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Determining the Relative Importance of Water Column and Sediment Methylation Rates in the Nacimiento Reservoir, California
Citation:
Millard, G., C. Eckley, AND T. Luxton. Determining the Relative Importance of Water Column and Sediment Methylation Rates in the Nacimiento Reservoir, California. SETAC conference, N/A, N/A, December 09, 2020.
Impact/Purpose:
Mercury methylation often occurs at the active redox boundary between oxic and anoxic conditions in the sediment and the water column of lakes and reservoirs. Previous studies have suggested that the dominant zone of methylation shifts from the sediments into the water column during periods of stratification, however, studies simultaneously measuring methylmercury (MeHg) production in sediments and the water column remain limited. Understanding the relative importance of sediment and water column methylation has important implications on management strategies aimed at reducing MeHg production. In this study at the Nacimiento Reservoir, sediment (top 4 cm) and water column samples were collected from profundal and littoral zones in the winter (2016) and summer (2015). Microbial methylation and demethylation rates were measured using mercury isotope tracers in triplicate microcosms.
Description:
Mercury methylation often occurs at the active redox boundary between oxic and anoxic conditions in the sediment and the water column of lakes and reservoirs. Previous studies have suggested that the dominant zone of methylation shifts from the sediments into the water column during periods of stratification, however, studies simultaneously measuring methylmercury (MeHg) production in sediments and the water column remain limited. Understanding the relative importance of sediment and water column methylation has important implications on management strategies aimed at reducing MeHg production. In this study at the Nacimiento Reservoir, sediment (top 4 cm) and water column samples were collected from profundal and littoral zones in the winter (2016) and summer (2015). Microbial methylation and demethylation rates were measured using mercury isotope tracers in triplicate microcosms.