Particle-bound Mercury Concentrations Research Articles

Atmospheric mercury species at Nam Co (4730m a.s.l.), a highland background site in the inland Tibetan Plateau: implications of mercury potential sources.

A field survey was conducted in the central Tibetan Plateau (Nam Co) in China for high-time resolution measurements of gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particle-bound mercury (PBM). Average concentrations (± 1 SD) of GEM, PBM, and GOM from November 2014 to March 2015 were 1.11 ± 0.20ngm-3, 50.8 ± 26.5pgm-3, and 3.6 ± 3.2pgm-3, respectively. During the monitoring period, both GEM and GOM exhibited relative stability in their monthly variations, whereas PBM concentrations were significantly higher in winter compared to those in later autumn and early spring. In terms of diurnal variations, the maximum concentration of GEM was typically observed after sunrise, while PBM reached its peak before sunrise, and the highest concentration of GOM was recorded in the afternoon. Vertical convection conditions, photochemical production, and gas-particle partitioning were responsible for the diurnal cycle of atmospheric mercury. Based on modeling results, it was determined that the air mass transported from South Asia significantly impacted atmospheric mercury levels at Nam Co Station. The regions of western and central Nepal, central and eastern Pakistan, and northern India were identified as potential sources of atmospheric mercury at Nam Co.

Improving Simulation of Gas‐Particle Partitioning of Atmospheric Mercury Using CMAQ‐newHg‐Br v2

AbstractMercury (Hg) is a global pollutant whose atmospheric deposition is a major input to the terrestrial and oceanic ecosystems. Gas‐particle partitioning (GPP) of gaseous oxidized mercury (GOM) redistributes speciated Hg between gas and particulate phase and can subsequently alter Hg deposition flux. Most 3‐dimensional chemical transport models either neglected the Hg GPP process or parameterized it with measurement data limited in time and space. In this study, CMAQ‐newHg‐Br (Ye et al., 2018, https://doi.org/10.1002/2017ms001161) was updated to CMAQ‐newHg‐Br v2 by implementing a new GPP scheme and the most up‐to‐date Hg redox chemistry and was run for the northeastern United States over January‐November 2010. CMAQ‐newHg‐Br v2 reproduced the measured spatiotemporal distributions of gaseous elemental mercury (GEM) and particulate bound mercury (PBM) concentrations and Hg wet deposition flux within reasonable ranges and simulated dry deposition flux in agreement with previous studies. The GPP scheme improved the simulation of PBM via increasing winter‐, spring‐ and fall‐time PBM concentrations by threefold. It also improved simulated Hg wet deposition flux with an increase of 2.1 ± 0.7 μgm2 in the 11‐month accumulated amount, offsetting half of the decreasing effect of the updated chemistry (−4.2 ± 1.8 μgm2). Further, the GPP scheme captured the observed Kp‐T relationship as reported in previous studies without using measurement data and showed advantages at night and in rural/remote areas where existing empirical parameterizations failed. Our study demonstrated CMAQ‐newHg‐Br v2 a promising assessment tool to quantify impacts of climate change and emission reduction policy on Hg cycling.

Characteristics, sources, and health risk assessment of atmospheric particulate mercury in Guanzhong Basin

Mercury (Hg) has received increasing public attention owing to its high toxicity and global distribution capability via long-range atmospheric transportation. Guanzhong Basin (GB) is vital for the industrial and economic development of Shaanxi Province. To determine the concentration, spatial distribution, seasonal variation, sources, and health risks of particulate-bound mercury (PBM), PM2.5 samples were collected at three sampling sites representing urban, rural, and remote areas during winter and summer in GB. The three sampling sites were in Xi'an (XN), Taibai (TB), and the Qinling Mountains (QL). The mean PBM concentrations in XN, TB, and QL in winter were 130 ± 115 pg m−3, 57.5 ± 47.3 pg m−3, and 53.6 ± 38.5 pg m−3, respectively, higher than in summer (13.7 ± 7.11 pg m−3, 8.01 ± 2.86 pg m−3, and 7.75 ± 2.85 pg m−3, respectively). PBM concentrations are affected by precipitation, meteorological conditions (temperature and mixed boundary layer), emission sources, and atmospheric transport. During the sampling period, the PBM dry deposition in XN, TB, and QL was 1.90 μg m−2 (2 months), 0.835 μg m−2 (2 months), and 0.787 μg m−2 (2 months), respectively, lower than the range reported in national megacities. According to backward trajectory and potential source contribution factor (PSCF) analysis, mercury pollution in XN is mainly affected by local pollution source emissions, whereas the polluted air mass in TB and QL originates from local anthropogenic emissions and long-distance atmospheric transmission. The non-carcinogenic health risk values of PBM in XN, TB, and QL in winter and summer were less than 1, indicating that the risk of atmospheric PBM to the health of the residents was negligible.

