Environmental Chemistry - Ms. Nielsen's Courses...

31
onmental Chemistry

Transcript of Environmental Chemistry - Ms. Nielsen's Courses...

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Enviro

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enta

l Chem

istry

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ENVIRONMENTAL CHEMISTRY

Table of Correlations

Practice Unit TestSpecific Expectation Questions Questions 2006 PAT

Students will.,

C. 1. Investigate and describe, in general terms, the role of djerent substances in the environment in supporting or harminghumans and other living things.

Cd.1 identify common organic and inorganic substances that 1, 3, 4 1

are essential to the health and growth of humans andother living things, and illustrate the roles served bythese substances

C.1.2 describe in general terns, the forms of organic matter 5, 6, 7

synthesized by plants and animals, includingcarbohydrates, proteins and lipids

C 1.3 describe and illustrate processes by which chemicals 8, 9, 10 2, 4 22

are introduced to the environment or theirconcentrations are changed

C. 1.4 describe the uptake of materials by living things through 11, 12, 13, 14, WR 1, 14

ingestion or absorption, and investigate and describe 34evidence that some materials are djcull for organismsto break down or eliminate

C. 1.5 identify questions that may need to be addressed in 14, 15

deciding what substances-in what amounts-can besafely released into the environment

6.2. Identify processes for measuring the quantity of different substances in the environment and far monitoring air andwater quality.

C.2.1 identify substrates and nutrient sources for living things 17 11 27

within a variety of environments

C 2.2 describe and illustrate the use of biological monitoring 18 12

as one method for determining environmental quality

C2.3 identify chemical factors in an environment that might 16, 19, 21 6, NR1 25affect the health and distribution of living things inthat environment

C Z4 apply and interpret measures of chemical 20,21, 22 8 28, 29

concentrations in parts per million, billion or trillion

C.2.5 identify acids, bases, and neutral substances, based on NR1, 23, 24 10, 13 23

measures of their pH

C.2.6 investigate, safely, and describe the effects of acids and 25, 26 26

bases on each other and on other substances

C.2.7 describe effects of acids and bases on living things 27

Class Focus Castle Rock Research68

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C.3. Analv_e and evaluate mechanisms affecting the distribution of potentially harnrftdsubstances within an enrirnrunrru.

C.3.1 describe mechanisms for the transfer of materials 28.29.30 7.9through air, water and soil; and ident /' factors thatnrav accelerate or retard distribution

C.3.2 describe mechanisms for biodegradation, and interpret 2, 31, 32 24itformation on the biodegradability of dferentmaterials

C.3.3 comprehend information on the biological impacts of 33, 36 3, 14hazardous chemicals on local and globalenvironments, by:•

interpreting evidence for environmental changes inthe vicinity of a substance release

interpreting LD50 data and other informationson toxicity

ident(,ing concerns with the disposal ofdomestic wastes, such as paints and oils, andindustrial wastes

C.3.4 describe and evaluate methods used to transport, store. 37 5and dispose of hazardous household chemicals

C.3.5 investigate and evaluate potential risks resulting from 35 NR2 30consumer practices and industrial processes, andident j, processes used in providing information andsetting .standards to manage these risks

C.3.6 identifi' and evaluate information and evidence related NR2 WR2to an issue in which environmental chemistry plays rrmajor role

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Environmental Chemistry

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ENVIRONMENTAL CHEMISTRY

C.1.1 identify common organic and inorganicsubstances that are essential to the healthand growth of humans and other livingthings, and illustrate the roles served bythese substances

COMMON ORGANIC AND INORGANIC

SUBSTANCES

All matter is classified as either inorganic ororganic in composition. Inorganic matter includessubstances that have elements such as magnesium,phosphorus, potassium, and calcium in their

molecular structure. These elements are essentialfor the proper growth of plants and animals for thefollowing reasons:

• Magnesium is essential for carrying outphotosynthesis and maintaining metabolicreactions in animals.

• Potassium stimulates protein production inplants and muscle contractions in animals.

• Calcium and phosphorus are essential forcarrying out cell division in plants and forgrowing teeth and bone in animals.

• Nitrogen is required for building proteins.Nitrogen fixing bacteria are found in the roots ofsome plants that help convert nitrogen into auseable form for the plants.

Organic matter includes the majority ofcompounds that have the element carbon in theirmolecular structure. Some of these compoundsare essential for proper growth and development.Common organic compounds used by plants andanimals are carbohydrates, lipids, and proteins.

Living organisms require inorganic and organicnutrients in varying amounts. Compoundsrequired in large amounts such as, carbohydrates,lipids and oxygen are called macronutrients.Compounds required in much smaller amountssuch as vitamin A and iodine are calledmicronutrients.

Plants and animals require nutrients in specificamounts; too much or too little can be harmful.For example, if soil contains a high level ofpotassium and a low level of magnesium, theleaves on a plant growing in the soil will developyellow stripes.

Practice Questions: 1, 3, 4

C.1.2 describe in general terms, the forms oforganic matter synthesized by plants andanimals, including carbohydrates,proteins and lipids

ORGANIC SUBSTANCES SYNTHESIZED

BY PLANTS AND ANIMALS

The organic substances synthesized by plants andanimals are carbohydrates, lipids, proteins, andnucleic acids.

Carbohydrates are organic substances made up ofcarbon, hydrogen, and oxygen atoms. They can besimple molecules, such as glucose, fructose, andsucrose; or complex molecules, such as starch,cellulose, and glycogen. Green plants synthesizeglucose during photosynthesis.

Lipids are also composed of carbon, hydrogen,and oxygen atoms. They are fats, oils, and waxesproduced by plants and animals. Humans storeenergy from food in the form of fat, and humanskin produces oils for protection. Plants produceoils and fats in their nuts and seeds, such aspeanuts, walnuts, and canola seeds. Fat moleculesare made up of fatty acids and glycerol.

Proteins are molecules composed of carbon,hydrogen, oxygen, and nitrogen atoms.Proteins are essential for the growth and repair oftissue, and they can be a source of energy.Proteins are made up of amino acid moleculesjoined together and arranged in a specificsequence.

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Nucleic acids are the largest complex moleculesfound in living organisms. A cell containsdeoxyribonucleic acid (DNA) and ribonucleic acid(RNA). A complex molecule of DNA or RNA iscomposed of phosphate, a simple sugar (ribose ordeoxyribose), and nitrogen -containing bases.Nucleic acids are responsible for the transmissionof characteristics and for controlling cell activity.

DNA structure

Practice Questions: 5, 6, 7

C1.3 describe cnrd illustrate processes bywhich chemicals are introduced to theenvirotttnent or their concentrationsare changed

CHEMICALS INTRODUCED INTO THE

ENVIRONMENT

Both natural processes and human activitiesrelease chemicals into the environment.Carbon dioxide is released naturally into the airduring cellular respiration by animals.Cellular respiration, the process by which yourbody uses the oxygen and chemicals in food toproduce energy. releases carbon dioxide as aby-product. Carbon dioxide and other compoundsare also released in the air as a result of humanactivities, such as driving a car or burning coal toproduce electricity. The accumulation ofunwanted waste matter in the environment iscalled pollution. Pollution causes changes in theenvironment that are harmful to living things.

The following activities pollute the environment:

• Solid waste disposal

• Waste water disposal

• Combustion

• Agricultural activities

• Industrial processes

Many of the chemicals introduced into theenvironment by these processes can be brokendown naturally, but some of them cannot.The chemicals that cannot break down accumttlatcin the environment and have long-term effects onthe ecosystem.

