Characteristics and potential sources of atmospheric mercury at a subtropical near‐coastal site in East China

Abstract. The contribution from different emission sources and atmospheric processes to gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), particulate bound mercury (PBM) and mercury deposition in East China were quantified using the Community Multi-scale Air Quality (CMAQ-Hg) modeling system run with nested grid resolution of 27 km. Natural source (NAT) and six categories of anthropogenic mercury sources (ANTH) including cement production (CEM), domestic life (DOM), industrial boilers (IND), metal production (MET), coal-fired power plants (PP) and traffic (TRA) were considered for source apportionment. NAT was responsible for 36.6% of annual averaged GEM concentration which was regard as the most important source for GEM in spite of obvious seasonal variation. Among ANTH, the influence of MET and PP on GEM were most evident especially in winter. ANTH dominated the variations of GOM and PBM concentration with a contribution of 86.7 and 79.1% respectively. Among ANTH, IND was the largest contributor for GOM (57.5%) and PBM (34.4%) so that most mercury deposition came from IND. The effect of mercury emitted from out of China was indicated by > 30% contribution to GEM concentration and wet deposition. The contribution from nine processes consisting of emissions (EMIS), gas-phase chemical production/loss (CHEM), horizontal advection (HADV), vertical advection (ZADV), horizontal advection (HDIF), vertical diffusion (VDIF), dry deposition (DDEP), cloud processes (CLDS) and aerosol processes (AERO) were calculated for processes analysis with their comparison in urban and non-urban regions of Yangtze River Delta (YRD). EMIS and VDIF affected surface GEM and PBM concentration most and tended to compensate each other all the time in both urban and non-urban areas. However, DDEP was the most important removal process for GOM with 7.3 and 2.9 ng m−3 reduced in the surface of urban and non-urban areas respectively in a whole day. Diurnal profile variation of processes revealed the transportation of GOM from urban area to non-urban area and the importance of CHEM/AERO in higher altitudes which caused diffusion of GOM downwards to non-urban area partly. Most of the anthropogenic mercury transported and diffused away from urban area by HADV and VDIF and made gain of mercury in non-urban areas by HADV. Natural emissions only influenced CHEM and AERO more significantly than anthropogenic. Local emission in the YRD contributed 8.5% more to GEM and ~ 30% more to GOM and PBM in urban areas compared to non-urban areas.

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Interactive comment on “Characteristics of atmospheric mercury in East China: implication on sources and formation of mercury species over a regional transport intersection zone” by Q. Yu et al.

10.5194/acp-2018-1164-rc1 ◽

2018 ◽

Author(s):

Anonymous

Keyword(s):

Atmospheric Mercury ◽

East China ◽

Mercury Species ◽

Regional Transport

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Recent decrease trend of atmospheric mercury concentrations in East China: the influence of anthropogenic emissions

10.5194/acp-2017-1203 ◽

2018 ◽

Author(s):

Yi Tang ◽

Shuxiao Wang ◽

Qingru Wu ◽

Kaiyun Liu ◽

Long Wang ◽

...

Keyword(s):

Air Pollutants ◽

Sampling Period ◽

Atmospheric Mercury ◽

Meteorological Conditions ◽

East China ◽

Anthropogenic Emissions ◽

Chongming Island

Abstract. Measurements of gaseous elemental Hg (GEM), other air pollutants including SO2, NOx, O3, PM2.5, CO, and meteorological conditions were carried out at Chongming Island in East China from March 1 in 2014 to December 31 in 2016. During the sampling period, GEM concentrations significantly decreased from 2.68 ± 1.07 ng m−3 in 2014 to 1.60 ± 0.56 ng m−3 in 2016. Monthly mean GEM concentrations showed a significant decrease with a rate of −0.60 ng m−3 yr−1 (R2 = 0.6389, p

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Sources of atmospheric mercury in the tropics: continuous observations at a coastal site in Suriname

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-10223-2012 ◽

2012 ◽

Vol 12 (4) ◽

pp. 10223-10242 ◽

Cited By ~ 1

Author(s):

D. Müller ◽

D. Wip ◽

T. Warneke ◽

C. D. Holmes ◽

A. Dastoor ◽

...

