Grantee Research Project Results
Final Report: Light Induced Mercury Volatilization from Substrate Mechanism(s) Responsible and In situ Occurrence
EPA Grant Number: R825249Title: Light Induced Mercury Volatilization from Substrate Mechanism(s) Responsible and In situ Occurrence
Investigators: Gustin, Mae Sexauer
Institution: University of Nevada - Reno
EPA Project Officer: Chung, Serena
Project Period: December 15, 1996 through December 14, 1999 (Extended to December 14, 2000)
Project Amount: $288,645
RFA: Exploratory Research - Air Chemistry & Physics (1996) RFA Text | Recipients Lists
Research Category: Safer Chemicals , Air
Objective:
The two principal objectives of this project, outlined in the original research proposal, were to: (1) determine the mechanisms responsible for light enhanced mercury volatilization from substrate using controlled laboratory experiments; and (2) investigate the effect of ambient light conditions on mercury flux in situ using an eddy correlation technique. For the first objective, the following parameters were to be investigated with respect to their influence on light enhanced emissions: light wavelength, mercury speciation in substrate, and the type of substrate. To understand the observed light enhanced emissions, the speciation of the mercury in substrate must be determined. In the original proposal, mercury speciation in substrate was to be determined using sequential extraction procedures developed by Lechler, et al. (1995) and Revis (1990). In the initial testing of their published procedures, spike recoveries were not good (cf. Sladek and Gustin, 2000). This resulted in the development of another significant objective?developing a chemical extraction protocol for determining mercury speciation in substrate. The protocol developed was compared with two other methods used for the identification of mercury in substrate. For the field objective, an eddy correlation micrometeorological method was initially proposed. After working with researchers representing 10 research institutions, as part of the Nevada STORMS workshop [(organized and hosted by the University of Nevada-Reno (UNR) and consisting of an in situ intercomparison of methods applied towards the measurement of mercury flux (cf. Gustin et al. 1999; 2000)], it was realized that the Modified Bowen Ratio method (cf. Lindberg, et al., 1995; Meyers et al., 1996) was a better method for this project, and that field flux chambers also should be applied. Both of these methods were then applied to understand the in situ light enhanced flux. During the last year of the project, data also were collected on the light enhanced emissions of Hg using field chambers placed within large mesocosms at the Desert Research Institute.
Currently, our understanding of the global biogeochemical cycle of mercury is evolving as more information on the factors controlling the fate and transport of mercury in the environment is revealed. This project provides valuable information on the factors controlling the release of mercury from natural and anthropogenically enriched substrate to the atmosphere. This information is needed to understand the capacity of natural and anthropogenic enriched substrates to act as sources of mercury to the global atmospheric pool. Information developed in the project will help us understand the dynamics of mercury transfers between environmental compartments. This information is critical for determining whether controls on anthropogenic sources of mercury will be realized and for understanding the mechanisms important in controlling the cycling of anthropogenically emitted mercury.
Summary/Accomplishments (Outputs/Outcomes):
Determination of Mercury Speciation in Substrate. To determine the mechanism responsible for light enhancement of mercury emissions, the form of mercury in the substrate must be known. Sequential extraction methods have been applied to this cause (cf. Revis, et al., 1990; Lechler, et al., 1995; Wallschlager, et al., 1998) and more recently, Extended X-ray Absorption Fine Structure Spectroscopy (EXAFS, Kim, et al., 1999) and solid phase Hg thermodesorption or decomposition (Biester and Scholz, 1997). The latter two methods are more direct methods for determination of mercury species than the sequential extraction procedures. The original proposal described the use of published sequential extraction methods for determining mercury species in substrate. Sequential extraction procedures do not allow for direct determination of the mercury species or phases in a substrate, but for the indirect inference of the species based on their extraction chemistry. To check the efficiency of published methods, we applied them to characterized substrates that had been amended with elemental mercury (Hg?), mercuric and mercurous chloride (Hg2Cl2 and HgCl2, respectively) representing reactive Hg species, mercury oxide and HgS, considered to represent the strongly bound fraction in soils. These species will behave differently in the environment: Hg? will be volatilized to the atmosphere, HgCl2 and Hg2Cl2 represent mobile fractions that will readily be transported in aqueous phases, and HgS will remain in situ and/or be broken down gradually over time by weathering.
