AP BIO Lab 12Dissolved Oxygen

OXYGEN AVAILABILITYDepends 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

http://randolphmase.files.wordpress.com/2009/03/glass-of-soda1.jpg

– Reason why pop loses it’s fizz as it gets warm

PHOTOSYNTHESIS6 CO2 + 6 H2O +Light energy C6H12O6 +

6 O2

RESPIRATIONC6H12O6 + 6 O2 6CO2 + 6 H2O + energy

→

→

Waves, waterfalls, rapids all increase oxygen concentration

http://www.waterfall-wallpapers.com/Waterfall/Waterfall-97/

http://www.chinaodysseytours.com/huangshan/photos/waterfall_7.jpg

http://www.filetransit.com/images/screen/9fdd62319548bc0715910a209786d26f_Sparkling_Waves_ScreenSaver.jpg

Amount of light drops off sharply with increasing depth

Modeled by wrapping sample bottles inincreasing layers of screen

http://biology.clc.uc.edu/courses/bio303/ecotones.htm

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 thesecompounds for their energy needs

Net productivity = Gross productivity - respiraton

Determined bymeasuring oxygen productionin light

Determined by measuringoxygen consumption in dark w/o Photosynthesis

If measure these 2 . . . We can calculate GROSS PRODUCTIVITY

PHOSPHATE TEST

NITRATE TEST

FIXATION OF VIALS

http://randolphmase.files.wordpress.com/2009/03/glass-of-soda1.jpg

TITRATION

Don’t fill or empty syringe past the number markings

Continue adding titratingsolution until blue color changes to from purpleto pale yellow/colorless.

If color change does notoccur when the ring on theplunger reaches the bottomof the scale, refill thetitrator to the zero line andcontinue titrating.

Keep track of volume used.

Maximum amount of oxygen can water hold

= SATURATION

http://www.moderngent.com/media/sponge_466x389.jpg

What is the % saturation of a sample with 8 mg/L oxygen at 15° ?

What is the % saturation of a sample with8 mg/L oxygen at 5° ?

NITRATES

http://justgetthere.us/blog/archives/Threat-of-Nitrate-To-Our-Environment-and-Health..html

http://www.scielo.br/img/revistas/sa/v63n2/28839f5.gif

PHOSPHATES

WHY DO LAKES in SD TURN GREEN IN

SUMMER?

When an ecosystem receives a LARGE inputof limiting nutrient (ie., fertilizer runoff) thepopulation increases dramatically = ___________

REMEMBERYOUR OLD BIO !

ALGAL BLOOM

Nitrates & phosphates from fertilizer/manure getwashed 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

http://sbt.blob.core.windows.net/storyboards/v1621335/eutrophication_thumb.png

Gulf of Mexico Dead Zone

http://www.ncat.org/nutrients/hypoxia/hypoxia.html

The DEADZONE forms each April, generally grows throughout the summer, reaching a peak in late July.

Gulf of Mexico Dead Zone

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

http://serc.carleton.edu/microbelife/topics/deadzone/index.html

https://nofishleft.files.wordpress.com/2010/11/coastal-dead-zones.jpg

NITRATES

PHOSPHATES

http://backtoessentialsllc.com/our-services/alkaline-therapy/