BIOCHEMICAL CYCLES

The movement of materials through the biotic (living) and abiotic (non-living) parts of an ecosystem BIOCHEMICAL CYCLES

Biogeochemical Cycles Biogeochemical Cycles are also known as Nutrient Cycles -They are the pathways that 4 materials vital to life follow through an ecosystem - - Carbon - Nitrogen - Phosphorus - Water These materials cycle through both biotic and abiotic reservoirs in an ecosystem -biotic reservoirs are the living things that these materials move through -abiotic reservoirs are the non-living things that these materials move through

Carbon is the backbone for many of the most important molecules used by living things. carbohydrates, fats, protein, nucleic acid Carbon exists as CO 2 in the atmosphere - CO 2 in the atmosphere can’t be used by living things – it must be converted into a usable form - How does CO 2 get converted? – Photosynthesis in plants - CO 2 is used to make glucose – the carbon in glucose can be used by living things

CO 2 in atmosphere Photosynthesis Cellular Respiration Combustion Coal Oil Death & Decomposition Fossil Fuels CO 2 is absorbed in water Limestone

Carbon Cycle Carbon returns to the atmosphere - cellular respiration - combustion All living things are biotic reservoirs The atmosphere and water are abiotic reservoirs Carbon Sink – A sink is a part of the cycle which removes a nutrient from the cycle for long periods of time - Limestone - Fossil Fuels

Carbon Cycle The carbon in fossil fuels has been stored in the earth for millions of years- Burning them for energy releases the CO 2 back to the atmosphere - causing a rapid increase in CO 2 in the atmosphere - CO 2 is a greenhouse gas which traps heat, warming the Earth - Increasing CO 2 is leading to Global Climate Change

Nitrogen is used by living things to make proteins and nucleic acids (DNA, RNA & ATP) Nitrogen exists in the atmosphere as N 2. 78% of the atmosphere is N 2 -the N 2 molecule consists of two nitrogen atoms so tightly bonded that they will not react with other elements and so can’t be used by living things. - N 2 can be split, but requires large amounts of energy– lightning can split N 2 -Once split by lightning, the nitrogen atoms bond with other elements and become useable by living things This accounts for 5 – 6 % of all nitrogen available to living things

Nitrogen Cycle: Nitrogen Fixation - Certain bacteria contain the enzymes necessary to convert N 2 into the nitrogen compound ammonia – NH 3 - these nitrogen fixing bacteria are found in the soil and in symbiotic relationships with certain plants primarily legumes, beans, peas etc…. -The ammonia can enter the food chain when plants assimilate it – take it up and use it or be converted by bacteria into nitrate NO 3 and then assimilated

Nitrogen Cycle: Man-made Nitrogen The Haber Process –Developed by Fritz Haber in 1909, this process joins N 2 and H 2 together to make ammonia ( NH 3 ) - The elements are driven together under high temperature and high pressure - In the last 60 years the use of ammonia as fertilizer has become wide-spread. - It has allowed humans to produce large quantities of food. However, excess nitrogen leeches into ground water or runs off into lakes and the ocean causing great harm