Ground based in situ observations of ammonium at Tustervatn (NO0015R) using bulk_sampler. These measurements are gathered as a part of the following projects EMEP, NILU and they are stored in the EBAS database (http://ebas.nilu.no/). Parameters measured are: ammonium in precip (mass_concentration_of_ammonium_in_precipitation), ammonium in precip (mass_concentration_of_ammonium_in_precipitation)