Stolk AP, Noordijk H, den Hollander HA, van Zanten MC, Wichink Kruit RJ, van Pul WAJ
RIVM Report 2016-0136
Ammonia concentrations measured in air show a slight increase over the period 2005-2014. Averaged across the Netherlands, the increase was about 1.5 percent per year. The largest increase was observed in the northern and eastern parts of the country. This can be concluded from a RIVM report which describes the trend in the concentrations of ammonia in the period 2005-2014.
For this report, measurements of both the Measuring Ammonia in Nature Network (MAN) and the National Air Quality Monitoring Network (LML) were used. Since 2005, the MAN network provides monthly average ammonia concentrations in Dutch Natura2000 areas. These ammonia measurements are carried out because these areas are sensitive to an increase in the nitrogen level, which can result in a decrease in biodiversity. The MAN network was set up because nature areas were hardly covered by the LML network. Both networks show increasing ammonia concentrations in the observed period.
Agricultural ammonia emissions largely determine the ammonia concentration in air. Weather conditions and the chemical composition of the atmosphere will also affect this concentration.
At a national level, ammonia emissions (reported on http://www.emissieregistratie.nl) show a decline over the period 2005- 2013. This decline is not observed in the ammonia concentration in air as measured by the MAN and LML networks, even after correcting for changes in weather conditions and chemical composition of the atmosphere. The cause for this difference between trends in ammonia emissions and concentrations is the focus of future study.