Unit 4: Water, Food Production Systems & Society Flashcards
What are 4 reasons why water is important?
- keeps us alive
- moderates climate
- sculpts land
- removes and dilutes wastes and pollutants
How does water sculpt land?
erosion
What percent of the earth’s water supply is available to us as liquid freshwater?
1%
What percent of all water is saltwater?
97%
What percent of all water is freshwater?
2.6%
What percent of freshwater is frozen? (for now)
68.7%
What percent of freshwater is groundwater?
30.1%
What percent of Earth’s total water volume is available on the surface in lakes, rivers, and swamps?
0.3%
If 2.6% of all water is fresh, then why is only 1% of the earth’s water supply available to us?
2/3 of freshwater is frozen, so we cannot use it
What percent of the total Earth’s water volume is water vapor in the atmosphere?
0.001%
If all of the water in the atmosphere rained down at once, to what depth would it cover the ground?
2.5 cm
When is a resource renewable?
a resource is renewable if it is replenished on a human time scale
How long does it take a molecule of water to enter and leave a river storage?
12-20 days
How long does it take a molecule of water to enter and leave an atmospheric storage?
9 days
How long does it take a molecule of water to enter and leave a groundwater storage?
up to 300 years
How long does it take a molecule of water to enter and leave an ice cap storage?
16,000 years
How long does it take a molecule of water to enter and leave an ocean storage?
37,000 years
How can water easily go from being a renewable to a non-renewable resource?
poor management
Which water storages are renewable?
atmosphere and rivers
Which water storages are non-renewable?
oceans and icecaps
What water storage is a middle ground (either renewable or non-renewable)?
groundwater aquifers
What is the water cycle powered by?
solar radiation (the Sun)
What can water flows either be?
transfers or transformations
What are 5 types of transfers that occur in the water cycle?
- advection
- flooding
- surface run-off
- infiltration and percolation
- stream flow and current
advection
wind-blown movement
infiltration and percolation
when water runs into and through soil or rocks
What are 3 types of transformations that occur in the water cycle?
- evapotranspiration
- condensation
- freezing
evapotranspiration
liquid to water vapor
condensation
water vapor to liquid
What are the seven storages in the water cycle?
- oceans
- soil
- groundwater (aquifers)
- lakes
- rivers and streams
- atmosphere
- glaciers and icecaps
What are 4 ways humans impact the water cycle?
- withdrawals
- discharges
- changing flows (the speed at which water can flow and where it flows)
- diverting rivers
What are 3 uses for humans to withdraw water?
- domestic
- irrigation
- industry
How do humans interrupt the movement of water through discharges?
adding pollutants to water (chemicals from agriculture, fertilizers, sewage)
How do humans change flows in the water cycle?
creating dams, reservoirs, and channels
Why do humans divert rivers?
rivers are directed away from important areas or towards dams to improve storage
canalizing
converting a river into a navigable canal, leading to more rapid flow
permeable surfaces
allow water to percolate into the soil to filter out pollutants and recharge the water table
impermeable surfaces
solid surfaces that do not allow water to penetrate it, forcing it to run off
What has water from the Aral Sea mostly been used for?
irrigation
Since 1961, what has happened to the Aral Sea’s salinity levels?
The Aral Sea’s salinity levels have tripled.
How much has the water dropped in the Aral Sea?
22 meters
Where does most water from the Middle East come from?
the Nile, Jordan, Euphrates, or Tigris rivers
What percent has lake Chad in Africa shrunk by?
95%
What are 3 things many parts of the world experiencing?
- rivers running dry
- falling water tables from over pumped aquifers
- lake and seas shrinking
How many people live without clean drinking water?
1.1 billion
How many people lack adequate sanitation?
2.6 billion
How many people die every year from diarrheal diseases?
1.8 million
How many children die everyday from waterborne diseases?
3,900
How many river basins are shared by 2 or more countries mostly without adequate legal or institutional arrangements?
over 260
What quantity of water is needed to produce 1 kg of wheat?
