This site contains generic instructions for conducting water quality testing. Several different tests are described that can be conducted over short or long periods of time. The site explains how to gather and treat the data and has suggested questions for the students to see if they can properly analyze the data. The objectives are to familiarize students with real-world gathering of scientific data and data-gathering techniques, to give students practice with basic statistical analysis and graphing, and to give them a better idea of the nature of analysis, data collection, interpretation, and presentation. Educational levels: High school, Middle school

Kurt Hollocher

English

Digital Library for Earth System Education

Stream chemistry monitoring 
A long-term or short-term lab exercise 
by 
Kurt Hollocher 
Geology Department 
Union College 
Schenectady, NY 12308 
Introduction 
Surface water is very common in many parts of the world. It occurs as streams, rivers, ponds, lakes, rain 
and snow, rain puddles, and the Earth's oceans. There are many aspects of fresh surface water that lend 
themselves to study in labs in Earth Science, Biology, and Chemistry. This exercise was designed as an 
example for the short course that started this web site. As such, it contains a number of ideas and 
suggestions that may not be pertinent to the normal Earth Science classroom. Please feel free to pick and 
choose the topics you are most interested in for your class. 
Purpose: 
1. To familiarize students with a real-world gathering of chemical (scientific) data.  
2. To establish the current chemical composition of the water body under study (for the 
compositional parameters analyzed).  
3. To familiarize students with data-gathering techniques (simple field equipment, record keeping).  
4. To give students practice with basic statistical analysis.  
5. To give students practice graphing data that they gather.  
6. To give students a better idea of how the science is done: the nature of analysis, data collection, 
interpretation, and presentation.  
Materials: 
1. A variety of analytical equipment for the field. This can include thermometers, rulers for 
measuring water depth, flow meters, pH meters, conductivity meters, equipment to measure 
alkalinity, dissolved oxygen meters, turbidity (Seechi) disks, and possibly many others. Also 
possibly some plastic containers if more work will be done in the lab with microscopes or other 
analytical equipment. Field pH, conductivity, and dissolved oxygen meters cost ~$50 each, flow 
meters and Seechi disks can be home-made, and alkalinity equipment and chemicals cost only a 
few dollars a student with help from a local chemistry department or college.  
2. A surface water body, commonly a small stream or river, or a pond or lake with easy and save 
access.  
3. A calculator with statistical functions (average, standard deviation), or a computer with a 
spreadsheet program (these have basic statistical functions built in).  
4. Graph paper if data from previous analyses are available. 
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Procedure: 
1. Review the nature of surface water and the water body to be studied. Do any students live near the 
water body? Is is a drinking water supply in the local area? Is it used for navigation? Does this 
water body have any known history of flooding or pollution?  
2. Review the proper use of the equipment: how it works, what it measures.  
3. Travel to the site and collect the measurements. Each student should keep a record of the 
measurements made and samples taken while in the field.  
4. Return to the classroom and compile the data into a table (blackboard, paper sheets, or a computer 
spreadsheet).  
 
Measuring stream alkalinity (bicarbonate). 
Data table showing all analyses of this stream. There are gaps in the record, but this is typical 
for real data sets too. It is best, however, if the same water body is sampled regularly.
Sample date pH Temp. C Alkalinity as bicarbonate, ppm Total dissolved solids, ppm
Aug 2, 1990 7.9 19  2480
Aug. 16, 1990 8.1 19  1560
Aug. 23, 1990 8.1 19  1440
Aug. 29, 1990 8.0 20  1420
Sept. 19, 1990 8.0 20  1340
Sept. 27, 1990 8.1 17   
Oct. 5, 1990 7.7 19  560
Oct. 18, 1990 7.9 17  1360
Nov. 1, 1990 8.3 11  940
Nov. 15, 1990 8.2 6  930
Mar. 7, 1995 8.1 6 204 2138
Mar. 5, 1997 8.3 4 186 2860
Apr. 12, 1997 8.9 7 174 574
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What to do with the data: 
1. For numerical data, calculate the average. Then, calculate the standard deviation of the mean 
(average) for the numerical data. this value gives the 95% confidence range for each analysis. To 
put it another way, the average is the value of the analyzed parameter that is generally reported, 
and the 95% confidence range is a measure of the accuracy of the measurements. To put it another 
way, twice the standard deviation is the +/- range commonly reported for the average value.  
2. Compile and summarize any other information collected (tallys of organisms collected, 
descriptions of site appearance, sketches).  
3. If some of the same data is available from previous labs, have the students plot those on graphs, 
with time as the X-axis and the measured values in the Y-axis. This can show how the water body 
is changing over time (see below).  
4. Optional: prepare a report of the results for distribution to other classes in the school (writing, data 
presentation, and conclusions are similar to scientific research papers).  
5. The class measured a small range of the various parameters that can be measured (detailed 
chemical composition, organic compounds, bacteria counts). Discuss some of the other things that 
need to be measured before this body of water could be evaluated for a drinking water supply.  
 
Actual pH data plotted from the table above. 
Evaluation: what was learned from this exercise? 
1. Can the students explain what an average is?  
2. Lets say the students are given three values of alkalinity, 31, 28, and 30, that were measured at 
exactly the same time in the same place but by different people. Can they explain why the results 
are not exactly the same? Can they calculate (using an appropriate calculator) the 95% confidence 
interval for the average? Hint: if the average = 29.7, the 95% confidence interval might be +/- 1.5, 
so the 95% confidence range is from 29.7-1.5=28.2 to 29.7+1.5=31.2. Is a new value of 31.0 
statistically different from 29.7 within the 95% conficence limits? Can scientific data ever be 
perfect?  
3. What things need to be known about drinking water supplys other than the things the class 
measured?  
4. How would you design a program to determine of a small river was becoming more or less 
contaminated with salt from a road salt storage depot (salt, as a major contributor to the total 
dissolved solids, can be monitored using water conductivity or total dissolved solids calculated 
from conductivity).  
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Web links: 
? Union College Data Page: chemical analyses of water and rocks.  
? Geochemical Earth Reference Model: Chemical composition of different parts of the Earth, 
atmosphere, and oceans.  
? Water and other testing kits.  
 
Science labs web page 
Pedagogy web page 
  
Kurt Hollocher 
Geology Department 
Union College 
Schenectady, NY  12308 
U.S.A. 
  
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Stream Chemistry Monitoring

http://minerva.union.edu/hollochk/pedagogy/files/kh1.pdf

Stream Chemistry Monitoring

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