Atmospheric Total Mercury Research Articles

Previously unaccounted atmospheric mercury deposition in a midlatitude deciduous forest

Mercury is toxic to wildlife and humans, and forests are thought to be a globally important sink for gaseous elemental mercury (GEM) deposition from the atmosphere. Yet there are currently no annual GEM deposition measurements over rural forests. Here we present measurements of ecosystem-atmosphere GEM exchange using tower-based micrometeorological methods in a midlatitude hardwood forest. We measured an annual GEM deposition of 25.1 µg ⋅ m-2 (95% CI: 23.2 to 26.7 1 µg ⋅ m-2), which is five times larger than wet deposition of mercury from the atmosphere. Our observed annual GEM deposition accounts for 76% of total atmospheric mercury deposition and also is three times greater than litterfall mercury deposition, which has previously been used as a proxy measure for GEM deposition in forests. Plant GEM uptake is the dominant driver for ecosystem GEM deposition based on seasonal and diel dynamics that show the forest GEM sink to be largest during active vegetation growing periods and middays, analogous to photosynthetic carbon dioxide assimilation. Soils and litter on the forest floor are additional GEM sinks throughout the year. Our study suggests that mercury loading to this forest was underestimated by a factor of about two and that global forests may constitute a much larger global GEM sink than currently proposed. The larger than anticipated forest GEM sink may explain the high mercury loads observed in soils across rural forests, which impair water quality and aquatic biota via watershed Hg export.

Spatiotemporal distribution and long-range transport of atmospheric speciated mercury at three remote islands in Taiwan Strait and South China Sea

This study investigated the spatiotemporal distribution and long-range transport of atmospheric speciated mercury at three remote islands in the Taiwan Strait and the South China Sea. The field measured speciated mercury in the atmosphere was then correlated with criteria air pollutants and meteorological parameters. Air mass trajectory simulation and global fire map were further used to explore potential source regions. Field measurement results showed that the yearly average concentration of gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particulate mercury (PHg) in the target seas were 2.09±0.61 ng/m3, 20.93±7.81 pg/m3, and 150±70 pg/m3, respectively. The highest GEM, GOM, and PHg concentrations were always observed at the Penghu Islands in all seasons. Total gaseous mercury (TGM = GEM+GOM) was the dominant mercury species in the atmosphere, apportioned as 92.46– 96.17% TGM and 3.83– 8.70% PHg, respectively. The seasonal variation of GEM and PHg concentrations were ordered as: spring>winter>fall>summer, while GOM showed different seasonal trends. The lowest concentration of total atmospheric mercury (TAM) was observed in summer since clean air masses were blown mainly from the Pacific Ocean and the Philippines Islands. Air masses came mainly from Central China, North China, and Japan/Korea with the TAM concentrations of 2.90 ± 0.63, 2.68 ± 0.65, and 2.16 ± 0.45 ng/m3, and the frequencies of 19.3%, 18.3%, and 14.3%, respectively. Atmospheric speciated mercury positively correlated to O3, PM2.5, SO2, and NOx, implying that they were consistently emitted from anthropogenic sources in the upwind polluted regions. Overall, the concentrations of atmospheric speciated mercury measured at the three remote islands in the Taiwan Strait and the South China Sea were commonly higher than those in the United States and European countries, but lower than those in Asian countries, with the exception of Japan.

