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Copy of Science 9 - Unit 3

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Chris Moore

on 14 May 2013

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Transcript of Copy of Science 9 - Unit 3

Science 9 - Unit 3
Environmental Chemistry Topic 1-
A Hair-raising Dilemma Your body needs Nutrients Organic Inorganic Carbohydrates
Lipids (Fats)
Vitamins Minerals
Macrominerals (100 mg/day or more)
Trace Elements (less than 100 mg/day) TAKE TWO PEBBLES... When you think about it,
all medicines are made from Elements!
Medicine is Chemistry! Everything that you put into your body
can be classified in greater detail. Some of those
Vitamins & Minerals.... B-9 (Folic Acids) Calcium Vitamin K Vitamin E Potassium Vitamin A Magnesium A Balanced Approach The Root Source... In order to help plants grow,
you need to know that everything
depends on a balance of elements. Problem: yellow striping on lower leaves & soil test indicates high levels of potassium and low levels of magnesium

Analysis: potassium is interfering with the plant’s ability to absorb magnesium

Solution: stop applying fertilizer containing potassium and apply more fertilizer with magnesium By knowing how plants use each element, agriculturalists can diagnose deficiencies and excesses, and act accordingly, to alleviate the problem. Commercial Fertilizers The three numbers on a bag of fertilizer refer to the percentage of nitrogen, phosphorus and potassium that is available to plants from that bag of fertilizer. Until the early 1900s, plants received their nitrates exclusively from nature. The artificial production of fertilizers increased the nitrogen levels available to plants in the soil. This has increased the amount of nitrogen in the environment by as much as 140 million tons per year.
Nitrogen is used by plants for increased plant growth. Crop production has doubled worldwide due to the use of artificial fertilizers and high-yield varieties.
Food production has increased worldwide as a result in most countries. Great isn’t it! – But wait: Consider the following –
It takes a lot of water and fertilizer to produce a crop of high-yield varieties
( VERY EXPENSIVE ) for farmers.
Monoculture – The planting of only one crop increases the chance of disease spreading through the entire crop. (a variety of crops allows for some of the crops to be resistant to the disease)
Chemical agents(pesticides) used to protect the crop reduce the amount of damage, but they are costly and have harmful effects on the environment. Issues Emerging From
High Productivity Topic 2-
A Growing Concern Topic 3-
How Do You Spell Relief Topic 4-
How Much Is Too Much? Topic 5-
Getting Away From It All Topic 6- N.I.M.B.Y.
There Is No Away In Throwing Pesticide use is
now common
practice worldwide. Herbicides control weeds.
Insecticides control insects.
Fungicides control
fungus and diseases. The use of chemicals,
such as DDT, was
originally thought to be
directed only at the
insects it was intended for. Unintentional harmful
effects to other species
resulted in a closer look. The invention of DDT
by Swiss chemist Paul Müller
was seen originally as a
breakthrough in medicine. During the 1950s it
was used to try to control
an outbreak of malaria.
...from mosquitoes. When DDT gets into the
food chain, biomagnification
can have devastating effects. Biomagnification
As you move up
the food chain,
the concentrations
of DDT are higher. Issues Associated With the Use of DDT The DDT Story What’s Bugging You? The use of DDT was
recognized as having
potentially harmful effects. Banning its use would also
negate the positive effects it
was having in controlling malaria Nothing else proved to
be as effective in controlling
the insects that carried malaria. Where To Now? No matter how it is developed,
a pesticide is used
to control pests. Research and development
into newer and safer pesticides
has resulted in these pesticides
breaking down faster in the
environment after they have
been applied. but it still remains a hotly debated issue. Should DDT be banned completely? In the future researchers
must determine what effects
combinations of these pesticides
will have on the environment
and ultimately us. Acids and Bases Properties and Examples Acids taste sour,
are soluble in water
and undergo similar
chemical reactions,
have a pH of less than 7 Bases taste bitter,
are soluble in water,
feel slippery,
and react with acids,
have a pH of more than 7 Substances that are
neither acidic nor basic,
such as water,
