title: Stabilization of mercury in sediment by using biochars under reducing conditions.
abstract: Mercury (Hg) is widely distributed in different localities around the world and poses a serious health threat to humans, especially when ingested in the form of methylmercury (MeHg). Efforts have been directed toward decreasing the production of MeHg by converting Hg to stable forms. Activated carbon and biochar have been evaluated as stabilization agents for Hg in contaminated sediments. However, the long-term fate of Hg stabilized by these materials remains unclear. Here, we compare the effectiveness of Hg stabilization using two biochars prepared from switchgrass at 300°C (lowT) and 600°C (highT). Experiments were conducted by co-blending biochars and sediment for >600 d under anaerobic conditions. Aqueous concentrations of total Hg and MeHg were greatly reduced in the presence of biochars, with the exception of a spike in MeHg concentration observed at ∼440 d in the high-T biochar system. Hg co-occurs with S, Fe, Cu, and other elements within the plant structure of low-T biochar particles, but primarily on the outer surfaces of high-T biochar particles. Our results indicate that the stabilization of Hg may be through an early-stage diagenetic process, suggesting that the stabilization of Hg by biochar may be effective over long time frames.
authors.affiliation: Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave. W., Waterloo, ON, N2L 3G1, Canada.
authors.forename: Peng
authors.initials: P
authors.lastname: Liu
authors.affiliation: Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave. W., Waterloo, ON, N2L 3G1, Canada. Electronic address: ptacek@uwaterloo.ca.
authors.forename: Carol J
authors.initials: CJ
authors.lastname: Ptacek
authors.affiliation: Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave. W., Waterloo, ON, N2L 3G1, Canada.
authors.forename: David W
authors.initials: DW
authors.lastname: Blowes
authors.affiliation: CLS@APS Sector 20, PNCSRF, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439, USA; Science Division, Canadian Light Source Inc., 44 Innovation Boulevard, Saskatoon, Saskatchewan, S7N 2V3, Canada, Canada.
authors.forename: Y Zou
authors.initials: YZ
authors.lastname: Finfrock
authors.affiliation: CLS@APS Sector 20, PNCSRF, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439, USA; Science Division, Canadian Light Source Inc., 44 Innovation Boulevard, Saskatoon, Saskatchewan, S7N 2V3, Canada, Canada; Department of Physics-Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A 1S6, Canada.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Gordon
mesh_terms: D002244:Carbon / Q000032:analysis; D002606:Charcoal / Q000737:chemistry*; D003300:Copper / Q000032:analysis; D019015:Geologic Sediments / Q000737:chemistry*; D007501:Iron / Q000032:analysis; D008628:Mercury / Q000032:analysis / Q000737:chemistry*; D008745:Methylation; D008767:Methylmercury Compounds / Q000032:analysis / Q000737:chemistry*; D008897:Panicum; D045483:Rivers; D013455:Sulfur / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*
chemical_list: D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical; C540010:biochar; D002606:Charcoal; D013455:Sulfur; D002244:Carbon; D003300:Copper; D007501:Iron; D008628:Mercury
keywords: Biochar; Confocal x-ray microfluorescence imaging; Early diagenesis; Mercury; X-ray absorption spectroscopy