The deposition of sulphur in the rainwater in Northern Nigeria

The concentrations and amounts of SO₄-S were measured at eleven sites, situated between 350 and 880 kilometres from the sea, during two rainy seasons in Northern Nigeria. In both years, concentration showed a similar pattern at each site, being greatest at the beginning and end and smallest at the peak of the rains. The presence of anthropogenic atmospheric-S at the start of the rains, and of harmattan dust and lower precipitation at the beginning and end of the rains account for the concentration pattern observed. Amounts of S deposited ranged from 0.49–1.89, mean 1.14 kg S/ha. An estimate of dry deposition of S was made from the intercept on the y axis of a plot of amount deposited against rainfall. The dry deposition rates were 0.26 and 0.43 × 10^-12 g S/cm²/s respectively. The agricultural importance of the deposition is briefly discussed.