1,000 liters
What quantity of water is needed to produce 1 kg of rice?
1,400 liters
What quantity of water is needed to produce 1 kg of beef?
13,000 liters
What is the daily water usage per person in residential areas in North America and Japan?
350 liters
What is the daily water usage per person in residential areas in Europe?
200 liters
What is the daily water usage per person in residential areas in sub-Saharan Africa?
20 liters or less
What is the leading human use of water?
agriculture
What are the 6 human uses of water?
- domestic
- agriculture
- industry
- electricity
- transportation
- boundaries
How do humans use water for transportation?
ships on lakes and rivers
How do humans use water for domestic purposes?
water used at home for drinking, washing, cleaning, etc.
How do humans use water for agriculture?
irrigation, for animals to drink
How do humans use water for industry purposes?
manufacturing, mining, cooling
How do humans use water for electricity purposes?
most turbines are powered by steam
How do humans use water as boundaries?
rivers and lakes mark boundaries between nation states
How much higher is agriculture water use than domestic water use?
agriculture water use is 10 times higher than domestic water use
What percent of human water use is for irrigation and electricity?
70%
What percent of human water use is for industries?
20%
What percent of human water use is for cities or residences?
10%
What term does the UN use to refer to our current situation?
“water crisis”
What percent of humans alive today deal with some level of water scarcity?
up to 40%
It isn’t that there’s not enough water world wide…
it’s that the water isn’t evenly distributed
water scarcity
the demand for water exceeds available resources
physical water scarcity
when the demand of the population exceeds the available water resources of a region
economic water scarcity
when human, institutional, or financial capital limit our access to water even though water in nature is available for human needs
Do poor households in developing countries or families in industrialized nations spend higher portions of their income on water?
poor households in developing countries spend more money on water
What would sustainable use allow for?
full natural replacement of the resources exploited and full recovery of the ecosystems
What are two sources of freshwater?
surface water and aquifers
What are examples of surface water?
rivers, streams, reservoirs, and lakes
aquifer
a layer of porous rock (holds water) adjacent to a layer of impermeable rock (does not let water through)
What do aquifers hold?
groundwater that can be extracted directly from the surface or via wells
watershed/drainage basin
land where surface runoff drains downhill into a body of water
reliable runoff
amount of surface runoff that is consistently available for use from year to year
What happens to reliable runoff?
it soaks into the ground and becomes groundwater
In what kind of places can aquifers be refilled?
aquifers can only be refilled in places where the porous rock is exposed at the surface and infiltration from precipitation
What happens to “fossil aquifers” that are no longer exposed at the surface?
the “fossil aquifers” are never recharged
How is the flow in an aquifer?
VERY slow
What can be done to aquifers?
aquifers can be opened or confined
What are the two types of aquifers?
renewable aquifers and non-renewable aquifers
natural recharge
aquifers are replenished naturally by precipitation and percolation
lateral recharge
aquifers are recharged from the side by nearby streams and lakes
At what speed do renewable aquifers recharge?
slowly
Where are non-renewable aquifers located?
deep underground
How long ago did non-renewable aquifers form?
formed tens of thousands of years ago
What is an example of a non-renewable aquifer?
Ogalla
Where is the Ogalla aquifer located?
under the Great Plains
What are the effects of over pumping groundwater?
subsidence and salt water intrusion
salt water intrusion
when the water table is lowered the normal interface moves inland, allowing saline water to penetrate freshwater aquifers
subsidence
the gradual caving in or sinking of an area of land, which can lead to sink holes
What percent of water that we withdraw from rivers, lakes, and aquifers is not returned to these sources?
70%
consumptive use
water does not return to its original source, instead it returns to a different stage in the hydrologic cycle
nonconsumptive use
water is used and returned, and only temporarily removed
What are seven issues related to freshwater use?
