Regional distribution and emissions of mercury in east Asia: A modeling analysis of Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia) observations (original) (raw)

Observations of atmospheric mercury in China: a critical review

Atmospheric Chemistry and Physics Discussions

China is presently the largest contributor of global anthropogenic Hg emission to the atmosphere. Over the past two decades, extensive studies have been conducted to characterize the concentration and speciation of atmospheric Hg in China. These studies provide important insight into the spatial and temporal distributions of atmospheric Hg species in China through ground-based measurements at a wide range of altitude over diverse geographical locations, and cruise and flight campaigns. In this critical review, we synthesize the available data to date to delineate the spatial and temporal patterns of atmospheric Hg, the long-range transport pattern of atmospheric Hg, and the impacts of Hg emissions on atmospheric Hg distribution and deposition in China. Atmospheric Hg species in China are substantially elevated compared to the background values in the Northern Hemisphere. The highly elevated Hg levels in Chinese urban areas were derived from local and regional anthropogenic and natur...

Atmospheric speciated mercury concentrations on an island between China and Korea: sources and transport pathways

Atmospheric Chemistry and Physics Discussions, 2015

As a global pollutant, mercury (Hg) is of particular concern in East Asia where anthropogenic emissions are the largest. In this study, speciated Hg concentrations were measured in the western most island in Korea, located between China and the Korean mainland to identify the importance of local, regional and distant Hg sources. Various tools including correlations with other pollutants, conditional probability function, and back-trajectory based analysis consistently indicated that Korean sources were important for gaseous oxidized mercury (GOM) whereas, for total gaseous mercury (TGM) and particulate bound mercury (PBM), long-range and regional transport were also important. A trajectory cluster based approach considering both Hg concentration and the fraction of time each cluster was impacting the site was developed to quantify the effect of Korean sources and out-of-Korean source. This analysis suggests that Korean sources contributed approximately 55 % of the GOM and PBM while there were approximately equal contributions from Korean and out-of-Korean sources for the TGM measured at the site. The ratio of GOM / PBM decreased when the site was impacted by long-range transport, suggesting that this ratio may be a useful tool for identifying the relative significance of local sources vs. long-range transport. The secondary formation of PBM through gas-particle partitioning with GOM was found to be important at low temperatures and high relative humidity.

Temporal distribution and potential sources of atmospheric mercury measured at a high-elevation background station in Taiwan

Atmospheric Environment, 2010

Measurements of gaseous elemental mercury (GEM), reactive gaseous mercury (RGM), and particulate mercury (PHg) have been conducted at Lulin Atmospheric Background Station (LABS) in Taiwan since April 2006. This was the first long-term free tropospheric atmospheric Hg monitoring program in the downwind region of East Asia, which is a major Hg emission source region. Between April 13, 2006 and December 31, 2007, the mean concentrations of GEM, RGM, and PHg were 1.73 ng m À3 , 12.1 pg m À3 , and 2.3 pg m À3 , respectively. A diurnal pattern was observed for GEM with afternoon peaks and nighttime lows, whereas the diurnal pattern of RGM was opposite to that of GEM. Spikes of RGM were frequently observed between midnight and early morning with concurrent decreases in GEM and relative humidity and increases in O 3 , suggesting the oxidation of GEM and formation of RGM in free troposphere (FT). Upslope movement of boundary layer (BL) air in daytime and subsidence of FT air at night resulted in these diurnal patterns. Considering only the nighttime data, which were more representative of FT air, the composite monthly mean GEM concentrations ranged between 1.06 and 2.06 ng m À3 . Seasonal variation in nighttime GEM was evident, with lower concentrations usually occurring in summer when clean marine air masses prevailed. Between fall and spring, air masses passed the East Asian continent prior to reaching LABS, contributing to the elevated GEM concentrations. Analysis of GEM/CO correlation tends to support the argument. Good GEM/CO correlations were observed in fall, winter, and spring, suggesting influence of anthropogenic emission sources. Our results demonstrate the significance of East Asian Hg emissions, including both anthropogenic and biomass burning emissions, and their long-range transport in the FT. Because of the pronounced seasonal monsoon activity and the seasonal variation in regional wind field, export of the Asian Hg emissions to Taiwan occurs mainly during fall, winter, and spring.