Atmospheric mercury in a developed region of eastern China: Interannual variation and gas-particle partitioning

Atmospheric mercury plays a crucial role in the biogeochemical cycle of mercury. This study conducted an intensive measurement of atmospheric mercury from 2015 to 2018 at a regional site in eastern China. During this period, the concentration of particle-bound mercury (PBM) decreased by 13%, which was much lower than those of gaseous elemenral mercury (GEM, 30%) and reactive gaseous mercury (GOM, 62%). The gradual decrease in the correlation between PBM and CO, K, and Pb indicates that the influence of primary emissions on PBM concentration was weakening. Moreover, the value of the partitioning coefficient (Kp) increased gradually from 0.05 ± 0.076 m3/μg in 2015 to 0.16 ± 0.37 m3/μg in 2018, indicating that GOM was increasingly inclined to adsorb onto particulate matter. Excluding the influence of meteorological conditions and the primary emissions, the change in aerosol composition is designated as the main trigger factor for the increasing gas-particle partitioning of reactive mercury (RM). The increasing ratio of Cl−, NO3−, and organics (Org) in the chemical composition of particle matters (PM2.5), as well as the decrease in the proportion of SO42−, NH4+, and K+, are conducive to the adsorption of GOM onto particles, forming PBM, which led to an increase of Kp and a lag of PBM reduction compared to GEM and GOM under the continuous control measures of anthropogenic mercury emissions. The evolution of aerosol compositions in recent years affects the migration and transformation of atmospheric mercury, which in turn can affect the biogeochemical cycle of mercury.

Determining sources of reactive mercury compounds in Reno, Nevada, United States

There is much uncertainty regarding the sources of reactive mercury (RM) compounds and atmospheric chemistry driving their formation. This work focused on assessing the chemistry and potential sources of reactive mercury measured in Reno, Nevada, United States, using 1 year of data collected using Reactive Mercury Active System. In addition, ancillary meteorology and criteria air pollutant data, Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) analyses, and a generalized linear model were applied to better understand reactive mercury observations. During the year of sampling, a fire event impacted the sampling site, and gaseous elemental Hg and particulate-bound mercury concentrations increased, as did HgII-S compounds. Data collected on a peak above Reno showed that reactive mercury concentrations were higher at higher elevation, and compounds found in Reno were the same as those measured on the peak. HYSPLIT results demonstrated RM compounds were generated inside and outside of the basin housing Reno. Compounds were sourced from San Francisco, Sacramento, and Reno in the fall and winter, and from long-range transport and the marine boundary layer during the spring and summer. The generalized linear model produced correlations that could be explained; however, when applying the model to similar data collected at two other locations, the Reno model did not predict the observations, suggesting that sampling location chemistry and concentration cannot be generalized.

Atmospheric wet deposition of mercury in urban Jinan, eastern China: Speciation, scavenging process and potential sources

