Atmospheric bulk deposition of mercury in Denmark

Atmospheric bulk deposition of mercury has been measured in 1990/91 at 7 localities in Denmark at four coastal stations and three forest stations. At five localities duplicate samplers were set up to study the reproducibility of the samplers. At the localities with duplicate samplers one sample was analyzed by the Danish laboratory (FORCE Institutes) by radiochemical neutron activation analysis (RNAA) and by the Swedish Environmental Research Institute (IVL) with application of plasma emission spectrometry (AES) or atomic fluorescence spectrometry (AFS). The results showed no significant difference between the results of RNAA and AES at the 97.5% probability level. No significant difference was found for the methods RNAA and AFS. The reproducibility of the new samplers which were constructed by IVL for collection of precipitation and measurement of bulk deposition of mercury were excellent with no significant difference between the two parameters for the duplicate samplers. The yearly atmospheric bulk deposition rate of mercury was nearly identical at three of the coastal stations, between 7.4 - 9.2 μg/m2,yr, and with higher values for the forest stations, 10.5 - 13.1 μg/m2,yr. One coastal station had a higher depostion of 14.8 μg/m2,yr which is in agreement with earlier findings based on a small number of precipitations events. Much lower values are found in this study in comparison with a Danish study from 1976/78 where 40 - 65 μg/m2,yr were found. It is not possible to decide whether this difference is caused by reductions in inputs and/or different sampling techniques. (au)