Hydrosphere

Water

• substance made up of hydrogen and oxygen

• can take solid, liquid, and gaseous forms

• most abundant substance on earth

• about 71% of the earth’s surface is covered by water

• the total amount of water is constant, but what changes are its quality, distribution and availability

Important Property 1. Water is a solvent that is able to dissolve and transport ions and molecules

• water not only dissolves these substances, but also moves them around

• water helps living things get the nutrients they need and cleans things like our bodies, rivers, and oceans by carrying away substances that are dissolved in it

• BUT this ability of water to act as a solvent also means that it is easily polluted

Solvent

• something that can dissolve other substances

• water is a universal solvent

Ions

tiny pieces of substances that have an electric charge

Molecules

groups of atoms stuck together

Important Property 2. Water has a relatively high heat of vaporization

• amount of energy needed to convert a substance from liquid to vapor state

• plays an important role in global climate and weather patterns

High heat of vaporization

means high absorption of heat when it evaporates = cooler surroundings

Important Property 3. Water has a relatively high heat capacity

ability of a substance to absorb or release heat without a large temperature change

High heat capacity

can solve large amounts of heat

Important Property 4. Water is the only natural substance that expands when it freezes

• ice had lower density than liquid water

• since ice forms at the top first, life can still go on under water

Important Property 5.

Water has the ability to solvate the hydrogen ion and dissociate into H+ and OH-

Acids

• part of pH

• release hydrogen ions (H+) when they are in water

• high hydrogen ions = stronger acid

Bases

• part of pH

• release hydroxide ions (OH-) when they are in water

• high hydroxide ions = stronger base

More rain

means more flow in rivers, more groundwater

Hydrologic Cycle

Runoff

• rain that does not soak into the ground

• carries soil, pollutants, and other materials from the land into our rivers, lakes, and bays

Residence Time

amount of time that a water molecule stays within a particular hydrologic cycle

Average residence time of water in the water cycle

More mobility

means less/shorter residence time

Water locked in solid phase

means longest residence time

Bigger reservoir

higher residence time

Lower residence time

means pollutants can be flushed out rapidly

More residence time

means harder to clean

Consumptive Use

water quality is degraded from its use

Non-Consumptive Use

water quality is unchanged, unless pollution occurs during use

Point Source

• type of surface water pollution

• single, identifiable source of pollution

• ex: pipe or drain from a factory or sewage treatment plant

Non-Point Source

• type of surface water pollution

• pollution cannot be traced to a single point of origin

• ex: agricultural runoff which can accumulate from multiple source