Matter cycles  through the earth

1 oxygen cycle

The importance of oxygen

  1. Respiration – for plants and animals
  2. Combines with other elements to form  compounds that make up  rocks
  3. Oxygen in the the atmosphere is oxygen molecules  O2  and ozone  O3
  4. photosynthesis releases oxygen gas
  5. in the atmosphere Ultra Violet light (UV) decomposes water to form oxygen and hydrogen

2. Nitrogen cycle

Nitrogen is an important part of proteins and these are found in all living things. We get nitrogen from food so our bodies can make proteins and we can grow and function (proteins are in hormones, muscles etc). We can’t use Nitrogen directly from the air.

The cycle starts like this

  1. Nitrogen in the air is taken in by microbes in the soil – (nitrogen fixation)
  2. Nitrifying bacteria convert this to nitrites and then to nitrates.
  3. Plants take up the nitrates
  4. Animals eat the plants containing nitrates
  5. When both of these die or produce waste the nitrogen is returned to the soil by decomposers converting it to  ammonia  then back to a)

The Phosphorous cycle

Phosphorous is an important component of DNA and ATP ( the energy molecule found in all living things).  It’s a very slow cycle ( hundreds of years) phosphorous is essential for plant growth.

Summary of the cycle

  1. Rain weathers rocks and this washes phosphate ions into the soil
  2. Plants absorb phosphate, plants eaten by animals and phosphate gets into them.
  3. Phosphorous  returned to the soil in urine and faeces and when plants and animals die
  4. Sediments containing dead animals and plants can be turned into sedimentary rock

Fertiliser runoff promotes algal growth. This can reduce oxygen in the water and block sunlight reaching the other aquatic plants . This is eutrophication , it can result in massive fish kills – eg the minindi lakes.

5.4 The Water Cycle is a global cycle

The water cycle – see fig 5.11 for all the terms

Because the water cycle affects massive areas of the globe it also affects weather.  Evaporation in one ecosystem can lead to precipitation in another ecosystem thousands of miles away. When water vapour condenses it results in precipitation. This rain often runs off the surface of the earth and collects in rivers and lakes and eventually finding its way back to the sea.

Weather vs Climate

Weather is the day to day changes in temperature and rainfall. Climate is over a longer period.

The physics of weather

  1. Air heats up more closer to a hot surface ( eg the ground)
  2. Hot air rises. As it does so it becomes less dense. (low pressure
  3. The atmosphere gets cooler the further away for the ground you are. Cool air becomes more dense. (high pressure)
  4. Cool air sinks.
  5. Air (wind) travels from areas of high pressure to areas of low pressure.
  6. The terms; hot and cool, high pressure and low pressure, are relative.
  7. Isobars join places of equal pressure. When isobars are very close together the wind is stronger.
  8. Wind travels in an anticlockwise direction around a high pressure cell. Wind travels clockwise around a low pressure cell ( this is for the southern hemisphere)

5.4 Human activity affects the carbon cycle

a) the carbon cycle – geological – this occurs over thousands to millions of years. It is where carbon from living things is locked away in sediments. Some times these sediments turn into coal , oil or natural gas  (fossil Fuels)

b) the carbon cycle – biological/ physical – this is short term and occurs over days to years

A summary of the carbo cycle would include the processes of photosynthesis and respiration eg

  1. Plants take in Carbon dioxide and water and through photosynthesis turn them into sugars and oxygen.
  2. Oxygen is breathed in by animals and through cellular respiration they burn sugars in oxygen to produce energy + carbon dioxide + water.

How doers Carbon get into the atmosphere

  1.  respiration of living things
  2. Burning wood – bush fires, home heating etc
  3. Burning fossil fuels
  4. Volcanic eruptions

How can carbon be stored –(carbon sinks)

  1. In forests
  2. In the ocean
  3. In organic matter – coal, oil,gas
  4. Rocks – as carbonates (eg calcium carbonates like in limestone caves)
  5. Animal shells.

Human impact

Humans have affected the cycling of matter through nature.

  1. Reduced fish stocks by 90%
  2. Altering water runoff by building dams or diverting rivers, hydroelectric projects,
  3. Agriculture – clearing of vegetation, reducing biodiversity, pollution by over use of fertilisers or pesticides, soil degradation, overstocking of farm animals .

