Unit C Lesson 1: Human Activities and Chemical Changes in the Environment
Completion requirements
Unit C Lesson 1: Human Activities and Chemical Changes in the Environment |
Learning Targets |
Big Question: What human activities cause chemical changes in the environment?
Humans have a large amount of influence over the types and amounts of chemicals found in the environment.
Humans have a large amount of influence over the types and amounts of chemicals found in the environment.
At the end of this inquiry, you should be able to answer the following questions:
- Why is the nitrogen cycle important?
- What is nitrogen fixation?
- Why are pesticides used?
- What is leachate and hose is it produced in a landfill?
- What is fuel combustion?
- What is sour gas?
Pages 182 to 187 in your textbook will help you answer these questions about human activities and chemical changes in the environment.
Introduction
Chemicals
are the basic building blocks that make up all living and non-living things on Earth.
All organisms require chemicals to survive. In Lesson 2 in the Chemistry unit, you learned about elements and compounds. A chemical is considered to be any element or compound that has a constant chemical composition. Chemicals are found everywhere around us. Examples of some household chemicals would be water, gold, salt, sugar, and plastic.
Certain chemicals are beneficial. For example, some trees contain chemicals that produce medicine to treat illness such as malaria and cancer. Other chemicals are dangerous such as the toxins produced in a nuclear explosion.
Lesson 1 has two parts:
All organisms require chemicals to survive. In Lesson 2 in the Chemistry unit, you learned about elements and compounds. A chemical is considered to be any element or compound that has a constant chemical composition. Chemicals are found everywhere around us. Examples of some household chemicals would be water, gold, salt, sugar, and plastic.
Certain chemicals are beneficial. For example, some trees contain chemicals that produce medicine to treat illness such as malaria and cancer. Other chemicals are dangerous such as the toxins produced in a nuclear explosion.
Lesson 1 has two parts:
- The Nitrogen Cycle
- Human activities that Affect the Environment
The Nitrogen Cycle
Chemicals in the environment are changing form constantly.
In Science 7, you learned about how carbon is the building block of all living organisms. Carbon atoms are never created or destroyed; however, carbon is reused through the carbon cycle. In this section, you will discover how nitrogen is recycled through the nitrogen cycle.
Chemicals in the environment are changing form constantly.
In Science 7, you learned about how carbon is the building block of all living organisms. Carbon atoms are never created or destroyed; however, carbon is reused through the carbon cycle. In this section, you will discover how nitrogen is recycled through the nitrogen cycle.
Read pages 184 to 185 in Science in Action 9 to learn more about the nitrogen cycle.
Nitrogen is an important element to humans because our bodies are composed of 3% nitrogen. Nitrogen is a required nutrient for the body to form proteins. Without proteins, your cells would lack enough nourishment to repair muscles and to
build new tissues.
Nitrogen gas or free nitrogen, N2(g), makes up 78% of the air around us. Plants, animals, and humans are unable to use nitrogen from the air. How is free nitrogen made available to plants and animals?
Nitrogen gas or free nitrogen, N2(g), makes up 78% of the air around us. Plants, animals, and humans are unable to use nitrogen from the air. How is free nitrogen made available to plants and animals?
Nitrogen fixation
is the process of combining free nitrogen with other elements to produce nitrogen compounds that can be used by organisms. In a way, that is not yet completely understood, nitrogen-fixing bacteria in the
root nodules
of certain plants (such as beans, clover, and alfalfa) use nitrogen gas to make nitrogen compounds.
The enormous electrical energy of lightning breaks apart nitrogen molecules (N2) in the atmosphere and enables their atoms to combine with oxygen in the air, forming nitrogen oxides. These nitrogen oxides dissolve in rain, forming nitrates (a “useable” form of nitrogen), that are carried to the earth where it is broken down further by plants in the process of nitrogen fixation.
The enormous electrical energy of lightning breaks apart nitrogen molecules (N2) in the atmosphere and enables their atoms to combine with oxygen in the air, forming nitrogen oxides. These nitrogen oxides dissolve in rain, forming nitrates (a “useable” form of nitrogen), that are carried to the earth where it is broken down further by plants in the process of nitrogen fixation.
