Biogeochemical Biogeochemical CyclesCycles

What is ecology?What is ecology? The scientific study of interactions The scientific study of interactions

among organisms and between among organisms and between organisms and their environment is organisms and their environment is ecology.ecology.

The biosphere contains the combined The biosphere contains the combined portions of the planet in which all of life portions of the planet in which all of life exists, including land, water, and exists, including land, water, and atmosphere.atmosphere.

Recycling in the BiosphereRecycling in the Biosphere Matter can be recycled through the Matter can be recycled through the

biosphere because biological systems do biosphere because biological systems do not use up matter, they transform it. not use up matter, they transform it. – The matter is assembled into living tissue or The matter is assembled into living tissue or

passed out of the body as waste products passed out of the body as waste products Biological systems pass the same Biological systems pass the same

molecules around again and again within molecules around again and again within the biosphere.the biosphere.– OO22 you breath may have been same O you breath may have been same O22 a a

dinosaur used millions of years agodinosaur used millions of years ago

The Water Cycle

All living things Require water!

Water CycleWater Cycle

During the water cycle, water During the water cycle, water molecules enter the atmosphere as molecules enter the atmosphere as water vapor, a gas. This occurs water vapor, a gas. This occurs through through evaporationevaporation, which is the , which is the changing of liquid water into water changing of liquid water into water vapor. vapor. – It can also evaporate from the leaves of It can also evaporate from the leaves of

plants during plants during transpirationtranspiration

Warm, moist air rises. Eventually it Warm, moist air rises. Eventually it cools and condenses into tiny droplets cools and condenses into tiny droplets that form clouds.that form clouds.

When water Droplets become large When water Droplets become large enough, the water returns to Earth as enough, the water returns to Earth as precipitationprecipitation– Rain, snow, sleet, hailRain, snow, sleet, hail

On land, water runs along the surface On land, water runs along the surface of the land until it reaches rivers, of the land until it reaches rivers, streams, lakes, etc… streams, lakes, etc…

Water also seeps into the soil, Water also seeps into the soil, where it enters plants through the where it enters plants through the roots.roots.

AND THE WATER CYCLE BEGINS ALL AND THE WATER CYCLE BEGINS ALL OVER AGAIN!OVER AGAIN!

The food you eat provides energy The food you eat provides energy and chemicals that keep you alive. and chemicals that keep you alive. All the chemical substances that an All the chemical substances that an organism needs to sustain life are organism needs to sustain life are its its nutrientsnutrients..

The Carbon CycleThe Carbon CycleCO2 in

Atmosphere

CO2 in Ocean

Carbon CycleCarbon Cycle Carbon is a key ingredient in living tissues. It Carbon is a key ingredient in living tissues. It

forms animal skeletons, is an important forms animal skeletons, is an important component of the atmosphere, and is taken component of the atmosphere, and is taken up by plants in photosynthesis.up by plants in photosynthesis.

In the atmosphere, carbon is present as In the atmosphere, carbon is present as carbon dioxide (COcarbon dioxide (CO22). Carbon dioxide is ). Carbon dioxide is

released into the air by volcanic activity, released into the air by volcanic activity, burning of fossil fuels, and by decomposition burning of fossil fuels, and by decomposition of organic matter of organic matter (matter from living organisms)(matter from living organisms)

Animals COAnimals CO22 as a waste product of cellular as a waste product of cellular

respiration.respiration.

Carbon CycleCarbon Cycle Plants use carbon dioxide in photosynthesis Plants use carbon dioxide in photosynthesis

to build carbohydrates.to build carbohydrates. Carbohydrates are passed along food webs Carbohydrates are passed along food webs

to consumers. to consumers. (the animals that eat the plants)(the animals that eat the plants)

Breakdown of wastes and dead organisms Breakdown of wastes and dead organisms return carbon dioxide to the atmosphere.return carbon dioxide to the atmosphere.

In the oceans carbon is found in the form of In the oceans carbon is found in the form of calcium carbonate which breaks down and calcium carbonate which breaks down and returns carbon dioxide to the atmosphere.returns carbon dioxide to the atmosphere.

