Total arsenic, lead, cadmium, copper, and zinc in some salt rivers in the northern Andes of Antofagasta, Chile

Lake Velenje is located in one of the most polluted regions in Slovenia, the Salek Valley. The major source of pollution in the valley is the coal-fired thermal power plant in Sostanj (STPP, capacity 775 MW). It has five separate units. All units have electrostatic precipitators for fly ash removal. Unit 4 also has installed a wet flue gas desulfurisation system (FGD system). Total mercury (THg) concentrations were measured in lignite, slag and ash samples from the STPP. In flue gas, different mercury species (THg, MeHg, Hg2+, Hg0) were determined separately for unit 4 and unit 5 which use different flue gas cleaning technology. Mercury and methyl mercury (MeHg) concentrations were also measured in lake water at different depths, in inflow water, outflow water, rain, snow and lake sediments in order to establish the influence of the power plant on the lake. Most mercury emitted from the power plant is in the elemental form. The ratio between oxidised and elemental Hg depends on the flue gas cleaning technology. Mass balance calculations have been performed for the STPP. The results show that the major sources of mercury in Lake Velenje are wet deposition and lake inflows. Total and MeHg concentrations in the water column are very low and can be compared to other non-contaminated freshwater lakes in the world.     

Emissions of mercury and other trace elements from coal-fired power plants in Japan

To evaluate trace element emissions from modern coal-fired power plants into the atmospheric environment in Japan, trace elements in the coal used in electric utility boilers, stack concentrations, emission rates and emission ratios of coal-fired power plants, and proportions of trace elements in coal-fired power plants were studied. The elements were As, B, Be, Cd, Co, Cr, F, Hg, Mn, Ni, Pb, Sb, Se and V, which are designated in the Law of Pollutant Release and Transfer Register. The particulate trace elements were collected in an electrostatic precipitator and a wet desulfurization scrubber. Emissions into the atmosphere were lower than 1% of the quantity in coal, but the volatile trace elements showed somewhat higher emission ratios. For mercury, the mean concentration in coal was 0.045 ppm, the mean emission rate was 4.4 microg/kW h, and the mean emission ratio was 27%, the highest ratio among all elements in this study. The total annual emission of mercury from coal-fired power plants of the electric power industry in Japan was estimated to be 0.63 t/y. On the basis of these data, the atmospheric environment loads from a coal-fired power station were investigated. The calculation of stack gas dispersion showed that maximum annual mean ground level concentrations were in the order of 10(-2) to 10(-5) of the background concentrations, and that the adverse effect of the emissions from the coal-fired power station was small.     

Evaluation on speciation and removal efficiencies of mercury from municipal solid waste incinerators in Taiwan

Two large-scale municipal solid waste incinerators (MWIs) located in Taiwan were selected for conducting flue gas sampling to determine the chemical speciation of mercury by both USEPA Method 29 and Ontario Hydro Method (OHM). In addition, the emission characteristics and removal efficiencies of mercury were evaluated via isokinetic sampling of flue gas upstream and downstream of APCDs. Results indicated that the average removal efficiencies of Hg for MWI-A and MWI-B were 29.56 and 44.70%, respectively. In terms of mercury speciation by USEPA Method 29 and Ontario Hydro Method (OHM), oxidized mercury (Hg2+), in the flue gas was predominant at the inlet of APCD for both incinerators. Less than 30% of mercury in the flue gas existed in the elemental form (Hg0) at APCD inlet. Mercury emitted from the stack also predominated as a form of Hg2+ in MWI-A. Approximately 90% of total mercury emission from the stack existed in the form of Hg2+ for MWI-A. Due to the higher removal efficiency of soluble mercury (Hg2+) in wet scrubber, less total Hg was actually emitted from MWI-B than MWI-A. Regarding the removal efficiency of Hg0 in the flue gas, the APCDs of MWI-A (DSI + FF) had a higher removal efficiency than that of MWI-B (ESP + WS) possibly due to the reduction of Hg2+ which occurred in the wet scrubber.     

