Contribution Of Coal Combustion Research Articles

The impacts of firework burning at the Chinese Spring Festival on air quality: insights of tracers, source evolution and aging processes

Abstract. To understand the impact of firework-burning (FW) particles on air quality and human health during the winter haze period, 39 elements, 10 water-soluble ions and 8 fractions of carbonaceous species in atmospheric PM2.5 in Nanjing were investigated during the 2014 Chinese Spring Festival (SF). Serious regional haze pollution persisted throughout the entire sampling period, with PM2.5 averaging at 113 ± 69 μg m−3 and visibility at 4.8 ± 3.2 km. The holiday effect led to almost all the chemical species decreasing during the SF, except for Al, K, Ba and Sr which were related to FW. The source contributions of coal combustion, vehicle emission and road dust decreased dramatically, whereas FW contributed to about half of the PM2.5 during the SF period. The intensive emission of FW particles on New Year's Eve accounted for 60.1% of the PM2.5. Fireworks also obviously modified the chemical compositions of PM2.5, with 39.3% contributed by increased organic matter, followed by steadily increased loadings of secondary inorganic ions. The aging processes of the FW particles lasted for about 4 days reflected by the variations of Ba, Sr, NH4+, NO3−, SO42− and K+, characterized by heterogeneous reactions of SO2 and NOx on crustal materials directly from FW, the replacement of Cl− by NO3− and SO42−, coating of NO3− and SO42− on soot, formation of secondary organic aerosols and metal-catalyzed formation of NO3− and SO42− at higher relative humidity. During aging, the main contributors to the extinction coefficient shifted from elemental carbon and organic matter to ammonium sulfate. The particles raised higher cancer risk of 1.62 × 10−6 by heavy metals (especially for Cd and As). This study provided detailed composition data and first comprehensive analysis of the aging processes of FW particles during the serious haze pollution period and their potential impact on human health.

Carbonaceous aerosols recorded in a southeastern Tibetan glacier: analysis of temporal variations and model estimates of sources and radiative forcing

Abstract. High temporal resolution measurements of black carbon (BC) and organic carbon (OC) covering the time period of 1956–2006 in an ice core over the southeastern Tibetan Plateau show a distinct seasonal dependence of BC and OC with higher respective concentrations but a lower OC / BC ratio in the non-monsoon season than during the summer monsoon. We use a global aerosol-climate model, in which BC emitted from different source regions can be explicitly tracked, to quantify BC source–receptor relationships between four Asian source regions and the southeastern Tibetan Plateau as a receptor. The model results show that South Asia has the largest contribution to the present-day (1996–2005) mean BC deposition at the ice-core drilling site during the non-monsoon season (October to May) (81%) and all year round (74%), followed by East Asia (14% to the non-monsoon mean and 21% to the annual mean). The ice-core record also indicates stable and relatively low BC and OC deposition fluxes from the late 1950s to 1980, followed by an overall increase to recent years. This trend is consistent with the BC and OC emission inventories and the fuel consumption of South Asia (as the primary contributor to annual mean BC deposition). Moreover, the increasing trend of the OC / BC ratio since the early 1990s indicates a growing contribution of coal combustion and/or biomass burning to the emissions. The estimated radiative forcing induced by BC and OC impurities in snow has increased since 1980, suggesting an increasing potential influence of carbonaceous aerosols on the Tibetan glacier melting and the availability of water resources in the surrounding regions. Our study indicates that more attention to OC is merited because of its non-negligible light absorption and the recent rapid increases evident in the ice-core record.

Mode and Place of Origin of Carbonaceous Aerosols Transported From East Asia to Cape Hedo, Okinawa, Japan

This study investigated the source categories and emission areas of carbonaceous aerosols transported from East Asia to the East China Sea. Mass concentrations of heavy metals, ionic components, organic carbon, and elemental carbon (EC) were measured at the Cape Hedo Atmosphere and Aerosol Monitoring Station in Okinawa, Japan, throughout 2010. The relative influences of different categories of aerosols were determined by positive matrix factorization, and the source regions of each emissions category were evaluated by using the total potential source contribution function. Five source categories were identified: dust, sea salt and nitrate, secondary species, coal combustion, and oil combustion. The results showed that the major source of aerosols in North China is coal combustion, whereas the major source in South China, Japan, and Korea is oil combustion. The relative contributions of the five sources to EC concentrations at Cape Hedo were dust 7.0%, sea salt and nitrate 19.1%, secondary species 28.5%, oil combustion 12.8%, and coal combustion 32.6%. In particular, wintertime coal combustion in residential areas of North China contributed significantly to EC in 2010. The results also indicate that the contribution of coal combustion in source areas was higher in winter (52%), whereas the contribution of oil combustion was higher in spring (33%).

