TGM Concentrations Research Articles

Concurrent measurements of atmospheric Hg in outdoor and indoor at a megacity in Southeast Asia: First insights from the region

Atmospheric mercury (Hg) is a critical indoor (ID) air pollutant and necessitates stringent monitoring. However, studies have primarily focused on Hg outdoors (OD) compared to ID, with no investigations conducted within the Southeast Asia (SEA) region. In this study, total gaseous Hg (TGM) concentrations and human exposure levels were investigated across various site characteristics in Ho Chi Minh City (HCMC), a megacity in SEA. The measured TGM concentrations for OD and ID were 5.12 ± 6.87 ng m−3 (1.20–48.7 ng m−3) and 34.5 ± 60.3 ng m−3 (1.26–271.9 ng m−3). The overall ID/OD ratio was 5.01 (0.77–9.3), signifying markedly elevated ID TGM concentrations. This ratio increases in the following order: shopping malls (1.50) < hospitals (3.21) < chemical laboratories (5.76) < households (11.7). Notably, sites associated with Hg incidents and the utilization of Hg-contained chemicals demonstrate notably high ID/OD levels, ranging from 8.0 to 40.1. The use of Hg-containing chemicals within the chemical laboratory serves as a significant contributor to heightened ID TGM levels. Non-combustion Hg sources, therefore, play an important role in inducing the ID TGM level. The hazard index (HQ) values observed for ID and OD were 0.1 and 0.01, respectively, indicating a negligible risk of exposure to TGM within the study area. However, HQ values recorded within laboratory environments employing Hg-associated chemicals and dental hospitals were 1–17 times greater compared to other sites. The present work provides new insight into the non-combustion ID source of TGM and was helpful for upcoming studies in exploring potential sources of TGM in megacities.

Spatiotemporal variations of atmospheric mercury at urban and suburban areas in Southern Vietnam megacity: A preliminary year-round measurement study

Atmospheric mercury (Hg) pollution studies in peninsular Southeast Asia (PSEA) are currently experiencing shortage on spatiotemporal coverage due to limited observation data. Therefore, our study provided year-round (May 2022–April 2023) atmospheric Hg data at two urban and one suburban site in Ho Chi Minh City (HCMC) Vietnam - a megacity in PSEA. Higher total gaseous Hg (TGM) levels at 2 urban sites of 2.49 ± 0.86 ng m−3 (Nguyen Van Cu) and 2.12 ± 0.49 ng m−3 (Linh Trung) were observed as compared to the suburban site of 1.76 ± 0.50 ng m−3 (Can Gio) which suggests the influence of anthropogenic Hg sources. Higher TGM concentration in October 2022–January 2023 as opposed to May 2022–September 2022 at all 3 sites reflected the influence of abrupt change in air mass origins and transport pathways in southern Vietnam. Backward trajectories (BWTs) and concentration-weighted trajectory (CWT) models further suggested East Asian outflow from northeast (NE) direction as a prominent TGM source in HCMC. Our two case studies in June and December 2022 helped to distinguish the impacts of local accumulation besides long-range atmospheric Hg transport towards TGM levels in HCMC. We also attempted to address TGM public health concerns wherein a minimal hazard quotient (HQ < 1) implied insignificant Hg health risk via inhalation pathways. Our study strives to offer crucial information to fill the Hg data gap as well as seeks to explore the impact of monsoon drives on Hg pollution in the PSEA region.

Vegetation Mediated Mercury Flux and Atmospheric Mercury in the Alpine Permafrost Region of the Central Tibetan Plateau.

