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 condensation 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 Transpiration is when water moves from living things to the atmosphere. It is a form of evaporation

– 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