Control of mercury and methylmercury in contaminated sediments using biochars: A long-term microcosm study

The final publication is available at Elsevier via https://dx.doi.org/10.1016/j.apgeochem.2018.02.004 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/The effectiveness of activated carbon and four types of biochar, switchgrass (300 °C and 600 °C), poultry manure (600 °C), and oak (∼700 °C) with respect to mercury (Hg) and methylmercury (MeHg) control was assessed in microcosm experiments carried out for 524 d. Early in the study (<30 d), minimal differences in concentrations of <0.45-μm filtered total Hg (THg) in control and 5% biochar-amended systems were observed. At later stages, THg concentrations in the amended systems decreased to 8–80% of concentrations in the sediment controls. Aqueous concentrations of MeHg were generally lower in the amended systems than in the controls, with an initial peak in MeHg concentration corresponding to the onset of iron and sulfate reduction (∼40 d) and a second peak to methanogenic conditions (∼400 d). Pyrosequencing analyses indicate the microbial communities initially associated with fermenters and later shifted to iron-reducing bacteria (FeRB), sulfate-reducing bacteria (SRB), and methanogens. These analyses also indicate the existence of 12 organisms associated with Hg methylation in all systems. Community shifts were correlated with changes in the concentrations of carbon sources (dissolved organic carbon (DOC) and organic acids) and electron acceptors (NO3−, Fe, and SO42−). Co-blending of biochars with Hg-contaminated sediment can be an alternative remediation method for controlling the release of Hg and MeHg, but the potential for Hg methylation under some conditions requires consideration.Natural Sciences and Engineering Research Council of CanadaCanada Research ChairsE. I. du Pont de Nemours and Compan

Microbial processes with the potential to mobilize As from a circumneutral-pH mixture of flotation and roaster tailings

The Northwest Tailings Containment Area at the inactive Giant Mine (Canada) contains a complex mixture of arsenic-containing substances, including flotation tailings (84.8 wt%; with 0.4 wt% residual S), roaster calcine wastes (14.4 wt% Fe oxides), and arsenic trioxide (0.8 wt%) derived from an electrostatic precipitator as well as As-containing water (21.3 ± 4.1 mg L−1 As) derived from the underground mine workings. In the vadose zone the tailings pore water has a pH of 7.6 and contains elevated metal(loid)s (2.37 ± 5.90 mg L−1 As); mineral oxidizers account for 2.5% of total 16S rRNA reads in solid samples. In the underlying saturated tailings, dissolved Fe and As concentrations increase with depth (up to 72 and 20 mg L−1, respectively), and the mean relative abundance of Fe(III)-reducers is 0.54% of total reads. The potential for As mobilization via both reductive and oxidative (bio)processes should be considered in Giant Mine remediation activities. The current remediation plan includes installation of an engineered cover that incorporates a geosynthetic barrier layer

Warm-up phenomenon in myotonia associated with the V445M sodium channel mutation

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Data on removal kinetics of pharmaceutical compounds, artificial sweeteners, and perfluoroalkyl substances from water using a passive treatment system containing zero-valent iron and biochar

The data presented in this paper relate to the research paper “Removal of pharmaceutical compounds, artificial sweeteners, and perfluoroalkyl substances from water using a passive treatment system containing zero-valent iron and biochar” [1]. Four columns packed with different ratios of reactive media, including silica sand (SS), zero-valent iron (ZVI), and biochar (BC), were evaluated for simultaneous removal of 14 emerging contaminants from water. The target emerging contaminants included eight pharmaceuticals (carbamazepine, caffeine, sulfamethoxazole, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine, ibuprofen, gemfibrozil, and naproxen), four artificial sweeteners (acesulfame-K, sucralose, saccharin, and cyclamate), and two perfluoroalkyl substances (perfluorooctanoic acid and perfluorooctane sulfonic acid). The samples for target contaminant analysis were collected from the influent, effluent, and profile (along the flow direction) ports of each column. The removal data (concentration vs. residence time) for each target contaminant were fitted to the first-order (exponential decay equation) or zero-order (linear equation) model using SigmaPlot. The removal rate, removal rate constant (kobs), mass normalized rate constant (kM), surface area normalized rate constant (kSA, specific reaction rate constant), and half-life (t0.5) of target contaminants in Columns ZVI, BC, and (ZVI + BC) were calculated and summarized in this dataset.Natural Sciences and Engineering Research Council of Canada