Atmospheric Mercury Emissions Research Articles

Atmospheric emissions of mercury from Australian point sources

The UN Global Mercury Assessment (GMA) estimates that atmospheric emissions of mercury from Australian stationary combustion sources were 97.0 tonnes for the year of 1995. This is more than 90% of the estimated emissions from stationary combustion for the whole of North America, and seems abnormally high for a country with a population of around 20 million, in spite of the fact that most of Australia's stationary energy supply is provided by coal. It is also significantly larger than previous estimates of mercury emissions from Australian sources. New estimates of Australian mercury emissions from stationary energy sources, based on both a top down and bottom up approach, are presented. These estimates can be reconciled for black coal fired power stations, but suggest that the bottom up approach (the Australian National Pollutant Inventory) significantly under-estimates emissions from brown coal fired plant, if mercury capture efficiencies in these plants are low, as observed for lignite-fired plant. The major uncertainties in these estimates are the coal mercury content in coals burnt in Australian power stations, and the mercury capture efficiency in particulate control devices used at these stations. Based on these estimates, Australian emissions of mercury from stationary energy are currently 2–8 tonnes/year, significantly lower than the GMA estimate.

Atmospheric mercury emissions from polluted gold mining areas (Venezuela)

Soil, waste rock and mud from mercury-gold amalgamation mining areas of El Callao (Venezuela) are highly enriched in Hg (0.5-500 microg g(-1)) relative to natural background concentrations (<0.1 microg g(-1)). Mercury fluxes to the atmosphere from twelve polluted sites of this area were measured in situ (6 a.m. to 8 p.m.) using a Plexiglas flux chamber connected to a portable mercury analyzer (model RA-915+; Lumex, St. Petersburg, Russia). Mercury fluxes ranged between 0.65 and 420.1 microg m(-2) h(-1), and the average flux range during the diurnal hours was 9.1-239.2 microg m(-2) h(-1). These flux values are five orders of magnitude higher than both reported world background Hg fluxes (1-69 ng m(-2) h(-1)) and the regional values, which are in the range 2-10 ng m(-2) h(-1). The flux results obtained in this study are, however, similar to those measured at Hg polluted sites such as chloro-alkali plants or polymetallic ore mining districts (>100,000 ng m(-2) h(-1)). The results from this study also show that Hg emissions from the soil are influenced by solar radiation, soil temperature and soil Hg concentration. Our data suggest that solar radiation may be the dominant factor affecting Hg degrees emission since the major species of mercury in polluted soil is Hg degrees (85-97% of total Hg). The simple release of Hg degrees vapor is probably the dominant process occurring with incident light in the field. The apparent activation energy for mercury emission indicates that the volatilization of mercury mainly occurred as a result of the vaporization of elemental mercury in soil. The degree of Hg emission differed significantly among the soil sites studied, which may be due to variations in soil texture, organic matter content and soil compaction.

Atmospheric mercury emissions from substrates and fumaroles associated with three hydrothermal systems in the western United States

This paper quantifies atmospheric mercury (Hg) emissions from substrates and fumaroles associated with three hydrothermal systems: Lassen Volcanic Center, California (LVC); Yellowstone Caldera, Wyoming (YC); and Dixie Valley, Nevada (DV). Substrate Hg fluxes were measured using field chamber methods at thermal and nonthermal sites. The highest Hg fluxes (up to 541 ng m−2 h−1) were measured at thermal active areas. Fluxes from altered and unaltered nonthermal sites were &lt;10 ng m−2 h−1 and were comparable to those measured in natural low‐Hg background regions for YC and DV, and at LVC they were slightly elevated. Similarly, reactive gaseous mercury concentrations were higher in thermal active areas. Using a Geographic Information System framework for scaling, estimated area‐average Hg emissions from substrates were 0.9–3.8 ng m−2 h−1 at LVC, 0.8–2.8 ng m−2 h−1 at YC, and 0.4–0.5 ng m−2 h−1 at DV. At LVC, nonthermal areas were the primary substrate source of atmospheric Hg (&gt;98%). At YC, substrate Hg emissions were dominated (50 to 90%) by acidically altered thermal areas. Substrate emissions at DV were low and primarily from nonthermal areas (66% to 75%). Fumarole emissions at LVC (91–146 kg yr−1) and YC (0.18–1.6 kg yr−1 for Mud Volcano) were estimated by applying Hg:H2O and Hg:CO2 ratios in hydrothermal gas samples to H2O and CO2 emissions. Applying total area‐average emissions from substrates and thermal features at LVC, YC, and DV to similar systems across the conterminous United States, yearly atmospheric Hg emissions from active hydrothermal systems are projected to be 1.3–2.1 Mg.