Understanding the speciation and related influence factors of Hg in wet deposition is important to predict the fate and transport of mercury in the atmosphere. In this study, event-based samples of rainwater were collected for one year in Jinan, a northern city in eastern China. The volume-weighted mean concentration of total mercury (THg) in rainwater was 34.8 ng L−1, comparable to levels in some inland cities in China and were significantly higher than those in North America, Korea and Japan. Most of the Hg in rainwater was associated with particulates, accounted for 15.2–92.9% of THg with a mean of 66.9%, which might be attributed to the scavenging effects of high particulate-bound mercury concentrations in ambient air in urban Jinan. Dissolved mercury (DHg) accounted for 33.1% of THg, in which Hg(OH)2, HgClOH, HgCl2 and Hg(NH3)22+ are the dominant species based on the chemical equilibrium modeling simulations. THg concentrations in rainwater decreased as the rainfall amount increased owing to the dilution effect and 5 mm rainfall might be a threshold for the full wash-out capability of atmospheric Hg. For a continuous rain event, the proportion of DHg in THg could increase from 7.1% to 84.8% with the rainfall processing, especially for the species of HgClOH and HgCl2 under the influence of rainwater pH. Positive matrix factorization (PMF) analysis suggested that the major sources of Hg in rainwater were combustion emissions, marine sources, industrial emissions, as well as complexation process, which contributed to 51.4%, 24.7%, 12.2%, and 11.7% of the THg, respectively. For the specific species, the main sources varied with different Hg species, in which combustion emissions contributed one third to one half of each species sum to particulate mercury (PHg), HgClOH, HgCl2, HgBrOH and HgBrCl followed by marine sources and industrial emissions. Cluster analysis of backward trajectories revealed that polluted air masses, transported from southeast Shandong, Anhui and Jiangsu Provinces, as well as Beijing-Tianjin-Hebei region, contributed to high Hg concentration in rainwater in Jinan.

Spatial variations of particulate-bound mercury in the atmosphere along a transect from the mid-Northern Hemisphere to the high southern latitudes

Particulate-bound mercury (PBM) measurements in the boundary layer were performed during the 2015–2016 Chinese Antarctic Research Expedition from the middle Northern Hemisphere (Shanghai, China) to the Antarctic Ice Sheet summit, Dome A. A significant latitudinal gradient in PBM was observed. PBM over the Northern Hemisphere oceans was influenced by both continental and oceanic sources, with elevated PBM levels associated with continental inputs. PBM over this region was significantly higher in November than that in April, which could be related to the continental Hg carried by the strong East Asian winter monsoon. Far away from the continental sources, extremely low PBM was observed over the Southern Ocean (2.6 ± 1.6 pg m−3). Elevated PBM was found across the Antarctic Ice Sheet (79.1 ± 43.4 pg m−3), and the highest PBM observed at Dome A (143.4 ± 27.0 pg m−3) was likely associated with GEM emissions from snow and enhanced oxidation of GEM due to snow photochemistry. Across the Antarctic Ice Sheet, PBM increased significantly with the increasing distance from the coast, which may have resulted from the mixing of air masses from the Antarctic plateau and the ocean. GEM emissions from inland Antarctic snow can influence atmospheric PBM concentrations over the Antarctic coastal seas via the transport by katabatic winds, and thus play an important role in atmospheric Hg cycle in the high southern latitudes.

Atmospheric particulate-bound mercury (PBM10) in a Southeast Asia megacity: Sources and health risk assessment

Particulate-bound mercury (PBM) is a global environmental concern owing to its large dry deposition velocities and scavenging coefficients, both of which drive Hg into terrestrial and marine ecosystems. PBM observation studies have been widely conducted over East Asia, but comparable studies in Peninsular Southeast Asia (PSEA) remain scarce. This is the first study reporting PBM concentrations for Ho Chi Minh City (HCMC), the biggest metropolitan area in Vietnam. A total of 222 samples were collected in 2018 and contained an average PBM10 (particulate matter – PM with diameter ≤10 μm) concentration and Hg mass fraction (i.e. PBM/PM) of 67.3 ± 45.9 pg m−3 and 1.18 ± 1.12 μg g−1, respectively. Although PBM concentration was lower than those reported in Chinese megacities, the Hg mass fraction was similar to those in China, suggesting strong enrichment from anthropogenic Hg emissions in HCMC. Traffic-induced particulate emission and deposition processes were major factors governing PBM temporal variation at our site. In addition, the prevailing southwest monsoon winds brought air masses that passed through industrial areas and were associated with a higher Hg mass fraction. Statistically significant positive correlations (R2 = 0.11–0.52, p < 0.01) were observed for PBM with PM and the Hg mass fraction, indicating similar PM and Hg sources or oxidized Hg adsorption onto PM via gas-particle partitioning. Moreover, PCA results revealed a higher contribution of primary sources than secondary sources to PBM concentration variability in HCMC. A health risk assessment indicated that the PBM concentrations at HCMC posed minimal non-carcinogenic risks (HI < 1) for children and adults, but dermal contact may act as an important exposure route since lightweight clothing is common among residents. This PBM dataset over PSEA, a region with high atmospheric Hg emissions, provides a valuable resource for the Hg scientific community to improve our understanding of Hg biogeochemical cycle.