Estimation of atmospheric mercury emission inventory in Tehran Province

In this study, atmospheric mercury emission inventory was estimated from various anthropogenic sources of emission in Tehran province, including stationary, mobile and also natural sources. The mercury emission factors from different sources were obtained using the United Nations Environment Programme, the United States Environmental Protection Agency AP-42 and related papers. Twelve mercury emission stationary point sources including power plants, cement factories, oil refinery and municipal solid waste in Tehran province were considered, as the total amount of mercury released into the air from these sources was estimated at 405.3 kg/year. To estimate the atmospheric mercury emissions from stationary area sources, the amount of fuel consumed by the activity of power plants, cement factories and oil refinery has been deducted from the total amount of fuel consumed in Tehran province, and according to the type of fuel consumed, this amount was estimated at 97.2 kg/year. Other stationary area sources considered in this study include the brick manufacturing, the use of mercury-containing lamps, the use of mercury in dental treatment and thermometers and the total atmospheric mercury emission from these sources was estimated at 120.1 kg/year. The amount of atmospheric mercury emission from mobile sources was estimated at 46.4 kg/year. The atmospheric mercury emission from natural sources are based on the surface type, which includes impervious surfaces such as pavements and permeable surfaces such as soils, was estimated at 434.1 kg/year of mercury emitted into the air. The total atmospheric mercury emission in Tehran province was estimated at 780.1 kg/year.

Resolving a paradox-high mercury deposition, but low bioaccumulation in northeastern Puerto Rico.

At a "clean air" trade winds site in northeastern Puerto Rico, we found an apparent paradox: atmospheric total mercury (THg) deposition was highest of any site in the USA Mercury Deposition Network, but assimilation into the local food web was quite low. Avian blood THg concentrations (n = 31, from eight species in five foraging guilds) ranged widely from 0.2 to 32 ng g-1 (median of 4.3 ng g-1). Within this population, THg was significantly greater at a low-elevation site near a wetland compared to an upland montane site, even when the comparison was limited to a single species. Overall, however, THg concentrations were approximately an order of magnitude lower than comparable populations in the continental U.S. In surface soil and sediment, potential rates of demethylation were 3 to 9-fold greater than those for Hg(II)-methylation (based on six radiotracer amendment incubations), but rates of change of ambient MeHg pools showed a slight net positive Hg(II)-methylation. Thus, the resolution of the paradox is that MeHg degradation approximately keeps pace with MeHg production in this landscape. Further, any net production of MeHg is subject to frequent flushing by high rainfall on chronically wet soils. The interplay of these microbial processes and hydrology appears to shield the local food web from adverse effects of high atmospheric mercury loading. This scenario may play out in other humid tropical ecosystems as well, but it is difficult to evaluate because coordinated studies of Hg deposition, methylation, and trophic uptake have not been conducted at other tropical sites.

How incense and joss paper burning during the worship activities influences ambient mercury concentrations in indoor and outdoor environments of an Asian temple?

This study firstly investigated the species, concentration variation, and emission factors of mercury emitted from the burning of incenses and joss papers in an Asian temple. Both indoor and outdoor speciated mercury (GEM, GOM, and PHg) were sampled by manual samplers, while ambient GEM at an indoor site was in-situ monitored by a continuous GEM monitor. Field measurement results showed that the total atmospheric mercury (TAM) concentrations in indoor and outdoor environments were in the range of 8.03–35.72 and 6.03–31.35 ng/m3, respectively. The indoor and outdoor ratios (I/O) of TAM in the daytime and at nighttime were in the range of 0.64–0.90 and 1.50–2.04, respectively. The concentrations of GEM, GOM, and PHg during the holiday periods were approximately 1–4 times higher than those during the non-holiday periods. GEM was the dominant mercury species in the indoor and outdoor environments and accounted for 63–81% of TAM, while the oxidized mercury accounted for 19–37% of TAM. Burning incenses and joss papers in a combustion chamber showed that the concentration of GEM from joss paper burning ranged from 4.07 to 11.62 μg/m3, or about 13.97 times higher than that of incense burning, while the concentration of PHg from incense burning ranged from 95.91 to 135.07 ng/m3, or about 3.29 times higher than that of joss paper burning. The emission factors of incense burning were 10.39 ng/g of GEM and 1.40 ng/g of PHg, while those of joss paper burning were 12.65 ng/g of GEM and 1.27 ng/g of PHg, respectively. This study revealed that speciated mercury emitted from worship activities had significant influence on the indoor and outdoor mercury concentrations in an Asian temple. Higher intensity of worship activities during holidays resulted in a higher concentration of speciated mercury in indoor and outdoor air, which might cause health threats to worshipers, staffs, and surrounding inhabitants through long-term exposure.