Wildfires threaten mercury stocks in northern soils

With climate change rapidly affecting northern forests and wetlands, mercury reserves once protected in cold, wet soils are being exposed to burning, likely triggering large releases of mercury to the atmosphere. We quantify organic soil mercury stocks and burn areas across western, boreal Canada for use in fire emission models that explore controls of burn area, consumption severity, and fuel loading on atmospheric mercury emissions. Though renowned as hotspots for the accumulation of mercury and its transformation to the toxic methylmercury, boreal wetlands might soon transition to hotspots for atmospheric mercury emissions. Estimates of circumboreal mercury emissions from this study are 15‐fold greater than estimates that do not account for mercury stored in peat soils. Ongoing and projected increases in boreal wildfire activity due to climate change will increase atmospheric mercury emissions, contributing to the anthropogenic alteration of the global mercury cycle and exacerbating mercury toxicities for northern food chains.

The influence of ozone on atmospheric emissions of gaseous elemental mercury and reactive gaseous mercury from substrates

Experiments were performed to investigate the effect of ozone (O 3) on mercury (Hg) emission from a variety of Hg-bearing substrates. Substrates with Hg(II) as the dominant Hg phase exhibited a 1.7 to 51-fold increase in elemental Hg (Hg o) flux and a 1.3 to 8.6-fold increase in reactive gaseous mercury (RGM) flux in the presence of O 3-enriched clean (50 ppb O 3; 8 substrates) and ambient air (up to ∼70 ppb O 3; 6 substrates), relative to clean air (oxidant and Hg free air). In contrast, Hg o fluxes from two artificially Hg o-amended substrates decreased by more than 75% during exposure to O 3-enriched clean air relative to clean air. Reactive gaseous mercury emissions from Hg o-amended substrates increased immediately after exposure to O 3 but then decreased rapidly. These experimental results demonstrate that O 3 is very important in controlling Hg emissions from substrates. The chemical mechanisms that produced these trends are not known but potentially involve heterogenous reactions between O 3, the substrate, and Hg. Our experiments suggest they are not homogenous gas-phase reactions. Comparison of the influence of O 3 versus light on increasing Hg o emissions from dry Hg(II)-bearing substrates demonstrated that they have a similar amount of influence although O 3 appeared to be slightly more dominant. Experiments using water-saturated substrates showed that the presence of high-substrate moisture content minimizes reactions between atmospheric O 3 and substrate-bound Hg. Using conservative calculations developed in this paper, we conclude that because O 3 concentrations have roughly doubled in the last 100 years, this could have increased Hg o emissions from terrestrial substrates by 65–72%.

Estimation of heavy metal emission fluxes on the territory of the NIS

Abstract As the result of our research, the specific procedures to use emission factor methodology were developed and applied for trace metal emission evaluation into the atmosphere over the territory of the former Soviet Union. The existing data on heavy metal emissions were revised as background information from official sources and expert estimations. Source categories and different initial information as well as the concept of spatial emission distribution were defined and observed. The calculated atmospheric emissions of lead, cadmium and mercury were produced among the main source categories of 12 NIS countries for 1990, 1995 and 1997, using modified emission coefficients. Total cadmium emissions into the atmosphere from determined source categories were estimated as 388.4 tonnes in 1990 for the whole domain with reduction by up to 207.0 tonnes per year for 1997. Mercury emissions were estimated as equal to 303.2 tonnes in 1990 and 159.8 tonnes in 1997. Lead emission amounted to 24903.0 tonnes in 1990, and 9652.5 tonnes in 1997. The results of the evaluation demonstrated the general trends of atmospheric heavy metal emissions with a greater decrease during the first half of the 1990s followed later by the rather stable level to be explained by recession in industrial activity and fuel consumption in NIS in that period. The significant spatial variations of atmospheric emissions over vast territories are described based on the results of their distribution according to 1×1 degree grid with remarkably higher values in the location of industrial cities.