AGRICULTURAL ACTIVITIES USE

CHEMICALS

Agricultural activities are responsible forintroducing many chemicals into the environment.In order to enrich the soil and improve cropyields, farmers use fertilizer. Fertilizers containnitrogen, phosphorus, potassium, and sulfur.These elements are important for plant growth.However, their overuse pollutes soil and water.Fertilizers that leach from the soil into watersystems promote excessive plant growth.The decay of these plants results in oxygendepletion.

Farmers also use pesticides to improve their cropyields. Pesticides are chemicals designed to killorganisms that damage crops. Herbicides areused to kill or control weeds, insecticides killor control insects, and fungicides kill fungi.All of these chemicals pose a serious threat tothe ecosystem.

SOLID WASTE DISPOSAL

Solid waste is garbage collected from households,industries, and construction sites. While some ofthis waste can be reused or recycled, a largeamount is deposited in landfills. Plastic liners andclay are used in sanitary landfills to preventchemicals from leaching into the ground.

Some waste is too hazardous to be dumped in alandfill, and this waste is often burned inincinerators. Incinerating garbage producesair pollution.

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WASTEWATER DISPOSAL

The wastewater collected from bathrooms,kitchens, and laundry rooms is called sewage.Sewage is made up of both dissolved andundissolved substances. In rural areas, septictanks are used to collect sewage. Bacteria in theseptic tank break down the harmful substancesbefore the substances are released into the soil.In urban areas, sewage is pumped to sewagetreatment plants. Once the sewage has beenbroken down by bacteria or other chemicalprocesses, the treated wastewater (called effluent)is released into nearby rivers and lakes.

COMBUSTION

Fossil fuels such as coal, petroleum, and naturalgas are often burned in order to release energy.During a combustion reaction with these fuels,large amounts of carbon dioxide and varyingamounts of sulfur dioxide are produced.Many combustion particulates are heavier than air,ending up in the soil and water. Sulfur dioxidethat is released combines with water in the

atmosphere and causes acid rain or snow.

Combustion in vehicles is a major source ofground level ozone. High concentrations ofground level ozone cause breathing problems forpeople with respiratory diseases.

INDUSTRIAL PROCESSES

Harmful wastes are released into the environmentduring various industrial processes, such as theprocessing of crude oil. Crude oil is a mixture ofmany compounds including those with hightoxicity. It is important to minimize the release ofthese compounds into the air when producingpetroleum.

Practice Questions: 8, 9, 10

C.1.4 describe the uptake of materials by livingthings through ingestion or absorption,and investigate and describe evidence thatsome materials are difficult for organismsto break down or eliminate

ABSORPTION OF NUTRIENTS IN PLANTS

Both organic and inorganic chemical compoundsare absorbed by plants. Plants absorb thesesubstances from the air and from the soil. Water isrequired to transport nutrients to the cells and tocarry waste products out of the cells. In plants,osmosis is one of the processes by which water inthe soil moves into the root cells of a plant.The water passes through a semi-permeablemembrane, the cell wall, from an area that has ahigh concentration of water to an area of lowconcentration of water. In the diagram the waterin side A will move into side B through osmosiseven though there is more sugar, and therefore lesswater, in side A. This is the opposite of diffusionwhere compounds move from areas of higherconcentration to areas of lower concentration.

Semi-permeablemembrane

0 0 o'I

0 0

A

B

o - Sugar moleculen -Water molecule

Plants need to absorb nutrients through their roots.The concentrations of these nutrients can be higherin the roots than in the surrounding soil.This means that the nutrients needed in highconcentrations will not diffuse into plant rootsfrom the soil. The roots absorb high amounts ofthese nutrients through a process called activetransport. Active transport is the movement ofmaterial from an area of low concentration to anarea of high concentration. Unlike osmosis anddiffusion, this process requires energy.

0 0

'• .0 o 10

0 0 0 0 .1I.

• 0 0.0,

00.

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INGESTION AND ABSORPTION OF NUTRIENTSIN ANIMALS

Humans and other animals get nutrients from thefood they eat. The process of taking in food iscalled ingestion. The food is broken downmechanically and chemically into simplersubstances that can be used by the body.Hydrolysis is a process in which large organicmolecules, such as sugars, are broken downwith water. Complex maltose sugars arehydrolyzed into simple glucose sugars. Once themaltose sugar has been broken down, the glucosenutrients are small enough to be absorbed into theblood stream. The blood transports the nutrientsto appropriate blood cells for use or storage.

Because toxic substances that bioaccumulate

become part of the tissues of an organism's body,they will be passed on when that organism iseaten. As these compounds are passed up througheach trophic level, they accumulate in greaterconcentrations in organisms of higher trophiclevels. This process is called biomagnitication.

BIOACCUMULATION ANDBIOMAGNIFICATION

Up a O.m ppb

When harmful chemicals are introduced into anenvironment, they can be absorbed by livingorganisms. Some toxic chemical compounds thatare absorbed into an organism's body do not easilybreak down and do not get removed from theorganism's body. Even if there are very low levelsof the toxic compound in an organism'senvironment, the compound can accumulate in theorganism's body over time, making the organismsick or even killing it. The process of low levelsof chemicals building up in the bodies of livingorganisms is called bioaccumulation.

Each level of the food chain is called atrophic level. Producers make up the first trophiclevel, primary consumers (herbivores) make up thesecond trophic level, and secondary consumers(carnivores) make up the tertiary (third) and highertrophic levels. Bioaccumulation can affectorganisms at each trophic level.

The given diagram shows a food pyramid withtrophic levels and relative concentrations ofharmful substances (in ppm) at each level.

The effect of a "red tide" is an example of howbioaccumulation affects consumers at differenttrophic levels. A harmful algal bloom or "redtide" occurs in the ocean when there is the rapidreproduction of single-celled algae, orphytoplankton, which produces a natural toxin.When toxin-producing phytoplankton begin toreproduce rapidly, the organisms that feed on themaccumulate the toxin in their bodies. Shellfish arefilter-feeders that store the toxins from "red tides"in their bodies for several weeks. Shellfish are atthe second trophic level and are not usuallyseverely harmed by the toxin but these harmfulalgal blooms can make organisms at higher trophiclevels that eat the shellfish such as fish, whales,sea lions, and people very ill.

Practice Questions: 11, 12,13, 14, 34

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C.1.5 identify questions that may need to beaddressed in deciding what substances-in what amounts-can be safely releasedinto the environment

SAFE RELEASE OF SUBSTANCES INTO

THE ENVIRONMENT

Motor vehicles are a primary source of airpollution. Combustion in the engine of a motorvehicle releases nitrogen oxide, carbon monoxide,and carbon dioxide pollutants into the air.What level of pollution emissions by vehicles isconsidered to be acceptable? How can vehicleemissions be reduced to safe levels? These aresome of the questions that need to be addressed.

In an attempt to reduce the pollution emissionsfrom motor vehicles, car manufacturers have

designed more energy efficient engines that bumless fuel. Car makers have also designed acatalytic converter for the muffler system thatremoves pollutants from the vehicle exhaust.Human actions like driving small vehicles,carpooling, and taking public transit help to reduceemissions in the atmosphere.

Landfills are specially designed areas where solidwastes are disposed of. Selecting a landfill site isnot an easy task. The location must be one that iseconomical to get to, environmentally safe,and large enough to store the increasing amount ofhousehold waste. Landfills are constructed with athick clay liner which prevents the garbageleachate from seeping into the nearby watersystem. Methane gas produced by the rottinggarbage in a landfill must be safely contained.Sometimes the gas is collected and piped to apower plant where it is used as fuel to produceelectricity.

