Environmental Science Interactions (SVN3E)
Answers to Questions
Safety in the Laboratory
CYU pg. ix
1. ammonia aqueous, aqua ammonia, ammonia TS
2. ammonia 31%, water 69%
3. Hazards include destruction of mucous membrane and upper respiratory tract tissues, and death. Symptoms may include a sensation of burning, coughing, wheezing, laryngitis, shortness of breath, headache, nausea, and vomiting.
4. Immediately flush the eyes with plenty of water for at least 15 minutes while occasionally lifting and lowering the upper eyelids. Get immediate medical attention.
5. Do not make the person vomit. Instead, if conscious, ask the person to drink large quantities of water.
6. Chronic exposure is prolonged or repeated exposure to a hazard.
Unit A Human Health
Section 1.1
CYU pg. 6
1. Porosity means that soil has pore spaces for air and water. Air contains oxygen that plant roots need to live. Water dissolves nutrients that plants also need to live. Plants also need water for photosynthesis. Without roots, plants cannot get enough water or nutrients.
2. Water is considered a universal solvent because so many other substances will dissolve in it.
3. Surface water is water on land, as found in lakes, ponds, and rivers. Ground water is water that has percolated into soil or rock below Earth’s surface.
CYU pg. 7
1. No. Air is a mixture of gases. The most abundant gas, at 78.1% by volume, is nitrogen (N2). Oxygen (O2), at 20.9% by volume, is the second most abundant gas.
2. They take it in in the form of ions such as ammonium (NH4+) or nitrate (NO3+). Special bacteria that live in the roots of legumes like peas and beans create these ions. Lightning can also create nitrates. These nitrates are carried to Earth in precipitation.
1.1 Review Questions pg. 9
1. Soil is the land on which we live. It is a mixture of minerals, organic matter, air, and water that can often support plant growth. Water is a simple compound of hydrogen and oxygen that can dissolve many different substances. It forms lakes, rivers, oceans, and underground deposits. Air is a mixture of gases that lies above the soil and water.
2. Soil contains pore spaces that hold air and water. Water covers some soils and often carries soil particles. It also usually has dissolved air in solution. Air often carries soil particles in the wind and contains dissolved water vapour.
3. All the spheres are equally important. Plants, for instance, need soil, water, and carbon dioxide and oxygen from the air to live. Animals also need carbon dioxide and oxygen from the air, as well as water. They also need carbohydrates from plants, and so also depend on soil.
4.
5. Organic matter rots to make humus, which helps soil to hold water. This water helps provide plants with the nitrogen, phosphorus, and potassium that they need.
6. Pitcher plants grow in peat, or soils containing more than 20% organic matter. These soils hold a lot of water. The bog soil must therefore be very wet and have an organic content of 20% or more.
7. Likely not. The mineral content of a sandy beach soil would be very high and the organic content very low. Furthermore, being so close to a lake, the water content of the soil just below the surface would likely be high and the air content low. Most plant roots would not survive these conditions.
8. An atom becomes an ion when it loses or gains an electron and so becomes electrically charged. The process is called ionization. Table salt (NaCl), for instance, is comprised of one sodium ion (Na+) and one chlorine (Cl−) ion.
9. Hydrogen ions (H+) dissolved in water; b. acidic
Hydroxide ions (OH−) dissolved in water; c. alkaline
Equal number of H+ and OH− ions; a. neutral
10. No. A pH of 7 means that the liquid is neutral and has an equal number of H+ and OH− ions.
11. For example,
Gas / Candy equivalentSulphur dioxide (SO2) / 1
Ozone (O3) / 100
Carbon monoxide (CO) / 500
Nitrous oxide (N2O) / 2500
Methane (CH4) / 10 000
Carbon dioxide (CO2) / 180 000 000
Water vapour (H2O) / 0—20 000 000 000
Oxygen (O2) / 104 500 000 000
Nitrogen (N2) / 390 500 000 000
12. Carbon dioxide and oxygen are constantly recycled from the atmosphere into living plants and animals and then back to the atmosphere after they die. This is called the carbon cycle.