Long-range transport of La Soufrière volcanic plume to the western North Pacific: Influence on atmospheric mercury and aerosol properties

Volcanic eruptions are important natural sources of gases and aerosols to the environment. However, their impact on the global cycle of trace elements, including mercury (Hg), remains poorly understood. On 9 April 2021, La Soufrière volcano (13.33°N, 61.18°W) erupted in the Caribbean Sea. Ozone Monitoring Instrument (OMI) measurements of sulfur dioxide (SO2) tracked the transport of volcanic SO2 in the troposphere over long distances from the source, including to the western North Pacific ∼10 day after eruption. A spike in gaseous and particle-bound mercury concentrations along with a peak in aerosol back-scattering coefficient at Lulin Atmospheric Background Station (LABS, 23.47°N, 120.87°E; 2862 m AMSL) coincided with the volcanic plume transport on 19 April. The slope of gaseous elemental mercury vs. carbon monoxide concentrations during the event was 0.027, which is distinctly higher than for Southeast Asia biomass burning (slope = 0.005) and East Asia outflow (0.011) pollution sources. Arrival of the plume high above Taiwan was confirmed by significant changes in signature aerosol properties. Thus, with critical observational evidence, our study reported for the first time enhanced mercury levels ∼18000 km downwind from a volcano source, providing an important check on volcanic Hg emission strength.

Particulate and particulate-bound mercury concentrations and size distributions as related to seasonal variations during peak demand/non-peak demand periods

The particulate size distributions of aerosol pollutants (particulates and Hg(p)) at a mixed site were measured and their seasonal variations identified. Atmospheric particulates and the Hg(p) mass median diameter (m.m.d.) were obtained. Hg(p) concentrations increased by approximately 20% during the peak demand period for all particle sizes (18, 10, 2.5, 1 and 0.3 μm). The mean percentage concentration of Hg(p) was highest in summer and followed the order summer > spring > winter > autumn for all particle sizes. Hg(p) concentration exhibited increased from 2004 to 2019.

Variation in the mercury concentration and stable isotope composition of atmospheric total suspended particles in Beijing, China

We investigated the effect of the temporary ban of local industrial activities during the Asia-Pacific Economic Cooperation (APEC) summit (4th–14th Nov 2014) in Beijing, China on total suspended particulate mercury (HgTSP) concentrations and isotope compositions. We measured Hg concentrations and isotope ratios in 33 TSP samples from central Beijing, including 21 samples collected from Jun 2012 to Apr 2014, and 12 samples collected from 14th Oct–19th Nov 2014. Volumetric concentrations of both TSP and HgTSP during the APEC summit were a factor of 2 lower than during the pre-APEC period, indicating substantial reductions in total particulate matter and HgTSP as a result of emissions controls. However, mass-normalized concentrations and mercury isotope ratios of HgTSP did not vary significantly between samples collected before, during, or after the APEC summit. These results show that local emissions are important sources of particle bound mercury (PBM) in Beijing and that their control can be used to immediately lower the volumetric concentration of HgTSP. They also indicate that a similarly complex mixture of sources contributed to PBM in Beijing before and during emissions controls were put in place and that PBM concentrations in Beijing are primarily controlled by emissions and secondarily by photoreduction.

Measurements and Distribution of Atmospheric Particulate-Bound Mercury: A Review.

Atmospheric particulate-bound mercury (PBM) plays an important role in the geochemical cycling of mercury (Hg). This study reviewed research progress of the PBM, including the possible emission and deposition pathways, measurement methods and the global distribution. The primary PBM sources are anthropogenic sources, but natural sources could be also a considerable contributor, for instance, chemical transport and dust in the arid and desert area. Different filter methods, such as quartz fibre filters, have been applied to the PBM measurement, and PBM can also be real-time monitored automatically. Generally, the average PBM concentrations were higher in the Northern Hemisphere than in the Southern Hemisphere. However, the PBM level of Antarctica is quite high. PBM concentrations were higher in the urban areas than in the remote areas, and there was a high PBM level in the developing countries. Moreover, high PBM concentrations were observed in the range 20°-60° of northern latitude.