A preliminary study on mercury contamination to the environment from artisanal zinc smelting using indigenous methods in Hezhang county, Guizhou, China—Part 1: mercury emission from zinc smelting and its influences on the surface waters

Abstract Zinc smelting is one of the important anthropogenic atmospheric mercury emission sources, but research on mercury emission from this source category is limited. Using a mass balance method, we estimated the average mercury emission factors from artisanal zinc smelting using indigenous method in Hezhang, Guizhou, China to be 155 and 79 g Hg t −1 of Zn produced from sulfide ore and oxide ore, respectively. These emission factors are much higher than the literature value used to estimate mercury emission from zinc smelting in developing countries, which is 25 g Hg t −1 of Zn produced. Annual mercury emission rates from artisanal zinc smelting in this area were calculated from 1989 to 2001. Up to 2003, a few metric tons of mercury was annually emitted to the ambient air from zinc smelting in such a small area ( 2 ), posing a threat to the local environment. It highlighted that artisainal zinc smelting in Hezahng was an important global atmospheric mercury emission source. The local surface waters were seriously contaminated with mercury due to zinc smelting. Apart from the deposition of mercury species was that emitted from zinc smelting, smelting residues are also the sources of mercury contamination to surface water systems.

Atmospheric mercury emissions and speciation at the sulphur bank mercury mine superfund site, Northern California.

One pathway for release of mercury (Hg) from naturally enriched sites is emission to the atmosphere. Elemental Hg, when emitted, will enter the global atmospheric pool. In contrast, if reactive gaseous Hg or Hg2+ (as HgCl2, HgBr2, or HgOH2) is formed, it will most likely be deposited locally. This study focused on the measurement of elemental Hg flux and reactive gaseous Hg concentrations at the Sulphur Bank Superfund Site, an area of natural Hg enrichment with anthropogenic disturbance and ongoing geothermal activity. Mean Hg emissions ranged from 14 to 11000 ng m(-2) h(-1), with the highest emissions from anthropogenically disturbed materials. Reactive gaseous Hg concentrations were the highest ever reported for a natural setting (0.3-76 ng m(-3)). Measured Hg fluxes were used within a Geographic Information System to estimate mercury releases to the atmosphere from the site. Results indicated approximately 17 kg of Hg y(-1) of is emitted to the atmosphere from the 3.8 km2 area, with half from mine waste, ore, and tailing piles and half from relatively undisturbed naturally enriched substrate.

Landfill is an important at-mospheric mercury emission source

Since municipal wastes contain refuses with high mercury contents, incineration of municipal wastes becomes the major anthropogenic atmospheric mercury emission source. In China, landfills are however the main way to dispose of municipal wastes. Total gaseous mercury (TGM) concentrations in landfill gas of Gaoyan sanitary landfill located in suburb of Guiyang City were monitored using a high temporal resolved automated mercury analyzer, and mono-methylmercury (MMHg) and dimethylmercury (DMHg) concentrations in landfill gas were also measured using GC coupled with the cold vapor atomic fluorescence (CVAFS) method. Meanwhile, the TGM exchange fluxes between exposed waste and air and the soil surface of the landfill and air, were measured using low Hg blank quartz flux chamber coupled with high temporal resolved automated mercury analyzer technique. TGM concentrations in landfill gas from half year filling area averaged out at 665.52 ±291.25 ng/m3, which is comparable with TGM concentrations from flue gas of a small coal combustion boiler in Guiyang. The average MMHg and DMHg concentrations averaged out at 2.06 ±1.82 ng/m3 and 9.50±5.18 ng/m3, respectively. It is proven that mercury emission is the predominant process at the surfaces of both exposed wastes and soil of landfill. Landfills are not only TGM emission source, but also methylmercury emission source to the ambient air. There are two ways to emit mercury to the air from landfills, one is with the landfill gas through landfill gas duct, and the other through soil/air exchange. The Hg emission processes from landfills are controlled by meteorological parameters.

