Earth Systems and Resources – College Board
C. Global water resources and use:• Freshwater/saltwater• Ocean circulation• Agricultural (use)• Industrial and domestic use• Surface and groundwater issues• Global problems• Conservation
Aquatic Ecology – Terms
• Abyssal zone • Aphotic zone• Bathyl zone• Benthos (benthic)• Currents • El Nino• Estuary
• Euphotic• Eutrophic• Freshwater biome• Inland wetlands• Intertidal zone• Limnetic • Littoral
• Marine biome • Nekton • Oligotrophic• Photic zone• Plankton• Riparian zones
• Runoff• Thermocline• Transition zone• Turbidity• Upwelling • Watershed
Properties of Water • Hydrogen bonding - creates properties of
water that enable life to exist 1. High heat capacity2. High heat of vaporization3. Expands as it freezes4. Universal solvent5. Adhesive/cohesive
Properties of Water • High heat capacity
• Changes temperature slowly• Uneven heating/cooling creates winds,
currents• Moderates climate
• Cold places are warmer, warm places are cooler• High heat of Vaporization – as water
evaporates, it removes heat• Evaporative cooling
Universal Solvent• Water can dissolve a lot of compounds
• Nitrates, K, Ca, glucose making them available to cells
• It can easily become polluted by water-soluble wastes
Properties of Water
• Expands as it freezes• Most dense at 4oC• Ice forms at the surface • Upwelling - cooler water rises to the
surface, bringing nutrients into the photic zone
• Turnover
Thermal Stratification• In summer, the surface water
is warm - less dense (lighter)• Thermocline - middle layer
prevents the transfer of nutrients from the bottom and dissolved oxygen from the top• Oxygen dissolves into water at
the surface• Poop and dead stuff floats to the
bottom – nitrogen cycle
Fall Turnover• Temperature begins to fall• Surface layer becomes more dense• Sinks to the bottom• Nutrients circulate to the surface and
oxygen to the bottom• Upwelling • Winter – layers are fairly even
Spring Turnover
• Ice melts; cold water warms up • Sinks below the cooler (less dense)
water• Oxygen circulates down and
nutrients (nitrates) circulate to top (photic)
Aquatic Life Zones
• Abiotic factors determine who lives where:• Sunlight • Salinity• Turbidity • Temperature • Dissolved oxygen
• Two aquatic biomes – fresh and marine
Marine Biomes – 71 % of Earth
• Economic benefits:• Food• Oil, natural gas,
minerals• Transportation • Recreation
• Ecological benefits:• Moderates climate• Habitat and nursery
areas • Absorbs CO2 (CaCO3)• Reduces storm impact
Life Zones
• Plankton – float or weak swimmers• Phytoplankton – algae; Diatoms (1o
producer)• Euphotic zone
• Zooplankton – 1o consumers• Necton – good swimmers • Benthos – (benthic) bottom dwellers
(barnacles, oysters)• Decomposers: breakdown organic compounds
(mostly bacteria)
Coastal Biome• High tide to continental shelf• 90% of all marine life
Estuary
• Where the river meets the oceans• Bays, inlets, sounds, salt marshes,
mangrove swamps
• Highly productive (1o productivity)• Nutrient-rich nurseries• Filter toxins • Prevent beach erosion
Coastal Zones
• Salt marsh - nursery for many fish• Lots of 1o production• Prevent beach erosion• Filters toxins
• Intertidal zone – between high and low tides
• Coral reef - slow growing coral animals build reefs• Mutualism with zooxanthellae algae • Close to surface
Open Ocean
• Pelagic• Euphotic zone• Bathyal zone • Abyssal
Stratification
• Abiotic factors vary with depth: • Temperature• Sunlight • Dissolved oxygen • Nutrient availability
• Euphotic zone - sunlight can penetrate
Lakes• Littoral zone (near shore, shallow, with
rooted plants)• Limnetic zone (open, offshore area, euphotic)• Profundal zone (deep, open water, aphotic)• Benthic zone (bottom of lake)
Lake Nutrients
• Oligotrophic - ‘few feed’ • Not many food chains• Low nutrients
Lake Nutrients
• Eutrophic – lots of nutrients • Shallow, murky; filled with
sediment
Cultural Eutrophication• Human activities add too much nutrient
to lake
Freshwater Inland Wetlands
• Reduce flooding, erosion caused by storms
• Replenish streams• Recharge groundwater • Habitats• Nursery, spawning grounds• Filter toxins (salt marsh)
Peat Moss Bog
• A wet area that over time fills in (the last stage of succession is peat moss).
