Human Impact on the environment

KA 5 Success Criteria I can state that increasing human populations require increased food yield I can explain the impact of using fertilisers can have in freshwater ecosystems I can describe how pesticides can accumulate in a food chain and its effects. I can state some examples of indicator species and state how their presence or absence indicate environmental quality/levels of pollution. I can explain how GM crops may be an alternative to the use of fertilisers and biological control may be an alternative to the use of pesticides.

Learning Intentions I can: state that increasing human populations require increased food yield explain the impact of using fertilisers can have in freshwater ecosystems

Ways of increasing food yield What does intensive farming mean to you?

Chicken battery farm Discuss the reasons why farmers keep their animals confined in small spaces

Pig battery farm

Monocultures Discuss with pupils what they think a monoculture is?

Advantages Crop is grown to soil type and climate Machinery used so labour costs are low and speeds up planting and harvesting More than one harvest a year. All have increased crop yield.

Agriculture tend to grow monocultures Monoculture: one plant species grown over a large area. Grown to increase food yield for growing human population. (Add to glossary) In a meadow consisting of a variety of plant species normal competition will control pests and weeds. Problems In a monoculture, you have to control hungry pests and weeds artificially. (PESTICIDES , FUNGICIDES and HERBICIDES) Over time the same plant grown in the same area will deplete the soil of nutrients, therefore you need fertiliser.

Main Disadvantages Large risk of disease as crops genetically identical. Increased risk of pests and damage to crops due to the close planting. Large scale use of fertilisers and potential for pollution problems. Machinery compacts soil so less oxygen available to crops. Decrease crop yield Hedgerows removed to increase field size but reduces biodiversity.

Fancy a swim? – Where has all that algae come from?

Algae block out the light and prevent green plants below the surface getting enough light for photosynthesis. When the algae die they become organic waste (just like sewage) and provide food for micro-organisms (bacteria). Bacteria feed on the algae and reproduce causing an increase in numbers. The increased numbers of bacteria use up more oxygen in respiration and reduce the oxygen available to other organisms. As a result many water organisms die and the number of different species decreases. i.e. biodiversity decreases.

Can you explain why all these fish have died?

To get an excellent presentation of the process of Eutrophication click here

Less availability of oxygen for other organisms!!! Aquatic plant and algae die eaten by increasing numbers of bacteria Large quantities of oxygen used up by bacteria Algal bloom decreases Light level Fertilisers leach into freshwater increases Algal blooms Do past paper Q10c on page 40 Less availability of oxygen for other organisms!!! Do specimen paper Q10c on page 40

L.I To describe ways of increasing crop yield without fertilisers. Prior KU Negative Impact fertilisers have on a fresh water ecosystem. State the process that occurs when excess fertiliser leaches into freshwater ecosystems Eutrophication Now add key word and definition to glossary

Reducing the problem caused by fertilisers Farmers could use natural fertilisers such as manure and compost to stop the risk of algal blooms. They could also use less fertilisers by using crop rotation. Use Genetically modified (GM) crops as an alternative. GM seeds may produce plants which can grow in lower concentrations of soil nitrogen or grow plants that require less water. S.C: I can explain how GM crops may be an alternative to the use of fertilisers Click above for clip on benefits of using GM seeds

learning intentions Name a pesticide which will not break down in the environment. Describe how pesticides can kill other organisms. Explain advantages of using biological control over pesticides.

Types of Pesticides These are chemicals sprayed onto crops to reduce competition from other organisms. Herbicide: kill _______________ Fungicide: kill ______________ Insecticide : to kill ____________ Bactericide : kill ______________

Research Activity DDT, a useful pesticide in 1945, was found to have lots of toxic effects on the environment, especially birds. DDT is not easily broken down by the environment. Bioaccumulation occurred in the top carnivores of a food chain Research the consequences of using DDT on birds. (Include your source from website and state why you think it is a reliable source.) Research Optional if time -write notes an appropriate title using information from slide to introduce what DDT is

Using Processing skills to explain bioaccumulation

Using Processing skills to explain bioaccumulation Each leaf receives one “dose” of DDT when sprayed. Each worm eats 3 leaves. Each robin eats 2 worms. Each sparrow hawk eats 2 robins. How many doses of DDT does the sparrow hawk eat?

