Unit C Section 3.1

Question 1

the three stages of transport of substances in the air:

Answer 1

1. Release of the chemical at the source
2. Dispersion of the chemical in the atmosphere (the chemicals scatter in various directions)
3. Deposition of the chemical in soil or water

Question 2

What are the factors that determine the direction and distance that airborne chemicals travel?

Answer 2

• pollutant’s properties,
• the wind speed,
• the direction of the prevailing winds.

EX. in Alberta, prevailing winds are from the west, so airborne substances are carried eastward.

Question 3

What factors affect the distribution of airborne chemicals?

Answer 3

• wind (distribution of airborne pollutants may be limited by lack of wind)
• Precipitation (An airborne pollutant will be deposited closer to its source if it is carried to the ground by rain or snow.)

Question 4

is it possible to find the source of airborne pollutants?

Answer 4

• The source of a chemical that has traveled thousands of kilometers is usually impossible to identify.
• Often chemicals travel across borders, so the deposition of airborne pollutants is an international problem.

Question 5

First zone for the water that soaks into the soil:

Answer 5

• Water that soaks into soil moves first into a zone near the surface.
• Here the spaces between the soil grains contain both air and water.

Question 6

Second zone for the water that soaks into the soil:

Answer 6

• As the water moves deeper, it enters the next zone where all the spaces are filled with water
• This water is called groundwater

Question 7

What is groundwater:

Answer 7

all the spaces in the soil are filled with water.

• Groundwater can move sideways, up, and down.
• It can move as slowly as 1 m per year or as quickly as 1 m per day

Question 8

What is a water table:

Answer 8

The top of the groundwater zone is called the water table

Question 9

Why is groundwater not always safe for drinking, agricultural purposes, or industrial use?

Answer 9

• Because of groundwater’s slow movement, contaminants such as lead cannot be quickly dispersed.
• They may become concentrated over time.

Question 10

The factor that affects the movement of groundwater:

Answer 10

-number and connection of pores in the soil

Question 11

What are pores?

Answer 11

Pores are the tiny spaces between soil grains.

Question 12

What is permeable soil?

Answer 12

• A permeable soil is one with connected pores.
• Lets water move through easily
• Soil grain are not packed too tightly

(Sand)

Question 13

How are pollutants transported in permeable soil?

Answer 13

-Pollutants will be transported farther by groundwater that flows through permeable soils.

Question 14

The substances that contaminate groundwater occur:
(Contaminants)

Answer 14

1.Minerals in rocks and soil-Iron, calcium, selenium
2.Organic substances occurring naturally or produced by humans-Pesticides, solvents
3.Substances leached from landfill sites and mine waste-Heavy metals
4.Substances that leak from underground storage tanks and pipelines-Gasoline, natural gas, oil
5.Inorganic substances-Salt,fertilizers, acidic deposition
6.Micro-organisms from improperly designed or
maintained septic tanks and sewage treatment ponds,
and improper storage and disposal of livestock wastes
7.Household chemicals-Nitrates, phosphorus compounds, detergents, chlorine compounds

Question 15

Sources that hazardous chemicals can enter surface water systems:

Answer 15

air,
groundwater,
runoff from agricultural fields and industrial sites, outflow from storm sewers
sewage treatment plants.

Question 16

Why can chemicals in surface water systems be a problem?

Answer 16

-Chemicals from these sources may not be a
the problem if their concentrations are very low.
If they are dispersed or carried away.
-they may become a problem if the chemicals do not disperse, and the concentrations increase locally

Question 17

The landing of water can do four things:

Answer 17

• some evaporate
• some soaks into the soil and is taken up by plants
• some runs onto the street or into a stream
• some soaks through the soil and moves downward.

Question 18

What is leachate?

Answer 18

As this water moves in the soil, it dissolves substances in the soil and carries them along. Such a liquid is called leachate.

Question 19

What is impermeable soil?

Answer 19

• the soil in which water does not moves more easily
• There are no connected pores.
• soil grains are packed too closely

(clay)

Question 20

What is the purpose of clay liners in sanitary landfills:

Answer 20

The clay prevents leachate containing harmful chemicals from moving into the soil and contaminating groundwater

Question 21

What can slow down the movement of the chemicals in leachate?

Answer 21

• Organic material such as decayed leaves
• This can slow down the movement because they can be absorbed by the organic material.

-Sometimes the chemicals become attached to the soil particles, and their movement is slowed or stopped.

Question 22

How can hazardous substances be changed by chemical reactions in the soil?

Answer 22

For example, acids can be neutralized by substances

such as calcium carbonate (limestone) in soil.