UNIT 1 SUSTAINING ECOSYSTEMS

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1 UNIT 1 SUSTAINING ECOSYSTEMS Chapter 2 Biogeochemical Cycles Science 10

2 Change & Recovery in Ecosystems (you do not need to copy) What happens to the materials that make up a truck when it begins to rust? What happens to the tree after it dies?

Sugar, carbohydrates, proteins, amino acids Inorganic substances Do not contain

3 Cycling of Matter in Ecosystems Organic substances Contain atoms of Carbon and Hydrogen Are broken down into simpler forms in living things Ex. Sugar, carbohydrates, proteins, amino acids Inorganic substances Do not contain combination of carbon and hydrogen Ex. Water (H 2 O), ammonia (NH 3 ), Carbon dioxide (CO 2 )

4 Elements Essential to Life Carbon Hydrogen Nitrogen Oxygen Phosphorus (Sulfur needed for protein production. Not DNA) Why do we NEEEED these elements? All elements needed for DNA!

5 Biological Processes Involved in Nutrient Cycling 1. Photosynthesis Using Sun s light energy, Plants convert CO 2 and H 2 O into O 2 and sugar 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 2. Respiration Animals use O 2 and sugar, converting it to CO 2 and H 2 O C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O

6 More Processes 3. Decomposition Remains of dead organisms are broken down by bacteria and fungi All molecules are released into soil 4. Excretion Waste material from animals is broken down and returned to the soil 5. Assimilation Conversion of molecules (by bacteria) into a useable form (for plants). Nitrification, denitrification

7 Cycling of Organic Matter (Don t need to copy) The atoms and molecules available to make up organisms on earth is limited All the atoms MUST be recycled in order for new organisms to form. It is very likely that at least one of the carbon atoms in your body was also in a 70 million year old dinosaur

8 Recycling of Matter by Micro-organisms (Don t need to copy)

9 The Matter Cycle (Don t need to copy) Decomposers Person Soil Cow Grass 1. Dead plants and animals are broken down by decomposers their atoms / molecules are released into the system to be re-used 2. Atoms, molecules accumulate in the soil 3. Nutrients are taken up by grasses 4. Cows eat the grass nutrients and atoms are passed on to the cow 5. Person eats cow nutrients and atoms are passed on to person 6. Each of these things can die, the atoms are broken down by decomposers and recycled for the next living things

10 The Oxygen Cycle Photosynthesis: 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 Respiration: C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O What do you notice about these two chemical reactions?

11 The Oxygen Cycle (Don t need to copy) Oxygen (in atmosphere) PHOTOSYNTHESIS by green plants Combustion (burning stuff) RESPIRATION by plants, animals and decomposers Carbon Dioxide (in atmosphere)

12 The Carbon Cycle (Don t need to copy) CO 2 in the atmosphere Photosynthesis - carbon is stored in the biomass volcanic eruption Glucose Decomposition Aerobic respiration Weathering CO 2 dissolved in water Ocean sediment combustion Conversion to fossil fuels Fossil fuels

reservoirs (storage areas) for carbon are the bodies of living things 2.

13 The Carbon Cycle Two groups of carbon sources in the carbon cycle 1. Biotic - Aerobic respiration (in the presence of O 2 ), and decomposition The organic reservoirs (storage areas) for carbon are the bodies of living things 2. Abiotic - Combustion and geological activity The inorganic reservoirs for carbon are the atmosphere, the oceans, and the Earth s crust

14 (Don t need to copy)

15 Monday s Lesson is Complete

16 The Nitrogen Cycle NITROGEN is a component of many organic molecules. forms an essential part of amino acids (the building blocks of proteins) and forms part of DNA. essential for all living cells. in gas form (N 2 ) makes up about 78% of atmosphere.

17 The Nitrogen Cycle Most organisms cannot use nitrogen in the gaseous form found in the air we breathe, so it must be in fixed forms that plants can absorb. So how do you fix N 2? There are 3 ways get ready for the ABC s of Nitrogen fixing

18 The Nitrogen Cycle ~ 4 Processes Process #1 ~ NITROGEN FIXATION (must fix N 2 so it can be absorbed by Plants and get into food chains). only a small amount is fixed this way ~ about 10% Atmospheric fixation - lightning breaks nitrogen bonds they combine with oxygen in the air forming nitrogen oxides these dissolve in rain, forming nitrates nitrates rain only earth plants absorb nitrates

19 Nitrogen Fixation (cont.) bacteria fix 60% of nitrogen gas Biological fixation Bacteria are the only organisms able to take N 2. They combine it with hydrogen to make ammonia (NH 3 ). Most are free-living in soil. Some have developed an association with certain plants. In return for sugars from the plant, these bacteria fix nitrogen which can be used by the plant for growth.