Plants make carbohydrates and oxygen by using energy from sunlight to combine carbon dioxide from the atmosphere with water. Animals eat these carbohydrates or other animals that eat them. Animals combine carbohydrates with oxygen from the atmosphere to get the energy they need. In this process of cellular respiration, they exhale carbon dioxide and water. So the carbon dioxide exhaled by a dinosaur millions of years ago may indeed make up part of the carbon found in your body today.
CYU pg. 12
1. about 12%
2. about 26%
3. For example, unused paint and paint thinner poured down a drain pipe can pollute water supplies.
4. Fertilizer is spread on agricultural land and dissolved by precipitation. Some dissolved fertilizer runs off into surface water like lakes and rivers. This water eventually drains into the ocean, carrying some of the dissolved fertilizer with it.
CYU pg. 15
1. Acid precipitation is rain or snow with a pH below 5.6. Precipitation with pH values above this level is considered regular precipitation.
2. sulphuric and nitric acids
3. Greenhouse gases (GHGs) absorb the sun’s heat and keep part of the heat reflected off Earth’s surface from leaving. Instead this heat is re-radiated back to Earth. As more and more GHGs are produced, more heat is created and re-radiated back to Earth. This creates a steady rise in temperature.
1.2 Review Questions pg. 17
1. It can be lost by being mixed up with other soil components. It can also paved over for roads and sidewalks.
2. The roots of the corn stalks help to hold the topsoil in place and prevent erosion.
3. Water erosion is caused by water running down the slope of the land. Farmers can help prevent water erosion by ploughing their fields at 90° to the slope of the land. Wind erosion is caused by loose particles of soil carried away by strong winds. Farmers can help to prevent wind erosion by planting windbreaks between fields.
4. Two reasons we cut down trees are to make lumber and pulp for paper.
5. The new housing development would disturb soil and likely cause soil runoff into nearby streams. Some of this runoff would include silt that could settle out on spawning areas and destroy them.
6. Gasoline, oil, and other toxic substances are frequently spilled on streets, while road salt is applied after snow storms. Large amounts of these substances are washed into storm drains after heavy rains. When the drains empty directly into a nearby river or lake, living things are affected by the toxic substances.
7. clams, crayfish, and fish; trees and other plants
8. steadily increasing amounts of greenhouse gases resulting from the steadily increasing use of fossil fuel
9. No. Greenhouse gases play an essential role in making sure that some of the heat that falls on Earth from the sun is retained to warm our atmosphere and surface.
10.
11. an average, annual increase in global temperature; more frequent and severe droughts and floods and melting polar ice caps
CYU pg. 19
1. A soil horizon is a layer of soil that has distinct proportions of soil components. There are five different horizons.
2. A horizon soil is dark, loose, and rich in humus. It is also known as topsoil. B horizon soil is lighter coloured and denser than A horizon soil. It has little organic content.
3. The soil is tested for components such as phosphorus, potassium, magnesium, and nitrogen. The soil’s pH is also measured. The results help farmers to decide how to make their soil more fertile, and the type of crops that will grow best in it.
CYU pg. 22
1. A weight and long rope are attached to one end of a flexible plastic pipe about two metres long. While holding onto the rope, the weighted, lower end is lowered into the water body. Care is taken not to let the lower end touch the lake, river, or reservoir bottom. With the pipe about two metres under water, the top of the pipe is capped and the lower end is pulled to the surface. The water sample inside the pipe can then be tested.
2. Microbiological test sampling determines whether there are coliform and E. coli bacteria in drinking water. The presence of these bacteria may mean that the water is contaminated.
3. Turbid water looks cloudy because there is suspended matter in it.
1.3 Review Questions pg. 27
1. She could apply agricultural lime to her soil to make it less acidic.
2. The soil on his farm is generally good. However, the medium colour means that he might want to add more organic matter such as manure and compost. He might also want to lower his soil pH to below 7.4.
