AP Lab #12  Dissolved Oxygen & Aquatic Primary Productivity
Sponsored Links
This presentation is the property of its rightful owner.
1 / 70

AP Lab #12 Dissolved Oxygen & Aquatic Primary Productivity part I PowerPoint PPT Presentation


  • 110 Views
  • Uploaded on
  • Presentation posted in: General

AP Lab #12 Dissolved Oxygen & Aquatic Primary Productivity part I. In an aquatic environment, O 2 must be in a solution in a free state before it is available for use by heterotrophic organisms….

Download Presentation

AP Lab #12 Dissolved Oxygen & Aquatic Primary Productivity part I

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


AP Lab #12 Dissolved Oxygen & Aquatic Primary Productivity part I


In an aquatic environment, O2must be in a solution in a free state before it is available for use by heterotrophic organisms…


In an aquatic environment, O2 must be in a solution in a free state before it is available for use by heterotrophic organisms…

The concentration of O2, and its distribution in an aquatic environment (the pond, ocean etc.), are directly dependent on factors that greatly affected by biological processes!

In the atmosphere … O2 is abundant


Terrestrial = 200 mL O2/ 1 L air

Aquatic = 10 mL O2/ 1 L water

WHY???

In an aquatic environmentO2 is NOT as abundant as in a terrestrial…


Terrestrial = 200 mL O2/ 1 L air

Aquatic = 10 mL O2/ 1 L water

O2distribution in water depends on: currents, winds, tides etc. mixing it up !

O2 diffuses 300,000 X’s fasterinair than water


Terrestrial = 200 mL O2/ 1 L air

Aquatic = 10 mL O2/ 1 L water

O2 distribution in water also depends on: pH,


Terrestrial = 200 mL O2/ 1 L air

Aquatic = 10 mL O2/ 1 L water

O2 distribution in water also depends on: salinity,


Terrestrial = 200 mL O2/ 1 L air

Aquatic = 10 mL O2/ 1 L water

O2 distribution in water also depends on: elevation


Terrestrial = 200 mL O2/ 1 L air

Aquatic = 10 mL O2/ 1 L water

O2 distribution in water also depends on: temperature


HIGHER O2 (DO) CONCENTRATION (ppm) at:

“Help - I am suffocating!!!”

neutral pH

low elevation

low salinity

low temperature


Terrestrial = 200 mL O2/ 1 L air

Aquatic = 10 mL O2/ 1 L water

O2 distribution in water also depends on: partial pressure of O2 in the air above the water !


LESS O2 IN WATER AT HIGHER ELEVATIONS

THAN AT LOWER ELEVATIONS


You could think about the amount of O2 in the air @ these locations…


Terrestrial = 200 mL O2/ 1 L air

Aquatic = 10 mL O2/ 1 L water

O2 distribution in water also depends on: amount (rate) of photosynthesis & respiration


photosynthesis increases the D.O. (ppm) !

respiration decreases the D.O.(ppm) …


measuring D.O. is a determiner as to whether the biological activities requiring O2 are occurring (respiration)

Indicator of health of lake !


Which environment has the greater concentration of dissolved oxygen: Explain.

or a clear pond?

a heavy algal mat?


Clear water holds more dissolved oxygen than water with a heavy algal mat. Although photosynthesis in the algal mat will produce a great deal of oxygen, the decay of so much organic matter will result in a net depletion of oxygen due to DECOMPOSERS.


??? SAY WHAT????


DECOMPOSERS w/ be in a large amount BECAUSE THE ALGAE WILL EVENTUALLY DIE... The decomposers w/ come on the scene and will USE THE OXYGEN, thus decreasing the amount of DO


Just HOW do you measure D.O.?

Winkler

method


Just HOW do you measure D.O.?

via.

titration


WINKLER METHOD to determine D.O.

1. Add alkaline iodide & manganous sulfateto a water sample.

Manganous hydroxide will be produced.

This will be acidified, & will spontaneously be converted to a manganese compound by the O2 in the water sample


WINKLER METHOD to determine D.O.

2. Add alkaline potassium iodide azide (KOH)to the water sample.

Iodine will be released -> H2O will turn yellow

**The quantity of free iodine is equivalent to the amount of D.O. in the water.**


WINKLER METHOD to determine D.O.

3. A starch indicator is then added… to determine amount of iodine via. titration

H2O will turn purple

You remember, titration is adding a substance of known concentration to a solution containing a substance of unknown concentration… until a specific reactions completed and a color change occurs.


WINKLER METHOD to determine D.O.

4. The amount of D.O. can then be determined by titrating aportion of the sample with sodium thiosulfate until a colorless endpoint is reached.


