The Cycling of Matter

• To understand how matter cycles through ecosystems, you must understand the cycling of organic substances in living things.

• The materials stored in living things comes from a limited amount of matter.

• Therefore, all matter must be recycled. This recycling of matter involves the carbon, oxygen and nitrogen cycles as well as the role of decomposers.

• All matter tied up in the bodies of organisms must be decomposed and recycled.

• organic substance- compound that always contains carbon and hydrogen atoms, and often oxygen and nitrogen atoms. e.g. proteins, sugars, – e.g. C6H12O2, CH4

• inorganic substance - compounds that don’t contain a combination of hydrogen and carbon.– e.g. CO2 , H2O

Carbon Cycle

• carbon is the main atom of all living things. In inorganic form it mainly exists as carbon dioxide gas in the air. CO2 is also dissolved in sea water.

• plants use carbon during photosynthesis to make carbohydrates. This takes carbon from its inorganic state and transforms it into organic compounds. This carbon then gets passed up the food chain

• carbon is returned to its inorganic state when organisms digest food to get energy. Consumers use sugars in a cell reaction process called cellular respiration.

• Cellular respiration requires oxygen. This reaction releases energy to the body and gives off inorganic carbon dioxide to the air.

• Decomposer organisms also release carbon dioxide to the air

• some carbon has become buried as coal. This carbon is locked away out of circulation unless humans release it by burning fossil fuels (gas, oil, coal).

• These fossil fuel deposits, the ocean and boglands are huge reservoirs of carbon which are released slowly to the atmosphere.

Human Impact on the Carbon Cycle;

• the level of CO2 in the atmosphere is rising quickly way beyond normal levels. This is due to:

• 1. carbon released from natural reservoirs faster than normal due to burning of fossil fuels, burning forests.

• 2. less CO2 being removed due to removal of plants to clear land for agriculture, forestry or building.

• The result has been global warming

Global Warming

• global warming - a warming trend in our climate caused by excess greenhouse gases such as carbon dioxide.

• Greenhouse gas - any atmospheric gas that traps heat and adds to the greenhouse effect.– e.g. carbon dioxide.

• CO2 in the atmosphere provides a natural “greenhouse effect”. It traps reflected solar energy and warms the earth. However, since humans have increased the amount of CO2 in the atmosphere, we are causing too much heat to be trapped and it is changing our weather patterns and climate. The average global temperature is rising.

Global Warming• Enhanced Global warming is the term given to describe the

recent increase of the earth’s temperature as a whole. • The earth’s weather and climate is controlled by energy from

the sun, which warms the surface of the earth as it, in turn, deflects the energy back into space.

• Some of this deflected energy is retained within the atmosphere of the earth by greenhouse gases which prevent the energy from passing into space, thereby preserving heat.

• It is this process that results in the earth having a temperature which supports life.

• Global warming has occurred since the 1980's, and during this time, the seven warmest years in global meteorological history have been recorded.

Global Warming

• If the earth's warming trend continues into the next decade the earth may enter a period of climate change unlike any of the past.

• Changes in the concentration of heat-trapping gases "greenhouse gases" have played a major role, because these gases trap the heat and does not let it escape, therefore causing global warming or an increase in climate temperatures.

Global Warming

• The three primary greenhouse gases which are responsible for this warming include carbon dioxide, methane, and nitrous oxide, all of which naturally exist in the earth’s atmosphere.

• These three gases are required in order for the natural process of temperature control to occur.

• The problems arise when there is a surplus of these gases in the atmosphere.

Global Warming• Causes of excess greenhouse gases include: • Carbon dioxide is released into the atmosphere by the

combustion of solid waste, fossil fuels, wood and wood products.

• Methane emissions are a direct result of the production and transportation of coal, natural gas, and oil. The raising of livestock, and the decomposition of organic waste also contribute to the amount of methane emitted into the atmosphere.

• Nitrous oxide emissions are a result of agricultural and industrial activities as well as the burning of solid waste and fossil fuels.

http://www.windows.ucar.edu/tour/link=/earth/climate/images/greenhouse_gasses_jpg_image.html

Global Warming

• There are also greenhouse gases which do not occur naturally, that are generated by human activity. Examples of these gases include; chlorofluorocarbons found in refrigeration devices, hydrofluorocarbons, and perfluorocarbons.

• Each varies in their heat trapping ability and combined with those gases originally present in the atmosphere, serve to retain a sufficiently larger amount of heat then would naturally be retained.

Global Warming• Many people today may be unaware of the drastic

effects which global warming can have on our environment,

• These people are ignorant to the facts about this issue, and what these changes will mean to people all over the world.

• Because of the projected increase of the overall global temperature, climates around the world will likely to be affected.

• This could cause major disruptions to the environment.

Global Warming• A major issue which is causing concern is that of our own

health.• Throughout the world, the occurrence of particular diseases

and other threats to human health depend largely on the local climate. For example:

• extreme temperatures can directly cause the loss of life (although it has the greatest toll on very old and very young people),

• many severe diseases are only found in warm areas, • and as well warmer temperatures have been shown to

increase air and water pollution.

