Acid rain in the tropical forests of the Ivory Coast

Abstract This paper presents the first results concerning the acidity of the precipitation collected over a period of 1 year (February 1983–March 1984) in an undisturbed area of tropical forest in the Ivory Coast. A large proportion of the precipitation is acid, 77% bas a pH below 5.6. The average acidity is 5.0, with a temporal evolution tending towards a basic pH during the dry season, characteristic of the influence of the Sahelian terrigenous dust source and tending towards an acid pH of about 4.2 at the beginning of each humid period. This result, new for an African tropical forest, confirms the observations made in the Amazonian forests or in those of Northern Australia. An extensive research program on the acidity in the equatorial areas was started in the forests of the Ivory Coast and Congo in order to confirm this preliminary study.