Teaching Materials for Water Analysis Using Image-Processing Software and a Scanner : Determination of Trace Amounts of Nitrite Anion in River Waters

Abstract

We developed a new image-processing software to analyze the color information (RGB value) of digital image files downloaded from scanners and digital cameras onto a personal computer. Using this software and a scanner, we obtained a good linear relation between the concentrations of nitrite anion solution colored with a Saltzman reagent and the levels of absorption obtained from the RGB values of each digital image file of the solutions. Thus, we can determine trace amounts of nitrite anion in water by this method. In integrated study classes for sixth grade students in a public elementary school, determination of chemical oxygen demanded by the conventional pack test and that of nitrite anion by our method were conducted in order to investigate the pollution levels of samples of river water. All students carried out both experiments, and they were able to determine trace amounts of nitrite anion in river water by our method with high accuracy. It is also suggested by the answers to questionnaires that the student's experience of determining trace pollutants enhanced the students' positive perception of environmental study and that they thought that this software was a useful teaching tool for environmental study.