Water UnitThe Hydrosphere and Water Quality

Biological Indicators

Cohesion

Adhesion

Solvent

Capillary Action

Specific Heat

Density

Buoyant or Buoyancy

Hydrosphere

Evaporation

Condensation

Precipitation

Collection

Water Quality

Temperature

Thermal Pollution

pH

Turbidity

Key Vocabulary

Most of the Earth's water is found in the oceans. Water is everywhere on Earth. Around seventy percent (70%) of the surface of the Earth is covered by water. If you were an alien visiting the planet, you would see a giant blue sphere from space (especially on the Pacific Ocean side). Not only is water everywhere, but all life depends on water from the tiniest bacteria and the largest dinosaurs have all needed water.

Water, Water, Everywhere

What is the hydrosphere?

What is the Hydrosphere?• The water on Earth makes up the Hydrosphere.• The Hydrosphere includes oceans, rivers, streams, lakes and other bodies of

water.• The Hydrosphere also includes water frozen in the polar ice caps and water vapors

in the atmosphere

Because water is so important, it makes up an entire section of the earth sciences. You will probably hear the term "hydro" many times.

The prefix “hydro” has origins in ancient Greek. You will learn about hydrologists that study water and the way it is used and circulated across the planet. Hydrology is the study of water. That water may be at the bottom of the ocean or in clouds found in the atmosphere.

Anything related to water is a part of the hydrosphere.

Movement of WaterThe Water Cycle

What is the Water Cycle?The water cycle is a constant recycling process of Earth’s water. It consist of evaporation, condensation, precipitation, and collection.

Evaporation: The phase change that occurs when liquid water acquires enough heat energy to form water vapor.

Example: The sun heats water in rivers, lakes or oceans and turns it into vapor or steam.

Condensation: The phase change that occurs when water vapor loses heat energy to form liquid water. It is generally brought about by a fall in air temperature.

Example: Water vapors in the air get cold and change back into liquid forming clouds.

Water Cycle Precipitation: Literally “to fall out of.” In nature, precipitation may take the form of rain, snow, hail, and sleet. Frost is not precipitation, but occurs when water vapor changes directly from a gas to a solid.

Example: Occurs when water condenses and the clouds can not hold it anymore. The water falls back to Earth in the form of rain, hail or snow.

Collection: When water (in any form) returns back to Earth as precipitation. it may fall back (collect) into the rivers, lakes, oceans or may end up on land.

Water quality describes the condition of the water, including chemical, physical, and biological characteristics, usually with respect to its suitability for a particular purpose such as drinking, swimming, and sustaining life.

Water Quality

What affects our quality of water?

TemperaturepHNitrates & PhosphorusTurbidityBiological Indicators

If all life depends on water…..what do we need to know about it?

Temperature

• Temperature has a direct effect on plant and animal life.• Temperature affects the rate of photosynthesis and respiration in algae and

aquatic plants.• The sensitivity of organisms to toxic wastes, parasites and diseases.

A measure of molecular motion, generallyusing a Fahrenheit (F) or Celsius (C) scale.

Examples: -Storm water running off of warm streets and parking lots -Construction along riverbanks removing shading trees

increases amount of sunlight. -Soil erosion increases the amount of solids in water which absorbs more of the sun’s heat.

Thermal Pollution:

Thermal pollution is caused by adding relatively warm water to a cool body of water

Example: Industries, such as nuclear power plants or paper mills use

water to cool machinery or process materials. If warm water is released back into a stream or river it can increase water temperature.

pH

• pH- measures the concentration of hydrogen ions in a substance. • Information is used to determine if a substance is an acid, base or neutral.• pH is very important because it affects the function of all the enzymes, hormones

and other proteins.

A way of describing the acidic or basic strength of a solution. The pH value of a solution is a number on a scale from 0 to 14.

A pH value of 0–1 indicates a strong acid. A pH value of 12–14 indicates a strong base. A pH value of 7 indicates a neutral solution.

pH

• pH influences the metabolism, growth and development of aquatic organisms.

• Acid Neutral Base 0----------------------7------------------14Distilled water 7Ocean Water 7.8Natural Water 6.5-8.5

pH Scale

Human impact on pH

• Last 150 years the burning of fossil fuels has increased the amount of nitrogen oxide and sulfur dioxide released into the atmosphere.

• The two combine with moisture in the air and falls as acid rain.• Acid rain is responsible for many water sources becoming acidic.

Human activity causes of pH fluctuations are usually related to pollution. Acid rain is one of the best known examples of human influence on the pH of water. Any form of precipitation with a pH level less than 5.0 is known as acid rain.

This precipitation comes from the reaction of water with nitrogen oxides, sulfur oxides and other acidic compounds, lowering its already slightly acidic pH. These emissions usually come from mining and smelting operations or fossil fuel combustion (coal burning and automobiles). Extremely high levels of CO2 can also further decrease the pH of rain.