Measurement of size-fractionated particulate-bound mercury in Beijing and implications on sources and dry deposition of mercury

Particulate-bound mercury (PBM) plays an important role in the Hg cycling and is with high concentration in urban area. Totally 10-staged (range of 0.01–10μm) size-fractionated PBM was measured in Beijing during December 2016–November 2017. Our study indicated that Beijing suffered from heavy PBM pollution, with an annual average of 297.9 (17.2–1906.6) pgm−3, 22.2–52.5 times higher than that observed in North America. Overall, the concentration of PBM2.5 (PBM2.5 and PBM2.5–10 meant PBM concentration in PM with aerodynamic diameter <2.5μm and in the range of 2.5–10μm, respectively) accounted for 75%–87% of PBM10 in all seasons. The increase of PBM2.5–10 in the polluted days (PM2.5>75μgm−3) indicated the primary influence from natural sources while anthropogenic sources and secondary conversion caused the growth of PBM2.5 concentration. In addition, the generation of secondary PBM during the transport process contributed to the generation of PBM in Beijing, especially when the PM concentrations increase simultaneously. The local emissions and physicochemical conversion were the dominant cause of extremely high PBM pollution event in winter. Enhanced PBM concentrations also lead to severe dry deposition of PBM in Beijing. The estimated annual dry deposition of PBM was 40.6μgm−2yr−1, which was 3.1–203.0 times than observations from other sites in northern hemisphere. PBM2.5 contributed 53% of total dry deposition in all seasons, significantly higher than the other observation sites (28%–36%). In addition, the proportion of PBM2.5 deposition in PBM10 deposition ranged from 47% in summer to 66% in winter, which indicated that both seasonal variations of PBM size distribution characteristics should be taken into consideration. Results from this study revealed the size distribution and dry deposition characteristics of PBM in urban Beijing and provided base for the implementation of Minamata convention on mercury.

Concentrations and gas-particle partitioning of atmospheric reactive mercury at an urban site in Beijing, China

Measurements of speciated atmospheric mercury play a key role in identifying mercury behavior in the atmosphere. In this study, we measured speciated atmospheric mercury, including gaseous elemental mercury (GEM), reactive gaseous mercury (RGM), and particulate bound mercury (PBM) (<2.5 μm), in 2015 and 2016 at an urban site in Beijing, China. The mean concentrations of GEM, RGM, and PBM were 4.70 ± 3.53 ng m−3, 18.47 ± 22.27 pg m−3, and 85.18 ± 95.34 pg m−3, respectively. The concentration of PM2.5 significantly affected the distribution of reactive mercury between the gaseous and particulate phases. With the raising of PM2.5 levels, PBM concentrations increased, on the contrary, the concentrations of RGM decreased gradually. The mean concentration of PBM during air-pollution events was more than three times that during clear days. During days with air pollution, the relative humidity significantly affected the gas-particle partitioning of reactive mercury. The linear relationships between gas-particle partitioning coefficient and meteorological factors (air temperature and relative humidity) were obtained over the four seasons. The data also showed that the gas-particle partitioning coefficient of reactive mercury was related to particle composition (e.g., Cl−, BC). The data present in this paper suggested the influence of anthropogenic emissions on reactive mercury in Beijing urban. And the findings will contribute to understand the gas-particle partitioning of reactive mercury and its influencing factors with complex urban pollution.

First measurement of atmospheric mercury species in Qomolangma Natural Nature Preserve, Tibetan Plateau, and evidence oftransboundary pollutant invasion

Abstract. Located in the world's “third pole” and a remote region connecting the Indian plate and the Eurasian plate, Qomolangma National Nature Preserve (QNNP) is an ideal region to study the long-range transport of atmospheric pollutants. In this study, gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM) and particle-bound mercury (PBM) were continuously measured during the Indian monsoon transition period in QNNP. A slight increase in the GEM concentration was observed from the period preceding the Indian summer monsoon (1.31±0.42 ng m−3) to the Indian summer monsoon period (1.44±0.36 ng m−3), while significant decreases were observed in the GOM and PBM concentrations, with concentrations decreasing from 35.2±18.6 to 19.3±10.9 pg m−3 (p &lt; 0.001) for GOM and from 30.5±12.5 to 24.9±19.8 pg m−3 (p &lt; 0.001) for PBM. A unique daily pattern was observed in QNNP with respect to the GEM concentration, with a peak value before sunrise and a low value at noon. Relative to the (low) GEM concentrations, GOM concentrations (with a mean value of 21.4±13.4 pg m−3, n=1239) in this region were relatively high compared with the measured values in some other regions of China. A cluster analysis indicated that the air masses transported to QNNP changed significantly at different stages of the monsoon, and the major potential mercury (Hg) sources shifted from northern India and western Nepal to eastern Nepal and Bangladesh. As there is a large area covered in glaciers in QNNP, local glacier winds could increase the transboundary transport of pollutants and transport polluted air masses to the Tibetan Plateau. The atmospheric Hg concentration in QNNP in the Indian summer monsoon period was influenced by transboundary Hg flows. This highlights the need for a more specific identification of Hg sources impacting QNNP and underscores the importance of international cooperation regarding global Hg controls.

