Stable isotope composition of mercury forms in flue gases from a typical coal-fired power plant, Inner Mongolia, northern China

Isotopic Composition of Gaseous Elemental Mercury in the Marine Boundary Layer of East China Sea

“…This discrepancy is possibly caused by other anthropogenic Hg sources. Implementation of APCDs (i.e., selective catalytic reduction, electrostatic precipitators, and wet flue gas desulfurization) during coal combustion is the major factor inducing significant Hg isotope MDF during coal combustion (Sun, Heimburger, et al, ; Tang et al, ). In China, the implementation level of selective catalytic reductions, electrostatic precipitators, and/or wet flue gas desulfurization in CFPPs is 100%, while the level in coal combustion in industrial boiler and domestic heating is <12% (Wu et al, ).…”

“…In China, the implementation level of selective catalytic reductions, electrostatic precipitators, and/or wet flue gas desulfurization in CFPPs is 100%, while the level in coal combustion in industrial boiler and domestic heating is <12% (Wu et al, ). Therefore, GEM emitted from industrial boilers and domestic heating in China should have much lower δ 202 Hg compared to that (0.54 ± 0.25‰, 1σ) of CFPPs sufficiently equipped by APCDs (Tang et al, ). In addition, mean (±1σ) δ 202 Hg of Hg in limestone, Hg ores, and biomass in China are −1.40 ± 0.51‰, −0.79 ± 0.14‰, and −2.97 ± 0.54‰, respectively, lower than those (−0.55 ± 0.58‰, −0.59 ± 0.81‰, and −2.22 ± 0.22‰, respectively) found in other regions worldwide (Demers et al, ; Smith et al, ; Sonke et al, ; Sun et al, ; Thibodeau et al, ; Yin et al, ; Yu et al, ; Zheng et al, ).…”

“…These sources account for ~62% of the total anthropogenic GEM emissions in China (Zhang et al, ), sufficiently significant to cause a negative shift in domestic GEM δ 202 Hg. Taking into account the proportions of GEM emission of the specific source sectors in total anthropogenic emissions in China and their δ 202 Hg and Δ 199 Hg signatures in Table S4 in the supporting information (Fu et al, ; Sun et al, ; Tang et al, ; Wang et al, ; Yin et al, , , ; Yu et al, ; Zhang et al, ), we estimate that the mean (±1σ) δ 202 Hg and Δ 199 Hg for anthropogenic GEM emissions in China are −0.82 ± 0.63‰ and −0.04 ± 0.13% (Table S4), respectively. The estimated δ 202 Hg of GEM emissions in China is comparatively lower than the mean value (−0.59‰) of global anthropogenic sources predicted by Sun et al (Sun et al, ) but comparatively higher than that (−1.79 ± 0.24‰, 1σ) estimated using the mixing diagram.…”

“…Mean (±1σ) Δ 199 Hg in feed coal, zinc ores, limestone, Hg ores, and biomass in China are À0.03 ± 0.16‰, 0.02 ± 0.06‰, À0.01 ± 0.07‰, 0.01 ± 0.02‰, and À0.19 ± 0.10‰, respectively, significantly higher than those (À0.16 ± 0.18‰, À0.04 ± 0.06‰, À0.03 ± 0.08‰, À0.04 ± 0.07‰, and À0.28 ± 0.09‰, respectively) in the rest of the world (paired t test, p < 0.05, T = 3.7, n = 5). Assuming that isotopic signatures of GEM emissions from major anthropogenic sources resemble the MIF signatures of source materials Sun et al, 2014Sun et al, , 2016Tang et al, 2017), Δ 199 Hg of atmospheric GEM in mainland China, influenced by the regional anthropogenic sources, should be higher than the GEM Δ 199 Hg in other regions worldwide, as shown in Figure 2. Coal combustion in CFPPs and nonferrous metal smelting are the two important sources of atmospheric GEM in China and other regions worldwide (Pirrone et al, 2010;Zhang et al, 2015).…”

“…Application rates of APCDs in industrial and residential coal combustion are much lower than CFPPs (Wu et al, ) and would therefore not induce significant positive shifts of δ 202 Hg of emitted GEM relative to feed source materials as that of CFPPs (Sun et al, ). Isotopic compositions of GEM emitted from zinc smelting and cement production were estimated to have much more negative δ 202 Hg values than that emitted from CFPPs (Sun et al, ; Tang et al, ). As a consequence, isotopic signatures of Hg emitted from Chinese anthropogenic sources would differ from those in North America and Europe.…”