12 2. If they eat enough DDT, birds lay eggs with very thin shells, which break before they are ready to hatch. How might this effect the sparrow hawk population, and the other members of the food chain?

Review of research Was the information you gathered relevant? Was your source reliable ? E.g. Information gathered was from a NAT 5 revision website which is an aid pupils use to improve their chances at performing well in the final exam. The information is at the appropriate level and linked to SQA mandatory knowledge. Wikipedia is not a reliable source as anyone can access the information and alter it.

Summary Pesticides sprayed onto crops can accumulate in the bodies of organisms over time. As they are passed along food chains toxicity increases and can reach lethal levels.

Biological control as an alternative to the use of pesticides The practice or process by which an undesirable organism is controlled by means of another (beneficial) organism. Ladybirds significantly reduces aphid (greenfly) numbers which would normally feed on the sap of the growing plant causing it to wilt.

Indicator species An indicator species if present or absent indicate environmental quality/levels of pollution.

Lichens Lichens are an indicator species which give information about the levels of sulphur dioxide pollution in the air Sulphur dioxide is a pollutant produced by the burning of fossil fuels such as coal, oil and gas

Level of pollution indicated Type of Lichen Level of pollution indicated Leafy Crusty Powdery None Draw a table with the following headings to show the different types of lichens and what level of pollution they indicate.

High sulphur dioxide pollution Indicator lichen type None

Low sulphur dioxide pollution Indicator lichen type Crusty

No sulphur dioxide pollution Indicator lichen type Leafy

Moderate sulphur dioxide pollution Indicator lichen type Powdery

An indicator species if present or absent indicate environmental quality/levels of pollution. (add to glossary) Several Indicator species can be used identify the levels of pollution in river

Sewage Works Direction of Flow Caddis Fly Larva Fresh Water Shrimp Stonefly Nymph Mayfly Nymph Stonefly Nymph Mayfly Nymph Sludge Worm Rat Tailed Maggot Water Louse Blood Worm Direction of Flow Very low levels of organic material Very low levels of Bacteria Very high levels of Oxygen Very high levels of organic material Very high levels of Bacteria Very low levels of Oxygen High levels of organic material High levels of Bacteria Low levels of Oxygen Low levels of organic material Low levels of Bacterial High levels of Oxygen Very low levels of organic material Very low levels of Bacteria Very high levels of Oxygen Task complete cut out work sheet with this slide

Testing river water samples Methylene blue dye tests for oxygen in water. The darker the colour, the more oxygen there is. Which of these tubes contains yeast? Lets test 2 samples A)unpolluted and C)polluted river water for oxygen availability Sample B) is the control Practical opportunity

Pollution & bacteria levels Analyse this graph and draw a valid conclusion.

Pollution & bacteria levels As the bacterial level increases the O2 level decreases because the bacteria use it up in respiration.

KA 5 Success Criteria I can state that increasing human populations require increased food yield I can explain the impact of using fertilisers can have in freshwater ecosystems I can describe how pesticides can accumulate in a food chain and its effects. I can state some examples of indicator species and state how their presence or absence indicate environmental quality/levels of pollution. I can explain how GM crops may be an alternative to the use of fertilisers and biological control may be an alternative to the use of pesticides.

N5: Revise key areas for Unit 3 Nab 1. Biodiversity and Ecosystems 2. Energy in Ecosystems 3. Sampling techniques and measurement of abiotic and biotic factors 4. Adaptation, natural selection and evolution of a species. 5. Human impact on the environment