Water Quality Index using Microworlds [*]
by Orlando Mihich and Students
* Click the Start button and
move the pointer to a value on the abscissa.
Introduction
The goal of this ongoing project is to aid students in developing into citizens who possess the knowledge, skills, and attitudes to engage in environmentally responsible behaviors. Booker T. Washington, Middle School 54, is located on the Upper West Side of Manhattan, and the Hudson River, one of the most beautiful sites in New York, is in walking distance from the school. The question is: How is the Hudson River doing? With a yearly budget of $250-300, the project began three years ago.
Project Description
Once a week, a group of seventh and eighth grade students,
“The Water Watch Team,” visits the Boat Basin on the
Hudson River, at the 79th Street Marina. Here, students record air
and water temperatures, take pH readings, determine the water
clarity and dissolved oxygen levels, and prepare a sample for the
five day “biochemical oxygen demand” test. Sewerage
pollution is tested using a Coli-count sampler. A water sample is
brought back to school to determine levels of nitrates,
phosphates, and solids.
In their work, students follow an Internal Manual
compiled from different sources: the literature which comes with
the suppliers’ test kits, various electronic encyclopedia,
but mainly from the Field Manual for Water Quality
Monitoring. The Internal Manual was written in part by
students and contains a general section on the world’s
rivers, their history, the watershed, and some information on the
utility and history of the Hudson River. For the most part, the
test procedures in our “Internal Manual” conform to the
procedures outlined in the “Field Manual for Water Quality
Monitoring.” Other procedures requiring open flame
burners, filtration, the use of sulfuric acid, or other harsh
chemicals have been modified. For example, the Coliforms test is
performed using the pocket-size Millipore Coli-count sampler.
Prepared on location, the sampler is incubated at 35° C for
22-24 hours in the school’s lab.
Following is a brief description of the importance of the nine
tests.
1. Dissolved Oxygen (DO).
Dissolved oxygen is a measure of the health of a body of water.
The absence of oxygen indicates severe water pollution.
2. Fecal Coliform. Fecal
coliform levels are monitored, because of the correlation between
fecal coliform and pathogenic bacteria, and viruses that cause
diseases.
3. pH. Most natural
waters have a pH value from 5.0 to 8.5. Higher or lower levels are
unsuitable for most organisms.
4. Biochemical Oxygen Demand
(BOD) [5-days]. Biochemical oxygen
demand is a measure of the quantity of the oxygen that disappears
from the water due to the decomposition of organic matter.
5. Temperature. Thermal
pollution from industries, urban runoffs, soil erosion and
deforestation affect the amount of dissolved oxygen and rate of
photosynthesis.
6. Turbidity. Increased
amounts of suspended solids reduce the transmission of light and
cause waters to become warmer, with a consequent drop in oxygen
levels.
7. Phosphates.The amount found
in healthy water is generally small, not more than 0.1 ppm. Larger
amounts of phosphates usually wipe out the river’s fish
population.
8. Nitrates. The presence of
excessive amounts of nitrogen promotes plant growth and decay,
which in turn increases biochemical oxygen demand.
9. Total Solids. High
concentrations of suspended solids reduce water clarity, and
contribute to an increase in water temperature and a decrease in
photosynthesis.
Students enter all test results in a ClarisWorks spreadsheets and
generate charts for a discussion of results. Once all the nine
tests are completed, students use MicroWorlds to find the
Overall Water Quality Index.
Computing the Overall Water Quality Index
The Water Quality Index (WQI) is a standard index developed by
the National Sanitation Foundation to compare rivers’ waters.
The WQI ranges from 100, for Excellent Water Quality, to 0
for Very Bad Water Quality. To obtain the WQI number, it is
necessary first to find the Q-value, the quality value, for
each test. This is done with a series of nine “weighting
curves,” one for each test. Once found, the Q-value is
multiplied by a “weighting factor,” to obtain the
Total Q-value for the test. The sum of all Total Q-values
gives the Overall WQI for the testing site.
