As the Minamata Convention on Mercury comes into effect, controlling atmospheric mercury (Hg) emissions has become a compulsory goal. This study determined the mitigation options for the five ...Convention specified sources by considering their reduction potential of Hg emissions and the impact of future technology changes on emitted Hg forms and cross-media releases. Hg emissions will be reduced from 371 t in 2015 to 242 t in 2020 mainly by applying multipollutant control measures. Hg emissions will be reduced to 71 t in 2030 mainly with alternative measures and specific Hg removal measures (SMR). Alternative measures are effective for the studied sources except waste incineration (WI). SMR is preferentially recommended in cement clinker production due to the benefit of sectoral emissions and local deposition. Stringent requirements of Hg emission control will promote the use of SMR in WI. In case of nonferrous metal smelting (NFMS), only 8.7 t of Hg emissions will be reduced by SMR. However, the cobenefit of Hg reduction in sulfuric acid and local deposition will increase the relevance. On the contrary, applying SMR in coal-fired power plants (CFPPs) and coal-fired industrial boilers (CFIBs) requires comprehensive evaluation in terms of cost benefit and cross-media effect.
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IJS, KILJ, NUK, PNG, UL, UM
Mercury pollution control has become a global goal. The accurate estimate of long-term mercury emissions in China is critical to evaluate the global mercury budget and the emission reduction ...potentials. In this study, we used a technology-based approach to compile a consistent series of China’s atmospheric mercury emissions at provincial level from 1978 to 2014. China totally emitted 13 294 t of anthropogenic mercury to air during 1978–2014, in which gaseous elemental mercury, gaseous oxidized mercury, and particulate-bound mercury accounted for 58.2%, 37.1%, and 4.7%, respectively. The mercury removed during this period were 2085 t in coal-fired power plants (counting 49% of mercury input), 7259 t in Zn smelting (79%), 771 t in coal-fired industrial boilers (25%), and 658 t in cement production plants (27%), respectively. Annual mercury emissions increased from 147 t in 1978 to 530 t in 2014. Both sectoral and spatial emissions of atmospheric mercury experienced significant changes. The largest mercury emission source evolved from coal-fired industrial boilers before 1998, to zinc smelting during 1999–2004, coal-fired power plants during 2005–2008, finally to cement production after 2009. Coal-fired industrial boilers and cement production have become critical hotpots for China’s mercury pollution control.
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Mercury (Hg) is a potentially harmful trace element in the environment and one of the World Health Organization's foremost chemicals of concern. The threat posed by Hg contaminated soils to humans is ...pervasive, with an estimated 86 Gg of anthropogenic Hg pollution accumulated in surface soils worldwide. This review critically examines both recent advances and remaining knowledge gaps with respect to cycling of mercury in the soil environment, to aid the assessment and management of risks caused by Hg contamination. Included in this review are factors affecting Hg release from soil to the atmosphere, including how rainfall events drive gaseous elemental mercury (GEM) flux from soils of low Hg content, and how ambient conditions such as atmospheric O3 concentration play a significant role. Mercury contaminated soils constitute complex systems where many interdependent factors, including the amount and composition of soil organic matter and clays, oxidized minerals (e.g. Fe oxides), reduced elements (e.g. S2−), as well as soil pH and redox conditions affect Hg forms and transformation. Speciation influences the extent and rate of Hg subsurface transportation, which has often been assumed insignificant. Nano-sized Hg particles as well as soluble Hg complexes play important roles in soil Hg mobility, availability, and methylation. Finally, implications for human health and suggested research directions are put forward, where there is significant potential to improve remedial actions by accounting for Hg speciation and transportation factors.
•Mercury contaminated soils constitute complex systems with many interdependent factors.•Speciation, complexation and particle size play important roles in subsurface transport.•Rainfall events and atmospheric ozone levels influence Hg flux to the atmosphere.•Implications for human health and suggested research directions are put forward.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
China is the largest contributor to global atmospheric mercury (Hg), and accurate emission inventories in China are needed to reduce large gaps existing in global Hg mass balance estimates and assess ...Hg effects on various ecosystems. The China Atmospheric Mercury Emission (CAME) model was developed in this study using probabilistic emission factors generated from abundant on-site measurements and literature data. Using this model, total anthropogenic Hg emissions were estimated to be continuously increasing from 356 t in 2000 to 538 t in 2010 with an average annual increase rate of 4.2%. Industrial coal combustion, coal-fired power plants, nonferrous metal smelting, and cement production were identified to be the dominant Hg emission sources in China. The ten largest contributing provinces accounted for nearly 60% of the total Hg emissions in 2010. Speciated Hg emission inventory was developed over China with a grid-resolution of 36 × 36 km, providing needed emission fields for Hg transport models. In this new inventory, the sectoral Hg speciation profiles were significantly improved based on the latest data from field measurements and more detailed technology categorization. The overall uncertainties of the newly developed inventory were estimated to be in the range of −20% to +23%.
