Support effect of Mn-based catalysts for gaseous elemental mercury oxidation and adsorption

Abstract. Mercury is a contaminant of global concern. It is transported in the atmosphere primarily as gaseous elemental mercury, but its reactivity and deposition to the surface environment, through which it enters the aquatic food chain, is greatly enhanced following oxidation. Measurements and modelling studies of oxidised mercury in the polar to sub-tropical marine boundary layer (MBL) have suggested that photolytically produced bromine atoms are the primary oxidant of mercury. We report year-round measurements of elemental and oxidised mercury, along with ozone, halogen oxides (IO and BrO) and nitrogen oxides (NO2), in the MBL over the Galápagos Islands in the equatorial Pacific. Elemental mercury concentration remained low throughout the year, while higher than expected levels of oxidised mercury occurred around midday. Our results show that the production of oxidised mercury in the tropical MBL cannot be accounted for by bromine oxidation only, or by the inclusion of ozone and hydroxyl. As a two-step oxidation mechanism, where the HgBr intermediate is further oxidised to Hg(II), depends critically on the stability of HgBr, an additional oxidant is needed to react with HgBr to explain more than 50% of the observed oxidised mercury. Based on best available thermodynamic data, we show that atomic iodine, NO2, or HO2 could all play the potential role of the missing oxidant, though their relative importance cannot be determined explicitly at this time due to the uncertainties associated with mercury oxidation kinetics. We conclude that the key pathway that significantly enhances atmospheric mercury oxidation and deposition to the tropical oceans is missing from the current understanding of atmospheric mercury oxidation.

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Investigation of Gaseous Elemental Mercury Oxidation by Non-thermal Plasma Injection Method

Energy & Fuels ◽

10.1021/acs.energyfuels.7b01405 ◽

2017 ◽

Vol 31 (10) ◽

pp. 11013-11018 ◽

Cited By ~ 6

Author(s):

Jinjing Luo ◽

Qiang Niu ◽

Youxian Xia ◽

Yinan Cao ◽

Rupeng Du ◽

...

Keyword(s):

Thermal Plasma ◽

Elemental Mercury ◽

Mercury Oxidation ◽

Injection Method ◽

Gaseous Elemental Mercury ◽

Plasma Injection ◽

Non Thermal Plasma

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Air Concentrations of Gaseous Elemental Mercury and Vegetation–Air Fluxes within Saltmarshes of the Tagus Estuary, Portugal

Atmosphere ◽

10.3390/atmos12020228 ◽

2021 ◽

Vol 12 (2) ◽

pp. 228

Author(s):

Rute Cesário ◽

Nelson J. O’Driscoll ◽

Sara Justino ◽

Claire E. Wilson ◽

Carlos E. Monteiro ◽

...

Keyword(s):

Leaf Area ◽

Elemental Mercury ◽

Ambient Air ◽

Tagus Estuary ◽

Contaminated Site ◽

Gaseous Elemental Mercury ◽

Mercury Flux ◽

Sarcocornia Fruticosa ◽

Air Concentrations

In situ air concentrations of gaseous elemental mercury (Hg(0)) and vegetation–atmosphere fluxes were quantified in both high (Cala Norte, CN) and low-to-moderate (Alcochete, ALC) Hg-contaminated saltmarsh areas of the Tagus estuary colonized by plant species Halimione portulacoides (Hp) and Sarcocornia fruticosa (Sf). Atmospheric Hg(0) ranged between 1.08–18.15 ng m−3 in CN and 1.18–3.53 ng m−3 in ALC. In CN, most of the high Hg(0) levels occurred during nighttime, while the opposite was observed at ALC, suggesting that photoreduction was not driving the air Hg(0) concentrations at the contaminated site. Vegetation–air Hg(0) fluxes were low in ALC and ranged from −0.76 to 1.52 ng m−2 (leaf area) h−1 for Hp and from −0.40 to 1.28 ng m−2 (leaf area) h−1 for Sf. In CN, higher Hg fluxes were observed for both plants, ranging from −9.90 to 15.45 ng m−2 (leaf area) h−1 for Hp and from −8.93 to 12.58 ng m−2 (leaf area) h−1 for Sf. Mercury flux results at CN were considered less reliable due to large and fast variations in the ambient air concentrations of Hg(0), which may have been influenced by emissions from the nearby chlor-alkali plant, or historical contamination. Improved experimental setup, the influence of high local Hg concentrations and the seasonal activity of the plants must be considered when assessing vegetation–air Hg(0) fluxes in Hg-contaminated areas.

