Shallow Groundwater Chemistry

Rainwater infiltrates into the soil and interacts with carbon dioxide in soils to become acidic. This acidic water then comes in contact and dissolves minerals in the soil. Eventually the water becomes neutral to mildly alkaline. This process is even more enhanced when cation exchange (in this case calcium for sodium) takes place.

Groundwater interacts with the soils and other materials as it flows through them, becoming more mineralized over time, and distance.

Some earth materials, such as glacial tills or marine shales, contain soluble minerals that dissolve relatively rapidly in groundwater and can cause deterioration in groundwater quality at a shallow depth.

Groundwater with the correct mineral content can dissolve limestone to form underground caves. It can also result in calcite deposits developing in well screens. Other important minerals are dissolved iron and manganese, as these tend to form scales and films in water systems when the water is removed from the aquifer and exposed to oxygen in the atmosphere.

Deep groundwater also can destroy pathogens that depend on oxygen, as oxygen is not present in groundwater with a long residence time.

Some chemical parameters, such as sodium, chloride, sulphate, fluoride, nitrate, and a number of trace metals vary in concentration from aquifer to aquifer and can occur at levels that pose a health risk to people if the water is not treated to reduce the concentrations to appropriate levels.

The public Health Units in Alberta are responsible for advising individual well owners regarding the suitability and safety of the water from their individual household wells. The advice they provide is based on a water sample taken from their well that has been analysed by an approved analytical company. The advice includes treatment required to ensure safe drinking water. Alberta Environment regulates larger municipal water systems that utilize groundwater as the source of drinking water. Municipal wells are checked routinely to determine their water quality.

A network of provincially owned monitoring wells has been periodically monitored for water chemistry. The wells have not been sampled for water quality for over five years, however, future sampling is being planned. This monitoring is intended to provide scientific information regarding the variability of chemical constituents within aquifers in the province.

Groundwater has a relatively constant temperature year-round. Near the ground surface water temperatures would be close to the mean annual temperature of the atmosphere. The temperature usually increases with depth. In some aquifers, vertical flow results in mixing that results in a constant temperature over great depths.

As groundwater temperatures are relatively constant they can be used in heat exchangers for use in air conditioning in summer and heating in winter.

Hot springs can also be a source of heat and energy, however, in Alberta there are too few to be commercially significant. The main hot springs in Alberta are the Banff Sulphur Hot Springs and the Miette Hot Springs.