Four years (2011–2015) of total gaseous mercury measurements from the Cape Verde Atmospheric Observatory

Read, Katie A.; Neves, Luis; Carpenter, Lucy J.; Lewis, Alastair C.; Fleming, Zoë L.; Kentisbeer, John

doi:10.5194/acp-17-5393-2017

Cited by 10 publications

(4 citation statements)

References 55 publications

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“…Figure 2 shows the time series of speciated atmospheric Hg and meteorological parameters during the cruise in the SCS. The GEM concentration during the whole study period ranged from 0.92 to 4.12 ng m −3 with a mean value of 1.52 ± 0.32 ng m −3 (n = 4673), which was comparable to the average GEM level over the global open oceans (Soerensen et al, 2010a), and higher than those at background sites in the Southern Hemisphere (Slemr et al, 2015;Howard et al, 2017), and also higher than those in remote oceans, such as the Cape Verde Observatory station (Read et al, 2017), the Atlantic Ocean (Laurier and Mason, 2007;Soerensen et al, 2013), the equatorial Pacific Ocean (Soerensen et al, 2014) and the Indian Ocean (Witt et al, 2010;Angot et al, 2014), but lower than those in marginal seas, such as the Bohai Sea (BS), Yellow Sea (YS) and East China Sea (ECS) ( Table 1). However, previous studies (Fu et al, 2010;Tseng et al, 2012) conducted in the northern SCS showed that the average GEM concentrations in their study period (Fu et al, 2010;Tseng et al, 2012) were higher than that in this study (Table 1).…”

Section: Estimation Of Sea-air Exchange Flux Of Hgmentioning

confidence: 61%

Speciated atmospheric mercury and sea–air exchange of gaseous mercury in the South China Sea

Wang¹,

Wang²,

Fan³

et al. 2019

Preprint

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Abstract. The characteristics of the reactive gaseous mercury (RGM) and particulate mercury (HgP) in the marine boundary layer (MBL) is poorly understood due in part to sparse data from sea and ocean. Gaseous elemental Hg (GEM), RGM and size-fractioned HgP in marine atmosphere, and dissolved gaseous Hg (DGM) in surface seawater were determined in the South China Sea (SCS) during an oceanographic expedition (3&#8211;28 September 2015). The mean concentrations of GEM, RGM and HgP2.5 were 1.52&#8201;&#177;&#8201;0.32&#8201;ng&#8201;m&#8722;3, 6.1&#8201;&#177;&#8201;5.8&#8201;pg&#8201;m&#8722;3 and 3.2&#8201;&#177;&#8201;1.8&#8201;pg&#8201;m&#8722;3, respectively. Low GEM level indicated that the SCS suffered less influence from human activities, which could be due to the majority of air masses coming from the open oceans as modeled by backward trajectories. Atmospheric reactive Hg (RGM&#8201;+&#8201;HgP2.5) represented less than 1&#8201;% of total atmospheric Hg, indicating that atmospheric Hg existed mainly as GEM in the MBL. The GEM and RGM concentrations in the northern SCS were significantly higher than those in the western SCS, and the HgP2.5 and HgP10 levels in the Pearl River Estuary were significantly higher than those in the open waters of the SCS, indicating that the Pearl River Estuary was polluted to some extent. The size distribution of HgP in PM10 was observed to be bi-modal with a higher peak (5.8&#8211;9.0&#8201;&#956;m) and a lower peak (0.7&#8211;1.1&#8201;&#956;m), but the coarse modal was the dominant size, especially in the open SCS. There was no significant diurnal variation of GEM and HgP2.5, but we found the RGM concentrations were significantly higher in daytime than in nighttime mainly due to the influence of solar radiation. In the northern SCS, the DGM concentrations in nearshore areas were higher than those in the open sea, but this pattern was not significant in the western SCS. The sea&#8211;air exchange fluxes of Hg0 in the SCS varied from 0.40 to 12.71&#8201;ng&#8201;m&#8722;2&#8201;h&#8722;1 with a mean value of 4.99&#8201;&#177;&#8201;3.32&#8201;ng&#8201;m&#8722;2&#8201; h&#8722;1. The annual emission flux of Hg0 from the SCS to the atmosphere was estimated to be 159.6&#8201;tons&#8201;yr&#8722;1, accounting for about 5.54&#8201;% of the global Hg0 oceanic evasion though the SCS only represents 1.0&#8201;% of the global ocean area. Additionally, the annual dry deposition flux of atmospheric reactive Hg represented more than 18&#8201;% of the annual evasion flux of Hg0, and therefore the dry deposition of atmospheric reactive Hg was an important pathway for the input of atmospheric Hg to the SCS.

