9.4: Chemical Monitoring and Management

Dissolved Ions

The existence of dissolved ions in water is what makes water conduct electricity as pure water is a poor electrical conductor. Dissolved ions in water are inevitable and many are completely natural. Low levels of many ions are essential for some fresh water aquatic life. When the concentration of dissolved ions reaches a certain level the water is no longer considered to be fresh and it becomes saline/salt water. Most dissolved ions are from humans and get into the water through human waste that is dumped into rivers, ponds and other fresh water bodies, including groundwater.

There are many ions which are frequently found in natural fresh water and each ion has a different effect on the water; some effects are harmful and some simply create a bad taste in the water. The two most destructive ions are nitrogen and phosphorus both of which are two of the nutrients found in most fertilisers. When it rains these nutrients join with the water and dissolve and either seep into the groundwater system or run-off as stormwater flow into creeks, rivers, lakes or the ocean. This dramatically increases the amount of theses ions in our fresh water system. Below is a table of dissolved ions commonly found in water and their basic effects.

Table 1: Dissolved ions commonly found in water and their basic effects

Dissolved Ion	Basic Effects
Phosphorus	Algal growth
Nitrogen	Algal growth (eutrophication), methemoglobinemia (Blue Baby Disease)
Chloride	Effects taste
Calcium	Scale and incrustation in pipes and machinery
Sulphate	Effects taste, gastro-intestinal problems
Iron	Effects taste, colour change
Manganese	Effects taste, colour change