title: Mercury methylation in high and low-sulphate impacted wetland ponds within the prairie pothole region of North America.
abstract: Using enriched stable (201)Hg injections into intact sediment cores, we provide the first reported Hg methylation potential rate constants (km) in prairie wetland ponds (0.016-0.17 d(-1)). Our km values were similar to other freshwater wetlands and did not differ in ponds categorized with high compared to low surface water concentrations of sulphate. Sites with high sulphate had higher proportions of methylmercury (MeHg) in sediment (2.9 ± 1.6% vs. 1.0 ± 0.3%) and higher surface water MeHg concentrations (1.96 ± 1.90 ng L(-1)vs. 0.56 ± 0.55 ng L(-1)). Sediment-porewater partitioning coefficients were small, and likely due to high ionic activity. Our work suggests while km measurements are useful for understanding mercury cycling processes, they are less important than surface water MeHg concentrations for assessing MeHg risks to biota. Significant differences in MeHg concentrations between sites with high and low sulphate concentrations may also inform management decisions concerning wetland remediation and creation.
authors.affiliation: Department of Biology, University of Regina, 3737 Wascana Parkway, Regina, SK S4S 0A2, Canada.
authors.forename: Cameron G J
authors.initials: CG
authors.lastname: Hoggarth
authors.affiliation: Department of Biology, University of Regina, 3737 Wascana Parkway, Regina, SK S4S 0A2, Canada. Electronic address: britt.hall@uregina.ca.
authors.forename: Britt D
authors.initials: BD
authors.lastname: Hall
authors.affiliation: Department of Physical and Environmental Science, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4, Canada.
authors.forename: Carl P J
authors.initials: CP
authors.lastname: Mitchell
mesh_terms: D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000737:chemistry*; D008629:Mercury Isotopes / Q000032:analysis; D008745:Methylation; D008767:Methylmercury Compounds / Q000032:analysis*; D061005:Ponds / Q000032:analysis; D012525:Saskatchewan; D013431:Sulfates / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D053833:Wetlands
chemical_list: D008629:Mercury Isotopes; D008767:Methylmercury Compounds; D013431:Sulfates; D014874:Water Pollutants, Chemical
keywords: Methylmercury; North American Great Plains; Sediment; Sulphate; Surface water; Wetland ponds