Water Quality Monitoring Parameters
Multiparameter
RS Hydro provide a wide range of multiparameter water quality instruments, sensors and meters ranging from process analysers to single parameter sensors and multiparameter water quality sondes.
Ammonia / Ammonium
Ammonia is normally found in very low concentrations in natural waters. It is a result of microbiological activity breaking down nitrogen-containing material. Elevated levels of ammonia can be very harmful to aquatic life and fish in particular.
Blue Green Algae
Blue-green algae or cyanobacteria represent a group of organisms that can produce potent natural toxins. When excess nutrients are present the algae populations can explode causing large blooms. These can deplete oxygen levels and block light from reaching aquatic plants
BOD
Biological Oxygen Demand (BOD) provides an estimate of the oxygen uptake by microorganisms during the breakdown of organic material present in a water sample. It is usually measured in the laboratory under controlled conditions over a 5-day period (i.e. BOD5) and oxygen depletion compared to a control.
Bromide
Bromide is a Chemical compound commonly used as a tracer for the detection of fertilizers within the natural environment. In many cases bromide is used as an alternative to Chloride as there are less occurrences of bromide with the natural environment. Bromide is detected using a sensor called an ISE (ion selective electrode).
CDOM
Dissolved organic matter (DOM) is a mixture of soluble organic compounds and is an essential component of biochemical cycling. In aquatic systems it controls nutrient availability, UV light penetration, metal availability and transport, ecosystem productivity and can create disinfectant by-products during water treatment processes. CDOM, or Coloured Dissolved Organic Matter, represents a large proportion of the total DOM pool particularly terrestrially derived humic and fulvic acids.
Chloride
Almost all natural waters contain chloride ions; the concentration varies according to local mineral content of the underlying geology. Road salt used as de-icer can lead to elevated levels of chloride, which are harmful to aquatic life. High levels of chloride in drinking water can lead to an unpleasant briny taste.
Chlorine
Chlorine has a primary use within water treatment systems in particularly drinking water, swimming pools and many water treatment systems. The main role of chlorine is to kill off any micro organisms within the water. Chlorine is commonly measured as residual and total chlorine.
Chlorophyll
Chlorophyll is a green pigment found in almost all plants, algae, and cyanobacteria. High amounts of chlorophyll in a water body are an indicator of nutrient pollution, as excess nutrients fuel the growth of algae.
COD
Chemical Oxidation Demand (COD) is a test that measures the amount of oxygen required to chemically oxidize the organic material present in water. The most commonly adopted method involves the addition of potassium dichromate and concentrated sulphuric acid to the water sample with oxygen concentration measured before and after. Many governments impose strict regulations regarding the maximum COD that wastewater discharge can exhibit.
Conductivity
Conductivity is a measure of the ability of water to pass an electric current; it is affected by the presence of dissolved solids such as chloride, nitrate and phosphate. Conductivity can be a very useful indicator that a discharge of some sort has entered a stream, or some other change has occurred.
Crude Oil (Hydrocarbons)
Crude oil or petroleum is found in the natural environment as either oil in water or dissolved oil in water. Its chemical structure is primarily made up of 6-sided aromatic carbon rings. Due to crude oil being highly fluorescent, it can be easily detected using modern day fluorescent techniques.
Depth / Level
Depth of water or level is an important factor in water quality measurements as well as for hydrological monitoring. Depth can be used to help calculate flow volumes and thereby convert pollutant concentration values into environmental loads. It can also be used to define storm events and trigger automatic samplers.
Dissolved Oxygen
Oxygen is essential for the survival of aquatic life and is incorporated into surface waters by direct absorption from the atmosphere, more so in turbulent streams. It is then consumed by organisms and decaying organic matter. An excess of decaying organic matter leads to a shortage of oxygen, which can prove fatal for fish.
DOC
Dissolved organic carbon (DOC) is operationally defined as the total quantity of organic carbon compounds that pass through a 0.45µm filter, and represents the vast majority of organic material in most water samples. In aqueous systems DOC influences a range of geochemical processes by directly controlling pH levels. Furthermore, it influences water colour, the transport and degradation of pollutants, the depth of the photic zone and can cause the formation of disinfection by-products.
Fluorescein
Mainly used as a dye within the surface water and ground water sources for the detection of flow paths. Detection of flourescein is provided by a flourometer which utilises low detection limits so that small quantities can be used to avoid toxic affects to animal organisms.
Nitrate
Nitrate is a naturally occurring by-product of the breakdown of organic waste. In low concentrations it stimulates the growth of aquatic plants. At higher concentrations it can be directly harmful and can also lead to excess algae growth and eutrophication. The primary source of excess nitrate is surface runoff from agricultural land.
