Earth system modeling of mercury using CESM2 – Part 1: Atmospheric model CAM6-Chem/Hg v1.0

Zhang, Peng

doi:10.5194/gmd-15-3587-2022

Cited by 15 publications

(19 citation statements)

References 80 publications

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“…In contrast, while such a Hg seasonality has been observed in the NH, only a weak Hg seasonality has been observed at SH background sites such as Amsterdam Island and Cape Point (Slemr et al, 2015(Slemr et al, , 2020. It has been proposed that atmospheric Hg seasonality is less pronounced at SH monitoring stations as a consequence of the lower land cover in the SH (19 %) compared to the NH (39 %) and consequently a lesser importance of vegetation GEM uptake as a driver for Hg seasonality (Feinberg et al, 2022;Jiskra et al, 2018;Zhang and Zhang, 2022).…”

Section: Maïdo Lft Gem Seasonality In the Context Of Atmospheric Hg M...mentioning

confidence: 99%

Mercury in the free troposphere and bidirectional atmosphere–vegetation exchanges – insights from Maïdo mountain observatory in the Southern Hemisphere tropics

Koenig

Magand²,

Verreyken³

et al. 2023

Atmos. Chem. Phys.

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Abstract. Atmospheric mercury (Hg) observations in the lower free troposphere (LFT) can give important insights into Hg redox chemistry and can help constrain Hg background concentrations on a regional level. Relatively continuous sampling of LFT air, inaccessible to most ground-based stations, can be achieved at high-altitude observatories. However, such high-altitude observatories are rare, especially in the Southern Hemisphere (SH), and atmospheric Hg in the SH LFT is unconstrained. To fill this gap, we continuously measured gaseous elemental mercury (GEM; hourly) and reactive mercury (RM; integrated over ∼ 6–14 d) for 9 months at Maïdo mountain observatory (2160 m a.s.l.) on remote Réunion Island (21.1∘ S, 55.5∘ E) in the tropical Indian Ocean. GEM exhibits a marked diurnal variation characterized by a midday peak (mean: 0.95 ng m−3; SD: 0.08 ng m−3) and a nighttime low (mean: 0.78 ng m−3; SD: 0.11 ng m−3). We find that this diurnal variation is likely driven by the interplay of important GEM photo-reemission from the islands' vegetated surfaces (i.e. vegetation + soil) during daylight hours (8–22 ng m−2 h−1), boundary layer influences during the day, and predominant LFT influences at night. We estimate GEM in the LFT based on nighttime observations in particularly dry air masses and find a notable seasonal variation, with LFT GEM being lowest from December to March (mean 0.66 ng m−3; SD: 0.07 ng m−3) and highest from September to November (mean: 0.79 ng m−3; SD: 0.09 ng m−3). Such a clear GEM seasonality contrasts with the weak seasonal variation reported for the SH marine boundary layer but is in line with modeling results, highlighting the added value of continuous Hg observations in the LFT. Maïdo RM is 10.6 pg m−3 (SD: 5.9 pg m−3) on average, but RM in the cloud-free LFT might be about twice as high, as weekly–biweekly sampled RM observations are likely diluted by low-RM contributions from the boundary layer and clouds.

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Section: Maïdo Lft Gem Seasonality In the Context Of Atmospheric Hg M...mentioning

confidence: 99%

Mercury in the free troposphere and bidirectional atmosphere–vegetation exchanges – insights from Maïdo mountain observatory in the Southern Hemisphere tropics

Koenig

Magand²,

Verreyken³

et al. 2023

Atmos. Chem. Phys.

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“…2 ), background soils have been suggested as the dominant Hg emission source to the atmosphere in Australia, responsible for 70% of total emissions (Nelson et al 2012 ). The relative importance of soil emission is due to the low anthropogenic Hg emission in the country (Nelson et al 2012 ) and lack of Hg 0 exchange with the NH due to the short atmospheric Hg lifetime of 3–6 months (Horowitz et al 2017 ; Saiz-Lopez et al 2020 ; Shah et al 2021 ; Zhang and Zhang 2022 ). Recent investigations suggest that soil emissions may in fact be balanced by dry deposition and surface uptake at local scales (Fisher and Nelson 2020 ; MacSween et al 2020 ).…”

Section: Background Mercury In Soilsmentioning

confidence: 99%

“…Historical consideration of the global nature of Hg pollution derived in part from the longer earlier estimated atmospheric lifetime of elemental Hg (Hg 0 ) of 12–18 months (Lamborg et al 2002 ; Seigneur et al 2004 ; Lindberg et al 2007 ; AMAP/UNEP 2008), similar to the timescale for interhemispheric air exchange (Geller et al 1997 ; Kersting et al 2020 ). However, more recent estimates suggest a shorter atmospheric lifetime of 3–6 months (Horowitz et al 2017 ; Saiz-Lopez et al 2020 ; Shah et al 2021 ; Zhang and Zhang 2022 ). This shorter lifetime implies that Hg is largely a hemispheric pollutant (Corbitt et al 2011 ; Driscoll et al 2013 ), thus increasingly placing importance towards considering Hg sources, sinks and impacts from a hemispheric perspective.…”

