title: Persistent Hg contamination and occurrence of Hg-methylating transcript (hgcA) downstream of a chlor-alkali plant in the Olt River (Romania).
abstract: Chlor-alkali plants using mercury (Hg) cell technology are acute point sources of Hg pollution in the aquatic environment. While there have been recent efforts to reduce the use of Hg cells, some of the emitted Hg can be transformed to neurotoxic methylmercury (MeHg). Here, we aimed (i) to study the dispersion of Hg in four reservoirs located downstream of a chlor-alkali plant along the Olt River (Romania) and (ii) to track the activity of bacterial functional genes involved in Hg methylation. Total Hg (THg) concentrations in water and sediments decreased successively from the initial reservoir to downstream reservoirs. Suspended fine size particles and seston appeared to be responsible for the transport of THg into downstream reservoirs, while macrophytes reflected the local bioavailability of Hg. The concentration and proportion of MeHg were correlated with THg, but were not correlated with bacterial activity in sediments, while the abundance of hgcA transcript correlated with organic matter and Cl(-) concentration, indicating the importance of Hg bioavailability in sediments for Hg methylation. Our data clearly highlights the importance of considering Hg contamination as a legacy pollutant since there is a high risk of continued Hg accumulation in food webs long after Hg-cell phase out.
authors.affiliation: Limnology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 75236, Uppsala, Sweden.
authors.forename: Andrea G
authors.initials: AG
authors.lastname: Bravo
authors.affiliation: Institute F.-A. Forel, Earth and Environmental Sciences, University of Geneva, 10, Route de Suisse, 1290, Versoix, Switzerland.
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Loizeau
authors.affiliation: Institute F.-A. Forel, Earth and Environmental Sciences, University of Geneva, 10, Route de Suisse, 1290, Versoix, Switzerland.
authors.forename: Perrine
authors.initials: P
authors.lastname: Dranguet
authors.affiliation: Institute F.-A. Forel, Earth and Environmental Sciences, University of Geneva, 10, Route de Suisse, 1290, Versoix, Switzerland.
authors.forename: Stamatina
authors.initials: S
authors.lastname: Makri
authors.affiliation: Department of Chemistry, Umeå University, SE-90187, Umeå, Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Björn
authors.affiliation: Faculty of Geology and Geophysics, University of Bucharest, Bucharest, Romania.|GeoEcoMar, National Research and Development Institute for Marine Geology and Geoecology, Bucharest, Romania.
authors.forename: Viorel Gh
authors.initials: VG
authors.lastname: Ungureanu
authors.affiliation: Institute F.-A. Forel, Earth and Environmental Sciences, University of Geneva, 10, Route de Suisse, 1290, Versoix, Switzerland.
authors.forename: Vera I
authors.initials: VI
authors.lastname: Slaveykova
authors.affiliation: Institute F.-A. Forel, Earth and Environmental Sciences, University of Geneva, 10, Route de Suisse, 1290, Versoix, Switzerland. Claudia.Cosio@unige.ch.
authors.forename: Claudia
authors.initials: C
authors.lastname: Cosio
mesh_terms: D004784:Environmental Monitoring; D007220:Industrial Waste; D008628:Mercury / Q000032:analysis*; D045483:Rivers / Q000737:chemistry*; D012383:Romania; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D007220:Industrial Waste; D014874:Water Pollutants, Chemical; D008628:Mercury
keywords: Bacterial activity; Biota; Dispersion; Methylmercury; Reservoir; Sediments; Water