The Chemical Characteristics of Rainwater and Wet Atmospheric Deposition Fluxes at Two Urban Sites and One Rural Site in Côte d’Ivoire
Mohamed L. Kassamba-Diaby,
Corinne Galy-Lacaux,
Véronique Yoboué,
Jonathan E. Hickman,
Camille Mouchel-Vallon,
Kerneels Jaars,
Sylvain Gnamien,
Richmond Konan,
Eric Gardrat,
Siélé Silué
Affiliations
Mohamed L. Kassamba-Diaby
Laboratoire des Sciences de la Matière, de l’Environnement et de l’Énergie Solaire, Département de Physique, Unité de Formation et de Recherche en Sciences des Structures des Matières et de la Technologie, Université Félix Houphouët-Boigny, Abidjan BPV 34, Côte d’Ivoire
Corinne Galy-Lacaux
Laboratoire d’Aérologie, Université Toulouse III Paul Sabatier, CNRS, 14 Avenue Édouard Belin, 31400 Toulouse, France
Véronique Yoboué
Laboratoire des Sciences de la Matière, de l’Environnement et de l’Énergie Solaire, Département de Physique, Unité de Formation et de Recherche en Sciences des Structures des Matières et de la Technologie, Université Félix Houphouët-Boigny, Abidjan BPV 34, Côte d’Ivoire
Jonathan E. Hickman
Center for Climate Systems Research, Columbia University, 2880 Broadway, New York, NY 10025, USA
Camille Mouchel-Vallon
Laboratoire d’Aérologie, Université Toulouse III Paul Sabatier, CNRS, 14 Avenue Édouard Belin, 31400 Toulouse, France
Kerneels Jaars
Atmospheric Chemistry Research Group, North-West University, Potchefstroom, 11 Hoffman Street, Potchefstroom 2531, South Africa
Sylvain Gnamien
Laboratoire des Sciences de la Matière, de l’Environnement et de l’Énergie Solaire, Département de Physique, Unité de Formation et de Recherche en Sciences des Structures des Matières et de la Technologie, Université Félix Houphouët-Boigny, Abidjan BPV 34, Côte d’Ivoire
Richmond Konan
Laboratoire des Sciences de la Matière, de l’Environnement et de l’Énergie Solaire, Département de Physique, Unité de Formation et de Recherche en Sciences des Structures des Matières et de la Technologie, Université Félix Houphouët-Boigny, Abidjan BPV 34, Côte d’Ivoire
Eric Gardrat
Laboratoire d’Aérologie, Université Toulouse III Paul Sabatier, CNRS, 14 Avenue Édouard Belin, 31400 Toulouse, France
Siélé Silué
Département de Mathématiques, Physique et Chimie, University Peloforo Gbon Coulibaly, Korhogo P.O. Box 1328, Côte d’Ivoire
Due to their close relationship with atmospheric chemical composition and global impacts on ecosystems, it is of crucial importance to determine rain chemical composition and quantify wet deposition. In this study, we characterized the chemical composition of precipitation at one rural and two urban sites in Côte d’Ivoire along a south-north transect. Annual and monthly Volume Weighted Mean (VWM) concentration of major ions, as well as wet deposition fluxes in rainwater samples from Abidjan, Korhogo (urban sites), and Lamto (rural site), have been calculated. We also simulated air mass back-trajectories and generated satellite maps of burnt fraction and nitrogen species emissions (NH3, NO2) to better analyze our results. Results show that the dominant ion at both urban sites is Ca2+, whereas NH4+ dominates the chemical content of the Lamto rural site. The analysis of atmospheric sources of influence shows that urban sites rains are characterized by a mixture of terrigenous continental and anthropogenic sources (39–33%), as well as a high marine contribution (34–24%) and a significant nitrogenous contribution (18–25%) mainly associated to fossil fuel from road traffic, domestic and biomass burning sources. At the rural Lamto site, marine, terrigenous, and nitrogenous contributions represent, respectively, 14%, 25%, and 30%. The average pH values are, respectively, 5.76, 5.31, and 5.57 for Abidjan, Lamto, and Korhogo, with a preponderance of mineral acidity contribution at the urban sites, while the organic acidity contribution dominates in Lamto. Neutralization factor (NF) of mineral and organic acids calculations revealed that Ca2+ and NH4+ are the most important neutralizing ions in the rain at all three sites, and we estimated that 79% to 87% of the rain acidity is neutralized by alkaline compounds.