Physical and chemical parameters and trace metal concentrations in the Ebrie Lagoon (Côte d'Ivoire): Influence of tides and urban wastewaters [Paramètres physiques et chimiques et métaux lourds des eaux de la Lagune Ebrié (Côte d'Ivoire): Influence de la marée et des effluents liquides urbaines]

The impact of urban wastewaters on total metal concentrations in the ebrié lagoon (côte d'ivoire) is unknown. physical and chemical parameters (temperature,conductivity,dissolved oxygen,salinity,ph,and redox hydrogen potential) and total metal concentrations (fe,cu,cd,pb,cr,and zn) were measured in water samples from cocody bay and wastewater effluents from 5:00 am to 10:00 pm in december 2008. dissolved oxygen concentrations at 0.5 m depth in the lagoon were below 2.7 mg/lfrom 5:00 am to3:00 pm over two consecutive days. this may explain in part the massive fish mortalities which occur between late november and january each year in the ebrié lagoon. physical and chemical parameters and metal concentrations in the lagoon were highest during high tides,except for zn and redox hydrogen potential. total metal concentrations (μg/l) in water ranged from 5 to 172 for fe,79 to 91 for cu,30 to 47 for cd,0 to 96 for pb,5 to 132 for cr,and 36 to 376 for zn. the wastewater / lagoon water concentration ratios were 20.86-37.82 for fe,1.53-6.3for zn,0.8-1.7 for cu,0.5-2.6 for cd,and 0.5-2 for cr,which indicate that wastewaters are significant sources of metals in the urban area of the ebrié lagoon. cd and cr concentrations in cocody bay exceeded the limits of the french and who standards for surface waters. total metal concentrations in wastewaters exceeded the us epa standards in general. wastewaters should be threated before being discharged in the ebrié lagoon.