OBA (Optical Brightening Agents)
Optical Brightening Agents (OBAs) are a class of fluorophores that emit light in the blue range (415-445nm) and are commonly added to modern laundry detergents to compensate for discolouration of clothing with age. Due to mixing of grey - and wastewaters in most residential plumbing systems, OBAs can be detected in both septic tanks and sewage systems. Hence, measurement of OBA fluorescence can be used to track polluting organic matter sources.
ORP / Redox
Redox (Reduction-oxidation) or ORP (Oxidation Reduction Potential) is a measure of the oxidising or reducing potential of a water body. Many important biochemical processes are oxidation or reduction reactions (e.g. ammonia>nitrite>nitrate). The ORP level in a river or treatment plant will govern (along with DO and pH levels) which reactions are prevalent.
Orthophosphate
Orthophosphate is the most readily used form of phosphorous. Phosphorous occurs widely in plants, micro-organisms and animal wastes; it is also used as an agricultural fertiliser and is found in detergents. Surface run-off and sewage discharges are primary sources of phosphorous entering surface waters, where it can lead to eutrophication.
PAR (photosynthetic active radiation)
This is a portion of solar radiation that falls between 400 and 700 nanometers and is used by organisms for photosynthesis. Solar radiation in the water column is of interest for primary productivity studies and on land for calculation of evapotranspiration rates.
pH
pH is related to the concentration of hydrogen ions in a solution and is a measure of acidity or alkalinity. In natural ecosystems it can vary from around 4.5, for acid peaty upland waters, to over 10.0 where there is intense photosynthetic activity.
Phosphate
Phosphate (P) is a macronutrient essential for the survival and growth of organisms in aquatic systems . High concentrations of P are found in agricultural fertilizers, manure and organic wastes in sewage effluent. In freshwater P is generally considered the main ‘limiting nutrient’ and thus excessive inputs often leads to eutrophication. Therefore, the Water Framework Directive stipulates that P inputs, from both diffuse and point sources, need to be tightly controlled.
Refined Oil
Oil spills can be devastating to wildlife and damaging to water treatment processes. It is therefore important to detect oil and hydrocarbons as early as possible to avoid widespread harm. Monitoring for oil is usually confined to high risk areas, e.g. oil platforms, marinas and ports.
Rhodamine
Rhodamine is a red coloured dye frequently used as a tracer dye in water flow, transport and dilution studies. It is highly fluorescent and can therefore be detected in very low concentrations by appropriate instrumentation.
Salinity
Salinity is a parameter which refers to the level of dissolved salt within water. Salinity is crucial in many natural river courses and marine environments as it governs many of the key biological systems. Salinity is commonly calculated from a conductivity reading converted to salinity PSS (practical salinity scale) using a conversion factor.
Sodium
Sodium is one of the elements which forms the mineral Sodium Chloride, commonly referred to as salt. Its measurement is important within both the natural environment and process environment, though in drinking water production is where most observation occurs as the human intake of highly levels of sodium can have adverse health effects.
Temperature
Physical temperature of the watercourse. Largely dictated by climate, but also of interest around thermal discharges. Temperature extremes can be harmful to aquatic organisms, and also have an effect on other parameters, e.g. pH and dissolved oxygen.
TDS (Total Dissolved Solids)
Total dissolved solids (TDS) is a measure of the combined inorganic and organic substances dissolved in water. It is directly related to the electrical conductivity of water and as such can be used as an indication of change. Only relevant in freshwater systems as salinity will dramatically increase the conductivity and therefore apparent TDS.
Turbidity
Turbidity is a measure of the clarity of water. Silts and soils that are suspended within rivers and lakes cause high levels of turbidity, especially during storm and run-off events.
TDG (Total Dissolved Gas)
TDG is the combined measurement of total dissolved gases in water related to atmospheric pressure. The TDG measurement utilises a pressure sensor attached to a membrane. The sum of the partial pressures is then measured by the pressure sensors, then related to total dissolved gas.
Tryptophan
Tryptophan is an aromatic (relatively complex) amino acid that is fluorescent in the UV region (i.e. it absorbs and re-emits light of a certain wavelength). Recent work has shown that Tryptophan-like (T1) fluorescence peaks in surface waters are associated with the input of labile organic carbon (e.g. sewage or farm waste) and products of its microbial breakdown. Furthermore, the strong correlation between BOD5 and T1 fluorescence means BOD5 can be monitored in real time, in-situ using a T1 a submersible fluorometer.
Total Suspended Solids (TSS)
Total Suspended Solids (TSS) is the portion of fine particulate matter that remains in suspension in water. It measures a similar property to turbidity, but provides an actual weight of particulate matter for a given volume of sample (usually mg/l).