Total atmospheric mercury deposition in forested areas in South Korea

Abstract. In this study, mercury (Hg) was sampled weekly in dry and wet deposition and throughfall and monthly in litterfall, and as it was volatilized from soil from August 2008 to February 2010 to identify the factors influencing the amount of atmospheric Hg deposited to forested areas in a temperate deciduous forest in South Korea. For this location there was no significant correlation between the estimated monthly dry deposition flux (litterfall + throughfall – wet deposition) (6.7 µg m−2 yr−1) and directly measured dry deposition (9.9 µg m−2 yr−1) likely due primarily to Hg losses from the litterfall collector. Dry deposition fluxes in cold seasons (fall and winter) were lower than in warmer seasons (spring and summer). The volume-weighted mean (VWM) Hg concentrations in both precipitation and throughfall were highest in winter, likely due to increased scavenging by snow events. Since South Korea experiences abundant rainfall in summer, VWM Hg concentrations in summer were lower than in other seasons. Litterfall fluxes were highest in the late fall to early winter, when leaves were dropped from the trees (September to November). The cumulative annual Hg emission flux from soil was 6.8 µg m−2 yr−1. Based on these data, the yearly deposition fluxes of Hg calculated using two input approaches (wet deposition + dry deposition or throughfall + litterfall) were 6.8 and 3.6 µg m−2 yr−1, respectively. This is the first reported study which measured the amount of atmospheric Hg deposited to forested areas in South Korea, and thus our results provide useful information to compare against data related to Hg fate and transport in this part of the world.

Speciated atmospheric mercury in the marine boundary layer of the Bohai Sea and Yellow Sea

The objectives of this study are to identify the spatial and temporal distributions of gaseous elemental mercury (GEM), reactive gaseous mercury (RGM), and fine particulate mercury (HgP2.5) in the marine boundary layer (MBL) of the Bohai Sea (BS) and Yellow Sea (YS), and to investigate the relationships between mercury species and meteorological parameters. The mean concentrations of GEM, RGM, and HgP2.5 were 2.03 ng m−3, 2.5 pg m−3, and 8.2 pg m−3 in spring, and 2.09 ng m−3, 4.3 pg m−3, and 8.3 pg m−3 in fall. Reactive mercury (RGM + HgP2.5) represented < 1% of total atmospheric mercury (GEM + RGM + HgP2.5), which indicated that most mercury export in the MBL was GEM and the direct outflow of reactive mercury was very small. Moreover, GEM concentrations over the BS were generally higher than those over the YS both in spring and fall. Although RGM showed a homogeneous distribution over the BS and YS both in spring and fall, the mean RGM concentration in fall was significantly higher than that in spring. In contrast, the spatial distribution of HgP2.5 generally reflected a gradient with high levels near the coast of China and low levels in the open sea, suggesting the significant atmospheric mercury outflow from China. Interestingly, the mean RGM concentrations during daytime were significantly higher than those during nighttime both in spring and fall, while the opposite results were observed for HgP2.5. Additionally, RGM positively correlates with air temperature while negatively correlates with relative humidity. In conclusion, the elevated atmospheric mercury levels in the BS and YS compared to other open seas suggested that the human activities had a significant influence on the oceanic mercury cycle downwind of China.