Mercury emissions from selected stationary combustion sources in Korea

Mercury emissions from various stationary combustion sources such as coal-fired power plants, oil-fired power plants, industrial utility oil boilers, iron manufacturing plants, and industrial waste incinerators, were measured. The US EPA (Environmental protection agency) method 101A and the Ontario hydro method were used to sample the mercury containing combustion flue gases, at the inlet of the air pollution control devices (APCDs) and at the stack. Collected samples of both gaseous and particulate forms were then analyzed using CVAA (cold vapor atomic absorption) type analyzer. Measurement results from the coal-fired power plant showed percentages of elemental mercury (Hg0) as high as 31.4% and as low as 9.5%. However, the content of Hg0 was in the range of 1.3-3.7% from the industrial waste incinerator. Differences in mercury speciation from various stationary combustion sources are believed to be coming from: (1) difference in the fuel types; (2) difference in the major flue gas compositions (ex. HCl and SOx); and (3) difference in the types of air pollution control devices (APCDs). When the measurement results obtained using different sampling methods were compared, the Ontario Hydro Method gave a slightly higher mercury concentration measurement than that of the US EPA Method 101A.     

影响燃煤电厂除尘器选择的定量研究

通过对200个电厂的不同煤质和飞灰成分进行偏相关分析,得出了影响电除尘器除尘难易性的关键因素,通过多元回归分析,获得燃煤电厂采用湿法烟气脱硫执行不同烟尘排放标准30mg／m^3和20mg／m^3时的除尘器选型方法,并对选型方法的准确率和涵盖率进行了验算,以供参考。     

Mercury in coal ash and its fate in the Indian subcontinent: A synoptic review

In the Indian subcontinent power generation is mainly dependent upon the thermal power units and coal is burnt as a fuel for the production of heat and electricity. In India, bituminous and sub-bituminous coals are used which contain over 40% of ash. At present, 80-90 million tons of fly ashes are generated from 85 existing coal based thermal power plants. Coal contains trace metals of which mercury is most toxic for humans and aquatic fauna. The problem of mercury in the society is not new, but in recent years the Indian subcontinent has gained the reputation of being "a dumping ground for mercury". This study focuses on mercury in fly ash and its releases to the atmosphere and soils cross the country. The utilisation of coal ash in India is also addressed although it is still in its nascent stage. About 10% of produced fly ashes are used in India whereas in Western countries its use is typically over 70%. Regulations from India's Ministry of Environment and Forestry should increase coal fly ash utilisation, although this would require that cost-effective new technology is put to use. As to the release of Hg from ashes disposed of in the environment, the scarce literature suggests that this is negligible or zero, and less problematic than wet or dry deposition of Hg from flue gases.     

Atmospheric emissions estimation of Hg, As, and Se from coal-fired power plants in China, 2007

Over half of coal in China is burned directly by power plants, becoming an important source of hazardous trace element emissions, such as mercury (Hg), arsenic (As), and selenium (Se), etc. Based on coal consumption by each power plant, emission factors classified by different boiler patterns and air pollution control devices configuration, atmospheric emissions of Hg, As, and Se from coal-fired power plants in China are evaluated. The national total emissions of Hg, As, and Se from coal-fired power plants in 2007 are calculated at 132 t, 550 t, and 787 t, respectively. Furthermore, according to the percentage of coal consumed by units equipped with different types of PM devices and FGD systems, speciation of mercury is estimated as follows: 80.48 t of Hg, 49.98 t of Hg²⁺, and 1.89 t of Hg^P, representing 60.81%, 37.76%, and 1.43% of the totals, respectively. The emissions of Hg, As, and Se in China's eastern and central provinces are much higher than those in the west, except for provinces involved in the program of electricity transmission from west to east China, such as Sichuan, Guizhou, Yunnan, Shaanxi, etc.     

Mercury emissions from coal-fired power stations: The current state of the art in the Netherlands

About 30% of the electricity produced in the Netherlands is generated by coal, all of which is imported. At the same time, the co-combustion of biomass is becoming increasingly important. For the last 25 years, the fate of the elements/trace elements in general and of mercury in particular has been studied in great detail. It appears that on average 50% of the mercury is removed in the ESP (particulate control) and 50% of the remainder is removed in the flue gas desulphurization (FGD), resulting in a total mercury removal of 75%. If a high dust selective catalytic reduction (SCR for NO(x) reduction) is present, the total removal can be up to 90%. The results indicate that on average the removal of mercury during the co-combustion of biomass is similar to that found for full coal-firing. The conclusion is that a modern coal-fired power station with the above-mentioned flue gas cleaning equipment also removes mercury up to 90%. These cleaning devices are being installed to reduce the emission of particulates, sulphur dioxide and nitrogen oxides. This means that mercury abatement can be increased while meeting the EU regulation for SO(2) and NO(x). The application of Best Available Technique (BAT) for coal-fired installations by 1-1-2008 will lead to a further increase in the construction and operation of FGD and DeNO(x) installations.     