Methods investigated involved pyrolysis for determination of the volatile phases, chloride extractions for the determination of reactive or soluble phases, and different acid digestions to determine the residual component along with the total mercury concentration in substrate. As a result of the experiments, a temperature of 80?C for 8 hours was decided on as the Hg? or volatile mercury extraction protocol. Assessment of the sequential extraction method involving pyrolysis first and then subsequent leaching with chloride solutions revealed that pyrolysis confounded the results of the leaching experiment. Ammonia chloride was determined to be the most efficient at extraction of HgCl2. Acid digestions that were tested included a 3:7 sulfuric: nitric acid mixture, aqua regia and a 1:1:3 hydrofluoric: nitric: hydrochloric mixture. Aqua regia was found to be more effective that the sulfuric: nitric mixture for some types of sample matrices, and to have a digestive efficiency similar to the HF: HNO3: HCl mixture. Because the use of the extraction methods sequentially was found to remove unintended phases and to affect later extractions, the final extraction protocol consisted of individual extractions (pyrolysis at 80oC for 8 hours, a NH4Cl leach) done on sample splits followed by an aqua regia digestion of the residue.
Extraction methods were initially applied to pure ground glass and autoclaved beach sand amended with the aforementioned mercury species. They were then applied to ground glass amended with vermiculite and iron oxide, and to natural substrates. The presence of organic matter in substrate was found to significantly reduce recovery of elemental and mercury chloride spikes. The presence of iron oxide and vermiculite also interfered with extraction results, but not as significantly as a small (3%) amount of organic material. These results are discussed in depth in Sladek and Gustin (2000a, b) and Sladek and Gustin (in progress a, b).
Because of the strong influence of substrate on the extractions, it was concluded that chemical extraction methods are more appropriate for determination of the potential for mercury mobility in substrate rather than identification of the mercury species present. Through multi-institutional collaboration, chemical extraction results were compared with analysis results on sample splits done by Christopher Kim (a Ph.D. student of Gordon Brown at Stanford University), who applied x-ray absorption spectroscopy (EXAFS) (Kim, et al., 1999) and with Harold Biester (Institute of Environmental Geochemisty, Heidelberg, GE), who applied a thermodesorption method to the determination of mercury speciation in substrate (Biester and Scholz, 1997). EXAFS provides a method for determination of mercury species in substrate for those mercury minerals or phases for which an EXAFS pattern has been established in substrates with mercury concentrations of > 100 g/g. The thermodesorption method allows for qualitative determination of speciation based on the temperature of breakdown of mercury containing compounds also in substrate with mercury concentrations of ~> 100 g/g. For the majority of the substrates studied, which included natural and anthropogenically mercury enriched substrates, mercury was found to be in the residual component of the chemical extraction. These results are consistent with the EXAFS and thermodesorption characterizations. EXAFS revealed that most of the Hg was cinnabar or metacinnabar, both of which are fairly insoluble. Thermodesorption revealed most of the mercury was cinnabar or matrix bound. Given that the mercury concentration in the substrates investigated was > 100 g/g, even if a concentration of < 1 percent is mobilized by volatilization or leaching into solution, the amount released could result in concentrations of environmental concern. Results of the intercomparison are summarized in Sladek et al. (in preparation) and in his Masters Thesis.
Laboratory Chamber Investigation of Light Enhanced Mercury Emissions from Substrate. A well-mixed single pass laboratory gas exchange chamber was used to investigate light enhanced emissions from a variety of substrates. The laboratory chamber is configured so that environmental variables impacting Hg emissions may be precisely controlled (cf. Gustin et al., 1997, 1998, 1999). The sample chambers consisted of a Pyrex cuvette containing a Teflon coated fan. Temperatures within the chamber were controlled with a thermistor and cooling coil. Temperatures of the air within the chamber, the top 1 mm, and the immediate soil surface were determined with thermocouples and an Everest infrared sensor, respectively. Light was generated with a xenon arc lamp with intensity of 40 to 1,040 mole/m2 h measured with a Licor net radiometer and a light wavelength energy band of 500 to >700 nm. The wavelength of light was limited by the use of Pyrex for the gas exchange chamber. No ultraviolet light passed through the Pyrex. Because of these light wavelength limitations, laboratory studies may not account for all observations in the field. Flow of air entering the chamber was regulated using a high precision mass flow controller and was generated using a pure air generator. Some experiments utilized ambient air to determine if there were different responses as a function of air quality. Flux was determined with the following equation:
F = (Co-Ci)/A * Q,
where F is the flux in ng/m2h, Co and Ci are the mercury concentration measured at the chamber inlet and outlet in ng/m3, respectively, A is the area from which emissions are being measured in m2, and Q is the flow of air through the chamber, m3/h.