During the first year of testing, students computed the Q-value
consulting the charts provided in the “Field Manual for Water
Quality Monitoring.” ClarisWorks was employed to find Overall
WQI. The second year, students recreated all the nine diagrams in
LogoWriter, and wrote a program to find the Q-value by just
positioning the turtle on the abscissa and typing “find”
in the command center. At the same time, we realized that several
“weighting curves” could be changed and adapted to local
conditions; e.g.,Total Solids never exceeded 20 mg/L, so we
changed the existing diagram’s values of 0 mg/L to 500 mg/L
to values going only from 0 mg/L to 100 mg/L; the curve was
redrawn accordingly. Now, we were able to position the turtle more
accurately on the abscissa and achieve more precise
results.
At present, with the introduction of MicroWorlds it is feasible to
find the Q-value, the Total Q-value, and the Overall Water Quality
Index without switching to ClarisWorks.
Discussion of Results for the school year 1994-1995
For the school year 1994-1995, the WQI ranged from MEDIUM to
GOOD. Fecal coliform bacteria exceeded 200 colonies/100 mL, and
the Hudson River’s water did not meet the state standard for
total body contact such as swimming. Dissolved oxygen levels were
healthy, above 4 mg/L. Biochemical Oxygen Demand levels were
higher than expected, indicating the presence of large amounts of
oxygen consuming microorganisms.
On May 18, 1995, the “Water Watch Team” students were
awarded the New York Citywide and Boroughwide first prizes for
their work in “The Hudson River Water Watch Project” as
part of the Citywide
“Team-Up-To-Clean-Up”
Competition. In December 1995, “GREEN,” the journal for
the Global Rivers Environmental Education Network published an
article describing the above work.
Results for the school year 1995-1996
MicroWorlds as a programming tool
Students position the pointer for the % of DO on the abscissa,
then click on the FIND button. This turtle, t3, finds the Q-value
for DO, using the procedure, find.DO.
The pointer travels to the curve, turns toward, and continues
to the ordinate. The Q value shows in the active dialog box.
Here, the Q-value is multiplied by the Weighting Factor (W.F.)
to obtain the Total Q-value. To continue students click the ARROW
button. The new Biochemical Oxygen Demand page comes up. In the
dialog box, the Q-value for Dissolved Oxygen is displayed with a
plus (+) sign. The sum signs are added all throughout with each
new result. The last page computes the Overall Water Quality
Index.
<<Positions t1 at the origin
of the diagram;
Creates the reference turtle "zero.Q;
Creates the textbox "Q-DO.>>
to start.DO
t1, st
pu setpos [-225 -60]
setsh "pointer1
setsize 20
make "a pos
newturtle "zero
ht
pu setpos :a
newtext "Q-DO [100 140] [120 155]
settc "125
setstyle "bold
setfontsize 12
end
<< Prevents from accidentally clicking the "FIND" button
when the Total Q-value is already found, and
when the Total Q-value is not found yet.
Finds the Q-value.>>
to find.DO ;button
if alert.DO = 1 [alert.sound stop]
ifelse (ask "t1 [pos]) = :a [announce [Introduce
your result on the abscissa.]] [DO]
end
to DO
t1,
seth 0
if colorunder = 15[seth 270 pu fd 10 go
q.DO
stop ]
pu fd 1
DO
end
<<Rounds and adjusts the Q-value
reading for the existing 20 * 20 grid;
Inserts the "weighting factor;"
Gives the Total Q-value.>>
to Q.DO
talkto "Q-DO
insert round value / 2
insert char 32
insert "|* 0.17|
insert char 32
insert "=
insert char 32
insert round (value / 2) * 0.17
end
to alert.DO
talkto "Q-DO
output textcount "Q-DO
end
<<Selects and copies only the Total
Q-value>>
to move.value.DO
top
select
cd
repeat 2[cb]
cut
top
select
cd
copy
end
<<Prevents getting the next page
before Q-value is found;
Copies the Total Quality Value;
Removes the textbox;
(leaves "zero.Q turtle in place)
Gets and starts the next page>>
to end.DO ;button
ifelse alert.DO < 1 [announce [Please, find
Q-value first.]]