3. erosion; low levels of organic matter
4. Cover crops protect the soil from erosion and shade it for the organisms that live in it.
5. The contents of the sample become mixed up when removed from the water.
6. nitrates; lead
7. Hard water is softened by adding sodium to the water piped into homes.
8. Stack sampling is used to detect these chemicals. Probes are attached to sample lines. The probes remove some of the gas from the stack, and send it to a computer to analyse the pollutants.
9. Fine particulate matter is so small that it can be inhaled into the lungs, causing special problems for people with asthma or other respiratory problems.
10. They rate the air quality on an index from 0 – 15 (very good, no health effects expected in healthy persons) to 100 and over (very poor, with serious effects on people with heart/lung disorders).
11. One could take public transit instead of driving; use less energy in their home; not mow the lawn.
Unit A Human Health
Section 2.1
CYU pg. 31
1. Water, carbon, nitrogen, phosphorus, and sulphur are cycled through ecosystems.
CYU pg. 34
1. Biosolids can be used to revive eroded soils and as fertilizer for crop soils.
2. Biosolids have been buried in landfills, burned as fuel, and dumped into the oceans. Generally these are not good means of disposal.
2.1 Review Questions pg. 35
1. Producers are plants and some bacteria that make their own food by photosynthesis or chemical means. Consumers are plants and animals that need to eat other animals and plants to get the energy that they need to grow, live, and reproduce.
2. In an ecosystem, producer and consumer wastes and dead producers and consumers are broken down or decomposed by fungi and bacteria. The chemical products can then be used by living producers.
3. Livestock waste can release large amounts of ammonium into soil. This can cause excess amounts of nitrogen to enter freshwater streams and lakes. The excess nitrogen can be toxic to aquatic organisms, cause plants to grow too quickly and become weak, and reduce the amount of oxygen in the water and the ability of aquatic organisms to reproduce.
Certain farming practices can also strip nitrates, phosphates, and organic matter from the soil. This causes soil erosion and acidic soils.
4. Natural ecosystems rely on decomposers to recycle all the substances in their systems. All the substances in these systems are biodegradable. Human-activity systems do not have efficient decomposers, and the goods people make are often not biodegradable.
5. Results will vary. Check to be sure that students have drawn and labelled appropriate examples of producers, consumers, and decomposers. For example, a producer might be a grain farmer, a consumer a person who eats cereal and bread, and a decomposer a compost bin or operation.
6. If not properly processed, biosolids may contain pathogens and toxic wastes. Even when “clean”, too great a quantity of biosolids applied to a soil may harm plant growth and affect ground water and aquatic systems downstream.
Section 2.2
CYU pg. 37
1. Carbon sinks like forests remove and store carbon dioxide from the air and release oxygen through the process of photosynthesis. When forests are cut down or burned they become carbon sources because the carbon dioxide stored in their tissues is released back to the air.
2. One tonne of carbon dioxide equivalents represents the mass of a GHG that would give the same warming level over 100 years as one tonne of carbon dioxide.
CYU pg. 38
1. Three activities that contribute to one’s primary carbon footprint are the GHG emissions from the burning of fossil fuels for heat, electricity, and transportation. Three activities that contribute to one’s secondary carbon footprint are the GHG emissions used to produce the food one eats and the products and services that one uses.
CYU pg. 40
1. Because they have two or more power sources, hybrid vehicles are generally more fuel efficient than internal combustion engine vehicles. The electric batteries in hybrid vehicles can also store energy and then reuse it in stop-and-go traffic.
2. Living in a rich, developed country means that many Canadians can own their own houses and drive one or more cars. We can also afford to fly places more often and buy more things than people in poorer countries like Egypt.
2.2 Review Questions pg. 43
1. GHGs differ in their capacity for trapping heat from the sun in Earth’s atmosphere. Using the same unit of carbon dioxide equivalents allows the different warming effects of different GHGs to be combined into one measurement.
