CHEMICALS CYCLE IN ECOSYSTEMS

BASIC PATTERN OF CHEMICAL CYCLING

Three general steps

Producers incorporate chemicals from the nonliving environment into organic compounds

Consumers feed on the producers, incorporating some of the chemicals into their own bodies and releasing some back to the environment in waste products

As organisms die, decomposers break them down, further supplying the soil, water and air with chemicals in inorganic form. The producers gain a renewed supply of raw materials for building organic matter and the cycles continue.

THE NITROGEN CYCLE

Nitrogen fixation

Process that converts the nitrogen gas to ammonia (NH3)

Nitrification

Process that converts ammonium to nitrates

AmmoniumNH4

NitratesNO3

Form of N that

producers can use

Nitrogen Fixation

Nitrification

THE WATER CYCLE

Transpiration

Evaporation from the plant’s leaves

Maple tree – could enter 200 liters back into the atmosphere!

HUMAN ACTIVITIES CAN ALTER ECOSYSTEMS

IMPACT ON CHEMICAL CYCLES

CARBON CYCLE IMPACTS

Deforestation

Clearing of forest for agriculture, lumber and other uses

Adds 20% of CO2 added to atmosphere

80% is from worldwide burning of fossil fuels

GREENHOUSE EFFECT

Process by which atmospheric gases trap heat close to Earth’s surface and prevent it from escaping into space

Global Warming

Overall rise in Earth’s average temperature

NITROGEN CYCLE IMPACTS

Eutrophication

Rapid growth of algae in bodies of water, due to high levels of nitrogen and often phosphate

Acid Rain

Precipitation that carries acid back to Earth’s surface

WATER CYCLE IMPACTS

Deforestation

Drawing water from river or aquifers for household use or crop irrigation

BIOLOGICAL MAGNIFICATION

Process by which pollutants become more concentrated in successive trophic levels of a food web

OZONE SHIELD

Ozone – O3

Ozone layer – 17-25 kilometers above Earth

CFC’s – chlorofluorocarbons – banned in the 1980’s