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An Integrated Investigation of Atmospheric Gaseous Elemental Mercury Transport and Dispersion Around a Chlor-Alkali Plant in the Ossola Valley (Italian Central Alps)

Toxics ◽

10.3390/toxics9070172 ◽

2021 ◽

Vol 9 (7) ◽

pp. 172

Author(s):

Laura Fantozzi ◽

Nicoletta Guerrieri ◽

Giovanni Manca ◽

Arianna Orrù ◽

Laura Marziali

Keyword(s):

Elemental Mercury ◽

Background Concentration ◽

Dispersion Pattern ◽

Central Alps ◽

Gaseous Elemental Mercury ◽

Mercury Transport ◽

Close Proximity ◽

Potential Impact ◽

Hg Accumulation

We present the first assessment of atmospheric pollution by mercury (Hg) in an industrialized area located in the Ossola Valley (Italian Central Alps), in close proximity to the Toce River. The study area suffers from a level of Hg contamination due to a Hg cell chlor-alkali plant operating from 1915 to the end of 2017. We measured gaseous elemental Hg (GEM) levels by means of a portable Hg analyzer during car surveys between autumn 2018 and summer 2020. Moreover, we assessed the long-term dispersion pattern of atmospheric Hg by analyzing the total Hg concentration in samples of lichens collected in the Ossola Valley. High values of GEM concentrations (1112 ng m−3) up to three orders of magnitude higher than the typical terrestrial background concentration in the northern hemisphere were measured in the proximity of the chlor-alkali plant. Hg concentrations in lichens ranged from 142 ng g−1 at sampling sites located north of the chlor-alkali plant to 624 ng g−1 in lichens collected south of the chlor-alkali plant. A north-south gradient of Hg accumulation in lichens along the Ossola Valley channel was observed, highlighting that the area located south of the chlor-alkali plant is more exposed to the dispersion of Hg emitted into the atmosphere from the industrial site. Long-term studies on Hg emission and dispersion in the Ossola Valley are needed to better assess potential impact on ecosystems and human health.

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Oxidation efficiency and reaction mechanisms of gaseous elemental mercury by using CeO2/TiO2 and CuO/TiO2 photo-oxidation catalysts at low temperatures in multi-pollutant environments

Journal of the Taiwan Institute of Chemical Engineers ◽

10.1016/j.jtice.2021.06.033 ◽

2021 ◽

Author(s):

Jun-Zhu Yang ◽

Iau-Ren Ie ◽

Zu-Bei Lin ◽

Chung-Shin Yuan ◽

Huazhen Shen ◽

...

Keyword(s):

Reaction Mechanisms ◽

Low Temperatures ◽

Elemental Mercury ◽

Oxidation Catalysts ◽

Gaseous Elemental Mercury ◽

Photo Oxidation ◽

Oxidation Efficiency

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Occurrence of Volcanogenic Inorganic Mercury in Wild Mice Spinal Cord: Potential Health Implications

Biological Trace Element Research ◽

10.1007/s12011-021-02890-0 ◽

2021 ◽

Author(s):

A. Navarro-Sempere ◽

M. García ◽

A. S. Rodrigues ◽

P. V. Garcia ◽

R. Camarinho ◽

...

Keyword(s):

Spinal Cord ◽

Inorganic Mercury ◽

Elemental Mercury ◽

Potential Health ◽

Wild Mice ◽

Gaseous Elemental Mercury ◽

Lumbar Level ◽

Quantification Analysis ◽

Spinal Cord Potential ◽

Cord Potential

AbstractMercury accumulation has been proposed as a toxic factor that causes neurodegenerative diseases. However, the hazardous health effects of gaseous elemental mercury exposure on the spinal cord in volcanic areas have not been reported previously in the literature. To evaluate the presence of volcanogenic inorganic mercury in the spinal cord, a study was carried out in São Miguel island (Azores, Portugal) by comparing the spinal cord of mice exposed chronically to an active volcanic environment (Furnas village) with individuals not exposed (Rabo de Peixe village), through the autometallographic silver enhancement histochemical method. Moreover, a morphometric and quantification analysis of the axons was carried out. Results exhibited mercury deposits at the lumbar level of the spinal cord in the specimens captured at the site with volcanic activity (Furnas village). A decrease in axon calibre and axonal atrophy was also observed in these specimens. Given that these are relevant hallmarks in the neurodegenerative pathologies, our results highlight the importance of the surveillance of the health of populations chronically exposed to active volcanic environments.

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