are said to be neutral. pH is a measure of the concentration of hydrogen ions in a solution. pH: Powerful Scale Neutralization Acids and bases react together when they are mixed. This type of reaction is called neutralization. Acid in your stomach has a normal pH of 2. This acid helps in the digestion of food and kills off bacteria. If you eat too quickly, or are under stress, your stomach produces an excess amount of gastric acid (giving you heartburn). To neutralize the excess acid, an antacid tablet is swallowed. This antacid is a mild base. (eg. Tums, Rolaids, Milk of Magnesia, Pepto Bismal) Sulfur, nitrogen and carbon oxides emitted from industries combine with water vapor in the air to produce sulfuric, nitric and carbonic acid. SO2(g) + H2O(l) H2SO3(aq) [ sulfurous acid ] SO3(g) + H2O(l) H2SO4(aq) [ sulfuric acid ]
2NO2(g) + H2O(l) HNO2(aq) + HNO3(aq) [ nitrous and nitric acid ]
CO2(g) + H2O(l) H2CO3(aq) [ carbonic acid ] These pollutants then fall to the ground as acid precipitation with a pH lower than normal rain (which is about 5.6) Acid Precipitation
... chemical change reduces soil fertility
... slows tree growth
... kills organisms in lakes & streams
... corrodes exposed metal surfaces
... leaches toxic chemicals from the soil
... breaks down stone and limestone
…damages or destroys aquatic ecosystems International Agreements In 1996 an agreement between Canada and the US targeted a 10% reduction in industrial exhaust emissions by the year 2000. Vehicle emissions for cars built before 1998 was also targeted to be reduced by 60%. Using Chemistry to Control Acid Effects To neutralize acid rain precipitation, lime is added to lakes. Not Lime as in Lemons and Limes, but Lime as in the Calcium form. (calcium hydroxide - which is a base) This is not necessary in Western Canada because as glaciers melted they left behind rich deposits of alkaline materials. This material lying at the bottom of lakes neutralizes the acids that enter the lakes. Using Chemistry to Control Harmful Emissions The concentration of chemicals in the environment can be changed using different techniques. Reducing emissions at the source is more economical and has a greater effect than dealing with emissions once they are in the environment. Catalytic converters contain a ceramic or wire honeycomb-like structure that is coated with a thin layer of metallic catalysts, which speed up chemical reactions, without being used up. Catalytic converters encourage complete oxidation so fewer harmful oxides are produced. Catalytic converters in vehicles. It helps the formation of CO2 and H2O, reducing CO and NO2(harmful oxides!) Acid Precipitation –
A Global Concern here's the result of a bad converter Scrub Those Cares Away The oxide emissions from industries and thermo-electric power plants that burn coal can be a major source of oxides, depending on the concentration of sulfur in the coal. The addition of scrubbers is a technological solution to reduce oxide emissions. A scrubber is a device that uses a sorbent that absorbs or captures the sulfur oxides. Newer scrubber technologies have the potential to be more effective, environmentally friendly, and economical. The COBRA system uses a sorbent of small aluminum oxide (impregnated with copper) beads. Pollution is any alteration of the environment producing a condition that is harmful to living organisms. How Much Is That? Water is a vital source of life for all living organisms. How would you know if water is polluted? A pollutant is any material, or form of energy that can cause harm to living organisms. To measure how much of a pollutant is present in the environment, we measure its concentration. Concentrations of chemicals can be measured in …
parts per million (ppm)
parts per billion (ppb)
parts per trillion (ppt)
or sometimes
milligrams per Litre (mg/L), which is the same as ppm To visualize ppt - one part per trillion would be equal to:
1 quarter in a stack 2000 km high,
1 second in 32,000 years,
or 1 cent in $10 billion. The Danger Is In the Dose Toxicity is the ability of a chemical to cause harm to an organism. Acute toxicity occurs when serious symptoms occur after one exposure to the toxic substance. Chronic toxicity occurs when the toxic substance accumulates as a result of many exposures over time. Lethal Dose 50 Scientists measure toxins in LD50 amounts. LD stands for ‘Lethal Dose”
50 represents 50% of the subject group that will die,
if they are given the specified dose, all at once. This is the Chronic (long term)
effect of Mercury poisoning! An Acceptable Risk? Testing programs follow strict guidelines to prevent fatal doses being consumed Most of our fatal-dose information for humans comes from accidental-exposure case studies Why would anyone want to volunteer to be a test subject in a lethal dose test? Thalidomide Issue Thalidomide was originally developed as a sleeping pill. Its use in the 1950s and 1960s by pregnant women, resulted in thousands of birth defects. The Evaluation of Risk What risks do we take, and of those, which are acceptable, or not?
Contemplate, for a minute, the following – to put it in perspective: To receive an LD50 dose of a particular substance that was tested for mice – a human would have to drink 70 cups of that substance – all at one – in one sitting

