Chapter 11Water

Properties of water that are important to know for Environmental Science

Water is a polar molecule Surface tension Capillary action

Water has a high heat capacity Water is most dense at 4°C (ice floats) Water’s boiling point is 100°C and its freezing point is 0°C

condensation Light is absorbed by water

it can only penetrate to about 200 meters Absorption of light heats up the water

Water is a universal solvent Dissolved oxygen, CO2

and other gases – amount increases as water temp increases Dissolved nutrients Dissolved pollutants and toxins Conductivity – measures amount of dissolved solids in water; ocean water has high conductivity due to

all the salt Water is a powerful agent of erosion – wears away rocks, also carries sediment as long as it is flowing, when

it slows down, it deposits the sediment• Water evaporates as pure H2O, but water in the atmosphere can pick up pollutants (water cycle purifies water,

but it can then become polluted by air pollutants)• Water (like all things on earth) is subject to gravity and flows downhill• Water can carry diseases• Water is purified, filtered as it passes through sand, charcoal, gravel, rocks, even soil• All living things on earth require water to survive

World Water Distribution

Total:97% salt water3% freshwater

Freshwater:70% glaciers29% aquifers1% lakes, rivers, streams

Section 3 – The Hydrosphere and Biosphere

Hydrosphere – all the water on or near the Earth’s surface

Steps of the water cycle

Water (or hydrologic) cycle – continuous movement of water into the air, onto land, and then back to water sources

1. Evaporation – liquid water is heated by the sun and then rises into the atmosphere (steam or humidity)

2. Condensation – water vapor forms water droplets on dust particles and form clouds or fog

3. Precipitation – large droplets fall from clouds in the form of rain, snow, sleet, or hail

Water (or Hydrologic) Cycle

Processes in the water cycle:1. Evaporation: liquid gas with addition of heat2. Condensation: gas liquid when cools down3. Precipitation: small drops collect into larger drops and fall to earth4. Transpiration: water moves from plant leaves into air5. Infiltration: water soaks into the ground, may go into groundwater

Locate the water storage locations on this diagram…• Freshwater storage• Water storage in oceans• Ground water storage

Water (or Hydrologic) Cycle

Earth’s Oceans

The Earth’s oceans cover over 70% of the Earth’s surface

Ocean water –characterized by relatively high salt content

Salinity – the amount and concentration of salt in ocean water

Ocean Currents

The ocean has movements of water similar to streams called currents. There are 2 different types of ocean currents.

1. Surface currents – occur near the surface of the ocean; they are driven by the wind

2. Deep currents – occur near the floor of the ocean; they are very slow moving and COLD

Surface ocean currents

A Global Temperature Regulator

One of the most important functions of the ocean is to absorb and store energy from the sun

Ocean currents redistribute heat around the globe

This function is what regulates the temperature of the Earth

Fresh WaterIs different from oceans because it is not salineOnly accounts for about 3% of all water on earthInclude all of these:

Icecaps and glaciers Rivers, lakes and wetlands Groundwater Aquifers

Surface Water

Lakes, rivers, streams, wetlands, estuaries

Watershed: the area of land that is drained by a river

River system: the flowing network of water draining a river basin

Groundwater

Groundwater: water that is beneath the earth’s surface

Water table: the upper level of water underground

Aquifer: underground formation that contains groundwater

Aquifers

Most are made of materials like rock, sand, gravel with spaces in which the water can be held like a sponge (see pgs. 274-275)

Water can be tapped from aquifers for use by people; if used too much and too quickly, it can go dry (Ogallala Aquifer case study, pgs. 272-273)

Aquifers Aquifers can be refilled as

water percolates down through the recharge zone, may take a long time

Porosity – amount of space between particles of the rock

Permeability – ability of the rock or soil to allow water to flow through it

Pollution can enter the groundwater through the recharge zone (think about Silent Spring) – it can then travel to other places through the underground water system, even showing up years later

Water as a Resource Do you think water is a renewable

resource? It is a renewable resource because it

can be replenished by nature (water cycle)

However, if it is made unusable by pollution faster than nature can replenish it, then it is considered nonrenewable

Potable Water – water that is drinkable, usually following treatment.

Biosphere

The Biosphere – the narrow layer around Earth’s surface in which life can exist; from about 11km into the ocean, all of the earth’s surface and up to 9km in the atmosphere

Requirements for life as we know it: Liquid water Temps between 10°C and 40°C Source of energy (sunlight in most

cases, but chemical energy is another source)

Materials needed for growth must be cycled, through air, water, earth and organisms

Is earth a closed or open system?

Closed system: Matter cannot enter Energy does enter

Open system: Matter can enter Energy can enter

Which type of system is this?

The Six Kingdoms of Living Things