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Intentional use of mercury (Hg) is an important contributor to the release of Hg into the environment. This study presents the first inventory of material flow for intentional use of Hg in China. The ...total amount of Hg used in China increased from 803 ± 95 tons in 2005 to its peak level of 1272 ± 110 tons in 2011. Vinyl chloride monomer (VCM) production is the largest user of Hg, accounting for over 60% of the total demand. As regulations on Hg content in products are tightening globally against the background of the Minamata Convention, the total demand will decrease. Medical devices will likely still use a significant amount of Hg and become the second largest user of Hg if no proactive measures are taken. Significant knowledge gaps exist in China for catalyst recycling sector. Although more than half of the Hg used is recycled, this sector has not drawn enough attention. There are also more than 200 tons of Hg that had unknown fates in 2011; very little information exists related to this issue. Among the final environmental fates, landfill is the largest receiver of Hg, followed by air, water, and soil.
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As the largest coal consumer in China, the coal-fired power plants have come under increasing public concern in regard to atmospheric mercury pollution. This study developed an up-to-date and ...high-resolution mercury emission inventory of Chinese coal-fired power plants using a unit-based method that combined data from individual power plants, provincial coal characteristics, and industry removal efficiencies. National mercury emissions in 2015 were estimated at 73 tons, including 54 tons of elemental mercury, 18 tons of gaseous oxidized mercury and 1 ton of particle-bound mercury. Pulverized coal boilers emitted 65 tons, mainly in the coastal provinces and coal-electricity bases. Circulating fluidized bed boilers emitted 8 tons, mainly in Inner Mongolia and Shanxi Province. The average mercury emission intensity over the Chinese mainland was 18.3 g/GWh, which was similar to the limit for low-rank coal-fired units in the United States. The overall uncertainty of national mercury emission was estimated to be −19% to 20%, with the mercury content in coal being the major contributor. In most provinces, monthly mercury emissions generally peaked in December and August. However, monthly partition coefficients of southwest China were obviously lower than other regions from June to October due to the high proportion of hydropower generation.
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China took aggressive air pollution control measures from 2013 to 2017, leading to the mitigation of atmospheric mercury pollution as a cobenefit. This study is the first to systematically evaluate ...the effect of five major air pollution control measures in reducing mercury emissions, the total gaseous mercury (TGM) concentration and mercury deposition flux (FLX) for unit emissions reduction. From 2013 to 2017, China’s mercury emissions decreased from 571 to 444 tons, resulting in a 0.29 ng m–3 decrease in the TGM concentration, on average, and in a 17 μg m–2 yr–1 decrease in FLX. Ultralow emission renovations of coal-fired power plants are identified as the most effective emission abatement measure. As a result of this successful measure, coal-fired power plants are no longer the main mercury emitters. In 2017, the cement clinker sector became the largest emitter due to the use of less effective mercury removal measures. However, in terms of the mitigated TGM concentration and FLX levels per unit emission abatement, newly built wet flue gas desulfurization (WFGD) systems in coal-fired industrial boilers have become particularly effective in decreasing FLX levels. Therefore, to effectively reduce atmospheric mercury pollution in China, prioritizing mercury emissions control of cement clinkers and coal-fired industrial boilers is recommended.
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•The heterogeneous oxidation process is confirmed to be Eley–Rideal mechanism.•The unburned carbon (UBC) is important for mercury oxidation and adsorption.•Mercury can be adsorbed by Al2O3, Fe2O3 and ...TiO2, not CaO and MgO.•No metallic oxides catalyzed the mercury oxidation in simulated flue gas.
