Measurements of ammonia in ambient air and over a controlled artificial source during the AMICA field campaign at a rural site in the Ile-de-France region
Résumé
Ammonia is an atmospheric pollutant precursor of inorganic fine particles (sulphate and ammonium nitrate particles) that are particularly harmful to human health. Ammonia and particulate matter (PM) are responsible for severe pollution outbreaks over Europe (LCSQA, LCSQA 2019), during springtime of 2012 (Kutzner et al., 2021), 2014 (Fortems-Cheiney et al., 2016), 2015 (Petit et al., 2017), 2016 (Tournadre et al., 2020: Viatte et al., 2020) and 2020 (Viatte et al., 2021). Despite this major societal and scientific interest, there is a crucial lack of routine ammonia and aerosol speciation observations. One of the scientific reasons comes from the difficulty to measure atmospheric ammonia due to its sticky, volatile, and reactive nature (von Bobrutzki et al., 2010).The objective of the Multi-Instrumental Analysis of Ammonia Concentrations (AMICA) project is to compare the response of different available systems for measuring atmospheric ammonia at a rural site in the Île-de-France region. The 14 instruments based on different NH3 measurement techniques are compared over a wide range of ammonia concentrations from ambient atmospheric to boosted concentrations (10 to 600 ppbv) using an innovative 400 m2 ammonia emission system. They are all synchronized with a cross-correlation function based on the median value. At elevated concentrations all inlet-based instruments sampling to the same manifold performed very well on precision, even at high temporal resolution monitoring (1 min) that highlights a great progress for current in situ NH3 analysers. By comparing with the data from a mini Differential Optical Absorption Spectrometer (miniDOAS) and a sequential acid trap-IC (ROSAA), we demonstrated that inlet design perturbs the response time of the instruments connected to the manifold, which was already mentioned in literature. This measurement campaign is part of a series of ammonia projects that have recently taken place in France.