Florida International University Visualizing Environmental Science Exam Practice

Visualizing Environmental Science
Freshwater Resources and Water
Pollution
Chapter 10
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The Importance of Water
• Life on Earth would be impossible without
water
– All living organisms contain water
– Humans are composed of approximately 70% water
– Uses include drinking, cooking, washing,
agriculture, transportation, manufacturing, mining,
energy production, waste disposal
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The Importance of Water
• Less than 3% of Earth’s
water is consumable
(potable)
– 97% is salty
– Uneven distribution serious regional supply
issues across the globe
– By 2025, up to 2/3 of
humans will live in areas
subject to water-stressed
conditions
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Properties of Water
• The chemical structure of water gives
it unique physical properties
– Each individual molecule of water (H2O)
contains one oxygen and two hydrogen
atoms held together by strong
(covalent) bonds
– Water molecules are considered polar
molecules
• The O end of the molecule has a negative charge
• The H end of the molecule has a positive charge
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Properties of Water
• Hydrogen bonds
– Each end of every water molecule is
attracted to opposite charges on
adjacent water molecules
– This attraction forms weak chemical
bonds (hydrogen bonds) between the
molecules of H2O
– Responsible for many physical
properties of water
•
•
•
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High freezing/melting point
High boiling point
High heat capacity
Ability to act as a solvent
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The Hydrologic Cycle and Our Supply of
Fresh Water
• Surface water
– Precipitation that remains on the surface of the land
and does not seep down through the soil
• Runoff
– The movement of fresh water from precipitation and
snowmelt to rivers, lakes, wetlands, and the ocean.
• Drainage basin/watershed
– The area of land drained by a single river or stream
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Water Policy
• Florida – unique system,
water belongs to everyone in
the state equally
– Water is allocated based on a
permit system administered by
the water management
districts
– System aims to prevent waste,
provide certainty to existing
users, provide equal rights
irrespective of economic
power, and protect natural
resources
Central Ridge
Area
The Hydrologic Cycle and Our Supply of
Fresh Water
• Groundwater
– The supply of fresh water that is stored in underground
aquifers (underground reservoirs)
– Considered a non-renewable resource; takes 100s–1000s of
years to form
– Rain-fed aquifers begin at recharge zones
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Groundwater
Excess surface water seeps downward through soil and porous rock layers until it reaches impermeable rock or clay.
An unconfined aquifer holds groundwater recharged by surface water directly above it. A confined aquifer stores
groundwater between impermeable layers
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Water Resource Problems
• Three categories
– Too much water
– Too little water
– Poor-quality water
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Water Resource Problems
• Too much water
– Flooding
• Occurs when a river’s discharge cannot be contained
within its normal channel
• Humans remove water-absorbing plant cover and
construct buildings on floodplains
– Floodplains are areas bordering river channels that have
the potential to flood
• Construction replaces flood-protecting plant cover with
paved areas that do not absorb water
© 2017 John Wiley & Sons, Inc. All rights reserved.
How Development Changes the Natural Flow of Water
Shown is the fate of precipitation in Ontario, Canada, before (a) and after (b) urbanization. After
Ontario was developed, surface runoff increased substantially, from 10 percent to 43 percent.
© 2017 John Wiley & Sons, Inc. All rights reserved.
Water Resource Problems
• Too little water
– Arid lands
• Desert
• Plant growth is limited by lack of precipitation
– Semiarid lands
• Receive more precipitation than deserts, but have long
periods of drought
– Farmers use irrigation to increase agricultural
productivity of arid and semi-arid lands
• Amount of irrigated land has tripled globally since 1955
• 71% of world’s total water is used for irrigation
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Aquifer Depletion
• The High Plains or Ogallala
Aquifer
– Largest groundwater deposit in the
world
– Farmers are drawing water 40 times
faster than it can be replaced by nature
– Water table has been lowered by 4.7 –
76m
– Water conservation esp. through watersaving irrigation will postpone aquifer
depletion
This massive deposit of groundwater lies under
eight states. Water in the High Plains Aquifer
takes hundreds or even thousands of years to
renew after it is withdrawn
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Overdrawing of Surface Waters
• Overdrawing of surface waters
– Saltwater intrusion
– Wetlands dry up
– Water shortages have great economic and
ecological ramifications
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Salinization of Irrigated Soil
• Irrigation water contains small amounts of
dissolved salts
– Salinization of soil can be caused by the gradual
accumulation of salt in soil due to use of this irrigation
water
– Normally, precipitation runoff would carry salts away,
but in arid and semiarid areas there is little
precipitation, so the salts remain in the soil
– Salt accumulation becomes poisonous for plants, and
over time this salinization may render soil unfit for crop
production
© 2017 John Wiley & Sons, Inc. All rights reserved.
