pollution & human influences on biogeochemical cycles

Energy movement

only once through an ecosystem

• from producer to consumer, then dissipating as heat

chemical elements movement

move through a cycle

• passing back and forth from organisms and physical environment

Biogeochemical cycles

mechanisms:

• biological transport

• geological transport

• chemical transport

biological transport mechanisms

absorption of chemicals by living organisms and their release back to environment

geological transport mechanisms

weathering and erosion of rocks

• elements transported by surface and subsurface drainage

chemical transport mechanisms

dissolved matter in rain and snow, atmospheric gases

Atmospheric CO2

increases when:

• plants go into hibernation during winter

decreases when:

• plants perform photosynthesis in summer

Photosynthesis

only thing that removes CO2 naturally

water cycle

solar driven evaporation moves 90% of water

• affected by humans thru:

  • dams, groundwater extraction, land use, precipitation patterns

Phosphorus & eutrophication

P has no gaseous phase

• main source = rock weathering/erosion and fertilizers

• limiting in aquatic systems

• excess can cause algal blooms = dead zones