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Unit 3: Environmental Chemistry

Lesson 1: Nutrients

-Your body is made up of chemicals, which you obtain from the food you eat -The process of digestion breaks down the chemicals into small, soluble molecules, which pass through membranes into the blood vessels. -These NUTRIENTS circulate through your body to the cells where they are used for energy, growth, and cell repair.

- Nutrients can be divided into two major groups: ORGANIC and INORGANIC.

- Organic nutrients contain carbon and are classed as CARBOHYDRATES, PROTEINS, LIPIDS, and VITAMINS.

-Inorganic nutrients are referred to as MINERALS or ELEMENTS – iron, calcium, zinc etc.

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ORGANIC

MOLECULE

ROLE SOURCE

Carbohydrates Energy for

metabolism

Rice, grains,

potatoes, fruits

Proteins Structural

molecule for

body and helps

chemical

reactions

Meat, eggs,

legumes, nuts,

dairy products

Lipids Storage of

unused

chemical

energy

Vegetable oils,

nut oils, some

dairy products

- Green plants form many of the organic compounds.

- MICROMINERALS or TRACE ELEMENTS means the body needs less than 100 mg/day.

- Macromineral -means the body needs 100 mg/day

or more.

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- These minerals are essential components in ENZYMES, which are special protein molecules that regulate chemical reactions in living organisms. - Vitamins are large organic molecules that help the enzymes function and that the body CANNOT make itself

- Some of the Earth's elements are examples of chemicals the body needs and 16 of the naturally occurring elements occur in all living organisms.

- Green plants require 18 different elements.

- Humans require 22 different elements.

- In order to remain healthy, these elements must

be in balance.

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Lesson 2: Fertilizers

- Plants need three essential elements to grow and reproduce:

1. NITROGEN: for stem and leaf development 2. PHOSPHORUS: for seed germination, root

development 3. POTASSIUM: for flower and fruit

development

- On all commercially prepared fertilizer bags, these three elements, in the above order are shown by the use of a three-part number (21 - 7 – 7 – gives percentage of each)

- With the use of artificial fertilizers and other human activities, crop production has doubled worldwide since the 1950's. - Land barely suitable for farming can now be used with the use of fertilizers, irrigation, and the use of pesticides. - Pro: food production increases - Con: environmental impacts

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Pesticides

- Pesticides are used to control "pests". - There are three specific types of pest species:

1. HERBICIDES: control weeds.

2. INSECTICIDES: control insects.

3. FUNGICIDES: control fungus pests

- The chemical DDT is an example of an insecticide, which kills the insects it comes in contact with. Unfortunately it moves up through the food chain.

- BIOMAGNIFICATION: moving from producers to primary consumers to secondary consumers and accumulating in greater and greater amounts in the organisms higher in the food chain

- One major problem with pesticides is pesticide resistance - the ability of an organism to develop a resistance to a toxic chemical.

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Lesson 3: Acids & Bases

Acids

- Taste sour

- Soluble in water

- React with metals to produce hydrogen gas

Bases

- Taste bitter

- Soluble in water

- Feel slippery

- React with acids

Neutrals

- Neither acidic or basic

- Ex. water

Indicators and the pH scale

- An indicator is a chemical that changes a

different color in an acid vs a base

- Litmus paper is a common indicator

used in schools.

- It turns red in acids and blue in bases

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- pH is a scale used to indicate the strength

of the acid or base

- pH scale ranges from 0 – 14

- pH of 7 is neutral – pure water

- pH less than 7 – acid

- pH greater than 7 – base (see p. 198)

0 acid 7 base 14

- Other indicators include: phenolphthalein, bromothymol blue, and methyl orange.

Neutralization Reaction When an acid is mixed with a base, the products are water and a salt - this is called neutralization.

Ex. Stomach acid has a pH of 2. Antacids are mild bases that react with excess acid and neutralize it.

Acid + Base -----> Water + Salt

e.g.

Hydrochloric acid + sodium hydroxide ----> water + sodium chloride

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Lesson 4: Acid Rain

- Usual pH of rain is 5.6 - Acid rain has a pH lower than 5.6

(the lower the pH the more acidic) - Sulphur, nitrogen, and carbon oxides combine with water vapor in the air to produce acids.

SULPHUR DIOXIDE (S02)

- Clear, colorless, highly corrosive gas smells like rotten eggs - Coal contains more sulphur than oil and

much more than natural gas Sulphur + oxygen ---> sulphur dioxide

- Sulphur dioxide combines with water to

make acid rain (sulfuric acid).

NITROGEN DIOXIDE (N02)

- Yellowish, brown gas responsible for smog.

- Nitrogen oxide combines with water to produce acid

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rain (nitric acid)

HYDROCARBONS

Carbon and hydrogen compounds create carbonic acid

Carbon dioxide + water carbonic acid

Acid Rain Causes

- Changes in soil and water that reduce soil fertility.

- Leaching of toxic chemicals such as mercury from the soil

into water

- Corrosion of metal surfaces.

- Eats stone statues and limestone buildings.