Nitrogen CycleNitrogen Cycle

N2 in Atmosphere

NH3

NO3-

and NO2-

Nitrogen CycleNitrogen Cycle All organisms require nitrogen to make All organisms require nitrogen to make

amino acids, which in turn are used to make amino acids, which in turn are used to make proteins. proteins.

Nitrogen makes up 78% of the Earth’s Nitrogen makes up 78% of the Earth’s atmosphere, but guess what? Even though atmosphere, but guess what? Even though nitrogen is in every breath of air we take, our nitrogen is in every breath of air we take, our bodies can’t use this nitrogen….So how is bodies can’t use this nitrogen….So how is nitrogen transformed into a form our bodies nitrogen transformed into a form our bodies can use?can use?

Friendly, bacteria, known as nitrogen-fixing Friendly, bacteria, known as nitrogen-fixing bacteria live in the soil and on roots of plants bacteria live in the soil and on roots of plants called legumes.called legumes.

These bacteria convert nitrogen gasThese bacteria convert nitrogen gas(N(N22)) into into ammonia ammonia (NH(NH33)) in a process called in a process called nitrogen nitrogen fixationfixation..

Other bacteria convert ammonia into nitrates Other bacteria convert ammonia into nitrates and Nitrites and Nitrites (NO(NO33

-- & NO & NO22-- ) ) which consumers which consumers

take in when they eat plants!take in when they eat plants!

Nitrogen CycleNitrogen Cycle

Nitrogen CycleNitrogen Cycle

When organisms die, decomposers return When organisms die, decomposers return nitrogen to the soil as ammonia. Some soil nitrogen to the soil as ammonia. Some soil bacterial convert nitrates into nitrogen gas bacterial convert nitrates into nitrogen gas by a process called by a process called denitrificationdenitrification..

Phosphorus CyclePhosphorus Cycle Phosphorus is essential to living Phosphorus is essential to living

organisms because it forms part of organisms because it forms part of important life-sustaining molecules important life-sustaining molecules such as DNA and RNA.such as DNA and RNA.

Phosphorus does not enter the Phosphorus does not enter the atmosphere. It remains mostly on land atmosphere. It remains mostly on land in rock and soil minerals and in ocean in rock and soil minerals and in ocean sediments.sediments.

It exists as inorganic phosphate.It exists as inorganic phosphate.

Phosphorus CyclePhosphorus Cycle As rocks and sediments wear down As rocks and sediments wear down

and are washed into rivers and and are washed into rivers and streams, the phosphate dissolves. streams, the phosphate dissolves. Plants absorb it.Plants absorb it.

It is then bound into organic It is then bound into organic compounds which cycle through the compounds which cycle through the food web, from producers to food web, from producers to consumers, and to the rest of the consumers, and to the rest of the ecosystem.ecosystem.

Nutrient LimitationNutrient Limitation If a nutrient is in short supply, it will limit an If a nutrient is in short supply, it will limit an

organism’s growth.organism’s growth. Farmers add nutrients to the soil in the form Farmers add nutrients to the soil in the form

of fertilizers, which contain nitrogen, of fertilizers, which contain nitrogen, phosphorus, and potassium.phosphorus, and potassium.

Open oceans are usually considered Open oceans are usually considered nutrient-poor environments.nutrient-poor environments.

Nitrogen is considered a limiting nutrient Nitrogen is considered a limiting nutrient because it cycles very slowly an is scarce in because it cycles very slowly an is scarce in the ocean.the ocean.

Nutrient LimitationNutrient Limitation Phosphorus is a limiting nutrient in Phosphorus is a limiting nutrient in

freshwater environments.freshwater environments. When aquatic environments receive a large When aquatic environments receive a large

supply of limiting nutrient, such as from supply of limiting nutrient, such as from fertilizer run-off, there can be a sudden fertilizer run-off, there can be a sudden increase in algae and other producers. This increase in algae and other producers. This results in an algal bloom.results in an algal bloom.– These blooms of algae can disrupt the These blooms of algae can disrupt the

equilibrium of an ecosystem.equilibrium of an ecosystem.