Unit 2 - Carbon Cycle, Ocean Acidification, Aquatic Biomes

Carbon found in…

• Glucose

• Atmosphere

• Oceans,

• Soil

• Fossils

• Fuels

• Rocks

Carbon cycle general definition

How carbon moves between reservoirs

Carbon Reservoirs

• Atmospheric CO₂ (main source)

• Oceans dissolved carbon

• Biosphere - plants, animals, organisms

• Soil

• Sedimentary rock

• Fossil fuels

Carbon Source vs Sink

Source —> releases more carbon than it stores

Sink —> stores more carbon than it releases

Carbon Source Examples

Respiration, volcanic activity, fossil fuel combustion, deforestation

Carbon sink examples

Forests, oceans (largest), soils

Slow Carbon Cycle places

Deep ocean + deep ocean sediments

Fossil fuels

Sedimentary rock

Turnover of slow carbon cycling vs fast

Slow - millions of years

Fast - hundreds of years

Fast carbon cycling places

Atmosphere

Vegetation

Soils

Surface ocean

Decomposition:

Thru cellular respiration: organic matter broke down and released as CO2 or stored in soil/sediment

Examples of humans increasing atmospheric CO₂

• Burning fossil fuels (coal, oil, nat gas)

• Deforestation (releases stored carbon, reduces photosynthesis)

• Land-use change

Cause of ocean acidifcation

More CO₂ in atmosphere than in ocean

What happens to dissolved CO₂ in ocean, how does it affect shelled organisms?

Water + CO₂ combine

1. CO2 + H₂O —> H₂CO₂ (carbonic acid)

Carbonic dissociates into bicarbonate + hydrogen ions

2. H₂CO₃ —> HCO₃^- + H⁺

H⁺ from carbonic binds to carbonate —> more bicarbonate

3. H⁺ + CO₃^-2 —> HCO₃^-

Shelled organisms need carbonate to make calcium carbonate

4. Ca²⁺ + CO₃^2- —> CaCO₃

Acids

Release H⁺ in water, pH lower than 7

Bases

Release OH^- in water, pH higher than 7

Stronger acids/bases in water vs weaker

Stronger —> dissociate completely in water

Each pH unit = ___ change in acid/basic concentration

10x

Freshwater Biomes

Streams, Rivers, Ponds, Lakes, Wetlands

Marine Biomes

Coastal Wetlands, Estuaries, Oceans, Coral Reefs

Rivers + Streams

Continuous current from high to low elevation, carrying nutrients + sediments

Well oxygenated water (mixing with atmosphere)

Rivers + Streams plant animal adaptations

Plants → long roots, flexible stems

Animals → streamlines bodies + good at attaching to surfaces

Lakes + Ponds

Standing slow-moving bodies of freshwater

Temperature, nutrients, oxygen vary throughout water

Lakes + Ponds plant animal adaptations

Plants → Long stems that reach toward the surface

Animals → Floating leaves maximize access to sunlight

Freshwater Wetlands general definition

Soils is saturated with or covered by freshwater for part of year

Freshwater Wetlands bogs

Waterlogged, acidic, nutrient-poor

Peat (partially decomposed plant material)

Freshwater Wetlands marshes

Herbaceous plants (grasses, reeds)

Permanently/periodically flooded

Freshwater Wetlands Swamps

Wetlands with trees + woody vegetation

Permanently/periodically flooded

Coastal Wetlands:

Salt marshes + mangrove forests

Periodic flooding

Estuaries

Where freshwater from rivers + streams meets saltwater from oceans

Variable salinity, changing water levels/conditions

Shallow + nutrient rich

Oceans

Largest marine biome (70% of earth)

High, stable salinity

Diverse depth, light, distance from shore

Coral Reefs:

Warm, shallow, clear (tropical/subtropical)

Photosynthetic algae symbiosis with coral (CaCO3)