DRY DEPOSITION OF SULFUR ON THE MPUMALANGA HIGHVELD - A PILOT-STUDY USING THE INFERENTIAL METHOD

A pilot study which uses the inferential method to estimate dry deposi tion of sulphur on the central Mpumalanga highveld is discussed in thi s paper. Ambient concentrations of sulphur dioxide, particulates and m icro-meteorological measurements from 2 two-week field experiments, on e in winter and the other in summer are used as input to the NOAA/ATDD inferential model. The majority of dry deposited sulphur; 80% and 82% in winter and summer respectively, comes from SO2 during the daytime. Smaller contributions come from SO2 at night and from particulates du ring the day in both seasons. The contribution to the total dry deposi tion sulphur load by particulates at night appears to be negligible. A ssuming that sulphur precipitation for the two monitoring periods repr esents a full year then a dry deposition rate of 8.22 kg S ha(-1) yr(- 1), which exceeds the wet deposition rate of 5.7 kg S ha(-1) yr(-1), i s recorded for the central Mpumalanga highveld.