To explain the observed light enhanced Hg emissions in situ and in the laboratory, Gustin et al. (1998, 1999) proposed two potential mechanisms: desorption of Hg? that has become adsorbed or photoreduction of Hg complexes. Mercury sulfides could be weathering to Hg(SH)2 (g), which was described as being photoreactive (Stromberg, et al., 1991). If Hg(SH)2(g) were forming as a weathering product and migrating towards the surface, Hg could be photoreduced upon interaction with incident light and Hg? released. Alternatively, if Hg? was migrating towards the surface and became oxidized as it approached the surface, this mercury could bind with organic material, sulfides, halides, or iron oxides. Sulfur and iron complexes have been demonstrated to participate in the photoreduction of Hg2+ (cf. Stromberg, et al., 1991; Lin and Pehknonen, 1997). Corderoite - Hg3S2Cl, Radtkeite Hg3S2ClI, and Kenhsuite Hg3S2Cl2 are all photosensitive (McCormack, 1997), with the latter turning black upon exposure to sunlight. In addition, mercury sulfide has long been know to degrade from red to black in sunlight (Kothny, 1971) and does so more readily in cinnabar with high chlorine content.
To investigate the potential light enhancement mechanism(s), research proceeded by addressing several hypothesis. The first hypothesis was that Hg? is the species that exhibits light enhanced emissions, and physical desorption was the primary mechanism. To address this hypothesis, different mercury species were amended to a natural beach quartz sand, which was autoclaved, and to ground glass. The amended species included Hg?, mercury sulfide, mercuric chloride, mercurous chloride, and mercury oxide. Of these pure species, only mercury sulfide exhibited light enhanced emissions. However, all of these species constantly emitted mercury to the air. In addition, a Hg? generating permeation tube was buried in quartz sand to see if Hg? gas emanating from the permeation tube was desorbed from the sand with incident light. No light enhanced emissions were observed. Because quartz sand is fairly inert, it is possible that absorption of gaseous Hg? moving through the substrate did not occur as it would in nature.
A second set of experiments were devised to address the hypotheses that light enhanced emissions are a result of photoreactions with gaseous mercury species or with Hg? that had been transported to the air-substrate interface, oxidized, and chemically bound to become a photoreactive mercury species, which is returned back to its elemental form with incident light. This was tested by burying mercury sulfide, mercury contaminated mill tailings for which a light enhanced emissions had been observed, and an Hg? permeation tube (VICI Metronics) beneath quartz sand and investigating whether light enhanced emissions occurred. Mercury gas constantly made its way from the buried substrate to the atmosphere; however, no light enhanced emissions were observed. As clean air was being used for these experiments, perhaps oxidation of Hg? at the air surface interface was not occurring as it would in ambient air. To address the latter, three experiments were set up such that a layer of Fe oxide was placed on top of the quartz sand beneath which the mercury emitting species was buried to see if any light enhanced effect was observed, and it was not. In one experiment, the layered substrate (sand, mercury permeation tube, sand, iron oxide) was placed in a fume hood with the light on and allowed to sit for a week, and still no light enhancement was observed. Experiments also were done with ambient air rather than clean air. Engle, et al. (2001) observed gaseous mercury absorbtion and release in situ and in laboratory experiments with ambient air.
A third hypothesis was investigated: mercury adsorbed to iron oxides and organic matter will exhibit light enhanced emissions. To address this hypothesis, HgCl2, Hg?, and Hg2Cl2 were amended to iron oxide and organic containing substrates, and light enhanced emissions were investigated. A light enhanced emission of mercury was observed for all substrates, except the Hg? and the Hg2Cl2 amended Fe oxide coated quartz.
Additional experiments with synthetic and natural substrates were done with 1-mm and 1-cm thick layers of substrate spread in a petri dish. The same degree of light enhancement was observed regardless of the thickness of the layer, indicating that the light enhanced emissions is a surface driven process. Light enhanced emissions also were found to be an immediate response to incident light.