AP Lab #12 Dissolved Oxygen & Aquatic Primary Productivity part I


MEASURING D.O.

In order to measure how much oxygen water can hold (the saturation) you will also need to be able to read a nomograph:


the percent oxygen saturation for a water sample at 10oC that has 7mg O2/L is 45% saturation

nomograph


the percent oxygen saturation for a water sample at 25oC that has 7mg O2/L is 65% saturation

nomograph


Day 1

temp. effect

4 degrees C

25 degrees C

30 degrees C

Goggles and gloves MUST be worn


AP Lab #12 Dissolved Oxygen & Aquatic Primary Productivity Day 2


Day 2 we will compare D.O. values in water samples exposed to differing amounts of light


Primary Productivity

the rate @ which biomass is produced & stored (by autotrophs) via. photosynthesis in an ecosystem


Primary Productivity

amount of organic compound formed from photosynthesis

amount of organic compound used by respiration

-

Aquatic P.P.


Primary Productivity

amount of organic compound formed from photosynthesis

-

amount of organic compound used by respiration

Net Primary Production


Primary Productivity can be measured by:

*rate of CO2 utilization

*rate of sugar formation

(glucose produced)

*rate of O2 production in the light


Primary Productivity can be measured by:

can calculate the amount of carbon that has been “bound” in organic compounds over a time

via. RATE OF O2 PRODUCTION


You will monitor the effect of varying light levels on D.O. in an algae-rich water culture


Just HOW do you measure primary productivity?

Light-Dark

bottle O2

method


Light-Dark bottleO2method to determine primary productivity

1. Measure D.O. concentration in an initial sample CONTROL TO COMPARE

2. Measure D.O. concentration in a dark sample JUST CELL RESPIRATION

3. Measure D.O. concentration in a light sample PHOTOSYNTHESIS & CELL RESPIRATION


Light-Dark bottleO2method to determine primary productivity

RESPIRATION -> initial sample - dark sample

GROSSPRIMARYPRODUCTION -> light sample+ amount used in dark sample

NETPRIMARYPRODUCTION -> light sample- dark sample


Day 2

primary

productivity


Day 2

primary

productivity


Day 2

primary

productivity

3. Each bottle will have the % light it will receive..


Day 2

primary

productivity

3. Each bottle will have the % light it will receive..


Day 2

primary

productivity

3. Each bottle will have the % light it will receive..


Day 2

primary

productivity


L - I = Net Productivity

I - D = Respiration

L - D = Gross Productivity

note: dark is a negative number

L

DO (mL O2 / L)

Net Productivity

I

Gross Productivity

Respiration

I = Initial Bottle L = Light Bottle D = Dark Bottle

D

Incubation Time (hours)

24

0


net productivity + respiration = gross productivity

(light - initial) + (initial - dark) = gross productivity

(light) + (- dark) = gross productivity

light - dark = gross productivity

you subtract

to get gross

b/c:


this number will be negative


this number will be negative


How do lakes age?


OLIGOTROPHIC


OLIGOTROPHIC

  • Very little nutrients (nitrogen & phosphorus

  • Deep

  • Clear

  • Very little algae

  • Colder

  • Highly oxygenated


A oligotrophic lake

Oligotrophic lakes are very low in nutrients, so few algae grow and the water is very clear.

Oligotrophic lakes are biologically less productive lakes (they have the lowest level of biological productivity), and support very few plants and fish.


MESOTROPHIC

  • Medium amount of nutrients (nitrogen & phosphorus)

  • Clear

  • Algal blooms in late summer on top~ D.O. higher on top

  • Warm on top /Colder on bottom

  • Higher decomposition rate on bottom~ D.O. lower on bottom


EUTROPHIC

  • High amount of nutrients (nitrogen & phosphorus)

  • Shallow/ Murkey

  • Algal blooms b/c of nutrients / high fish

  • Higher decomposition rate on bottom~ D.O. lower all over


EUTROPHICATION

a natural process that occurs in an aging lake or pond as that body of water gradually builds up its concentration of plant nutrients.


EUTROPHICATION

Cultural or artificial eutrophication occurs when human activity introduces increased amounts of these nutrients, which speed up plant growth and eventually choke the lake of all of its animal life.


A eutrophic lake


  • A eutrophic lake is shallow with high nutrient content.

  • The phytoplankton are very productive and the waters are often murky.

  • Ecologist use the term to describe relatively productive habitats and communities having good nutrient supply and to separate them from unproductive oligotrophic ones, characterized by a nutrient deficiency.


A eutrophic lake


A oligotrophic lake


SPRING TURNOVER


  • Login