Gaseous elemental mercury (GEM) fluxes over canopy of two typical subtropical forests in south China

Yu, Qian; Luo, Yiqi; Wang, Yafei; Wang, Zhiqi; Hao, Jiming; Duan, Lei

doi:10.5194/acp-18-495-2018

Cited by 34 publications

(46 citation statements)

References 78 publications

(101 reference statements)

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“…The increase of O 3 concentration from the summer of 2014 to 2016 may contribute to a higher oxidation of GEM in 2016. On the other hand, higher wet Hg deposition in summer was approximately 6.6 times that in the winter at Chongming (Zhang et al, 2010). Meanwhile, the rainfall in 2016 summer (546 mm) was higher than the rainfall in 2014 (426 mm).…”

Section: Seasonal Variation Of Gem Concentrationsmentioning

confidence: 83%

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

Tang

Wang

et al. 2018

Atmos. Chem. Phys.

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Abstract. Measurements of gaseous elemental mercury (GEM), other air pollutants, including SO2, NOx, O3, PM2.5, and CO, and meteorological conditions were carried out at Chongming Island in East China from 1 March 2014 to 31 December 2016. During the sampling period, GEM concentrations significantly decreased from 2.68 ± 1.07 ng m−3 in 2014 (March to December) to 1.60 ± 0.56 ng m−3 in 2016 (March to December). Monthly mean GEM concentration showed a significant decrease, at a rate of -0.60±0.08 ng m−3 yr−1 (R2=0.64, p < 0.01 significance level). Combining the analysis of the potential source contribution function (PSCF), principle component analysis (PCA), and the emission inventory, we found that the Yangtze River Delta (YRD) region was the dominant source region of GEM in Chongming Island and the main source industries included coal-fired power plants, coal-fired industrial boilers, and cement clinker production. We further quantified the effect of emission change on the air Hg concentration variations at Chongming Island through a coupled method of trajectory clusters and air Hg concentrations. It was found that the reduction of domestic emissions was the main driver of GEM decline in Chongming Island, accounting for 70 % of the total decline. The results indicated that air pollution control policies targeting SO2, NOx, and particulate matter reductions had significant co-benefits on GEM.

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Section: Seasonal Variation Of Gem Concentrationsmentioning

confidence: 83%

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

Tang

Wang

et al. 2018

Atmos. Chem. Phys.

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“…The average GEM dry deposition is lower in Europe (4.3 ± 8.1 µg m −2 yr −1 ) but higher in North America with more variation (5.2 ± 15.5 µg m −2 yr −1 ) (Castelle et al, 2009;Baya and Heyst, 2010;Converse et al, 2010;Miller et al, 2011). The four Asian sites all show negative values, indicating the role of East Asia as a net emission source rather than a net deposition sink (Luo et al, 2016;Ci et al, 2016;Yu et al, 2018). However, the GEM dry deposition observations in Asia are still very limited.…”

Section: ;mentioning

confidence: 96%

“…Most of the RM dry deposition measurements used the surrogate surface methods Wright et al, 2016). The micrometeorological methods and the enclosure methods were also adopted in some studies (Poissant et al, 2004;Zhang et al, 2005;Skov et al, 2006) but not widely used due to the high uncertainties in the measurements of GOM and PBM concentrations using the Tekran system. For the surrogate surface methods, the RM dry deposition flux is determined using the following equation :…”

Section: Measurements Of Rm (Gom and Pbm) Dry Depositionmentioning

confidence: 99%

“…GEM has a low dry deposition velocity due to its mild activity, high volatility, and low water solubility, and deposited GEM could re-emit into the atmosphere (Bullock et al, 2008;Fu et al, 2016b). Various methods have been applied to studies on air-surface GEM exchange, among which the enclosure methods and the micrometeorological methods were most commonly used Agnan et al, 2016;Zhu et al, 2016;Yu et al, 2018). Both Agnan et al (2016) and Zhu et al (2016) have presented comprehensive reviews on air-surface GEM exchange and introduced the two types of methods for measurements.…”

Section: Measurements Of Gem Dry Depositionmentioning

confidence: 99%

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Atmospheric mercury deposition over the land surfaces and the associated uncertainties in observations and simulations: a critical review

