Dry Deposition of Sulphur at a High-Altitude Background Station in South Africa

Abstract

The inferential method is applied to estimate dry deposition rates of sulphur at a remote rural site on the South African south-eastern escarpment. Two 2-week intensive monitoring campaigns were conducted during the Ben MacDhui High Altitude Trace Gas and Transport Experiment (BHATTEX) when SO2, particulates and meteorological data were collected. Total sulphur deposition rates of 4.9 mg m−2 in summer exceeds the winter value of 3.0 mg m−2. The annual dry deposition rate for sulphur at the remote site of 1.1 kg ha−1 is about 13% of that occurring in the main source region, approximately 1000 km away along the most frequent transport pathway. Deposition of total sulphur on the south-eastern escarpment is a consequence of this large-scale regional transport of aerosols and trace gases over southern Africa.