Chapter 2 Cycles of Matter

Section 2.1 : Role of Water Water is available in finite amounts on Earth Water is a universal solvent Water is essential to humans and ecosystems Hydrological cycle plays a central role in biochemical cycles

Water is constantly being recycled Our bodies replaces what is lost through metabolic processes by what we eat and drink The water you drink today may have came from the Amazon River! 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

Within the hydrological cycle we see all phases of water: Solid, liquid, and gas Water has specific physical properties such as its high boiling point Water has a unique ability to trap heat and to transfer it as well 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 Water contains hydrogen and oxygen that are bonded covalently With its slight positive and negative ends, the molecule is POLAR Water’s structure allows it to dissolve a large number of substances

Cohesion and Adhesion of Water The bonding of water allows for attraction of water molecules to one another – COHESION This allows for things such as surface tension of water and how and insect can walk on water ADHESION of water to other molecules such as in plants allows for the transport of nutrients in the xylem of a tree or through our body’s internal systems

Section 2.2: Biochemical Cycles Carbon, oxygen, sulfur and nitrogen are found in living organisms, the land, atmosphere, and water. These are recycled through abiotic and biotic processes. Phosphorus is in living organisms, the land and water. They are also recycled through abiotic and biotic processes! When one biochemical cycle is effected – there are consequences to others.

Carbon and Oxygen Cycles Much carbon is released by our consumption of fuel burning and by the decomposition of organic molecules Producers, animals and decomposers will help in the rapid cycling of carbon. These help with the processes of photosynthesis and cellular respiration. Theses are by which connects the carbon and oxygen cycles together.

The two cycles are dependant on each other in order for them to occur. Photosynthesis requires CO2 to occur and Cellular Respiration requires O2 for it to occur! We’ll look further into these two processes in Unit 3!

The Greenhouse Effect Contains the gasses CO2, CH4 (methane), CFC’s 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 biosphere Consequences: Increased warming ( more towards the poles) Changes in weather patterns Ocean current may modify, a rise in the sea level Loss of natural habitats Inadequate amount of water for irrigation of crops worldwide Disease may expand from warm regions ot newer areas of warmth

Nitrogen Cycle Since so much of our atmosphere is composed of nitrogen (78%) we would expect that is accessible for our use. Yet most organism must have nitrogen fixed in order to use it. Bacteria can “fix” the atmospheric nitrogen by converting it into (NH4+) Plant 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. Ammonification is another process by which ammonium is converted into nitrite (NO2-) and then into nitrate (NO3-) Denitrification occurs where bacteria convert the nitrite or nitrate back to nitrogen gas

Nitrogen Cycle

Four Main Processes of Nitrogen in the Biosphere 1. Nitrogen fixation Biologically by bacteria in the roots of plants Industrially by fertilizer manufacturing 2. Ammonification 3. Nitrification ( nitrite NO2- and nitrateNO3- ions 4. Denitrification

Phosphorus Cycle This is an important nutrient but only found in limited supplies but is very important in growth and development of organisms. It is required for bones and teeth and our DNA It however does not cycle like other biochemical cycles. It is released by weathering of rocks and in the soil and air It can only be used if in (PO43-) which will dissolve in water Excess phosphates create algal blooms which create dead water zones which deplete oxygen for organisms to live! (Eurtrophication)