Forms Of Mercury Research Articles

Концентрирование ртути во взвешенном веществе пены и воды Чёрного моря

Способность взвешенного вещества концентрировать ртуть может быть превалирующим фактором в очищении водной толщи Чёрного моря. В результате седиментации взвешенные частицы выносят загрязнения из поверхностного слоя воды и в итоге могут депонировать их в донных осадках, участвуя таким образом в процессах самоочищения морской акватории. Взвешенное вещество как дисперсная фаза водной среды, рассматриваемой в качестве гетерогенной дисперсной системы, может быть более насыщено ртутью, чем сама вода как дисперсионная среда. В данной работе определён вклад растворённой и взвешенной форм ртути в её общее содержание и оценена концентрирующая способность взвешенного вещества в отношении ртути, обуславливающая биогеохимическое самоочищение вод от ртути. Все пробы воды разделяли на фильтрат и взвесь путём их фильтрации через нуклеопоровые фильтры с диаметром пор 0,45 мкм. Измерения содержания ртути проводили на анализаторе «Хиранума-1» методом атомно-абсорбционной спектрофотометрии. Концентрацию растворённой ртути в воде определяли в пересчёте на литр, а во взвешенном веществе — на литр и на грамм сухой массы. Выявлено превалирование растворённой формы ртути независимо от сезона года с варьированием её процентного содержания в диапазоне 66,3–85,8 % от общей (суммарной) концентрации ртути. Средняя концентрация взвешенной формы составила 14,2–33,7 % от её общего содержания. При этом значения концентрации взвешенного вещества (mвзв) варьировали от 0,1 до 15,0 мг·л−1 за весь исследованный период, а коэффициент накопления ртути взвешенным веществом (Кнвзв) изменялся в диапазоне от n·10³ до n·107. Определён значительный вклад взвешенной формы ртути в её общее содержание в морской пене, образованной в штормовую погоду. Так, при концентрации взвешенного вещества в морской воде 9,6 мг·л−1 концентрация растворённой формы ртути имела значение 55 нг·л−1, а взвешенной — 20 нг·л−1. В морской пене концентрация взвешенного осадочного вещества составила 895,2 мг·л−1, а концентрация ртути достигла 200 нг·л−1 в растворённой форме и 260 нг·л−1 — во взвешенной. Содержание общей (суммарной) ртути в морской пене при этом превышало предельно допустимую концентрацию (100 нг·л−1) для морской воды. В данном случае Кнвзв для морской воды был равен 3,8·104, а для пены — 1,5·103. Такое распределение ртути в морской взвеси, пене и воде, а также полученные значения коэффициента накопления свидетельствуют о большой важности взвешенного вещества в самоочищении морской акватории. При низком содержании ртути в воде концентрирующая способность взвешенного вещества, характеризуемая относительно высокими значениями его коэффициента накопления ртути, становится весьма значимым фактором в седиментационном самоочищении вод от ртути, однако при повышении загрязнения вод ртутью влияние этого фактора снижается.

Presence of mercury and methylmercury in Baltic Sea sediments, collected in ammunition dumpsites

Methylmercury (MeHg) is the most toxic and dangerous form of mercury occurring in the environment. MeHg is highly bioaccumulative in organisms and undergoes biomagnification via the food chain. In the Baltic Sea munition dumpsites, methylmercury can be formed from mercury fulminate contained in primary explosives, as environmental conditions there favour methylation. MeHg in analysed sediments ranged from 19 to 2362 pg g−1d.w., the concentration of mercury (HgTOT) ranged from 4 to 294 ng g−1 d.w., and the values of MeHg/Hg ratio ranged from 0.1 to 2.0%. The obtained results confirmed that munition dumpsites are a source of mercury. The concentration of MeHg is elevated in a wider area than immediately next to dumped munitions. Presented results suggest that physical processes responsible for sediment and near-bottom water movement are diffusing MeHg signal, making munition dumpsites rather a diffuse source of MeHg than a number of point sources associated with particular munitions.