2. a. 100 Gt CO2e ÷ 40.8 GtCO2e = 2.45; 2.45 × 1.4 GtCO2e/40.8 GtCO2e = 3.43 Gt CO2e/100 Gt CO2e.
b. 24.7 Gt CO2e × 2.45 = 60.51Gt CO2e/100 Gt CO2e; 50% of 60.51 = 30.255Gt CO2e.
c. 5.6 Gt CO2e × 2.45 = 13.72Gt CO2e/100 Gt CO2e; 13.72 × 3 = 41.16 Gt CO2e.
3. An understanding of carbon footprints allows us to see how we affect the creation of greenhouse gases through our activities and our choices as consumers.
4. For example, the costs to manufacture, to transport, and to dispose of the bottle and its cap and label are not included.
5. a. gas, oil, and coal, electricity, private transport, public transport, and holiday flights
b. food and drink, clothes and personal effects, carbon in car manufacture, household (building and furnishings), recreation and leisure, financial services, and share of public services
6. A hybrid vehicle uses two or more different power sources, one of which is often an electric motor. An internal combustion vehicle uses only an internal combustion engine as its power source. Hybrid vehicles are usually more fuel efficient.
7. For example,
8. Planes burn larger amounts of fossil fuel per distance travelled. Also, planes that fly at high altitudes burn even more fuel.
9. For example, I could wash my clothes in cold water and hang them outside to dry, use a microwave whenever possible instead of a conventional oven or stove, and shut off unused lights when I leave a room.
10. Carbon offsets are emission reduction credits that are bought to make up for GHG emissions put into the air. The carbon offsets are used to financially support projects like renewable energy developments that significantly lessen GHGs.
11. Carbon offsets support projects that result in fewer GHGs. However, buying carbon offsets may not encourage people or industries to first lower their own carbon footprints.
12. They can pass laws to force industries, municipalities, and provinces to eliminate or significantly reduce their use of fossil fuels.
Section 2.3
CYU pg. 46
1.a. Plants like kelp and sea grasses that live in tidal zones can be coated with oil and die.
b. Mammals can be smothered by oil or be poisoned after ingesting it, with death a frequent result. The insulating ability of mammal fur may also be lost, meaning that affected animals may freeze to death.
c. Birds can also be smothered by oil or the insulating ability of their feathers lost, with death again a frequent result. Oil also damages the structure of feathers and makes it difficult for birds to float and fly. Breathing in oil vapours can also affect birds’ nervous systems, livers, and lungs.
CYU pg. 48
1. It means that the lake has become acidified as the result of acid precipitation falling on the lake and rivers that drain into it.
2. First, acid precipitation adds hydrogen ions to the soil. This leaches alkaline nutrients like calcium and magnesium from the soil. Trees need these nutrients and may stop growing and die without them. Second, acid precipitation increases the level of heavy metals such as aluminum in the soil. Aluminum can be toxic to plants, fish, birds, and soil organisms. Third, acid precipitation increases the amount of sulphur and nitrogen in soils. Excess nitrogen can leach into surface water and affect nearby soil and plants.
2.3 Review Questions pg. 51
1. Oil enters ecosystems accidentally when oil tankers and ships run aground, become disabled, or sink. One way that oil enters an ecosystem intentionally is when a tanker ship’s tanks are cleaned to remove oil residue. Another way is when oil is intentionally dumped on land.
2. Check student illustrations to be sure they properly represent the proportional relationships between the relative volumes. Students may wish to represent the relative volumes in litres or as the number of living rooms, classrooms, houses, school gyms, or other appropriate volumetric unit such as Olympic swimming pools.
3. 568
4. An oil slick is a thin layer of oil floating on top of water. A tar ball is formed after an oil spill when the lighter substances in the oil evaporate and the heavier components combine with oxygen and sink. These eventually wash up on shore as tar balls.