Watch
There is no question that this video, "Nitrogen Cycle", is odd. It is also informative and hopefully makes this important and complicated process easier to understand,
For a more traditional approach to learning about the nitrogen cycle, click here to open the NOVA video "Lightning Produces Nitrates" to
learn how lightning across the Earth produces essential nutrients for plant growth.
Nitrogen is made available to living organisms by a process called the nitrogen cycle.
The diagram in Figure 1 shows the steps in the nitrogen cycle:
- Nitrogen from the atmosphere falls to the ground through precipitation.
- Nitrogen in the soil is fixed by bacteria found in root nodules.
- These nitrogen compounds are absorbed by plants from the soil.
- When animals eat plants, they ingest the nitrogen compounds.
- Plant and animal waste return nitrogen to the soil with the help of decomposers.
- The nitrogen in the soil is released into the air or is used by plants.
Figure 1– The nitrogen cycle can be found in the air, water, soil, and most living things.
Interactive
The Nitrogen Cycle
-
The BrainPOP video, "Nitrogen Cycle", gives an excellent and easy explanation of the cycle. Click here to watch the video. After you watch the video,
try some of the other interactive activities on this page.
You will need a username and password to access the video.
- Username: 0099
- Password: students
- Click here to complete the quiz to test your knowledge of the Nitrogen Cycle.
How do human activities negatively affect the environment?
People throughout the world enjoy using materials made with plastics, modern transportation, and many amenities. To enjoy all these amenities requires the manufacturing and collecting of resources. Unfortunately, chemicals introduced to the environment through human activities can have a negative effect.
Read pages 186 to 187 in Science in Action 9 to learn more about human activities that have a negative impact on the environment.
The transportation of resources such as oil in ships can damage aquatic life and habitats seriously if an oil spill occurs.
Improper disposal of toxic material such as lead paint can poison plants, animals, and waterways.
Combustion of fossil fuels pollutes the air, which is used by plants and animals.
Human activities affect the air, water, and soil in the environment.
Fertilizers contain nitrogen, phosphorus, and potassium needed for healthy plant growth.
The label in Figure 2 displays three numbers (15-30-15) that indicate the percentage of nitrogen, phosphorus, and potassium compounds in the fertilizer. The fertilizer contains
Many people use fertilizers on their lawns and gardens, but few people consider the potential drawbacks of these fertilizers.
Fertilizers contain nitrogen, phosphorus, and potassium needed for healthy plant growth.
The label in Figure 2 displays three numbers (15-30-15) that indicate the percentage of nitrogen, phosphorus, and potassium compounds in the fertilizer. The fertilizer contains
- 2% nitrogen compounds (first number)
- 13% phosphorus compounds (second number)
- 0% potassium compounds (third number)
Many people use fertilizers on their lawns and gardens, but few people consider the potential drawbacks of these fertilizers.
Figure 2 – Bags of fertilizer show the ratio of nitrogen:phosphorous:potassium in the fertilizer.
A pesticide is any chemical that it used to kill pests.
Pesticides are used all over the world to protect various crops and in some cases to protect the health of people.
Without the use of pesticides, more than 50% of the world’s crops would be destroyed by pests. To protect people from the mosquito that carries malaria, DDT is sprayed in fields and on the walls of huts in many parts of the world. DDT was banned in most countries in 2006 because it causes health issues such as cancer. It was reintroduced in 2008 because malaria drastically increased when DDT was not used.
Pesticides are used all over the world to protect various crops and in some cases to protect the health of people.
Without the use of pesticides, more than 50% of the world’s crops would be destroyed by pests. To protect people from the mosquito that carries malaria, DDT is sprayed in fields and on the walls of huts in many parts of the world. DDT was banned in most countries in 2006 because it causes health issues such as cancer. It was reintroduced in 2008 because malaria drastically increased when DDT was not used.
How much garbage do you think your household produces in a day?
If you are an average Canadian, you are contributing nearly 2 kg a day (or 730 kg a year) of garbage that is carted off to landfills.