Global Warming

• Increasing temperatures may also increase the risk of infectious diseases, which only occur in warm areas, such as malaria, dengue fever, yellow fever, and encephalitis.

• These diseases which are spread by mosquitoes and other insects could become more common if warmer temperatures allowed these insects to inhabit places farther north.

Your Turn

• Do questions p. 65, # 1, 2, 4, 6, 7 (a) (b) (c)

The Nitrogen Cycle• Nitrogen is needed by all organisms to make proteins (tissue)

and DNA. 79 % of the air is nitrogen gas but plants and animals cannot get their own nitrogen from the air.

• Only plants can use inorganic forms of nitrogen such as nitrates, NO3 , found in the soil or dissolved in water, and extract - the nitrogen in them to use in making their own plant proteins.

• All consumers must consume other organisms to get their proteins.

• When organisms die, the nitrogen present in the proteins of living things gets recycled back into inorganic forms such as ammonia, nitrites and nitrates by the processes of decomposition and denitrification.

• Nitrogen - fixation stage• nitrogen fixation - the process of converting free atmospheric nitrogen

into nitrates.• Nitrogen gas in the atmosphere gets converted into nitrates, NO3 .

These are absorbed by the - roots of plants. This can occur in two ways:• (1) lightning in the atmosphere - causes nitrogen in the air to react with

oxygen to form nitrates.• (2) Nitrogen - fixing bacteria - give off nitrates as a waste product. Some

nitrogen fixing bacteria are free - living but many live in the roots of certain plants called legumes. They supply the legume plants with a steady supply of nitrogen in return for shelter in the roots and food. Legumes include beans, alfalfa and clover - type plants

Man’s Impact on the Nitrogen Cycle;

• We are adding extra nitrogen to many environments in the form of fertilizers and pollution wastes from many industries.

• Human sewage is often released into rivers with little treatment(e.g. Montreal into the St. Lawrence River) and act as fertilizer.

• Normally, there is a balanced amount of nitrate in an aquatic ecosystem. However, in areas near agricultural lands where lots of fertilizers are used, runoff into rivers have caused the levels of nitrate in lakes to get too high.

• this causes a process called eutrophication - pollution making a lake richer in nutrients.

• If the level of nitrate gets too high, an algal bloom can occur. This is where the algae population grows out of control, scumming over much of the lake’s surface.

• The algae, too many in number, block much of the light from reaching other plants growing underwater.

• Also, when the algae die, the decomposer bacteria in the water have lots of food. This causes their population to increase.

• All this extra decomposition uses up much of the dissolved oxygen in the water. This is very unhealthy to the ecosystem.

• It has a bad effect on many species, causing their numbers to decline. Fish and other aquatic animals may begin to die.

http://www.h2ou.com/h2images/NitrogenCycle-lgr-F.jpg

Decomposition stage

• Decomposer bacteria decay dead organisms. They break down the proteins in the dead organisms to produce ammonium.

• Other bacteria in the soil convert ammonium into nitrites. Another type of bacteria convert the nitrites into nitrates, becoming available again for plant use.

Denitrification stage

• Some of the nitrates in the soil is converted back into free nitrogen gas by certain bacteria called denitrifying bacteria. This returns nitrogen to the atmosphere.

Your Turn

• Do -questions, p. 69, # 1 - 4 and p. 71, # 3,4

Question 1

• Explain why nitrogen is important to organisms.

• Organisms require nitrogen to produce proteins and nucleic acids.

Question 2

• Nitrogen must be converted to nitrates before it can be used by organisms

• If the soil lacks nitrogen – fixing bacteria this it has few nitrates for the plants to take in

Question 4

• The bacteria convert nitrogen to nitrates from the plants and the plants provide sugar from photosynthesis for bacteria

Question 6

• Aerating lawn exposes denitrifying bacteria to oxygen and so reduces the breakdown of nitrates to nitrogen.

• The soil is able to retain the nitrates that would otherwise be lost

Question 10

• Clover grows in the older lawns because of the abundance of denitrifying bacteria. The bacteria in clover roots would benefit the lawn by providing more nitrates.

Question 3

• Algae blooms occur in spring as a result of spring runoff containing nitrates and nitrites

• Algae blooms promote an increase in herbivorous plankton and other organisms that can eat plankton. When the algae die the resulting increase in decomposers can cause oxygen depletion that can kill fish

Question 4

• High nitrate levels in drinking water can pose a problem for infants because their stomachs are not a s acidic as those of adults. Bacteria that convert nitrates to nitrites in the intestines and enter an infants less acidic stomach. The nitrates can inter the blood stream and bind to the hemoglobin.

The Oxygen Cycle

• Oxygen is cycled between the atmosphere and living (biotic) things. Oxygen is used in the process of cellular respiration by both plants and animals. Carbon is released in the form of CO2 as a waste product of this reaction.