In summary, mercury sulfide is the only pure phase tested that exhibited light enhanced emissions. Iron oxide amended with mercury chloride, and organic material amended with Hg? and mercury chloride exhibited light enhanced emissions. Gases emanating from buried substrate that exhibited light enhanced emissions in the laboratory and in situ, such as cinnabar ore, and the Carson River tailings exhibited no light enhancement. All mercury species and mercury containing substrates constantly emitted mercury to the air. The activation energy for experiments that determined mercury flux as a function of temperature in the dark for all phases was + 15 percent of that for the transition of Hg? -liquid to Hg? -vapor of 14 kcal/mole. Experiments were done within the visible range of light with no ultraviolet light present. This was a limitation of the pyrex chamber.
The effect of light on Hg emissions from geologically and anthropogenically Hg-enriched substrate also was measured with the gas exchange chamber. Some of the results of these investigations were reported in Gustin et al. (1999). The work in CY 2000 focused on measurement of the influence of light on emissions from geologic substrate for which at least one of the three mercury speciation methods described above had been applied. For most of these substrates, the light enhanced emissions were greater than 1.5 to 14 times that occurring in the dark at the same surface temperature.
In comparison of the magnitude of the light enhancement with the determined mercury speciation, in general, those substrates with EXAFS as having metacinnabar exhibited the greatest light enhancement. Higher light enhanced emissions also were observed for substrate that H. Biester identified as containing matrix bound species. Data from Objectives 1 and 2 currently are being compiled into a manuscript discussing the light enhanced emissions from naturally enriched and amended substrates (Gustin, in preparation).
In Situ Measurement of the Light Effect on Mercury Emissions. The least invasive technique for measuring air-surface exchange of Hg is the application of a micrometeorological approach (cf. Gustin et al., 1999; Gustin, 1999). While field flux chambers are useful for measuring Hg emissions from small surface areas (<0.1 m2), micrometeorological techniques integrate fluxes over much larger areas (~50 to 200 m2). This project originally set out to apply an eddy correlation micrometeorological method to the measurement of mercury flux. After the Nevada STORMS field intercomparison, held in September 1997, at the Steamboat Springs Geothermal Area, NV (cf. Gustin et al., 1999; Gustin, 1998), it was realized that the Modified Bowen Ratio approach, as developed by Lindberg et al. (1995), was better suited for the measurement of mercury flux from the complex terranes where both natural and anthropogenic Hg- contamination is present. In addition, the NV STORMS project provided data that demonstrated that field flux chambers provide a better experimental design for understanding the influence of environmental parameters on flux. As a result of these outcomes of the NV STORM International Workshop (cf. Gustin, et al., 1999; Gustin and Lindberg, 2000), a Modified Bowen Ratio micrometeorological method and in situ field chamber measurements were both applied in this project towards the measurement of in situ light enhanced emissions.
The Modified Bowen Ratio approach entails the measurement of both the flux and gradient of passive scalars (e.g., CO2, H2O, temperature) in the surface air layer to derive an empirical turbulent transfer coefficient, Kz. With the advent of sensitive and accurate thermocouples (0.01oC), measurements of temperature gradients can be combined with measurements of water vapor gradients to obtain sensible (QH) and latent (QE) heat fluxes and the transfer coefficient Kz using the classic Bowen Ratio. The Kz determined from these approaches is then applied to Hg gradients measured at the same heights as the other parameters to calculate the Hg flux. The relationship used to calculate the Hg flux is given by:
FHg = FS CHg/CS = -KzCsCHg
where FHg is the flux of Hg, FS is the flux of a passive scalar (e.g., CO2, H2O, heat), DCHg and DCS are the concentration gradients of Hg and the passive scalar, respectively, measured at the same heights above the surface. In order to derive Kz, a variety of meteorological measurements are required: wind speed and direction; CO2/H2O concentrations; temperature gradient at two to four heights above the surface; Hg vapor concentration gradient at two to four heights measured using a Tekran mercury analyzer; global and net radiation; soil temperature and soil heat flux; relative humidity; and barometric pressure. In addition, to derive Kz using the Modified Bowen Ratio approach, turbulent fluctuations of vertical velocity (w') and H2O concentrations (c'H2O) must be measured with fast response instruments, i.e., a sonic anemometer for w' and a krypton hygrometer for c'H2O. The covariance, w' c'H2O, provides the moisture flux in the Modified Bowen Ratio method, which is considered an improvement over using latent heat flux in the classic Bowen Ratio method since QE depends on the surface energy budget balance, and a more direct way to measure moisture flux. Dr. Robert Keislar of Desert Research Institute, Reno, NV, and Dr. Frank Marsik, University of Michigan, collaborated in development and application of the Modified Bowen Ratio method for this project.
