The HydrosphereUnit 9, Lesson 9.3

By Margielene D. Judan

Lesson Outline• The Hydrosphere• Water or Hydrologic Cycle (Review)• The Earth’s Oceans• Water Currents• Aquatic Organisms• Water Systems• The Underground Water System• Water Pollution

The Hydrosphere• Liquid portion of

the earth• All bodies of water

on the surface and under the earth’s surface

Water• One of the most important

substances known to man without which life would not be possible

• Comprises 3/4 of the Earth’s surface

• Approximately 2/3 of the human body weight

• Freshwater – 3% (The majority of the world’s freshwater is locked in the Antarctic ice cap)

• Saline water – 97%

Water• The only substance

on Earth that exists in large amounts in all three physical states:

• solid (ice caps) • liquid (oceans,

rivers and seas) • gas (steam from

geysers and hot springs)

Water Cycle Steps

1. Evaporation – liquid to gas2. Condensation – gas to liquid 3. Precipitation – water falls back to the ground either

as rain, snow, or hail

These three are the main processes of the water cycle

(Review from Lesson 5.6)

Water Cycle Steps

4. Surface Runoff – much of the water that return to Earth as precipitation runs off the surface of the land, and flows down hill into streams, rivers, ponds, and lakes. Small streams flow into larger streams, then into rivers, and eventually the water flows into the ocean.

Surface runoff is an important part of the water cycle because, through surface runoff, much of the water returns again to the oceans, where a great deal of evaporation occurs 

(Review from Lesson 5.6)

Water Cycle Steps

5. Infiltration – process where rain water soaks into the ground, through the soil and underlying rock layers, Some of this water ultimately returns to the surface at springs or in low spots downhill. Some of the water remains underground and is called groundwater. As the water infiltrates through the soil and rock layers, many of the impurities in the water are filtered out. This filtering process helps clean the water. 

(Review from Lesson 5.6)

Water Cycle Steps

6. Transpiration – process where plants remove water through its stomata in the leaves. This is the process of evaporation in plants (also called evapotranspiration).

(Review from Lesson 5.6)

The Earth’s Oceans• 71% of the earth’s surface• 5 oceans (largest to smallest)

1. Pacific Ocean – contains Marianas trench (deepest part in the world)

2. Atlantic Ocean – most travelled ocean

3. Indian Ocean 4. Antarctic Ocean5. Arctic Ocean

Characteristics of Ocean Water

1. Salty2. Denser than pure water3. Temperature of oceans vary with location4. Dissolved gases are important in maintaining

life activities of marine organisms (CO2 – 60 times greater in marine waters than in atmosphere)

Salinity• Measurement of the amount of salt dissolved in water

• NaCl – most common salt• 96.5% water and 3.5% salt• Salinity is higher in summers due to excessive evaporation of water

• Salinity is higher near the poles due to snow and glacier formation

• Salinity is lower in the surface of a body of water

Reading while floating effortlessly in the Dead Sea, the densest and saltiest sea in the world.

2 Main Factors That Affect Density of Ocean Water

• Temperature (inversely proportional to density)• Salinity (directly proportional to density)

Water Currents• Motions of the bodies of water, visible or invisible• Affected by: temperature, salinity and wind

• Warm water is less dense – move upward the surface

• Colder water is denser – sinks at bottom• Saltwater is denser than freshwater – sinks at bottom

• Freshwater – move upward the surface

Water Currents• Wind circulates nutrients from bottom of the oceans to the surface through currents

• Increases growth of phytoplanktons (aquatic producers) due to uptake of nutrients

Aquatic Organisms• Planktons• Nektons• Benthos

Planktons• Microscopic• Floats on surface• Photosynthetic• Zooplanktons – small aquatic animals that feed on phytoplankton

Phytoplanktons

Zooplanktons

Nektons• Larger swimming species

• Ex. fish, turtles, sharks, whales, etc.