Measurements of land-air mercury (Hg) exchanges over vegetated surfaces are needed to further constrain Hg fluxes over vegetated terrestrial surfaces. Yet, knowledge of land-air Hg dynamics in alpine grasslands remains poor. Hg fluxes over an alpine meadow were measured throughout a full vegetation period in the central Tibetan Plateau (TP). This TP grassland served as a small source of atmospheric total gaseous Hg (TGM) during vegetation period (0.92 μg m-2). Hg fluxes decreased logarithmically during plant growing season, resulting from the influence of vegetation by light shading and plant Hg uptake, although the latter might be minor due to low biomass at this site. Temporal patterns of TGM indicated the importance of land-air dynamics in regulating TGM levels. During the plant emergence, diel pattern of TGM covaried with Hg emission fluxes resulting in lower concentrations at night and higher concentrations in afternoon. During all other vegetation stages, TGM showed minima before dawn and "morning peak" shortly after sunrise, in conjunction with corresponding Hg fluxes showing sink before dawn and source after sunrise. Moreover, TGM concentrations showed a decreasing trend with plant growing, further indicating the role of vegetation in driving seasonal TGM variations by regulating land-air Hg dynamics.

Evidence for Nonstomatal Uptake of Hg by Aspen and Translocation of Hg from Foliage to Tree Rings in Austrian Pine.

To determine whether trees are reliable biomonitors of air mercury (Hg) pollution concentrations were measured in bark, foliage, and tree rings. Data were developed using 4-year old Pinus and Populus trees grown from common genetic stock in Oregon and subsequently transferred to four air treatments differing in gaseous oxidized mercury (GOM) chemistry and total gaseous Hg (TGM) concentrations. Soil of a subset of trees was spiked with HgBr2 in solution to test for root uptake. Results indicate no significant effect of the soil spike or GOM compounds on tree tissue Hg concentrations. TGM treatment had a significant effect on Pinus and Populus foliage, and Pinus year 5 growth ring concentrations. Populus foliar Hg concentrations were highest in the exposure where 24 h TGM concentrations were highest, indicating the importance of the nonstomatal pathway for uptake. Pinus tree ring concentrations were correlated to day time TGM concentrations suggesting Hg accumulation into tree rings is by way of the stomata and subsequent translocation by way of phloem. Populus leaves and Pinus rings can be used as biomonitors for TGM concentrations over space. However, the use of trees as temporal proxies requires further investigation due to radial translocation observed in active sapwood tree rings.

Distribution of gaseous and particle-bound Hg concentrations at the sites representative for urban and non-urban zones of Silesia Province

The basic features of the distribution of total gaseous (TGM) and particle-bound mercury (PBM) concentrations were determined for a five locations representative for urban (Bielsko-Biała, Lubliniec, Zabrze) and rural areas (Godów, Złoty Potok) of Silesia Province. Gaseous mercury concentrations were measured (1) continuously - the automatic 1h TGM measurements in Zloty Potok and Zabrze and (2) non-continuously manual 24h TGM measurements with a pre-concentration of the Hg on gold traps (Bielsko-Biała, Lubliniec, Godów). The PBM concentrations were measured non-continuously by taking PM2.5 samples. The Hg content was determined by using a CVAAS method. The highest average concentration of TGM was recorded in Zabrze (2.8ng/m3), significantly lower (2.0ng/m3) in Bielsko-Biała and in the non-urban station in Godów, the lowest concentration (&lt;2.0 ng/m3) was observed in Lubliniec and at the regional background station in Zloty Potok. The results obtained for TGM concentrations exceeded the European average level of 1.5 ng/m3 (AirBase, 2014). The highest average PBM concentration, associated with PM2.5, was obtained in Zabrze (70pg/m3), more than 20% lower results were obtained in Bielsko-Biała and Godów, finally, the lowest one (lower by about 40% in comparison with Zabrze) were obtained in Lubliniec and Złoty Potok. Moreover, an enrichment of Hg concentration in PM was observed with the increasing of the PM content, during the heating season.