In vitro spore germination and phytoremediation of Hg and Pb using gametophytes of Pityrogramma calomelanos

Few pteridophytes have proven the capacity to accumulate and remediate heavy metals from contaminated soils. Pityrogramma calomelanos, a non-seasonal fast-growing, a cosmopolitan fern, is a good indicator of environmental conditions, was used in the present study. The life cycle of ferns alternates with haploid gametophyte and diploid sporophyte. The present study was undertaken to access the effect of mercury, in form of mercury (II) chloride [(HgCl2)] and lead as lead nitrate [Pb(NO3)2] in developmental studies using in vitro spore germination. Periodic recording of the germination, protonemal growth, rhizoid formation and differentiation of sex organs in different concentrations of heavy metals were conducted for a period of 6 weeks. It was found that the percentage of spore germination and the number of protonemal cells reduced significantly causing developmental defects in the presence of HgCl2 as compared to Pb(NO3)2 (p < 0.0001). A significant decrease in the number of archegonial count and chlorophyll content was observed in different concentrations of the heavy metals tested. Gametophytes of P. calomelanos recorded lead uptake of 646.51 ± 0.93 mg/kg in treatments of 25 ppm of lead and high mercury accumulation up to 1,885 ± 1.98 mg/kg at 10 ppm of mercury, indicating successful uptake of heavy metals. Novelty statement: Pityrogramma calomelanos is gaining interest amongst pteridologists upon proving its exclusive capacity of phytoremediation. It is superior in comparison to the most popular, patented fern Pteris vittata. Our study demonstrates the effective use of the promising fern in its simplest, nonvascular form of gametophytes as a phytoremediation agent in controlled conditions.

Variation in the Content of Different Forms of Mercury in River Catchments of the Southern Baltic Sea – Case Study

Abstract Mercury (Hg) is recognised as a global environmental pollutant. Despite numerous studies being conducted around the world, the transformation of mercury in natural environments is still not fully understood. In addition, increasing droughts and heavy rains are currently observed to contribute to changes in the circulation of Hg. The purpose of this study was to recognise the influence of extreme meteorological and hydrological conditions on the inflow of various forms of mercury to the coastal zone of the Bay of Puck. The studies were carried out at estuarial stations of four rivers belonging to the southern Baltic Sea catchment: Reda, Zagorska Struga, Gizdepka and Płutnica. The results showed that meteorological and hydrological parameters affect mercury speciation in river catchments, which translates into inflow of labile mercury to the southern Baltic Sea.

Production of methylmercury by sulphate-reducing bacteria in sediments from the orbetello lagoon in presence of high macroalgal loads

Methylmercury is a potent neurotoxin affecting shallow-water ecosystems. Mercury polluted sediment samples were collected at six different sites in the Orbetello Lagoon (central Italy) characterized by high levels of silt, iron, manganese hydroxides, and organic matter originated the latter originated from the decomposition of macroalgae. Porous water pointed out the presence of sulphates, methylmercury, and sulphides. Slurries arranged in anaerobic conditions from sediment aliquots from the six sites, with the addition of ionic mercury, highlighted the production of methylmercury. Sulphate reducing bacteria (SRB) were quantified in lagoon sediments; furthermore, sediments cultured under anaerobic conditions showed SRBs active in mercury methylation. Anaerobic cultures of SRB, amended with ionic mercury, produced methylmercury during the growth of bacterial cells. The percentage of aerobic mercury resistant bacteria was pointed out at each sampling site, evidencing the presence of bioavailable mercury. Several aerobic mercury resistant bacteria were isolated and their level of resistance to inorganic and organic forms of mercury was evaluated. These isolates may be potentially used for eventual bioremediation processes. Mercury methylation by SRB in the Orbetello Lagoon sediments was described for the first time, focusing the attention on the need for possible bioremediation processes by using autochthonous mercury resistant bacteria. Moreover, the influence of algal biomass on mercury methylation was highlighted for the first time in this lagoon ecosystem. The importance of removing algal biomass, as it represents a source of organic matter favouring the process of mercury methylation, was strongly pointed out in this study.

