Abstract
Abstract. China's anthropogenic emissions of atmospheric mercury (Hg) are effectively constrained by national air pollution control and energy efficiency policies. In this study, improved methods, based on available data from domestic field measurements, are developed to quantify the benefits of Hg abatement by various emission control measures. Those measures include increased use of (1) flue gas desulfurization (FGD) and selective catalyst reduction (SCR) systems in power generation; (2) precalciner kilns with fabric filters (FF) in cement production; (3) mechanized coking ovens with electrostatic precipitators (ESP) in iron and steel production; and (4) advanced production technologies in nonferrous metal smelting. Investigation reveals declining trends in emission factors for each of these sources, which together drive a much slower growth of total Hg emissions than the growth of China's energy consumption and economy, from 679 metric tons (t) in 2005 to 750 t in 2012. In particular, estimated emissions from the above-mentioned four source types declined 3% from 2005 to 2012, which can be attributed to expanded deployment of technologies with higher energy efficiencies and air pollutant removal rates. Emissions from other anthropogenic sources are estimated to increase by 22% during the period. The species shares of total Hg emissions have been stable in recent years, with mass fractions of around 55, 39, and 6% for gaseous elemental Hg (Hg0), reactive gaseous mercury (Hg2+), and particle-bound mercury (Hgp), respectively. The higher estimate of total Hg emissions than previous inventories is supported by limited simulation of atmospheric chemistry and transport. With improved implementation of emission controls and energy saving, a 23% reduction in annual Hg emissions from 2012 to 2030, to below 600 t, is expected at the most. While growth in Hg emissions has been gradually constrained, uncertainties quantified by Monte Carlo simulation for recent years have increased, particularly for the power sector and particular industrial sources. The uncertainty (expressed as 95% confidence intervals) of Hg emissions from coal-fired power plants, for example, increased from −48–+73% in 2005 to −50–+89% in 2012. This is attributed mainly to increased penetration of advanced manufacturing and pollutant control technologies; the unclear operational status and relatively small sample sizes of field measurements of those processes have resulted in lower but highly varied emission factors. To reduce uncertainty and further confirm the benefits of pollution control and energy polices, therefore, systematic investigation of specific Hg pollution sources is recommended. The variability of temporal trends and spatial distributions of Hg emissions needs to be better tracked during the ongoing dramatic changes in China's economy, energy use, and air pollution status.
Highlights
Increasing international efforts have been made to study and control the emissions of mercury (Hg), a pollutant well known for its toxicity and long-range transport
Limited inter-annual results for one background area (Changbai Mountain in northeastern China) show reduced Hg levels (Wan et al, 2009; Fu et al, 2012b), but those differences are believed to result from changes in sampling location rather than emissions
Facing difficult challenges of severe urban and regional air pollution driven by swift economic development and enormous energy consumption, China has been implementing a series of policies in energy conservation and emission control since 2005
Summary
Increasing international efforts have been made to study and control the emissions of mercury (Hg), a pollutant well known for its toxicity and long-range transport. Available global emission inventories indicate that China has become the highest ranking nation in anthropogenic Hg emissions, attributed mainly to intensive use of fossil fuels to serve a large and rapidly growing economy (Fu et al, 2012a; Pacyna et al, 2010; Pirrone et al, 2010). Pacyna et al (2010) calculated China’s Hg emissions from fossil fuel use at 400 metric tons (t) in 2005, almost half of the country’s anthropogenic emissions. Did not sufficiently consider the differences in application of technologies, or made full use of country- or region-dependent information related to emissions. As stressed by AMAP/UNEP (2013), research on the industrial processes and technologies employed to reduce Hg emissions in different industries, and more importantly in specific countries, is a priority to improve estimation of Hg emissions
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