An optimized field flux chamber, constructed of polycarbonate (surface area of 0.027 m2; internal volume of 1 liter) with 8 holes (d=1.25 cm) evenly distributed 1 cm from the bottom of the chamber with a single outlet located at the top of the chamber, was used. This chamber was developed as a result of the Nevada STORMS field intercomparison of micrometeorological and field chambers for the measurement of mercury flux (cf. Gustin et al., 1999).
In CY 1998, chamber and micrometeorological flux measurements were made from tailings in Seven Mile Canyon of the Carson River Superfund site, NV, three times at the Steamboat Springs Geothermal area, and the Ivanhoe Mining District. At the New Idria Mining District, only field chamber measurements were made due to the complexity of the terrain. In CY 1999, field chamber and micrometeorological flux measurements were made at an anthropogenically Hg contaminated site near Gold Hill, NV, within the Carson River Superfund site, and using a field flux chamber at the McLaughlin Gold Mine, California, and Ivanhoe, Nevada (Engle et al., 2001). In the field, a variety of environmental factors influence emissions, including light, temperature, turbulence, substrate mercury concentration, vegetative cover, precipitation, etc. In order to determine the overall magnitude of influence of light enhanced emissions, these other factors must be considered. Statistical analysis is used to weigh the importance of various factors controlling flux. Data developed during this project demonstrate the significant effect of light on Hg emissions from substrate, some of this is summarized below; however, a more in depth discussion is being prepared in a manuscript that will be submitted to Environmental Science and Technology this spring. In addition to field studies in CY2000, additional data was collected with field flux chambers placed upon mercury contaminated soils contained within large mesocosms or EcoCELLS as part of an EPA EPSCoR project investigating the role of plants in the biogeochemical cycling of mercury between soils, plants, and the atmosphere. The EcoCELLS consist of 7.3 x 5.5 x 4.5 m (l x w x d) mesocosms designed as open flow mass balance systems. Each EcoCELL has three soil containers with ~5 tonnes of gravel overlain by ~ 4.5 tonnes of mercury amended substrate. The EcoCELLS allow for precise manipulation of environmental conditions and measurement of system level response with high resolution. Within the EcoCELLS, the experimental setting is precisely controlled and monitored, unlike the field where environmental parameters may rapidly change.
At all of the field sites discussed above, the light enhanced emissions of mercury from substrate with none to little subsequent increase in soil temperature was demonstrated. A rapid increase in emissions was observed in the morning with incident radiation and, on cloudy days, the flux would mimic the shadowing and lighting of the sites. At the Carson River Superfund site, one experiment was done by artificially lighting tailings at night and a 100-fold increase in emissions was observed (dark = -4 ng/m2h to light 93 ng/m2h). At New Idria, California, emissions from soils doubled (300 ng/m2h to 600 ng/m2h) as morning light irradiated the soil.