Mercury Thermoforms and Their Distribution in the Sedimentary Sequence of the Juan De Fuca Ridge

This paper addresses the vertical distribution of total mercury and its thermoforms in the Holocene–Upper Pleistocene sedimentary rocks from the Dead Dog active hydrothermal field in the Middle Valley, Juan de Fuca Ridge, Pacific Ocean. Sediment samples were taken from the core of Hole 858B drilled during ODP leg on the top of a sulfide hill, in a zone of ascending hydrothermal fluid, in the vicinity of high-temperature vent with temperature of 276°С. The contents of mercury and its thermoforms were measured by atomic absorption spectrometry (AAS) with thermal atomization. The highest mercury concentrations in the sediments reach 10.3 μg/g. Mercury is present in sediments in the following thermoforms: free mercury (FR), chloride (ChL), physically sorbed (PhS), chemically sorbed (ChS), sulfide (SF), and isomorphic (IS) forms. In the sedimentary section, contrasting concentrations of mercury alternate like a “layer cake” due to its accumulation at geochemical barriers.

Regulation of Single-Channel Conductance of Voltage-Dependent Anion Channel by Mercuric Chloride in a Planar Lipid Bilayer.

The existence of mercury in various forms, e.g., elemental, organic, and inorganic has been known for decades. In any of these forms, it is poisonous to metabolism. In this, an investigation about the effect of the inorganic form of mercury, i.e., mercuric chloride (HgCl2) to the mitochondrial voltage-dependent anion channel (VDAC), has been done after isolation from the cardiac and brain tissues of Wistar rats. In vitro electrophysiology experiments were performed in Cardiolipin planar lipid bilayer membrane (BLM) to study the change in the conductance, selectivity, and gating charge of VDAC post HgCl2 treatment. A reduction in mean conductance of VDAC from 4.3 ± 0.18 to 1.66 ± 0.11 nS was observed. Further, the Gating charge calculated before (± 3.5) and after HgCl2 treatment (± 2.3) showed significant difference. Later, VDAC's behavior was studied at different concentrations of HgCl2 ranging from 0.1μM to 1mM. The Inhibitory concentration (IC50) was calculated from the linear regression plot. The IC50 was found to be 488.1μM. In the asymmetrical HgCl2 (5:1), a permeability ratio of cation to anion was found to be 4.2. It is interpreted that VDAC functioning is affected due to the application of 4mM HgCl2 and a reduction in the conductance, gating charge, and permeability of VDAC was detected. The results provide clues to HgCl2-induced toxicity mediated through VDAC in the Cardiolipin BLM.

Mercury in the sediments of freshwater lakes in Ny-Ålesund, Arctic.

Mercury and its speciation in aquatic ecosystems have been assessed globally. Even though previous studies were limited to Arctic freshwater lakes, they are highly significant in the context of the changing climate. The present study is based on sediment samples collected from three Arctic freshwater lakes over a period of 4years (2015-2018). The samples were analysed for total mercury (THg), methyl mercury (MHg), and various mercury fractions. The observed mean THg and MHg concentrations were 22.23ng/g and 0.41ng/g respectively; these values were comparable with those for other Arctic freshwater lakes. The mercury content significantly varied among the years as well as among the lakes. Changes in snowdrift and meltwater inputs, which are the major sources of water for the lakes, may have influenced the sediment mercury content along with geographical location and increased productivity. The results of MHg indicated the susceptibility of lake sediments to methylation. The major fractions observed were the organo-chelated form of mercury, followed by the elemental and water-soluble forms. These results indicate the availability of mercury for methylation. Hence, it is necessary to conduct more studies on the influence of climate change, mercury release through permafrost melting, and atmospheric deposition.