Use the power point to add to your notes

Matter cycles  through the earth

1 oxygen cycle

The importance of oxygen

  1. Respiration – for plants and animals
  2. Combines with other elements to form  compounds that make up  rocks
  3. Oxygen in the the atmosphere is oxygen molecules  O2  and ozone  O3
  4. photosynthesis releases oxygen gas
  5. in the atmosphere Ultra Violet light (UV) decomposes water to form oxygen and hydrogen

2. Nitrogen cycle

Nitrogen is an important part of proteins and these are found in all living things. We get nitrogen from food so our bodies can make proteins and we can grow and function (proteins are in hormones, muscles etc). We can’t use Nitrogen directly from the air.

The cycle starts like this

  1. Nitrogen in the air is taken in by microbes in the soil – (nitrogen fixation)
  2. Nitrifying bacteria convert this to nitrites and then to nitrates.
  3. Plants take up the nitrates
  4. Animals eat the plants containing nitrates
  5. When both of these die or produce waste the nitrogen is returned to the soil by decomposers converting it to  ammonia  then back to a)

The Phosphorous cycle

Phosphorous is an important component of DNA and ATP ( the energy molecule found in all living things).  It’s a very slow cycle ( hundreds of years) phosphorous is essential for plant growth.

Summary of the cycle

  1. Rain weathers rocks and this washes phosphate ions into the soil
  2. Plants absorb phosphate, plants eaten by animals and phosphate gets into them.
  3. Phosphorous  returned to the soil in urine and faeces and when plants and animals die
  4. Sediments containing dead animals and plants can be turned into sedimentary rock

Fertiliser runoff promotes algal growth. This can reduce oxygen in the water and block sunlight reaching the other aquatic plants . This is eutrophication , it can result in massive fish kills – eg the minindi lakes.

5.4 The Water Cycle is a global cycle

The water cycle – see fig 5.11 for all the terms

Because the water cycle affects massive areas of the globe it also affects weather.  Evaporation in one ecosystem can lead to precipitation in another ecosystem thousands of miles away. When water vapour condenses it results in precipitation. This rain often runs off the surface of the earth and collects in rivers and lakes and eventually finding its way back to the sea.

Weather vs Climate

Weather is the day to day changes in temperature and rainfall. Climate is over a longer period.

The physics of weather

  1. Air heats up more closer to a hot surface ( eg the ground)
  2. Hot air rises. As it does so it becomes less dense. (low pressure
  3. The atmosphere gets cooler the further away for the ground you are. Cool air becomes more dense. (high pressure)
  4. Cool air sinks.
  5. Air (wind) travels from areas of high pressure to areas of low pressure.
  6. The terms; hot and cool, high pressure and low pressure, are relative.
  7. Isobars join places of equal pressure. When isobars are very close together the wind is stronger.
  8. Wind travels in an anticlockwise direction around a high pressure cell. Wind travels clockwise around a low pressure cell ( this is for the southern hemisphere)

5.4 Human activity affects the carbon cycle

a) the carbon cycle – geological – this occurs over thousands to millions of years. It is where carbon from living things is locked away in sediments. Some times these sediments turn into coal , oil or natural gas  (fossil Fuels)

b) the carbon cycle – biological/ physical – this is short term and occurs over days to years

A summary of the carbo cycle would include the processes of photosynthesis and respiration eg

  1. Plants take in Carbon dioxide and water and through photosynthesis turn them into sugars and oxygen.
  2. Oxygen is breathed in by animals and through cellular respiration they burn sugars in oxygen to produce energy + carbon dioxide + water.

How doers Carbon get into the atmosphere

  1.  respiration of living things
  2. Burning wood – bush fires, home heating etc
  3. Burning fossil fuels
  4. Volcanic eruptions

How can carbon be stored –(carbon sinks)

  1. In forests
  2. In the ocean
  3. In organic matter – coal, oil,gas
  4. Rocks – as carbonates (eg calcium carbonates like in limestone caves)
  5. Animal shells.

Human impact

Humans have affected the cycling of matter through nature.

  1. Reduced fish stocks by 90%
  2. Altering water runoff by building dams or diverting rivers, hydroelectric projects,
  3. Agriculture – clearing of vegetation, reducing biodiversity, pollution by over use of fertilisers or pesticides, soil degradation, overstocking of farm animals .

Use the power point to add to your notes