Importance of carbon and water

• Importance of water in supporting life on the planet

  -key to understanding the evolution of life on earth as it allows organic molecules to mix and form more complex structures

  -increases the chance of finding life forms on the planet

  -creates benign thermal conditions e.g. oceans moderate temps by absorbing heat, storing and releasing it slowly

  -clouds reflect solar radiation and lower surface temps
• uses of water for flora, fauna and people

  -crucial for their growth, reproduction and metabolic function

  -photosynthesis, respiration and transpiration

  -to maintain rigidity ,transport mineral nutrients from the soil

  -medium used for all chemical reactions in the body

  -essential for economic activity e.g. generating electricity
• importance of carbon to life on earth

  -stored in limestone, sea floor, sediments, ocean water, atmosphere and the biosphere

  -used as economic resource e.g. fossil fuels such as coal, oil and natural gas power the global economy

  -agricultural crops and forest trees store large amounts available for humans to use
• water and carbon cycles

  -water and carbon flow in closed systems between the atmosphere, the oceans, land and the biosphere

  -at the macro scale, the global water cycle consists of three main stores atmosphere ocean and land

  -water moves between stores through precipitation, evapotranspiration, run-off and groundwater flow
• The water and carbon cycles as open and closed systems

  -On a global scale the water and carbon cycles are closed systems driven by the suns energy

  -on smaller scale maters as well as the suns energy cross system boundaries, they are called open systems

  e.g. forest ecosystem
• The global water cycle, reservoirs and stores

  -The global water cycle consists of a number of reservoirs where water is stored for variable lengths of time

  -97% of all water is stored in the ocean

  -only a tiny amount of freshwater

  -some fresh water is stored in permeable rocks
• inputs and outputs of water

  -inputs of water to the atmosphere include water vapour evaporated demo the oceans, soils, lakes and rivers and vapour transpired through the leaves of plants. this is known as evapotranspiration

  -moisture leaves the atmosphere as precipitation and condensation

  -ice sheets, glaciers and snowfields release water by ablation

  -precipitation and meltwater drain from the land surface as run-off into rivers

  -some water will infiltrate into the soil

  -after infiltrating the sail, water under gravity may percolate into permeable rocks or aquifers
• the carbon cycle

  -consists of a number of stores or sinks connected by flows of carbon

  -principle stores, the atmosphere, the oceans, carbonate rocks, fossil fuels, plants and soils

  -carbon moves between these in an never ending cycle

  -carbonate rocks and sediment are the biggest carbon store
• Slow carbon cycle

  • Carbon is stored in rocks, sea floor sediment and fossil fuels is locked away for millions of years
  • CO2 then diffuses into ocean where marine organisms creates shells and skeletons
  • When they die the remains sink to the floor and over millions of years heat and pressure convert them into carbon rich sedimentary rocks
  • Some carbon rich sedimentary rocks that are in the upper mantle and tectonic plate boundary's are vented into the atmosphere by volcanic eruptions
• Fast carbon cycle

  • Carbon circulates most rapidly between the atmosphere, the oceans, living organisms and soils
  • Land plants and microscopic plankton in the oceans are the key components of the fast cycle
  • Absorb CO2 through photosynthesis
  • Decomposition of dead organic materials returns CO2 into the atmosphere
• processes of the water cycle- flows

  the principle flows in the water cycle that link the various stores are, precipitation, evaporation, transpirations, run-off, infiltration, percolation and throughflow
• Precipitation

  -Precipitation forms when vapour in the atmosphere cools to its dew point and condenses into tiny water droplets or ice particles to form clouds

  -when rain reaches the ground it mostly goes into rivers and streams, how ever in mountainous catchments it might fall as snow and stay on the ground for several months
• transpiration

  -Diffusion of water vapour to the atmosphere from the leaf pores of plants

  -influenced by temperature windspeed and water availabiliy
• Condensation

  -it is the phase change of vapour to liquid water

  -it occurs when air is cooled to its dew point

  -clouds form through condensation in the atmosphere
• cumuliform clouds

  -with flat bases and considerable vertical development

  -form when air is heated locally through contact with earths surface, this causes heated air particles to rise freely through the atmosphere, expand and cool

  -as cooling reaches the dew point, condensation begins and cloud form
• stratiform

  layer clouds develop when air mass moves horizontally across a cooler surface
• wispy cirrus clouds

  which form at high altitude, consist of tiny ice crystals.