Finding a suitable landfill site is becoming moredifficult. That is why it is important to reduce thewaste matter that ends up in a landfill. Personalactions such as reusing and recycling can reducethe amount of solid waste taken to landfills.

It is important to consider the effects thatnatural and human activities have on theenvironment and to take steps to reduce the impactof these processes.

Practice Questions: 14, 15

C.2.1 identify substrates and nutrient sourcesfor living things within a variety ofenvironments

SUBSTRATE AND NUTRIENT SOURCES

A substrate is any surface on which a plant oranimal lives or moves. It may be abiotic or biotic.In biological terms, nutrient stores contained in thesubstrate are essential to the survival of organisms.

Coral reefs are made up of millions of animalscalled polyps that secrete calcium carbonate shells.These hard shells are the substrate, or living area,for molluscs, worms, crustaceans, echinoderms(such as sea cucumbers and sea urchins), andsponges. Food particles that settle on the surfaceof the coral provide nutrients to feed the organismsthat are living there. Algae use the reef as asubstrate, while organisms such as the sea urchinuse the algae as food.

The forest floor is one of the richest sources ofnutrients in a forest ecosystem. It is mainly madeup of decaying vegetation such as branches andleaves. As they decay, minerals and organiccompounds are released and added to the nutrient-rich soil. The soil provides the substrate for alarge number of decomposers such as bacteria,fungi, algae, and worms, as well as for the treesand other vegetation.

Practice Question: 17

Class Focus 74 Castle Rock Research

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C.2.2 describe and illustrate the use ofbiological monitoring as one method fordetermining environmental quality

BIOLOGICAL MONITORING

The invertebrate aquatic organisms found ina water habitat are an excellent indicator ofwater quality.

If a water supply has lots of midge larvae, someleeches, and no caddisfly larvae, it has littledissolved oxygen and is poor quality. If the waterhas caddisfly and mayfly larvae, it is rich indissolved oxygen and is good quality.

THE IMPORTANCE OF MONITORING

AIR QUALITY

Air is a blend of several gases. It is just asimportant as water for sustaining life.

21% oxygen gas

Stonefly larva

Factors such as temperature, pH, and dissolvedoxygen affect the kind of organisms found inwater habitats. Organisms living in a stagnantpond are different from the organisms living in astream or large lake.

Biological Indicators of Dissolved Oxygen inWater

Poor Quality Moderate Good Quality(0 to 4 parts Quality (5 to (9 to 10 partsper million of 8 parts per per million ofoxygen) million of oxygen)

oxygen)

Midge larvae Freshwater CaddisflyLeech clam larvaeMosquito Dragonfly StoneflyWriggler nymph larvae Mayfly

Fairy shrimp larvae

The quality of air should be carefully monitoredand good air quality maintained. Collecting dataabout chemicals in the air provides informationabout immediate and long-term trends.Presently there is concern about emissions ofsulfur dioxide, nitrogen oxide, carbon dioxide,and chlorofluorocarbons in the atmosphere andthe effect of these emissions on the environment.

Practice Question: 18

THE KEY - Science 9

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C.2.3 identify chemical factors in anenvironment that might affect the healthand distribution of living things in thatenvironment

CHENIICAL FACTORS AFFECTING THE

DISTRIBUTION OF LIVING THINGS

Chemical concentrations indicate the quality ofwater and may affect the distribution of livingorganisms within an ecosystem.

Water has oxygen dissolved within it, which isessential for the survival of aquatic life.The amount of oxygen dissolved in water dependson factors such as the temperature, the rate ofphotosynthesis, and the number of organismspresent in that water. The number and diversity ofliving things is greater in water that has a goodsupply of dissolved oxygen.

Phosphates and nitrates enter the water supplythrough sewage and runoff containing fertilizers.Phosphorus and nitrogen are elements essential forliving organisms, but high concentrations of theseelements can cause adverse effects in anecosystem. These chemicals cause an overgrowthof algae in the aquatic system.

Bacteria break down dead plant matter and useoxygen in the process. This depletes the supply ofoxygen for plants and animals living in the water.

Natural rainwater has an average pH of 5 and atypical range from pH 4.5 to 5.6. However, anyprecipitation with a pH lower than 5.6 is calledacid rain. When acid rain reaches the ground,it mixes with other water sources, increasing theacidity of these water sources. Fewer organismsare able to survive in an acidic environment.

Pesticides are chemicals that farmers use tocontrol unwanted insects and rodents. Pesticidesusually have long term effects because theyremain in the environment long after theirintended use. It is possible that insects candevelop a tolerance to a certain pesticide, creatingthe need for a stronger pesticide. Chemicalpesticides can make the water and soil toxic.As well, some pesticides are not broken downwithin organisms and can bioaccumulate.

Elements such as mercury, copper, lead, zinc,cadmium, and nickel are heavy metals.These elements are used in many commercialproducts such as batteries, thermometers, andelectronic equipment. Heavy metals can enterthe water system and accumulate in the bodiesof animals. This causes illness, deformities,and death.

Practice Questions: 16,19, 21

C.2.4 apply and interpret measures of chemicalconcentrations in parts per million, billionor trillion

MEASURING IN PARTS PER MILLION

Concentrations of chemicals in the environmentare commonly measured in parts per million (ppm)or milligrams per litre (mgIL).

ppm _ grams of solute X 106

grams of solution

mg _ milligram of solute

litre

litre of solution

Example

One part per million means one unit of chemicalis found in one million units of solution. If 1 mLof food colouring is dissolved in 999 mL of water,what is the concentration of the food colouring inthe water in ppm?

Solution

Let x be ppm.999 mL water + 1 mL food colouring =1 000 mL

lmL _ x

1 000 mL 1 000 000x =1 000 ppm

The concentration of food colouring is 1 000 ppm.

Practice Questions: 20, 21, 22

Class Focus Castle Rock Researchil l 76

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C.2.5 identify acids, bases, and neutralsubstances based on measures of their pH

ACIDS, BASES, AND NEUTRAL

SUBSTANCES

An acid is a compound that, when dissolved inwater, has a pH less than 7. An acidic solutionthat has a pH of 1 would be a much stronger acidthan a solution with a pH of 4. Stomach acid(pH 1) is more acidic than tomato juice (pH 4).Lemon juice is another example of an acid.

A base is a compound that forms a solution with apH higher than 7. A solution with a pH of 14 is a

strong base. Bases taste bitter and feel slippery.Baking soda is an example of a base.Neutral substances are neither acidic nor basicand have a pH of 7. Distilled water and blood areneutral substances.

The acidity of a solution is described by pH.The pH is a measure of the concentration of thehydrogen ions present in that solution.Substances have pH levels between 0 and 14 onthe pH scale.

The difference between one whole number andthe next on the pH scale represents a ten-folddifference in the concentration of hydrogen.For example, a substance with a pH of 2 is10 times more acidic than a substance with apH of 3 and 100 times more acidic than asubstance with a pH of 4 (10 x 10 = 100).

To identify a substance as an acid, a base, orneutral, use a chemical indicator such as pH paper.For example, red litmus paper turns blue in a baseand remains unaffected in an acid. Blue litmuspaper turns red in an acid and remains unaffectedin a base. Other chemical indicators arephenolphthalein and bromothymol blue.

Practice Questions: NR1, 23, 24

C.2.6 investigate. safely, and describe the electsof acids and bases on each other and onother substances

NEUTRALIZATION

A neutralization reaction is a reaction between anacid and a base. When an acid reacts with a base,salt and water are produced.