Correlation Analysis, Transportation Mode of Atmospheric Mercury and Criteria Air Pollutants, with Meteorological Parameters at Two Remote Sites of Mountain and Offshore Island in Asia

Aerosol and Air Quality Research, 2016

This study presents a comparison of trace (Hg) and criteria (CO, SO 2 , NO x , O 3 and PM 10) air pollutants monitored at two remote sites with the same latitude but different altitude: Mt. Lulin and the Penghu Islands, in Taiwan from 2011 to 2012. A filtering technique was comprehensively applied to distinguish the climatic characteristics of the two remote sites, as well as to determine their discriminant factor. The concentrations of air pollutants monitored at Mt. Lulin were generally lower than those at the Penghu Islands, with the exception of O 3 concentration. PM 10 and NO x were the important factors that can distinguish two clusters of measurement data at the two remote sites, and a criteria discriminant factor of atmospheric parameters derived from these two air pollutants. For both high-and low-frequency patterns, the concentrations of NO x and PM 10 exhibit significant differences between the two remote sites. However, O 3 concentrations showed almost no differences between these two remote sites, implying that the pattern for the formation and transportation of O 3 at these two sites resulted from similar mechanisms. Moreover, atmospheric mercury (TGM) had a very good linear correlation with CO. The diurnal variation of Hg concentration was dramatic at the Penghu Islands, while it appeared as low as the North Hemisphere background mercury concentration at Mt. Lulin, indicating that they were not formed via the mechanism modes. This study thus proposed "scenario mercury" and "background mercury" for interpreting this interesting phenomenon.

Total gaseous mercury in the atmosphere of Guiyang, PR China

Science of The Total Environment, 2003

Four measurement campaigns were carried out to monitor total gaseous mercury (TGM) at one site in Guiyang City, PR China in the following periods, respectively. High temporal resolved data were obtained by using automated mercury analyzers Gardis 1A and Tekran 2537A. TGM data from all measurement periods followed the typical log normal distribution pattern. The geometric mean of TGM from different seasons were 8. 56, 7.45, 5.20 and 8.33 ng m in spring 2000, winter 2001, summer 2001 and autumn 2001, respectively. The overall average TGM covering y3 the sampling periods was 7.39 ng m , which is significantly elevated comparing to global background of y3 approximately 1.5-2.0 ng m . The major anthropogenic atmospheric mercury emission sources differed significantly y3

Measurements of atmospheric mercury in Shanghai during September 2009

Atmospheric Chemistry and Physics, 2011

We report on total gaseous mercury (TGM) measurements made in Pudong, Shanghai in August/September 2009. The average TGM was 2.7±1.7 ng m −3 . This represents about 90% of the total atmospheric mercury. This is an underestimate for an annualmean concentration because the meteorology in September favored predominantly 5 easterly oceanic air, replaced in other seasons by airflow from industrial areas. The observed TGM follows a pattern seen in other cities around the world: a background elevated over mean hemispheric background (1.5 ng m −3 ), and pollution plumes of different magnitude and duration, interspersed with very sharp spikes of high concentration (60 ng m −3 ). The September 2009 Shanghai measurements are lower than those 10 reported for most other Chinese cities and Mexico City, and similar to concentrations found in some Asian and in North American cities. Such comparisons are tenuous because of differences in season and year of the respective measurements. We find that the observed TGM are most likely coming from coal fired power plants, smelters and industrial sources, based on its high correlation with NO x , SO 2 , CO and wind di-15 rections. 20 the atmosphere (Pirrone et al., 2010)

Temporal trend and sources of speciated atmospheric mercury at Waliguan GAW station, Northwestern China

Atmospheric Chemistry and Physics, 2012

Measurements of speciated atmospheric mercury were conducted at a remote mountaintop station (WLG) at the edge of northeastern part of the Qinghai-Xizang Plateau, western China. Mean concentrations of total gaseous mercury (TGM), particulate mercury (PHg), and reactive gaseous mercury (RGM) during the whole sampling campaign were 1.98 ± 0.98 ng m −3 , 19.4 ± 18.1 pg m −3 , and 7.4 ± 4.8 pg m −3 , respectively. Levels of speciated Hg at WLG were slightly higher than those reported from remote areas of North America and Europe. Both regional emissions and long-rang transport played a remarkable role in the distribution of TGM and PHg in ambient air at WLG, whereas RGM showed major links to the regional sources, likely as well as the in-situ productions by photochemical processes. Regional sources for speciated Hg were mostly located to the east of WLG, which is the most developed areas of Qinghai province and accounted for most of the province's anthropogenic Hg emissions. Potential source contribution function (PSCF) results showed a strong impact of long-range transport from eastern Gansu, western Ningxia and Shanxi Province, with good accordance with locations of urban areas and industrial centers. Moreover, we found that northern India was also an important source region of WLG during the sampling campaign, and this is the first time of direct evidence of long-range transport of atmospheric Hg from India to northeastern Tibetan Plateau. Seasonal and diurnal variations of TGM were in contrast with most of the previous studies in China, with relatively higher levels in warm seasons and night, respectively. The temporal trend of TGM also highlighted the impact of long-range transport on the distribution of TGM in ambient air at WLG. 1 Introduction Mercury (Hg) is a highly toxic and persistent pollutant of global environment concern. There are three major operationally-defined forms of Hg in the atmospheric: gaseous elemental mercury (GEM), reactive gaseous mercury (RGM), and particulate mercury 30054