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Chris S Eckley - One of the best experts on this subject based on the ideXlab platform.
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measurement and scaling of air surface mercury exchange from substrates in the vicinity of two nevada Gold Mines
Science of The Total Environment, 2011Co-Authors: Matthieu B Miller, Chris S Eckley, Mae Sexauer GustinAbstract:Abstract The state of Nevada has extensive mineral resources, and is the largest producer of Gold in the USA as well as fourth in world Gold production. Mercury (Hg) is often present in the hydrothermal systems that produce Gold deposits, and can be found in elevated concentrations in Gold ore. As a result, mining of Gold ore in Nevada has been shown to release Hg to the atmosphere from point and non-point sources. This project focused on measurement of air–soil Hg exchange associated with undisturbed soils and bedrock outcrops in the vicinity of two large Gold Mines. Field and laboratory data collected were used to identify the important variables controlling Hg flux from these surfaces, and to estimate a net flux from the areas adjacent to the active Mines as well as that occurring from the mined area pre-disturbance. Mean daily flux by substrate type ranged from 9 ng m − 2 day − 1 to 140 ng m − 2 day − 1 . Periods of net deposition of elemental Hg were observed when air masses originating from a mine site moved over sampling locations. Based on these observations and measured soil Hg concentrations we suggest that emissions from point and non-point sources at the Mines are a source of Hg to the surrounding substrates with the amount deposited not being of an environmental concern but of interest mainly with respect to the cycling of atmospheric elemental Hg. Observations indicate that while some component of the deposited Hg is sequestered in the soil, this Hg is gradually released back to the atmosphere over time. Estimated pre-disturbance emissions from the current mine footprints based on field data were 0.1 and 1.7 kg yr − 1 , compared to that estimated for the current non-point mining sources of 19 and 109 kg yr − 1 , respectively.
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scaling non point source mercury emissions from two active industrial Gold Mines influential variables and annual emission estimates
Environmental Science & Technology, 2011Co-Authors: Chris S Eckley, Mae Sexauer Gustin, Matthieu B Miller, Frank J MarsikAbstract:Open-pit Gold Mines encompass thousands of hectares of disturbed materials that are often naturally enriched in mercury (Hg). The objective of this study was to estimate annual non-point-source Hg emissions from two active Gold Mines in Nevada. This was achieved by measuring diel and seasonally representative Hg fluxes from mesocosms of materials collected from each mine. These measurements provided a framework for scaling emissions over space and time at each mine by identifying the important variables correlated with Hg flux. The validity of these correlations was tested by comparisons with measurements conducted in situ at the Mines. Of the average diel fluxes obtained in situ (92 daily flux measurements), 81% were within the 95% prediction limits of the regressions developed from the laboratory-derived data. Some surfaces at the Mines could not be simulated in the laboratory setting (e.g., material actively leached by cyanide solution and tailings saturated with cyanide solution), and as such in situ ...
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measurement of surface mercury fluxes at active industrial Gold Mines in nevada usa
Science of The Total Environment, 2011Co-Authors: Chris S Eckley, Mae Sexauer Gustin, Frank J Marsik, Matthieu B MillerAbstract:Abstract Mercury (Hg) may be naturally associated with the rock units hosting precious and base metal deposits. Active Gold Mines are known to have point source releases of Hg associated with ore processing facilities. The nonpoint source release of Hg to the air from the large area (hundreds to thousands of hectares) of disturbed and processed material at industrial open pit Gold Mines has not been quantified. This paper describes the field data collected as part of a project focused on estimating nonpoint source emissions of Hg from two active Mines in Nevada, USA. In situ Hg flux data were collected on diel and seasonal time steps using a dynamic flux chamber from representative mine surfaces. Hg fluxes ranged from −2 day −1 for waste rock piles (0.6–3.5 μg g −1 ) to 684,000 ng m −2 day −1 for tailings (2.8–58 μg g −1 ). Releases were positively correlated with material Hg concentrations, surface grain size, and moisture content. Highest Hg releases occurred from materials under active cyanide leaching and from tailings impoundments containing processed high-grade ore. Data collected indicate that as mine sites are reclaimed and material disturbance ceases, emissions will decline. Additionally local cycling of atmospheric Hg (deposition and re-emission) was found to occur.
Jose A Acosta - One of the best experts on this subject based on the ideXlab platform.