• LD50 can vary from animal to animal even differing between rats and mice.

• In addition, LD50 value depends on the type of exposure: ingestion (eating or drinking), inhalation (breathing) or skin contact. As the world population grows waste production also grows and the proper handling of this waste is a concern. Environmental Monitoring Biological Indicators of Water Quality Point Versus Non-point Sources Non-persistent wastes will naturally break down in a short amount of time. Ex. Fertilizers, sewage Persistent pollutants accumulate and take a long time to degrade (break down). Ex. Pesticides, Petroleum products It is the concentration of these wastes that can affect living organisms. Monitoring keeps track of something for a specific purpose. Water Quality is determined using chemical and biological indicators according to what the water is going to be used for. Pollution Water Quality Aquatic Organisms Affects Affects Microscopic organisms
can cause serious health problems if they are present in large numbers. BACTERIA Samples are taken to identify their presence to avoid contamination of the water supply. macroinvertebrates Large-without vertibrate (backbone) ... worms, leeches and midge larva thrive in polluted water, as they require only small amounts of dissolved oxygen for survival … there will likely be no fish, shrimp, mayfly or stonefly invertebrates in water that has Oxygen levels less than 8 ppm
Pollutants entering the environment from specific locations are point source pollutants. Ex. Smokestacks, drainpipes Non-point source pollutants are those that enter the environment
from locations that cannot be easily monitored or controlled. Ex. Fertilized field, feedlots. The 4Rs – Reduce, Reuse, Recycle and Recover
- have provided a basic framework to reduce the amount of waste pollutants that are produced.
The acronym N.I.M.B.Y stands for NOT IN MY BACKYARD
Blowing In The Wind There are three stages of transport of substances in the environment:
• Release of chemicals at the source
• Dispersion of the chemical into the atmosphere
• Collecting of the chemical in soil or water
The direction and distance that airborne chemicals travel have factors;
• The properties of the chemical pollutant
• The wind speed
• The direction of the prevailing wind
most airborne particles now are from human activities
dust/erosion (agriculture)
in the past, most airborne particles came from natural sources
forest fires
Stratospheric Ozone and CFC
Controlling Water Pollution in Surface Waters & in
Ground Water
The thinning of the atmosphere is caused by our use of chlorofluorocarbons ( CFC’s ). In the past these chemicals were used in:
aerosol spray cans
refrigerators Most surface water pollution is due to everyday activities, such as washing clothes or watering lawns.
Hazardous chemicals can enter surface water and groundwater, from the air, as well as from runoff from
agricultural fields, industrial sites, storm sewers, sewage treatment plants
Septic tank–
A septic tank is a large underground container that
traps grease and large solids
Water that soaks into the soil is collected in a zone called the groundwater zone
Biodegradability and the Environment
Biodegradation occurs in the environment because living things
(earthworms, bacteria and fungi)
are actively breaking down organic substances, including many pollutants. What are hazardous wastes?
Can you list any hazardous
wastes found in your house? Write down three common
household wastes listed in
this video.... ready?
A hazardous waste is any discarded material that contains substances that can be
flammable, or
explosive please read page 242.
check out the table at the bottom of the page after you've read the page. Please read pages
247 and 248
Landfill Construction and Design Please read p 252 Hooray, the Unit is done... time to celebrate! jeopardylabs.com/play/science-9-unit-3-review jeopardylabs.com/edit/science-9-unit-3-review The Roles of Nutrients in Fertilizer

