Characterizing the composition of mercury (Hg) isotopes in the atmospheric emissions of cement plants is critical to understand the global circulation of Hg because large quantities of Hg are released from this source annually. A pre-calciner cement plant in Guizhou Province in Southwest China was selected to investigate the mass dependent fractionation (MDF) and mass independent fractionation (MIF) of Hg in the entire production process and the speciated Hg isotope composition in stack gas. Significant MDF and insignificant MIF were observed in this cement plant. Different raw/correction materials have delta Hg-202 signals ranging from -1.68 to -2.19 parts per thousand. Raw meal is featured with lighter Hg (delta Hg-202 -2.83 0.18 parts per thousand) as results of Hg circulation and accumulation during the clinker production. Cement products possess negative delta Hg-202 values (-1.98 0.02 parts per thousand) due to the input of light delta Hg-202 isotopes through additives/retarder limestone, and fly ash and gypsum from coal-fired power plant (CFPPs). Speciated Hg isotopes in the stack gas of the kiln tail and kiln head show no significant differences, and delta(202) H.and Delta Hg-199 in the discharged flue gas averaged at -2.03 0. 31 parts per thousand and -0.03 0.07 parts per thousand, respectively, which has negative delta Hg-202 characteristics with other anthropogenic sources.

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