A Preliminary Study of the Application of Some Predictive Modeling Techniques to Assess Atmospheric Mercury Emissions from Terrestrial Surfaces

Predictive modeling techniques are applied to investigate their potential usefulness in providing first order estimates on atmospheric emission flux of gaseous soil mercury and in identifying those parameters most critical in controlling such emissions. Predicted data by simulation and statistical techniques are compared to previously published observational data. Results showed that simulation techniques using air/soil coupling may provide a plausible description of mercury flux trends with a RMSE of 24.4 ng m−2 h−1 and a mean absolute error of 10.2 ng m−2 h−1 or 11.9%. From the statistical models, two linear models showed the lowest predictive abilities (R2 = 0.76 and 0.84, respectively) while the Generalized Additive model showed the closest agreement between estimated and observational data (R2 = 0.93). Predicted values from a Neural Network model and the Locally Weighted Smoother model showed also very good agreement to measured values of mercury flux (R2 = 0.92). A Regression Tree model demonstrated also a satisfactory predictability with a value of R2 = 0.90. Sensitivities and statistical analyses showed that surface soil mercury concentrations, solar radiation and, to a lesser degree, temperature are important parameters in predicting airborne Hg flux from terrestrial soils. These findings are compatible with results from recent experimental studies. Considering the uncertainties associated with mercury cycling and natural emissions, it is concluded, that predictions based on simple modeling techniques seem quite appropriate at present; they can be useful tools in evaluating the role of terrestrial emission sources as part of mercury modeling in local and regional airsheds.

Versatile mobile lidar system for environmental monitoring.

A mobile lidar (light detection and ranging) system for environmental monitoring is described. The optical and electronic systems are housed in a truck with a retractable rooftop transmission and receiving mirror, connected to a 40-cm-diameter vertically looking telescope. Two injection-seeded Nd:YAG lasers are employed in connection with an optical parametric oscillator-optical parametric amplification transmitter, allowing deep-UV to mid-IR wavelengths to be generated. Fast switching that employs piezoelectric drivers allows multiwavelength differential absorption lidar for simultaneous measurements of several spectrally overlapping atmospheric species. The system can also be used in an imaging multispectral laser-induced fluorescence mode on solid targets. Advanced LabVIEW computer control and multivariate data processing render the system versatile for a multitude of measuring tasks. We illustrate the monitoring of industrial atmospheric mercury and hydrocarbon emissions, volcanic sulfur dioxide plume mapping, fluorescence lidar probing of seawater, and multispectral fluorescence imaging of the facades of a historical monument.

Gaseous mercury exchange rate between air and water over Baihua reservir, Guizhou, China during cold season

Field measurement campaigns over lake water surface at Baihua reservoir in Guiyang, Southwestern China were conducted to measure mercury flux using a dynamic flux chamber technique coupled with automatic mercury vapor-phase analyzer from October 30 to November 4, 2001. The dynamic flux chamber is made of quartz glass, and has low blanks. Water samples were collected, and dissolved gaseous mercury (DGM), reactive and total mercury concentrations in water were measured using gold trap pre-concentration and AFS detection method. Meanwhile meteorological parameters, such as wind speed, wind direction, intensity of solar radiation, air and water temperature, and relative humidity were monitored using a portable weather station. Water surface is a net atmospheric mercury emission source even at cold season (autumn), and the average mercury emission rate is 3.0 ng/m 2 .h. We observed a strong correlation between wind speed and mercury emission rate, suggesting that strong wind facilitate mercury evaporation process from the water system during cold season. No significant correlations between Hg emission rate and solar radiation, water and air temperature were obtained.

Total gaseous mercury in the atmosphere of Guiyang, PR China

Four measurement campaigns were carried out to monitor total gaseous mercury (TGM) at one site in Guiyang City, PR China in the following periods: April 19–30, 2000; February 26–March 14, 2001; June 26–July 20, 2001; and October 9–November 22, 2001, respectively. High temporal resolved data were obtained by using automated mercury analyzers Gardis 1A and Tekran 2537A. TGM data from all measurement periods followed the typical log normal distribution pattern. The geometric mean of TGM from different seasons were 8.56, 7.45, 5.20 and 8.33 ng m −3 in spring 2000, winter 2001, summer 2001 and autumn 2001, respectively. The overall average TGM covering the sampling periods was 7.39 ng m −3, which is significantly elevated comparing to global background of approximately 1.5–2.0 ng m −3. The major anthropogenic atmospheric mercury emission sources differed significantly among seasons, which caused the seasonal variability of TGM level. Distinct daily variability of TGM was observed among seasons. The daytime TGM concentrations were larger than that of nighttime in spring and winter seasons, while in summer and autumn the opposite daily TGM distribution pattern was observed.

