Biogeochemical Biogeochemical CyclesCycles

Presented by:Alok Kumar ChandrakarAlok Kumar Chandrakar

Objectives

Identify and describe the flow of nutrients in each biogeochemical cycle

Explain the impact that humans have on

the biogeochemical cycles

An ecosystem survives by a combination of energy flow and matter recycling.

Two Secrets of Survival: Energy Flow and Matter Recycle

Nutrient Cycles: Global Recycling

Global Cycles recycle nutrients through the earth’s air, land, water, and living organisms.

Nutrients are the elements and compounds that organisms need to live, grow, and reproduce.

Biogeochemical cycles move these substances through air, water, soil, rock and living organisms.

MATTER CYCLING IN ECOSYSTEMS

Biogeochemical cycles are cycling of chemical elements or nutrients from the abiotic environment to organism and then back to the abiotic environment.

The pathway by which chemical circulate through ecosystem involve both living (biotic) and nonliving (geological) components.

Involved organism (bio), environmental geology (geo) & chemical changes (chemical)

Biogeochemical Cycle

Most important are: The water cycle The carbon cycle The nitrogen cycle The phosphorus cycle The Sulfur cycle

The circulation of chemicals in these biogeochemical cycles and interactions between cycles are critical for the maintenance of terrestrial, freshwater and marine ecosystems. Global climate change, temperature, precipitation and ecosystem stability are all dependent upon biogeochemical cycles

Generalized Biogeochemical Cycle

There are strong forces of attraction between molecules of water

Water exists as a liquid over a wide temperature range

Liquid water changes temperature slowly

It takes a large amount of energy for water to evaporate

Liquid water can dissolve a variety of compounds

Water expands when it freezes.

Water’ Unique Properties

Water cycle

We alter the water cycle by:

Withdrawing large amounts of freshwater.

Clearing vegetation and eroding soils.

Polluting surface and underground water.

Contributing to climate change.

Effects of Human Activities on Water Cycle

Carbon dioxide - Oxygen Cycle CO2 is needed by plants in photosynthesis

(making food) and is a greenhouse gas. O2 is needed by organisms in respiration

(getting energy from food). Processes:

1. Photosynthesis2. Respiration3. Combustion

Carbon dioxide-Oxygen Cycle

1. Photosynthesis the process by which plants make food

(glucose) CO2 + H2O sunlight C6H12O6 + O2

releases O2 into the air

Carbon dioxide-Oxygen Cycle

2. Respiration the process by which living things get energy

by “burning” food C6H12O6 + O2 CO2 + H2O + energy releases CO2 into the air

Carbon dioxide-Oxygen Cycle

3. Combustion the process by which fuels are burned to

release energy (heat) fuel + O2 CO2 + heat releases CO2 into the air

Carbon dioxide - Oxygen CycleHuman Activities

1. Deforestation Increased CO2 global warming Decreased O2

2. Burning fossil fuels Increased CO2 global warming Air pollution

Mining Fossil Fuels Clearing Vegetation:

www.pewclimate.org/ images/figure4.gif

Nitrogen Cycle Nitrogen is needed by all organisms for cell-

building. Atmospheric nitrogen (N2) is inert and needs

to be changed into more reactive forms. Reactive forms of nitrogen: ammonium

(NH4+), nitrates (NO3

-)

Nitrogen Cycle Processes:

1. Nitrogen fixation2. Nitrogen uptake or assimilation3. Decomposition4. Nitrification5. Denitrification

Nitrogen CycleHuman Activities

1. Using synthetic nitrogen fertilizers Increased agricultural production Contamination of groundwater Algal blooms Fish kills

2. Burning fossil fuels Air pollution Acid rain Global warming

Phosphorous cycle

Effects of Human Activities on the Phosphorous Cycle

We remove large amounts of phosphate from the earth to make fertilizer.

We reduce phosphorous in tropical soils by clearing forests.

We add excess phosphates to aquatic systems from runoff of animal wastes and fertilizers.

Sulphur cycle

Effects of Human Activities on the Sulfur Cycle

We add sulfur dioxide to the atmosphere by: Burning coal and oil Refining sulfur containing petroleum. Convert sulfur-containing metallic ores into free

metals such as copper, lead, and zinc releasing sulfur dioxide into the environment.

The End