20 Nitrogen Fixation (cont.) Commercial (industrial) fixation Smarty pants people figured out a way to convert N 2 into ammonia (NH 3 ) too! Today, about 30% of the total fixed nitrogen is manufactured in ammonia chemical plants. See? The ABC s of fixing nitrogen! You re welcome ;-)

21 The Nitrogen Cycle ~ 4 Processes Process #2 ~ NITRIFICATION Specialized nitrogen-fixing bacteria convert ammonia into nitrites (NO 2 ) Another type of specialized bacteria transforms the nitrites into nitrates (NO 3 ) BAM! Plants can easily absorb nitrates and use them to form proteins (food chains!).

22 The Nitrogen Cycle ~ 4 Processes Process #3 ~ DECAY (another way ammonia is produced) decomposers break down the molecules in excretions and dead organisms into ammonia (NH 3 ) and ammonium (NH 4+ ) (remember that polyatomic?) most of the ammonia produced by decay is converted into nitrates by those special nitrifying bacteria.

23 The Nitrogen Cycle ~ 4 Processes Process #4 ~ DENITRIFICATION (Once again bacteria to the rescue!) The only process that puts nitrogen back into the atmosphere. Yet another specialized bacteria starved of oxygen strip away oxygen from any unused nitrates (NO 3 ) (Hey bacteria need to breathe too!) Once oxygen has been stripped away, the nitrogen bond with each other (N 2 ) and return to atmosphere again.

24 Nitrogen Cycle ~ review 1

25 Nitrogen Cycle ~ review 2

26 Nitrogen Cycle ~ review 3

27 Lesson Complete This one you ll need to study eh?

28 Phosphorus Cycle Phosphorus is somewhat abundant in organic matter, accounting for ~0.2% of biomass Its largest store is rocks and minerals, but it is rarely abundant within food chains. (That is why it s a component of artificial fertilizers). The key nutrient is phosphate (PO 4 3- ), which often limits plant productivity, especially in freshwater. It is the slowest of the matter cycles.

29 The Phosphorus Cycle

30 Eutrophication Caused by an oversupply of nutrients, which causes explosive growth of plants and algae. When these organisms die, they consume the oxygen in the body of water, decreasing oxygen levels (1% - 30% dissolved oxygen. Fish need 80%). Phosphorus is the main culprit but excessive nitrogen is problematic as well. (Both of which are found in artificial fertilizers). The source of these excess phosphates are detergents, industrial/domestic run-off, and fertilizers. dominant contributors to eutrophication industrial/domestic run-off and agriculture. Due to human activities, the amount of nitrogen has doubled in the last 50 years. The eutrophication of the Potomac River is evident from the bright green water, caused by a dense bloom of cyanobacteria.

Agricultural practices often use large amounts of nitrogen-containing fertilizers. Excess nitrogen is washed away, or leaches, into the waterways.

31 Agricultural practices often use large amounts of nitrogen-containing fertilizers. Excess nitrogen is washed away, or leaches, into the waterways. This promotes huge growth in aquatic algae called algae blooms. Algae blooms use up all CO 2 and O 2 and block sunlight killing many aquatic organisms. Algae blooms can also produce neurotoxins that poison animals.

33 Bioaccumulation & Bioamplification Bioaccumulation Increase in concentration of a pesticide from the environment in all organisms in a food chain. Bioamplification The higher up the food chain, and thus the higher the trophic level, the higher the concentration of toxins. Often insects consuming herbicides. Top carnivores end up with the greatest concentrations of toxins.

34 Bioaccumulation

35 Bioamplification

Cycles of Ma,er. Lesson Overview. Lesson Overview. 3.4 Cycles of Matter

Cycles of Ma,er. Lesson Overview. Lesson Overview. 3.4 Cycles of Matter Lesson Overview Cycles of Ma,er Lesson Overview 3.4 Cycles of Matter THINK ABOUT IT A handful of elements combine to form the building blocks of all known organisms. Organisms cannot manufacture these