Investigate the impact of local iron-steel industrial emission on atmospheric mercury concentration in Yangtze River Delta, China.

Mercury is a global neurotoxic pollutant, which can be globally transported and bioaccumulated in the food chain. Iron-steel production is one of the most significant sources of anthropogenic atmospheric mercury emission, while information on this source is scarce. Hourly gaseous elemental mercury (GEM) and particle bound mercury (PBM) were studied inside (IP) and at the boundary (BP) of a typical iron-steel plant in the Yangtze River Delta (YRD), China from September 2016 to August 2017. The GEM concentrations were 0.97-503.1 and 0.05-112.6ng/m3 at the IP and BP sites, respectively, while PBM concentrations were one to four orders of magnitude higher than urban and suburban ambient levels. Several lines of evidences indicated that PBM was mainly originated from the iron-steel manufacturing process, especially from sintering and coke-making processes in this iron-steel plant. However, a combined emission effect contributed to GEM variation. The receptor model of positive matrix factorization (PMF) showed that local direct emissions (coal combustion, industrial activity, vehicle exhaust, and secondary evaporation from polluted soil) contributed 51.3% of the total GEM concentration variation. Potential source contribution function (PSCF) and concentration weighted trajectory (CWT) models clearly showed that air masses moving from areas surrounding YRD had the highest concentrations of atmospheric mercury. These results provided evidence that iron-steel manufacturing emissions have a considerable effect on regional atmospheric mercury concentrations, especially PBM.

Characteristics of particulate-bound mercury at typical sites situated on dust transport paths in China

The concentrations and seasonal variations of PBM (particulate-bound mercury) were observed at four dust source sites (Duolun, Yulin, Hetian, and Tazhong), two megacities (Shanghai and Beijing), and an island site (Huaniao Island) to obtain the spatiotemporal characteristics of PBM in dust transport path from desert area in China to the East China Sea. The highest annual mean concentrations of PBM in TSP (PBMTSP) were observed at megacity sites, reaching 146.7 pg/m3 and 274.7 pg/m3 in Shanghai and Beijing attributed primarily to anthropogenic emissions, while 39.7 pg/m3, 67.3 pg/m3, 61.0 pg/m3, 23.5 pg/m3 and 43.6 pg/m3 over Duolun, Yulin, Hetian, Tazhong, and Huaniao Island, respectively. PBM concentrations were higher in winter and autumn, while lower in spring and summer due to the variation of meteorological conditions (especially temperature and wind speed) together with the emission sources. Enrichment factors (EFs) of PBMTSP and PBM2.5 reached 158 and 1452 in Beijing, showing the serious anthropogenic emissions impacted on PBM pollution in megacities, and the profound high level of EFs of mercury in sand dust source sites (17–64 for TSP and 38–252 for PM2.5), suggesting the obvious mixing effect of dust and anthropogenic aerosols in dust source areas. Human activities played a major role in the increase of PBM concentrations and the enrichment factors during the long-range transport of air mass in China. The significant anthropogenic mercury emissions in the dust source areas and their long-range transport driven by the East Asian Monsoon might impact on the ecological cycle of mercury and should be taken into the mercury inventories. Coal combustion and smelting contributed 52–94% to PBM over all three types of sampling sites, and mining operations were additional sources of PBM in Yulin. In the coastal area, sea salt is an important source of PBM, and shipping could also contribute a certain proportion to PBM pollution which shouldn't be ignored.