- climate change
- low water levels in lakes and rivers
- slow water flow
- pumping too fast from aquifers
- pollution (freshwater is contaminated)
- irrigation degrades soil
- thermal pollution
How do low water levels in lakes and rivers affect the economy?
low water levels can make navigation impossible
How does slow water flow eliminate wetlands?
slow water flow causes deposition of sediments which fills streams, eliminating wetlands
What is an effect of pumping water too fast from aquifers?
pumping water too fast causes a cone of exhaustion/depression, making the well unusable
How does irrigation degrade soil?
evaporated water leaves dissolved minerals on the surface, causing salinization
salinization
when the dissolved mineral remain on the top layer of soil, making it too salty for further agriculture
How does climate change alter the freshwater supply?
climate change disrupts weather patterns, leading to more severe droughts or floods
How does thermal pollution affect freshwater supplies?
industries and power plants release warm water into rivers, affecting dissolved oxygen
In 2005, how many people lacked access to enough clean water for drinking, cooking, and washing according to the UN?
1 in 6 people
What percent of the world’s population lives in river basins that do not have enough freshwater?
41%
What are 5 consequences of not having access to freshwater?
- war
- less food, famine
- use of dirty water
- disease
- mass emigration/immigration
What are 8 possible solutions to problems related to freshwater use?
- increase supply
- reduce domestic use
- closed system car washes
- grey water recycling
- irrigation (drought resistant crops, efficient irrigation methods)
- reduce pesticide/fertilizer use
- treat polluted or industrial water
- regulate maximum temperature of cooling water
How would one increase freshwater supplies?
reservoirs, desalination plants, rainwater harvesting systems, artificially recharging aquifers
What is one way we can reduce domestic water use?
low flow toilets
ocean currents
the movement of water both vertically and horizontally
Why is ocean water constantly sinking near the poles?
colder temperatures hold more salt and increase water density, so as a result of gravity water sinks
What 2 factors affect ocean density?
- temperature
- salinity
What happens to cold currents?
cold water that sinks crawls to the equator over the course of 100 years
What do ocean currents play an important role in?
the global distribution of energy
Coriolis effect
the effect that Earth’s rotation has on winds and ocean currents
What percent of ocean currents are deep water currents?
90%
What does the Coriolis effect cause?
deflection towards circular patterns
In what direction do objects deflect as a result of the Coriolis effect in the northern hemisphere?
towards the right
In what direction do objects deflect as a result of the Coriolis effect in the southern hemisphere?
towards the left
How do surface currents get energy?
surface currents get energy from the friction between the wind and the ocean’s surface
What are deep currents also called?
thermohaline currents
What do warm currents do?
distribute heat from the equator towards the poles
gyre
a large system of swirling ocean currents
How many major ocean gyres are there?
5
What is an example of a location in which warm currents flow from the equator to the poles?
the Gulf Stream (in the North Atlantic Ocean)
What is the climate like near land close to seas?
mild, with moderate winters and cool summers
What effect does water have on temperature?
it stabilizes it
Why do water masses heat up and cool down more slowly than landmasses?
water has a higher specific heat capacity than land
What effect does the Gulf Stream have on Northwestern Europe?
Northwestern Europe is warmer than it should be
What current is the Namibian desert cooled by?
the Benguela current
What does ENSO stand for?
El Niño Southern Oscillation
teleconnections
changing conditions in one part of the world can affect areas far from the source
Why do currents reverse during El Niño?
trade winds weaken (sometimes reverse), so there is nothing holding the water up
What are 3 local effects of El Niño?
- collapse of anchovy fish stocks
- massive death of sea birds
- storms and flooding in the coastal plain of Peru
upwelling
when cold nutrient-rich waters come up from the ocean depths as a result of wind blowing across the ocean surface
How are ocean temperatures affected during El Niño?
ocean surface warms, sea surface temperatures are above average
What effect does El Niño tend to have on rainfall?
rainfall increases over the Pacific Ocean, while it decreases over Indonesia
How are ocean temperatures affected during La Niña?
ocean surface cools, sea surface temperatures are below average
What effect does La Niña tend to have on rainfall?
rainfall decreases over the Pacific Ocean, while it increases over Indonesia
What happens to trade winds during La Niña?
normal easterly winds along the equator become stronger
How often do El Niño events occur?
every 2-8 years
How long do El Niño events last?
about 2 years
What are 6 examples of marine ecosystems?