Water Wars
• Cooperation between countries that share
common watersheds is essential to ensure
clean water availability for all
• The river Nile… the source of wealth and prosperity for
Egypt
• Other countries are considering dam projects
• Egypt is fighting this
•
This represents just the first of many such
international and even interstate disagreements over
“shared” water sources.
Water Management
• Sustainable water use
– The wise use of water resources,
without harming the essential
functioning of the hydrologic cycle or
the ecosystems on which present and
future humans depend
– Conservation
• Includes reusing and recycling water,
improving water use efficiency
• Important part of sustainable use
– Economic policies
• If water is cheap, it tends to be wasted
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Dams and Reservoirs
• Dams generate electricity and ensure
year-round supply of water
• Dams alter river ecosystems
– Costs vs. benefits must be weighed
• Columbia River – 4th largest river in North
America
• More than 100 dams, 19 of which generate
electricity
• Negative impact on fish populations and other
aquatic organisms
• Three Gorges Dam (China) – largest in the world
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Water Conservation
• Water conservation is necessary to meet the
demands of all users
– Reducing agricultural water waste
– Reducing water waste in industry
– Reducing municipal water waste
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Conserving Water at Home
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Water Pollution
• A physical or chemical change in water that
adversely affects the health of humans and
other organisms
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Sewage
Disease-causing agents
Sediment pollution
Inorganic plant and algal nutrients
Organic compounds
Inorganic chemicals
Radioactive substances
Thermal pollution
© 2017 John Wiley & Sons, Inc. All rights reserved.
Types of Water Pollution
• BOD is a critical factor in the health of a waterway
– Large amounts of organic material
(sewage) deposited in water
enables the growth of large
numbers of microorganisms
– These microorganisms deplete
dissolved oxygen, causing fish and
the microbes themselves to then
die
– Anaerobic microorganisms then
flourish, producing toxins and
other chemicals that further
reduce water quality
Effect of sewage on dissolved oxygen
and biochemical oxygen demand (BOD)
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Eutrophication: An Enrichment Problem
• Oligotrophic lakes
– Unenriched, clear water, support small populations of
aquatic organisms
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Eutrophication: An Enrichment Problem
• Eutrophic lakes
– Cloudy water due to large numbers of algae and cyanobacteria
– Water is enriched with inorganic nutrients such as nitrogen and phosphorous
– This can be a natural, long-term process, or due to…
• Artificial eutrophication
– Overnourishment of an aquatic ecosystem by nutrients from agricultural runoff
and sewage treatment plants
© 2017 John Wiley & Sons, Inc. All rights reserved.
Sources of Water Pollution
• Water pollutants come from both natural and
human activities and they reach waterways from
either point or nonpoint sources
– Point source pollution
• Water pollution that can be traced to a specific point of
entry into a waterway (e.g. pipes, sewers, ditches)
– Nonpoint source pollution
• Pollution that enter a body of water over large areas
rather than a specific, single point of entry
– For example: Precipitation washes pollutants out of soil and
causes polluted runoff to enter local rivers over a wide area as
the runoff drains from land to the waterway
© 2017 John Wiley & Sons, Inc. All rights reserved.
Water Pollution
• Groundwater pollution
– Half of the U.S. obtains drinking water from
groundwater sources
– Quality is a concern
• Pesticides, fertilizers, organic compounds seep into
groundwater from landfills, storage tanks, backyards,
golf courses, etc.