Nitrogen - Promotes growth and green, healty plants
Phosphorus - Promotes germination and early root development
Potassium - Encourages fruit and flower development Oxides!! 3 Types of Pesticides! The lime neutralizes the acidic water. This is only a temporary solution as rain and rivers continually bring more
acidified waters to the lake. Because airborne emissions can
travel vast distances, countries
must work together to reduce them. Why is acid precipitation a bigger
problem in Eastern Canada than in
Western Canada? (Fig. 3.10 on Pg. 204)
- More population
- More industry
- Winds from U.S.A. Emissions from Vehicles Emissions from Industry Traditional scrubbers remove SO2 by reacting it with CaO(lime) to form CaSO3. This slurry is then disposed of in landfills. A power plant might produce millions of tonnes of waste CaSO3 every year!! These beads capture the SO2, and are then treated to release the SO2. This trapped SO2 can be treated and used to produce sulfur, sulfuric acid, and even fertilizer. The beads are then reused and no waste goes to the landfill! Scrubber Comparison Traditional COBRA
- produce lots of waste - no waste products
for landfills
- must continually add CaO - beads are reusable
- cheaper to start up - more expensive but
will pay itself off
- pay to dispose of waste - get product to sell First, we need to know the difference
between pollution and a pollutant. Acceptable Risk 0 Phosphorus promotes plant growth
-occurs naturally in most soil and water under 0.5 ppm
-in excess algae grows then dies and causes low oxygen levels and high carbon dioxide levels that kills other organisms
Nitrogen - clean water usually has 0.1 to 0.3 ppm
- excessive amounts is a sign of the decomposition of organic matter Thermal Pollution
Warm water can not hold as much dissolved oxygen as cold water
Thermal Pollution harms organisms by:
1. Decreasing the amount of available oxygen
2. Increasing the demand for oxygen by increasing the metabolism of aquatic organisms. 2 Types of Landfills Sanitary Landfill (Pg. 249 Fig. 3.34)

- garbage is covered each day with soil to prevent litter avoid attracting scavengers.
- a clay layer and plastic is used to prevent fluids from contaminating ground water
- the leachate is collected and sent to a waste water treatment plant
- methane gas and CO2 is given off when organic waste is buried
methane gas is burned off or used for electricity (recover) Secure Landfill (Pg. 250 Fig. 3.35)

- Used for toxic and hazardous wastes
- Similar to a sanitary landfill, but with
additional layers to prevent the mixing
and leaking of chemicals
- Wells are drilled outside the site to
monitor for any leaks Bioremediation – using living organisms to fix a pollution problem
-plants take in the pollutant through their roots
-plants store them or can change them into something less toxic
-Ex. Mustard, fescue, poplar tree, bacteria Sewage Treatment (Pg. 240, Fig. 3.29)

Primary Treatment
- removes large solids

Secondary Treatment
- bacteria decomposition breaks down organic
compounds, sludge is removed, and effluent(remaining liquid) is treated by chlorination or UV light

Tertiary Treatment
Passing the effluent through a lagoon or marsh removes
nitrates and phosphates, even some heavy metals Ground Water Pollution (Pg. 241)
- Aquifers are large areas of useful
ground water. Contaminants can
become concentrated in aquifers.
- Ground water is difficult, if not
impossible, to clean up
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