Laboratory Analyses

Laboratory Analyses

Turbidity was measured using a turbidimeter. The analysis was made by taking a sample of the water into one of the cuvettes provided, cleaning the surface of the cuvette with a thin film of silicone oil and a soft lint-free cloth, then placing the cuvette into the turbidimeter. Each reading was taken four times to ensure accuracy. The turbidimeter does not need frequent calibration, therefore the treatment group has never calibrated the instrument.

Conductivity and pH were measured using a pH/Conductivity sensor, which must be calibrated separately for both pH and conductivity before use. This is done by placing the sensor into several solutions of varying pHs/conductivities. The sensor is then placed approximately 5 cm below the surface of the water/sample and remain there until the reading becomes stable (between 30 seconds and several minutes). The sensor must be rinsed with distilled water in between readings and once the measurement is done.


Dissolved oxygen was measured by using a portable dissolved oxygen meter. The sensor was placed approximately 5 cm below the water/sample surface and pressing the green button. Once the "Stabilizing" text disappears, the reading can be recorded. Appendix 2 9 (27) This sensor does not need to be calibrated. The sensor must be rinsed with distilled water in between readings and once the measurement is done.

Phosphorous was measured by taking 3.5 mL of sample (preferably by pipette) and heating it in a thermostat for 60 minutes at 100°C. Once cooled, 0.2 mL Reagent B (LCK 349 B) is pipetted into the cuvette. The cuvette should be inverted and thoroughly cleaned before evaluation. For accurate readings, the pH of the sample should be between 2 - 10, and the temperature between 15 - 25 °C. The sample was within these limits therefore the result is accurate.