Human activity continues to expand and develop new areas across the entire planet. In this world of constant growth, environmental monitoring has become a crucial aspect of remedial and preventative work to ensure that our planetary ecosystem remains healthy and safe and continues to operate in equilibrium.
Environmental monitoring is the name given to the various investigations, tests and processes that can be carried out to monitor the conditions of the local environment. This allows scientists to observe natural changes, as well as any impact on environmental quality as a result of human activity.
Specific information that environmental monitoring can provide can include recording baseline quality, identifying environmental trends, uncovering any variations and confirming whether environmental goals have been achieved. These insights help us to minimise or prevent any of the negative effects of human activity. This constitutes a central pillar of the environmental impact assessments commonly used to decide whether projects should be allowed to proceed or not.
The Importance of Water Quality Monitoring
Analysing water quality is essential for ensuring that rivers, lakes, oceans and estuaries are maintained in a sanitary and safe condition. Chemical conditions are key, with analysis focussing on levels of pH, nutrients, dissolved oxygen, pesticides, oils and heavy metals. Also used to determine quality are physical conditions such as temperature, flow, sediment and erosion. Biological assessments of flora and fauna must also be taken into account.
There are certain challenges posed by any attempt to obtain reliable laboratory data, however. Appropriate lab practices, sampling procedures and experiment design are essential if useful data is to be collected. The instrumentation used in monitoring and data collection is also crucial. There exist wide arrays of equipment and parameters for water monitoring, so when choosing which instruments to use, the sampling method should first be considered.
If your plan involves pumping a water sample to the surface, it is imperative to use a sample container deep enough for instrument probes to be fully submerged when taking a reading. Likewise, if you intend to lower the water quality instrument down into a well, take care that the casing diameter of the well is wide enough to accommodate the probes, and that the cables attached to the instrument are sufficiently long enough to reach your desired depth. Note that wells with extreme levels of contamination could damage your instruments.
Multi-Parameter Water-Monitoring Instruments
Whilst different instruments are required to monitor and record different parameters, there are laboratory instruments designed to measure multiple parameters at once.
Aquifer Sampling: Pump and Slug Tests
Pump and slug tests are utilised to discover aquifer characteristics such as hydraulic transmissivity, storativity and conductivity. A slug test involves the insertion into a well of a pressure transducer capable of monitoring changes in water level elevation. The ‘slug’ – an object designed to displace a set amount of water – is dropped into the well. The pressure transducer detects and records the increase in water elevation. As water flows back into the aquifer, the water level equilibrates. The pressure transducer records the time and rate of flow. Pump tests work along similar lines but use multiple wells.
Low Flow Sampling
Flow-through cells are usually necessary for low flow sampling. This type of cell consists of a chamber with inlet and outlet channels for water to be pumped through, into which the water quality monitoring instrument’s probes are inserted. The consistent flow of water means that the instrument is constantly exposed to fresh samples from the well. This allows for stabilisation over time of the parameters being measured, making for a good overall representation of the quality of the water in the well.