- oceans
- mangroves
- estuaries
- lagoons
- coral reefs
- deep ocean floor
What is the result of diversity in marine ecosystems?
stability and resistance
continental shelf
the extension of continents under the seas and oceans
What are 4 reasons why the continental shelf is important?
- over 50% of marine productivity but 15% of its area
- upwelling
- plenty of light reaches shallow seas so producers can photosynthesize
- countries can claim it as theirs to exploit and harvest
What is the continental shelf also known as?
neritic zone
benthic
live on or in the ocean floor
pelagic
live in the water
Since fish are not evenly distributed, where do most fish reside?
places with high productivity
What percent of ocean primary productivity do phytoplankton produce?
99%
phytoplankton
single-celled photosynthetic organisms
zooplankton
single-celled animals that eat phytoplankton and their waste
fishery
a fishery exists when fish are harvested in some way, it includes capture of wild fish, as well as aquaculture or fish farming
What percent of fishery activity is in the ocean?
90%
What percent of fishery activity is in freshwater?
10%
How many people rely on fisheries for their livelihood?
up to half a billion people
How many people get at least 20% of their protein from fish?
3 billion
According to FAO (Food and Agriculture Organization of the United Nations), what percent of world’s fisheries are fully exploited, in decline, depleted, etc?
70%
aquaculture
the farming of aquatic organisms in both coastal and inland areas involving interventions in the rearing process to enhance production
Which 8 species of fish are all you need to meet your nutrient requirements?
- white sea bass
- walleye
- rainbow trout
- cobia
- arctic char
- yellowtail
- Atlantic salmon
- coho salmon
What are 3 ways in which fish farming has become more sustainable?
- fishmeal (feed) uses more trimming and scraps (sometimes livestock and poultry waste) that would have just been discarded
- 8 species of fish can get one enough nutrients from alternative sources without eating other fish
- carp and catfish are grown within rice paddies (polyculture practice that integrates rice agriculture with aquaculture, so fish waste fertilizes plants)
What are 4 negative impacts of fish farming?
- loss of habitat (sometimes Mangrove forests are removed for fish farms)
- pollution
- spread of diseases
- escaped species can become invasive or spread “GMO” genes
The FAO estimates what percent of fisheries are under threat of overexploitation?
75%
bycatch
unwanted fish and other marine animals that are thrown back into the ocean after being caught
How are we so good at finding and catching fish? (3 ways)
- satellite and GPS technology of military quality
- large fishing fleets (boats used in the fishing industry) use modern refrigeration techniques to stay at sea for weeks
- indiscriminate fishing gear takes all organisms in an area, whether they are the target species or not
How much fish is bycatch per year?
20 million tonnes
What do bottom trawlers do to the ocean floor?
drag huge nets over the seabed virtually clearcutting it
What are 6 fishing practices?
- longline
- purse seine
- bottom trawling
- drift net
- sonar
- planes
longline fishing
placing very long lines with thousands of baited hooks
purse seine fishing
a large net deployed around a school of fish that acts like a fence, and then a boat drives around it and pulls the strings tight
What has purse seine fishing killed a large number of?
dolphins that live at the surface
bottom trawling
use of a net dragging along the bottom of the ocean
What is a side effect of bottom trawling?
bycatch
What is comparable to bottom trawling?
clear-cutting forests
How many dolphins, whales, turtles, and sharks are killed by drift nets?
10,000
In 1992, the UN placed a ban on drift nets longer than what?