One way to understand the light enhanced emissions is to calculate the activation energy associated with mercury flux. Lindberg et al. (1995) demonstrated that the activation energy for mercury flux could be calculated as a function of temperature using the following equation:
Ln flux = - Ez/(T * R) + constant,
where T is the temperature in Kelvins, and R is the gas constant. The activation energy is the volatilization of Hg? liquid to gas and it is 14 kcal/mole. Gustin et al. (1997) found that the Ea for mercury flux from Carson River tailings cores measured in the dark using the gas exchange chamber described above was between 16.4 to 25.7 kcal/mole, and for cinnabar ore it was 18.3 kcal/mole. Zhang et al. (2001) recently discussed that absorption of photo energy by gaseous Hg? could decrease the apparent activation energy calculated as a result of the desorbtion of mercury from soils. The activation energy associated with the flux from soils in the EcoCELLs was 10.9 kcal/mole for the night and 17.9 kcal/mole for the day. The fact that a lower activation energy was calculated for mercury emissions at night with respect to the energy needed for volatilization of elemental mercury may be due to the migration of mercury gas that has been produced within the substrate and its continuous movement across the sediment-air interface, promoted by turbulence within the system. The higher activation energy calculated for the day suggests that more energy than just that needed for the volatilization of elemental mercury liquid to gas is being consumed to release the mercury from the substrate. The substrate at DRI was amended with mercury contaminated mill tailings from the Carson River Superfund site. These tailings have been demonstrated in situ and in the laboratory to have a very strong light enhanced emissions. Because there is more energy that is required for the simple phase transition of mercury to occur suggests that light energy is being used to generate elemental mercury. Carpi and Lindberg (1997) reported a higher activation energy than necessary for the phase transition of liquid Hg? to the gaseous form for sewage sludge amended soils, and attributed this to photoreduction. Based on results of laboratory experiments, some sort of photoreduction is most likely responsible for the higher activation energy associated with flux from the DRI soils. For the DRI data, the correlation between the natural logarithm of mercury flux and light r2 = 0.58 was much better than that with temperature r2 =0.17. Activation energies are being compiled for all field sites, mentioned above, as part of a manuscript describing in situ light enhanced emissions. In general, at geothermally active areas, activation energies for both day and nighttime emissions were lower than the activation energy of elemental mercury liquid -----> gas, suggesting that the geothermal influence on mercury emissions is great at these sites. In contrast to the results obtained in the mesocosm experiments, activation energies calculated for day and nighttime fluxes, measured at a site with almost background concentrations of mercury in the Ivanhoe Mining district, were 7 and 23, respectively. The lower activation energy during the day may reflect the energy of the sun being able to desorb mercury that was bound as Hg? gas to the site. Elemental mercury gas was recorded as being deposited to this site at night. This could account for the high activation energy calculated for the night.
In situ emissions of mercury are a function of a variety of environmental parameters. It appears that both desorbtion of deposited gaseous mercury and photoinduced reactions are associated with the observed light enhanced reactions. In situ data is being compared with the speciation results of the first objective and the laboratory results of the second objective to provide a clear picture of the mechanisms of light enhanced mercury emissions. This information currently is being summarized into a journal article that will be submitted to Environmental Science and Technology.
References:
Biester H, Scholz C. Determination of mercury binding forms in contaminated soils: mercury pyrolysis versus sequential extractions. Environmental Science and Technology 1997;31:233-239.
Capri A, Lindberg SE. Sunlight-mediated emissions of elemental mercury from soil amended with municipal sewage sludge. Environmental Science and Technology 1997;31:2085-2091.
Engel MA, Gustin MS, Zhang H. Quantifying natural source mercury emissions from the
Ivanhoe Mining District, North-Central Nevada, USA. Atmospheric Environment July 2001 (submitted for publication).
Sexauer GM, Lindberg S, Marsik F, Casimir A, Ebinghaus R, Edwards G, Fitzgerald C,
Kemp J, Kock H, Leonard T, London J, Majewski M, Owens J, Piolote M, Poissant L, Rasmussen P, Schaledlich F, Schneeberger D, Schroeder W, Sommary J, Turner R, Vette A, Wallschlaeger D, Ziao X. The Nevada storms mercury flux methods intercomparison. Journal of Geophysical Research?Atmospheres 1999;104:21,829-21,830.
Gustin MS, Lindberg SE, Austin K, Coolbaugh M, Vetter A, Zhang Z. Assessing the contribution of natural sources to regional atmospheric mercury budgets. The Science of the Total Environment 2000;259:61-71.
Gustin MS, Lindberg SE. Assessing the contribution of natural sources to the global mercury cycle: the importance of intercomparing dynamic flux measurements. Fresenius' Journal of Analytical Chemistry 2000;366:417-422.
Gustin MS, Rasmssen P, Edwards G, Schroeder W, Kemp J. Application of a laboratory gas exchange. Chamber for assessment of in situ mercury emissions. Journal of Geophysical Research?Atmospheres 1999;104 D17(21):873-878.
Gustin MS. Nevada mercury emissions project: mercury flux measurements?an intercomparison and assessment. Electric Power Research Institute, Published Report, 1998.
Gustin MS, Maxey RA, Rasmussen P, Beister H. Mechanisms influencing the volatile loss of mercury from soil. Symposium Volume of the Air and Waste Management Association on the Measurement of Toxic and Related Air Pollutants, Cary, NC, 1998, pp. 224-235.
Gustin MS, Taylor GE, Maxey RA. Effect of temperature and air movement on the flux of
elemental mercury from substrate to the atmosphere. Journal of Geophysical Research 1997;102:3891-3898.