Origin of oxidized mercury in the summertime free troposphere over the southeastern US

Abstract. We collected mercury observations as part of the Nitrogen, Oxidants, Mercury, and Aerosol Distributions, Sources, and Sinks (NOMADSS) aircraft campaign over the southeastern US between 1 June and 15 July 2013. We use the GEOS-Chem chemical transport model to interpret these observations and place new constraints on bromine radical initiated mercury oxidation chemistry in the free troposphere. We find that the model reproduces the observed mean concentration of total atmospheric mercury (THg) (observations: 1.49 ± 0.16 ng m−3, model: 1.51 ± 0.08 ng m−3), as well as the vertical profile of THg. The majority (65 %) of observations of oxidized mercury (Hg(II)) were below the instrument's detection limit (detection limit per flight: 58–228 pg m−3), consistent with model-calculated Hg(II) concentrations of 0–196 pg m−3. However, for observations above the detection limit we find that modeled Hg(II) concentrations are a factor of 3 too low (observations: 212 ± 112 pg m−3, model: 67 ± 44 pg m−3). The highest Hg(II) concentrations, 300–680 pg m−3, were observed in dry (RH &lt; 35 %) and clean air masses during two flights over Texas at 5–7 km altitude and off the North Carolina coast at 1–3 km. The GEOS-Chem model, back trajectories and observed chemical tracers for these air masses indicate subsidence and transport from the upper and middle troposphere of the subtropical anticyclones, where fast oxidation of elemental mercury (Hg(0)) to Hg(II) and lack of Hg(II) removal lead to efficient accumulation of Hg(II). We hypothesize that the most likely explanation for the model bias is a systematic underestimate of the Hg(0) + Br reaction rate. We find that sensitivity simulations with tripled bromine radical concentrations or a faster oxidation rate constant for Hg(0) + Br, result in 1.5–2 times higher modeled Hg(II) concentrations and improved agreement with the observations. The modeled tropospheric lifetime of Hg(0) against oxidation to Hg(II) decreases from 5 months in the base simulation to 2.8–1.2 months in our sensitivity simulations. In order to maintain the modeled global burden of THg, we need to increase the in-cloud reduction of Hg(II), thus leading to faster chemical cycling between Hg(0) and Hg(II). Observations and model results for the NOMADSS campaign suggest that the subtropical anticyclones are significant global sources of Hg(II).

Mercury mass flow in iron and steel production process and its implications for mercury emission control

The iron and steel production process is one of the predominant anthropogenic sources of atmospheric mercury emissions worldwide. In this study, field tests were conducted to study mercury emission characteristics and mass flows at two iron and steel plants in China. It was found that low-sulfur flue gas from sintering machines could contribute up to 41% of the total atmospheric mercury emissions, and desulfurization devices could remarkably help reduce the emissions. Coal gas burning accounted for 17%–49% of the total mercury emissions, and therefore the mercury control of coal gas burning, specifically for the power plant burning coal gas to generate electricity, was significantly important. The emissions from limestone and dolomite production and electric furnaces can contribute 29.3% and 4.2% of the total mercury emissions from iron and steel production. More attention should be paid to mercury emissions from these two processes. Blast furnace dust accounted for 27%–36% of the total mercury output for the whole iron and steel production process. The recycling of blast furnace dust could greatly increase the atmospheric mercury emissions and should not be conducted. The mercury emission factors for the coke oven, sintering machine and blast furnace were 0.039–0.047gHg/ton steel, and for the electric furnace it was 0.021gHg/ton steel. The predominant emission species was oxidized mercury, accounting for 59%–73% of total mercury emissions to air.

Investigating the impact of local urban sources on total atmospheric mercury wet deposition in Cleveland, Ohio, USA

