Too Much O2 Or Too Little?

1C.5 You Decide

Too Much O2 or Too Little?

Name______Date______
Partner______
Purpose : In this activity you will be given data about the oxygen levels in the Snake River. You job is to analyze the data and find whether or not there is any indication of the cause of the fishkill in Riverwood.
Directions : Each team of 2 is to read the directions and work together on the problems. Only 1 set of graphs per team is needed but written answers and calculations should be done individually. When writing answers use sentences and be as clear as possible
Introduction Joe Fisker of the County Sanitary Commission has taken measurements of the dissolved oxygen(D.O.) in the Snake River for the last 18 months. The Sanitary Commission measures and records dissolved oxygen(D.O.) to determine the quality of water in the river. Fisker takes measurements daily at 9AM from under the bridge near the Riverwoods Hospital. at a water depth of .5 meters. In addition to the D.O. level Fisker measures the temperature of the water. Using these 2 measurements Fisker can determine how saturated the water is with D.O.
Below is date for the year before the fish kill. (Table 1.6) Also included is data for the three summer months before the kill which occurred on August 31st.(Table 1.7)
Graph #1 : Choose scales on the axis of the graphs to use as much of the paper as possible. Title the graph as "Monthly O2 Data" Label the x -axis as "Temperature, oC" and y-axis as "D.O. Concentration, ppm". Plot the points in table 1.6 place a  around each of the 12 points. Connect these points, starting with January. On the same graph plot the three points for the months before the kill(Table 1.7). Place a around these points. Connect the three.
Data Analysis of Graph #1
1. Explain the shape of the data form table 1.6
2. Explain the reason why there is a different average D.O. level in December and June
3.) Why are the D.O. concentrations similar in March and November?
4. Explain the difference between the average D.O. levels for August last year (table 1.6) and August of this year (table 1.7)
Graph #2 In September right after the fish kill, the Environmental Protection agency sent Marilyn Crocker to make D.O. concentration measurements in the Snake River on an hourly basis for 1 day. The goal was to find any short term changes in either the temperature or D.O. Marilyn Crocker took the measurements at the same location as Fisker.
Her data is shown in Table 1.8 and has been plotted for you in Graphs 1.22/23 (pg.52 & 53). Look at these graphs carefully.

Graph # 2 Analysis
1. Compare the nighttime to daytime D.O. levels
2. What is the relation between the rivers temperature and the D.O. level.
3. Explain why the relation between temperature and D.O. is different than you would expect
4. Explain what could cause the D.O. to rise and fall as they do
5. Calculate the average temperature during this day______
(use Table 1.8)
Calculate the average D.O. level during this day ______
6. What provides more useful information about the river: the averages or the graphs______Why
7. Would it be acceptable to compare the averages(#5) for 1 day in September of this year with the total monthly average for September of last year(see table 1.6) ______Why/why not?
Saturation Level Data Look at table 1.9. This table tells the solubility of oxygen at different temperature. For example, if a water sample was at 15oC and contained 10.2 ppm D.O., it would be 100% saturated. If the same water had only 5.1 ppm it would be 50% saturated.

%Saturation = (ppm of Measured D.O./ppm of D.O. in Saturated) x 100

Calculation of % Saturation
On the next page use the above formula, measured D.O. values from Table 1.8, and the data from Table 1.9 in book (pg. 53) and proper tables to calculate the % D.O. saturation. Directions for the last column are below.

(Table 1.7)

Monthly D.O. Data(Table 1.6)

One day D.O. Data (Table 1.8)

Analysis of Saturation Data Certain levels of D.O. are acceptable for the health of fish. Use the information below and decide whether or not the % saturation is "acceptable" or "unacceptable" for fish:

125% or more - too high for many species to survive
(supersaturated)
124% - excellent for most fish
79% - satisfactory for most fish
59% and under - most species die

Snake River Dam Data The Snake River Dam is operated by the Riverwoods Power Co. The dam has three purposes: 1) it creates a reservoir for recreation and drinking water 2) it controls flooding on the river 3) it creates hydroelectric power.
When Joe Fisker learned that another fish kill had happened at the base of the dam 30 years ago, he decided to look at D.O. levels near the dam itself. Gates on top of the dam(see page 73) can be opened or closed to prevent flooding. Opening the gates increase the "flow rate" of the water. As more water flows from the dam, aeration happens at the base of the dam causing D.O. to rise. With the cooperation of the power company, Joe Fisker decided to run an experiment. He opened the gates different amounts(different flow rates of water) and measured the D.O. at the base of the dam. The temperature of the water that day was 19oC. Here is his data:

How Dam Flow Rates Effect D.O. Levels

Joe Fisker also was able to get data from the power company about the operation of the dam on the days near the fishkill, which occurred on August 31st. Here are the average daily flowrates before and after the kill:

Average Dam Flow Rates in Late August and Early September

Analysis of Dam Data
1. Does any of the data on the dam show that unacceptable levels of D.O. were present during Fiskers experiment______Support your answer with numbers
2.Does the data about the dam operation in August and September indicate
any possible problem______Explain
Summary
Consider all of the data presented in this project. State what is now known about the cause of the fishkill. You may point out either "what didn't kill the fish" or "what did kill the fish". Be complete