Section: Introductionmentioning

confidence: 99%

A synthesis of mercury research in the Southern Hemisphere, part 1: Natural processes

Schneider

Fisher

Diéguez

et al. 2023

Ambio

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Recent studies demonstrate a short 3–6-month atmospheric lifetime for mercury (Hg). This implies Hg emissions are predominantly deposited within the same hemisphere in which they are emitted, thus placing increasing importance on considering Hg sources, sinks and impacts from a hemispheric perspective. In the absence of comprehensive Hg data from the Southern Hemisphere (SH), estimates and inventories for the SH have been drawn from data collected in the NH, with the assumption that the NH data are broadly applicable. In this paper, we centre the uniqueness of the SH in the context of natural biogeochemical Hg cycling, with focus on the midlatitudes and tropics. Due to its uniqueness, Antarctica warrants an exclusive review of its contribution to the biogeochemical cycling of Hg and is therefore excluded from this review. We identify and describe five key natural differences between the hemispheres that affect the biogeochemical cycling of Hg: biome heterogeneity, vegetation type, ocean area, methylation hotspot zones and occurence of volcanic activities. We review the current state of knowledge of SH Hg cycling within the context of each difference, as well as the key gaps that impede our understanding of natural Hg cycling in the SH. The differences demonstrate the limitations in using NH data to infer Hg processes and emissions in the SH.

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“…Ash samples are assumed in this study to have no Hg adsorbed onto the surface at the time of fragmentation and ejection from the vent. In-plume Hg concentration at the time of all three eruptions was not measured, but assumed from GEM measurements of other volcanic systems (Bagnato et al, 2015) to be 2-3 orders of magnitude larger than the modeled ambient atmospheric concentration of ~1.5 ng m −3 for this area (Zhang and Zhang, 2022).…”

Section: Hg Concentration Analysis Of Ash Samplesmentioning

confidence: 99%

Estimates of volcanic mercury emissions from Redoubt Volcano, Augustine Volcano, and Mount Spurr eruption ash

Kushner

Lopez²,

Wallace³

et al. 2023

Front. Earth Sci.

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Ash is a potential sink of volcanically sourced atmospheric mercury (Hg), and the concentration of particle-bound Hg may provide constraints on Hg emissions during eruptions. We analyze Hg concentrations in 227 bulk ash samples from the Mount Spurr (1992), Redoubt Volcano (2009), and Augustine Volcano (2006) volcanic eruptions to investigate large-scale spatial, temporal, and volcanic-source trends. We find no significant difference in Hg concentrations in bulk ash by distance or discrete eruptive events at each volcano, suggesting that in-plume reactions converting gaseous Hg0 to adsorbed Hg2+ are happening on shorter timescales than considered in this study (minutes) and any additional in-plume controls are not discernable within intra-volcanic sample variability. However, we do find a significant difference in Hg concentration of ash among volcanic sources, which indicates that volcanoes may emit comparatively high or low quantities of Hg. We combine our Hg findings with total mass estimates of ashfall deposits to calculate minimum, first-order Hg emissions of 8.23 t Hg for Mount Spurr (1992), 1.25 t Hg for Redoubt Volcano (2009), and 0.16 t Hg for Augustine Volcano (2006). In particular, we find that Mount Spurr is a high Hg emitting volcano, and that its 1992 particulate Hg emissions likely contributed substantially to the global eruptive volcanic Hg budget for that year. Based on our findings, previous approaches that use long-term Hg/SO2 mass ratios to estimate eruptive total Hg under-account for Hg emitted in explosive events, and global volcanogenic Total Hg estimates need revisiting.

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Earth system modeling of mercury using CESM2 – Part 1: Atmospheric model CAM6-Chem/Hg v1.0

Cited by 15 publications

References 80 publications

Mercury in the free troposphere and bidirectional atmosphere–vegetation exchanges – insights from Maïdo mountain observatory in the Southern Hemisphere tropics

Mercury in the free troposphere and bidirectional atmosphere–vegetation exchanges – insights from Maïdo mountain observatory in the Southern Hemisphere tropics

A synthesis of mercury research in the Southern Hemisphere, part 1: Natural processes

Estimates of volcanic mercury emissions from Redoubt Volcano, Augustine Volcano, and Mount Spurr eruption ash

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