Investigation of the Potential for Mercury Release from Flue Gas Desulfurization Solids Applied as an Agricultural Amendment

The potential for beneficial use of flue gas desulfurization–derived gypsum (FGDG), a coal combustion byproduct, as an agricultural soil amendment is currently being debated. This study investigated the hypothesis that Hg released to air from FGDG will be reduced when amended to planted and bare soils. The potential for enhanced methylmercury (MeHg) production and Hg uptake by plants in soils amended with FGDG was also investigated. Flue gas desulfurization–derived gypsum from three sources was homogenized into three soils at 4.5, 45, and 170 t ha−1 and applied at 4.9 t ha−1 as a thin layer to simulate tilled and no‐till applications, respectively. Twenty‐four‐hour Hg flux was measured from unamended and FGDG‐amended soils on a seasonal time step over 1 yr and after disturbing, watering, and planting. Methylmercury in soil, irrigation drainage, and total Hg in plant tissues were quantified. Results should be interpreted within the confines of the experimental setting and materials used for this study. Total Hg concentrations in soils, homogenized with FGDG, were below that considered representative of soil with background values (