Example

HCI(aq)

+ NaOHlaq)

NaCl(,) + HzO1)

Hydrochloric

Sodium

Sodium

Wateracid

hydroxide

chloride(an acid)

(a base)

(salt)

Practice Questions: 25, 26

C2.7 describe effects ofacids and bases onliving things

EFFECTS OF ACIDS AND BASES ON

ORGANISMS

Most industrial processes emitwaste gases such as carbondioxide, sulfur dioxide, andnitrogen oxide. These gasesdissolve in water dropletsin the air to form acids.Carbon dioxide forms carbonic acid, sulfurdioxide forms sulfuric acid, and nitrogen oxideforms nitric acid. Acid rain pollution occurs whenthe water droplets containing these dissolved gasesfall to the ground and run into lakes and ponds.Acid rain also causes chemical changes in the soil,reducing its fertility. Acid rain hinders the growthof some plants, corrodes metal surfaces, anddeteriorates limestone and marble.

The effects of acid rain can be reduced by treatinglakes with lime (calcium oxide). Lime isdissolved into the water and neutralizes the acidpresent in the lake water.

Practice Question: 27

THE KEY - Science 9

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C.3.1 describe mechanismsfor the transfer ofmaterials through air, water and soil;and identify factors that may accelerateor retard distribution

TRANSPORT OF MATERIAL THROUGH

AIR, SOIL, AND WATER

The transport of substances in the environmentoccurs in three stages: the release of chemicalsfrom the source, the dispersion of chemicals intothe atmosphere, and the deposition of chemicalsin soil or water.

Pollutants transported through air are calledairborne pollutants. The direction and distancetravelled by airborne chemicals is determined by

factors such as the properties of the chemicalpollutants, the speed of the wind, and the directionof the wind.

Hazardous chemicals can enter into surface wateras effluent from sewage treatment plants or runofffrom agricultural fields that use pesticides andfertilizers. If a low concentration of a chemicalcan be dissolved in water and dispersed over awide area, the toxicity of the chemical will bereduced. The problem lies with insolublesubstances deposited near the pollution source.As they accumulate, the substances will create anarea of contamination.

Water flows through the ground and seeps down inthe soil. It will eventually reach the groundwaterzone. Groundwater moves, but the rate at which itmoves is very slow.

This means that it takes a long time for pollutantsdissolved in groundwater to disperse. If thegroundwater is used as drinking water, the toxicpollutants can become a health hazard.

The movement of groundwater is affected bypores in the soil. Permeable soil has largerpores and more space between particles. It iseasier for pollutants to flow and spread throughpermeable soil.

Soil pollution by hydrocarbons takes place as aresult of the use of fossil fuels in vehicles andindustries. These hydrocarbons do not dissolve inwater; they cling to the soil particles, changing thesoil properties. Most hydrocarbons are toxic toboth plants and animals.

Practice Questions: 28, 29, 30

C. 3.2 describe mechanisms for biodegradation,and interpret information on thebiodegradability of different materials

BIODEGRADATION

The concentration of pollutants in the environmentcan be decreased naturally. Certain organisms,such as bacteria, fungi and earthworms, candecompose pollutants in the soil. These organismsbreak down complex organic molecules intosimpler substances in a process calledbiodegradation. Bacteria are especially importantin this process. Some bacteria require oxygen tocarry out biodegradation. When this process needsoxygen, the process is referred to as aerobicbiodegradation.

Other bacteria can only survive under conditionswith no oxygen. These bacteria decomposeorganic material in anaerobic biodegradation.

The process of biodegradation is affected by the

availability of nutrients, pH, temperature, soilmoisture, and oxygen supply. An environmentthat is too cold or too dry is unfavourable formicroorganisms to decompose matter.

Bioreactors have been built to increase the rate ofbiodegradation. Bioreactors are designed toprovide the optimal conditions for biodegradationat all times. A sewage treatment plant hasbioreactors to speed up the decomposition ofsewage.

The rate of biodegradation can also be increasedby planting vegetation in the area. Bacteria andfungi are more likely to inhabit soil where plantsare present.

Practice Questions: 2, 31, 32

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C.3.3 comprehend information on the biological

impacts ofhazardous chemicals on localand global environments, by:

• interpreting evidencefor environmentalchanges in the vicinity of a substancerelease

• interpreting LD50 data and otherinformation on toxicity

• identifying concerns with the disposal ofdomestic wastes, such as paints andoils, and industrial wastes

IMPACTS OF HAZARDOUS CHEMICALS

It is important to properly dispose of hazardouschemicals. Even a small amount of a chemical

released into the environment can have detrimentaleffects. The harmful effects of a toxin orhazardous chemical often increase throughbiomagnification as it moves through the foodchain. For example, if a small quantity of mercuryleaked into a lake, it would be absorbed byphytoplankton. Small fish that feed on thephytoplankton might absorb some toxins from thewater, but they would also take in all the mercurythat the phytoplankton had absorbed. Since onefish would eat many phytoplankton, the mercuryconcentration would be many times higher in thefish than in the phytoplankton. The mercury levelwould be magnified again when larger fish eat thesmaller fish. An osprey that then eats the largerfish would have the highest concentration ofmercury.

Certain chemical substances, such as householdcleaners, fertilizers, pesticides, paints,and automotive fuels, are hazardous to yourhealth. If not handled properly, they can be toxic.

The use of pesticides and the combination ofpesticides can produce poisoning effects.This is referred to as the chemical's toxicity.Toxicity describes how poisonous a substance is.

To compare the toxicity of certain chemicals,scientists use a measurement called themedian lethal dose or LD50. The LD5o is the doseof a toxic substance required to kill half themembers of a tested population after a specifiedtest duration.

For example, the LDS„ dosage of DDT in rats is87 mg/kg. Half the rats in a population k}-ould dieif given a dosage of 87 mg /kg of DDT.

Practice Questions: 33, 36

C.3.4 describe and evaluate methods used totransport, store, and dispose of hazardoushousehold chemicals

C.3.5 investigate and evaluate potentialrisks resulting from consumerpractices and industrial processes,and identify processes used in providinginformation and setting standards tomanage these risks

TRANSPORT, STORAGE, AND DISPOSAL

OF HAZARDOUS CHEMICALS

Students working inlaboratories must befamiliar with theWorkplace HazardousMaterial InformationSystem (WHMIS).WHMIS labels oncontainers specify thetype of hazardouschemicals in thecontainers. The barrels in the illustration containflammable chemicals.

Material Safety Data Sheets (MSDS) give detaileddescriptions of chemical products. An MSDScontains information about the composition,physical properties, and chemical features of thechemical product. It describes the precautions tobe taken while handling, storing, transporting, ordisposing of that product.

Chemicals are not just found in a laboratory.Many chemicals are found at home.Cleaners, fertilizers, pesticides, paints, andautomotive fuels are hazardous to human healthand they can be toxic if not handled properly.

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When storing hazardous chemicals, be sure to takethe following precautions:

• Leave products in their original containers withtheir labels intact.

• Keep the chemicals out of the reach of children.

• Keep containers tightly closed with a lid.

• Store chemicals in a cool, dry place.

• Do not store flammable liquids in glasscontainers.

• Store corrosive, flammable, reactive, andpoisonous chemicals separately.

• Keep oxidizers (such as hydrogen peroxide,H202(I)) away from flammable chemicals.

• Return chemicals to their proper locationsafter use.

• Safely discard hazardous chemicals if theyhave expired.

Hazardous chemicals should not be poured downthe drain, into sewers, into septic systems, or intothe soil. Do not throw chemicals in the garbage.There are hazardous waste collection sites wherewastes such as oil, paints, and household cleanerscan be disposed of. It is very important totransport, store, and dispose of hazardouschemicals properly.