– Cleanup is not always technically feasible
• Very costly
© 2017 John Wiley & Sons, Inc. All rights reserved.
Sources of Groundwater Contamination
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Improving Water Quality
• The best strategy for protecting water
resources is to avoid contaminating them in the
first place
– Since this is not always possible, removing
contaminants from the water supply before and
after use is the method used by most municipalities
to provide safe water for their populations
© 2017 John Wiley & Sons, Inc. All rights reserved.
Is Bottled Water Safer?
• Bottled water standards are lower than that for
municipal water.
• About one-quarter of all bottled water in the United
States is simply reprocessed municipal water, and
much of the rest is drawn from groundwater
aquifers, which may or may not be safe.
• A recent survey of bottled water in China found that
two-thirds of the samples tested had dangerous
levels of pathogens and toxins.
• Trailer: Tapped
Controlling Water Pollution
• Legislation is effective at controlling point sources of
water pollution
– Two very successful laws, but much work is still needed
– Safe Drinking Water Act – 1974
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Uniform federal standards for drinking water
Guarantees safe drinking water supply
EPA must determine maximum contaminant levels allowed
1996 amendment requires municipalities to inform which
contaminants are present and in what amount
– Clean Water Act – 1977
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Quality of rivers, lakes, aquifers, estuaries, and coastal waters
Eliminate discharge of pollutants in U.S. waterways
Attain water quality levels that are safe for fishing and swimming
EPA required to monitor national emissions limitations
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Preventing Water Pollution at Home
Individuals produce very little water pollution, but collective effect is large
© 2017 John Wiley & Sons, Inc. All rights reserved.
Controlling Water Pollution
• Water Pollution in Developing Countries
– As of 2015, 660 million people in the world do not have
access to safe drinking water
– 2.4 billion don’t have access to adequate sanitation
systems
– 1.5 billion people affected by water-related illness each
year
– Nearly 1 million of those illnesses result in death
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Visualizing Environmental Science
The Ocean and Fisheries
Chapter 11
Chapter
Chapter77
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Ocean Conveyor Belt
• Moves deep, salty sea water from higher to lower
latitudes→ water warms up
• Affects regional and global climate
• Delivers heat from
tropics to Europe
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The Gulf Stream
• The Gulf Stream is a
well-known regional
link in the ocean
conveyor belt.
• The Gulf Stream flows
northeast along the
North Carolina coast
and then out to sea,
toward Europe.
In this satellite image, the colors represent the
water’s surface temperature: red = warmest and
blue = coolest.
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Normal vs. El Niño (ENSO) Conditions
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Ocean-Atmosphere Interaction
• El Niño-Southern Oscillation (ENSO)
– Current changes during ENSO prevent upwelling, causing reduction
in nutrient availability which results in fish population declines in
shallower waters
Coastal upwelling, where deeper waters come to the
surface, occurs in the Pacific Ocean along the South
American coast. Upwelling provides nutrients for
microscopic algae, which in turn support a complex
food web.
Coastal upwelling weakens considerably during years
with El Niño–Southern Oscillation (ENSO) events,
temporarily reducing fish populations.
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Zonation in the Ocean
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Zonation Along a Rocky Shore
Three zones are shown: the supratidal, or “splash” zone, which is never fully submerged; the intertidal
zone, which is fully submerged at high tide; and the subtidal zone (part of the benthic environment),
which is always submerged. Representative organisms are listed for each of these zones.
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The Benthic Environment
• Benthic environment
– The ocean floor, which extends from the intertidal
zone to the deep ocean trenches
– Consists of sediments (sand and mud)
– Burrowing animals
• Bacteria, worms, clams, etc.