Acid Shock

- Spring melting releases large amounts of acids into rivers,

lakes, etc. for a short period. Unfortunately females have

difficulty laying eggs in acidic water. Therefore, no young

are born and the fish population eventually dies out.

Controlling Acid Rain Effects

- To neutralize the acid in lakes calcium carbonate is added

- Limestone is a major source of calcium carbonate

- Limestone will neutralize acid rain - granite does not.

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- Areas where there is limestone have less destruction due to acid

rain.

- The process of adding calcium carbonate to the

environment is called LIMING or ACID-BASE

NEUTRALIZATION.

Controlling Emissions

CATALYTIC CONVERTERS

- Are devices, which remove oxides before they enter the air.

- Aids the formation of carbon dioxide and water from

hydrocarbons thus reducing the amount of carbon monoxide

and nitrogen oxides produced.

"SCRUBBERS"

- Are devices that industrial factories and power plants, that burn coal, use to remove oxides.

They use sorbents - substances that absorb or capture

oxides.

COBRA (Copper Oxide Bed Regenerable Application)

uses beads of aluminum oxide with copper to remove

sulphur dioxide gas - the beads can be reused.

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Lesson 5: Concentrations

POLLUTION is material or form of energy added to the environment that will cause harm to a living organism.

- The harm may not be immediate depending on concentration

- Concentration of a harmful substance is usually given in (ppm) parts per million, (ppm is the same as # of mg/kg).

Ex. There is 7 mg of cholesterol in 125 g of yogurt. What is the concentration of cholesterol in ppm. Answer: We know that 1ppm is equal to 1mg/kg. Therefore we have to change the mass of the yogurt to kg.

125 = 0.125 kg 1000 7 mg cholesterol = 56 mg/kg 0.125 kg yogurt

- Since mg/kg is equivalent to ppm, there is 56 ppm

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of cholesterol in yogurt.

- TOXICITY is the ability of a chemical to cause harm to an organism.

- ACUTE TOXICITY serious symptoms appear after only one exposure to chemical.

- CHRONIC TOXICITY symptoms appear when chemical accumulates to a specific level after many exposures over time (lead)

- It is not easy to establish the level at which a substance is toxic due to the differences in body mass, metabolism, and lifestyles.

- LETHAL DOSE 50 - refers to the dose of a chemical that will kill 50% of the population to which it is applied.

- Since not all individuals or species react the same to a particular chemical, establishing risk is often difficult.

- A dose that kills one may only cause mild discomfort in another

- Toxicity depends on how it enters the body

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- Published toxicity levels on humans are guesses based on assumptions - Every chemical has the potential to be harmful, depending on dose, our susceptibility, and how it reacts with other chemicals. The evaluation of risks and benefits of any chemical form the basis of how chemical use is regulated.

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Lesson 6: Monitoring Waste

- Waste can be divided into two categories:

1. NON-PERSISTENT or BIODEGRADABLE

- Waste that can be broken down into simple non-polluting compounds (fertilizers, food).

2. PERSISTENT or NON-BIODEGRADABLE

- Accumulate and break down very slowly or not at

all. The damage done by these pollutants is

irreversible (Pesticides, petroleum products).

WATER QUALITY

- Cloudy water or turbid contains un-dissolved solids suspended in it. Suspended solids block sunlight, which reduces the ability of plants and algae to carry on photosynthesis. Photosynthesis produces oxygen, so there will be insufficient oxygen for other organisms.

Measuring Phosphates and Nitrates - Excessive amounts may cause algae to form a

dense growth or "algal bloom". Once the excess phosphates and nitrates are used up the algae dies and the decomposers take over and reduce oxygen levels.

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Measuring Dissolved Oxygen - Measured in milligrams per liter (mg/L) or parts

per million (ppm). Most organisms need a minimum

of 5.0 mg/L of oxygen

- Amount of oxygen in water depends on 2 main

factors:

1. Abiotic Factors - Non-living parts of the environment including

temperature of water and whether it is calm or turbid.

2. Biotic Factors - Living parts of the environment

- Organisms such as fish, snails, bacteria and fungi use

oxygen in water. If there are a large amount of

biodegradable material the decomposers multiply and use

up the oxygen.

Biological Indicators

- Most species of organisms cannot live in polluted water,

but some species of worms and insect larvae (young) thrive

in polluted conditions. These organisms are referred to as

BIOLOGICAL INDICATORS.

- The most useful organisms for a biological indicator of

water quality are the MACRO-INVERTEBRATES -

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organisms visible to the unaided eye and have no backbone.

- A survey of the number and type of macro-invertebrates

found in a body of water can provide a general indication of

whether pollutants are present or not.

* Organisms that are representative of poor water

quality may be found in any type of water.

* Organisms representative of good water quality are

found only in water of good quality.

POINT SOURCE - specific location where pollutants enter the

environment - easy to monitor and control. Ex. Drainpipes,

smokestacks.

NON-POINT SOURCE - are often separated both in time and

location from the source - much harder to control because the

pollutants become highly dispersed as they travel. Ex. Feedlots,

construction sites, run off from fertilized fields.

