Environmental Chapter 2

Biogeochemical Cycles

Most things in nature get recycled and are used over again

Three common cycles– Water cycle– Carbon cycle– Nitrogen cycle

The Water Cycle

Water moves through the biotic and abiotic factors in the environment

Ways water can move:

– Precipitation water moves from the atmosphere to the land in the

form of snow, rain, sleet and hail. During evaporation and transpiration (evaporation from

plants and through skin) water cools and condenses, precipitation forms

About 91% falls into oceans. The rest falls on land to replenish the fresh water supply

– Evaporation Water moves from the land to the atmosphere

– Ground Water – when precipitation seeps into the ground and becomes part of the water table

– Runoff Water that flows on top of the ground

The Carbon Cycle

All living things have carbon in them All carbon that is on earth has been here

since the earth was formed

Ways that carbon moves through the environment

Photosynthesis – carbon gets taken out of the air and used by producers to make food

Respiration- carbon gets put back into the air by animals when they exhale

Decomposition – breakdown of dead materials by bacteria and fungi

Combustion – carbon in fossil fuels is released while burning

The Nitrogen Cycle

78% of the earth’s atmosphere is nitrogen Organisms cannot use nitrogen directly from

atmosphere Nitrogen fixation- when bacteria in the soil change

atmospheric nitrogen gas into usable nitrogen Lightening can also fix nitrogen Denitrification-different bacteria change usable

nitrogen into atmospheric nitrogen gas