title: Physicochemical factors affecting the spatial variance of monomethylmercury in artificial reservoirs.
abstract: The aim of this study was to identify how hydrologic factors (e.g., rainfall, maximum depth, reservoir and catchment area, and water residence time) and water chemistry factors (e.g., conductivity, pH, suspended particulate matter, chlorophyll-a, dissolved organic carbon, and sulfate) interact to affect the spatial variance in monomethylmercury (MMHg) concentration in nine artificial reservoirs. We hypothesized that the MMHg concentration of reservoir water would be higher in eutrophic than in oligotrophic reservoirs because increased dissolved organic matter and sulfate in eutrophic reservoirs can promote in situ production of MMHg. Multiple tools, including Pearson correlation, a self-organizing map, and principal component analysis, were applied in the statistical modeling of Hg species. The results showed that rainfall amount and hydraulic residence time best explained the variance of dissolved Hg and dissolved MMHg in reservoir water. High precipitation events and residence time may mobilize Hg and MMHg in the catchment and reservoir sediment, respectively. On the contrary, algal biomass was a key predictor of the variance of the percentage fraction of unfiltered MMHg over unfiltered Hg (%MMHg). The creation of suboxic conditions and the supply of sulfate subsequent to the algal decomposition seemed to support enhanced %MMHg in the bloom reservoirs. Thus, the nutrient supply should be carefully managed to limit increases in the %MMHg/Hg of temperate reservoirs.
authors.affiliation: School of Environmental Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea.
authors.forename: Seam
authors.initials: S
authors.lastname: Noh
authors.affiliation: Institute of Environmental Protection and Safety, NeoEnBiz Co., Bucheon, Republic of Korea.
authors.forename: Chan-Kook
authors.initials: CK
authors.lastname: Kim
authors.affiliation: Institute of Environmental Protection and Safety, NeoEnBiz Co., Bucheon, Republic of Korea.
authors.forename: Jong-Hyeon
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Division of Chemical Research, National Institute of Environmental Research (NIER), Incheon, Republic of Korea.
authors.forename: Younghee
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Division of Chemical Research, National Institute of Environmental Research (NIER), Incheon, Republic of Korea.
authors.forename: Kyunghee
authors.initials: K
authors.lastname: Choi
authors.affiliation: School of Environmental Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea. Electronic address: shan@gist.ac.kr.
authors.forename: Seunghee
authors.initials: S
authors.lastname: Han
mesh_terms: D002734:Chlorophyll; D000077194:Chlorophyll A; D004784:Environmental Monitoring; D005618:Fresh Water / Q000737:chemistry; D019015:Geologic Sediments / Q000737:chemistry; D008628:Mercury / Q000032:analysis; D008767:Methylmercury Compounds / Q000032:analysis*; D052638:Particulate Matter; D013431:Sulfates / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D008767:Methylmercury Compounds; D052638:Particulate Matter; D013431:Sulfates; D014874:Water Pollutants, Chemical; D002734:Chlorophyll; D008628:Mercury; D000077194:Chlorophyll A
keywords: Eutrophic; Mercury; Monomethylmercury; Reservoir; Sulfate