• Plants take in the inorganic gas CO2 and use it in the process of photosynthesis to make organic sugars such as glucose, C6H12O6. Oxygen is released as a waste product of the photosynthesis reaction.

• The reactions of cellular respiration and photosynthesis are reciprocals of each other. The reactants of one reaction are the products of the other reaction.

Photosynthesis:

CO2 (g) + H2O (l) → C6H12O6 (s) + O2 (g)

Cellular Respiration:

C6H12O6 (s) + O2 (g) → CO2 (g) + H2O (g)

• C6H12O6 (s) + O2 (g) → CO2 (g) + H2O (g)Reaction Reactants Products

Photosynthesis Carbon dioxide + waterCO2 + H2O

glucose sugar + oxygenC6H12O6 + O2

Respiration glucose sugar + oxygenC6H12O6 + O2

Carbon dioxide + waterCO2 + H2O

Human Impact on the Oxygen Cycle

• Deforestation is the major impact by man. Trees are the earth’s largest oxygen – producing plants. Plants give off O2 to the atmosphere through photosynthesis. The destruction of forests lowers the amount of CO2 which is being converted into O2. The reduction in trees is a one of the contributing factors to global warming.

Ozone

• Ozone is a form of oxygen• In the atmosphere oxygen is found in three

forms O, O2, O3

• Ozone is formed when a solar ray hits a molecule of O2 causing it to split apart

• If one of these free atoms hits another O2 molecule then ozone is formed

Ozone

• In the stratosphere oxygen is constantly being bombarded by UV radiation, resulting in the formation of ozone

• Ozone serves as a protection layer, filtering out the harmful UV radiation

• In recent years human activity has led to the destruction of this layer and to the depletion of the ozone layer

Ozone

• Ozone's unique properties allow it to act as a protective layer around the earth

• It acts as a sunscreen, filtering out the damaging UV rays

• This layer is the thickest at the poles and thinnest at the equator

• Even though the radiation is strongest at the poles, stratospheric winds carry the ozone towards the poles

Ozone Depletion

• Chlorofluorocarbons (CFC’S) account for approximately 80% of the stratospheric ozone depletion

• Other compounds that cause ozone depletion are : halons, carbon tetrachloride, methyl chloroform, and methyl bromide

• These are called industrial halocarbons• These compounds are used in refrigerators,

furniture foam and fire extinguishers

Ozone Depletion

• Human activity such as deforestation, fertilizer use and fossil fuel combustion have also contributed to the loss of ozone

The Effects of Ozone Depletion

• Not yet fully understood• We know they are potentially severe• Ozone warms the stratosphere, but due to

decreasing ozone in the stratosphere, the stratosphere is cooling

• CO2 in the atmosphere is increasing, trapping heat in the troposphere, adding to the cooling effect of the stratosphere

Ozone Depletion and Humans

• Skin cancer• Eye damage and cataracts• Immunospuression

Ozone Story

Your Turn

Case Study : The Effects of Deforestation on Cycling

• p. 72 - 73 do items (b) - (g). • p. 73, # 1 - 3.

The Biomes of Canada (read pp. 88 - 92)

• Biome - a collection of ecosystems that are similar or related to each other, usually by the types of plants present in the area.

There are 4 biomes present in Canada:

• 1. Tundra• 2, Boreal Forest• 3. Temperate Deciduous Forest• 4. Grasslands

TundraAbiotic Factors Biotic Factors

Very low temperatures for most of year Rapid flowering plants

Short growing season Mosses and lichens

Permafrost below soil Caribou, ptarmigan, lemmings

Low precipitation

Poor soil quality

Active layer – the layer that thaws in summer to provide nutrients to plants

Slow decomposition due to cold temperatures

Boreal Forest BiomeAbiotic Factors Biotic Factors

Warmer than tundra Coniferous trees

Changeable weather Seed eating birds, squirrels, deer

Soil contains some water and is acidic Conifer trees dominate because well adapted to conditions ( waxy cuticle, small

surface area, slow shedding, pyramid shape and flexible branches))

Precipitation is 40 cm/year + Limited food source for animals living on forest floor thus not great biodiversity

Very acidic soil due to conifer needles

Make up 80% of forests in Canada

Temperate Deciduous BiomeAbiotic Factors Biotic Factors

Longer grow season than boreal forest Deciduous trees

Higher temperatures than tundra or boreal forest thus faster recycling of

materials

Many shrubs and ferns

Fertile soil Many insects

Precipitation 100cm/year + Deer, black bear, shrews, mice

Wide ecotone Shift in types of plants and animals as you move from north to southGreat biodiversity

Grassland Biome:Abiotic Factors Biotic Factors

Longer growing season than boreal forest Fescue grass

Temperature higher than tundra or boreal forest Grasshoppers, bison, snakes, hawks

Rich, fertile soil One layer thus low biodiversity

Precipitation from 25 to 75 cm/year

Abiotic factors much the same as deciduous forest except less precipitationFires act as decomposers