Articles of Significant Interest in This Issue

Geothermal systems emit significant quantities of mercury into the environment. Gionfriddo et al. (e00176-20) present a new conceptual model, supported by metagenomics and detailed geochemistry, of the environmental factors controlling the fate of mercury in warm springs. This model accounts for changes in mercury form, microbial interactions with mercury, and the mobility of toxic mercury. It also yields new insights into biogeochemical links among the mercury, sulfur, and iron cycles, providing a framework for studying natural geothermal mercury sources globally.

Preliminary Study on Human Lung Function of Artisanal and Small-scale Gold Miner in Gorontalo Province, Indonesia

Effects of mercury from ASGM in humans have been reported in various studies. The effect depends on the dose, the form of mercury, and a way of entering the body. The human body with all its perfection has a remarkable system of defense against external negative effects including toxic effects of mercury. One of the leading defense systems of the human body is the respiratory system, because it is an organ connected directly to the outside environment. Early detection is very necessary to prevent the incidence of more severe, then the initial lung examination is needed and important. For that, there needs to be an examination of the lungs that can be used to find early lung disorders, namely the spirometry test. During this time in each study was only performed blood tests, urine and hair to assess the levels of mercury, but the disease-based examination is limited to only a neuropsychological examination. Spirometry is useful and basic in the diagnosis of lung diseases. In addition to assessing respiratory function primarily assessing breathing pattern, such as pulmonary fibrosis or asthma, it is also very helpful in health surveillance. In the preliminary survey, 4 samples were taken consisting of 2 miner samples and 2 samples non-miners (control). These 4 sample have the same age range, with the same smoking status. The spirometry test result shows that all miner had lung disorders and control samples had normal results. The conclusions from this survey are: (1) Mercury pollution must be a serious attention for all of us; (2) all miners tend to be exposed to evaporated mercury; (3) Spirometry tests can be one of the health examinations for early detection of lung disease.

Mercury emission from the aluminium industry: a review

There has been a rising global concern of mercury because of its persistent nature, long-range transport and toxicity. Mercury possesses serious health effects on living organisms and the environment. Mercury, mostly in inorganic form, is present in almost all categories of rocks. It may be released through natural occurrences and/or anthropogenic activities such as aluminum production. Stable organic mercury compounds, for example methyl mercury (CH3Hg), are formed by the attachment of mercury to one or two carbon atoms. Depending on the source of bauxite, a substantial amount of elemental mercury is released by aluminum industries. Emitted elemental mercury contributes to increasing global atmospheric reserve of mercury hence decreasing mercury emissions plays a key role in lowering the contribution of anthropogenic activities to the global atmospheric mercury budget. In general, all three forms of mercury (elemental, inorganic and organic mercury) have the potential of causing adverse health effects at sufficiently high doses. Mercury emissions are readily absorbed through the alveoli membranes and gastrointestinal tract affecting other systems. Fetuses and individuals often exposed to mercury (chronic exposure) are two classes of people who are more susceptible to harm caused by mercury. This paper discusses mercury metal and oxide emission from the aluminum industry.

Distribution of chemical forms of mercury in sediments from abandoned ponds created during former gold mining operations in Colombia

Total mercury (THg) and methylmercury (MeHg) were studied in sediments from 27 abandoned gold mining ponds (AGMPs) through small-scale artisanal gold mining in the district of San Juan in Chocó region of Colombia. The AGMPs were abandoned in the last century (1997) and were grouped into three distinct groups (2–6; 7–12; 13–20 years). Overall concentration (in ng g−1) pattern of THg in sediments varied from 39.06 to 1271.32 (avg. 209.57) with 174.81 (13–20 years), 205.56 (7–12 years) and 248.33 (2–6 years) respectively. MeHg concentrations accounted for 3.3–10.9% (avg. 6.5%) of THg and were significantly correlated with THg during all periods. Correlations between organic matter (OM) vs MeHg and THg were negative in the oldest pools, signifying a “dilution effect” or “natural burial” of THg and MeHg. Results for sequential extraction indicate that the fraction of elemental Hg (Hg-e) and organo chelated Hg (Hg-o) represent the main chemical forms of Hg in the sediments, regardless of the abandonment period, whereas the bioavailable fraction was only 0.12–1.65% of THg. The significant statistical relationship between MeHg, THg and OM suggests that these parameters control the distribution, mobility, toxicity and bioavailability of Hg in the sediments of these abandoned ponds. Evaluation of THg with sediment quality guidelines indicates that the values are on the higher side for Threshold effect concentration and Upper continental crust. Comparing of MeHg with many other regions outside Colombia is a worrying factor and needs immediate attention to protect the human health.