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Section: Estimation Of Sea-air Exchange Flux Of Hgmentioning

confidence: 61%

Speciated atmospheric mercury and sea–air exchange of gaseous mercury in the South China Sea

Wang¹,

Wang²,

Fan³

et al. 2019

Preprint

View full text Add to dashboard Cite

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“…53 Monthly average Hg(0) data were obtained from. 4,6,43,44,[54][55][56][57][58][59][60][61] Normal Differenced Vegetation Index, (NDVI) were obtained from the NASA Earth 63 The monthly cement production in China was considered constant throughout the year. 64 Normalization of monthly Hg concentration and emission data.…”

Section: Methodsmentioning

confidence: 99%

A vegetation control on seasonal variations in global atmospheric mercury concentrations

et al. 2018

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Anthropogenic mercury emissions are transported through the atmosphere as gaseous elemental mercury (Hg(0)) prior to deposition to Earth's surface. Strong seasonality in atmospheric Hg(0) concentrations in the Northern Hemisphere has been explained by two factors: anthropogenic Hg(0) emissions are thought to peak in winter due to higher energy consumption, and atmospheric oxidation rates of Hg(0) are faster in summer. Oxidationdriven Hg(0) seasonality should be equally pronounced in the Southern Hemisphere, which is inconsistent with observations of constant year-round Hg(0) levels. Here, we assess the role of Hg(0) uptake by vegetation as an alternative mechanism for driving Hg(0) seasonality. We find that at terrestrial sites in the Northern Hemisphere, Hg(0) co-varies with CO2, which is

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“…7 and S3). This is partly because the higher RH and lower air temperature in nighttime were conducive to the removal of RGM (Rutter and Schauer, 2007;Amos et al, 2012). Thirdly, we found that the difference in RGM concentration between different days was large, though there was no significant difference in PAR values (Fig.…”

Section: Daily Variation Of Rgmmentioning

confidence: 78%

“…Figure S3 showed that the RGM concentration in the nighttime was lower than those in the corresponding forenoon and afternoon, except for the measurements in the PRE. This further indicated that (1) the RGM originated from the photo-oxidation of Hg 0 in the atmosphere and (2) the transfer of RGM to Hg P due to higher RH and lower air temperature in nighttime (Rutter and Schauer, 2007;Lee et al, 2016).…”

Section: Daily Variation Of Rgmmentioning

confidence: 91%

Speciated atmospheric mercury and sea–air exchange of gaseous mercury in the South China Sea

Wang

Fan

et al. 2019

Atmos. Chem. Phys.

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The characteristics of the reactive gaseous mercury (RGM) and particulate mercury (Hg P ) in the marine boundary layer (MBL) are poorly understood, due in part to sparse data from the sea and ocean. Gaseous elemental Hg (GEM), RGM, and size-fractionated Hg P in the marine atmosphere, and dissolved gaseous Hg (DGM) in surface seawater, were determined in the South China Sea (SCS) during an oceanographic expedition (3-28 September 2015). The mean concentrations of GEM, RGM, and Hg P 2.5 were 1.52 ± 0.32 ng m −3 , 6.1 ± 5.8 pg m −3 , and 3.2 ± 1.8 pg m −3 , respectively. A low GEM level indicated that the SCS suffered less influence from fresh emissions, which could be due to the majority of air masses coming from the open oceans, as modeled by back trajectories. Atmospheric reactive Hg (RGM + Hg P 2.5 ) represented less than 1 % of total atmospheric Hg, indicating that atmospheric Hg existed mainly as GEM in the MBL. The GEM and RGM concentrations in the northern SCS (1.73 ± 0.40 ng m −3 and 7.1 ± 1.4 pg m −3 , respectively) were significantly higher than those in the western SCS (1.41 ± 0.26 ng m −3 and 3.8 ± 0.7 pg m −3 ), and the Hg P 2.5 and Hg P 10 levels (8.3 and 24.4 pg m −3 ) in the Pearl River estuary (PRE) were 0.5-6.0 times higher than those in the open waters of the SCS, suggesting that the PRE was polluted to some extent. The size distribution of Hg P in PM 10 was observed to be three-modal, with peaks around < 0.4, 0.7-1.1, and 5.8-9.0 µm, respectively, but the coarse modal was the dominant size, especially in the open SCS. There was no significant diurnal pattern of GEM and Hg P 2.5 , but we found that the mean RGM concentration was significantly higher in daytime (8.0 ± 5.5 pg m −3 ) than in nighttime (2.2 ± 2.7 pg m −3 ), mainly due to the influence of solar radiation. In the northern SCS, the DGM concentrations in the nearshore area (40-55 pg L −1 ) were about twice as high as those in the open sea, but this pattern was not significant in the western SCS. The sea-air exchange fluxes of Hg 0 in the SCS varied from 0.40 to 12.71 ng m −2 h −1 with a mean value of 4.99 ± 3.32 ng m −2 h −1 . The annual emission flux of Hg 0 from the SCS to the atmosphere was estimated to be 159.6 t yr −1 , accounting for about 5.54 % of the global Hg 0 oceanic evasion, although the SCS only represents 1.0 % of the global ocean area. Additionally, the annual dry deposition flux of atmospheric reactive Hg represented more than 18 % of the annual evasion flux of Hg 0 , and therefore the dry deposition of atmospheric reactive Hg was an important pathway for the input of atmospheric Hg to the SCS.

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Four years (2011–2015) of total gaseous mercury measurements from the Cape Verde Atmospheric Observatory

Cited by 10 publications

References 55 publications

Speciated atmospheric mercury and sea–air exchange of gaseous mercury in the South China Sea

Speciated atmospheric mercury and sea–air exchange of gaseous mercury in the South China Sea

A vegetation control on seasonal variations in global atmospheric mercury concentrations

Speciated atmospheric mercury and sea–air exchange of gaseous mercury in the South China Sea

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