Human Effects On Soil, Water and Air
In this slideshow... We will examine: • Humans and the environment • Human effects on soil • Farms • Forests • Brownfields • Human effects on water
Humans and the Environment It's clear that humans harm the planet in many ways. We can reduce the harm, but as the human population rises, the problems keep getting worse. This next video is all about the population problem.
Imagine the world as an apple... This is the amount of surface that would be available for farming.
Soil Crops can only be grown on about 12% of the land on earth. The soil we have on earth cannot keep up with the demand for food as the population of humans on earth increases. Just 9% of Canada is farmland.
What is Soil? Soil consists of: • Organic matter • Mineral content • Air • Water
Growth of Cities As the populations of cities grow, they need more and more land for houses and other buildings. Cities were originally founded near the best soil for farming. This means, we often build on or pave over the best, most fertile soil.
Canada's Best Topsoil Here is a picture of some of Canada's best topsoil.
Farming Technology Fortunately, the output from our farms continues to increase because of increased farming technology. (Unfortunately, the use of chemicals causes other problems).
Erosion Erosion naturally occurs on the planet, but human development has increased it. First, let's look at what erosion is.
Soil Erosion Soil can be eroded by wind or water. If unprotected, our planet's precious topsoil can be blown or washed away. Farmers have to be very careful to make sure that topsoil stays where it is.
Soil Erosion In this quick video, you can see the top soil being washed away by the rain.
Clear Cutting We need many wood products in our lives, but the practice of clear cutting is still common in many areas and severely damages the soil and ecosystems of the area.
Clear Cutting Trees hold the soil together, so when forests are clear cut they can have massive erosion problems. Often logging, mining and manufacturing leave behind chemicals that harm the environments they are in. These are often difficult to remove; they can affect all life that lives near them.
Brownfields Large chunks of polluted land, abandoned by industries are called Brownfields. Once the industry has moved out or went out of business, cities are often left to clean up the mess. Many times they are just left unused since clean up of the soil is too expensive.
Brownfields in Brantford, ON Unless cleaned up, nothing can be built here.
Water Human activity causes incredible harm to our water systems. There are many paths for contaminants to take to get into our water. Figure 1.16 pg.13
Drinking Water Without proper care of our waste, drinking water can become contaminated and unhealthy to drink. This is a very serious problem in poor countries.
Garbage Island Since plastic will not biodegrade, it stays around for a long time. When a plastic bottle is dumped into a river, it eventually makes its way to the ocean. It will join garbage island.
Garbage Island After many years of plastics making their way into our oceans, there is now a giant patch of plastic in the Pacific Ocean bigger than Texas.
Air Before looking at how humans can damage the air, let's look at how fantastic our atmosphere is.
Fossil Fuels Most of the damage we do to our air comes from the use of fossil fuels that we use for driving, heating, manufacturing and generating electricity. They include: gasoline, natural gas, oil, propane, diesel fuel, heating oil and coal.
Fossil Fuels When fossil fuels are burned, they release molecules into the air. Some of these are natural, others are toxic. Some such as carbon dioxide is completely normal in the atmosphere, but too much is a problem. We will come back to this.
Smog Some of these molecules that are released in the air create smog: a haze of mostly ozone (O3) made when hydrocarbons and nitrogen oxides combined with heat from the sun.
Smog The picture below shows the difference between smog a hot day without wind, and a cooler day with wind.
Smog Smog is the disastrous result of too much exhaust from fossil fuels being emitted close to large city centres. It is such a problem now, that air quality information is included in the weather report. It's called the Air Quality Index. Smog causes 5,900 early deaths in Canada every year.
Smog How does smog affect our health? Health effects of smog may include: • eye, nose and throat irritation • coughing and wheezing • worsening of symptoms for people who have lung diseases like asthma and COPD • difficulty breathing • reduced lung capacity • lowered resistance to infections • increased heart and lung conditions • increases in visits to emergency room and hospital admissions • premature death http://www.lung.ca/protect-protegez/pollution-pollution/outdoor-exterior/smog-smog_e.php
Acid Precipitation Acid Precipitation is rain and snow that has pH values below 5.6 When CO2 and NO2 rise in the air they can dissolve into the vapour in clouds creating sulfuric and nitric acids. These acids come down with the rain.
Global Warming Global Warming refers to the average annual (yearly) increase in global temperatures that has occurred since around 1850.
Review Questions Describe 2 ways human activities can cause topsoil to be damaged Many corn farmers leave the stalks of the corn in the ground after the corn has been harvested. Give one reason why this is a good method of helping to conserve topsoil. What is the difference between water and wind erosion? Give 2 examples of living things that can be impacted by acid precipitation.