Distribution of gaseous and particle-bound Hg concentrations at the sites representative for urban and non-urban zones of Silesia Province

The basic features of the distribution of total gaseous (TGM) and particle-bound mercury (PBM) concentrations were determined for a five locations representative for urban (Bielsko-Biała, Lubliniec, Zabrze) and rural areas (Godów, Złoty Potok) of Silesia Province. Gaseous mercury concentrations were measured (1) continuously - the automatic 1h TGM measurements in Zloty Potok and Zabrze and (2) non-continuously manual 24h TGM measurements with a pre-concentration of the Hg on gold traps (Bielsko-Biała, Lubliniec, Godów). The PBM concentrations were measured non-continuously by taking PM2.5 samples. The Hg content was determined by using a CVAAS method. The highest average concentration of TGM was recorded in Zabrze (2.8ng/m3), significantly lower (2.0ng/m3) in Bielsko-Biała and in the non-urban station in Godów, the lowest concentration (&lt;2.0 ng/m3) was observed in Lubliniec and at the regional background station in Zloty Potok. The results obtained for TGM concentrations exceeded the European average level of 1.5 ng/m3 (AirBase, 2014). The highest average PBM concentration, associated with PM2.5, was obtained in Zabrze (70pg/m3), more than 20% lower results were obtained in Bielsko-Biała and Godów, finally, the lowest one (lower by about 40% in comparison with Zabrze) were obtained in Lubliniec and Złoty Potok. Moreover, an enrichment of Hg concentration in PM was observed with the increasing of the PM content, during the heating season.

Seasonal variations of ambient air mercury species nearby an airport

This study focuses on the collection of ambient air mercury species (total gaseous mercury (TGM), reactive gaseous mercury (RGM), gaseous element mercury (GEM) and particulate bound mercury (PBM) pollutants at airport nearby sampling site during the year of Apr. 2016 to Mar. 2017 by using Four-stage gold amalgamation and denuder. The results indicated that the average TGM, RGM and GEM concentrations were 5.04±2.43ng/m3, 29.58±80.54pg/m3, 4.70±2.63ng/m3, respectively during the year of Apr. 2016 to Mar. 2017 (n=49) period at this airport sampling site nearby. In addition, the results also indicated that the average PBM concentrations in TSP and PM2.5 were 0.35±0.08ng/m3 and 0.09±0.03ng/m3, respectively. And the average PBM in TSP concentrations order follows as summer>autumn>spring>winter, while the average PBM in PM2.5 concentrations order follows as spring>summer>winter>autumn. Moreover, the average TGM, RGM and GEM concentrations order follow as spring>summer>autumn>winter. Finally, the Asian continent has the highest average mercury species concentrations (TGM, RGM, GEM and PBM) when compared with the American and European continents, and the average mercury species concentrations (TGM, RGM, GEM and PBM) displayed declined trends for North America (United States and Canada) and Europe (Spain, Sweden and Southern Baltic) during the years of 2004–2014. Also noteworthy is that the average mercury species concentrations (TGM, RGM, GEM) displayed increasing trends in China and Taiwan during the years of 2008–2016. Japan and Korea are the only two exceptions. Those above two countries mercury species concentrations displayed decreasing trends during years of 2008–2015.

Atmospheric Mercury Temporal Trends in the Northeastern United States from 1992 to 2014: Are Measured Concentrations Responding to Decreasing Regional Emissions?

Long-term atmospheric mercury measurements at Underhill, VT (VT99), and Huntington Forest, NY (NY20), from 1992 to 2014 and 2005 to 2014, respectively, were used to determine concentration trends using Mann–Kendall’s tau test with Sen’s slope estimator. These data, measured generally downwind of large Hg sources in the Midwestern United States, provide the longest record of ambient Hg concentrations available in the United States. At VT99, concentrations of gaseous element mercury (GEM), gaseous oxidized mercury (GOM), and particle-bound mercury (PBM) declined at rates of −1.8, −3.2, and −6.7%/year, respectively. At NY20, GEM and GOM concentrations declined at rates of −1.6 and −7.8%/year, respectively; however, PBM concentrations increased at a rate of 2.0%/year, which is likely related to winter wood burning. A trajectory ensemble analysis using the potential source contribution function indicates the source locations associated with high mercury concentrations changed from Toronto–Buffalo and Pennsylva...