The distribution, occurrence and environmental effect of mercury in Chinese coals

Mercury (Hg) is a toxic, persistent, and globally distributed pollutant due to its characteristic properties such as low melting and boiling points, conversion between chemical forms and participation in biological cycles. During combustion mercury in coal is almost totally emitted to the atmosphere. With a huge amount of coal consumed, coal combustion is one of the main anthropogenic sources of this element in the environment. In this study, Hg data of 1699 coal samples of China has been compiled, and the concentration, distribution, modes of occurrence, and the impact of Hg emissions on the environment are investigated. Most Chinese coals have Hg content in the range of 0.1 to 0.3 ppm, with an average of 0.19 ppm, which is slightly higher than the average Hg content of world coals and is close to that of the U.S. coals. The Hg content in coals varies in different coal basins, geological ages and coal ranks. The most likely mode of occurrences of Hg in high-sulfur and high Hg content coals is as solid solution in pyrite. But in low-sulfur coals, modes of occurrence of Hg are variable, and the organic-bound and sulfide-bound Hg may dominate. Silicate-bound Hg may be the main form in some coals because of magmatic intrusion. Mercury emissions during coal combustion have resulted in serious environmental contamination in China, particularly in the northeastern and southwestern China, where a high Hg content in the atmosphere occurs.     

Emission of polycyclic aromatic hydrocarbons from animal carcass incinerators

This study investigated two batch-type animal carcass waste incinerators, one in a hog farm (HOWI) and the other in a livestock disease control centre (LIWI). Additionally, a medical waste incinerator (MEWI) with a fixed grate for the disposal of biological medical waste was also examined. A GC/MS technique was applied to analyze the concentrations of 21 polycyclic aromatic hydrocarbons (PAHs) species in the stack flue gas, bottom ash and wet scrubber (WSB) effluent. The analytical results indicated that total-PAHs in the stack flue gas for HOWI, LIWI and MEWI were mainly in the gaseous phase. Moreover, the mean total-PAHs concentrations of the stack flue gas for HOWI and LIWI were 1.5 and 1.4 times higher than for MEWI (=391 microg/m(3)), respectively. At the most carcinogenic potencies, the results revealed that the mean BaP+BbF+DBA concentrations in the stack flue gas for HOWI and LIWI were 7.6 and 4.6 times higher than those of MEWI (=1.18 microg/m(3)), respectively. Moreover, during the outbreak of foot-and-mouth disease among pigs in southern Taiwan in 1997, emissions of total-PAHs and BaP+BbF+DBA exceeded 226.2 and 2.3 kg/day, respectively.     

燃煤电厂烟气中汞形态及含量的采样分析方法

分析燃煤电厂烟气中汞的形态分布,探讨烟气中汞形态及含量的采样分析方法,对各种采样分析方法的特点进行了比较。     

Atmospheric mercury deposition in Guizhou, China

The atmospheric deposition of mercury including total gas phase mercury (TGM), gas phase divalent mercury (Hg2+), and gas phase monomethyl mercury (MMHg) was investigated. Samples were collected from central cities and nature reserve areas across the province. Techniques and equipment including moss bags, KCl-coated denuder and GARDIS-1A portable mercury vapor analyzer were employed for sample collection and analysis. The reliability of techniques and analytical methods used for the project was evaluated. The deposition of atmospheric mercury was reported in species in this important mercury polluted province for the first time. The spatial and temporal variability of mercury emissions were investigated and reported. Contribution of coal mercury emissions to the atmosphere mercury deposition of the province was also investigated.     

Spatial distribution and temporal variation of metals in the vicinity of a municipal solid waste incinerator after a modernization of the flue gas cleaning systems of the facility

In June 1994 and 1997, the concentrations of a number of elements were determined in soil and herbage samples collected in the vicinity of a municipal solid waste incinerator (MSWI) (Tarragona, Catalonia, Spain). In August 1997, an adaptation to the EU legislation on pollutant emissions from the stack was carried out to the incinerator. In June 1999, soil and herbage samples were collected again at the same sampling points and the levels of arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), manganese (Mn), mercury (Hg), nickel (Ni) and vanadium (V) were measured by ICP-MS or AAS with graphite furnace. The results are compared with those obtained in the 1994 and 1997 surveys. In the period 1997-1999, the only significant changes in soil levels corresponded to Cd and Pb, with decreases of 21.0% and 53.5%, respectively. In vegetation, only Mn levels showed a significant reduction, which contrasts with the notable increases found in the concentrations of As, Hg and Ni. According to the results of this survey, it seems evident that other metal emission sources in the same area of study are masking the environmental improvements carried out in the MSWI.     

