The atmosphere, aerosols, trace gases and biogeochemical change in southern Africa: a regional integration

Attention is focused on temperature and rainfall changes occurring over the subcontinent of southern Africa, on atmospheric circulation and transport of aerosols and trace gases in the vertical and horizontal, and on repeated recirculation of atmospheric constituents over the region. It is shown tha t most air, and whatever is contained therein, exits the subcontinental air space in a major plume moving to the east over the Indian Ocean at 31 degre esS towards Australia and New Zealand. On occasions, the plume may be disce rnible over Australasia. Some of the consequences of sulphur emission and t ransport of sulphate aerosols over the region are considered and it is show n that on occasions sulphates from South Africa may be observed in Kenya an d beyond. The possible role of aerosols in diminishing and enhancing region al rainfall is examined. The contribution of atmospheric particulates in th e biogeochemical cycling of nutrients in terrestrial and marine ecosystems is illustrated by showing that airborne nitrates and phosphates contribute significantly to the balancing of the papyrus nutrient budget in the Botswa na wetland ecosystem of the Okavango Delta region. Future climate scenarios also are considered. It is concluded that changing regional climate is one of the major driving forces leading to biogeochemical changes in terrestri al and marine ecosystems sustaining the region.