Coal combustion is a predominant anthropogenic source of atmospheric mercury emissions. The oxidation and adsorption on the surface of fly ashes are crucial to mercury control. In this study, we discussed the mercury adsorption/oxidation mechanisms on the surface of fly ashes and different roles of organic and inorganic compositions based on the experimental results of a fixed-bed reactor and temperature programmed decomposition technique (TPDT). The results indicated that the fly ashes played significant roles in mercury oxidation and adsorption. The residual Cl element on the surface of fly ashes after pretreatment at 650°C contributed to the oxidation and adsorption of mercury. The heterogeneous oxidation process in this study has been confirmed to follow an Eley–Rideal mechanism. Unburned carbon (UBC) is important for mercury oxidation and adsorption on fly ashes. O2 promoted mercury adsorption, but not oxidation. The adsorption capacity was greatly increased in a simulated flue gas, and the oxidation rate was 60%. Al2O3, Fe2O3 and TiO2 were capable of adsorbing mercury. Among these compounds, Al2O3 displayed the largest adsorption capacity. Mercury adsorption did not occur on the surface of CaO and MgO. The flue gas compositions exhibited no influences on the adsorption capacity for the above five metallic oxides. No metallic oxides catalyzed the mercury oxidation regardless of the flue gas composition.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Iron and steel production (ISP) is one of the significant atmospheric Hg emission sources in China. Atmospheric mercury (Hg) emissions from ISP during 2000–2015 were estimated by using a ...technology-based emission factor method. To support the application of this method, databases of Hg concentrations in raw materials, technology development trends, and Hg removal efficiencies of air pollution control devices (APCDs) were constructed through national sampling and literature review. Hg input to ISP increased from 21.6 t in 2000 to 94.5 t in 2015. In the various types of raw materials, coking coal and iron concentrates contributed 35–46 and 25–32 % of the total Hg input. Atmospheric Hg emissions from ISP increased from 11.5 t in 2000 to 32.7 t in 2015 with a peak of 35.6 t in 2013. Pollution control promoted the increase in average Hg removal efficiency, from 47 % in 2000 to 65 % in 2015. During the study period, sinter/pellet plants and blast furnaces were the largest two emission processes. However, emissions from roasting plants and coke ovens cannot be ignored, which accounted for 22–34 % of ISP's emissions. Overall, Hg speciation shifted from 50/44/6 (gaseous elemental Hg (Hg0)/gaseous oxidized Hg (HgII)/particulate-bound Hg (Hgp)) in 2000 to 40/59/1 in 2015, which indicated a higher proportion of Hg deposition around the emission points. Future emissions of ISP were expected to decrease based on the comprehensive consideration crude-steel production, steel scrap utilization, energy saving, and pollution control measures.
Mercury (Hg) is a toxic and persistent pollutant and has long-term impacts on ecological systems and human health. Coal-fired power plants (CFPPs) are the main source of anthropogenic Hg emission, ...and the emitted atmospheric Hg is deposited to the surrounding environments which causes soil pollution. To assess the effects of atmospheric Hg from CFPPs in China on the temperate steppe, Hg contents in the topsoil and subsoil were analyzed for samples collected from 80 sites in central Inner Mongolia during 2012–2015. The average content of Hg in topsoil and subsoil were 14.9 ± 10.4 μg kg−1 and 8.9 ± 5.8 μg kg−1, respectively. The principal components analysis (PCA) indicated that the soil organic matter content and atmospheric deposition were the main factors determining soil Hg content in Inner Mongolia. We used the power plant impact factor (PPIF) to evaluate the impacts of the surrounding CFPPs. The PPIF results showed the most positive correlation with Hg content in topsoil at more than 400 km distances, indicating that the contribution of the long-range transport of Hg emitted from CFPPs is regional in scale. Considering the potential of Hg accumulation in soil, long-term and regional measurements of soil Hg and stricter emission-limit standards for power plants should be implemented to control soil Hg pollution in China.
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•Background mercury contents in topsoil (14.9 ± 10.4 μg kg−1) and subsoil (8.9 ± 5.8 μg kg−1) of temperate steppe were measured.•TOC was the main factor influencing the original soil Hg content while atmospheric deposition increased the Hg in topsoil.•The power plant impact factor provided quick assessment for the impact of coal fired power plants on soil Hg pollution.
A soil mercury measurement and a semi-quantified model was conducted to investigate the influence of atmospheric deposition on grassland soil Hg in Chinas.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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