Atmospheric mercury emissions from mine wastes and surrounding geologically enriched terrains

Waste rock and ore associated with Hg, precious and base metal mining, and their surrounding host rocks are typically enriched in mercury relative to natural background concentrations (<0.1 {micro}g Hg g{sup -1}). Mercury fluxes to the atmosphere from mineralized areas can range from background rates (0-15 ng m{sup -2} h{sup -1}) to tens of thousands of ng m{sup -2} h{sup -1}. Mercury enriched substrate constitutes a long-term source of mercury to the global atmospheric mercury pool. Mercury emissions from substrate are influenced by light, temperature, precipitation, and substrate mercury concentration, and occur during the day and night. Light-enhanced emissions are driven by two processes: desorption of elemental mercury accumulated at the soil:air interface, and photo reduction of mercury containing phases. To determine the need for and effectiveness of regulatory controls on short-lived anthropogenic point sources the contribution of mercury from geologic non-point sources to the atmospheric mercury pool needs to be quantified. The atmospheric mercury contribution from small areas of mining disturbance with relatively high mercury concentrations are, in general, less than that from surrounding large areas of low levels of mercury enrichment. In the arid to semi-arid western United States volatilization is the primary means by which mercury ismore » released from enriched sites.« less

Occurrence, emissions and deposition of mercury during coal combustion in the province Guizhou, China

Forty-eight coal samples from the major coal mines in Guizhou were collected by means of subterranean channel sampling. The average mercury content in coal from this Chinese province is 0.53 mg kg-1, which is substantially higher than coal produced in any other province of China. A strong link is proposed to exist between atmospheric mercury emissions and the combustion of coal. During the last two decades, the amount of mercury emitted from coal combustion in Guizhou has increased invariably to 8.3 tons in 1998. Being concentrated to the pyrite fraction in the coal, the implementation of physical coal cleaning is likely to be an effective way to reduce the mercury content. Total and fractionated mercury in air and precipitation was measured in the provincial capital. During a measurement campaign in October 1999, the reactive gaseous mercury (RGM) concentration averaged at 450 pg m-3, which is much higher than that in pristine area (less than 20 pg m-3). The average total mercury in rainwater of 1996 was estimated to be 33 ng L-1, and the total annual wet deposition of mercury in the area was 39 g km-2 in 1996.

Estimating Gaseous Mercury Emissions from Contaminated Floodplain Soils to the Atmosphere with Simple Field Measurement Techniques

The atmospheric emission of mercury (Hg) from a contaminatedwetlands system was studied in the floodplains along the riverElbe (Northern Germany). Results suggest that wetlands can beimportant transformation and phase transfer regions, linking theterrestrial, aquatic and atmospheric compartments of regionalbiogeochemical Hg cycles. Fluxes determined by flux chambermeasurements averaged 43 ± 5 ng m-2 h-1. Additionally,soil gas probe sampling was introduced to determine mercuryconcentrations in soil air. This technique shows some promise fordetecting and confining mercury contamination in soils. We alsopropose that measurements of total gaseous mercury (TGM) in soilair and the near-surface atmosphere, in combination with simplesoil physical parameters, may be suitable for calculatingsemiquantitative estimates of Hg evaporation from contaminatedsoils, based on laminar diffusion considerations. The results arecompared to other Hg flux measurements, and the advantages anddisadvantages of different approaches to quantify Hg emissionsfrom soils are discussed, especially with regard to possiblesystematic bias.