Cyanide Contamination of the Puyango-Tumbes River Caused by Artisanal Gold Mining in Portovelo-Zaruma, Ecuador.

To examine cyanide (CN-) contamination of a large river in southeastern Ecuador that has been severely impacted by the indiscriminate discharge of untreated gold processing effluents. Poor environmental stewardship of cyanide (CN-) use by 87 gold processing centers in Portovelo-Zaruma in southern Ecuador to leach residual gold from Hg-contaminated tailings has resulted in high CN- contamination of the Puyango-Tumbes River downstream from the centers. Free CN- concentrations were high in river surface waters for 50km below the processing plants, with the highest concentration 9088 times above the CCME standard of 5μg/L and 1136 times above the 24-h LC50 concentration of 40μg/L free CN- for some fish species. Due to cyanidation of mercury-contaminated tailings, the formation of Hg-CN complexes is a grave concern, as these complexes have been shown to be highly bioavailable. Preliminary tests conducted in a laboratory using bioassays with Danio rerio sp. and varying concentrations of synthetic Hg(CN)2 salt have shown significant THg bioaccumulation in muscle and kidney fish tissues exposed to concentrations >0.12mg/L. Furthermore, low MeHg results in fish tissues demonstrated little occurrence of methylation and that the bulk of the total mercury content was in the form of inorganic mercury. Although construction of a communal tailings facility (CTF) in Portovelo is a positive development to reduce riverine pollution, the requirement to truck tailings up to the CTF likely results in inadequate compliance of environmental regulations that are poorly enforced.

Mercury and its effect on human health: a review of the literature

Mercury in human body is a free radical that can cause depletion of glutathione (GSH) and hoarding of H2O2, leading to shorten the age of erythrocytes and cause haemolysis. Approximately 90% organic form can be absorbed by the intestinal wall, while inorganic forms are only about 10%. The initial form can also penetrate the blood and placental barrier so that it can cause teratogenic effects and nervous disorders. The effects of mercury toxicity on humans depend on the chemical form of mercury, dosage, age of people exposed, length of exposure, entry into the body, fish diet and consumption of seafood. Mercury is able to bind sulfidril proteins in cells resulting in nonspecific cell injury or even cell death, cessation of microtubule formation, enzyme inhibition, oxidative stress, cessation of protein and DNA synthesis, and autoimmune responses. Classified into a very toxic metal, mercury can trigger the formation of ROS, hydrogen peroxide, lipid peroxidation, hydroxyl radicals that can inhibit enzymes, cell damage, DNA damage, protein structure damage, disruption on the body's antioxidant metabolism, especially superoxide dismutase (SOD) and glutathione peroxidase (GPx). Mercury exposure is associated with an increased risk of hypertension, myocardial infarction, coronary dysfunction, and atherosclerosis. This review is clearly in line to investigate the effect of mercury on human health based on previous research, article and other literature sources.

