Carbon Cycle

Carbon Carbon exists in the nonliving environment as: Carbon dioxide (CO 2 ) Carbonic acid ( HCO 3 − ) Carbonate rocks (limestone and coral = CaCO 3 ) Deposits of Fossil fuels Dead organic matter

Organic Carbon Hydrocarbons: CH 4 Carbohydrate: CH 2 O lipids Other molecules

Inorganic carbon Carbon Dioxide: CO 2 Calcium Carbonate: CaCO 3 Mandale Limestone Quarry

Carbon Fixation The conversion process of inorganic carbon (carbon dioxide) to organic compounds by living organisms.

Autotrophs absorb CO 2 from atmosphere Convert to carbohydrates, lipids & other carbon compounds Reduces CO 2 in atmosphere Average concentration is 0.039%

???? Why is the concentration of CO 2 lower above parts of the earth’s surface where photosynthesis rates are high? Where are these locations?

????? Discuss with a neighbor how removing the rain forests would affect global CO 2 levels.

Carbon is removed from the atmosphere in several ways Photosynthesis. The oceans when the seawater becomes cooler, more CO 2 dissolve and become carbonic acid. (ocean pH reduced) Consequences???? In the upper ocean areas organisms convert reduced carbon to carbohydrates & other compounds.

Autotrophs absorb CO 2 from atmosphere Autotrophs utilize CO 2. Creates concentration gradient between cells atmosphere Diffuses high to low Stomata in plants

Photosynthesis CO 2 + H 2 O + sunlight  CH 2 O + O 2

CO 2 in solutions Dissolves in water forming carbonic acid CO 2 + H 2 O  carbonic acid  hydrogen + carbonate ions pH reduced Carbon  carbohydrates, other

Carbon is released into the atmosphere in several ways Respiration by plants and animals. Decay of animal and plant matter. Combustion of organic material Production of cement. The ocean releases CO 2 into the atmosphere. Volcanic eruptions and metamorphism

Respiration CO 2 – aerobic waste product Non-photosynthetic root cells Animal cells Saprotrophs Diffuses out of cells into atmosphere & water

Respiration CH 2 O + O 2  CO 2 + H 2 O + energy

Methanogenesis the formation of methane by microbes known as methanogens. Organisms capable of producing methane have been identified only from the domain Archaea

Methanogensisis Bacteria  organic matter  organic acids, alcohols, H 2, CO 2 Bacteria  organic acids + alcohols  acetate, H 2, CO 2 Archaeans produce CH 4 from acetate, H 2, & CO 2 Mud & swampy areas Guts of cattle, sheep Buried organic material

?????? As permafrost melts due to increasing global temperatures explain the impact on CO 2 levels. Be able to support your reasoning.

Oxidation of methane Methane released into atmosphere is oxidized and converted to carbon dioxide and water 12 years

Combustion Organic matter that burns in the presence of oxygen produces carbon dioxide and water Forest fires & other biomass Natural causes Burning of rain forests for farm land Burning of fossil fuels

Combustion or Oxidization of hydrocarbon CH O 2  CO H 2 O + energy CH 4 + O + OH˙  CO 2 + H 2 O

Limestone Animals containing calcium carbonate that become fossilized form limestone Mollusc shells Hard corals Deposits form in sea beds 10% of sedimentary rock 12% of the mass of calcium carbonate is carbon

Peat formation Incomplete decomposition Anaerobic conditions Water logged – saprotrophs cannot thrive Acidic conditions Peat: dark brown, acidic, incompletely decomposed organic matter 3% of Earth’s surface – up to 10 meters, bogs

Fossilized organic matter Coal- peat buried under sediments, compressed, heated Pennsylvanian sub-period of Carboniferous Sea level rose & fell Oil & natural gas- sea & lake mud Anaerobic conditions, incomplete decomposition Organic material buried, forms mixtures of liquid carbon compounds & gases (methane)

Fossil Fuels Petroleum Natural Gas Coal

Fossil Fuel 86% of global primary energy consumption is fossil fuels.

Human Impacts on the Carbon Cycle Burning fossil fuels have serious impact on the carbon cycle.

Carbon reservoirs The atmosphere. The biosphere (include fresh water systems and non-living organic material, such as soil carbon). The oceans ( including dissolved inorganic carbon and living and non-living marine biota). The lithosphere (sediments, Earth core including fossil fuels).

Carbon reservoirs

Carbon Cycle

Draw Carbon Cycle combustion

CO 2 Concentration Pre-Industrial value: 280 ppm (600 billion tons) Current value: 380 ppm (800 billion tons) Critical value: 560 ppm (1200 billion tons)

Keeling Curve