WaterWater

An Environmental PerspectiveAn Environmental Perspective

Why is water so important?Why is water so important?

• Water covers nearly 75% of the earthWater covers nearly 75% of the earth

• Less than 1% of this is accessibleLess than 1% of this is accessible

• 65- 70% of your body is water. 65- 70% of your body is water. Main organs Water content in %

Brain 75

Blood 92

Bone 44

Heart 75

Kidney 83

Liver 86

Lung 86

Muscle 75

Important Properties of Important Properties of WaterWater

Six reasons why water is the Six reasons why water is the wellspring of life! wellspring of life!

Strong interactive forces hold Strong interactive forces hold each water molecule to every each water molecule to every other water moleculeother water molecule• This is a force between This is a force between

molecules. molecules.

• This intermolecular force This intermolecular force is the strongest is the strongest intermolecular force. intermolecular force.

• It is called a hydrogen It is called a hydrogen bond but it is not truly a bond but it is not truly a bond. *bond. *

Wide temperature range for Wide temperature range for liquidliquid

• Because of the hydrogen bonding Because of the hydrogen bonding force, the molecules of water require force, the molecules of water require much more energy to heat them to a much more energy to heat them to a boiling point.boiling point.

• Compared to other liquids with this Compared to other liquids with this molar mass (mass of one mole of the molar mass (mass of one mole of the substance) the 100 degree C range substance) the 100 degree C range for the liquid is quite large. *for the liquid is quite large. *

Water can hold large amount Water can hold large amount of heat without change in of heat without change in temperaturetemperature• When you walk on a sandy beach on a hot, When you walk on a sandy beach on a hot,

summer day, which is hotter—the water or summer day, which is hotter—the water or the sand? the sand?

• Do both the water and sand receive the Do both the water and sand receive the same amount of heat from the sun? same amount of heat from the sun?

• Why is the water so much cooler? Why is the water so much cooler? • Water has a large specific heatWater has a large specific heat• Specific heat is the amount of energy it Specific heat is the amount of energy it

takes to heat one gram of a substance one takes to heat one gram of a substance one degree Celsius *degree Celsius *

Many compounds will dissolve Many compounds will dissolve in waterin water

• Water is a polar substance. This means that Water is a polar substance. This means that it will dissolve all other polar substances it will dissolve all other polar substances and the majority of ionic (metals bonded to and the majority of ionic (metals bonded to nonmetals like salts—NaCl)nonmetals like salts—NaCl)

• Nonpolar substances like oils, greases, and Nonpolar substances like oils, greases, and waxes will not dissolve in water but nearly waxes will not dissolve in water but nearly everything else will. everything else will.

• So many things dissolve in water that it has So many things dissolve in water that it has been dubbed the universal solvent *been dubbed the universal solvent *

Water has a high surface Water has a high surface tensiontension

• Have you ever filled a cup above full Have you ever filled a cup above full so that the water actually created an so that the water actually created an arch above the cup? How can water arch above the cup? How can water do this? do this?

• Water’s strong hydrogen bonding Water’s strong hydrogen bonding forces create a strong surface forces create a strong surface tension for water. *tension for water. *

Water expands when frozenWater expands when frozen

• Why do sealed containers that contain Why do sealed containers that contain water explode when frozen? water explode when frozen?

• Have you ever noticed that sealed Have you ever noticed that sealed containers that contain water that are containers that contain water that are intended to be frozen have less water and intended to be frozen have less water and room for expansion?room for expansion?

• This is due to the unique open structure This is due to the unique open structure that water forms when frozen. that water forms when frozen.

• This also allows ice to float in water. This also allows ice to float in water. • What would be the consequences What would be the consequences

environmentally if ice did not float? *environmentally if ice did not float? *

Supply, Renewal, and UseSupply, Renewal, and Use

Of water as a resource Of water as a resource

Surface WaterSurface Water

• Water that doesn’t go into the Water that doesn’t go into the ground nor evaporate* ground nor evaporate*

Watershed or Water BasinWatershed or Water Basin

• A place from which water flows intoA place from which water flows into

• Example: a river, stream, or reservoir Example: a river, stream, or reservoir

• What is your “watershed address”?* What is your “watershed address”?*

GroundwaterGroundwater

• Water from precipitation that goes Water from precipitation that goes into soil or rock *into soil or rock *

AquifersAquifers

• Large, open areas in rock that are Large, open areas in rock that are filled with waterfilled with water

• Many aquifers are tapped for wells. *Many aquifers are tapped for wells. *

Dissolved Oxygen (DO) Dissolved Oxygen (DO) contentcontent• Amount of dissolved oxygen in a Amount of dissolved oxygen in a

given volume of water at a particular given volume of water at a particular temperature and pressuretemperature and pressure

• The higher the amount of DO the The higher the amount of DO the more diversified the aquatic more diversified the aquatic community should becommunity should be

• Bottom dwelling organisms have Bottom dwelling organisms have very low need for oxygen. *very low need for oxygen. *