Fractionation of mercury in aerosols of the southern Baltic coastal zone

Abstract The form in which Hg occurs in the atmosphere is important to understand the toxicity and bioavailability of this metal. So far, research on mercury speciation in the atmosphere has mostly focused on its three forms: elemental gaseous mercury (GEM/Hg0), reactive gaseous mercury (GOM/Hg2+) and mercury bound in aerosols (TPM). However, these studies do not provide complete information on mercury compounds in aerosols. Only a few publications on mercury fractionation in TPM have been published, but these have focused mainly on describing the method and have provided only a limited number of environmental results. Therefore, the research aimed to identify forms of mercury occurring in aerosols in the coastal zone of the southern Baltic Sea, as well as to determine factors affecting the temporal changes in the share of individual Hg fractions. Aerosol samples were collected in Gdynia (Poland) from May 2016 to January 2017. A thermo-desorption technique was used for the determination of total mercury and Hg fractions. Mercury in aerosols was present mainly in labile factions related to mercury halides, mercury nitrate and organic mercury as well as gaseous mercury. The stable Hg fraction, mainly bound to Hg sulphide, constituted only 7% of total particulate mercury. The conducted research also allowed to determine the origin of mercury sources in aerosols. In the winter it was burning of fossil fuels, and in the summer biological activity and emission from the sea.

Raman reporter-assisted Au nanorod arrays SERS nanoprobe for ultrasensitive detection of mercuric ion (Hg2+) with superior anti-interference performances

Ultra sensitive detection of mercuric ion (Hg2+) with superior anti-interference capability from natural water is of great significance for food safety, environmental protection, and human health. We herein develop Au ordered nanorod arrays (Au NRAs) as surface-enhanced Raman scattering (SERS) substrates to construct SERS-active and signal-reproducible sensing platforms modified with 4-mercaptophenylboronic acid (4-MBA) as multifunctional SERS reporters. The aqueous Hg2+ can be efficiently trapped by 4-MBA through electrophilic substitution reactions and precisely appraise its concentration based on the collective spectral changes of reporters including peak disappearance, emergence, and Raman shift. Based on this, the optical nanoprobe shows an ultrahigh detection sensitivity of 0.1 nM for Hg2+, which is two orders of magnitude lower than the U.S.A. environmental protection agency (EPA)-required maximum level of drinkable water. It also offers both an exceptional Hg2+ discrimination against other metal ions as well as organic ligands and perfect feasibilities of detecting solutions with ultra-wide pH ranges from 1.0–14.0 at varying temperatures. Moreover, the nanoprobe demonstrates an ability to identify different chemical forms of mercury and has a high repeatability, accuracy and reliability to meet the practical detection requirements in natural environments.

Keratinous biomarker of mercury exposure associated with amyotrophic lateral sclerosis risk in a nationwide U.S. study

Objective: The majority of cases of the fatal neurodegenerative disease amyotrophic lateral sclerosis (ALS) are of unknown etiology. A proportion of these cases are likely to be attributable to contaminant exposures, although the specific environmental etiology of ALS remains largely a mystery. Certain forms of the neurotoxic metal mercury readily cross into the central nervous system. Fish is a dietary source of methylmercury, but also of beneficial components, such as omega-3 polyunsaturated fatty acids. Prior work using clinic-based studies of toenails and hair as keratinous biomarkers of exposure suggest elevated mercury levels in ALS patients compared with controls. We sought to validate this relationship in a U.S. case-control comparison of mercury levels in nail clippings. Methods: We performed trace element analysis using inductively coupled plasma mass spectrometry (ICP-MS) on the nail clippings of n = 70 female, geographically representative ALS patients from the National ALS Biorepository and compared them to n = 210 age-matched controls from a set of n = 1216 nationally distributed controls from the Sister and Two Sister Studies. Results: Compared to the lowest quartile of nail mercury, moderate levels were associated with decreased risk of ALS (P = 4.18e–6). However, the odds of having nail mercury levels above the 90th percentile were 2.3-fold higher among ALS patients compared with controls (odds ratio (OR) = 2.3, 95% confidence interval 1.10–4.58, adjusted for age and smoking status). Conclusion: This finding suggests that excessive mercury exposure may be associated with the neurodegenerative health of aging populations.

