AP BIO Lab 12
Dissolved Oxygen
OXYGEN AVAILABILITY
Depends on:
~Temperature: Ability to hold oxygen
decreases as water temp gets warmer
~ Photosynthetic Activity:
In bright light, plants produce more oxygen
~ Decomposition Activity: As organic material decays,
microbial processes consume oxygen
~ Mixing/turbulence: Wave action, water falls, and rapids
all aerate water and increase oxygen concentration
~ Salinity: As water becomes more salty, it holds less oxygen
Temperature
Warm water dissolves
~ MORE SOLIDS than cold
~ LESS GAS than cold
– Reason why pop loses it’s fizz as it gets warm
http://randolphmase.files.wordpress.com/2009/03/glass-of-soda1.jpg
PHOTOSYNTHESIS
6 CO2 + 6 H2O +Light energy → C6H12O6 + 6 O2
RESPIRATION
C6H12O6 + 6 O2 → 6CO2 + 6 H2O + energy
Waves, waterfalls, rapids all increase
oxygen concentration
http://www.filetransit.com/images/screen/9fdd62319548bc0715910a209786d26f_Sparkling_Waves_ScreenSaver.jpg
http://www.chinaodysseytours.com/huangshan/photos/waterfall_7.jpg
http://www.waterfall-wallpapers.com/Waterfall/Waterfall-97/
http://biology.clc.uc.edu/courses/bio303/ecotones.htm
Amount of light drops off sharply with
increasing depth
Modeled by wrapping sample bottles in
increasing layers of screen
PRIMARY PRODUCTIVITY =
rate at which photosynthesizers produce
organic compounds in ecosystem
Can be measured by:
~ amount of CO2 used
~ rate of sugar formation
~ rate of oxygen produced
GROSS PRODUCTIVITY =
Total production of all organic compounds
made by photosynthesis
NET PRODUCTIVITY =
Organic material that remains after cellular
respiration uses some of these
compounds for their energy needs
Net productivity = Gross productivity - respiraton
Determined by
measuring
oxygen production
in light
Determined by
measuring
oxygen consumption
in dark w/o
Photosynthesis
If measure these 2 . . .
We can calculate GROSS PRODUCTIVITY
PHOSPHATE TEST
NITRATE TEST
FIXATION OF VIALS
TITRATION
Don’t fill or empty syringe past the number markings
http://randolphmase.files.wordpress.com/2009/03/glass-of-soda1.jpg
Continue adding titrating
solution until blue color
changes to from purple
to pale yellow/colorless.
If color change does not
occur when the ring on the
plunger reaches the bottom
of the scale, refill the
titrator to the zero line and
continue titrating.
Keep track of volume used.
Maximum amount of oxygen can water hold
= SATURATION
What is the % saturation
of a sample with
8 mg/L oxygen at 15° ?
What is the % saturation
of a sample with
8 mg/L oxygen at 5° ?
http://www.moderngent.com/media/sponge_466x389.jpg
NITRATES
http://justgetthere.us/blog/archives/Threat-of-Nitrate-To-Our-Environment-and-Health..html
PHOSPHATES
http://www.scielo.br/img/revistas/sa/v63n2/28839f5.gif
WHY DO LAKES in SD TURN
GREEN IN SUMMER?
REMEMBER
YOUR OLD BIO !
When an ecosystem receives a LARGE input
of limiting nutrient (ie., fertilizer runoff) the
BLOOM
population increases dramatically = ALGAL
___________
http://sbt.blob.core.windows.net/storyboards/v1621335/eutrophication_thumb.png
Nitrates & phosphates from fertilizer/manure get
washed into the lake. Nutrients are no longer LIMITED.
Cause algae to grow fast and cover the surface
http://sbt.blob.core.windows.net/storyboards/v1621335/eutrophication_thumb.png
Algae block out sunlight needed for photosynthesis by producers
below. No photosynthesis → NO O2 → organisms below start to
die. Algae die too when they run out of food
http://sbt.blob.core.windows.net/storyboards/v1621335/eutrophication_thumb.png
Cellular respiration by decomposers as they
break down dead organisms uses up more O2
http://sbt.blob.core.windows.net/storyboards/v1621335/eutrophication_thumb.png
As O2 in water is depleted, animals and plants die
Gulf of Mexico Dead Zone
The DEADZONE forms each April, generally grows
throughout the summer, reaching a peak in late July.
http://www.ncat.org/nutrients/hypoxia/hypoxia.html
Gulf of Mexico Dead Zone
http://serc.carleton.edu/microbelife/topics/deadzone/index.html
At its peak, the nearly lifeless water can span
5,000 to 8,000-plus square miles, an area almost
the size of New Jersey
https://nofishleft.files.wordpress.com/2010/11/coastal-dead-zones.jpg
NITRATES
PHOSPHATES
http://backtoessentialsllc.com/our-services/alkaline-therapy/