Keyword(s):

Atlantic Ocean ◽

Northern Hemisphere ◽

Seasonal Cycle ◽

Atmospheric Mercury ◽

South American ◽

The South ◽

Coastal Site ◽

Back Trajectories ◽

The Tropics ◽

Marine Air

Abstract. Mercury measurements at a coastal site in Nieuw Nickerie (5°56' N, 56°59' W), Suriname, provide the only continuous records of atmospheric mercury in the tropics. Here we evaluate observations of total gaseous mercury (TGM) during 2007. Nieuw Nickerie typically samples marine air from the Atlantic Ocean, with occasional influence from continental South America. Over the year, average concentrations are 1.40 ng m−3. As the intertropical convergence zone passes over Suriname twice each year, the site samples both northern and southern hemispheric air masses. We use back trajectories to classify each measurement by hemisphere, as well as continental or ocean. For air passing over ocean before sampling, TGM concentrations are 10% higher in air coming from the Northern Hemisphere (1.45 ng m−3) than from the Southern Hemisphere (1.32 ng m−3). Air from the South American continent also carries higher TGM (1.43 ng m−3) than air from the South Atlantic Ocean, with most of these trajectories occurring in August and September. Biomass burning in Brazil peaks in the same months and likely contributes significantly to elevated concentrations seen in Nickerie. We also compare the observed seasonal cycle to two atmospheric mercury chemistry and transport models (GRAHM and GEOS-Chem). Both models simulate transition between northern and southern hemispheric air, thus capturing the seasonal cycle; however the models overestimate the TGM concentrations during months when Nickerie samples Northern Hemisphere air. It is difficult to determine whether the models' sources or sinks in the Northern Hemisphere tropics are responsible.

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Sources of atmospheric mercury in the tropics: continuous observations at a coastal site in Suriname

Atmospheric Chemistry and Physics ◽

10.5194/acp-12-7391-2012 ◽

2012 ◽

Vol 12 (16) ◽

pp. 7391-7397 ◽

Cited By ~ 24

Author(s):

D. Müller ◽

D. Wip ◽

T. Warneke ◽

C. D. Holmes ◽

A. Dastoor ◽

...

Keyword(s):

Atlantic Ocean ◽

Northern Hemisphere ◽

Seasonal Cycle ◽

Atmospheric Mercury ◽

South American ◽

The South ◽

Coastal Site ◽

Back Trajectories ◽

The Tropics ◽

Marine Air

Abstract. Mercury measurements at a coastal site in Nieuw Nickerie (5°56' N, 56°59' W), Suriname, provide the only continuous records of atmospheric mercury in the tropics. Here we evaluate observations of total gaseous mercury (TGM) during 2007. Nieuw Nickerie typically samples marine air from the Atlantic Ocean, with occasional influence from continental South America. Over the year, average concentrations are 1.40 ng m−3. As the intertropical convergence zone passes over Suriname twice each year, the site samples both northern and southern hemispheric air masses. We use back trajectories to classify each measurement by hemisphere, as well as continental or ocean. For air passing over ocean before sampling, TGM concentrations are 10% higher in air coming from the Northern Hemisphere (1.45 ng m−3) than from the Southern Hemisphere (1.32 ng m−3). Air from the South American continent also carries higher TGM (1.43 ng m−3) than air from the South Atlantic Ocean, with most of these trajectories occurring in August and September. Biomass burning in Brazil peaks in the same months and likely contributes significantly to elevated concentrations seen in Nickerie. We also compare the observed seasonal cycle to two atmospheric mercury chemistry and transport models (GRAHM and GEOS-Chem). Both models simulate transition between northern and southern hemispheric air, thus capturing the seasonal cycle; however the models overestimate the TGM concentrations during months when Nickerie samples Northern Hemisphere air. It is difficult to determine whether the models' sources or sinks in the Northern Hemisphere tropics are responsible.

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Characteristics of atmospheric mercury in East China: implication on sources and formation of mercury species over a regional transport intersection zone

10.5194/acp-2018-1164 ◽

2018 ◽

Cited By ~ 1

Author(s):

Xiaofei Qin ◽

Xiaohao Wang ◽

Yijie Shi ◽

Guangyuan Yu ◽

Yanfen Lin ◽

...