Kim CS, Brown Jr GE, Ryutba JJ. Characterizations and speciation of mercury-bearing mine
waste using x-ray absorption spectroscopy. Science of the Total Environment 1999;261:157-168.
Kothny EL. Three phase equilibrium of mercury in nature, in trace metals in the environment.
Symposium volume for the Water, Air and Waste Chemistry Meeting of the American Chemical Society, Washington, DC, September 15, 1971.
Lechler PJ, Miller JR, Hsu L-C, Desilets MO. Understanding mercury mobility at the Carson
River Superfund Site, NV, USA: interpretation of mercury speciation results from mill tailings,
soils and sediments. Symposium Volume for the 10th International Conference on Heavy Metals in the Environment, Hamburg, GE, 1995.
Lin C, Pehkonen SO. Aqueous free radical chemistry of mercury in the presence of iron
oxides and ambient aerosol. Atmospheric Environment 1997;31:4125-4137.
Lindberg SE, Kim KH, Meyers TP, Owens JG. A micrometeorological gradient approach for
Quantifying air/surface exchange of mercury vapor: tests over contaminated soils. Environmental Science and Technology 1995;29:126-135.
McCormack J. Mercury sulf-halide minerals and crystalline phases, and experimental formation conditions, in the system Hg3S2Cl2-Hg3S2Br2-Hg3S2I2. Thesis, 1997.
Meyers TP, Hall ME, Lindberg SE, Kim K. Use of the modified Bowen-ratio technique to
measure fluxes of trace gases. Atmospheric Environment 1996;30(19):3321-3329.
Revis NW, Osborne TR, Holdsworth G, Hadden C. Mercury in soil: a method for assessing acceptable limits. Archives of Environmental Contamination and Toxicology 1990;19:221-226.
Sladek, C, Gustin MS. Evaluation of sequential extraction methods for mercury and application for determining the mobility of mercury in mine waste. Applied Geochemistry (to be submitted for publication, May 2001).
Sladek C, Gustin MS. Evaluation of methods for predicting the potential mobility of mercury in mine waste. Geologic Society of America National Meeting, Reno, NV, November 2000.
Sladek C, Gustin MS. Investigation of sequential extraction methods for determination of mercury species in sediments. Proceedings of the 25th International Conference on Heavy Metals in the Environment, Ann Arbor, MI, August 2000.
Sladek C, Gustin MS. Assessing the mobility of mercury in mine waste. Symposium Volume, Assessing and Managing Mercury from Historic and Current Mining Activities, San Francisco, CA, November 2000.
Stromberg D, Stromberg A, Wahlgren U. Relativistic quantum calculations on some mercury sulfide molecules. Water, Air and Soil Pollution 1991;56:681-695.
Wallschlager D, Desai M, Spengler M, Wilken R-D. Mercury speciation in floodplain soils and sediments along contaminated river transect. Journal of Environmental Quality 1998; 27:1034-1044.
Zhang H, Lindberg SE, Markis FJ, Keeler GJ. Mercury air/surface exchange kinetics of background soils of the Tahquamenon River watershed in the Michigan upper peninsula. Water, Air and Soil Pollution 2001;126:151-169.
Journal Articles on this Report : 2 Displayed | Download in RIS Format
Other project views: | All 10 publications | 3 publications in selected types | All 3 journal articles |
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Gerlach RW, Gustin MS, Van Emon JM. On-site mercury analysis of soil at hazardous waste sites by immunoassay and ASV. Applied Geochemistry 2001;16(3):281-290. |
R825249 (Final) |
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Gustin MS, Rasmussen P, Edwards G, Schroeder W, Kemp J. Application of a laboratory gas exchange chamber for assessment of in situ mercury emissions. Journal of Geophysical Research – Atmospheres 1999;104(D17):21,873-21,878. |
R825249 (1999) R825249 (Final) |
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Supplemental Keywords:
atmosphere, soil, chemical transport, bioavailability, heavy metals, mercury, ecosystem protection, scaling, environmental chemistry,, Scientific Discipline, Air, Water, air toxics, Environmental Chemistry, Ecology and Ecosystems, Mercury, anthropogenic disturbances, geochemical cycling, contaminated sites, photoreactive, Superfund sites, exposure and effects, chemical flux, volatile organic species, mercury cycling, light induced mercury volatilization, air-water interface, lake ecosystemsRelevant Websites:
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.