Mercury emissions to the atmosphere from anthropogenic sources in Europe in 2000 and their scenarios until 2020

The paper reviews the current state of knowledge regarding European emissions of mercury and presents estimates of European emissions of mercury to the atmosphere from anthropogenic sources for the year 2000. This information was then used as a basis for Hg emission scenario development until the year 2020. Combustion of coal in power plants and residential heat furnaces generates about half of the European emissions being 239 tonnes. The coal combustion is followed by the production of caustic soda with the use of the Hg cell process (17%). Major points of mercury emission generation in the mercury cell process include: by-product hydrogen stream, end box ventilation air, and cell room ventilation air. This technology is now being changed to other caustic soda production technologies and further reduction of Hg emissions is expected in this connection. The third category on the list of the largest Hg emitters in Europe is cement production (about 13%). The largest emissions were estimated for Russia (the European part of the country), contributing with about 27% to the European emissions, followed by Poland, Germany, Spain, Ukraine, France, Italy and the United Kingdom. Most of these countries use coal as a major source of energy in order to meet the electricity and heat demands. In general, countries in the Central and Eastern Europe generated the main part of the European emissions in 2000. Emission reductions between 20% and 80% of the 2000 emission amounts can be obtained by the year 2020, as estimated by various scenarios.     

Emissions from power plants fueled by peat,coal, natural gas and oil

Measurements were carried out to investigate the emissions of SO₂, NO_x, fly ash, heavy metals, radioactive elements and polycyclic aromatic hydrocarbons (PAH) from one oil-fired, two coal-fired, five peat-fired and four natural gas-fired power plants or district heating plants.The emissions of sulphur dioxide depended mainly on the sulphur content of the fuel. In the combustion of oil, practically all the sulphur in the fuel reached the atmosphere as sulphur dioxide. When coal and peat were used as fuel, the amounts of sulphur retained in the ash were about 15 and 20%, of the original sulphur content, respectively. The SO₂ emissions from oil, coal, peat and natural gas were typically 1000, 600, 120, and < 10 mg MJ⁻¹, respectively.The emissions of oxides of nitrogen depended on the nitrogen content of the fuel and also on the combustion temperature. The NO_x emissions from plants burning oil, coal peat and natural gas were typically 100, 300, 160 and 100 mg MJ⁻¹, respectively. The lowest emissions were measured in the small natural gas-fired district heating plants (20–30 mg NO_x MJ⁻¹).The emissions of fly ash and various elements depended mainly on the ash content of the fuel and on the efficiency of the dust collectors, which decreases sharply when the power plant output exceeds its nominal value. When the dust separation efficiency is 99% for coal- and peat-fueled power plants, and when there are no dust collectors in oil-fueled power plants, the typical fly ash emissions are 45, 20 and 25 mg MJ⁻¹, respectively. Characteristic emissions of heavy metals and natural radioactive elements were greatest in the combustion of coal, with the exception of vanadium and nickel, of which the greatest emissions were from oil; the greatest emissions of ²¹⁰Po were from peat.The PAH emissions of the different fuel-fired power plants were, with one exception, similar (2–10 μg MJ⁻¹). Emissions from the circulating fluidized bed combustion of peat were about 10 times (40 μg MJ⁻¹) those of the other methods of combustion.     

Statistical estimate of mercury removal efficiencies for air pollution control devices of municipal solid waste incinerators

Although representative removal efficiencies of gaseous mercury for air pollution control devices (APCDs) are important to prepare more reliable atmospheric emission inventories of mercury, they have been still uncertain because they depend sensitively on many factors like the type of APCDs, gas temperature, and mercury speciation. In this study, representative removal efficiencies of gaseous mercury for several types of APCDs of municipal solid waste incineration (MSWI) were offered using a statistical method. 534 data of mercury removal efficiencies for APCDs used in MSWI were collected. APCDs were categorized as fixed-bed absorber (FA), wet scrubber (WS), electrostatic precipitator (ESP), and fabric filter (FF), and their hybrid systems. Data series of all APCD types had Gaussian log-normality. The average removal efficiency with a 95% confidence interval for each APCD was estimated. The FA, WS, and FF with carbon and/or dry sorbent injection systems had 75% to 82% average removal efficiencies. On the other hand, the ESP with/without dry sorbent injection had lower removal efficiencies of up to 22%. The type of dry sorbent injection in the FF system, dry or semi-dry, did not make more than 1% difference to the removal efficiency. The injection of activated carbon and carbon-containing fly ash in the FF system made less than 3% difference. Estimation errors of removal efficiency were especially high for the ESP. The national average of removal efficiency of APCDs in Japanese MSWI plants was estimated on the basis of incineration capacity. Owing to the replacement of old APCDs for dioxin control, the national average removal efficiency increased from 34.5% in 1991 to 92.5% in 2003. This resulted in an additional reduction of about 0.86 Mg emission in 2003. Further study using the methodology in this study to other important emission sources like coal-fired power plants will contribute to better emission inventories.     