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high altitude artisanal small scale Gold Mines are hot spots for mercury in soils and plants
Environmental Pollution, 2013Co-Authors: Tania A Teranmita, Angel Faz, Flor De Maria Salvador, J M Arocena, Jose A AcostaAbstract:Abstract Mercury releases from artisanal and small-scale Gold Mines (ASGM) condense and settle on plants, soils and water bodies. We collected soil and plant samples to add knowledge to the likely transfer of Hg from soils into plants and eventually predict Hg accumulation in livestock around ASGM in Bolivia. Mean contents of Hg in soils range from 0.5 to 48.6 mg Hg kg−1 soil (5× to 60× more compared to control sites) and exceeded the soil Hg threshold levels in some European countries. The Hg contents ranged from 0.6 to 18 and 0.2 to 28.3 mg Hg kg−1 leaf and root, respectively. The high Hg in Poaceae and Rosaceae may elevate Hg accumulation into the food chain because llama and alpaca solely thrive on these plants for food. Erosion of soils around ASGM in Bolivia contributes to the Hg contamination in lower reaches of the Amazon basin.
Matthieu B Miller - One of the best experts on this subject based on the ideXlab platform.
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measurement and scaling of air surface mercury exchange from substrates in the vicinity of two nevada Gold Mines
Science of The Total Environment, 2011Co-Authors: Matthieu B Miller, Chris S Eckley, Mae Sexauer GustinAbstract:Abstract The state of Nevada has extensive mineral resources, and is the largest producer of Gold in the USA as well as fourth in world Gold production. Mercury (Hg) is often present in the hydrothermal systems that produce Gold deposits, and can be found in elevated concentrations in Gold ore. As a result, mining of Gold ore in Nevada has been shown to release Hg to the atmosphere from point and non-point sources. This project focused on measurement of air–soil Hg exchange associated with undisturbed soils and bedrock outcrops in the vicinity of two large Gold Mines. Field and laboratory data collected were used to identify the important variables controlling Hg flux from these surfaces, and to estimate a net flux from the areas adjacent to the active Mines as well as that occurring from the mined area pre-disturbance. Mean daily flux by substrate type ranged from 9 ng m − 2 day − 1 to 140 ng m − 2 day − 1 . Periods of net deposition of elemental Hg were observed when air masses originating from a mine site moved over sampling locations. Based on these observations and measured soil Hg concentrations we suggest that emissions from point and non-point sources at the Mines are a source of Hg to the surrounding substrates with the amount deposited not being of an environmental concern but of interest mainly with respect to the cycling of atmospheric elemental Hg. Observations indicate that while some component of the deposited Hg is sequestered in the soil, this Hg is gradually released back to the atmosphere over time. Estimated pre-disturbance emissions from the current mine footprints based on field data were 0.1 and 1.7 kg yr − 1 , compared to that estimated for the current non-point mining sources of 19 and 109 kg yr − 1 , respectively.
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scaling non point source mercury emissions from two active industrial Gold Mines influential variables and annual emission estimates
Environmental Science & Technology, 2011Co-Authors: Chris S Eckley, Mae Sexauer Gustin, Matthieu B Miller, Frank J MarsikAbstract:Open-pit Gold Mines encompass thousands of hectares of disturbed materials that are often naturally enriched in mercury (Hg). The objective of this study was to estimate annual non-point-source Hg emissions from two active Gold Mines in Nevada. This was achieved by measuring diel and seasonally representative Hg fluxes from mesocosms of materials collected from each mine. These measurements provided a framework for scaling emissions over space and time at each mine by identifying the important variables correlated with Hg flux. The validity of these correlations was tested by comparisons with measurements conducted in situ at the Mines. Of the average diel fluxes obtained in situ (92 daily flux measurements), 81% were within the 95% prediction limits of the regressions developed from the laboratory-derived data. Some surfaces at the Mines could not be simulated in the laboratory setting (e.g., material actively leached by cyanide solution and tailings saturated with cyanide solution), and as such in situ ...