Abstract Event-based precipitation samples were collected at a downtown industrial and a predominantly upwind rural location in the Cleveland, Ohio metropolitan area from July 2009 through December 2010 to investigate the potential local total mercury (Hg) wet deposition enhancement in a region with a high concentration of coal combustion sources. Total Hg wet deposition for the 18-month period was 6.8 μg m −2 (n = 81) at the rural site and 10.7 μg m −2 (n = 98) at the urban site demonstrating a significant ( p = 0.046) 37% enhancement in deposition between the two sites. Large deposition events (>0.2 μg m −2 ) occurred predominantly from May through October (n = 16 (urban), n = 10 (rural)) and represented from 2 to 8% of total 18-month deposition per event. At the downtown urban site, the average Hg precipitation concentration was 53% higher for these large deposition events. Concurrently measured precipitation events delivered in aggregate 2.4 times more total Hg wet deposition to the urban site compared to the rural site. Hg rainfall concentrations for concurrent events with similar precipitation depth were 2–4 times higher at the urban site and suggest scavenging of local Hg emissions. Further evaluation of these events revealed 83% more total Hg deposition at the urban site from January to December 2010 compared to July to December 2009, while there was 26% more at the rural site during these same time periods. The larger increase in deposition at the urban site in 2010 may be evidence of increased local emissions from sources that were known to be offline during this study period because of an economic recession.

Status of Atmospheric Mercury Research in South Asia: A Review

Mercury (Hg) is a highly toxic metal, which is known as a global pollutant due to its ability to undergo long-range transport in the atmosphere. Methylated mercury can pose serious adverse effects on human health and environment. Mercury is emitted into the atmosphere by various natural and anthropogenic sources. The largest anthropogenic source of mercury is coal combustion, which contributes ~62% of global emissions. Total global emissions of atmospheric mercury are estimated to be 5600 Mg/year from natural and anthropogenic sources, respectively, contributing around 37% and 63% of total atmospheric mercury. About 40% of global anthropogenic emissions are contributed by East and Southeast Asia with the largest emissions from China (75%) followed by South America and Sub-Saharan Africa. Latter regions are mainly responsible due to increase in artisanal and small scale gold mining. The present estimates of mercury emissions have large uncertainties in global budget, which are mainly due to lack of knowledge of mercury exchange between various components of ecosystem with its speciation in spatial and temporal distribution. Special efforts are needed in the regions of growing economy especially in South Asia where atmospheric mercury is almost unattempted. In order to reduce uncertainties and get more realistic emission figures, there is need to develop an extensive monitoring network to measure various forms of mercury in air, soil and aquatic systems in south Asia. Controlling the emissions of global atmospheric mercury is a big challenge to the scientists and policymakers. Probably, it can be achieved by focusing on implementation of the available technologies and by developing new technologies for mercury removal through developing an extensive partnership between industries and governmental organizations.

Bulk Atmospheric Mercury Fluxes for the Northern Great Plains, USA

Total atmospheric bulk mercury (Hg) concentration and deposition were measured from August 2008 to November 2010 at nine locations in the Northern Great Plains, USA using passive bulk mercury samplers. Monthly mercury concentrations ranged from 1.3 to 51.0 ng L−1 with an overall volume weighted mean of 12.9 ng L−1. Normalized daily Hg fluxes ranged from 0.43 to 110 ng m−2 day−1 with higher rates occurring during high precipitation months as rainfall during spring and summer. Annual deposition rates ranged from 5.82 to 9.21 μg m−2 year−1 and were comparable to studies performed at similar latitudes and to estimates from the Mercury Deposition Network (MDN). There was no significant difference (p > 0.05) between measured atmospheric mercury for one colocated bulk Hg sampler and an existing MDN wet-only sampler at Eagle Butte, South Dakota, demonstrating measurement unity between the two sampling techniques in this geographic area.

An Analytical Method development for the Study of Chemical Species of Mercury in the Atmosphere

&#x0D; &#x0D; &#x0D; Introduction: both natural and anthropogenic activities add mercury (Hg) to the atmosphere. The speciation and chemical transformation of mercury in the atmosphere can significantly influence how it is deposited on the earth’s surface. Methods: To better understand the impact of urban emissions on global mercury cycling, we developed an inexpensive technique for the reliable measurement of gaseous oxidized mercury (GOM) in air. This simple technique is based on a thermal decomposition-difference method previously developed by others for aircraft studies of gom in the remote troposphere. measurements of total atmospheric mercury (TAM) were made by decomposing all forms of mercury in ambient air to gaseous elemental mercury (GEM) at 500°c prior to detection using cold vapour atomic fluorescence spectroscopy (CVAFS). The amount of gom was determined through the difference between TAM and GEM values. results and discussion: a diurnal pattern was found for GEM, with the highest concentrations of Hg species found ranging from 2:00 to 5:00 pm and the lowest and most stable values from 9:00 pm to 6:00 am. The amount of GOM was estimated on the 5th floor balcony of pavillon prépresident-Kennedy at université de Québec à montréal to be 14.7 ± 10.3 ng∙m-3 (arithmetic mean from eight groups of Tam-gem differences in the afternoons of july 12 and 14, 2011 and 95% confidence interval). The inconsistent GOM result, in addition to a large error value, suggests the need for further investigation, and to compare the efficiency of this method to previously established methods to identify and quantify the mercury species in urban gom.&#x0D; &#x0D; &#x0D;

Causes of high O3 in the lower free troposphere over the Pacific Northwest as observed at the Mt. Bachelor Observatory

We measured O3, CO, Hg, sub-micron particle scattering of mid-visible light (σsp), and water vapor (WV) at the Mt. Bachelor Observatory (MBO) in central Oregon, USA since 2004. The data were used to identify sources of large ozone enhancements in the lower free troposphere (FT). A total of 25 high-ozone events, defined as time periods when the 8-h averaged O3 mixing ratio was >70.0 ppbv, were recorded. The events occurred between early March and late September. For 18 of the 25 event days we were able to identify sources based on (1) relative enhancements of O3, CO, Hg and WV compared with the corresponding monthly distributions and (2) supporting data from the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model, the Navy Aerosol Analysis and Prediction System (NAAPS) global aerosol model, and Moderate Resolution Imaging Spectroradiometer (MODIS) satellite-derived active fire counts from the Fire Information for Resource Management System (FIRMS). Our analysis suggests that enhanced O3 levels during all the identified events were transported to MBO in the FT and were driven mostly by subsidence of O3-rich air masses from the upper troposphere/lower stratosphere (UT/LS), Asian long range transport (ALRT) and mixed ALRT + UT/LS influences. The UT/LS events were depleted in CO and total atmospheric mercury (TAM) compared to monthly median values. Levels of O3 and CO tended to be anti-correlated during UT/LS events, consistent with transport from clean regions in the UT. Conversely, the ALRT events were characterized by concomitant enhancements in CO and TAM with mean values during each event that were >70th percentile values for the months during which the events occurred. Unlike for UT/LS events, levels of O3 and CO during ALRT events tended to be correlated, consistent with photochemical O3 production in polluted air masses transported across the Pacific. The mixed ALRT + UT/LS events exhibited characteristics that were intermediate between those of the ALRT and UT/LS events. For the classifiable cases the fractional distribution of each event type was: UT/LS, ∼44% (n = 8); ALRT + UT/LS, ∼33% (n = 6); ALRT, ∼22% (n = 4). In terms of the total number of classifiable high-ozone event hours UT/LS, ALRT + UT/LS and ALRT events accounted for ∼52% (t = 85), ∼36% (t = 59) and ∼13% (t = 21), respectively. The results indicate that downward mixing of O3-rich air masses from the UT/LS together with trans-Pacific transport of urban/industrial and biomass burning emissions from the Asian continent are the most important mechanisms for delivering high O3 levels (i.e., 8-h averages >70.0 ppbv) to the lower FT in the Pacific Northwest.

Measurements of atmospheric mercury in Shanghai during September 2009

Abstract. We report on total gaseous mercury (TGM) measurements made in Pudong, Shanghai in August/September 2009. The average TGM was 2.7 ± 1.7 ng m−3. This represents about 90% of the total atmospheric mercury. This is an underestimate for an annual-mean concentration because the meteorology in September favored predominantly easterly oceanic air, replaced in other seasons by airflow from industrial areas. The observed TGM follows a pattern seen in other cities around the world: a background elevated over mean hemispheric background (1.5 ng m−3), and pollution plumes of different magnitude and duration, interspersed with very sharp spikes of high concentration (60 ng m−3). The September 2009 Shanghai measurements are lower than those reported for most other Chinese cities and Mexico City, and similar to concentrations found in some Asian and in North American cities. Such comparisons are tenuous because of differences in season and year of the respective measurements. Our results should not be used for regulatory purposes. We find that the observed TGM are most likely coming from coal fired power plants, smelters and industrial sources, based on its high correlation with NOx, SO2, CO and wind directions.

Mercury contaminations to the ambient air, soil and water compartments in the zinc smelting area in Weining County, Guizhou, China

Guiyang (26~176 106~176 the capital city of Guizhou Province, is located in southwestern China, which is classified as one of the most seriously polluted cities in China. One investigation was carried out to determine total mercury (THg) in surficial soil and some plants in different function districts in center urban areas and at one contrast site in a rural area of Guiyang in 2005. Dried soil and plant samples were digested with aqua regia and HNO3, and THg was measured by CVAFS with Model Tekran| 2500 analyzer. In addition, total atmospheric mercury (TAM) concentrations were measured at different sampling sites from April 2005 to January 2006. THg concentrations in soil of a business district, a residential district, an ordinary industrial district, a tourism district and a rural district were 4.540, 0.358, 0.270, 0.041 and 0.269 mg.kg l , respectively, which are much elevated compared to national background Hg concentration in soil that is 0.038 mg ~ kg -t. THg in moss in four function districts in urban areas ranged from 0.196 to 0.307 mg ~ -1 with an average of 0.258 mg okg -1, which was about 1.5 times that at the contrast site. The highly positive correlation between THg in moss and TAM was produced. THg concentrations in leaves of urban woody plants ranged from 0.068 to 0.181 mg ~ kg -I. Mercury uptake by leaves was in the order of: deciduous plants > evergreen plants. The difference of THg concentrations in leaves of Frimiana simplex from an ordinary industrial district, a traffic district and a residential district was not obvious. However, THg concentrations in leaves of Frimiana simplex at the three sampling sites were about 2 times higher than those in a tourism district. The spatial distribution of the THg concentrations in leaves of Frimiana simplex and the annual average TAM concentrations display no difference.

Seasonal mercury concentrations measured in rural air in Southern Poland: Contribution from local and regional coal combustion

The concentration of total atmospheric gaseous mercury (TGM) and total particulate mercury (TPM) have been measured during one summer campaign (19–29 August 2003) and one winter campaign (26 January–3 February 2004) at a rural site in Poland. Mercury deposition was also measured using bulk samplers. The measurement campaigns were performed in a typical agricultural area of Southern Poland where 85% of the houses use low capacity domestic heating units (DHUs) fuelled with hard coal during the cold season. An average TGM value of 1.63 ± 0.35 ng m - 3 was obtained in the summer campaign, whereas a 2.5 times higher TGM concentration was found during winter. The mean TPM concentration during summer was 0.11 ± 0.05 ng m - 3 while 10 times higher values were obtained during the winter campaign. The mercury deposition was also found to be much higher during winter in comparison to summer. The summer TGM values are at the same level as the annual average TGM at background locations in most West European countries including Scandinavia. The higher TGM values in winter are most likely due to the use of DHUs in the local area. However, both summer and winter TPM concentrations and mercury deposition fluxes are much higher than in most neighbouring West European countries. This probably reflects the regional use of coal combustion for electric energy production and in low-capacity DHUs.

Characterization of size-fractionated particulate mercury in Shanghai ambient air

The size-fractionated particulate mercury in ambient air was collected at the top of a university campus building in Shanghai from March 2002 to September 2003. Wet digestion followed by cold vapor atom adsorption spectroscopy (CVAAS) was employed to analyze total particulate mercury concentration. Two-step extraction was performed to differentiate volatile particle-phase mercury (VPM), reactive particle-phase mercury (RPM) and inert particle-phase mercury (IPM). The average concentrations of mercury in PM1.6, PM8 and total suspended particle (TSP) were 0.058–0.252, 0.148–0.398 and 0.233–0.529 ng m−3, respectively. About 50%–60% of mercury in PM8 was in PM1.6, and about 60%–70% of mercury in TSP was in PM8. Particulate mercury was mainly concentrated on fine particles. The mercury fraction in fine particulate matters (<1.6 μm) was over 4 μg g−1 while 1–2 μg g−1 in TSP. Both were much higher than background values, suggesting that anthropogenic sources are the predominant emission contributors. Seasonal variation indicated that the mercury in TSP in spring was higher than that in summer; however, the mercury in fine particles (<1.6 μm) varied little. The fact that fine particulate mercury (<1.6 μm) was well correlated with sulfate and elemental carbon, but not with fluoride, chloride, nitrate and organic carbon, demonstrates that fine particulate mercury is closely associated with stationary sources and gas–particle transformation. Speciation analysis of mercury showed that VPM fraction decreased with the decrease of particle size, while IPM fraction increased and occupied over 50% in particle <1.6 μm. The detailed species in VPM, RPM and IPM were discussed. Coal burning was estimated to contribute approximately 80% of total atmospheric mercury.

Annual time-series of total filterable atmospheric mercury concentrations in the Arctic

Total atmospheric mercury (TAM) is operationally defined as the sum of gaseous elemental mercury (GEM), gaseous oxidized inorganic mercury (GOIM), which is also called reactive gaseous mercury (RGM), and total filterable mercury (TFM). An annual weekly-integrated time-series of TFM concentrations in ambient air at Alert, Nunavut, Canada from March 1998 to March 1999 is reported in this paper. The observed TFM concentrations ranged from 0 to 0.37 ng m−3 with the highest value occurring in the spring after polar sunrise and the lowest in summer. The average values for the four seasons are 0.086 (March—May), 0.00085 (June—August), 0.0015 (September—November) and 0.013 ng m−3 (December 1998–February 1999) respectively. This pattern is anti-correlated to that of GEM concentration observed at the same location. The GOIM concentration, calculated using the equation [GOIM]=[TAM]−[GEM]−[TFM], is also anti-correlated with GEM concentration. The annual time-series of the TFM operational blank values shows the same temporal pattern as the TFM concentration, with values ranging from 0.00 to 0.011 ng m−3. These results confirm that, in the polar regions, GEM oxidation and atmospheric deposition of mercury occur mainly in the 3-month period after polar sunrise. Incisive laboratory and field experiments are needed to either confirm or rule out the springtime GEM oxidation/conversion mechanisms proposed in this paper.

Time series analysis of atmospheric mercury in Kuujjuarapik/Whapmagoostui (Québec)

Recent mercury depletion events observed in the Arctic have opened the horizon to numerous new aspects on mercury fate and cycling in the environment. Total Gaseous Mercury and other Atmospheric Mercury speciations are measured in Kuujjuarapik/Whapmagoostui (Lat.: 55.30°N; Long.: 77.73°O) along the Hudson Bay (Quebec) with Tekran 2537A, 1130 and 1135 units. The former is measured since August 1999 whereas the latter are measured during springtime periods over the last three years. Mercury Depletion Events are observed at this low latitude region. MDEs are observed between February and April and are occurring during both the day and nighttime periods. Typically, MDE in Kuujjuarapik are related to air temperature. During MDEs, a significant speciation conversion from Hg 0 to RGM and TPM is operating. However, ratios of TPM to RGM conversion are variable in time.