• Can be very deep. • May be burned as fuel.
Water Cycle• Runoff - water that does
not sink into the ground or evaporate
• Watershed or drainage basin - the land that drains water into a lake or river
Surface Water
• Can be flowing (rivers/streams) or standing (lakes, ponds, wetlands)
• Source – precipitation• Watershed – Ex. small streams larger
streams rivers sea
Rivers and Streams• Deliver nutrients to sea • Deposit silt that maintains deltas• Purify water• Renew and renourish wetlands• Provide habitats for wildlife
Headwaters • Cold, clear water; waterfalls and rapids• High amounts of dissolved oxygen (DO)• Oxygen diffuses into water at the surface• Many headwaters form a stream/river
Downstream Characteristics
• Waters spread out, move more slowly, warmer temperatures, less DO
• Algae and cyanobacteria• Littoral zone grows more emergent
plants
Freshwater • Groundwater - precipitation that penetrates
(percolates) the ground and is stored underground (aquifer)
• Aquifers–porous rock w/ water flowing through
• Water Table – the level of earth’s land crust to which the aquifer is filled
• Renewability – the circulation rate of groundwater is slow (300 to 4,600 years).
Water Usage• Irrigation • Industry – coolant (power plant)• Domestic and Municipal• We currently use more than half of the
world’s reliable runoff of surface water and could be using 70-90% by 2025
• Irrigation = 70%; Industries = 20%; Cities and residences = 10%
• About 70% of the water is not returned to the sources
Restoration• Build huge aqueduct, or find other
sources of fresh water and protect it federally under endangered species act, etc.
Flooding • Heavy rainfall, rapid snowmelt, removal of
vegetation, and destruction of wetlands cause flooding.
• Floodplains, which usually include highly productive wetlands, help provide natural flood and erosion control, maintain high water quality, and recharge groundwater.
• To minimize floods, rivers have been narrowed with levees and walls, and dammed to store water.
Oxygen released by vegetation
Diverse Diverse ecological ecological habitathabitat
Evapotranspiration
Trees reduce soil erosion from heavy rain and wind
Agricultural land
Steady river flow
Leaf litter improves soil fertility
Tree roots stabilize soil and aid water flow
Vegetation releases water slowly and reduces flooding
Fig. 14-23b, p. 330
Tree plantation
Roads Roads destabilize destabilize hillsideshillsides
Evapotranspiration decreases
Ranching accelerates soil erosion by water and wind
Winds remove fragile topsoil
Agricultural land is flooded and silted up
Gullies and Gullies and landslideslandslides
Heavy rain leaches nutrients from soil and erodes topsoil
Silt from erosion blocks rivers and reservoirs and causes flooding downstream
Rapid runoff causes flooding
After Deforestation
Too Little Water• Drought • Desertification• Lake levels drop, recreation use drops,
fisheries drop, and salinization occurs • Ex. Soviet Union (Aral Sea); the inland sea
drained the river that fed into it.
• Water was diverted (irrigation) from the Aral Sea and its two feeder rivers • About 85% of the wetlands have been
eliminated and roughly 50% of the local bird and mammal species have disappeared.
• Since 1961, the sea’s salinity has tripled and the water has dropped by 22 meters most likely causing 20 of the 24 native fish species to go extinct.
Salinization of Irrigated Soil
• Water is poured onto soil and evaporates. Over time, as this is repeated, nothing will grow there anymore.
Saltwater Intrusion
• Miami encroaches on everglades • Drained for water and increased
development• People vs. wildlife
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