Water and Carbon

• open system - a system that links to each other
• closed system - a system that entirely self-contained and does not exchange matter with the environment
• positive feedback loop - a cyclic sequence that increases change
• negative feedback loop - a cyclic sequence that neutralises / stabilises change to become dynamic equilibrium
• dynamic equilibrium - state of balance within a constantly changing system
• the water cycle:

  A) evaporation

  B) transpiration

  C) precipitation

  D) runoff

  E) infiltration

  
• stores of water:

  • lithosphere - land
  • hydrosphere - liquid water
  • cryosphere - frozen water
  • atmosphere - air
• distribution of water:

  • oceans - 96.6%
  • saline water - 0.9%
  • fresh water - 2.5%
• distribution of fresh water:

  • ice
  • ground water
  • surface water
• aquifer - stores 30% of freshwater in permeable rocks
• transfer processes of water:

  • precipitation
  • transpiration
  • sublimation
  • infiltration
  • condensation
• global causes which cause change in the water cycle

  • climate change - increasing sea levels and less precipitation
  • cloud formation due to precipitation
  • cryosphere process - 95% of water is stored as ice which is melting
• local causes which cause change in the water cycle:

  • deforestation
  • urbanisation
  • agriculture
  • seasonal changes
• soil water budget:

  • changes in water stored in the soil over 1 year
• wet season:

  • precipitation > evapotranspiration = water surplus
  • ground stores fill so more runoff + higher discharge
• dry season:

  • precipitation < evapotranspiration = water shortages
• drainage basin - the area of land drained by a river or stream which is an open system
• water balance:

  precipitation = runoff + evapotranspiration + change in storage
• total runoff (%) - a measure of the total precipitation that reaches streams and rivers
• causes of variation in runoff:

  • intensity of rainfall
  • amount of plants and trees
  • soil moisture - saturated or dry
  • rock type - permeable or impermeable
• high runoff:

  • impermeable rocks
  • saturated soil
  • lack of plants
• low runoff:

  • permeable rock
  • dry soil
  • plentiful plants
• flood hydrographs are used to predict the peak discharge of a river following a flood
• short lag time + high peak

  • small basin
  • impermeable rocks and saturated soil
  • urban areas
  • heavy rainfall
• long lag time + low peak:

  • large basin
  • permeable rocks and dry soil
  • within forests
  • light rainfall
• lag time - time between peak rainfall and peak discharge
• natural affects on the water cycle:

  • precipitation
  • evaporation
  • soil water
  • vegetation
  • channel flow
• human affects on the water cycle:

  • land-uses changes - concrete leading to runoff
  • agriculture - desertification by turning land into a desert destroying biological potential
  • water abstraction - aquifers become depleted or contaminated by saltwater
• discharge = cross-section area X velocity
• precipitation - drainage systems

  • intercepted by plants
  • stored in rivers, puddles
  • infiltrates the soil
• groundwater - drainage systems

  • supplies water after precipitation
  • water held in banks and beds
• infiltration - drainage systems

  • depends on soil ability to absorb water
  • saturated soil = low infiltration capacity
  • dry soil = high infiltration capacity
• overland flow - drainage systems

  • water is unable to infiltrate so runoff begins
• throughflow - drainage systems

  • bypasses soil and is absorbed by rocks in bedrock
• The carbon cycle:

  A) burning

  B) fossil fuels

  C) decay

  D) sedimentary rock

  E) plankton

  F) soil matter

  
• carbon cycle stores:

  • sedimentary rock
  • oceans
  • fossil fuel deposits - hydrocarbons
  • soil matter - vegetation
  • terrestrial plants - converting energy into carbohydrates
• carbon cycle transfers:

  • photosynthesis - plants absorb co2 into 02
  • respiration - cellular processes
  • decomposition - dead organisms and consumed by decomposers
  • combustion - fossil fuel burning
  • burial + compaction
  • weathering
  • carbon sequestration - transferred from the atmosphere into biomass
• vegetation succession: when pioneer plants die and decay to soil carbon content increases so more species grow

  • each seral succession = more carbon
• lithosere - rocks

  hydrosere - fresh water

  halosere - salt water

  psmmosere - sand dunes

  • vegetation succession
• natural causes for changes in the carbon cycle:

  • natural climate change - co2 levels fluctuate every quaternary period
  • cold conditions - cold water holds more co2, also decomposers are less effective so more co2 is in the soil
  • warmer conditions - melting permafrost increases co2
  • wild fires
  • volcanic activity