title: Total Mercury and Methylmercury Response in Water, Sediment, and Biota to Destratification of the Great Salt Lake, Utah, United States.
abstract: Measurements of chemical and physical parameters made before and after sealing of culverts in the railroad causeway spanning the Great Salt Lake in late 2013 documented dramatic alterations in the system in response to the elimination of flow between the Great Salt Lake's north and south arms. The flow of denser, more-saline water through the culverts from the north arm (Gunnison Bay) to the south arm (Gilbert Bay) previously drove the perennial stratification of the south arm and the existence of oxic shallow brine and anoxic deep brine layers. Closure of the causeway culverts occurred concurrently with a multiyear drought that resulted in a decrease in the lake elevation and a concomitant increase in top-down erosion of the upper surface of the deep brine layer by wind-forced mixing. The combination of these events resulted in the replacement of the formerly stratified water column in the south arm with one that was vertically homogeneous and oxic. Total mercury concentrations in the deep waters of the south arm decreased by approximately 81% and methylmercury concentrations in deep waters decreased by roughly 86% due to destratification. Methylmercury concentrations decreased by 77% in underlying surficial sediment, whereas there was no change observed in total mercury. The dramatic mercury loss from deep waters and methylmercury loss from underlying sediment in response to causeway sealing provides new understanding of the potential role of the deep brine layer in the accumulation and persistence of methylmercury in the Great Salt Lake. Additional mercury measurements in biota appear to contradict the previously implied connection between elevated methylmercury concentrations in the deep brine layer and elevated mercury in avian species reported prior to causeway sealing.
authors.affiliation: Department of Geology & Geophysics, University of Utah , Salt Lake City, Utah 84112, United States.
authors.forename: Carla
authors.initials: C
authors.lastname: Valdes
authors.affiliation: Department of Chemistry, Westminster College , Salt Lake City, Utah 84105, United States.
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Black
authors.affiliation: Division of Wildlife Resources, Utah Department of Natural Resources , Salt Lake City, Utah 84114, United States.
authors.forename: Blair
authors.initials: B
authors.lastname: Stringham
authors.affiliation: Department of Chemistry, Westminster College , Salt Lake City, Utah 84105, United States.
authors.forename: Jeffrey N
authors.initials: JN
authors.lastname: Collins
authors.affiliation: Department of Chemistry, Westminster College , Salt Lake City, Utah 84105, United States.
authors.forename: James R
authors.initials: JR
authors.lastname: Goodman
authors.affiliation: Department of Chemistry, Westminster College , Salt Lake City, Utah 84105, United States.
authors.forename: Heidi J
authors.initials: HJ
authors.lastname: Saxton
authors.affiliation: Department of Chemistry, Westminster College , Salt Lake City, Utah 84105, United States.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Mansfield
authors.affiliation: Department of Chemistry, Westminster College , Salt Lake City, Utah 84105, United States.
authors.forename: Joshua N
authors.initials: JN
authors.lastname: Schmidt
authors.affiliation: Department of Geology & Geophysics, University of Utah , Salt Lake City, Utah 84112, United States.
authors.forename: Shu
authors.initials: S
authors.lastname: Yang
authors.affiliation: Department of Geology & Geophysics, University of Utah , Salt Lake City, Utah 84112, United States.
authors.forename: William P
authors.identifier: http://orcid.org/0000-0003-3126-3877
authors.initials: WP
authors.lastname: Johnson
mesh_terms: D058448:Biota; D004784:Environmental Monitoring; D019015:Geologic Sediments; D060106:Lakes; D008628:Mercury; D008767:Methylmercury Compounds; D014589:Utah; D014867:Water; D014874:Water Pollutants, Chemical
chemical_list: D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical; D014867:Water; D008628:Mercury