燃煤电厂烟气脱硝系统液氨气化器控制方式

论述了燃煤电厂烟气脱硝对于环境保护的重要性和必要性,在燃煤电厂烟气脱硝系统的选择性催化还原法（SCR）中最常用的设备蒸汽水浴式液氨气化器的控制要点及控制方式。     

水泥行业烟气脱硝技术浅析

近年来,随着我国经济的快速发展和工业化水平的显著提高,大气污染状况日益严重,我国SO2的排放量已经位居世界第二位,NOx排放量也在持续增长。烟气脱硫、脱硝已成为我国的一项重要任务,水泥厂排放的NOx是目前最主要的NOx来源之一,如果不加以控制,我国未来的酸雨污染可能将由硫酸型向硫酸/硝酸复合型发展,氮氧化物排放的影响日益突现,烟气脱硝已势在必行。水泥厂烟气的脱硝技术主要有选择性催化还原法(SCR)和选择性非催化还原法(SNCR)。有效控制煤燃烧造成的大气污染。控制煤燃烧过程中的氮氧化物排放,需要选择合理的烟气脱硝技术。介绍了水泥厂氮化物的生成途径,综述了各种脱硝技术方法及相关技术问题,对于高效烟气脱硝装置的选择有着实际意义。     

CO2, CO, and Hg emissions from the Truman Shepherd and Ruth Mullins coal fires, eastern Kentucky, USA

Carbon dioxide (CO₂), carbon monoxide (CO), and mercury (Hg) emissions were quantified for two eastern Kentucky coal-seam fires, the Truman Shepherd fire in Floyd County and the Ruth Mullins fire in Perry County. This study is one of the first to estimate gas emissions from coal fires using field measurements at gas vents. The Truman Shepherd fire emissions are nearly 1400 t CO₂/yr and 16 kg Hg/yr resulting from a coal combustion rate of 450-550 t/yr. The sum of CO₂ emissions from seven vents at the Ruth Mullins fire is 726 ± 72 t/yr, suggesting that the fire is consuming about 250-280 t coal/yr. Total Ruth Mullins fire CO and Hg emissions are estimated at 21 ± 1.8 t/yr and > 840 ± 170 g/yr, respectively. The CO₂ emissions are environmentally significant, but low compared to coal-fired power plants; for example, 3.9 × 10⁶ t CO₂/yr for a 514-MW boiler in Kentucky. Using simple calculations, CO₂ and Hg emissions from coal-fires in the U.S. are estimated at 1.4 × 10⁷-2.9 × 10⁸ t/yr and 0.58-11.5 t/yr, respectively. This initial work indicates that coal fires may be an important source of CO₂, CO, Hg and other atmospheric constituents.     

Mercury in air and plant specimens in herbaria: a pilot study at the MAF Herbarium in Madrid (Spain)

We present data from a study of mercury concentrations in air and plant specimens from the MAF Herbarium in Madrid (Spain). Hg (gas) emissions from old plant collections treated with mercuric chloride (HgCl(2)) in herbaria may pose a health risk for staff working in installations of this type. This is an issue not yet properly addressed. Plants that underwent insecticide treatment with HgCl(2) at the MAF Herbarium until the mid 1970s have persistent high concentrations of Hg in the range 1093-11,967 microg g(-1), whereas untreated specimens are in the range of 1.2-4.3 microg g(-1). The first group induces high concentrations of Hg (gas) in the main herbarium room, with seasonal variations of 404-727 ng m(-3) (late winter) and 748-7797 ng m(-3) (early summer) (baseline for Hg: 8 ng m(-3)). A test survey at another herbarium in Madrid showed even higher concentrations of Hg (gas) above 40,000 ng m(-3). The World Health Organization guidelines for chronic exposure to Hg (gas) are estimated at a maximum of 1000 ng m(-3). While staff was aware of the existence of HgCl(2) treated plants (the plant specimen sheets are labelled as 'poisoned'), they had no knowledge of the presence of high Hg (gas) concentrations in the buildings, a situation that may be relatively common in herbaria.