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Unit 4: Water Freshwater

• How did the oceans form? • What special adaptations do saltwater organisms

have? • Where does our water come from? • How do humans affect the Earth’s water?

Freshwater

• Freshwater

– Salinity < 0.05 %

– ~ 2.5 % of earth’s water

– 79 % found as ice in glaciers

– Only 1 % available for drinking

Freshwater

• Groundwater

– Water beneath the surface of earth

– 20 % of freshwater

• Water Table

– Level of water underground

– Near/at surface in wet regions

– 100+ m below in dry regions

Freshwater

• Surface Water

– Freshwater on Earth’s surface

– Found In:

• Lakes, Rivers, Streams, Wetlands

– Communities are built near reliable sources of surface water

Water Cycle

• Water Cycle

– Water is used in many processes of life

– Water is abundant and renewable

• Freshwater is scarce

– Split between sources (ice, ocean, atmosphere, etc.) always changes

Water Cycle

• Evaporation

– Liquid to gas

– Byproduct of cell respiration

• Transpiration

– Evaporation in plants

– Through leaves, stem, etc.

• Both require heat to occur

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Water Cycle

• Condensation

– Gas to liquid

– Creates cloud formation in the atmosphere

• Precipitation

– Rain releases water in the form of rain, sleet, snow, etc.

Water Cycle

• Groundwater

– Often ends up in ocean, river, etc.

– Taken up by plants through soil

– Humans use wells for irrigation

Freshwater Ecosystems

• Freshwater Ecosystems – Often split into flowing

and standing water

– Standing

• Slow or no motion

• Ponds, wetland, etc.

– Flowing

• Near-constant motion

• Rivers, streams, etc.

Freshwater Ecosystems

• Standing Water

– Ponds, lakes, etc.

– Often have few/no nutrients available

– Inland Sea

• Very large lake

• Animals adapted for open-water

• Ex: Great Lakes

Freshwater Ecosystems

• Littoral Zone

– Near shore

– Plants grow in mud

• Much of the nutrients are found here

• Limnetic Zone

– Away from shore, but generally lit

– No rooted plants

• Like open-ocean zone

Freshwater Ecosystems

• Wetlands

– Flooded at least part of the year

– Absorb water to prevent flooding

– Home for many commercial fish

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Freshwater Ecosystems

• Marsh

– Shallow water with many high grasses

– Ex: Meadowlands

• Swamp

– Shallow water with trees

– Ex: Bayou

• Bog

– Low nutrients and acidic water

– Often due to secondary succession

Freshwater Ecosystems

• Rivers and Streams

– Shape the landscape as they run

– Most sources in mountains

• Little life due to cold temps

– End in ocean or landlocked sea

– Flood plains are often fertile

Freshwater Ecosystems

• Estuaries

– Rivers flow into sea

• Brackish water

– Organisms tolerate high range of salinity

– High production due to nutrient collection

Freshwater Ecosystems

• Salt Marsh

– Stabilize shoreline

– Rivers leave mineral-rich mud

– Many animals grow to adulthood before going out to sea

– Ex: Chesapeake Bay

Freshwater Ecosystems

• Mangrove Forest

– Tropical regions

– Mangrove trees grow out to receive oxygen

– Protect shoreline from erosion

– Ex: Everglades

Watersheds

• Watershed – Area of land where

water drains to same place

– Also called drainage basin

– Often contains many tributaries

– Ex: Mississippi River watershed (1.2 million sq. miles)

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Watersheds

• Watershed – Small watersheds

combine into larger and end at sea

– Pollution in watershed reaches all other tributaries downstream

– Water used along watershed rivers decreases water available downstream

Groundwater

• Porosity

• Amount of space between particles in rock

• More porous rock holds more water

• Permeability • Ability of a rock to allow

water to flow through it

Groundwater

• Permeable

• Material that water can flow through (ex: gravel)

• Impermeable

• Material that water cannot flow through (ex: granite, clay)

Having more space

between individual

rocks will make the

ground more

permeable

Groundwater

• Aquifer – Underground

formation containing groundwater

– Like a sponge

– Usually contain permeable materials

– May be confined between impermeable rock

Groundwater

• Aquifer – Dry, Impermeable rock forms lower boundary

– The water table forms the upper boundary

Groundwater

• Recharge Zone

– Where surface water soaks into the ground

– Refills water in aquifer

– More permeable rock

• Quicker recharge of aquifer

– Sensitive to pollution

• Easily passes into aquifer

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Groundwater

• Well – Hole dug or drilled

for groundwater

– Usually deep into saturated zone

• Prevent drying up in drought

– Dry up if water table is below depth of well

Water Use

• Water Use – 9,087,000,000,000

m3/yr – About 70 % is used on

agriculture – Amount/split varies

based on nation’s wealth

– Global Shortage of clean water • 1/3rd of people are

affected

Water Use

• Residential Water Use – 8 % of total water use – Varies widely throughout the

world • US – 80 gal/day, India – 11

gal/day – 50 % used inside home

• Ex: cleaning, washing, etc. – ~ 50 % used outside home

• Ex: watering lawn/washing cars

Water Use

• Industrial Water Use

– 22 % of total water use

• 18 billion gal/day in US

– Manufacture goods, dispose of waste, generate power

• Most water used in industry cools power plants

Water Use

• Agricultural Water Use

– 70 % of total water use

– 80 gallons of water to produce 1 ear of corn

– About 80% of water used for agriculture evaporates before being absorbed

Water Use

• Irrigation – Watering plants

– Usually uses overhead sprinklers

• Much of the water is wasted

– Drip-irrigation is becoming common

• Individual plants are watered

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Water Diversion

• Water Diversion

– Moving water from source to where needed

– Used since ancient times

– Why?

