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