451816
Hydrosphere
- Properties
- Changes of state: Chemical structure, weak hydrogen
bonds, high boiling point, liquid at temperatures when its
low molecular mass would make it a gas. Water at surface
evaporates. 100°C and 1 atmosphere pressure, all H bonds
break, turns to gas as it boils. Narrow temp range of state
changes allows the hydrological cycle to occur.
- Anomalous expansion: Water molecules in ice less densely packs than as
liquid so ice floats. Water in lake cooled by cold air, as water is cooled below
4°C, molecules take up arrangement of solid, lowers density, water expands
and cold water floats. Expansion on water is unusual. Deeper, warmer water
unaffected as further cooling produces floating ice. Layer of cold water/ice
prevents water below from freezing allowing most the lake to remain unfrozen.
- Solvent: 'General physiological solvent'
most biological reactions need dissolved
water. Plant nutrients only absorbed if
dissolved in water, materials transported
in blood/sap are dissolved in water.
- High heat capacity: heats, cools slowly, maintains
climatic stability by moderating temperature changes.
- Changes of state: Chemical structure, weak hydrogen
bonds, high boiling point, liquid at temperatures when its
low molecular mass would make it a gas. Water at surface
evaporates. 100°C and 1 atmosphere pressure, all H bonds
break, turns to gas as it boils. Narrow temp range of state
changes allows the hydrological cycle to occur.
- Hydrological cycle
- RT=Vol/average transfer rate.
- Transfer rate: volume of material
moved between reservoirs.
- Residence time: average time a
molecule remains in a reservoir.
- Aquifer: underground rock
structure from which water
is abstracted.
- Processes
- Inputs: Precipitation:
impacted by global climate
change, urban heat islands.
- Throughflow: Interception: impacted by deforestation, afforestation, urbanisation.
Infiltration: impacted by soil compaction, urbanisation. Percolation: impacted by soil
compaction. Groundwater flow: impacted by groundwater abstraction, artificial aquifer
recharge, reduced infiltration/interception.
- Outputs: Evaporation: impacted by reservoirs, increased temps.
Transpiration: impacted by vegetation changes. River channel
discharge: impacted by abstraction, flood drainage.
- Inputs: Precipitation:
impacted by global climate
change, urban heat islands.
- RT=Vol/average transfer rate.
- Reservoirs
- Sedimentation - soil
erosion, reduces volume.
- Existing land use.
- Environmental effect - habitat change, river
flow changes, sedimentation, microclimate.
- Geology - rock beneath impermeable,
strong, no faults/seismic activity.
- Estuarine barrages - form freshwater lake,
water supplies, pollution and interference.
- Catchment area - water flows to reservoir.
- Topography - narrow
exit, large deep basin,
low surface area, large
volume.
- Pollution risk - land uses in catchment area not polluting.
Flooded forest, anaerobic decay, methane.
- Water supply - regular
rainfall/inflow, large
volume, not hot/dry.
- Infrastructure - better near
demand, otherwise isolated.
- Sedimentation - soil
erosion, reduces volume.
- Rivers
- River discharge, flow
fluctuations, natural
contaminants, pollutants.
- River discharge, flow
fluctuations, natural
contaminants, pollutants.
- Aquifers
- Permeability.
- Porosity - chalk,
limestone, sandstone.
- Geological structure -
impermeable below,
permeable above.
- Overuse - reduced supplies, subsidence,
surface hydrology changes (water table),
ecological, saltwater incursion.
- Permeability.
- Abstraction
- Abstractive uses - domestic, industrial, agricultural.
- Non-abstractive uses - energy, transport, recreation, conservation.
- Abstractive uses - domestic, industrial, agricultural.
- Demand and supply
- Demand - population, living standards,
industrialisation, attitude, affluence.
- Conservation and management - increasing availability , catchment
management, aquifer recharge, better distribution, inter-basin transfer,
metering, low water-use appliances, recycling grey water.
- Demand - population, living standards,
industrialisation, attitude, affluence.
- Quality - turbidity, pH, calcium content,
pesticides, heavy metals, dissolved
oxygen, chlorine retention, E. coli.
- Treatment
- Saltwater
- Reverse osmosis - filtered at high pressure through
partially permeable membrane (polyamide tubes.)
Freshwater collected, remaining salty water released.
- Distillation - water boiled, steam
condensed and collected.
- Reverse osmosis - filtered at high pressure through
partially permeable membrane (polyamide tubes.)
Freshwater collected, remaining salty water released.
- Freshwater
- Screens - remove vegetation ect.
- Sedimentation - static water,
suspended solids settle.
- Aeration - aerated, high dissolved oxygen
content, remove dissolved metals.
- Flocculation - clay particles neutralised by adding aluminium sulfate,
mixed quickly, passed into clarifier tank, particles settle.
- Activated carbon filters - activated
carbon, removes organic
chemicals.
- Filtration - filters remove suspended solids and bacteria.
- Sterilisation - addition of chlorine/ozone/UV kills pathogens.
- Fluoridation - fluorides added, improves dental health.
- Screens - remove vegetation ect.
- Saltwater
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