Seasonal Variations of Total Gaseous Mercury at a French Coastal Mediterranean Site

The seasonal variation and spatial distribution of atmospheric particles at three islands in the Taiwan Strait were investigated. Atmospheric particles (PM10) were collected at three offshore islands (i.e., Kinmen islands, Matsu islands, and Penghu Islands) and two coastal regions (i.e., Xiamen and Fuzhou) in the years of 2008–2012. Field sampling results indicated that the average PM10 concentrations at the Kinmen islands were generally higher than other sampling sites, suggesting that a superimposition phenomenon was regularly observed during the air pollution episodes at Kinmen Islands and Xiamen region. PM10 samples were analyzed for their chemical composition, including water-soluble ions, metallic elements, and carbonaceous content. The most abundant water-soluble ionic species of PM10 were recognized as SO42–, NO3–, and NH4+, indicating that PM10 was mainly composed of secondary inorganic aerosols. Although natural crustal elements dominated the metallic content of PM10, the most abundant anthropogenic metals of PM10 were Zn and Pb. Enrichment factor calculations showed that Ni, Cr, and Zn were the enriched elements emitted mainly from anthropogenic sources. Moreover, the OC concentration of PM10 was always higher than that of EC at all sampling sites. High OC/EC ratios of PM10 were commonly observed at the sampling sites on the Matsu Islands, the Fuzhou region, and the Penghu Islands. Source apportionment results indicated that vehicular exhausts were the main source of PM10, and followed by industrial boilers, secondary aerosols, soil dusts, biomass burning, petrochemical plants, steel plants, oceanic spray, and cement plants at the island and coastal sampling sites in the Taiwan Strait. Highlights ► Investigation of 2 years of TGM at a French coastal Mediterranean site. ► Daily variations of TGM are observed, due to local industrial or urban activities. ► Seasonal variations are due to the dispersion of pollutants in the troposphere. ► High TGM concentrations are due to air masses coming from local or regional sources.

Characteristics and potential sources of atmospheric mercury at a subtropical near‐coastal site in East China

AbstractTo evaluate the impact of regional mercury (Hg) emissions and understand possible source regions of atmospheric Hg in Eastern China, 2 year observation for speciated atmospheric Hg was conducted at the Dameishan Atmospheric Observatory, a mountain site near the east coast of China. The observed concentration of total gaseous Hg (TGM) was 3.3 ± 1.4 ng m−3. During the sampling period, gaseous oxidized Hg and particulate bound Hg were 6.7 ± 4.3 pg m−3 and 180 ± 110 pg m−3 in winter and 5.9 ± 3.4 pg m−3 and 130 ± 100 pg m−3 in spring, respectively. The relatively high mean concentration of TGM was mainly caused by regional anthropogenic emissions and occasional long‐range transport from domestic source regions. Seasonal variation in the TGM concentration was observed with lower values in the wet monsoon season (from May to September) and higher values in the dry monsoon season (from October to April). Backward trajectories and potential source contribution function analysis suggested that anthropogenic Hg emission from coal combustion in the Yangtze River Delta region was the most likely cause for the elevated TGM concentrations. Relatively clean air originating from the East China Sea was the most possible cause for the observed low TGM concentrations. Positive correlation between TGM concentration and air quality index suggests that emissions that influenced regional air quality contributed to the elevated TGM concentrations.

Impacts of Mercury Pollution Controls on Atmospheric Mercury Concentration and Occupational Mercury Exposure in a Hospital.

Mercury (Hg) and Hg-containing products are used in a wide range of settings in hospitals. Hg pollution control measures were carried out in the pediatric ward of a hospital to decrease the possibility of Hg pollution occurring and to decrease occupational Hg exposure. Total gaseous Hg (TGM) concentrations in the pediatric ward and hair and urine Hg concentrations for the pediatric staff were determined before and after the Hg pollution control measures had been implemented. A questionnaire survey performed indicated that the pediatric staff had little understanding of Hg pollution and that appropriate disposal techniques were not always used after Hg leakage. TGM concentrations in the pediatric ward and urine Hg (UHg) concentrations for the pediatric staff were 25.7 and 22.2% lower, respectively, after the Hg pollution control measures had been implemented than before, which indicated that the control measures were effective. However, TGM concentrations in the pediatric ward remained significantly higher than background concentrations and UHg concentrations for the pediatric staff were remained significantly higher than the concentrations in control group, indicating continued existence of certain Hg pollution.