Nitrates (NO3)Nitrogen is an element needed by all living plants and animals to build proteins

• Aquatic plants take in nitrogen from their roots. Aquatic animals get nitrogen by eating aquatic plants.

• A certain level of nitrates in water is good, however, an over abundance can be devastating to an ecosystem.

Sewage ( human and animal waste) and fertilizer are the primary source of adding nitrates to water. Sewage may enter from septic tanks, sewage treatment plants and animal waste farms.

Best Management Practices (BMP) is a concept farmers have to practice in order to keep fertilizers and animal sewage out of water.

Phosphorus• Phosphorus is an element essential for living organisms. Plant growth is limited by

the amount of phosphorus

• Increase phosphorus causes an increase in algae growth.

• Cultural Eutrophication:humans cause a level of increase nutrients in the water.

Turbidity

• The turbidity is greater when water is murkier.• Turbidity increases as the suspended solids in water increases and keeps sunlight

from passing through.• Clay, silt, plankton, industrial waste and sewage are things that increase the

turbidity or cloudy appearance.

Turbidity is the measure of the clarity or clearness of water

Humans affect turbidity by dumping industrial wastes and sewage into our waters. Suspended solids from wastes can clog fish gills and smother fish eggs.

Biological Indicators

Natural population of fish, insects , algae and plants are good biological indicators. The present or absences of these organism may suggest the condition of the water.

Living organism that help scientist determine the health of water resources

Water is in the air, on the land, between the rocks, and in every living thing. Water, in its purest form, is the compound H2O. There are two hydrogen (H) atoms bonded to one oxygen (O) atom. Generally, you won’t find pure water. There are usually other compounds, ions, or particles mixed with water. While water may move and carry other substances with it, you need to remember that the small water molecules are the things that make life on Earth possible.

Molecular Structure of Water

The structure of the water molecule allows this substance to have special properties.

Chemical formula for water is H20.

This means: There are two hydrogen atoms and one oxygen atom

* Water molecule has a “Y” Shape

*Hydrogen carries a “+” positive charge

* Oxygen carries a “-” negative charge

Since a water molecule has opposite charges it is known as a Polar Molecule.

Properties of Water

Just so you’ll know for later

The difference between a compound and a molecule is a molecule is formed when two or more atoms join together chemically.

A compound is a molecule that contains at least two different elements.

All compounds are molecules but not all molecules are compounds.

The image to the left shows a simple diagram of water molecules. Copy the image in your science notebook. Be sure that you indicate the positive (+) and negative (-) of each element.

• Strong molecular bonds form between positively and negatively charged poles.• Opposite ends of adjacent water molecules are drawn together.

Properties of Water

Cohesion and Adhesion

Cohesion is the attractive force between water molecules.

Example: Watching raindrops slide down a windowpane. The drops are drawn towards each other like magnets combining to form a larger raindrop.

The polarity of water causes it to bond with other positively and negatively charged particles.Example: Water will adhere, or stick to the fibers of a paper towel.

Properties of Water

Adhesion

Adhesion is when a molecules of water is attracted to other substances.

A solvent is a substance in which some other substance, called a solute, can dissolve to form a solution. Both the solvent and the solute can be solid, liquid, or gas, but liquid solvents and liquid or solid solutes are the most common and useful

Solvents

Universal SolventLiquid water is often called the “Universal Solvent” because it is able to dissolve more substances than any other liquid on Earth

•Water’s unique ability to dissolve many substances is due to its polar nature•Both the positive and negative end of the molecule can bond with another molecule that has the opposite charge.

Example: Table Salt:When Sodium (Na+) and Chlorine (Cl-) are added to water; the negatively charged oxygen atoms from the water surrounds the

positively charged sodium atoms. The hydrogen bonds with chlorine to create Salt Water .

With out this property, marine life could not exist.

Capillary ActionCapillary action is the process that moves water through narrow porous (passages

where water can move through) spaces.

This property makes it possible for water to move upward against gravity.

Example: Plants use capillary action to transfer water from soil through root

systems and leaves.

Specific HeatIs the amount of heat needed to raise the temperature of one gram of a substance by one degree Celsius.

The unit to measure heat energy in this case is the Calorie (cal)

For water, the specific heat is 1cal/g Celsius

The high specific heat of water gives it a high heat capacity. This mean that water is capable of absorbing a great deal of energy.

Example:This is why it takes a longer time to heat up a pot of water than it does to heat the metal coils on a stove.

DensityDensity is measure of the mass of a substance contained in a given volume.

Example: A wooden block and an iron block that are the same size; the wooden block would weigh less or be less dense.

Buoyant or BuoyancyBuoyant or Buoyancy refers to a a material that floats

Example: Frozen water is less dense than liquid water. That is why ice floats or is buoyant

Example: Cold water is denser than warmer water. This impacts our global

ocean circulation.

Cold dense, polar water sinks and warm tropical currents are able to move above them.