Practice Questions: 35, 37

C.3.6 identify and evaluate information andevidence related to an issue in whichenvironmental chemistry plays amajor role

ENmoNMEENTAL CHEMISTRY

Environmental chemistry is the study of thechemical processes in an environment..Environmental chemists study which chemicalsare present naturally in an ecosystem, theirconcentrations, and their effects on the naturalenvironment. Understanding environmentalchemistry is an important first step towardsunderstanding how a clean environment works andhow pollutants change things.

Environmental chemistry is used by EnvironmentCanada and environmental research bodies aroundthe world in order to identify the source ofpollutants and their potential polluting impacts onthe environment.

Practice Question: NR2

r

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PRACTICE QUESTIONS-ENVIRONMENTAL CHEMISTRY

Use the following information to answerthe next question.

Inorganic minerals are necessary for the growthof the human body.

1. Which two inorganic elements are found in thecomposition of bones and teeth?A. Iron and sulfur

B. Sulfur and chlorine

C. Sodium and potassium

D. Calcium and phosphorus

2. In most sewage treatment processes, there is astage at which the waste is broken down bybacteria. The fact that this waste can bebroken down by bacteria indicates that thewaste isA. biodegradable

B. organic

C. nontoxic

D. natural

3. Certain types of bacteria present in the roots oflegume plants are responsible forA. nitrogen fixation

B. cleaning up the soil

C. decomposing dead matter

D. replenishing phosphorus in the soil

Use the following information to answerthe next question.

In order to carry out certain life activitiesefficiently, living organisms need somenutrients in small quantities (micronutrients)and other nutrients in relatively large amounts(macronutrients).

4. Which of the following elements is not amacronutrient?

A. Calcium

B. Fluorine

C. Nitrogen

D. Phosphorus

5. The most abundant food type that plantsprovide for human consumption isA. carbohydrates

B. proteins

C. oils

D. fats

6. Which of the following organic compoundsfound in living organisms are responsiblefor heredity?A. Fats

B. Proteins

C. Nucleic acids

D. Carbohydrates

7. The organic substances containing carbon,hydrogen, and nitrogen that are responsible forthe growth and repair of worn-out tissues areA. carbohydrates

B. nucleic acids

C. proteins

D. lipids

THE KEY - Science 9

81 Environmental Chemistry

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8. Which of the following substances is not agaseous air pollutant?A. Nitrogen oxide

B. Hydrogen sulfide

C. Sulfur dioxide

D. Carbon

9. Wastewater from kitchens, bathrooms, andlaundries is treated in sewage treatment plants.The treated water is called

A. household wastewater

B. disinfected water

C. effluent

D. sewage

10. Solid hazardous wastes are destroyed inA. septic tanks

B. incinerators

C. sanitary landfills

D. sewage treatment plants

11. The process that uses energy to move nutrientsfrom an area of low concentration to an area ofhigh concentration is calledA. osmosis

B. diffusion

C. capillary action

D. active transport

Use the following information to answerthe next question.

The chemical breakdown of starch into sugaroccurs in the mouth. This reaction uses waterpresent in the saliva.

12. A chemical reaction that requires water tobreak down large molecules into smallermolecules is called

A. ingestion

B. oxidation

C. hydrolysis

D. electrolysis

13. Roots of plants absorb water from the soilthrough the process of

A. passive transport

B. active transport

C. absorption

D. osmosis

14. The pesticide DDT was used in the 1940's tocontrol mosquito levels and reduce malaria.While it was effective as an insecticide it alsocontaminated lakes and streams and ended upin the food chain. Which of the followingstatements about DDT is most likely false?A. DDT levels increased in fish through

bioaccumulation

B. DDT levels increased in fish eatingfalcons through biomagnification

C. DDT levels increased in lake weedsthrough biomagnification.

D. DDT levels increased in fish eatingfalcons through bioaccumulation

Practice Questions

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Use the following information to answerthe next question.

The construction of a new fertilizer plant hasbeen approved of for Rapid City, but manycitizens are worried about environmental issuesthat could arise. Citizens were asked to providequestions to the mayor about their concerns.

Questions Asked by the Citizens

1. How will the plant affect the smell ofthe air?

2. Will the chemicals be diluted before beingreleased into the environment?

3. Will either the products or by-products stayin the environment?

4. Will the construction of the plant improvethe local economy?

15. The questions related to environmental issuesare indicated by the numbersA. 1, 2, and 4

B. 1, 2, and 3

C. 1, 3, and 4

D. 2, 3, and 4

16. Occasionally, raw sewage is dumped directlyinto a lake or river. The major effect that thishas on the water environment is that theA. oxygen content of the water drops

B. aquatic plant growth decreases

C. water becomes poisoned

D. bacteria die

17. Lichens are organisms that can be found evenin the Arctic and on the highest mountains.The substrate on which lichens grow isA. rock

B. snow

C. water

D. polyps

18. Which of the following biological indicators isleast likely to be used to determine the qualityof water in a lake?A. Leeches

B. Ducks

C. Frogs

D. Fish

19. Acid rain is any precipitation that has a pHlower thanA. 4.9

B. 5.2

C. 5.6

D. 7.2

Use the following information to answerthe next question.

The oxygen content ofthe atmosphere isapproximately 21 %, andthe oxygen concentrationof typical lake water isabout 0.001%.

20. Which of the following rows identifies theconcentrations of oxygen in the atmosphereand lake water in ppm?

Row

Oxygen inAtmosphere

(ppm)

Oxygen in LakeWater(PPm)

A. 210 000 10

B. 21 0.001

C. 21000 000 1 000

D. 21>1 106 1x103

THE KEY - Science 9

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Use the following information to answerthe next question.

Before investigating animal life in a pond, yourefer to your field manual and find the followinginformation.

Oxygen Requirements of SomeFreshwater Invertebrates

OXYGENCONCENTRATION ORGANISMS

(mglL) PRESENT

• large variety of8 and above invertebrates (insect(excellent level) larvae of many

kinds, worms, etc)

• a few mayfly larvae

• some stonefly larvae

6 (good level) • many midge larvae

• many worms,including leeches

• many midge larvae

4 (critical level) . many worms,including leeches

• many midge larvae

2 (low level) • some worms,including leeches

less than 2 • some midge larvae

(very low level) • some worms

21. You collect water samples from the pond andfind more midge larvae than mayfly larvae.You infer that the oxygen concentration in thispond is most likely.A. 6 mg/L

B. 4 mg/L

C. 2 mg/L

D. less than 2 mg/L

Saw". PAT, 1999

22. A solution was made by dissolving 3 mL offood colouring in 997 mL of water. In thissolution, the concentration of food colouring isA. 18 ppm

B. 300 ppm

C. 1 800 ppm

D. 3 000 ppm

23. On the pH scale, neutral is indicated bythe number

A. 0

B. 1

C. 5

D. 7

Use the following information to answerthe next question.

Properties

1. Tastes sour

2. Tastes bitter

3. Does not dissolve in water

4. Dissolves in water

5. pH less than 7

6. pH greater than 7

7. Turns litmus paper blue

8. Turns litmus paper red

Numerical Response

a The properties of acids given in the chart,listed in ascending numerical order, are

. (Record youranswer as a four-digit number.)

Practice Questions

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Use the following information to answerthe next question.

To study the effects of the campsite on the soil,you collected soil samples from four differentsites in the camp area before the camp was setup, during the project, and after the campsitewas removed. This chart shows the data youcollected.

pH Level

Site Before During After

1 7.6 7.2 6.6

2 7.8 7.5 6.9

3 7.5 7.4 7.4

4 7.4 6.9 6.5

24. You conclude that the activities at thecampsite caused the soil to become

A. neutral

B. more basic

C. more acidic

D. polluted. P!T JV'.

Use the following information to unstrwrthe nest question.

