N2 in Atmosphere

NH3

NO3-

and NO2-

Section 3-3

NITROGEN CYCLE

BIOLOGY; Miller and Levine; Prentice Hall; 2006

https://www.youtube.com/watch?v=w03iO_Yu9Xw

WHY IS NITROGEN IMPORTANT?

Image by Riedell

__________________make DNA and RNA

Adenine (nitrogen base) is used in _______

Makes AMINO part of _________ (proteins)

Image by Riedell

http://web.jjay.cuny.edu/~acarpi/NSC/12-dna.htm

NITROGEN BASES

ATP

amino acids

79% of the atmosphere is made up of NITROGEN gas (N2)

Image by Riedell Image by Riedell

http://web.jjay.cuny.edu/~acarpi/NSC/12-dna.htm

BUT we _____ use the nitrogen gas we breathe!

The bond in N2 gas is sostrong it can only be broken by__________________________________________________

CAN’T

lightningVolcanic activityfew special bacteria

http://www.slic2.wsu.edu:82/hurlbert/micro101/images/101nodules21.gif

Bacteria that live ______________and in _________ relationships withplants called _________, take nitrogen from the atmosphere and turn it into ______________, a form that is usable by plants.

THIS PROCESSIS CALLED_________________

in the soilsymbiotic

legumes

AMMONIA (NH3)

NITROGEN FIXATION

Image from: http://www.utdallas.edu/images/departments/biology/misc/gonzalez-image.jpg

and http://www.cibike.org/CartoonEating.gif

modified by Riedell

Other bacteria in the soil convertammonia into ________________& _________________which plants can also use. The nitrogen we need for proteins, ATP, and nucleic acids comes from

the ___________ ___________ we breathe!

NITRATES (NO3- )

FOOD WE EATNOT THE AIR

& NITRITES (NO2-)

N2 in Atmosphere

NH3

NO3-

and NO2-

Section 3-3

NITROGEN CYCLE

BIOLOGY; Miller and Levine; Prentice Hall; 2006

Bacteria that live ______________also carry out the reverse process

___________ → _____________.

THIS PROCESSIS CALLED_________________

in the soil

NITRATES & NITRITES NITROGEN GAS

DENITRIFICATION

• Until the 20th century, N-fixation was only natural and most wild plants thrive in low N-levels

• Scientists developed a way to fix N…

• Farmers increased crop yields

• More N introduced into environment than ecosystem can absorb and use!!

Artificial Fertilizers!!

Agriculture and Nutrient cyclingKey Ideas:

• N & P both essential to living things• Rate of cycles depends on how fast

things break down (decompose)– temp, moist soil, O2… decomposition and cycle

rate…

• N & P leave the soil in plants and when harvested are removed from ecosystem… – would deplete soil if not replaced

• Fertilizers restore nutrients and production from land… can double yields!

• Too much fertilizer can change the pH of soil (acidic) & impact plants growth

Problems???1. Algal Blooms• Spring run-off carries fertilizer-rich

soil into lakes causing algae to “bloom”(grow rapidly) & then die

• Bacteria decompose algae (use O2), therefore, bacteria levels & O2levels

• O2 levels impact fish… die… … more decomposition… O2 levels

• Nitrates convert to Nitrites are harmful to infants and can accumulate in water!

Problems ???2. Eutrophication of lakes• Oligotrophic lakes are deep, cold, and

clear with low nutrient levels and limited producer populations

• Eutrophic lakes are shallow, warmerand nutrient-rich. Favoured by producers… murky water

• These lakes become more shallow and eventually fill in and dry out

• Lakes transform from oligotrophic to eutrophic over 100s to 1000s of years

• Adding nutrient-rich substances (human waste, fertilizers in runoff, etc) can accelerate the transformation or “eutrophication” of lakes

… concerning??

NO

NO3

SO2

pollutants

+ H2O

Water vapour in air

H2SO4

HNO3

acids

acid precipitation(rain, snow)

3. Acid Precipitation

• Acid Precipitation– 40x more acidic than normal rain

– Kills fish, soil bacteria, plants

– Alkaline soils are more resistant (buffer) acidic soils are more susceptible

**airborne can travel and turn to acid when contact H2O• ex. Dew on lawn, respiratory tract

Direct Effects – dissolve statues, corrode metal, damage buildings

– Respiratory problems, asthma, bronchitis

– Irritate eyes and skin

Ecosystem effects– Damage trees - susceptibility to disease