ess: chapter 4 - water, food production systems and society

quantitative estimate of amounts of water in storages and flows of water cycle

• transfers (same state): flooding, infiltration, current

• transformations (changes state): evapotranspiration, condensation

ocean, soil, atmosphere, lakes

time for water molecule to enter and leave part of the system

2.6% (69% of which = frozen)

driven by solar radiation and gravity

1. withdrawals: domestic use, irrigation for agriculture and industry

2. discharges: adding pollutants

3. changing speed and locations: roads, channels, canals, dams

4. diverting rivers/sections: away to avoid floods, towards dams

urbanisation thus land cannot absorb precipitation

important in global distribution of energy

• surface currents (400m) are moved by wind and earth’s rotation

• deepwater currents/thermohaline circulation makes up the oceanic conveyor belt:

  • due to difference in density because of salt and temperature

  • cold at poles travels to the equator

  • Gulf Stream

  • climate

    • water cools and heats slower than land

    • Gulf stream heats Europe, ENSO impacts Peru

very lightly used water

dissolved minerals not evaporated after irrigation

layer of porous rock and water sandwiched between layers of impermeable rock, filled continuously by infiltration of precipitation in limited areas

• expensive, require fossil fuels, harms ocean-bottom ecosystems when salt is released

• solution to freshwater scarcity

not only when lacking, but also with unjust division in an area

who is responsible for the water? tension between common good and needs of individual (advantage for individual > individual cost) → short term worth exploiting, otherwise someone else will

when there is full natural replacement and recovery of the ecosystem

• climate change disrupts rainfall

• low water levels in rivers

• sedimentation due to slow water flow → shallower river and sea

• aquifers become exhausted → soil shrinks, agriculture difficult

• freshwater contaminated

• irrigation → salinisation

• fertilisers and pesticides → pollute

• industries and electricity plants → warm water, thus less oxygen → fish affected

• increased freshwater supply (reservoirs, redistribution, desalination, rain when harvest, artificial recharge of aquifers)

• reduce domestic use (water efficient showers, toilets)

• grey water recycling

• more efficient irrigation

• optimize area use

• reduce pesticides, use organic fertilisers

• water treatment plants in industries

dispute over unequal distribution of water (eg. Israel/Palestine, Chinese Three Gorges dam)

wild fish capture and aquaculture

farming of fish with interventions to enhance production

highest amount that can be taken without depleting stock permanently

safer version of MSY

extension of continent under sea

single celled organisms, photosynthesise, 99% of (global? marine?) primary productivity

biodiverse thus stable and resilient, over half are above continental shelf (where upwellings bring nutrient rich water, light reaches, but countries can claim)

(part of it:) continental shelf belongs to country it extends from

marine organism on/in sea bed

marine organism surrounded by water

pros:

• becoming more sustainable (their food more efficient)

• most is in rice paddies in China (mutual benefit system)

cons

• loss of habitat

• pollution (feed, antibiotics)

• spread of diseases

• escaped GMO fish interbreed with wild

• escaped outcompete native

• technology too advanced

• too small fish caught

• fleets have factory ships

• trawlers clearcut seabeds

• dead by-catch thrown back

amount of dissolved oxygen required to break down organic material by aerobic biological activity by microorganisms in given volume of water

show something about environment through presence/absence and abundance/scarcity, chosen because sensitive to change

indirectly measures pollution, assaying impact on species according to tolerance, diversity and relative abundance

when water receives input of nutrients → excess growth of plants and phytoplankton

caused by eutrophication; when not enough oxygen

1. anthropogenic or natural

2. point source or non-point source

3. organic or inorganic

4. direct or indirect

organic:

• sewage, animal waste, washing powder → eutrophication

• pesticides → loss of biodiversity

• invasive species → decimates indigenous

inorganic:

• nitrates and phosphates → eutrophication, changes biodiversity

• hot water → kills fish, changes biodiversity

• oil → contaminates birds, reduces oxygen

• noise → disrupts turtles, upsets bird cycles

BOD: current measure, indicator: summary of recent history

• anaerobic water

• loss of biodiversity

• death of plants and aerobic organisms

• increased turbidity

eutrophication with dinoflagellate; red and harmful to humans

• alter human production of pollution

• regulate pollutant where emitted

• clean up and restore