Observation and analysis of speciated atmospheric mercury in Shangri-La, Tibetan Plateau, China

Abstract. This study reports the concentrations and potential sources of speciated atmospheric mercury at the Shangri-La Atmosphere Watch Regional Station (SAWRS), a pristine high-altitude site (3580 m a.s.l.) in Tibetan Plateau, China. Total gaseous mercury (TGM, defined as the sum of gaseous elemental mercury, GEM, and gaseous oxidized mercury, GOM), GOM and particulate-bound mercury (PBM) were monitored from November 2009 to November 2010 to investigate the characteristics and potential influence of the Indian summer monsoon (ISM) and the Westerlies on atmospheric transport of mercury. The mean concentrations (± standard deviation) of TGM, PBM and GOM were 2.55 ± 0.73 ng m−3, 38.82 ± 31.26 pg m−3 and 8.22 ± 7.90 pg m−3, respectively. A notable seasonal pattern of TGM concentrations was observed with higher concentrations at the beginning and the end of the ISM season. High TGM concentrations (&gt; 2.5 ng m−3) were associated with the transport of dry air that carried regional anthropogenic emissions from both Chinese domestic and foreign (e.g., Myanmar, Bay of Bengal, and northern India) sources based on analysis of HYSPLIT4 back trajectories. Somewhat lower PBM and GOM levels during the ISM period were attributed to the enhanced wet scavenging. The high GOM and PBM were likely caused by local photo-chemical transformation under low RH and the domestic biofuel burning in cold seasons.

Long-Term Measurments of Atmospheric Mercury Species (TGM, TPM) and Hg Deposition in the Silesian Region, Poland – Concept of the Mercury Deposition Coefficient

Abstract The aim of this work was to identify concentration levels of different chemical forms of mercury (TGM, TPM) in the ambient air in selected areas of the Silesian Region, characterized by low and high mercury emission. Based on the obtained data TGM and TPM concentration levels were determined. The project also focused on determination of dry and wet deposition of mercury compounds. Data concerning TGM and TPM flux rates in the ambient air and data on mercury deposition were used to determine a deposition coefficient. The coefficient was calculated as a share of mercury deposition on the land surface (dry and wet) to the amount of this contaminant transported with loads of air in the form of TGM and TPM in a given measurement station. At both monitoring stations the deposition coefficient did not exceed 0.2 %. The idea of calculating the deposition coefficient based on the analysis of TGM and TPM flux rate is a new solution. The proposed deposition coefficient allows to quantify information on a selected contaminant concentration and its potential impact resulting from deposition. Further studies on the deposition coefficient may contribute to the development of methods for estimating the impact of contaminants contained in the ambient air on other environmental components based on the analyses of the contaminant flux rate.

An estimation of mercury concentrations in the local atmosphere of Almadén (Ciudad Real Province, South Central Spain) during the twentieth century.

We show the first estimations of long-term (100years, 1900 to 2000) total gaseous mercury concentrations (TGM) in the urban area of Almadén. The estimation was carried out by comparing data on known metallic mercury production with measured TGM concentrations. The estimated diurnal background level ranges from 60 to 120ngm(-3) and corresponds to periods when the metallurgical complex (cinnabar roasting plant) was shut down. The average TGM concentration during the period from 1900 to 2000 was about 600ngm(-3) (with peaks above 1,200ngm(-3)). Additionally, a 24-h-based TGM monitoring program has highlighted significant differences between the diurnal and nocturnal concentrations, particularly during the warmer months. In this regard, given that the average nocturnal to diurnal ratio is 2.12, we suggest that the average nocturnal concentrations must have exceeded 1,200ngm(-3), and peak nocturnal concentrations could have reached levels up to 2,400ngm(-3). Our estimations indicate that most parts of the town of Almadén were generally exposed to TGM concentrations in air that exceed the World Health Organization air quality guideline for Hg (1,000ngm(-3)) for countryside and urban areas.

