Student Research Reports
Effect of pH on Dissolved Oxygen and Nymphaeaceae Decay
Organization(s):St. Patrick Catholic High School
Country:United States of America
Student(s):Gavriella Persing
Grade Level:Secondary School (grades 9-12, ages 14-18)
GLOBE Teacher:Emily Cloud
Contributors:
Report Type(s):International Virtual Science Symposium Report, Standard Research Report
Protocols:Dissolved Oxygen, pH
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Language(s):English
Date Submitted:03/11/2021
GLOBE Water Testing measures several different characteristics of water which can determine its ability to be used for purposes such as drinking. One of these characteristics is dissolved oxygen. The pH of water can influence how effective the rate of photosynthesis and respiration are, as each process has an ideal pH based on the organism performing it.
Five water samples and lily pads (Nymphaeaceae) were gathered, and each sample was modified to a certain pH level: 3, 4, 5 (original), 6, and 7. The samples were monitored over the course of 10 days, measuring dissolved oxygen levels of each sample as well as its lily pad diameter.
The highest dissolved oxygen level was pH 5 (6.868 ppm), then pH 6 (4.848 ppm), then pH 7 (4.040 ppm), then pH 4 (1.616), and lastly pH 3 (0.0 ppm). Increases in dissolved oxygen could also potentially be due to photosynthesis of microorganisms living in the samples. Additionally, any mold that may have grown in the samples over time could have lowered the dissolved oxygen levels because of its own metabolic processes.
The total percent change in lily pad diameter was 3.49 for pH 7, 2.36 for pH 6, 1.01 for pH 5, 0 for pH 4, and -2.14 for pH 3. Tonicity differences may have led to osmosis in the lily pads, contributing to growth. Additionally, different pH levels could have been ideal conditions for photosynthesis, increasing lily pad size.