1.5 miles
drift netting
nets hang vertically, and are kept upright by weights on the bottom and floats on the top
sonar
uses sound waves to detect schools of fish
How many tonnes of fish does the world catch per year?
just over 90 million
How many tonnes of fish goes to fish meal to feed animals?
23 million
In general, what percent of animal protein eaten by humans is fish?
15%
What are 2 reasons why fish stocks are shrinking?
- industrialized countries subsidize (financially support) their modern fishing fleets by and estimated $50 billion per year
- demand is greater than supply
Why do individuals tend to overexploit resources?
the advantage to taking the resource is greater than the cost to the individual
What is often the solution to the “tragedy of the commons”?
regulation and legislation
irrigation
any means used by humans to bring water to land
When are irrigation methods used?
used when rainfall is either inconsistent/does not provide enough natural water to grow crops
How much of the world’s land is irrigated?
about half
How long have humans been using irrigation?
thousands of years
What are the 3 most common types of irrigation?
flood (furrow), drip, spray
How does excess water from irrigation/run off contribute to pollution?
run off carries dissolved salt and pesticide residues into local water supplies
What is the percent efficiency for flood irrigation?
60%
flood irrigation
when water is pumped/carried to fields and allowed to flow over the ground
What is the percent efficiency for drip irrigation?
90-95%
drip irrigation
when water is sent to crops through pipes that have holes in them, resulting in less salinization
Which 2 irrigation methods are expensive to install?
- center-pivot
- drip irrigation
Why does drip irrigation use 25% less water than flood irrigation?
less is lost to evaporation
What is the percent efficiency for spray irrigation?
65%
spray irrigation
when water is through pipes at high pressure though a nozzle that requires electricity and wastes a significant amount of water (evaporation/wind)
What is the percent efficiency for LEPA (low energy precision application)?
95%
LEPA (low energy precision application)
modified sprinklers that minimize wind and evaporation losses by running water directly onto the soil
What is the percent efficiency for center-pivot irrigation?
80-95%
center-pivot irrigation
low pressure spray that moves in a circle
What are 8 ways to increase irrigation efficiency?
- soil moisture detectors
- mulching
- growing deep root plants
- import water intensive crops/meat
- line irrigation canals/ditches
- plastic covers over plants
- xeriscaping
- treat waste water for irrigation
xeriscaping
using native vegetation/stones to decorate yard, reducing need for extra irrigation
Why cover plants with plastic?
plastic traps moisture
sustainable yield
the natural income that can be exploited each year without depleting the original stock or its potential for replenishment
maximum sustainable yield
the highest amount that can be taken without permanently depleting the stock
What are the 3 things that affect a species carrying capacity?
- the species reproductive strategy
- how long individuals live
- resources available in a habitat/ecosystem
What are 3 reasons why harvesting the maximum sustainable yield still usually leads to population decline?
- predictions (in regards to the maximum sustainable yield) are not always accurate
- disease may strike/something else unaccounted for
- sex ratios may get thrown off
When can the sustainable yield be harvested?
when the amount of individuals entering a population is greater than the amount of individuals leaving
How does one calculate the sustainable yield?
SY = (annual growth and recruitment) - (annual death and emigration)
optimal sustainable yield (OSY)
maximizes the revenue to cost ratio, has a much greater safety margin, and requires less effort
What do fishing quotas usually set as?
a percentage of OSY (weight of catch not number of fish) per fleet per year
water pollution
the contamination of bodies of water by pollutants either directly or indirectly
What are the types of water pollution?
anthropogenic or natural, point source or non-point source, organic or inorganic, direct or indirect
What are 4 examples of freshwater pollution?
- agricultural run off
- sewage
- industrial discharge
- solid domestic waste
What are 5 examples of marine pollution?
- rivers
- pipelines
- the atmosphere
- human activities at sea
- discharge (both on purpose and accident
anthropogenic pollution
created by human activites
What is an example of natural pollution?
volcanic eruption
What are 11 types of aquatic pollution?
