Dry Deposition Monitoring in Europe

Between 1993 and 1999 two EU funded projects wereexecuted aimed at (i) the development of drydeposition monitoring methods for core sites andlarge scale application, (ii) the installation andrunning of three core sites in Europe and (iii) the improvement and validation of models used forregional application. This article provides anoverview of the development of depositionmonitoring stations and the main results of thethree core sites, which were operated between1995 and 1998. Furthermore, the results of thedevelopment of a low cost monitoring system arepresented. Continuous measurements were made ofboth wet and dry deposition of sulphur andnitrogen components and base cations. The 4 yearsof data show a decrease in sulphur loads and notrend for the other components. It is shown thatthe surface affinities for sulphur depositionalso changed during the years, underpinning theneed for dry deposition monitoring. A conditionaltime average gradient system was successfullydeveloped and tested and provides a good meansfor low cost monitoring of dry deposition fluxes.The costs can be reduced by a factor of 3–4 without losing the accuracy of the annual average gas fluxes.