Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Atmos. Chem. Phys. Discuss., 14, 24985–25026, 2014 www.atmos-chem-phys-discuss.net/14/24985/2014/ doi:10.5194/acpd-14-24985-2014 ACPD © Author(s) 2014. CC Attribution 3.0 License. 14, 24985–25026, 2014 This discussion paper is/has been under review for the journal Atmospheric Chemistry Correlation slopes and Physics (ACP). Please refer to the corresponding final paper in ACP if available. and estimated mercury emissions in Correlation slopes of GEM / CO, China X. W. Fu et al. GEM / CO2, and GEM / CH4 and estimated mercury emissions in China, South Asia, Title Page Indochinese Peninsula, and Central Asia Abstract Introduction derived from observations in northwest Conclusions References and southwest China Tables Figures J I X. W. Fu1, H. Zhang1,2, C.-J. Lin1,3,4, X. Feng1, L. X. Zhou5, and S. X. Fang5 J I 1State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, PR China Back Close 2 Graduate University of the Chinese Academy of Sciences, Beijing 100049, PR China Full Screen / Esc 3Department of Civil Engineering, Lamar University, Beaumont, Texas 77710, USA 4College of Energy and Environment, South China University of Technology, Guangzhou Printer-friendly Version 510006, China 5 Chinese Academy of Meteorological Sciences (CAMS), CMA, Beijing 100081, China Interactive Discussion 24985 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Received: 9 September 2014 – Accepted: 15 September 2014 – Published: 30 September 2014 ACPD Correspondence to: X. B. Feng ([email protected]) 14, 24985–25026, 2014 and L. X. Zhou ([email protected]) Published by Copernicus Publications on behalf of the European Geosciences Union. Correlation slopes and estimated mercury emissions in China X. W. Fu et al. Title Page Abstract Introduction Conclusions References Tables Figures J I J I Back Close Full Screen / Esc Printer-friendly Version Interactive Discussion 24986 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Abstract ACPD Correlation analysis between atmospheric mercury (Hg) and other trace gases are useful for identification of sources and constraining regional estimated Hg emissions. 14, 24985–25026, 2014 Emissions of Hg in Asia contribute significantly to the global budget of atmospheric Hg. 5 However, due to the lack of reliable data on the source strength, large uncertainties re- Correlation slopes main in the emission inventories of Hg in Asia. In the present study, we calculated the and estimated correlation slopes of GEM / CO, GEM / CO2, and GEM / CH4 for mainland China, South mercury emissions in Asia, Indochinese Peninsula, and Central Asia using the ground-based observations China at three remote sites in northwest and southwest China, and applied the values to esti- 10 mate GEM emissions in the four source regions. The geometric mean of the GEM / CO X. W. Fu et al. correlation slopes for mainland China, South Asia, Indochinese Peninsula, and Central Asia were 7.3±4.3, 7.8±6.4, 7.8±5.0, and 13.4±9.5 pg m−3 ppb−1, respectively. The values in the same source regions were 240±119, 278±164, 315±289 pg m−3 ppm−1 Title Page for the GEM / CO2 correlation slopes; and 33.3±30.4, 27.4±31.0, 23.5±15.3, and Abstract Introduction −3 −1 15 20.5±10.0 pg m ppb for the GEM / CH4 correlation slopes, respectively. These val- Conclusions References ues were the first reported correlation slopes of GEM / CO, GEM / CO2, and GEM / CH4 in four important source regions of Asia except the GEM / CO ratios in mainland China. Tables Figures The correlation slopes of GEM / CO, GEM / CO2 and GEM / CH4 in Asia were relatively higher than those observed in Europe, North America and South Africa, which may J I 20 highlight GEM emissions from non-ferrous smelting, mercury mining, natural sources and historical deposited mercury (re-emission) in Asia. Using the observed GEM / CO J I and GEM / CO2 slopes, and the recently reported emission inventories of CO and CO2, Back Close the annual GEM emissions in mainland China, South Asia, Indochinese Peninsula, and Central Asia were estimated to be in the ranges of 1071–1187 t, 340–470 t, 125 t, Full Screen / Esc 25 and 54–90 t, respectively. The estimate quantity of GEM emissions from the GEM / CH4 correlation slopes is significantly larger, which may be due to fewer common emission Printer-friendly Version sources of GEM and CH4 and large uncertainties associated with CH4 emission inven- Interactive Discussion tories in Asia and therefore lead to an overestimate of GEM emissions. Our estimates 24987 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | of GEM emissions in the four Asian regions were significantly higher (3–4 times) than the anthropogenic GEM emissions reported by recent studies. This may reflect the fast ACPD increasing anthropogenic GEM emissions in Asian countries in recent years. A prelim- 14, 24985–25026, 2014 inary assessment of natural emissions of GEM in China and other Asian regions was 5 also made and well explains the discrepancies. Correlation slopes