  • Unlike cumuliform and stratiform clouds they do not produce precipitation and therefore have little influence on the water cycle
• formation of clouds

  cooling occurs when

  -air warmed by contact with the round or sea surface, rises freely through the atmosphere, as air rises and pressure falls it cools by expansion

  -air masses more horizontally across a relatively cooler surface

  -a relatively warm air mass mixes with a cooler one
• lapse rates

  describe the vertical distribution of temperature in the lower atmosphere, and the temperature changes that occur within an air parcel as it rises away from the ground
• environmental lapse rate

  Is the vertical temperature profile of the lower atmosphere at any given time
• dry adiabatic lapse rate

  is the rate at which a parcel of dry air cools
• saturated adiabatic lapse rate

  the rate which a saturated parcel of air cools as it rises through the atmosphere
• causes of precipitation

  it develops when the tiny water droplets formed by condensation in saturated air grow until they are heavy enough to fall

  this happens either when droplets coalescing as they collide with each other in turbulent air or by ice crystals growing within clouds as they rise and fall
• catchment Hydrology- evaporation

  Evaporation-is the phase change of liquid water to vapour and is the main pathway by which water enters the atmosphere

  -the energy absorbed as latent heat is released by condesnation

  -the process allows huge quantities of heat to be transferred around the planet
• Catchment hydrology- inception

  Vegetation intercepts a proportion of precipitation, storing it temporarily on branches, leaves and stems

  rainwater that is briefly intercepted before dripping to the ground is known is through fall
• factors affecting interception loss

  INTERCEPTION STORAGE CAPACITY

  -some vegetation surfaces are dry and their ability to retain water is at a maximum

  -however as vegetation becomes saturated, output of water through stem flow through fall increases

  WIND SPEED

  -rates of evaporation increases with wind speed

  -turbulence also increases with wind speed causing additional through fall
• Infiltration, through flow, groundwater flow and run-off

  -infiltration by gravity into the soil and through flow to stream and river channels

  -overland flow across the ground surface either as a sheet or as it trickles and rivulets to stream and river channels

  -when rainfall intensity exceeds infiltration capacity, overland flow occurs

  -where soils are underlain by permeable rocks, water seeps or percolates deep underground, it then migrants slowly through through the rock pores and joints as ground water flow.
• cryospheric processes

  -ablation is loss of ice from snow

  -meltwater is an important component of rover flow in high latitudes and mountain catchments in spring and summer
• processes of the carbon cycle- precipitation

  -atmospheric co2 dissolves in rainwater to form weak carbonic acid

  -however, rising concentrations of co2 in the atmosphere due to anthropogenic emissions have increased the acidity of rainfall harming marine life
• The processes of the carbon cycle- weathering

  -Weathering is the breakdown of rocks at or near the earths surface by chemical, physical and biological processes

  -carbonation releases carbon from limestone to streams, rivers, oceans and the atmosphere

  -physical weathering by freeze thaw breaks rocks into smaller particles

  -biological weathering such as chelation contribute to rock breakdown. Rainwater mixed with dead and decaying organic material in the soil forms humid acids which attack rock minerals
• processes of the carbon cycle- respiration

  -process which carbon hydrates fixed in photosynthesis are inverted to co2 and water

  -respiration and photosynthesis are the two most important processes in the fast carbon cycle
• processes in the carbon cycle-decomposition

  -decomposed organisms such as bacteria and fungi break down dead organic matter, extracting energy and releasing co2 to the atmosphere and mineral nutrients to the soil
• carbon sequestration in the ocean

  oceans take up carbon by two mechanisms referred to as a physical pump and biological pump

  PHYSICAL

  -involves the mixing of surface and deep ocean waters by vertical currents creating a more even distribution of carbon

  -initially co2 enters the oceans from the atmosphere by diffusion, surface ocean currents then transport the water and its dissolved co2 polewards where it cools becomes more dense and sinks

  Biological

  -phytoplankton combines sunlight, water and dissolved co2 to produce organic material. Carbon is locked in the phytoplankton