AssessmentoftheTemporalandSpatialVariationoftheMercury ContentofLakeNokou´ einSouthernBeninRepublic(WestAfrica)

Abstract

Anthropogenic input of mercury into watersheds is becoming increasingly noticeable and is the cause of fishery products contamination.ThishadledtotheConventionofMinamatasignedandratifiedbythevastmajorityofthecountriesintheworld. Lake Nokou´e in Benin Republic, the most fishery products provider in West Africa, is subject to mercury pollution. The health threattoboththebenthicandtheconsumersofthefisheryproductsfromthislakehastobeanticipatedbypreciselydetermining the dynamics of mercury contamination of the waters and sediments of Lake Nokou´e, taking into account the anthropogenic contribution.Waterandsedimentsampleswerecollectedon23sitestwiceamonthforfoursamplingcampaigns.Parameterssuch as pH, salinity, COD, and SS are evaluated in the water. The assessment of total mercury is conducted by cold vapor atomic absorptionaccordingtotheUSEPA7473method,usingadirectmercuryanalyzer(DMA-80).Onaverage,themercurycontentin LakeNokou´ewateris0.43±0.57μg/kg.Itsvariationislinkednotonlytotheseasonalvariationbutalsotothatofthesuspended matter. South of the lake, the sediments are extremely polluted (5≤Igeo) and present a risk of frequent effects for the benthic species present