The production of wastes on our planet is increasing. The storage or disposal of these wastes — until they can be returned naturally to the environment — is a major issue.
In the 1970s, sanitary landfills were introduced. In sanitary landfills, waste is spread over a large area and then covered with soil to encourage the natural decomposition of the waste. Landfills now must be lined with compacted clay and plastic. A system of drainage pipes is put at the bottom of the landfill to remove the leachate from the landfill.
If you are an average Canadian, you are contributing nearly 2 kg a day (or 730 kg a year) of garbage that is carted off to landfills.
The production of wastes on our planet is increasing. The storage or disposal of these wastes — until they can be returned naturally to the environment — is a major issue.
In the 1970s, sanitary landfills were introduced. In sanitary landfills, waste is spread over a large area and then covered with soil to encourage the natural decomposition of the waste. Landfills now must be lined with compacted clay and plastic. A system of drainage pipes is put at the bottom of the landfill to remove the leachate from the landfill.
Landfill leachate is a toxic liquid cocktail that moves through or drains from a landfill. These harmful chemicals leak into the ground, threatening the water supply, but also they can evaporate into the air.
Watch
The video "How does a Modern Landfill Work" explains clearly the potential dangers of landfills.
Sewage, Fossil Fuels, and Natural Gas
Sewage is wastewater containing dissolved and undissolved materials from your kitchen, bathroom, and laundry.
If you live in a rural area, your sewage is stored in a septic tank, an underground container in which bacteria break down organic materials in sewage before the sewage moves into the soil. If you live in a city, your family’s sewage is sent to a sewage treatment plant that contains special equipment to treat wastes so that they can be disposed of safely. Effluent or treated wastewater is released into rivers and lakes.
Untreated wastewater that is unintentionally introduced into water systems causes water pollution.
Sewage is wastewater containing dissolved and undissolved materials from your kitchen, bathroom, and laundry.
If you live in a rural area, your sewage is stored in a septic tank, an underground container in which bacteria break down organic materials in sewage before the sewage moves into the soil. If you live in a city, your family’s sewage is sent to a sewage treatment plant that contains special equipment to treat wastes so that they can be disposed of safely. Effluent or treated wastewater is released into rivers and lakes.
Untreated wastewater that is unintentionally introduced into water systems causes water pollution.
Fossil fuels are natural substances made from the remains of ancient plants and animals.
Fuel combustion is a chemical reaction in which fuel is burned in the presence of oxygen. This reaction produces carbon dioxide and water and releases energy in the form of light and heat. In most cases, the fuel used is a hydrocarbon that reacts with oxygen in the air.
The general reaction for the burning of fuel is
fuel + oxygen → carbon dioxide + water
Section 2 in this unit discusses how burning fossil fuels contribute to air pollution.
Fuel combustion is a chemical reaction in which fuel is burned in the presence of oxygen. This reaction produces carbon dioxide and water and releases energy in the form of light and heat. In most cases, the fuel used is a hydrocarbon that reacts with oxygen in the air.
The general reaction for the burning of fuel is
fuel + oxygen → carbon dioxide + water
Section 2 in this unit discusses how burning fossil fuels contribute to air pollution.
Natural gas, the cleanest burning of the fossil fuels, is an important fossil fuel used in generating electricity.
The combustion of natural gas releases fewer pollutants than the combustion of other fossil fuels. Natural gas contains methane, ethane, propane, and butane as well as some impurities.
Sour gas, which is extremely dangerous, is natural gas that contains a poisonous chemical called hydrogen sulfide (the pungent-smelling gas similar in smell to rotten eggs).
Sweet gas is natural gas that contains little or no hydrogen sulfide.
The combustion of natural gas releases fewer pollutants than the combustion of other fossil fuels. Natural gas contains methane, ethane, propane, and butane as well as some impurities.
Sour gas, which is extremely dangerous, is natural gas that contains a poisonous chemical called hydrogen sulfide (the pungent-smelling gas similar in smell to rotten eggs).
Sweet gas is natural gas that contains little or no hydrogen sulfide.