Projections of atmospheric mercury levels and their effect on air quality in the United States

Abstract. The individual and combined effects of global climate change and emissions changes from 2000 to 2050 on atmospheric mercury levels in the United States are investigated by using the global climate-chemistry model, CAM-Chem, coupled with a mercury chemistry-physics mechanism (CAM-Chem/Hg). Three future pathways from the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) are considered, with the A1FI, A1B and B1 scenarios representing the upper, middle and lower bounds of potential climate warming, respectively. The anthropogenic and biomass burning emissions of mercury are projected from the energy use assumptions in the IPCC SRES report. Natural emissions from both land and ocean sources are projected by using dynamic schemes. TGM concentration increases are greater in the low latitudes than they are in the high latitudes, indicative of a larger meridional gradient than in the present day. In the A1FI scenario, TGM concentrations in 2050 are projected to increase by 2.1–4.0 ng m−3 for the eastern US and 1.4–3.0 ng m−3 for the western US. This spatial difference corresponds to potential increases in wet deposition of 10–14 μg m−2 for the eastern US and 2–4 μg m−2 for the western US. The increase in Hg(II) emissions tends to enhance wet deposition and hence increase the risk of higher mercury entering the hydrological cycle and ecosystem. In the B1 scenario, mercury concentrations in 2050 are similar to present level concentrations; this finding indicates that the domestic reduction in mercury emissions is essentially counteracted by the effects of climate warming and emissions increases in other regions. The sensitivity analyses show that changes in anthropogenic emissions contribute 32–53% of projected changes in mercury air concentration, while the independent contribution by climate change and its induced natural emissions change accounts for 47–68%.

Waste disposal sites as sources of mercury in the atmosphere in the coastal zone of the Gulf of Gdańsk (southern Baltic Sea)

Abstract Elemental mercury re-emission into the air from an old burial ground in Gdańsk Letnica and from a modern landfill in Gdańsk Szadółki resulted in noticeably increased TGM concentrations from the urban background level of 1.9 ng m−3 to a maximum value of 164.4 ng m−3. Hgtot concentrations in the soil of the burial ground ranged from 37.3 to 4817.3 ng g−1 and in the surrounding water: from 22.0 to 55.0 ng dm−3. The highest Hgtot concentrations in the modern landfill (Gdańsk Szadółki) were reported for the unsorted waste: 36.1–972.8 ng g−1. Laboratory experiments on the re-emission of Hg(0) into the air showed that emission from soil was stimulated by solar radiation and from the water — additionally by turbulent mixing.

Observations of atmospheric Hg species and depositions in remote areas of China

From September 2007, we conducted continuous measurements of speciated atmospheric mercury (Hg) and atmospheric mercury depositions at five remote sites in China. Four of these sites were involved in the Global Mercury Observation System (GMOS) as ground-based stations. These stations were located in the northwest, southwest, northeast, and east part of China, respectively, which represent the regional atmospheric Hg budgets in different areas of China. The preliminary results showed that mean TGM concentrations were in the range of 1.60 - 2.88 ng m -3 , with relatively higher levels observed at sites in Eastern China and Southwestern China and lower levels at sites in Northeastern and Northwestern China. TGM concentrations at remote sites of China were also higher than those reported from background sites in North America and Europe, and this is corresponding very well with the Chinese great anthropogenic Hg emissions. Gaseous oxidized mercury (GOM) and particulate bounded mercury (PBM) were in the ranges of 3.2 - 7.4 pg m -3 and 19.4 - 43.5 pg m -3 , respectively. The preliminary result on precipitation showed mean precipitation THg concentrations were in the range of 2.7 - 18.0 ng L -1 .

