Quantitative biomonitoring of nitrogen deposition with TONIS (Total N Input Biomonitoring System).

Monitoring of air pollutants is an important instrument to detect threats and to observe temporal trends of emissions. Determining the spatial distribution of oxidized and reduced N species via modelling requires sufficient knowledge about innumerous small sources from traffic, settlements and agriculture. Empirical studies are required to validate the model data but measurements of the total N deposition (e.g. micrometeorological measurements) are very expensive. Against this background, the TONIS, a new suitable technique which combines a biomonitoring with plants and technical measurements was developed. During 6 exposures between 2012 and 2016 at different polluted sites in Northwest Germany, TONIS accumulated between 17 and 25 kg N ha-1 yr(-1)t. The results are feasible compared to simultaneously measured NH3 and NO2 concentration and bulk N deposition. At one site within a peat bog the accumulated N in TONIS was found to be in the range of total N deposition derived from a micrometeorological approach.