Nitrogen (nitrate and ammonium) is an important nutrient for plants living in aquatic ecosystems. Its sources can be wastewater treatment plants, runoff from cities, agricultural lands and farms, but it can also originate from the decomposition of organic matter, or manure leaching. Nitrate is water soluble, and the amount that is not used up can infiltrate into the soil and underlying aquifers, causing potential contamination.
Nitrate therefore, is an essential nutrient on the one hand, and also a potential water polutant that influences the living conditions of plants and animals and also the use of water. Too much nitrate may lead to eutrophication that in turn may cause oxygen deficiency.
Inorganic nitrogen in water is present primarily as ammonium, which per se is not harmful to living organisms (e.g., to fish). Under alkaline conditions, however, ammonia is formed that in turn is toxic.
It is important for aquatic ecosystems therefore, to simultaneously monitor the presence of both nitrate and ammonium in the water along with pH in order to calculate the concentration of ammonia. Ideally, this can be performed continuously including online data transmission allowing for immediate actions to be taken.
Measuring nitrate and ammonium/ammonia
The multi-parameter water quality measuring probes manufactured by Aquaread can be fitted with both nitrate and/or ammonium electrodes, which along with the standard parameters (pH, EC, ORP, DO, etc.) measured by the probe, are auxiliary sensors. All these parameters are measured simultaneously. Both electrodes (nitrate and ammonium) are ion-selective (ISE), so the concentration of the compound in the water is determined as the potential difference caused by the ionic activity. If the probe is used as a portable instrument, this potential difference is converted into mg/l concentration by the GPS Aquameter. Alternatively, if the probe is deployed as a long term monitoring device as part of an online monitoring system, the results are displayed by a web based interface. The nitrate electrode has a measuring range of 0 - 30 000 mg/l with an accuracy of ¬Ī10% or 2 mg/l. The ammonium sensor's measuring range is 0 - 9 000 mg/l and it has the same accuracy. Both electrodes can be used with the AP-2000, AP-5000, and AP-7000 Aquaprobes as well as with the AP-800 probe.
AP-2000 and AP-5000 are portable and ideal for taking point measurements at multiple measurement sites, while the AP-7000 features a self-cleaning system that allows it to be permanently deployed as a long term measurement device.
Aquaread's water quality monitoring equipment
Aquaread's highly accurate multi-parameter water quality testing sondes are designed to be used in the field. Yoy may chose from devices that are suitable for both fixed and spot monitoring. The AP-7000 is ideal for long term deployment with its self cleaning facility and 6 additional ports for ultimate user customisation. On the other end of the scale is the AP-LITE which is for when you don‚Äôt need multiple parameters. This portable probe takes just one optical sensor and is perfect for simply monitoring chlorophyll.