Atmospheric mercury pollution at an urban site in central Taiwan: Mercury emission sources at ground level

Total gaseous mercury (Hg) (TGM), gaseous oxidized Hg (GOM), and particulate-bound Hg (PBM) concentrations and dry depositions were measured at an urban site in central Taiwan. The concentrations were 6.14±3.91ngm−3, 332±153, and 71.1±46.1pgm−3, respectively. These results demonstrate high Hg pollution at the ground level in Taiwan. A back trajectory plot shows the sources of the high TGM concentration were in the low atmosphere (<500m) and approximately 50% of the air masses coming from upper troposphere (>500m) were associated with low TGM concentrations. This finding implies that Hg is trapped in the low atmosphere and comes from local Hg emission sources. The conditional probability function (CPF) reveals that the plumes of high TGM concentrations come from the south and northwest of the site. The plume from the south comes from two municipal solid waste incinerators (MSWIs). However, no significant Hg point source is located to the northwest of the site; therefore, the plumes from the northwest are hypothesized to be related to the combustion of agricultural waste. Dry deposition fluxes of Hg measured at this site considerably exceeded those measured in North America. Overall, this area is regarded as a highly Hg contaminated area because of local Hg emission sources.

Mercury distribution in the soil–plant–air system at the Wanshan mercury mining district in Guizhou, Southwest China

The level of mercury bioaccumulation in wild plants; the distribution of bioavailable Hg, elemental Hg, and total Hg in soil; and the concentration of total gaseous Hg (TGM) in ambient air was studied at three different mining sites (SiKeng [SK], WuKeng [WK], and GouXi [GX]) in the Wanshan mercury mining district of China. Results of the present study showed that the distribution of soil total Hg, elemental Hg, bioavailable Hg, and TGM varies across the three mining sites. Higher soil total Hg (29.4-1,972.3 mg/kg) and elemental Hg (19.03-443.8 mg/kg) concentrations were recorded for plots SK and WK than for plot GX. Bioavailable Hg was lower at plot SK and GX (SK, 3-12 ng/g; GX, 9-14 ng/g) than at plot WK (11-1,063 ng/g), although the TGM concentration in the ambient air was significantly higher for plot GX (52,723 ng/m(3) ) relative to WK (106 ng/m(3) ) and SK (43 ng/m(3)). Mercury in sampled herbage was elevated and ranged from 0.8 to 4.75 mg/kg (SK), from 2.17 to 34.38 mg/kg (WK), and from 47.45 to 136.5 mg/kg (GX). Many of the sampled plants are used as fodder or for medicinal purposes. High shoot Hg concentrations may therefore pose an unacceptable human health risk. Statistical analysis of the recorded data showed that the Hg concentration in plant shoots was positively correlated with TGM and that the Hg concentration in roots was positively correlated with the bioavailable Hg concentration in the soil. The bioaccumulation factor (BAF) in the present study was defined with reference to the concentration of bioavailable Hg in the soil (Hg([root]) /Hg([bioavail])). Three plant species, Macleaya cordata L., Achillea millefolium L., and Pteris vittata L., showed enhanced accumulation of Hg and therefore may have potential for use in the phytoremediation of soils of the Wanshan mining area.

Atmospheric mercury over the marine boundary layer observed during the third China Arctic Research Expedition

TGM measurements on board ships have proved to provide valuable complementary information to measurements by a ground based monitoring network. During the third China Arctic Research Expedition (from July 11 to September 24, 2008), TGM concentrations over the marine boundary layer along the cruise path were in-situ measured using an automatic mercury vapor analyzer. Here we firstly reported the results in Japan Sea, North Western Pacific Ocean and Bering Sea, where there are rare reports. The value ranged between 0.30 and 6.02 ng/m 3 with an average of (1.52 ± 0.68) ng/m 3, being slightly lower than the background value of Northern Hemisphere (1.7 ng/m 3). Notably TGM showed considerably spatial and temporal variation. Geographically, the average value of TGM in Bering Sea was higher than those observed in Japan Sea and North Western Pacific Ocean. In the north of Japan Sea TGM levels were found to be lower than 0.5 ng/m 3 during forward cruise and displayed obviously diurnal cycle, indicating potential oxidation of gaseous mercury in the atmosphere. The pronounced episode was recorded as well. Enhanced levels of TGM were observed in the coastal regions of southern Japan Sea during backward cruise due primarily to air masses transported from the adjacent mainland reflecting the contribution from anthropogenic sources. When ship returned back and passed through Kamchatka Peninsula TGM increased by the potential contamination from volcano emissions.

Atmospheric mercury species measured in Guiyang, Guizhou province, southwest China

Atmospheric mercury (Hg) species were measured in Guiyang City, the capital of Guizhou province, southwestern China at the Guiyang Monitoring Station Agency (GMSA) from September to November 2008 and at the Institute of Geochemistry, Chinese Academy of Sciences (IGCAS) during February, May, and July, 2009. Monitoring results found elevated concentrations of all three Hg species in ambient air in Guiyang. Large temporal and spatial variation patterns in the resulting data were also obtained. The overall average TGM concentrations at the GMSA and IGCAS sampling sites were 7.4±4.8ngm−3 and 6.2±5.1ngm−3, respectively. The average Hg(p) and RGM concentrations at GMSA were 1330pgm−3 and 24pgm−3, and at IGCAS were 250pgm−3 and 19pgm−3, respectively. It is hypothesized that local anthropogenic sources and the seasonal variability result in the high degree of spatial and temporal variability.

Elevated atmospheric deposition and dynamics of mercury in a remote upland forest of southwestern China

Mt. Gongga area in southwest China was impacted by Hg emissions from industrial activities and coal combustion, and annual means of atmospheric TGM and PHg concentrations at a regional background station were 3.98 ng m −3 and 30.7 pg m −3, respectively. This work presents a mass balance study of Hg in an upland forest in this area. Atmospheric deposition was highly elevated in the study area, with the annual mean THg deposition flux of 92.5 μg m −2 yr −1. Total deposition was dominated by dry deposition (71.8%), and wet deposition accounted for the remaining 28.2%. Forest was a large pool of atmospheric Hg, and nearly 76% of the atmospheric input was stored in forest soil. Volatilization and stream outflow were identified as the two major pathways for THg losses from the forest, which yielded mean output fluxes of 14.0 and 8.6 μg m −2 yr −1, respectively.

서울시 대기 중 총 가스상 수은의 농도 및 특성 분석

The objectives of this study were to measure ambient TGM concentrations in Seoul Korea, to determine the temporal variation of TGM, and to analyze the relationships among TGM, meteorological data and PM2.5 measured at the same time. Ambient TGM and PM2.5 concentrations were measured at the roof of the Graduate School of Public Health building in Seoul, Korea for the period of January to October 2004. Average TGM concentration was <TEX>$3.43{\pm}1.17ng/m^3$</TEX>. The average TGM was at a low concentration similar to those of background sites in other countries. The temporal variations and meteorological phenomena of TGM were not statistically significant. There was a positive link between TGM and PM2.5. It didn't indicate that reduction of <TEX>$Hg^{2+}$</TEX> to Hg0 had occurred in liquid water contained in smog as in a previous study, but it shows that PM2.5 and TGM could be emitted from the same sources such as power plants and combustion engines. Also, the strong correlation between TGM and <TEX>$SO_2$</TEX> concentrations indicated that the source of TGM was from fossil fuel combustions including coal combustion. Specifically, <TEX>$SO_2\;and\;SO_4{^2-}$</TEX> concentrations correlated to TGM concentrations could be linked to TGM emitted from local and regional sources as well.