Ground based in situ observations of nickel at Ulborg (DK0031R) using filter_3pack. These measurements are gathered as a part of the following projects CAMP, EMEP and they are stored in the EBAS database (http://ebas.nilu.no/). Parameters measured are: nickel in aerosol (mass_concentration_of_nickel_in_dry_aerosol_particles_in _air)