– Three zones
• Bathyal (shallowest)
• Abyssal
• Hadal (deepest)
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The Benthic Environment
• Corals: soft-bodied animals, similar to
jellyfish
– Live in hard cups or shells of calcium
carbonate
– Accumulated skeletons produce coral reefs
– Found in warm, shallow waters
– Require light for symbiotic zooxanthellae
– Also capture food with stinging tentacles
– High productivity even in poor nutrient
waters
– Most diverse marine environment – 100s of
species
– Ecologically important: habitat; protect
coastlines from erosion
– Provide humans with foods,
pharmaceuticals, recreation
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The Benthic Environment
– Sea grasses
• Flowering plants adapted to live in sea
water
• Require shallow water for
photosynthesis
• Quiet temperate, subtropical, and
tropical waters
• High primary productivity
• Ecologically important
– Stabilize sediments, reduce erosion, provide
food and habitat for marine organisms
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The Benthic Environment
• Kelps
– Largest and most complex of all seaweeds
– Brown algae
– Common in cooler temperate marine
waters
– Especially abundant in relatively shallow
waters along rocky shores
– Primary food producers for kelp “forest”
ecosystem
– Provide habitat for many marine
organisms
• Tubeworms, sponges, sea cucumbers, clams,
crabs, fishes, sea otters
– Very diverse ecosystem
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The Pelagic Environment
• Neritic province
– The part of the pelagic environment that overlies
the ocean floor from the shoreline to a depth of
200m
– Organisms are floaters (plankton) or swimmers
(nekton)
– Euphotic zone: Upper level of neritic zone
• Extends from surface to maximum depth of 150m
• Sufficient light to support photosynthetic organisms
• Phytoplankton (microscopic algae) are basis of food webs
• Zooplankton (crustaceans, jellyfish) feed on phytoplankton
• Plankton-eating nekton (herring, whales) consume zooplankton
• Carnivorous nekton (sharks, tuna) consume plankton-eating nekton
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The Pelagic Environment
• Oceanic province
– The part of the pelagic environment that overlies the ocean
floor at depths greater than 200m
– Largest marine environment (75% of water)
– Loosely described as ‘deep sea’
– Cold waters, high pressure, no light
– Life adapted to darkness and scarce food
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•
•
•
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Drifting or slow swimming, reduced bone & muscle mass
Light producing organs to locate mates or prey
Depend on ‘marine snow’ (organic debris from upper layers of ocean)
Filter feeders, scavengers, predators
Many large invertebrates, e.g., giant squid
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Marine Pollution & Deteriorating Habitat
• Paradox: ocean provides food but is used as
dumping ground
– Pollution increasingly threatens the world’s fisheries
– 80% of ocean pollution comes from human
activities on land
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Ocean Pollution has Few Controls
• Discarded plastic flotsam
and jetsam are becoming a
ubiquitous mark of human
impact on the oceans.
• 6 million metric tons of
plastic are tossed from
ships every year into the
ocean, where they ensnare
and choke seabirds,
mammals, and even fish.
• Estimated 8 plastic pieces
for every 1 zooplankton
10-15
World Fisheries
• Valuable food resources
– 90% of world’s catch is fishes
– 6% is clams, oysters, squid, octopus, and other
mollusks
– 3% is crustaceans: lobsters, crabs, shrimp
– 1% is marine algae
• World’s annual fish harvest
– 1950 – 19 million tons
– 2000 – 95 million tons
– 2012 – 91 million tons
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Problems and Challenges for the
Fishing Industry
– No nation has legal claim to open ocean
• Resources are susceptible to overuse and degradation
(Tragedy of the Commons)
– Many species have been harvested to the point where
their numbers are severely depleted
• Unstable for marine species that rely on them as part of
food web
• At least 75% of world’s fish stocks are exploited,
overexploited or depleted
– Growing human population requires protein
– Technological advances allow efficient catch, removing all fish
from an area
– 25% of all is bycatch (unintentionally caught, then discarded)
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Human Impacts – Aquaculture
• Net pens anchored in nearshore areas allow spread of diseases,
escape of exotic species and nonnative genes (GMO fish), and
release of feces, uneaten food, antibiotics, and other pollutants into
surrounding ecosystems. Plus these fish are still fed with wild caught
fish.
Offshore Extraction of Mineral
and Energy Resources
• Large deposits of minerals lie under the sea
floor
– Manganese nodules
– Offshore reserves of oil
• Major source of energy
• Major threat to fishing
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Climate Change, Sea-Level Rise,
and Warmer Ocean Temperatures
• Potential disruption of the ocean conveyor
belt, which transports heat around the globe
– Cl…
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