sign in sign up
<<
Home , Sulfur cycle

Chapter 2 Cycles of Matter

Section 2.1 : Role of Water z Water is available in finite amounts on Earth z Water is a universal solvent z Water is essential to humans and z Hydrological cycle plays a central role in biochemical cycles z Water is constantly being recycled z Our bodies replaces what is lost through metabolic processes by what we eat and drink z The water you drink today may have came from the Amazon River! z When the water fell as rain it went into the soil, which travelled to the ocean, which was evaporated into the clouds, which travelled a great distance, which fell as rain and was transported to the town water system that went to the tap in your home!! Hydrological Cycle z Within the hydrological cycle we see all phases of water: z Solid, liquid, and gas z Water has specific physical properties such as its high boiling point z Water has a unique ability to trap heat and to transfer it as well z If you think of the water currents in the ocean we see it moving from hotter to cooler areas ( think of a hot cup of coffee –the heat transfers to the cooler air around it so the air will warm up –it then rises till it cools!) The Universal Solvent z Water contains hydrogen and oxygen that are bonded covalently z With its slight positive and negative ends, the molecule is POLAR z Water’s structure allows it to dissolve a large number of substances Hydrogen Bonding z With its weak bonds, water molecules will break and re‐form z This usually occurs during phase changes z Density of frozen water is less than liquid water z As water freezes, it expands an the water molecules form a crystalline structure z These structures reflects how nutrients will cycle when dissolved in water Cohesion and Adhesion of Water z The bonding of water allows for attraction of water molecules to one another –COHESION z This allows for things such as surface tension of water and how and insect can walk on water z ADHESION of water to other molecules such as in allows for the transport of nutrients in the xylem of a tree or through our body’s internal systems Assignments: z Thought Lab 2.1 Page 38 z Q’s page 40 2, 4, 5, 6, 7, 9 Water and the Ecosystems z When water is in excess or scarce –organism will use their to help them. z If there is a drought –plants will close there stomata in order to conserve their water loss. Other organisms will be less active in times of drought to conserve there water loss. z Ecosystems are affected if the hydrological cycle is effected. z In turn all cycles of matter then would be linked to the hydrological cycle. Section 2.2: Biochemical Cycles z Carbon, oxygen, and nitrogen are found in living organisms, the land, , and water. These are recycled through abiotic and biotic processes. z Phosphorus is in living organisms, the land and water. They are also recycled through abiotic and biotic processes! z When one biochemical cycle is effected –there are consequences to others. Storage z As matter is cycled through the abiotic and biotic processes it allows organisms to obtain the nutrients essential for their survival. z At each step nutrients are stored temporarily in nutrient z When this occurs quickly it is called RAPID CYCLING and when it occurs slowly it is called SLOW CYCLING z It can occur as fast as a consumer decomposing to millions of years for it to occur! Nutrient Reservoirs Carbon and Oxygen Cycles z Much carbon is released by our consumption of fuel burning and by the decomposition of organic molecules z Producers, and decomposers will help in the rapid cycling of carbon. z These help with the processes of and cellular respiration. Theses are by which connects the carbon and oxygen cycles together. z The two cycles are dependant on each other in order for them to occur. z Photosynthesis requires CO2 to occur and Cellular Respiration requires O2 for it to occur! z We’ll look further into these two processes in Unit 3! Slow Cycling of Carbon z As we know millions of years ago, massive amounts of organic material was left to decompose and was compressed. Today we see this as the fossil fuels we use in our everyday . z Trees act as reservoirs that absorb much more than they emit to the atmosphere. z This is released when the forest is burned or stopped when the tree is cut down. If we look around the world we see huge deforestation activity that is increasing the

amount of CO2 that is being released into the air. z Photosynthetic organisms such as in our oceans is part of the largest sink of carbon in the world.

Rapid and Slow Cycling of Carbon The Greenhouse Effect

z Contains the gasses CO2, CH4, nitrous oxide(N2O) CFC’s z This is a NATURAL process that has been helping the Earth stay warm for BILLIONS of years, it is the ENHANCEMENT of it by excessive CO2 in the atmosphere that is changing the z Consequences: z Increased warming ( more towards the poles) z Changes in weather patterns z Ocean current may modify, a rise in the sea level z Loss of natural habitats z Inadequate amount of water for irrigation of crops worldwide z Disease may expand from warm regions ot newer areas of warmth Sulfur Cycle z Important nutrient as it makes up and vitamins that are needed for cells and tissues

2‐ z Most common form is (SO4 ) which is dissolvable in water z When organisms die, this nutrient is quickly returned to the air and to the ground z It has a distinctive smell like rotten eggs in the form of H2S (hydrogen )! Which means that decomposers are working to breakdown decaying matter. Acid Deposition z Combustions of fossil fuels creates sulfur dioxide –when combined with oxygen and fossil fuels in the atmosphere it creates sulfurous acid (H2SO3) and (H2SO4) z As these condense in the atmosphere they will fall in combination with the water as acid precipitation z From here they will return to the ground, air, water. z This is a natural occurring situation –BUT when excess from human burning of fossil fuels and production of fuels it increases the emission to our world – setting off an imbalance in the cycle!

Nitrogen Cycle z Since so much of our atmosphere is composed of nitrogen (78%) we would expect that is accessible for our use. z Yet most organism must have nitrogen fixed in order to use it.

+ z can “fix” the atmospheric nitrogen by converting it into (NH4 ) z such as legumes contain the bacteria so in the roots can convert the nitrogen into a useful form and the plant makes food for the bacteria. z Ammonification is another process by which ammonium is converted into nitrite ‐ ‐ (NO2 ) and then into nitrate (NO3 ) z Denitrification occurs where bacteria convert the nitrite or nitrate back to nitrogen gas Four Main Processes of Nitrogen in the Biosphere

1. z Biologically by bacteria in the roots of plants z Industrially by fertilizer manufacturing

2. Ammonification

‐ ‐ 3. ( nitrite NO2 and nitrateNO3 ions

4. Denitrification z This is an important nutrient but only found in limited supplies but is very important in growth and development of organisms. z It is required for bones and teeth and our DNA z It however does not cycle like other biochemical cycles. z It is released by of rocks and in the soil and air

3‐ z It can only be used if in (PO4 ) which will dissolve in water z Excess phosphates create algal blooms which create dead water zones which deplete oxygen for organisms to live! (Eurtrophication)

Read: Article of the Eurtrophication of Lake Winnipeg (Macleans 2009

Section 2.3 : The Balance of the Matter and Energy Exchange z Biotic and Abiotic processes maintain the balance and exchange z Natural processes and human activities will affect how energy is transferred and how matter will cycle through the biosphere Productivity z Our biosphere is not a closed system as we do get energy from the sun and the output of radiant energy back out of the atmosphere z To determine the rate at which an ’s producers obtain and store over time is to look at its PRODUCTIVITY z This is measured in energy/area/year (J/m2/a) z We look at how much BIOMASS is created by the organisms z Look at the diagram!

Balance? z In order to survive, organisms must find the balance of external and internal conditions. z Without this organisms would not survive! z With the biogeochemical cycles when one goes out of equilibrium –they all will! z We have over time tried to replicate conditions with no avail. Biosphere I and II were informational but not sustainable in replication of the Earth. z In order to preserve the balance we need to carefully look at what we do in nature Questions: z Chapter 2 page 64‐65 z 2,3,5,8,10,11,13,22

z Unit Review Questions page 68‐71 z 2,3,6,7,10,12,14,16,21,24,25,29,33,35