Measuring equipment for water quality is becoming increasingly advanced. Some meters can be equipped with up to 13 different sensors. But is it always necessary to measure so many? Which parameters should you investigate in which situation? In this article we will examine various water problems and their corresponding parameters.
When measuring water quality, it is first important to determine the question and the objective. Which possible problems are being investigated? And is a spot-check sufficient, or is it about measuring over a longer period of time? For a spot-check of the water quality, measuring one or more parameters is sufficient. For monitoring and signalling developments, it is necessary to measure for a longer period of time and to use various sensors, connected to a modem and data network.
The parameters temperature, pH (acidity), ORP (redox), dissolved oxygen (DO) and conductivity give you an idea of the basic ecological quality of water.
Temperature is an important factor for the growth of various organisms. It also affects the density of water and various other parameters, such as conductivity, pH, and dissolved oxygen. An increase in the temperature of the water results in the chemical reactions, such as those required for the production of nutrients, being accelerated. An increase in temperature thus means a greater risk of algae bloom, with all its consequences. In order to respond to this in time, it is important to measure the water temperature accurately.
The pH value of water indicates how acidic or alkaline the water is. The pH value determines, among other things, how easily substances (e.g. metals) are soluble in the water.
The redox potential (ORP) indicates how chemically oxidizing or reducing water is. This also determines which chemical reactions are likely to occur, which in turn influences the development of flora and fauna in the water. It is also a good indicator of the presence of industrial, oxidizing chemicals such as chlorine.
The amount of dissolved oxygen or DO (dissolved oxygen) indicates how much oxygen is available for organisms in the water. Different organisms have different oxygen requirements. Low oxygen levels mean potential fish kills.
Conductivity is the ability of water to conduct electricity. This conductivity depends on the number of ions in the water. When chemical salts dissolve, they add ions to the water. The more salts present in the water, the higher the conductivity. Changes in conductivity can indicate an increase in ions from a source of pollution, or a decrease in ions from freshwater inflows in the form of heavy rainfall or meltwater.
Finally, turbidity is an indicator of the presence of solid particles in the water. The more suspended matter the water contains, the cloudier it becomes. Turbid water allows little sunlight to pass through, which limits photosynthesis and therefore hinders the growth of phytoplankton and plants. And when aquatic plants are less able to produce oxygen, this can also result in fish kills.
Turbidity can have various causes. More floating particles in the water can be caused by heavy rainfall, for example, which causes turbulence in the water, or by dredging activities.
To detect and monitor algae growth, various parameters are useful to measure. The first is temperature. Warming of the water is an initial indication that algae growth can occur, which is why it is especially important to keep an eye on this in spring and summer. In addition, dissolved oxygen, chlorophyll-a and phycocyanin are important parameters to measure. Turbidity and PAR are also important indicators that provide insight into the amount of sunlight that can penetrate the water.
When a sewer overflow occurs, water from the sewer is discharged into the surface water, which negatively affects the water quality. To detect this, it is good to measure for substances that occur in sewage water. Parameters such as dissolved oxygen, conductivity, tryptophan and CDOM/FDOM indicate that there are faeces and organic substances in the water and that sewage has probably been discharged. Increased turbidity can also be an indicator. In addition, an increase in organic substances in the water can stimulate algae growth, so it is important to detect this in time.
Fish mortality has various causes, but is usually caused by excessively high water temperatures, too little oxygen in the water or pollution. That is why it is first of all important to monitor temperature and dissolved oxygen (DO). It’s also advisable to look at possible causes of the above problems, such as algae growth or sewer overflows.
A number of things come into play with climate change, including higher temperatures and more powerful sunlight. The effects of this can be measured as algae growth, CO2 and PAR, among other things. Surface water absorbs more CO2 when temperatures rise. This is related to PAR (Photosynthetic Active Radiation), or how much sunlight penetrates the water, because sunlight stimulates CO2 absorption via photosynthesis. An increase in CO2 leads to acidification of water. This acidification of surface water is important to measure as it has negative effects on aquatic life.
Depending on the type of pollution, various parameters are relevant. For general pollution investigation, concentrations of dissolved oxygen, nitrate, ammonium, bromide, chlorophyll-A and blue-green algae can be measured.
In the case of industrial pollution, oil is an important indication, which can point to a discharge into surface water from industry, by traffic, or for example a crashed tanker.
Agricultural pollution, or pollution of the water system as a result of both artificial and regular fertilizer, can be measured via conductivity, and bromide, a component of artificial fertilizer.
Royal Eijkelkamp provides solutions for every water challenge, from the Scuba water probe for multiparameter measurements to simple field meters. Contact our specialists for customized advice.
