The Earth’s Natural Recycling Process Nature’s Cycles The Earth’s Natural Recycling Process

Nutrient Cycles Outline I. Water Cycle 1. evaporation 2. transpiration 3. precipitation Carbon 1. Plants 2. Animals III. Nitrogen 1. Air 2. Nitrogen-fixing bacteria

Matter cycles from the environment to organisms then back to the environment. ENERGY DOES NOT CYCLE!!!

WATER CYCLE 2 ways water enters the atmosphere: Evaporation: water moves into the atmosphere as it changes from liquid to gas Transpiration: evaporation of water from the leaves of plant through open stomata

Water Cycle Clouds form as vapors cool and condense Condensation – water changing from a gas to a liquid (e.g. clouds, water on a window) Precipitation – water returning to earth in the form of rain, snow, sleet, hail. Precipitation can return to oceans through runoff or groundwater

Glaciers

The Carbon Cycle

Carbon Cycle The original atmosphere was 95% carbon dioxide but now less than 1% Carbon entered the ecosystem as plants removed carbon dioxide from air during photosynthesis Consumers eat plants (and therefore carbon) and release it back into the atmosphere in the form of carbon dioxide during respiration

The Carbon Cycle: The Circle of Life Dirt becomes corn, which is eaten by cows. The cows are then eaten by humans. The humans are eaten by worms, which decompose what they eat. The decomposed nutrients (i.e. carbon) return to the soil. The cycle then repeats.

So where is the rest? Organisms: composed mainly of carbon Ocean: carbon dioxide dissolves easily in water Rocks: bodies of dead organisms that didn’t decompose; carbon dioxide released into the air when we burn fossil fuels

Oil in Alaska

The Nitrogen Cycle Why is nitrogen important? All organisms need nitrogen to make proteins (amino acids)! Air is 78% nitrogen (N2)!, However, there is a shortage! If 78% of the atmosphere is nitrogen, why is there a shortage? Plants can’t use nitrogen gas in that form

How do we solve the nitrogen shortage problem? Bacteria to the rescue! Bacteria can use it! Nitrogen fixing Bacteria: live on the roots of plants and “fix” nitrogen by turning it into a usable form (e.g. ammonia, nitrite, nitrate). Example: Legumes (peanuts, beans, clover)

Nitrogen Cycle Animals get nitrogen from eating plants When animals die, decomposers break them down and release nitrogen gas back into the atmosphere and return some to the soil so plants can reuse it. However, when there isn’t enough nitrogen available, fertilizer is necessary!!

Animals eat plants and each other The Nitrogen Cycle 3 2 Animals eat plants and each other Decomposers break down plants and animals 1 4 5

Bioaccumulation Biomagnification: increasing concentration of a a toxic chemical in organisms at higher levels in a food chain. (poisons become more concentrated at the top of the food web) Bioaccumulation: buildup of toxins in an organism Ex. Insecticide DDT