BIOGEOCHEMICAL CYCLES

Bio: life Geo: Earth Chemical Cycle: repeats WHAT IS A BIOGEOCHEMICAL CYCLE?

The flow of chemical elements and compounds between living organisms and the physical environment. ▪Chemicals absorbed or ingested by organisms are passed through the food chain and returned to the soil, air, and water by such mechanisms as respiration, excretion, and decomposition. DEFINITION

Precipitation ▪Rain Transpiration ▪Plants “sweating” ▪Losing water to the air around them Evaporation ▪Water molecules warm up and get released in the atmosphere Infiltration ▪Water is deposited into the ground or into a body of water Runoff ▪Water leaves ground and is washed into a body of water THE WATER CYCLE

THE CARBON CYCLE

● An element ● The basis of life of earth ● Found in rocks, oceans, atmosphere What Is Carbon?

● The same carbon atoms are used repeatedly on earth. They cycle between the earth and the atmosphere. Carbon Cycle

● Plants pull carbon dioxide from the atmosphere and use it to make food – — photosynthesis. ● The carbon becomes part of the plant (stored food). Plants Use Carbon Dioxide

Photosynthesis v. Respiration

● When organisms eat plants, they take in the carbon and some of it becomes part of their own bodies. Animals Eat Plants

● When plants and animals die, most of their bodies are decomposed and carbon atoms are returned to the atmosphere. ● Some are not decomposed fully and end up in deposits underground (oil, coal, etc.). Plants and Animals Die

● Carbon in rocks and underground deposits is released very slowly into the atmosphere. ● This process takes many years. Carbon Slowly Returns to Atmosphere

Cycle – Repeats Over and Over and Over and Over …

Carbon Cycle Diagram Carbon in Atmosphere Plants use carbon to make food Animals eat plants and take in carbon Plants and animals die Decomposers break down dead things, releasing carbon to atmosphere and soil Bodies not decomposed — after many years, become part of oil or coal deposits Fossil fuels are burned; carbon is returned to atmosphere Carbon slowly released from these substances returns to atmosphere

● Additional carbon is stored in the ocean. ● Many animals pull carbon from water to use in shells, etc. ● Animals die and carbon substances are deposited at the bottom of the ocean. ● Oceans contain earth’s largest store of carbon. Carbon in Oceans

● Carbon sink: anything that absorbs (holds) more carbon that it releases ● Carbon source: anything that releases (gives off) more carbon than it absorbs ● Examples? Carbon Sinks

The Carbon Cycle

● Fossil fuels release carbon stores very slowly ● Burning anything releases more carbon into atmosphere — especially fossil fuels ● Increased carbon dioxide in atmosphere increases global warming ● Fewer plants mean less CO 2 removed from atmosphere Human Impact

● Burn less, especially fossil fuels SOLUTION Promote plant life, especially trees