Benthos• Live at the bottomlike plants rooted at the bottom of the soil

• Ex. starfish, sea urchin, sponge

Water Systems• Lotic – flowing water• Lentic – still water• Underground Water System

Lotic Water System (flowing)Examples:• Stream• Rivers• Waterfall • Creeks• Brooks• Rivulets

Lentic Water System (still water)Examples:• Lakes• Ponds• Swamps

Examples of Water Systems in PH• Cagayan River – longest river in the Philippines• Ma. Cristina Falls – generates hydroelectric power in Mindanao

• Pagsanjan Falls – tourist attraction in Laguna• Taal Lake – houses Taal Volcano; home of tawilis and Hydrophis semperi (world’s rarest snake)

• Lake Caliraya – man-made lake in Laguna• Laguna de Bay – largest lake in the Philippines

Underground Water System

Underground Water System• Rainwater that falls to ground may:1. Run off and reach a body of water2. Infiltrate soil and stored there for a long time• Determined by the characteristic of the ground

Underground Water System• Case 1: Ground is hard and smooth• Result: run-off

• Runoff – water that continues to flow and does not soak into the ground

Underground Water System• Case 2: Rain is heavy, slow• Result: infiltration

• Infiltration – process where rain water soaks into the ground, through the soil and underlying rock layers. Filters the water passing

Underground Water System• Case 3: Rain is heavy, fast, and hard driving• Result: run-off

• The water cannot infiltrate even the rain is heavy because it runs so fast and doesn’t have time to soak into the ground

Underground Water System• Case 3: Rain is light, slow• Result: infiltration

Underground Water System• Case 4: Land is steep (highly contoured/sloped)

• Result: run-off

Underground Water System• Case 4: Land is flat• Result: infiltration

Watershed• Land area where all the waters coming from various sources drain off

• Ex. Angat, Ambuklao, Magat, Pantabangan

Effects of Runoff Water and Infiltration

• Transport of nutrients• Eutrophication – overfertilization of water

*Plant roots soak up and hold water, preventing accidents like landslides

Ground Water• About 20% of world’s freshwater supply• Saturates a layer beneath the ground called the aquifer

• is the water present beneath Earth's surface in soil pore spaces and in the fractures of rock formations 

Aquifer• Underground layer of

permeable rock, sediment, or soil that yields water

• Source of pure water • The process of infiltration filters the water free from sediments and harmful microorganisms

• Not a lake or river underground

Water Table• Top layer of the aquifer

saturated with water• Follows the form of the

above ground topography

• Rises in wet years and falls in dry years

• Water flowing into land areas covered with soil and trees refills the aquifer

Artesian Well and Pumping Well• Water from the aquifer is pumped out by drilling a well below the water table

Water Pollution• Any physical,

chemical, and biological change in water quality that adversely affects living organisms

• Makes water unsuitable for desired purpose

Water Pollution• In the Philippines, according to the Department of Environment and Natural Resource (DENR), not even one of the 158 rivers is safe for drinking.

• 50/451 rivers in PH are considered biologically dead (ex. Pasig River)

Sources of Water Pollution• Domestic wastes• Agricultural wastes• Industrial wastes and activities• Litter• Petroleum spills

Effects of Water Pollution1. Biological effects • Biological Oxygen demand • Eutrophication • Bacterial growth 2. Chemical effects • Toxic substances • Radioactive substances 3. Physical effects • Dissolved solids 4. Aesthetic effects • Sedimentation

Eutrophication• Overfertilization of water with nutrients that results in oxygen depletion

• Nutrients are primarily nitrogen and phosphorus-rich compounds

Stages of Eutrophication1. Oligotrophic stage• Early stages • Nutrient-poor but oxygen-rich

• Waters are clear, cold and support little aquatic life

• Abundant growth of benthic plants

Stages of Eutrophication2. Mesotrophic stage• Addition of more nutrients • Increase in primary producers (plankton and algae) which in turn can support more and different consumer organisms

• Reduction of dissolved oxygen

Stages of Eutrophication3. Eutrophic stage• Well–fed stage • Excess organic matter

accumulates at the bottom• Rapid increase in

phytoplankton’s growth in the surface (algal bloom)

• Depleted oxygen• Diminished or no benthic plants

since phytoplankton dominates and blocks sunlight

Algal bloom is a sign of eutrophication.

Way to Improve Water Quality• Keep paved surfaces clean.• Turn your downspout onto your lawn.• Reduce use of fertilizers.• Wash vehicles on the lawn.• Capture and filter your runoff.

Assignment: Answer p. 313

Sources• Science Links 7