A scientist wanted to know which one of threecities received the most acidic rain. The

scientist conducted the following experiment.

1. A 50 mL sample of rain from each city wascarefully measured.

II. A base was added to each sample, one dropat a time.

III. The number of drops of base required tobring each sample to pH 7 was counted.

25. What type of reaction did the scientist performto test for acidity?

A. Oxidation

B. Reduction

C. Equalization

D. Neutralization

Use the following information to answerthe next question.

Frank was testing a sample of an unknown acidic

liquid in science class. Frank accidentally spiiitdsome of the liquid on his hand.

26. The first thing Frank should do after spillingthe liquid is

A. put a neutralizing agent on his hand

B. dry his hand on his pants

C. leave his wet hand to air dry

D. rinse his hand in water

27. Which of the following phenomena is aneffect of acid rain?

A. Global warming

B. Depletion of ozone layer

C. Increase in the pH of soil

D. Decrease in the pH of bodies of water

28. Airborne pollutants are generally transportedeastward in Alberta as a result of the

A. prevailing westerly winds

B. location of the Rocky Mountains

C. rotation of Earth in a 24-hour period

D. small amounts of snowfall and rainfall

THE KEY - Science 9

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29. The tiny spaces between soil particles throughwhich water flows are calledA. holes

B. pores

C. membranes

D. contaminants

30. Water that soaks through the soil and carriesdissolved substances into the soil is calledA. filtrate

B. leachate

C. acid rain

D. contaminant

31. Which of the following rows providesan example of biodegradable andnon-biodegradable material, respectively?

Row BiodegradableNon-

biodegradable

A. Wood Plastic

B. Metal Paper

C. Water Oil

D. Styrofoam Rock

32. Organic waste can be broken down through aprocess calledA. biotechnology

B. biodegradation

C. bioaccumulation

D. biomagnification

Use the following information to answerthe next question.

Treated waste water from the workers' housingis discharged into a river. A delegate interestedin water quality wants to know more about the

impact of the waste water on the river system.The tar sands representative shows the delegatethe results of a study in which water sampleswere collected from six different sites along theriver.

The oxygen concentration for each sample wasdetermined and the following chart was made.

SiteNumber

OxygenConcentration (mg/L)

1 12.0

2 12.5

3 8.0

4 3.5

5 2.0

6 5.0

33. Based on this data, the delegate inferred thatimmediately downstream from the workers'housing the treated waste water dischargedA. had no effect on the quality of river water

B. added toxic chemicals to the river water

C. improved the abiotic conditions of theriver water

D. decreased the concentration of oxygen ofthe river water

Source PAT 1999

Practice Questions

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34. The increase in the amount of harmfulsubstances at each trophic level of the foodchain is called

A. biomagnifcation

B. biodegradation

C. intensification

D. concentration

35. Which of the following diagrams representsthe WHMIS symbol for compressed gas?

of36. The LD50 is the standard used to compare

the toxicity of substances. LD5a means that

A. 50 animals would die if they consumed adose of the toxic substance

B. 50% of animals would die if theyconsumed a dose of the toxic substance

C. 50% of the test population of animalswould die if they consumed a specificdose of the toxic substance

D. 50% of the test population of animalswould die if they consumed any amount ofthe toxic substance

37. An MSDS provides all the followinginformation about a product except

A. the product's composition

B. methods of use for the product

C. the product's chemical features

D. precautions for handling and storingthe product

Use the following information to answerthe next question.

Many human activities negatively affect wakequality. Four human activities are given.

1. A coal-burning factory, which emits sulfurdioxide, is built near a river.

2. A logging company cuts down most of thetrees close to a river.

3. Cattle manure is dumped near a river.

4. Raw sewage is accidentally dumped intoa river.

!Numerical Response

Match each of the given human activitieswith the effect it would have on the river.

Decrease in Decrease in Increase in Increase inoxygen

pH of the phosphate sediment inlevels

water

levels

the water

(Record your answer as a four-digitnumber.)

A.

B.

C.

D.

THE KEY -- Science 9 87 Environmental Chemistry

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ANSWERS AND SOLUTIONS-PRACTICE QUESTIONS

1.D

9.C

17.A

2. A

10. B

18. B

3.A

11.D

19.C

4.B

12.C

20.A

5. A

13. D

21. A

6.C

14.C

22.D

7.C

15.B

23.D

8. D 16. A

NR1. 1458

24. C

32. B

25.D

33.D

26. D

34. A

27. D

35. A

28. A

36. C

29. B

37. B

30. B

NR2. 4132

31. A

1. D

Bones and teeth are made up of the salts of calciumand phosphorus. That is why nutritionists suggestdrinking milk. Milk contains calcium.

2. A

Biodegradable means that the substance can bebroken down or decomposed by microorganisms.

3. A

Certain types of bacteria present in the roots oflegume plants are responsible for nitrogen fixation.These bacteria are able to convert atmosphericnitrogen to useful nitrates in the root nodules.The bacteria and the root nodules have a symbioticassociation. Both the bacteria and the plantsbenefit from the relationship.

4. B

Fluorine is not a macronutrient. Nutrients thatare required for the growth and development ofplants in a considerably high amount are calledmacronutrients. Examples are nitrogen,phosphorus, and potassium. Only smallquantities of fluorine are required, so it is nota macronutrient.

5. A

Human nutrition depends directly or indirectly onplants. Plants carry out a process calledphotosynthesis. As a result, plants synthesizecarbohydrates, which are then consumed as foodby living organisms, including humans.

6. C

Nucleic acids include DNA and RNA.These organic compounds are found in the cells ofliving organisms and are responsible for heredity.Deoxyribonucleic acid and ribonucleic acid are themost complex organic compounds present in thecells of living organisms and are responsiblefor the transmission of characteristics to thenext generation.

7. C

Proteins are organic compounds containing carbon,hydrogen, and nitrogen. Proteins are synthesizedin your body. They are responsible for the growthand repair of worn-out tissues.

8. D

Carbon is a solid. It is an element that is part of allliving things. However, carbon compounds likecarbon monoxide and carbon dioxide are gases thatcan be air pollutants.

Answers and Solutions

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9. C

Wastewater is treated in a sewage treatment plantand the treated water is called effluent.Effluent is nearly 99% pure water.

10. B

Solid hazardous wastes are destroyed inincinerators. Sanitary landfills, sewage treatmentplants, or septic tanks are not able to remove thesehazardous wastes.

11. D

In active transport, energy is used to movenutrients from an area of low concentration to anarea of high concentration. Roots acquire mineralsfrom the soil through active transport.

12. C

Hydrolysis is a chemical reaction in which achemical compound is broken down when wateris added. Maltose sugar and water createglucose sugar.

13. D

Roots of plants absorb water from the soil throughthe process of osmosis. Osmosis occurs through aselectively permeable membrane. It is specific towater. Water molecules from the soil diffuse intothe cells of roots through the cell membranes ofroot hairs.

14. C

The biomagnification of DDT or other chemicalsoccurs in higher trophic levels. Lake weeds are inthe first trophic level as producers.

15. B

The issues relating to the environment are the smellof the air, the release of chemicals into the air, andwhether or not the chemicals will remain in theenvironment.

16. A

Raw sewage in the water will be decomposed bybacteria. The decomposition uses oxygen and willdeplete the oxygen level in the water.