and estimated 1 Introduction mercury emissions in China Mercury (Hg) is a persistent pollutant in the environment and poses health risks for human health mainly by consuming fish. Due to primary- and re-emissions of Hg X. W. Fu et al. from anthropogenic sources, global atmospheric Hg budget has increased significantly 10 since the industrial revolution (Mason et al., 1994). There are three major operationally defined Hg forms in the atmosphere, namely elemental gaseous mercury (GEM), Title Page gaseous oxidized mercury (GOM), and particulate bounded mercury (PBM). Knowl- edge on the anthropogenic and natural emissions of Hg to the atmosphere is important Abstract Introduction to better understanding of Hg fate in the natural environment (Lindberg et al., 2007). Conclusions References 15 Since the late 1980s, studies have been carried out to investigate the spatial and tem- poral characteristics of Hg emissions from anthropogenic (Nriagu, 1989; Pirrone et al., Tables Figures 1996, 2010; Pacyna et al., 2003, 2010; Streets et al., 2005, 2009) and natural sources (Lindberg et al., 1998; Gustin et al., 1999, 2000; Gustin, 2003; Shetty et al., 2008). J I Improved emission factors for estimating Hg release from different source categories J I 20 have significantly reduced the uncertainties (typically < 40 %) of recently reported an- Back Close thropogenic emissions (Lindberg et al., 2007; Pacyna et al., 2010; Pirrone et al., 2010). The natural emissions (including primary natural emissions and re-emissions of histor- Full Screen / Esc ically deposited Hg), however, still have large uncertainties due to poor understanding 0 of process mechanisms and a lack of reliable data on Hg air-surface exchange (Gustin Printer-friendly Version 25 et al., 2005; Schroeder et al., 2005; Selin et al., 2007; Zhang et al., 2009). Interactive Discussion Asia is the largest anthropogenic source region of Hg. It contributes approximately two-thirds of global total anthropogenic Hg emissions (Pacyna et al., 2010; Pirrone 24988 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | et al., 2010). Significant progresses have been made in the estimate of anthropogenic Hg emissions in China (Streets et al., 2005; Wu et al., 2006; Tian et al., 2011; Liang ACPD et al., 2013). The most recent estimate suggests that total anthropogenic Hg emissions 14, 24985–25026, 2014 in China increased to 1028 t in 2007 (Liang et al., 2013), nearly twofold higher than that 5 in 1995 (Streets et al., 2005). In contrast, anthropogenic Hg emissions in other Asian countries (e.g. South Asia, Southeast Asia, and Central Asia) have received little at- Correlation slopes tention. Such a lack of information limits the development of Hg emission inventories and estimated in a globally important source region. Due to the rapid economic development, anthro- mercury emissions in pogenic Hg emissions in these regions are expected to considerably contribute to the China 10 regional Hg release (Pacyna et al., 2010). Estimation of Hg emissions using observed concentrations of atmospheric GEM and X. W. Fu et al. other trace gases is a relatively novel approach for studying regional atmospheric Hg budgets. This method was firstly employed for estimating GEM emissions in the north- Title Page east USA using the GEM / CO2 correlation slopes (Lee et al., 2001). The approach 15 was further improved and then applied for estimating Hg emissions in Asia, Europe, Abstract Introduction and South Africa (Jaffe et al., 2005; Slemr et al., 2006; Brunke et al., 2012). Such Conclusions References a measurement-based method complements the regional emission inventories esti- mated by conventional statistical approaches. It also yields an estimate of total Hg Tables Figures emissions from both anthropogenic and natural sources (Jaffe et al., 2005; Slemr 20 et al., 2006). In the present study, the correlations slopes of GEM / CO, GEM / CO2, J I and GEM / CH4 were investigated using the long-term atmospheric measurements at three remote stations in northwest and southwest China. The correlation slopes were J I classified into four source regions in Asia (mainland China, South Asia, Indochinese Back Close Peninsula, and Central Asia) through trajectory analysis for estimating atmospheric Hg Full Screen / Esc 25 emissions. This work is aimed to fill the knowledge gaps in our understanding on Asian Hg emissions. Printer-friendly Version Interactive Discussion 24989 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 2 Experimental ACPD 2.1 Observational sites 14, 24985–25026, 2014 In this study, observations were conducted at three remote sites in northwest and southwest China: Mt. Waliguan Baseline Observatory, Shangri-La station and Mt. Ailao ◦ ◦ Correlation slopes 5 station (Fig. 1). The Mt. WLG Observatory (WLG, 100.898 E, 36.287 N, 3816 m a.s.l.) and estimated is one of the World Meteorological Organization’s (WMO) Global Atmospheric Watch mercury emissions in (GAW) Baseline Stations which is situated at the summit of Mt.