Assignment 6: p. 235 # 1- 4 (copy questions)

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Lesson 7: Blowing in the Wind

Human beings produce over 1000 billion kg of solid waste every year, which must be removed and stored, but “Not In My Back Yard” In the past, natural sources such as forest fires and volcanic eruptions introduced the majority of pollutants into the air. While this is still true for most of the southern hemisphere, human activities are the biggest source in the northern hemisphere.

Due to the wind patterns in the northern hemisphere, airborne particles and gas pollutants tend to concentrate at higher latitudes and are eventually washed out of the atmosphere by rain and snow.

Chlorofluorocarbons (CFC's) are responsible for the

depletion of the Ozone layer

- CFC's were used as: - An agent in forming Styrofoam - Propellants in aerosol cans - Coolants in air conditioners and refrigerators - It was cheap, non-toxic, and stable

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- Unfortunately, ultraviolet light reacts with the CFC

molecules to produce chloride ions

- Chloride ions act as a catalyst for the breakdown of

ozone (03) gas to normal oxygen gas (02).

Ozone is needed in the stratosphere where it prevents

ultraviolet light from reaching biological organisms at

the surface, which can experience cell damage (UV

Index).

Water Pollution - Pollutants reach water (lakes, streams, rivers) through

ground water and through the air from burning fossil fuels.

- Liquids and solid waste is carried away from homes as

sewage.

- Many rural areas have large tanks near homes called septic

tanks.

- Sewage treatment plants treat domestic waste, industrial

waste and water from street drains.

- Partially purified water, called EFFLUENT, runs into

rivers, lakes, or oceans.

Sewage Treatment - Three Stages

1. Primary - physical processes (filtering or sieving followed by settling)

- Waste material settled out is SLUDGE.

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2. Secondary - removes much of the organic compounds by bacterial decomposition. The resulting sludge is removed, and the remaining liquid effluent is treated with chlorine or exposed to UV light.

3. Tertiary - Effluent is now percolated through marsh or lagoon to remove any nitrates and phosphates that remain (plants growing here will use these compounds).

Ground Water - Water, which filters down through soil and fills the spaces

between particles of rock and soil and the cracks and fractures in

underlying rock - moves towards rivers, lakes, or the sea.

- Water can move between 15 meters per year, to a few

centimeters per century.

Aquifers - An area where permeable material can produce useful amounts of

water when a well is drilled into them - water naturally filters

through soil. Contamination can easily result from toxic herbicides,

pesticides, and solvents in industry and agriculture.

Hazardous Wastes - Any discarded material that contains substances that are known to

be poisonous, toxic, corrosive, flammable, or explosive.

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Assignment: page 245 "A Survey of

Household Hazardous Wastes"

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Lesson 8: Waste Management – The 4 R's

1. Reduce - use products that have less packaging.

Ex. bulk foods

2. Reuse - use over again or for new purposes.

Ex. pop bottles

3. Recycle - collect, break it down and rebuild into

other products

Ex. aluminum cans

4. Recover - reclaim either waste material or

energy.

Ex. Burn waste materials and use the energy

recovered and convert

it to electrical energy.

Cons Recycling does incur costs for transporting,

handling, sorting, cleaning, and storing.

Pros

Recycling paper requires 58% less water and produces 74% less air pollution

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***Conserves energy and resources***

Assignment 8: p. 252 #1-5 (copy question)

p. 253 – key terms

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Lesson 9: Landfill Construction and Design Solid Waste Disposal

Incineration - reduces volume to approximately 5% and the ash is disposed of in landfill.

However, gases produced contribute to air pollution. Sanitary Landfill Sites - To avoid possibility of any toxic wastes entering the water

supply by seeping into the ground water they use clay and/or plastic liner on the bottom.

Landfill must be monitored to make sure these is no leaching

Household things that leach:

Cadmium from old fridges

Lead from paints

Mercury from electrical equipment

- Anaerobic conditions created by burying organic waste results in the production of

carbon dioxide and methane. – methane gas will filter up to the surface, which creates the

possibility of explosion. Many landfills pipe the methane to the surface and burn or ‘flare

off' the gas in a controlled manner

Secure Landfills - are used to dispose of hazardous and toxic wastes.

Contents are enclosed by thick plastic liner and two or more layers of clay. A gravel bed

between the clay layers collects any leachate.

Leachate - the liquid that results when wastes decompose and rainwater filters down

through the landfill, is collected and sent to waste water-treatment centres.

Bioremediation - method of using living organisms to reduce hazardous substances

to less noxious forms.

Bioreactors - tanks containing bacteria species that can attack and break down

some of the more persistent and toxic wastes.

Assignment 9: p. 253 #1- 6, 10, 11 p. 259 #1-8 (copy question)

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Lesson 10: Review

Unit 3 Review

Pages 258 - 259 # 1-8, 10-12, 14-22 (in class and homework)

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Lesson 14:

Review Pages26O- 261 #23,25,27-38

Quiz Topics 4-6

Unit 3 Test