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Nitrate (NO3-) is an ion with a central nitrogen atom surrounded by three oxygen atoms. Dissolvable in water, nitrate is an essential plant nutrient that is often applied to crops to aid growth. The environment’s sources of nitrate include wastewater treatment plant discharge, septic systems, manure areas, and runoff from crops and lawns.

How Do Nitrate Sensors Work?

Using UV LED technology, the nitrate sensor measures the concentration of dissolved nitrate as nitrogen in the water. The sensor measures concentration levels by nitrate dissolved in seawater by examining its absorption of ultraviolet (UV) light.

Why Is It Important to Measure Nitrate Levels?

In an ideal world, continuous data on nitrate levels would be collected. However, as nitrate concentration in groundwater can change slowly, regional councils and alike may only sample yearly. Nevertheless, measuring for increasing levels can be vital in assessing the effects of nitrate toxicity on fish and aquatic life, so it is important to measure such levels to protect water quality from immediate impacts.

Nitrate Sensors Water Monitor New Zealand Farming Water

Nitrate Levels

For drinking water in New Zealand, the short-term Maximum Acceptable Value (MAV) of nitrate in water is 50 milligrams per litre (mg/L) for nitrate, equivalent to 11.3 mg/L nitrate-nitrogen (nitrate-N).

If nitrate-N reaches a concentration of half the level of 11.3 mg/L, so 5.65 mg/L, additional water quality and nitrate concentration monitoring are required in the community water supply.

How Do Nitrates Affect Water Quality?

As nitrogen is an effective fertiliser and essential plant nutrient, it is often used in various industries. However, such use can cause increased concentration in water, further causing adverse environmental effects.

Excess nitrogen contributes to the rapid growth of aquatic weeds and algae in rivers, streams, lakes, estuaries and the ocean. Commonly, this results in plant or algal blooms. As a result, plants die, and excess organic material decomposes, as dissolved oxygen in the surrounding water is used up and threatens aquatic life.

Fresh Water

What Are Signs of High Nitrate Levels?

Nitrogen itself can become toxic to aquatic life at high concentrations, specifically under certain water temperatures and pH conditions, causing direct harm to humans, fish and other organisms. Likewise, the nitrate form of nitrogen in drinking water can be toxic to humans and animals at high concentrations.

For humans, consuming water with high nitrate concentrations can cause physical effects. Signs of high Nitrate levels in drinking water include humans experiencing increased heart rate, nausea, headaches, and abdominal cramps.

For aquatic life, excessive growth of plants and algae will indicate high nitrate levels. This can also be shown through high chlorophyll levels. Reduced growth of fish and other aquatic organisms can indicate high nitrate levels, eventually stressing the fish and potentially death.

Impacts of High Nitrate Concentrations in Water

Human Health

Increase heart rate, nausea, headaches, and abdominal cramps.

Aquatic Life

Stressed organisms, reduced growth and production rate, and species deaths.

Human Health

Increase heart rate, nausea, headaches, and abdominal cramps.

Monitoring Nitrate to Indicate Water Quality

High water quality means the water is safe for using and drinking and helps support aquatic life and habitats. Monitoring nitrate levels indicate water quality as if levels rise, water can become unsafe and can be a sign of pollution and degradation.

New Zealand Environmental Water Quality Monitoring with Real Time Io T Artificial Intelligence Water Monitor RW

Nitrates and Water Quality Monitoring Updates

The RiverWatch blog is the data centre for New Zealanders committed to monitoring and enhancing our waterways. Learn more about the water quality of New Zealand and our integral connection with the waters, and stay up to date with important news, research and developments.