Recycling Materials and nutrients

• Energy leaves system but materials are recycled

Water Cycle

• Water evaporates from seas and land

• Condenses into clouds (warm over oceans, cool over land)

• Water precipitates over land

• Fills lakes, rivers, aquifers and Returns to ocean

Carbon Cycle

• Plants remove carbon dioxide from atmosphere; change to sugars• Sugars pass to herbivores, carnivores, scavengers, decomposers

that release carbon dioxide• Most carbon in oceans as bicarbonate and sediments, and

eventually sedimentary rocks and fossil fuels

Carbon Locations

Human Effects on Carbon Cycle• Burning fossil fuels releases carbon dioxide into

atmosphere• Carbon dioxide traps solar energy as heat — called the

greenhouse effect• Global temperatures increasing• Negative Effects: melt polar ice caps, raise sea levels,

change climates, change growing seasons

What humans can do to help to remove carbon dioxide from the atmosphere:

• Burn less fuel• Plant trees; carbon stored in wood

Nitrogen Information

• Nitrogen is the most abundant element in atmosphere, but not usable for most organisms

• For nitrogen to be available to organisms, it must be “fixed”: changed into ammonium ions (NH4+) or nitrate ions (NO2-)

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• One source of fixed nitrogen is Nitrifying bacteria, some free living, most in root nodules of some plants called legumes (peas and beans)

Nitrogen Cycle

Humans and the Nitrogen Cycle• Humans adding fixed nitrogen to ecosystems

– fertilizers– burning

fossil fuels

Effects of Increased Nitrogen on Ecosystems

• Soils become more fertile

• Decreases diversity

• Aquatic systems– Increases algae growth and plankton

– Dead algae and fecal pellets increase bacterial growth

– Bacteria consume oxygen

– Animals leave or die — dead zone