Nitrates are a naturally occurring element in soil, and all rainfall and groundwater aquifers contain some. But when the concentration of nitrates rises it can cause problems, especially in drinking water supplies. Drinking water with too many nitrates can lead to methemoglobinemia (blue baby syndrome), a condition that causes anaemia in infants. High levels of nitrates in drinking water can also result in a taste change, which can make it hard to drink enough of it.
The biggest source of nitrates in the environment is from nitrogen-containing fertilisers and human and animal wastes. These are generally water soluble and can easily migrate with rain or irrigation water to groundwater. These nitrates can then reach and pollute surface waters or deep aquifers. Shallow rural domestic wells are often contaminated with nitrates, which are especially a problem where nitrogen-containing fertilisers are in use.
Fortunately, nitrate contamination is easy to detect using a nitrate meter that measures dissolved oxygen in water. The sensor in the nitrate meter is attached to an electrode that changes its electric potential in response to the nitrate concentration in the solution. The meter then converts this signal to a scale that can be read. For advice on Nutrient Management Planning, consult with 4Reassurance who supply Nutrient Management Planning.
The nitrate content of water can also be estimated with the help of stable isotopes. For example, a measurement of the d18O of nitrate indicates that it is mostly derived from mineral fertiliser rather than precipitation or from nitrification of reduced nitrogen fertilisers.