[move.value.DO remove "Q-DO getpage
“|Biochemical O2 Demand| start.BOD]
end
to go
setsh "pointer2
if colorunder = 55 [stop]
pu fd 2
go
end
to value
t1, output distance "zero
end
to alert.sound
sosumi ;plays the Mac “sosumi” sound
end
After all test results have been computed, the final page gives
students the Overall Water Quality Index when they click the FIND
button.
Water Quality Index (WQI) Procedures
<<Creates two new textboxes:
"Total displays the numerical sum of all "Total Q-values"
generated throughout the project, and "|Water Quality| displays
the water quality range, from “Excellent” to “Very
Bad” according to the numerical value>>
to start.WQI
t1,
setsh "pointer2
pu setpos [-50 120]
newtext "Q-WQI [100 140] [120 155]
settc "125
setstyle "bold
paste
newtext "Total [100 -15] [120 30]
newtext "|Water Quality| [-200 140] [140 40]
end
to find.WQI ;button
if alert.WQI = 1 [announce [Please,
continue.]stop]
settotal run Q-WQI WQI
end
to WQI
name total "result
talkto "|Water Quality|
if :result = 100 [print "Excellent]
if :result = 90 [print "Excellent]
if and :result > 90 :result < 100 [print
"Excellent]
if and :result > 70 :result < 90 [print "Good]
if :result = 70 [print "Good]
if and :result > 50 :result < 70 [print "Medium]
if :result = 50 [print "Medium]
if and :result > 25 :result < 50 [print "Bad]
if :result = 25 [print "Bad]
if and :result > 0 :result < 25 [print "|Very
Bad|]
if :result = 0 [print "|Very Bad|]
end
to alert.WQI
talkto "Total
output textcount "Total
end
to end.WQI ;button
ifelse alert.WQI < 1 [announce [Please, find the WQI
Index.]]
[dolist [i [zero.Q Q-WQI Total |Water
Quality|]] [remove :i]
Solids
getproject "WWT+1]
end
The last instruction, getproject “WWT+1 brings up a
page with a picture of
Next are ClarisWorks sample charts with a brief discussion by the
students.
The above chart clearly shows that gases, like oxygen, dissolve
more easily in cooler water than in warmer water. In addition,
healthy levels of DO, above 4 mg/L, were found for the Hudson
River at the 79th Street location during the testing period. By:
Laura Guzman and Loamy Hodge.
Water temperatures, in general, follow air temperatures , but
water, a heavier fluid, responds less drastically to variations in
temperature. By: Alejandro Cruz Ruez Wilmer.
The diagram shows that, with several exceptions, most of the
oxygen is used up in the five-day test by organic matter and
microorganisms in the water. By: Michael Estrada.
Bibliography
Field Manual for Water Quality Monitoring; Mark K.
Mitchell and William B. Stapp, 1994. GREEN, 721 E. Huron Street;
Ann Arbor, MI 48103
MicroWorlds, Hypermedia Project Development and Logo
Scripting; Sharon Yoder, ISTE 1996
This project owes its continuing success to the enthusiastic involvement of Michael Estrada as student in charge, and the following students: Carolina Alcantara, Nestor Amaya, Socrates Brito, Marilyn Carabajo, Alex Estevez, Rufino Estevez, Lilliana Estrella, Tracy Fields, Laura Guzman, Loamy Hodge, Sam Lazarus, Alexandria Matos, Wilfredo Pichardo, Patrick Mahaney, Haydee Pimentel, Aaron Riccio, Wilmer Ruez, and Maria Solares.Orlando Mihich is a computer teacher at Booker T. Washington, MS 54, Community District 3, New York City. He has taught Science and Logo for the past 13 years. Prior to that he was a chemical engineer in the surfactants and cosmetic industries. He can be reached by e-mail at OMihich@aol.com.
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