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measurement of surface mercury fluxes at active industrial Gold Mines in nevada usa
Science of The Total Environment, 2011Co-Authors: Chris S Eckley, Mae Sexauer Gustin, Frank J Marsik, Matthieu B MillerAbstract:Abstract Mercury (Hg) may be naturally associated with the rock units hosting precious and base metal deposits. Active Gold Mines are known to have point source releases of Hg associated with ore processing facilities. The nonpoint source release of Hg to the air from the large area (hundreds to thousands of hectares) of disturbed and processed material at industrial open pit Gold Mines has not been quantified. This paper describes the field data collected as part of a project focused on estimating nonpoint source emissions of Hg from two active Mines in Nevada, USA. In situ Hg flux data were collected on diel and seasonal time steps using a dynamic flux chamber from representative mine surfaces. Hg fluxes ranged from −2 day −1 for waste rock piles (0.6–3.5 μg g −1 ) to 684,000 ng m −2 day −1 for tailings (2.8–58 μg g −1 ). Releases were positively correlated with material Hg concentrations, surface grain size, and moisture content. Highest Hg releases occurred from materials under active cyanide leaching and from tailings impoundments containing processed high-grade ore. Data collected indicate that as mine sites are reclaimed and material disturbance ceases, emissions will decline. Additionally local cycling of atmospheric Hg (deposition and re-emission) was found to occur.
Tania A Teranmita - One of the best experts on this subject based on the ideXlab platform.
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high altitude artisanal small scale Gold Mines are hot spots for mercury in soils and plants
Environmental Pollution, 2013Co-Authors: Tania A Teranmita, Angel Faz, Flor De Maria Salvador, J M Arocena, Jose A AcostaAbstract:Abstract Mercury releases from artisanal and small-scale Gold Mines (ASGM) condense and settle on plants, soils and water bodies. We collected soil and plant samples to add knowledge to the likely transfer of Hg from soils into plants and eventually predict Hg accumulation in livestock around ASGM in Bolivia. Mean contents of Hg in soils range from 0.5 to 48.6 mg Hg kg−1 soil (5× to 60× more compared to control sites) and exceeded the soil Hg threshold levels in some European countries. The Hg contents ranged from 0.6 to 18 and 0.2 to 28.3 mg Hg kg−1 leaf and root, respectively. The high Hg in Poaceae and Rosaceae may elevate Hg accumulation into the food chain because llama and alpaca solely thrive on these plants for food. Erosion of soils around ASGM in Bolivia contributes to the Hg contamination in lower reaches of the Amazon basin.
W J Przybylowicz - One of the best experts on this subject based on the ideXlab platform.
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trace element zoning of sulfides and quartz at sheba and fairview Gold Mines clues to mesoarchean mineralisation in the barberton greenstone belt south africa
Ore Geology Reviews, 2014Co-Authors: Andrea Agangi, Axel Hofmann, W J PrzybylowiczAbstract:Abstract The Fairview and Sheba Mines are two of the major Gold Mines in the Paleoarchean Barberton Greenstone Belt of Southern Africa. At these Mines, Gold is associated with quartz–carbonate ± rutile veins and occurs both as “invisible” Gold finely dispersed in sulfides (primarily pyrite and arsenopyrite), and as visible electrum grains hosted in pyrite. Up to approximately 1000 ppm Au are contained in pyrite, and up to approximately 1700 ppm in arsenopyrite. Mapping of trace element distribution in sulfide minerals using electron microprobe and proton probe techniques revealed multiple events of ore formation and Au mineralisation. At Fairview mine, three stages of pyrite formation were identified, the last of which is associated with arsenopyrite, electrum and other sulfide minerals (sphalerite, chalcopyrite, galena, gersdorffite, and Sb-sulfides). At Sheba mine, pyrite was deposited in two stages, and electrum is associated with the second stage. At both Mines, the last stage of sulfide formation is the main stage of Au deposition, and is associated with mobilisation of Au, As, Sb, Cu, Zn, and Ni. The host rock composition seems to have affected the composition of pyrite, since higher Ni and Co concentrations (up to 1.4 and 1.6 wt.%, respectively) have been measured in meta-(ultra)mafic host rocks in comparison with chert and metagreywacke. Arsenopyrite is chemically zoned, and has Sb- and S-rich cores and As- and Ni-rich rims. This zoning indicates variations in fluid compositions (decreasing Sb and increasing Ni), and crystallisation conditions (increasing As content for increasing temperature). Geothermometric estimates based on the As content of arsenopyrite (As ≤ 32 at.%) indicate temperatures up to ~ 420 °C for the crystal rims. Petrographic and cathodoluMinescence observations of quartz associated with Gold mineralisation show only local brittle deformation, and no plastic deformation. This supports the notion that the ore-transporting veins were emplaced late in the deformation history. Variations of cathodoluMinescence of quartz are correlated with changing Al contents (Al ≤ 0.16 wt.%), and can be related to fluctuations in the pH of the mineralising fluids.