Soil and acid precipitation

1. Soil and acid precipitation Soil is what sustains plants. Plants are what sustains ecosystems

2. What is Soil?

3. Soil… • It is more than just dirt!! • Soil has many life forms within it, and this life is crucial for the health of the ecosystem it is in. • Soil is a loose covering over the ground that contains organic matter, minerals (rocks), and moisture. • To assess soil quality, we must look at • Soil profile • Soil Type • Acidity

4. Soil Profile There are three distinct layers to the composition of soil: 1) Topsoil – O and A layers. It is composed mostly of humus, which is decaying organic matter. It has rocks and many organisms like bacteria, fungi, insects and worms. 2) Subsoil – B layer It is very compact and has little or no organic matter except roots of very large trees and bacteria 3) Regolith and bedrock – C and R layers The regolith is composed of large chunks of rock, and the bedrock is solid rock. Water cannot pass through bedrock, so it pools here. This is where aquifers (groundwater) are located.

5. Volume composition of a desirable surface soil 45 to 48% mineral matter 50% pore space 25% air 50% solid material 25% water 2 to 5% organic matter Not all soil has this balance – only the most desirable soil. For example, C layer soil is mostly mineral matter. It has little water and air, and no organic matter.

6. Soil Particles • All soil originated from bedrock, therefore all soil is made up minerals (weathered rock) • The weathered rock is known as soil particles. The soil particles are classified from largest to smallest as sand, silt, and clay

7. Types of Soil 1) Sand: • Relatively large particles • Feels coarse and gritty • Creates large spaces that permit root growth and air pockets for plants • Water drains too easily, taking nutrients away from roots of plants

8. Types of Soil 2) Silt: • Fine particles, a muddy texture • Easily transported by water, so it is found in and along rivers and wetlands • Soil drains slowly, so it facilitates plant growth. However, the soil also erodes easily. • Human activities such as logging and bad farming practices result in unwanted silt being washed into rivers, which is a pollutant

9. Types of Soil 3) Clay: • Very fine particles • Particles are packed tight together, so there are no air pockets. It is dense. • Clay traps water so it is often very wet and sticky. • Plant growth is difficult.

10. Types of Soil 4) Loam • Has rock particles of different sizes (sand, silt, and clay) and pockets that hold air or water • Has lots of humus • Drains well without drying out • Plants grow easily • Has a dark brown or black colour

11. Types of Soil • Which soil type do you think is best for agriculture?

12. Human Impacts on Soil • Soil Erosion: The loss of soil when water or wind blows it away. • This occurs when soil is ploughed or tilled and the topsoil is exposed to wind and water which causes it to erode. • Occurs due to overgrazing by livestock or too much ploughing for farming • If the top soil is gone, the nutrients are gone.

13. Human Impacts on Soil • Fertilization: The process of a farmer adding extra nutrients to the soil to make plants grow bigger and faster • Without fertilizers, many farmers would not be able to grow as much food • Manure is a natural fertilizer • Artificial fertilizers are common nowadays – they are synthetic chemical compounds of nitrogen, phosphorus, etc. • This fertilizers wash away from the soil and pollute local water bodies. It results in excessive algae growth (eutrophication).

14. Human Impacts on Soil • Leaching: The process by which soil receives a lot of water, and the nutrients in the topsoil wash downward, making them unavailable to plants. • In wet environments, such as rainforests, this occurs naturally. This is why rainforests are not good for farming. • When humans overly water soils, nutrients are leached from the topsoil. Sandy soil gets leached easily. Why is this?

15. Humans Impacts on Soil • Crop Rotation: The practice of planting a different crop in a field each year. This is good for the soil. • This replenished the nutrients in soil • Crops such as legumes, help put nitrogen in the soil since they have nitrogen-fixing bacteria • If crops are not rotated, the nutrients in the soil get used up and crops will no longer grow well.

16. Acidity of Soil • Acidity is another factor in soil quality • We use the pH scale to assess the acidity level of soil

17. Acidity of Soil • If soil has a low pH (0-7) it is considered acidic • If soil has a high pH (7-14) it is considered alkaline • Most plants and organisms prefer a neutral environment • If soil is too acidic or alkaline it can harm plants: • The roots that absorb the plants’ nutrients are damaged • The waxy coating on plants’ leaves that prevents it from infection is damaged • However, some plants do require slightly acidic or alkaline pH levels • Earthworms in the soil are also harmed because their skin gets burned • You will also have an opportunity to do you Soil Lab ISU on acidity

18. Acid Precipitation • Acidic soil is the result of Acid Precipitation • Acid precipitation describes any form of rain or snow with high levels of nitric and sulfuric acids. • It is 40 times more acidic than normal rain • When humans burn fossil fuels, sulfur dioxide and nitrogen oxidesare released into the atmosphere, whichreact with water, oxygen, and other substances to form mild solutions of sulfuric and nitric acid.

20. Sources of Acid Precipitation • Emissions come from coal burning plants, cars, metal smelters and oil refineries • However, Cars are the biggest cause of acid rain by burning fuels • Although countries have emission standards on cars there are more and more cars being driven.

21. A forest affected by acid precipitation

22. Aquatic Impacts • In addition to soil, acid precipitation affects aquatic ecosystems: lakes, streams, wetlands, and other aquatic environments • Acid rain makes waters acidic and causes them to absorb the aluminum that makes its way from soil into lakes and streams. This combination makes waters toxic to crayfish, clams, fish, and other aquatic animals. • Shellfish are particularly sensitive because the acid dissolves their shell

23. Action on Acid Precipitation • When scientists discovered the damaging effects of acid precipitation, governments put limits of emissions • Factories have installed scrubbers in their smoke stacks, which remove a large proportion of the damaging chemicals from the emissions before they’re released into the air • Acid precipitation has been reduced, but countries that have not implemented emission standards continue to produce pollution – which is carried by wind. Therefore, acid precipitation is a global problem.

24. Homework Read pages 70-75 Soil • Page 75 #1-5 • Page 85 #3, 13, 14 Acid Precipitation • Page 85 #11, 15, 16