SalinitySalinity

• Amounts of various salts that have Amounts of various salts that have been dissolved in a given amount of been dissolved in a given amount of water *water *

The water cycleThe water cycle

The hydrological cycle*The hydrological cycle*

Steps of the Water Cycle Steps of the Water Cycle • Leave room beneath each of these to Leave room beneath each of these to

write a description which will appear write a description which will appear laterlater

• PrecipitationPrecipitation

• InfiltrationInfiltration

• PercolationPercolation

• Ocean StorageOcean Storage

• EvaporationEvaporation

• Transpiration*Transpiration*

Water Water

CycleCycle

The water cycle The water cycle • Precipitation—water from the clouds Precipitation—water from the clouds

or atmosphere to the lithosphere or atmosphere to the lithosphere (can be rain, fog, snow, sleet, ice, or (can be rain, fog, snow, sleet, ice, or hail)*hail)*

Infiltration Infiltration

• Infiltration—precipitation which is Infiltration—precipitation which is absorbed by the ground*absorbed by the ground*

PercolationPercolation

• Percolation—a process that filters Percolation—a process that filters and cleans the water naturally; this and cleans the water naturally; this could be water from precipitation or could be water from precipitation or bodies of water or run off*bodies of water or run off*

Water Cycle (cont.)Water Cycle (cont.)

• Ocean Storage—reservoir for water; Ocean Storage—reservoir for water; the water in this basin is undergoing the water in this basin is undergoing constant change in the water cycle* constant change in the water cycle*

EvaporationEvaporation

• Evaporation—water is evaporated Evaporation—water is evaporated from water storage areas*from water storage areas*

TranspirationTranspiration

• Transpiration—water is given off by Transpiration—water is given off by trees and green vegetation*trees and green vegetation*

The cycle begins againThe cycle begins again

• Evaporation and Transpiration give Evaporation and Transpiration give water back to the atmosphere where water back to the atmosphere where it condenses into clouds and then it condenses into clouds and then can return in the form of can return in the form of precipitation.*precipitation.*

Aquatic Life ZonesAquatic Life Zones

Factors Factors

Layers and Regions* Layers and Regions*

Two factors that define an Two factors that define an aquatic life zoneaquatic life zone

• 1. Salinity—salt water content1. Salinity—salt water content– Brackish Brackish – SaltwaterSaltwater– FreshwaterFreshwater2.2. Dissolved Oxygen Content Dissolved Oxygen Content

High amounts of DO mean that there would High amounts of DO mean that there would be a high amount of biodiversitybe a high amount of biodiversity

Low amounts of DO would usually mean a Low amounts of DO would usually mean a very restricting level of organisms could very restricting level of organisms could live there. *live there. *

Water Resource ProblemsWater Resource Problems

Freshwater Shortages*Freshwater Shortages*

Fun Facts about Water and Fun Facts about Water and PopulationPopulation

• Canada’s population is about 0.7% of Canada’s population is about 0.7% of the world’s population.the world’s population.

• Canada contains about 20% of the Canada contains about 20% of the world’s fresh water supply.world’s fresh water supply.

• China’s population is about 20% of China’s population is about 20% of the world’s population. the world’s population.

• China contains only about 7% of the China contains only about 7% of the world’s fresh water supply. *world’s fresh water supply. *

How are we running low on How are we running low on water with so many oceans? water with so many oceans?

Reasons for freshwater Reasons for freshwater shortagesshortages

• Dry climateDry climate

• Drought Drought

• Desiccation Desiccation

• Water Stress (poor use of water as a Water Stress (poor use of water as a resource)*resource)*

Solutions for Water Solutions for Water ShortagesShortages

How to avoid freshwater How to avoid freshwater shortages*shortages*

Solutions to freshwater Solutions to freshwater shortagesshortages

• Build dams and reservoirsBuild dams and reservoirs

• Bring in surface water from other Bring in surface water from other areasareas

• Withdraw ground waterWithdraw ground water

• Desalination—removal of salt from Desalination—removal of salt from saltwater or brackish watersaltwater or brackish water

• Improved water efficiency*Improved water efficiency*

Water PollutionWater Pollution

Where do you think this Where do you think this picture was taken? picture was taken?

Definition of water pollutionDefinition of water pollution

Classes of water pollution* Classes of water pollution*

Definition of Water PollutionDefinition of Water Pollution

• Any chemical, biological, or physical Any chemical, biological, or physical change in water quality that has a change in water quality that has a harmful effect on living organisms*harmful effect on living organisms*

Classes of Pollution Classes of Pollution

• Disease-Causing PollutionDisease-Causing Pollution

• Water borne diseases kill 10 million Water borne diseases kill 10 million annually.*annually.*

Cheapest way to clean the Cheapest way to clean the water—The Sodis Methodwater—The Sodis Method

• Plastic bottles!Plastic bottles!

1.1. Fill a plastic bottle with waterFill a plastic bottle with water

2.2. Shake the bottleShake the bottle

3.3. Put the water in direct sunlight (UV Put the water in direct sunlight (UV light) for 6 hours*light) for 6 hours*