Scaling of atmospheric mercury emissions from three naturally enriched areas: Flowery Peak, Nevada; Peavine Peak, Nevada; and Long Valley Caldera, California

With the development of analytical capabilities that allow for almost real time measurement of mercury concentrations in air, the fluxes of mercury between environment compartments is being more carefully scrutinized. Recent advances have demonstrated that the mercury cycle is much more complicated than previously realized. This study quantified the mercury emissions from three areas with low levels of mercury enrichment associated with precious and base metal mineralization and recent volcanic/geothermal activity. Area emissions were calculated using Geographic Information System technology, and in situ derived mercury fluxes and those parameters found to statistically be dominant in controlling emissions. The most important controls on emission strengths were found to be geologic while environmental parameters such as light and temperature were found to drive the diel pattern typically observed for mercury emissions. Calculated area averaged emissions were 18.5, 10.0, and 13.6 ng/m 2 h for the Flowery Peak, NV, Peavine Peak, NV, and Long Valley Caldera, CA areas, respectively. These emissions are an order of magnitude higher than values applied in global models for natural sources. This study, along with other recent work, demonstrates that natural sources may contribute more mercury than previously recognized to the atmospheric mercury pool.

Estimate of mercury emissions to the atmosphere from petroleum.

An estimate of the contribution of mercury to the atmospheric environment from petroleum processed in the United States is constructed from recent data. The estimate is based on a mass balance approach for mercury in crude oil, in refined products, and in waste streams (air, water, solid waste) from refineries. Although there are insufficient data at present to have a high degree of confidence in the mean amount and range of mercury concentrations in crude oil or in refined products, the framework of the estimate should assist direction for the acquisition of additional data. On the basis of selected data that put the estimated mean concentration of total mercury in crude oil close to 10 ppb, it is calculated that the total amount of mercury in U.S. petroleum processed yearly is slightly over 8000 kg/yr. Of this amount, approximately 6000 kg/yr is estimated to be emitted to the atmosphere from combustion of liquid hydrocarbon fuels, which represents about 10% of the U.S. yearly emission rate of atmospheric mercury from coal combustion. The material balance predicts that the amount of mercury in air emissions from all U.S. refineries is on the order of 1500 kg/yr based on the assumption that fugitive mercury emissions from refineries are negligible. Atmospheric emissions of mercury from fuel oil burned in the United States are estimated in the U.S. EPA Mercury Report to Congress to be approximately 10000 kg/yr, and this estimate may be in error on the high side by a factor of 3-10. If the mean amounts of mercury in U.S. distillate and residual fuel oils are in the range of 5-15 ppb, as suggested by more recent data, then U.S. fuel oil combustion should contribute no more that about 1000-3000 kg/yr (emission ratio = 1) of mercury to the atmospheric burden.

European emissions of atmospheric mercury from anthropogenic sources in 1995

Estimates of atmospheric emissions of mercury from anthropogenic sources in Europe in 1995 are presented with the information on emissions of both total mercury and its major chemical and physical forms. The 1995 anthropogenic emissions of total emissions were estimated to be about 342 tonnes , a decrease of 45% compared to these emissions in 1990. Combustion of fuels, particularly coal has been the major source of anthropogenic emissions contributing to more than half to the total emissions. The emissions from coal combustion have not changed significantly over the past decade. Major decrease has been estimated for emissions from industrial processes, particularly the chlor-alkali production using the Hg cell process. In 1995 the European emissions of anthropogenic mercury contributed about 13% to the global emissions of this element from anthropogenic sources. The anthropogenic Hg emissions in Europe were still higher than the natural emissions in the region, estimated to be about 250– 300 tonnes per year. The accuracy of estimates of anthropogenic emissions of Hg in Europe in 1995 is considered to be between 25 and 50%. The most accurate seem to be the estimates for combustion sources, while the most incomplete data were collected and/or estimated for waste disposal. The emissions of gaseous elemental mercury contributed about 61% to the emissions of the total mercury, while the contribution of gaseous bivalent mercury and particulate mercury was 32 and 7%, respectively.

Examining Source-Receptor Relationships for Mercury in Scandinavia Modelled and Empirical Evidence

The atmosphere remains the major source of mercuryin Swedish ecosystems. Since the late eighties,atmospheric emissions of mercury have drasticallydecreased in Europe. Wet deposition of mercury hasdecreased over the last decade but still exhibitsa clear south-to-north gradient, greatlyinfluenced by source areas in northern and centralEurope. The decreases in emissions can beattributed to both direct measures to close knownpoint sources and a declining economy and energyconsumption in many East European countries.Further reductions of mercury emissions willrequire that other source categories such asindirect emissions from mercury-containingproducts and crematories are be considered.