title: Evidence of methylmercury production and modification of the microbial community structure in estuary sediments contaminated with wastewater treatment plant effluents.
abstract: The Seine's estuary (France) waters are the receptacle of effluents originating from wastewater treatment plants (WWTP). In this estuary, mudflats are deposition zones for sediments and their associated contaminants, and play an essential role in the mercury (Hg) biogeochemical cycle mainly due to indigenous microorganisms. Microcosms were used to assess the impact of WWTP-effluents on mercury methylation by monitoring Hg species (total dissolved Hg in porewater, methylmercury and total mercury) and on microbial communities in sediments. After effluent amendment, methylmercury (MeHg) concentrations increased in relation with the total Hg and organic matter content of the WWTP-effluents. A correlation was observed between MeHg and acid-volatile-sulfides concentrations. Quantification of sulfate-reducing microorganisms involved in Hg methylation showed no increase of their abundance but their activity was probably enhanced by the organic matter supplied with the effluents. WWTP-effluent spiking modified the bacterial community fingerprint, mainly influenced by Hg contamination and the organic matter amendment.
authors.affiliation: Institute for Microbial Biotechnology and Metagenomics, Department of Biotechnology, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa. jramond@uwc.ac.za
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Ramond
authors.forename: Fabienne
authors.initials: F
authors.lastname: Petit
authors.forename: Laurent
authors.initials: L
authors.lastname: Quillet
authors.forename: Baghdad
authors.initials: B
authors.lastname: Ouddane
authors.forename: Thierry
authors.initials: T
authors.lastname: Berthe
mesh_terms: D004784:Environmental Monitoring; D005618:Fresh Water / Q000737:chemistry / Q000382:microbiology; D019015:Geologic Sediments / Q000737:chemistry* / Q000382:microbiology; D008767:Methylmercury Compounds / Q000032:analysis* / Q000378:metabolism; D059013:Microbial Consortia; D012623:Seawater / Q000737:chemistry / Q000382:microbiology; D016999:Sulfur-Reducing Bacteria / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000378:metabolism
chemical_list: D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical