric carbon dioxide and affects climate and ocean pH.

• Life needs phosphorus for ATP, DNA, and phospholipids.

• Weathering of terrestrial rocks is the main ocean phosphorus source.

• Ocean phosphorus occurs in dissolved inorganic and organic forms, particles including apatite, and organisms.

Note sull’adattamento (in inglese)

Use named inorganic/organic pools rather than copying ambiguous or incomplete chemical formula lists. Do not classify methane as inorganic carbon or imply all sugars and lipids contain phosphorus or nitrogen. Describe dissolved silicon separately from particulate silica.

• www.whoi.edu

• Producers take up phosphorus, food webs transfer it, regeneration returns inorganic forms, and upwelling returns phosphorus to the surface.

• Some organic and inorganic phosphorus enters sediments and later sedimentary rocks.

Note sull’adattamento (in inglese)

Use named inorganic/organic pools rather than copying ambiguous or incomplete chemical formula lists. Do not classify methane as inorganic carbon or imply all sugars and lipids contain phosphorus or nitrogen. Describe dissolved silicon separately from particulate silica.

• www.whoi.edu

• Uplift, accretion, and sea-level changes can expose phosphorus-bearing marine rocks to weathering and erosion.

• Fertilizer and wastewater phosphorus can reach the ocean through waterways, fuel eutrophication, and alter food webs.

Note sull’adattamento (in inglese)

Treat eutrophication as nutrient enrichment that can promote blooms and alter food webs, not as a synonym for harmful algal blooms.

• www.usgs.gov

• Life needs nitrogen for amino acids and proteins.
• most organisms cannot directly use atmospheric nitrogen gas.

• Nitrogen-fixing bacteria including cyanobacteria make nitrogen available to marine life.

• Biological transformations cycle nitrogen among inorganic and organic forms through fixation, nitrification, denitrification, assimilation, ammonification, and anaerobic ammonium oxidation.
• Nitrogen forms have different oxidation states; urea is an organic nitrogen compound.

• Producers take up nitrogen, food webs transfer it, regeneration returns inorganic forms, and upwelling returns nitrogen to the surface.

• Some organic nitrogen enters sediments and becomes organic matter in sedimentary rocks.

Note sull’adattamento (in inglese)

Use named inorganic/organic pools rather than copying ambiguous or incomplete chemical formula lists. Do not classify methane as inorganic carbon or imply all sugars and lipids contain phosphorus or nitrogen. Describe dissolved silicon separately from particulate silica.

• www.whoi.edu

• Uplift, accretion, and sea-level changes expose nitrogen-bearing marine rocks to weathering and erosion.

• Nitrogen from fertilizers, wastewater, and fossil-fuel combustion reaches the ocean through water or air and can fuel eutrophication and alter food webs.

Note sull’adattamento (in inglese)

Treat eutrophication as nutrient enrichment that can promote blooms and alter food webs, not as a synonym for harmful algal blooms.

• www.usgs.gov

• Diatoms, radiolarians, and sponges use silica for hard parts such as tests, frustules, spines, and spicules.

• Weathering and volcanic activity supply ocean silica.
• rivers transport land-weathering products.

• Ocean silicon occurs in dissolved forms and in particulate minerals and biogenic skeletons.

Note sull’adattamento (in inglese)

Use named inorganic/organic pools rather than copying ambiguous or incomplete chemical formula lists. Do not classify methane as inorganic carbon or imply all sugars and lipids contain phosphorus or nitrogen. Describe dissolved silicon separately from particulate silica.

• www.whoi.edu

• Most biogenic silica dissolves after death.
• upwelling returns dissolved silicon to the surface.

• A smaller silica fraction is buried and transformed into sedimentary materials including chert, diatomite, and clay minerals.

• Uplift, accretion, and sea-level changes expose silica-bearing marine rocks to weathering and erosion.

• Human effects on weathering, including acid rain, and on the water cycle can change silica delivery to the ocean.