Monitoring the dry deposition of SO2 in the Netherlands: Results for grassland and heather vegetation

Abstract

Abstract An automated system based on the micrometeorological gradient technique has been developed to measure the dry deposition of SO 2 on a routine basis. Measurements were made at two locations in the Netherlands. From these results dry deposition fluxes, dry deposition velocities and surface resistances for a heathland and for an agricultural grassland site were estimated using a selected set of data and a calculation procedure based on micrometeorological considerations. An extensive analysis was made to determine uncertainties in the resulting deposition parameters. From this analysis it has been concluded that the uncertainty in these parameters is almost completely determined by the random errors in measured concentrations. The meteorological surface exchange parameters can be estimated sufficiently accurately ( −1 were calculated for wet and dry conditions, respectively. At the heathland site, a similar distinct difference between R c values for wet and dry conditions was found. These values are 20(±21) and 70(±90) s m −1 , respectively. The yearly average dry deposition flux for SO 2 at the grassland site amounts to 585(±330) mol ha −1 yr −1 , while at the heathland site the yearly average flux was 300(±270) mol ha −1 yr −1 . The yearly average dry deposition velocity at 4 m height was 1.2(±0.3) cm s −1 at the grassland site and 0.8(±0.4) cm s −1 at the heathland site.