Water Quality Monitoring for environmental management - J David Cooper, David McNeil, Gareth Old and Jonathan Evans

Water quality of lakes and rivers encompasses a wide variety of attributes, not all of which may be obvious on a first encounter. A reasonably complete list includes:

• Temperature
• Dissolved solids. This includes a wide range of substances. Interest is usually in those substances having biological significance, including oxygen, nutrients (particularly NO3-, NO2-, P and K) or toxic species, but may also encompass measurement of substances which will allow the geochemical signature of the water to be determined and hence provide clues to its origin.
• Electrical conductivity
• Suspended sediment. This may be a pollutant in its own right, but also a vector for other chemicals, such as heavy metals, which bind to the particles. By studying the mineralogy of the suspended sediment, the origin can often be determined.
• Turbidity
• Colour
• Biological Oxygen Demand
• Dissolved oxygen
• Partial pressure of carbon dioxide
• pH
• Alkalinity
• Redox potential
• Microbes and viruses
• Microfauna & microflora
• Macrophytes and macrofauna

The appropriate definition depends heavily on the purpose for which one needs the information and will, typically, encompass a combination of several of these factors. Several of the items mentioned above are, themselves, composites of a number of possible candidates. For instance, there is an almost infinite number of chemicals which may be dissolved in water and also very many different biological organisms which could be present in the water. It is necessary, therefore, to focus on particular applications and / or technologies to make the task of writing this article manageable.