17. A

Lichens grow on rocks, hence their substrate isrocks. Lichens obtain nutrients from this substrate.

18. B

A species that is used to monitor the health of alake ecosystem is called an indicator species.Different aquatic systems can use differentorganisms to estimate water quality. The mostcommon organisms used are leeches, amphibians,and fish. Birds are rarely used as an indicatorspecies, although in certain aquatic systems, birdpopulations can reflect changes in water quality.

19. C

Any precipitation that has a pH lower than 5.6 isacidic. Various gases such as sulfur dioxide andnitrogen dioxide dissolve in water droplets to makethe rainwater acidic.

20. A

Compare the % ration to a ppm ratio.

Oxygen in Oxygen in LakeAtmosphere Water

21

.r 0.001 _

x-1001000000 100

1 000000x=210 000 ppm x=10 ppm

21. A

The most likely level of oxygen concentrationis 6 mg/L or higher. At levels below 6 mg/L, thechart indicates that no mayfly larvae are present.

THE KEY - Science 9

89 Solutions - Environmental Chemistry

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22. D

The unit ppm means parts per million.It is calculated as follows:

The total volume of the solution is 1000mL.(3 mL food colouring + 997 mL solution= 1 000 ML)

3 mL:I 000 mL =x:l 000 0003 mL x l 000 000

X

1 000 mL= 3 000 ppm

23. D

On the pH scale, lower than 7 indicates that thesubstance is acidic and higher than 7 means that itis basic. A neutral substance is neither acidic norbasic and has a pH of 7.

NR 1 1458

Acids taste sour (1), dissolve easily in water (4),have a pH of less than 7 (5), and cause litmus paperto turn red (8).

24. C

The pH scale expresses how acidic or basic asubstance is. The lower the pH is, the more acidicthe substance. The higher the pH is, the more basicthe substance. A drop in pH means that thesubstance becomes more acidic. There was a dropin pH at every site. The activities must havecaused the soil to become more acidic.

25. D

The scientist determined the degree of acidity byneutralizing the acidic water with a base.

26. D

The unknown acidic liquid is potentiallyhazardous. In order to be completely safe,Frank should dilute the substance to the greatestextent possible. Using a neutralizing agent is not agood idea since the liquid has unknown properties.

27. D

Rain that contains strong acids dissolved in wateris called acid rain. The pH of acid rain is low.When acid rain falls into surface bodies of watersuch as lakes and ponds, it lowers their pH.Global warming is mainly caused by greenhousegases such as carbon dioxide and water vapourpresent in the atmosphere. Ozone layer depletionis mainly caused by chlorofluorocarbons (CFCs).Acid rain can lower the pH of soil. Soil can beseriously damaged by acid rain. However, acidrain cannot increase the pH of soil.

28. A

Pollutants are spread through the air by windcurrents. In Alberta, the westerly winds areresponsible for the eastward movementof pollutants.

29. B

Pores are the tiny spaces between soil particlesthrough which water flows. Ground water seepsthrough the tiny spaces between soil particles.

30. B

Water that soaks through the soil and carriesdissolved substances into the soil is called leachate.This leachate percolates through the small spacesin the soil called pores.

31. A

Organic matter is composed of living or once-living matter. Organic matter is almost alwaysbiodegradable. Wood is biodegradable-it can be decomposed by bacteria. Some plasticscan be decomposed by bacteria, but this happensso slowly that plastic can be considerednon-biodegradable. Often, plastic will remainunchanged in the envirorunent for many years.

32. B

Biodegradation is a process whereby bacteriapresent in the soil decompose waste products andbreak down complex molecules into simplesubstances.

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33. D

Based on the data, the delegate inferred thatimmediately downstream from the workers'housing, the treated wastewater decreased theconcentration of oxygen of the river water.

34. A

Biomagnification is the increase in the amount ofharmful substances in each trophic level of thefood chain. The harmful substances accumulate inthe body of one organism and pass to the organismthat eats it. Thus the amount of the substanceincreases at each level.

35. A

The symbol with a cylinder inside a circlerepresents compressed gas. Compressed gas isstored in cylinders.

36. C

The LDsu is the standard parameter used tocompare the toxicity of substances. It means thatwhen a specific dose of a toxic substance isadministered to a test population, 50% of the testpopulation will die. Generally, these tests fortoxicity are carried out on rats or mice.

37. B

An MSDS does not provide information about themethods of use. It gives detailed descriptions ofthe product, including its composition and itschemical and physical features. It also describeshow to use the product safely.

NR 2 4132

4. Raw Sewage dumped directly into a river wouldresult in an increase in the number of bacterianeeded to decompose the sewage, which wouldlower the oxygen levels.

1. Sulfur dioxide from the coal-burning factorywould combine with water in the air to make acid,which would fall to the ground as rain or snow.The acidic moisture would eventually make its wayinto the river through runoff or ground water.

3. As the cattle manure was decomposed bybacteria, the phosphate that was in the manurewould be released, and it would wash into the river.

2. Removing trees close to the river would exposethe soil to weather elements. Heavy rains wouldcause the soil to erode into the river.

THE KEY - Science 9

91

Solutions - Environmental Chemistry

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UNIT TEST-ENVIRONMENTAL CHEMISTRY

Use the following information to answerthe next question.

1. Which of the following elements would not beconsidered a nutrient in a bag of fertilizer?A. nitrogen

B. carbon

C. phosphorus

D. potassium

2. Nitrogen in the air is released in a form thatcan chemically combine to make other usablecompounds. This process is usuallyaccomplished by bacteria and is referred to asA. decomposition

B. conversion

C. fixation

D. uptake

3. Toxic nicotine has an LDs0 of 0.86 mg/kg.In a test sample of 1 200 rats, how manywould survive this dosage?A. 50

B. 220

C. 600

D. 1 200

4. Rapid City has a pollution problem resultingfrom the large number of motor vehicles usedin the city. Which chemical equationrepresents the pollutant causing this pollutionproblem?

A. 6CO2 + 6H20 -> C6H1206 + 602

B. 2NO2 + H2O - HNO3 + HN02

C. 4Fe + 302 - 2Fe2O3

D. 2H2+02-+2H20

5. A shipment of hydrochloric acid comes with aMaterials Safety Data Sheet (MSDS).Which of the following pieces of informationwould not be found on the MSDS forhydrochloric acid?

A. Source of the material

B. Precautions to be taken

C. A list of physical properties

D. A description of the composition

Use the following information to answerthe next question.

An organic vegetable grower notices an aphidproblem that may affect his crop production.However, he is also concerned aboutenvironmental pollution.

6. What method of pest control is he most likelyto use?A. Spraying with herbicides

B. Fertilizing with micronutrients

C. Introducing biological predators

D. Watering with enzyme nutrients

Unit Test

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Use the following diagram to answerthe next question.

7. Which of the following pollutants would mostsignificantly affect the ground water aquiferin the given diagram?

A. Leachate seepage from the nearby landfill

B. Discharge of effluent into an overflowpond

C. Regular use of fertilizer during cropseeding

D. Sulfur dioxide acid rain emission from thesteel factory

Use the following information to answerthe next three questions.

ewngetreatment

plant

Rustic City

`B

RusrPR..

O CUitirgtedI l ++!t 'l̂arrtf aa ,,

Seed crop(wheal)

8. A sample of water was collected and tested atsite E. It was found to have a concentration ofpesticides that measured 0.055 mg/100 mL.How many ppm is this equivalent to?

A. 5.5

B. 55

C. 550

D. 5 500

Use the following additional information toanswer the next question.

Another test was conducted at each of the fivesites to determine the amount of suspendedparticles present in the water at each site.The data collected was graphed, as shown.

