Ammonia
Why is it useful to measure ammonia?
Ammonia is a gas that contains nitrogen. In the ambient air, the emission of ammonia is therefore partly responsible for nitrogen deposition. This causes certain plant species to proliferate, and other species to disappear. If the plant composition within an ecosystem changes, this affects the insects and animals that live there. Less diversity or a lower species richness ensure that nature is less resilient.
In addition, chemical reactions of ammonia with nitrogen dioxide or sulphur dioxide will form secondary particulate matter. Particulate matter is harmful to our health.
Measurement method
You can measure ammonia yourself using passive samplers . These work on the principle of diffusion.
The blue tubes are passive samplers for measuring ammonia. They consist of a casing, with a rod coated with an acidic substance. The casing is blue and the rod is white. The air passes through the casing and the ammonia gas that we want to measure will adsorb in the coating of the white rod. After exposure to the air for a certain period, the sampler is analyzed in a laboratory. This is done, for example, by spectrophotometry or ion chromatography.
The samplers are protected from rain by a casing that does not obstruct airflow. The opening is oriented to the northeast to avoid rain ingress.
This video shows how to remove and hang the sampler.
Which passive sampler do you choose?
The passive sampler of the radial type is widely used for ammonia. Other types of samplers (e.g. badge type) are also usable. Studies show that the different types of samplers produce comparable results. Reliability is further increased by hanging at least 2 samplers next to each other.
What is the impact of eutrophication?
Ammonia, together with nitrogen oxides, contributes to the total amount of nitrogen in the air. Nitrogen is deposited on the soil, water and vegetation, causing acidification and eutrophication. This reduces soil and water quality, disrupts ecosystems and causes species to disappear. Eutrophication and acidification cause biodiversity to decline. See also the infographic from the VMM on the effects of air pollution on ecosystems.
Start measuring!
Make sure you have contacts with a company or laboratory for the delivery of the ammonia samplers, and also for the refrigerated return after the sample has been taken. Install suitable housing at the locations where you want to measure. Think of line or point sources that require a different location of the measurement locations. Also provide a background measurement point where there is no local ammonia emission.
- Investigate your environment and estimate where the major sources of ammonia are. Think of stables, manure storage, but also industry and traffic;
- Fermentation is also a source of ammonia, so be careful not to hang the sampler above or next to a green waste bin, a sewer drain or a pile of mown grass;
- Sweat also contains ammonia, so take this into account and always wear gloves when hanging up or taking down the samplers;
- Hang the sampler at a height of one and a half to two meters;
- Hang two to three samplers next to each other;
- Work with fixed measurement periods, for example bi-weekly or monthly;
- Keep a logbook in which you can record the periods with dates, weather conditions such as temperature, wind direction and precipitation and any events that may be of interest.
Interpret your results
The analysis results from the laboratory still need to be converted from the amount on the sampler to the concentration in the air. Then compare the analysis results from the laboratory with the data from your logbook to make correct interpretations. You now have an idea of the ammonia concentration in the ambient air. You cannot yet conclude how much ammonia comes from a specific source. You can, however, compare with measurements on the VMM website .
What is the impact of secondary particulate matter?
Some of the ammonia in the air precipitates, but it also reacts with other gases such as nitrogen dioxide or sulphur dioxide. The secondary fine dust that is formed in this process moves over long distances and is harmful to our health. This is shown in the infographic below from the RIVM (see also theinfographic VMM regarding fine dust).
