Cycles of Nature Matter, as well as energy, moves through an ecosystem and is constantly recycled. Nitrogen, water, oxygen and carbon are cycled globally because they are found in their gaseous form most of the time. Phosphorus is cycled locally because it remains almost entirely in the soil.

Biogeochemical Cycles The movement of particular chemicals through the biological and geological, or living and non-living, parts of an ecosystem May involve a change in state as they move through their cycles

Oxygen Cycle Oxygen is released from plants as a waste produce of photosynthesis. Humans and other organisms, including plants, take in this oxygen and release it as carbon dioxide through cellular respiration. Oxygen is also indirectly transferred through an ecosystem by the cycling of other nutrients, including carbon, nitrogen, and phosphorus.

Oxygen Cycle

Water Cycle Water from lakes, rivers, oceans undergoes EVAPORATION. Water vapor CONDENSES on dust in the air to form clouds. Water forms small drops that get bigger and heavier and PRECIPITATION occurs. INFILTRATION occurs. Runoff occurs as some water enters the streams, rivers and eventually the ocean. Plants pull water from the ground and then lose water through their TRANSPIRATION. Animals also put water vapor and water back into the cycle by exhaling and urinating. Only about 1% of the Earth’s water is available to us. The rest is either frozen or salty.

The Water Cycle

Carbon Cycle Carbon is the element of life and forms the basis for carbohydrates, proteins and fats. Autotrophs (producers) use carbon dioxide from the atmosphere during photosynthesis to form glucose. Heterotrophs (consumers) consume producers and take in these carbon containing molecules. Both heterotrophs and autotrophs carry out cellular respiration to release CO2 into the atmosphere. When organisms die and decay, they return carbon to the soil. Microorganisms break down these molecules to release carbon dioxide into the atmosphere.

The Carbon Cycle

Nitrogen Cycle Lightning and some nitrogen-fixing bacteria convert atmospheric nitrogen into nitrates. (Plants can’t use nitrogen in the atmosphere) Nitrates enter the ground and plants take them up and use them to produce proteins. Herbivores eat plants and convert plant proteins into animal proteins. Urine is formed and contains excess nitrogen in the form of ammonia which is released to the water or soil Organisms die and release nitrogen containing molecules to the soil. Plants reuse the nitrogen containing molecules and bacteria break them down and release nitrogen back to the atmosphere.

The Nitrogen Cycle

Phosphorus Cycle Phosphorus is needed for ATP, DNA, teeth and bones. Cycles in two ways, moving between the living and non-living parts of the environment. Phosphates are the most common form of phosphorus found in the environment. Short-Term Cycling a. Plants get phosphorus from the soil b. Animals get phosphorus from plants. c. Animals die/decompose and return phosphorus to the soil. Long- Term Cycling a. Phosphates washed into the sea from runoff are incorporated into rock formation as insoluble compounds. b. Rocks containing phosphorus are exposed as they erode and weather and phosphorus again becomes part of the system.

The Phosphorus Cycle

Human Impact on Nature’s Cycles Burning of fossil fuels and wood is raising the levels of carbon dioxide and contributing to global warming. Large amounts of inorganic nitrogen compounds are washed into rivers and streams from farming, sewage treatment and golf courses, causing heavy growth of algae and eutrophication. Phosphates from runoff pollute the lakes and streams causing heavy growth of algae. Destruction of forests causes a decrease in transpiration, altering weather patterns on Earth.

What are we doing to ensure that these Cycles continue? We need to understand the delicate interactions (relationships) between organisms and their environments to address the environmental problems we have created. CONSERVATION!