Monitoring and Management > 5. Water >
Gather, process and present information on the range and chemistry of the tests used to:
- identify heavy metal pollution of water
- monitor possible eutrophication of waterways
- Heavy Metal: A metal with a relative density of 5.0 or higher.
- Heavy metals, such as mercury and lead, can cause various health problems.
- The heavy metal pollution of water can be tested using:
- Atomic absorption spectroscopy, using a light source specific to the heavy metal being tested.
- Flame tests.
- Sodium sulfide solution, which can be added to a highly concentrated acidified or basified water sample (heavy metal ions react with sulfide ions to form sulfide precipitates):
- If a precipitate is formed when the sample is acidified, then one or more of the following is present: lead, silver, mercury, copper, cadmium, arsenic.
- If a precipitate is formed when the sample is basified, then one or more of the following is present: chromium, zinc, iron (III), nickel, cobalt, manganese, aluminium.
- Eutrophication: The abundant growth of aquatic plants due to nutrient-enriched conditions, in particular, nitrate and phosphate enriched conditions.
- The aquatic plants that grow abundantly in eutrophication eventually use up all of the available nutrients that they require and die.
- The plants decompose, and in doing so, use up all dissolved oxygen.
- After using all oxygen, they decay anaerobically, resulting in chemicals that kill all remaining life.
- The decay causes sediment at the bottom of the water body.
- The mains sources of nutrients that cause eutrophication are:
- Sewerage.
- Fertiliser.
- Nitrate and phosphate are monitored in waterways vulnerable to eutrophication.
- The nitrogen-phosphorus ratio of waterways is often monitored, with the EPA recommending a ratio of less that 10:1.