et al. 2019

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Abstract. One of the most important processes in the global mercury (Hg) biogeochemical cycling is the deposition of atmospheric Hg, including gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particulate-bound mercury (PBM), to the land surfaces. Results of wet, dry, and forest Hg deposition from global observation networks, individual monitoring studies, and observation-based simulations have been reviewed in this study. Uncertainties in the observation and simulation of global speciated atmospheric Hg deposition to the land surfaces have been systemically estimated based on assessment of commonly used observation methods, campaign results for comparison of different methods, model evaluation with observation data, and sensitivity analysis for model parameterization. The uncertainties of GOM and PBM dry deposition measurements come from the interference of unwanted Hg forms or incomplete capture of targeted Hg forms, while that of GEM dry deposition observation originates from the lack of a standardized experimental system and operating procedure. The large biases in the measurements of GOM and PBM concentrations and the high sensitivities of key parameters in resistance models lead to high uncertainties in GOM and PBM dry deposition simulation. Non-precipitation Hg wet deposition could play a crucial role in alpine and coastal regions, and its high uncertainties in both observation and simulation affect the overall uncertainties of Hg wet deposition. The overall uncertainties in the observation and simulation of the total global Hg deposition were estimated to be ± (25–50) % and ± (45–70) %, respectively, with the largest contributions from dry deposition. According to the results from uncertainty analysis, future research needs were recommended, among which a global Hg dry deposition network, unified methods for GOM and PBM dry deposition measurements, quantitative methods for GOM speciation, campaigns for comprehensive forest Hg behavior, and more efforts in long-term Hg deposition monitoring in Asia are the top priorities.

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“…Atmospheric Hg 0and Hg(II) in wet deposition exhibit distinct 199 Hg and 200 Hg signatures (Gratz et al, 2010;Chen et al, 2012;Sherman et al, 2012b;Demers et al, 2013;Enrico et al, 2016). Foliar uptake of atmospheric Hg 0 discriminates heavier Hg isotopes, leading to consistently lower δ 202 Hg values reported in foliage compared with atmospheric Hg(0) (Demers et al, 2013;Enrico et al, 2016;Obrist et al, 2017;Yu et al, 2018;Yuan et al, 2018). Using the triple isotopic fingerprint to distinguish between Hg(0) and Hg(II) deposition, an increasing number of studies around the globe have revealed that 60 %-90 % of Hg in soils is derived from Hg(0) uptake by vegetation (Demers et al, 2013;Jiskra et al, 2015;Enrico et al, 2016;Zheng et al, 2016;Obrist et al, 2017).…”

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confidence: 99%

Insights from mercury stable isotopes on terrestrial–atmosphere exchange of Hg(0) in the Arctic tundra

et al. 2019

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Abstract. The tundra plays a pivotal role in the Arctic mercury (Hg) cycle by storing atmospheric Hg deposition and shuttling it to the Arctic Ocean. A recent study revealed that 70 % of the atmospheric Hg deposition to the tundra occurs through gaseous elemental mercury (GEM or Hg(0)) uptake by vegetation and soils. Processes controlling land–atmosphere exchange of Hg(0) in the Arctic tundra are central, but remain understudied. Here, we combine Hg stable isotope analysis of Hg(0) in the atmosphere, interstitial snow air, and soil pore air, with Hg(0) flux measurements in a tundra ecosystem at Toolik Field Station in northern Alaska (USA). In the dark winter months, planetary boundary layer (PBL) conditions and Hg(0) concentrations were generally stable throughout the day and small Hg(0) net deposition occurred. In spring, halogen-induced atmospheric mercury depletion events (AMDEs) occurred, with the fast re-emission of Hg(0) after AMDEs resulting in net emission fluxes of Hg(0). During the short snow-free growing season in summer, vegetation uptake of atmospheric Hg(0) enhanced atmospheric Hg(0) net deposition to the Arctic tundra. At night, when PBL conditions were stable, ecosystem uptake of atmospheric Hg(0) led to a depletion of atmospheric Hg(0). The night-time decline of atmospheric Hg(0) was concomitant with a depletion of lighter Hg(0) isotopes in the atmospheric Hg pool. The enrichment factor, ε202Hgvegetationuptake=-4.2 ‰ (±1.0 ‰) was consistent with the preferential uptake of light Hg(0) isotopes by vegetation. Hg(0) flux measurements indicated a partial re-emission of Hg(0) during daytime, when solar radiation was strongest. Hg(0) concentrations in soil pore air were depleted relative to atmospheric Hg(0) concentrations, concomitant with an enrichment of lighter Hg(0) isotopes in the soil pore air, ε202Hgsoilair-atmosphere=-1.00 ‰ (±0.25 ‰) and E199Hgsoilair-atmosphere=0.07 ‰ (±0.04 ‰). These first Hg stable isotope measurements of Hg(0) in soil pore air are consistent with the fractionation previously observed during Hg(0) oxidation by natural humic acids, suggesting abiotic oxidation as a cause for observed soil Hg(0) uptake. The combination of Hg stable isotope fingerprints with Hg(0) flux measurements and PBL stability assessment confirmed a dominant role of Hg(0) uptake by vegetation in the terrestrial–atmosphere exchange of Hg(0) in the Arctic tundra.

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Gaseous elemental mercury (GEM) fluxes over canopy of two typical subtropical forests in south China

Cited by 34 publications

References 78 publications

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

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

Atmospheric mercury deposition over the land surfaces and the associated uncertainties in observations and simulations: a critical review

Insights from mercury stable isotopes on terrestrial–atmosphere exchange of Hg(0) in the Arctic tundra

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