Chemical characterization and mapping of connection zones between urban wastewater and the Ebrié Lagoon (Abidjan, Ivory Coast, West Africa)

The aim of this work is to map the connection zones between the Ebrié lagoon and domestic wastewater and stormwater effluents, while specifying their pollution loads in Metallic Trace Elements (MTEs).To this end, four field campaigns were carried out to identify these connection zones and sample the water reaching the lagoon.The MTE content of the water sampled was determined by spectrometry (SAAF and ICP-MS).The results show that effluents from these areas are characterized by a generally neutral pH (6.5 to 8.3) and high electrical conductivity (0.087 to 38.1 mS/cm).Metallic fillers in domestic wastewater and rainwater reaching the lagoon vary from site to site and from season to season.The most abundant MTEs in the water are lead (560.0 ± 65.5 ppb in the dry season and 331.0 ± 13.8 ppb in the rainy season) and nickel (420.0 ± 103.6 ppb in the dry season and 288.0 ± 9.03 ppb in the rainy season), results which are an order of magnitude higher than the standards recommended by the World Health Organization , whose limit values are 10 ppb for lead and 20 ppb for nickel.