Biofilms grown in aquatic microcosms affect mercury and selenium accumulation in Daphnia

Experiments examining mercury (Hg) toxicity in Daphnia are usually conducted in highly standardized conditions that prevent the formation of biofilm. Although such standardization has many advantages, extrapolation of results to natural conditions and inference of ecological effects is challenging. This is especially true since biofilms can accumulate metals/metalloids and play a key role in their transfer to higher trophic level organisms. In this study, we experimentally tested the effects of spontaneously appearing biofilm in Daphnia cultures on accumulation of Hg and its natural antagonist selenium (Se) in Daphnia magna. We added Hg (in the form of mercury (II) chloride) at two concentrations (0.2 µg/L and 2 µg/L) to experimental microcosms and measured the uptake of Hg and Se by D. magna in the presence and absence of biofilm. To test for consistent and replicable results, we ran two identical experimental sets one week apart. Biofilm presence significantly reduced the accumulation of Hg, while increasing the tissue Se content in D. magna, and these findings were reproducible across experimental sets. These findings indicate that highly standardized tests may not be adequate to predict the bioaccumulation and potential toxicity of metals/metalloids under natural conditions.

Determination of mercury binding forms in humic substances of lignite

Mercury is known for primarily binding organically in lignite and inorganically in coal. The knowledge about the binding forms does not impact the speciation of mercury in the combustion chamber of a power plant. However, the relation between binding forms and release behavior is crucial for modelling the material flow of mercury in the firing process. Oxidizing agents like halogen salts could be added more effectively. There are different analyzing methods like the float-sink-analysis or the sequential leaching to determine the mercury binding forms. Nevertheless, there is no standard procedure for each analyzing method, which allows a comparison. In this work, mercury binding forms in Central German lignite were investigated. Results from thermal treatment of the lignite show a loss of mercury of 87% up to a temperature of 200 °C. The responsible mercury binding form for that release behavior is discussed by using the results of a leaching process for the extraction of humic substances, mercury analyses and simultaneous thermal analyses with mass spectrometry (TG/DSC-MS). The results show that mercury is bound to humic acids with 0.261 mg/kgdry and in humin with 0.735 mg/kgdry. The high mercury affinity of humic substances is noted as the result of chemical binding with functional groups like the carboxyl group, hydroxyl group and thiol group. Compared to the raw sample, a thermally treated lignite (at 200 °C) does not show any thiol group (m/z=48) in ion intensity measurement. This work proves the organic binding form of mercury with humic substances in lignite.

Simulation of atmospheric mercury dispersion and deposition in Tehran city

In this study, dispersion and deposition of atmospheric mercury (Hg) in Tehran city was simulated using WRF-SMOKE-CMAQ models. The Weather Research and Forecasting (WRF) model was used to simulate the meteorological parameters. For validation of WRF results, the simulated wind speeds and temperatures were compared with the parameters measured at a meteorological station in Tehran city for 11 days (8 days in fall and 3 days in winter) in 2010–2011. The correlation coefficient (r) for temperature and wind speed was 0.94 and 0.49, respectively, indicating there was good agreement between measured and modeled results. An atmospheric mercury emission inventory was developed using the United Nations Environment Programme (UNEP), the United States Environmental Protection Agency AP-42 (US-EPA AP-42), and related papers. Sparse Matrix Operator Kernel Emissions (SMOKE) was used to allocate the atmospheric mercury emissions to the modeling domain, and the Community Multiscale Air Quality (CMAQ) model was used to simulate the concentration and deposition of atmospheric mercury. To validate the results of the CMAQ model, the simulated atmospheric particulate mercury (PHg) concentrations for 11 days were compared with the measured results at two different stations (Bagh Ferdows and Bahman Square) where it was measured by the Tehran Air Quality Control Company (AQCC). Comparison between the results from the modeled and measurements of PHg in fall was better than winter. Concentrations and dry depositions of the various forms of atmospheric mercury were higher in areas closer to mercury stationary emission sources.