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ENVIRONMENTAL CHEMISTRY
Final Exam Review
KEY CONCEPTS
Chemicals essential to
life
 Substrates and
nutrients
 Air and water quality
 Organic and inorganic
material
 Acids and bases
 Ingestion and
absorption of
materials

Concentration and
dispersal
 Evidence of toxicity
 Stability and
biodegradability
 Uncertainties in
environmental
monitoring and in
assessing toxicity and
risk

NUTRIENTS
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Nutrients are compounds or elements that are
essential for production of the organic matter
that makes up organisms.
The four key nutrient categories are
carbohydrates, proteins, lipids (fats) and
minerals.
NUTRIENTS

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Organic nutrients are carbon-based compounds
such as carbohydrates, proteins, lipids, and
vitamins, which are produced by green plants
and modified by animals.
Inorganic nutrients – the minerals – are divided
into macrominerals and trace elements,
depending on how much is needed for normal
health.
UPTAKE OF NUTRIENTS

Consumers rely on the ingestion of other
organisms in order to satisfy their energy and
nutrient requirements.


Ingestion: the process of taking in the nutrients
needed for survival
A substrate is a material on which an organism
moves or lives. Some organisms attach
themselves to the substrate, while others obtain
their nutrients from their substrate.
FERTILIZERS


Artificial fertilizers greatly increase the amount
and types of plant crops that can be grown for
human consumption, but also require large
amounts of fresh water.
Agriculture influences the environment by
effectively decreasing biodiversity.
PESTICIDES

The use of chemical poisons and toxins to control
pests is widespread and although they are
effective in reducing disease-causing organisms,
they should be carefully controlled and regulated.

herbicide: a chemical used to control weeds

insecticide: a chemical used to control insects

fungicide: a chemical used to control fungus
ACIDS, BASES, AND THE PH SCALE

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The pH scale ranges from 0 to 14, and is used to
compare substances based on their acidic and
basic properties.
Acidic substances taste sour, conduct electricity,
and have a pH of less than 7.
Basic substances taste bitter, feel slippery,
conduct electricity, and have a pH greater than 7.
Neutral substances have a pH of 7.
PH INDICATORS



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pH indicators use color changes to help identify
substances.
Litmus paper turns red in the presence of an acid,
and blue in the presence of a base.
pH paper turns a different color for each pH value.
Other common pH indicators include red cabbage
juice, phenolphthalein, bromothymol blue,
bromocresol green, and methyl red.
EMISSIONS FROM INDUSTRY


Fossil fuel combustion results in the emission of
nitrogen, sulfur, and carbon oxides that react
with moisture in the atmosphere to form acidic
compounds.
Acid precipitation results in the leaching of
minerals from soils, and damage to living
organisms.
REDUCING EMISSIONS FROM INDUSTRY


Acid-base neutralization reactions between
minerals, such as limestone (calcium carbonate)
and acidified waters in lakes and streams, can
lead to more neutral pH water.
Sulfur scrubbers and catalytic converters work to
reduce the amount of nitrogen, sulfur, and carbon
oxides that are released, in order to prevent acid
precipitation from ever forming.
TOXICITY



Acute toxicity: the ability of a chemical to cause
harm with only one exposure
Chronic toxicity: the ability of a chemical to
cause harm to an organism only after the
chemical accumulates to a specific level after
many exposures over time
Since different organisms respond to toxic
chemicals in different ways, toxicity is commonly
measured by the LD50 – the dose needed to kill
50 percent of the population that it is applied to.
POLLUTION


The amount or dose of a pollutant that will cause
harm is established by observing the effects of
the pollutant on living organisms.
Concentration is usually expressed in parts per
million (ppm) or parts per billion (ppb)
ENVIRONMENTAL MONITORING


The monitoring of the levels of pollutants in any
ecosystem requires knowledge of how to detect
those pollutants or their effects, either by
chemical testing or direct observation of
biological organisms.
Biological indicators are organisms whose
presence or absence gives clues as to the amount
of pollution affecting any ecosystem.

Ex. The presence of macroinvertebrates in a stream
DISPERSAL OF POLLUTANTS

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The dispersal of atmospheric pollutants is
affected by global wind patterns. Pollutants may
be carried great distances before their effects are
felt.
Pollutants can also travel through water
systems.
Soluble pollutants can travel large distances
through bodies of water. Insoluble pollutants
can contaminate a localized region for long
periods of time.
BIODEGRADATION



Biodegradable wastes are those wastes that can
be broken down by the action of living organisms.
The rate of biodegradability is determined by the
chemical structure of the waste material.
persistent pollutant: wastes that accumulate
in the environment and break down very slowly,
if at all
non-persistent pollutant: wastes that can be
broken down into simple non-polluting
compounds by naturally occurring chemical
reactions or bacterial action
EXPERIMENTAL VARIABLES

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Control – any element of an experiment that is
unchanged or consistent throughout the trials
Manipulated – the element of an experiment that
is changed throughout the trials. This is what
the experiment is testing for , and is related to
the experimental question or purpose.
Responding – the result of an experiment, based
on observation. This should provide an answer to
the experiment question.
WHAT TO EXPECT ON THE PAT
From this unit:
 10 multiple choice questions
 1 numerical response question
4 “knowledge” questions
 7 “skills” questions

EXAMPLES OF KNOWLEDGE QUESTIONS
The presence of a
species of large trout in
a particular lake
indicates a
A. High dissolved
oxygen concentration
B. Low dissolved
oxygen concentration
C. High water
temperature
D. Low water pH
Which of the following roles
is played by carbohydrates
in human nutrition?
A. Act as an energy source
B. Assist enzyme function
C. Storage form of unused
chemical energy
D. Structural component of
cells in the body
EXAMPLES OF SKILLS QUESTIONS
Bromothymol blue is an
indicator that changes colour
at different pH levels.
Bromothymol blue will
appear yellow when mixed
with
A.
Lemon juice
B.
Baking soda
C.
Drain cleaner
D.
Distilled water
The carcass of a whooping crane
was found along the shore of a
lake. It was examined, and high
levels of pesticide were found in its
tissues.
Fish of various species were then
collected from the lake, and they
were found to have moderate levels
of pesticide in their tissues.
Which of the following statements
best explains the high levels of
pesticide in the whooping crane?
A.
The whooping crane’s skin
absorbed the pesticide
B.
The whooping crane swam in
contaminated lake water
C.
The whooping crane fed on
pesticide-treated grass near
the lake
D.
The whooping crane’s primary
food source was the fish from
the lake