Keyword(s):

Long Range ◽

Seasonal Pattern ◽

Source Region ◽

Atmospheric Mercury ◽

Anthropogenic Sources ◽

East China ◽

Long Range Transport ◽

Mercury Species ◽

Regional Transport ◽

Range Transport

Abstract. Mercury (Hg) is a global pollutant of great concern in East Asia, which is considered to be the largest mercury-emitting region in the world. In this study, atmospheric gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particulate-bound mercury (PBM) were measured continuously over a regional transport intersection zone in East China to reveal the sources and formation of mercury species. The annual mean concentrations of GEM, PBM, and GOM reached 2.77 ng/m3, 60.80 pg/m3, and 82.13 pg/m3, respectively. GEM concentrations were elevated in both cold and warm seasons. This seasonal pattern of GEM suggested that the re-emissions from natural surfaces play a significant role in the fluctuation of atmospheric mercury in addition to anthropogenic sources. Relationship between Hg species and wind directions indicated the high Hg concentrations were related to winds from the south, southwest, and north of the measurement site. An application of the GOM/PBM tracer method and trajectory-based source region identification suggested that long-range transport from northern China and quasi-local emissions were the main sources of Hg species. It was revealed that GEM concentrations were higher when quasi-local sources dominated compared to the dominance of long-range transport events. Six sources and their contributions to anthropogenic GEM were identified. Besides the common anthropogenic emission sectors, shipping emission was found to be an important source (19.6 %) of atmospheric mercury in East China, where marine vessel shipping activities are intense. Concurrences of high GOM concentrations with elevated O3 and temperature, along with the lagged variation of GEM and GOM during daytime demonstrated the very high GOM concentrations were ascribed to the intense in situ oxidation of GEM. Statistical analysis showed that when PM2.5 reached a certain value, GOM was inhibited to some extent due to the gas-particle partitioning process. This process was obvious under the conditions of high PM2.5 concentrations, high humidity, and low temperature.

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Concentration-weighted trajectory approach to identifying potential sources of speciated atmospheric mercury at an urban coastal site in Nova Scotia, Canada

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-6031-2013 ◽

2013 ◽

Vol 13 (12) ◽

pp. 6031-6048 ◽

Cited By ~ 69

Author(s):

I. Cheng ◽

L. Zhang ◽

P. Blanchard ◽

J. Dalziel ◽

R. Tordon

Keyword(s):

Nova Scotia ◽

Elemental Mercury ◽

Atmospheric Mercury ◽

Point Sources ◽

Grid Cells ◽

Coastal Site ◽

Northern Ontario ◽

Gaseous Elemental Mercury ◽

Source Areas ◽

Local Sources

Abstract. Regional and local sources contributing to gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particle-bound mercury (PBM) at an urban coastal site in Dartmouth, Nova Scotia, Canada were investigated using the Concentration-Weighted Trajectory model (CWT) and Conditional Probability Function. From 2010–2011, GEM, GOM, and PBM concentrations were 1.67 ± 1.01 ng m−3, 2.07 ± 3.35 pg m−3, and 2.32 ± 3.09 pg m−3, respectively. Seasonal variability was observed, with statistically higher GEM and PBM concentrations in winter and spring and higher GOM in spring. In the CWT, concentrations are the weighting factors for the trajectory residence time in modeled grid cells, which results in the identification of source areas based on the CWT values in the grid cells. Potential source areas were identified in regions with known industrial Hg sources particularly in the fall season, but also in regions without these sources (e.g. Atlantic Ocean, northern Ontario and Quebec). CWTs for GOM and PBM that were associated with ≥ 5 kg industrial Hg emissions from 2010–2011 were statistically larger than those with zero Hg emissions, despite a lack of strong correlations. A large proportion of elevated CWTs (85–97%) was in regions with zero industrial Hg sources indicating the potential role of non-point sources, natural emissions, and residential-scale combustion. Analysis of wind data suggests that a commercial harbor and vehicular traffic were potential local sources. Evaluating modeled source areas against Hg emissions inventories was not an ideal method for assessing the CWT model accuracy because of insufficient data on Hg emissions at more precise locations.

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