Investigation of Local Mercury Deposition from a Coal-Fired Power Plant Using Mercury Isotopes

Abstract

Coal combustion accounts for approximately two-thirds of global anthropogenic mercury (Hg) emissions. Enhanced deposition of Hg can occur close to coal-fired utility boilers (CFUBs), but it is difficult to link specific point sources with local deposition. Measurement of Hg stable isotope ratios in precipitation holds promise as a tool to assist in the identification of local Hg deposition related to anthropogenic emissions. We collected daily event precipitation samples in close proximity to a large CFUB in Crystal River, Florida. Precipitation samples collected in Crystal River were isotopically distinct and displayed large negative δ(202)Hg values (mean = -2.56‰, 1 SD = 1.10‰, n = 28). In contrast, precipitation samples collected at other sites in FL that were not greatly impacted by local coal combustion were characterized by δ(202)Hg values close to 0‰ (mean = 0.07‰, 1 SD = 0.17‰, n = 13). These results indicate that, depending on factors such as powdered coal isotopic composition and efficiency of Hg removal from flue gas, Hg deposited near CFUBs can be isotopically distinct. As this tool is further refined through future studies, Hg stable isotopes may eventually be used to quantify local deposition of Hg emitted by large CFUBs.

Historical (1850–2010) mercury stable isotope inventory from anthropogenic sources to the atmosphere

“…Further experimental and observational work on Hg isotope MDF during coal combustion, metal refining and liquid Hg 0 use is needed to confirm the presented conceptual models. High-precision Hg isotope measurement of total gaseous Hg (TGM, GEM+GOM) and precipitation Hg has been reported for several N-American and European regions (Chen et al, 2012;Demers et al, 2013Demers et al, , 2015Donovan et al, 2013;Fu et al, 2014;Gratz et al, 2010;Sherman et al, 2010Sherman et al, , 2012Sherman et al, , 2015Wang et al, 2015). Global TGM is enriched in the heavy isotopes (d 202 Hg=0.51 ± 0.41 ‰, 1SD) (Demers et al, 2013(Demers et al, , 2015Fu et al, 2014;Gratz et al, 2010;Sherman et al, 2010) compared to our model estimated GEM emissions (Table 1).…”

“…During the thermal processing of source materials, Hg in source materials is transformed into GEM, GOM and PBM in generated flue gases by a series of physicochemical reactions (oxidation, reduction, adsorption, diffusion etc.). These phase and redox transformations of Hg in high-temperature facilities are expected to induce significant Hg isotope MDF, but no photochemical MIF (Sherman et al, 2012;Sonke et al, 2010;Sun et al, 2013; (Biswas et al, 2008;Lefticariu et al, 2011;Sherman et al, 2012;Sun et al, 2013Sun et al, , 2014aSun et al, , 2014bYin et al, 2014a). In contrast, only a limited number of oil sand samples from Athabasca, Canada have been reported .…”

“…The data points either greater than the upper quartile + 1.5 IQR or less than the lower quartile-1.5 IQR are considered to be extreme values. Data sources: coal (Biswas et al, 2008;Lefticariu et al, 2011;Sherman et al, 2012;Sun et al, 2013Sun et al, , 2014aSun et al, , 2014bYin et al, 2014a); oil ; cinnabar (Cooke et al, 2013;Foucher et al, 2009;Gehrke et al, 2011;Smith et al, 2005Smith et al, , 2008Stetson et al, 2009;Yin et al, 2013); Commercial liquid Hg 0 Estrade et al, 2009;Foucher et al, 2009;Laffont et al, 2011;Mead et al, 2013;Sonke et al, 2008); Zn ores (Smith, 2010;Sonke et al, 2010); Au ores (Smith, 2010); silicate rocks (Blum and Anbar, 2010;North, 2011;Sun et al, 2014b;Zhang et al, 2013Zhang et al, , 2014; limestone (sampled from Huainan Basin, China, this study); volcanic gases (this study; Zambardi et al, 2009 144 sector/fuel/technology combinations for combustion sources are designated to coal combustion, and all these combinations have their corresponding Hg species emission characteristics. Here, we improve the previous estimates on isotope composition of speciated Hg from coal combustion as follows: 1) APCDs are divided into five types: cyclone, scrubber, fiber filter (FF), electrostatic precipitator (ESP), flue gas desulfurization (FGD).…”

Uncertainties in Atmospheric Mercury Modeling for Policy Evaluation

“…Hg isotopes can undergo mixing and fractionation by two types of pathways that impart distinct Hg isotopic compositions on natural environmental samples. Studies have shown distinct Hg isotopic compositions in samples those impacted by coal-fired power plants, metal refineries, and gold amalgamation [110][111][112]. Significant fractionations of Hg isotopes have been observed during AMDEs [88] and in-plume reduction [113] as well as in background atmospheric conditions via photochemical reduction, oxidation, and sorption to particles [114•].…”

Sedimentary records of mercury stable isotopes in Lake Michigan

“…202 Hg and D 199 Hg values have been reported in environmentally relevant matrices such as rocks (Smith et al, 2008), mineral deposits (Hintelmann and Lu, 2003;Smith et al, 2005Smith et al, , 2008Stetson et al, 2009;Sonke et al, 2010), coals (Biswas et al, 2008;Lefticariu et al, 2011;Sun et al, 2014;Yin et al, 2014b), soils (Biswas et al, 2008;Zhang et al, 2013;Feng et al, 2013), sediments (Gehrke et al, 2011;Foucher and Hintelmann, 2009;Feng et al, 2010;Liu et al, 2011;Bartov et al, 2013;Donovan et al, 2013;Ma et al, 2013;Yin et al, 2013aYin et al, , 2015, water (Štrok et al, 2014), air (Demers et al, 2013;Rolison et al, 2013), precipitation (Gratz et al, 2010;Chen et al, 2012;Demers et al, 2013;Sherman et al, 2011Sherman et al, , 2015 and biological samples Blum et al, 2013;Demers et al, 2013;Yin et al, 2013b). With well-defined source signatures, researchers may estimate the relative contribution of sources of Hg through the utilization of binary and/or triple mixing models (Foucher and Hintelmann, 2009;Feng et al, 2010;Liu et al, 2011;Bartov et al, 2013;Donovan et al, 2013;Ma et al, 2013;…”