title: Effects of coastal managed retreat on mercury biogeochemistry.
abstract: We investigated the impact of managed retreat on mercury (Hg) biogeochemistry at a site subject to diffuse contamination with Hg. We collected sediment cores from an area of land behind a dyke one year before and one year after it was intentionally breached. These sediments were compared to those of an adjacent mudflat and a salt marsh. The concentration of total mercury (THg) in the sediment doubled after the dyke was breached due to the deposition of fresh sediment that had a smaller particle size, and higher pH. The concentration of methylmercury (MeHg) was 27% lower in the sediments after the dyke was breached. We conclude that coastal flooding during managed retreat of coastal flood defences at this site has not increased the risk of Hg methylation or bioavailability during the first year. As the sediment becomes vegetated, increased activity of Hg-methylating bacteria may accelerate Hg-methylation rate.
authors.affiliation: Department of Earth & Environmental Science, K.C. Irving Environmental Science Center, Acadia University, Wolfville, NS, B4P 2R6, Canada. Electronic address: t.sizmur@reading.ac.uk.
authors.forename: Tom
authors.initials: T
authors.lastname: Sizmur
authors.affiliation: Department of Earth & Environmental Science, K.C. Irving Environmental Science Center, Acadia University, Wolfville, NS, B4P 2R6, Canada.
authors.forename: Adam
authors.initials: A
authors.lastname: Godfrey
authors.affiliation: Department of Earth & Environmental Science, K.C. Irving Environmental Science Center, Acadia University, Wolfville, NS, B4P 2R6, Canada.
authors.forename: Nelson J
authors.initials: NJ
authors.lastname: O'Driscoll
mesh_terms: D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000032:analysis*; D008628:Mercury / Q000032:analysis*; D008767:Methylmercury Compounds / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical; D008628:Mercury
keywords: Biogeochemistry; Coastal; Mercury; Methylmercury; Sediment deposition