2.2 ASSESSING THE IMPACT OF HUMAN ACTIVITIES ON ECOSYSTEMS (1) pp

The Impact of Human Pollution  The United Nations Environment Programme (UNEP) estimates that plastic debris kills more than a million sea birds every year.  Sea birds, sea turtles, and other animals mistake bits of plastic for food items.  Plastic pieces can last for over 50 years in the ocean

Acid Rain and Ontario’s Ecosystems  Emissions from a variety of human activities contain pollutants that enter the atmosphere and can have wide-ranging effects on the environment.

Acid Rain and Ontario’s Ecosystems  Nitrogen- and sulphur-containing substances are two of the most common pollutants in emissions  They combine with water vapour in the air and form acids.  The acids formed in the air by emissions fall as acid rain.  Acid rain affects soils, vegetation, lakes, rivers, and terrestrial and aquatic animals.

Effects of Acid Rain  Destroys coatings on leaves  Infection  Burns some organisms skin  Increases soil acidity - plants cannot absorb nutrients as well.  Increases acidity of bodies of water.  Can dissolve Shellfish shells  Acid lakes contain no life  Government Response  Mining companies installed scrubbers  Reduced emissions

Effects of Acid Rain

Assessing Impacts on Ecosystems Assessing Soils  Soil - is a loose covering on the ground containing a mixture of organic matter, minerals, and moisture. Soil quality has 3 parts. 1. Soil Profile  Topsoil is the uppermost layer in soil.  Contains Humus – decaying organic matter Rock particles Bacteria, fungi, insects and worms.

Assessing Soils  Subsoil is the layer below topsoil.  Little or no organic matter except roots of very large trees and bacteria.  Bedrock forms the bottom of the soil profile.  solid rock  Water sits above it  The top surface of ground water is called the water table.

Assessing Soils

2. Soil Types  Loam soil  Most fertile  Loose, Contains air and water  Contains lots of humus  Good for growing plants Agriculture

2. Soil Types  Clay Soil  Packed tightly  Few air pockets  Traps water  Little growth  Sandy Soil  contains sand particles  Contains air pockets  Drains easily, looses nutrients easily  Not as fertile as loam, better than clay.

Soil Types

3. Acidity Levels  Acidity is an abiotic factor that is connected to the chemical environment of soil. Soils vary in their acidity  To precisely assess acidity levels in soil, a special scale is used. The pH scale

3. Acidity Levels  The pH of a soil can be measured by testing the moisture in the soil with specially treated strips of paper that change colour depending on the pH.  High pH = Alkaline  Most organisms prefer neutral soil.

3. Acidity Levels  pH Scale

Human Impacts on Soils  Soil erosion is the loss of soil when water or wind washes or blows it away.  The roots of plants normally hold the topsoil in place. When soil is ploughed, or tilled, the topsoil is exposed to wind and water, which can erode it. Overgrazing by livestock animals, such as cows and sheep, can also erode the soil.

Human Impacts on Soils  If the same type of crop is grown in the same soil year after year, the nutrients in the soil get used up, and the crops no longer grow well in the soil.  Crop rotation is the practice of planting a different type of crop in a particular field each year.

Human Impacts on Soils

 Plants of the legume family, such as soybeans, peas, lentils, and alfalfa, have a symbiotic relationship with nitrogen-fixing bacteria. By planting nitrogen-fixing plants, the nitrogen in the soil gets replenished.  If farmers do not rotate their crops, they have to supply nutrients to the soil by adding fertilizers.

Homework  Read pp. 68 – 75  Answer p. 75 # 1 – 5