Water Quality Image Map


 


Understanding relationships:

The following graphing activities will demonstrate the difference between a direct relationship and an inverse relationship.   

Month
Temperature (C)
Temperature (F)
Dissolved Oxygen (mg/L)
January
10.6
51.1
8.1
February
9.8
49.6
8.2
March
11.9
53.4
7.0
April
13.4
56.1
6.3
May
15.5
59.9
5.0
June
17.8
64.0
4.6
July
21.9
71.4
4.1
August
26.6
79.9
3.1
September
24.8
76.6
3.7
October
21.0
69.8
4.0
November
15.0
59.0
5.2
December
12.2
54.0
6.9

Graph Temperature (oC) on the x-axis and Temperature (oF) on the y-axis.

Notice that these two scales for measuring temperature (Celsius and Fahrenheit) are directly related to one another.  In fact, you can use the following equation to convert from Celsius to Fahrenheit.   oF = 9/5 x oC + 32o

Next, graph Temperature (oC) on the x-axis and Dissolved Oxygen (mg/L) on the y-axis.

Notice that these two factors are inversely related to one another.  As temperature increases, the amount of dissolved oxygen in water decreases.  This relationship is best described by the following equation:  Dissolved Oxygen = -0.29 x  oC + 10.4

Note: the units for measuring dissolved oxygen are milligrams per liter.

Certain organisms require a minimum amount of dissolved oxygen to survive in water.  If water temperature is increased, the amount of dissolved oxygen will be decreased and some organisms will not be able to survive.

previous page of presentationnext page of presentation

1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12

Introduction | Objectives | Pre-Test | Presentation | Activity | Post-Test
PEER Curriculum | Water Quality Modules | Teacher's Pages | Standards