3000900

800

a. 600

500400300

y

200--too..

A B C D E

Site

9. A possible explanation for the high amount ofsuspended particles at site D is

A. erosion of the cultivated land

B. aerial spraying of the wheat crop

C. irrigation of the vegetable garden

D. improper garbage disposal in theparks area

.

93THE KEY - Science 9 Environmental Chemistry

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Use the following additional information toanswer the next question.

_

The water at each of the sites was also tested foracidity. Some of the testing was done usinglitmus paper. Other testing was done using apH probe.

Red Blue pHSite Litmus Litmus Reading

A turns no changeblue

B no no change

change

C 6.8

D no turns redchange

E 7.6

10. Which of the following rows identifies howmany sites were acidic, basic, or neutral?

Row Acidic Basic Neutral

A. 2 2 1

B. 1 3 1

C. 2 1 2

D. 3 1 1

11. Mucor, a saprophytic fungus, grows ondecaying food material. Mucor obtains itsnutrition from

A. tree bark

B. bread

C. rocks

D. water

12. Which of the following statements about waterquality is false?

A. In the summer, the water in a lakebecomes cloudy and oxygen contentis reduced.

B. Trout are bioindicators of oxygen contentin water.

C. The clarity of the water indicates that thewater is free from pollution.

D. The presence of excessive numbers ofbacteria in water may be harmful to otherorganisms.

Use the following information to answerthe next question.

Frank was testing a sample of a liquid inscience class. When a piece of blue litmuspaper was placed into the liquid, the litmuspaper turned red.

13. The liquid was most likelyA. basic

B. acidic

C. a pollutant

D. a salt solution

Use the following information to answerthe next question.

DDT is a pesticide that farmers used to spray ontheir crops to ward off insects. Unfortunately,once DDT is released into the environment, itdoes not break down. Because of this, DDT canspread as shown in the given example.

crop -+ grasshopper -+ small bird -+ falcon

14. In this example, as the DDT passes along thefood chain, the concentration of DDT wouldA. decrease then increase

B. gradually decrease

C. gradually increase

D. remain the same

Unit Test

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r

Not for Reproduction

Use the following information to answerthe next question.

The diversity of living organisms in a body of

water is affected by the condition of the water.The condition of water can change over time.Scientists studying a particular pond overseveral years recorded changes in the waterconditions, as shown in the given chart.

Condition Changed From Changed TopH 4.5 6.5

Phosphate 8 mg/L 10 mg/LcontentDissolved

g mg/L 2 mg/Loxygen

Suspendedparticles 12 mg/L 2 mg/L

Indicate with a number 1 if the change incondition would have increased thebiodiversity of organisms and a number 2 ifthe change would have decreased thebiodiversity of organisms.

Written Res onse

Use a simple food chain example to explainthe concept of biomagnification.

(2 marks)

Use a concept map to compare the beneficialand harmful aspects of ozone.

(2 marks)

1q-

0

pH

Phosphate Dissolved Suspendedcontent

oxygen

particles

(Record your answer as a four-digitnumber.)

Use the following information to answerthe next question.

Pollutant

1. Acid rain

2. Leachate

3. Insecticide

4. Excessive phosphate

Match each of the given pollutants with itspossible source.

Sewage

Vehicles

Fruit

Garbagepond

orchard

dump(Record your answer as a four-digitnumber.)

THE KEY - Science 9 95

Environmental Chemistry

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ANSWERS AND SOLUTIONS-UNIT TEST

WR1. See Solution

WR2. See Solution

1. B

5. A

9. A

2. C

6. C

10. A

3.C

7.D

11.B

4. B

8. C

12. C

13. B

14. C

NR1. 1221

NR2. 4132

1. B

All of the elements except carbon are consideredplant nutrients and are found in most fertilizers.The main source of carbon in plants comes fromthe carbon dioxide in the air.

2. C

Nitrogen fixation is the process of changing freenitrogen into nitrogen compounds that organismscan use. For example, certain bacteria located inthe nodules of beans can separate nitrogen gas intofree nitrogen, which then combines with otherelements to form compounds such as protein.

3. C

LD stands for lethal dose. The number 50 standsfor 50%. When a dose of 0. 86 mg/kg is given tothe test sample of rats, half will die. This meansthat 600 rats will survive.

4. B

Equation A represents photosynthesis bygreen plants.

Equation C represents the rusting or corrosionof iron.

Equation D represents the electrolysis of water.

All of these are natural processes and do notcontribute to the pollution problem.

Equation B represents the production of acid rainfrom the release of nitrogen oxide compounds.

5. A

Composition, properties, and precautions are

indicated on an MSDS. Directions for use willvary with each activity.

6. C

An organic grower would shy away from sprayingwith chemicals. Instead, he may introducebiological predators such as ladybugs to feed onthe aphids.

7. D

An impermeable layer of rock prevents pollutantsand waste material from seeping into the aquifer.Leachate from the farm, landfill, and overflowpond will be stopped by the first layer of rock.The sulfur dioxide emissions from the steel factorywill mix with rain and create acid rain, which canenter the aquifer between the two layers ofimpermeable rocks.

The unit ppm stands for parts per million. Solve bysetting up a ratio.0.055

x100 1 000 000

x=550

Water erosion, and perhaps wind erosion, from thecultivated field along Tobee Creek and Rust Riverwould result in more particles suspended in thewater at site D.

8. C

9. A

Answers and Solutions

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10. A

Red litmus turns blue in a base. Blue litmus turnsred in an acid. A pH of 7 is neutral. A pH higherthan 7 is basic. A pH less than 7 is acidic.

Site Result

A Basic

B Neutral

C Acidic

D Acidic

E Basic

Mucor is a saprophytic fungus that grows ondecaying food. It obtains nutrition from itssubstrate. When bread is kept in a moist, warmplace, the spores of the fungus fall onto the breadand start to grow.

The clarity of water does not indicate that the wateris free from pollution because clear water maycontain bacteria or some dissolved pollutants.

The liquid was most likely acidic since it turnedblue litmus paper red.

NR 1 1221

A pH increase to 6.5 indicates that the waterquality is becoming less acidic (more organisms).An increase in phosphate content means more plantdecay and less oxygen (fewer organisms). A dropin the oxygen content results in fewer survivingorganisms. A reduction in the suspended particlesmeans clearer water with more organisms.

NR 2 4132

High nitrogen oxide emissions from vehicleexhaust cause acid rain. Leachate from the garbagematerial may seep into the ground water system.Insecticides can be used to control insect pests infruit orchards. High nitrogen and phosphatecontent in a sewage pond may reduce the amountof oxygen available for organisms.

Use a simple food chain example to explain theconcept ofbiomagn f cation.

Biomagnification refers to the increase inconcentration of a chemical as it moves upthrough the food chain.

In a food chain such asgrass -* grasshopper -+ snake, the amountof chemical present in the snake wouldaccumulate from the grass and the grasshopper.The concentration would be greatest in thesnake and the least in the grass.

Use a concept map to compare the beneficial andharmful aspects of ozone,

11. B

12. C

13. B

0

0

14. COzone Gas

Ground level ozonecauses asthma and

respiratory diseases.

Because toxic substances that bioaccumulatebecome part of the tissues of an organism's body,they will be passed on when the organism is eaten.As these compounds are passed up through eachtrophic level, they accumulate in greaterconcentrations in the organisms of higher trophiclevels. This process is called biomagnification.

A layer of ozoneprotects Earth from

large amounts ofultraviolet rays.

I

THE KEY - Science 9

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Solutions - Environmental Chemistry