Negligible Concentrations of Metals

Metals are micronutrients for aquatic plants and animals. They are required in trace amounts to build strong cell walls and membranes and contribute to cell growth, photosynthesis and respiration.

Metals occur naturally in aquatic systems, leaching into the water from rocks, soils and bottom sediment. Except for aluminum, the small amounts of metals found in the Rideau River during the Project were well below the acceptable maximum levels set by the Canadian Water Quality Guidelines for Freshwater Aquatic Life. [11] Aluminum levels were slightly above the maximum acceptable level in 5 of the 36 samples taken in 1999.

A species of Potamogeton.

It is not known why aluminium concentrations were higher in some samples. It is possible that the higher levels may be laboratory or sampling errors.

In some Ontario waterbodies, metals have become pollutants because they are present in concentrations that are greater than the trace amounts required by aquatic life. Industrial activities may release metals into the water through their effluent. Fortunately, there are no industrial activities along the Rideau River. Acid rain also contributes to higher levels of metals in a waterbody because it accelerates leaching from rocks and soils.

	Mud amnicola, Amnicola limnosus. Dissolved Salts: Needed by Bacteria Dissolved salts, called ions, are important, naturally occurring components of freshwater. They enter the water from eroded rocks and soil. Bacteria require the salts in order to synthesise proteins, which are necessary for plant and animal growth. However, if the ion level is too high, aquatic plants and animals may have difficulty developing. The Canadian Water Quality Guidelines for Freshwater Aquatic Life [11] does not comment on levels of dissolved salts in natural bodies of freshwater because naturally concentrations vary widely, depending on the surrounding rocks and soil. No abnormalities were noticed in Rideau River water samples taken during the Project. Analysis has revealed that concentrations of the sodium and chlorine found in the salt used on nearby roads were small.