- organic material
- inorganic plant nutrients
- toxic metals
- synthetic compounds
- suspended solids
- hot water
- oils
- radioactive material
- pathogen
- light
- noise
- invasive species
BOD (Biological Oxygen Demand)
a measure of the amount of dissolved oxygen required to breakdown the organic material in a given volume of water through aerobic biological activity by microorganisms
biotic index
indirectly measures pollution (on a scale of 1-10) by assaying the impact on species within the community according to their tolerance, diversity, and relative abundance
indicator species
plant and animal species that show something about the environment by their presence, absence, abundance, or scarcity
What effect does the “biodegradation” of organic material have on the BOD?
certain pollutant increase the BOD, leading to anoxic conditions
Can warm or cold water hold less dissolved gases?
warm water can hold less dissolved gases than cold water
eutrophication
when lakes, estuaries, and coastal waters receive inputs of nutrients which result in an excess growth of plants and phytoplankton
What are the 6 steps of eutrophication?
- fertilizer runs off into a river/lake
- high nutrient levels makes algae grow faster (particularly phosphate)
- algal blooms form (mats of algae) that block out light to plants beneath them that die
- zooplankton and small animals at the surface feed on on algae, they are food to fish which multiply as there is more food so there are fewer plankton to eat the algae
- algae die and are decomposed by aerobic bacteria
- there is not enough oxygen in the water, so the food chain collapses
What are the 5 effects of eutrophication?
- water ways are covered by green scum/duckweed
- give off smelling gases like hydrogen sulfide
- loss of biodiversity
- increased turbidity of water
- lack of oxygen
Where do the high levels of nutrients come from during eutrophication? (5 things)
- detergents (major phosphate source)
- fertilizers
- livestock runoff
- sewage
- increased erosion of topsoil
What are 3 strategies for managing eutrophication?
- altering human activity producing pollution
- regulating/reducing the pollutants at the point of emission
- clean up and restoration
US Clean Water Act
sets standards for allowed levels of key water pollutants
What is the goal of the US Clean Water Act?
maintain physical, chemical, biological integrity of the water
Is the US Clean Water Act successful?
good for point source pollution, but needs to improve regulations for non-point source pollution
preliminary treatment
a physical process that uses bar screens to remove large floating objects from raw sewage
What objects does the bar screen remove during preliminary treatment?
non flushable tissues, sanitary products, corn, guns, and body parts
primary sewage treatment
a physical process where the sewage moves to a large tank, slows down, giving solids time to settle; solids sink to the bottom and oils float to the top, and sludge is removed and sent to digesters
secondary sewage treatment
a biological process in which aerobic bacteria remove biodegradable, oxygen demanding organic wastes
aeration tank
removes organic materials and nutrients using bacteria; bacteria needs lots of oxygen because they are aerobic decomposers
What are examples of organic wastes that aerobic bacteria remove during secondary sewage treatment?
human waste, soaps, detergents, food waste, e. coli, phosphates, nitrates
plant effluent
water that leaves the plant
Where is the sludge from primary sewage treatment disposed?
landfill, ocean, cropland, pasture, or rangeland
Why is water after secondary sewage treatment chlorinated?
water is chlorinated to remove coloration and kill disease-carrying bacteria and some viruses (ex: e. coli, coliform, giardia, chlorea)
advanced/tertiary sewage treatment
a chemical and physical process to remove nitrates and phosophates
When is advanced/tertiary sewage treatment required?
only required if discharging into surface waters
What is used as a disinfectant during advance/tertiary sewage treatment?
UV and sand for extra filtration
What are other ways to clean/filter water?
charcoal, cloth, nano filters, boiling
US Safe Drinking Water Act
requires the EPA to establish national drinking water standards
The US Safe Drinking Water Act does not applied to bottled water, who regulates bottle water?
FDA
maximum contaminant level
the maximum concentration of a chemical that is allowed in public drinking water systems
In regards to the US Safe Drinking Water Act, what does the maximum contaminant level apply to?
any pollutant that may have adverse effects on human health