• Bring water to make a dry area habitable

• Create reservoir

• Generate electric power

Water Diversion

• Canal

– Man-made water channels

– Built to cross impossible boundaries or divert water to dry climates

– Ex: Panama Canal

Water Diversion

• Aqueducts

– Bridges that divert water

• Often to arid climates or across valleys

– Common in ancient Rome

Water Diversion

• Dam

– Any obstruction to block flow of water

– Often used to slow water movement or prevent droughts/floods

• Reservoir

– Artificial lake created by dam

– Frequently used to provide drinking water

Water Diversion

• Dam – Benefits

• Flood control • Drinking water • Irrigation • Recreation • Industry • Electrical Energy

Water Diversion

• Dam – Costs

• Land behind dam can flood

• Nutrients blocked from reaching down river

• Displace people from homes

• Potential failure

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Water Pollution

• Water Pollution – Introduction of any

chemical, physical, or biological agents into water that:

• Degrade water quality

• Adversely affect the organisms that depend on the water

Water Pollution

• Point-Source Pollution

– Pollution from a single source

• Nonpoint-Source Pollution

– Pollution from several different sources

– Difficult to identify because they enter bodies of water many different ways

– 96% of all water pollution

Pollutants

• Pathogens – Disease-causing

organisms – Mostly from nonpoint

sources • Human/animal waste

– Most human health effects

– Ex: bacteria, viruses, protozoa, and parasitic worms

Pollutants

• Nutrient Pollution – Buildup of nitrogen and

phsophorus

– Mostly nonpoint-sources

– Seen in healthy lakes to an extent

– Lower oxygen levels and block sunlight

– Create algae blooms and red tide

Pollutants

• Toxic Chemicals – Mostly from nonpoint-sources

• Farms, lawns, Wastewater

– Organic

• Pesticides, fertilizers, detergents plastics, oil, VOC (volatile organic compounds)

– Inorganic

• Acids, salts, heavy metals

• Can affect pH levels

Pollutants

• Heavy Metals

– Cadmium: burning of fossil fuels, paint, batteries and electroplating

– Chromium: air-conditioning coolants, timber treating works, leather tanning works and electroplating

– Copper: vehicle brake pads, natural minerals, copper plumbing, irrigation water and pesticides

– Zinc: vehicle tires, motor oils, galvanizing works, corrosion from galvanized iron

– Lead: mainly car exhausts and engines

– Arsenic: brake linings, fluid leaks, vehicle emissions

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Pollutants

• Sediment Pollution

– Clouds up water to prevent photosynthesis

– Lowers water quality

– Result of runoff and erosion

– Causes: mining, clear-cutting, farming

Pollutants

• Thermal Pollution – Temperature of a body

of water rises

– Warmer water holds less oxygen

– Often due to power plants discharging water from their cooling systems

– Can also be due to tree removal

Water Pollution

• Bioaccumulation

– Buildup of pollutants higher up the food chain

– Water pollution can effect an ecosystem immediately or slowly over time

Ocean Pollution

• Ocean Pollution – ≥ 85% of ocean pollution

comes from activities on land • Runoff

– In some areas ships are allowed to dump wastewater/garbage directly into the ocean

– Affects coastlines the most

Oil Spills

• Oil Spills – 5% of ocean

pollution

– Each year:

• ~37 million gal from tanker accidents

• 200-300 mil gal from nonpoint-sources on land

Oil Spills

• Treatment

– Some oil will evaporate on its own

– Controlled burns

– Skimming from surface

– Dispersants

• Break oil into droplets

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Oil Spills

• Exxon-Valdez – March 24, 1989

– Struck a reef off the coast of Alaska

– Largest spill in US at the time

• 10,000,000+ gallons

– Remote location hindered cleanup

Oil Spills

• Exxon-Valdez

– 23,000 gallons are still in the soil near the wreck

– Killed 100,000+ seabirds, 12 otters, 22 orcas, 300 seals, 247 bald eagles

Oil Spills

• Deepwater Horizon – April 20, 2010

– Methane bubble rose out and exploded, sinking platform

– 11 workers died in explosion

– Largest spill in history

• 210,000,000 gallons

Oil Spills

• Deepwater Horizon

– Not capped until July 15, 2010

– Flooded gulf coast with oil

– BP owed > $ 42 billion as a result

Water Treatment

• Wastewater

– Water polluted from home or industrial use

– Must be cleaned before returned to a river or lake

• Water Treatment

– Process of cleaning water for drinking or industrial use

Water Treatment

• Water Treatment

– Starts with filtering large solids

– Coagulants are added

• Cause solids to form clumps called floc

• Floc settles and is pumped out

– Second filtering by fine grain sand removes remaining solids

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Water Treatment

• Water Treatment

– Chlorine is added to kill pathogens and prevent future growth

– Aeration breaks down materials and drives out unwanted gases

– Chemicals may be added (Ex: Fluoride) and the water is pumped out to consumers

Wastewater

• Sewage Sludge

– Solid material that remains after water treatment

– Often contains toxic chemicals

• Disposed as hazardous waste

– Incinerated and ashes are buried

– If toxicity can be reduced, it can be used as fertilizer

– Can be combined with clay and made into bricks