A 200-year record of polycyclic aromatic hydrocarbons contamination in an ombrotrophic peatland in Great Hinggan Mountain, northeast China

Peat bogs are regarded as one of the faithful archives of atmospheric polycyclic aromatic hydrocarbons (PAHs) deposition, and a large number of studies on PAHs accumulation in peatlands have been reported in Europe and North America. Comparatively little information is available on peat chronological records of atmospheric PAHs flux in China. We investigated the concentrations and historical accumulation rates of PAHs (AR PAHs) through geochemical analysis of three 210Pb-dated ombrotrophic peat cores from Great Hinggan Mountain, northeast China. Eight USEPA priority PAHs were detected and they are naphthalene (Nap), acenaphthylene (Acl), acenaphthene (Ace), fluorence (Flu), phenanthrene (Phe), anthracene (Ant), fluoranthene (Fla) and pyrene (Pyr), respectively. The average total eight PAHs (tPAHs) concentrations are 135.98 - 262.43 μg kg-1 and the average AR tPAHs over the last two centuries are 96.45 - 135.98 μg m-2 yr-1. The Ace, Acl and Phe account for 30.93 - 54.04%, 25.29 - 35.81%, and 9.14 - 19.84% of the tPAHs, respectively, and have significant positive correlations with the tPAH. As a result, they are regarded as the iconic compounds of PAHs pollution in this area. A ca. 200-yr atmospheric PAHs contamination history was reconstructed from the temporal sequences of both concentration and AR tPAHs, suggesting the variation of local environmental pollution. The main sources of the PAHs are identified by two isomer ratios as petrogenic origin including oil extraction and refining process as well as their combustions for industrial development. In addition, the contribution of coal combustion for industrial activities and resident heating could not be ignored. But prior to 1860, the undeveloped industry and most of agricultural activities might mainly account for the low level of PAHs, although it could infer a long-range input of atmospheric PAHs from other industrial areas. Therefore, there is a global implication to study long-term PAHs pollution records and all the results will provide practical significance in formulating policies to achieve sustainable and healthy development.

Latest Permian chars may derive from wildfires, not coal combustion

The Permian-Triassic boundary extinction event was the largest biological crisis of the Phanerozoic. One of the principle triggers for the mass extinction is thought to be greenhouse warming resulting from the release of CH 4 from basalt-coal interaction during the extensive Siberian Traps (Russia) eruptions. Observations of organic matter interpreted to be coal combustion products (fly ash) in latest Permian marine sediments have been used to support this hypothesis. However, this interpretation is dependent upon vesicular chars being fly ash (coal combustion derived) and not formed by alternative mechanisms. Here we present reflectance microscopy images of vesicular chars from Russian Permian coals, and chars from modern tundra, peatland, and boreal forest fires, to demonstrate that despite a difference in precursor fuels, wildfires are capable of generating vesicular chars that are morphologically comparable to end-Permian fly ash. These observations, coupled with extensive global evidence of wildfires during this time interval, call into question the contribution of coal combustion to the end-Permian extinction event.

Particulate carbon emissions from electrostatic precipitators used for mercury emissions control: operational factors and implications

Injection of powdered activated carbon (PAC) into the combustion flue gas of a coal-fired boiler is a leading approach to reducing anthropogenic mercury emissions. Small particle size and poor electrical properties are known to make carbonaceous particles more difficult to remove from a gas stream by electrostatic precipitation, by far the dominant particulate control technology for coal-fired boilers. The present analysis estimates PAC emissions from electrostatic precipitators (ESPs) and considers both the operational factors driving such emissions as well as their implications in terms of adsorbed mercury concentrations and their potential to act as a climate forcing agent similar to black carbon. The results of the analysis find the potential for PAC to increase particulate carbon emissions by tens of percent to over 150 % in the worst-case scenario considered. Such emissions could increase the contribution of coal combustion to total anthropogenic emissions of particulate carbon by several percentage points. Elevated levels of mercury on such emissions can translate into gas-phase-equivalent mercury concentrations approaching 1 ppb. The most important uncertainty influencing these results is the removal efficiency within ESPs of PM2.5-activated carbon particles.

Quantitative evaluation of emission controls on primary and secondary organic aerosol sources during Beijing 2008 Olympics

Abstract. To assess the primary and secondary sources of fine organic aerosols after the aggressive implementation of air pollution controls during the 2008 Beijing Olympic Games, 12 h PM2.5 values were measured at an urban site at Peking University (PKU) and an upwind rural site at Yufa during the CAREBEIJING-2008 (Campaigns of Air quality REsearch in BEIJING and surrounding region) summer field campaign. The average PM2.5 concentrations were 72.5 ± 43.6 μg m−3 and 64.3 ± 36.2 μg m−3 (average ± standard deviation, below as the same) at PKU and Yufa, respectively, showing the lowest concentrations in recent years. Combining the results from a CMB (chemical mass balance) model and secondary organic aerosol (SOA) tracer-yield model, five primary and four secondary fine organic aerosol sources were compared with the results from previous studies in Beijing. The relative contribution of mobile sources to PM2.5 concentrations was increased in 2008, with diesel engines contributing 16.2 ± 5.9% and 14.5 ± 4.1% and gasoline vehicles contributing 10.3 ± 8.7% and 7.9 ± 6.2% to organic carbon (OC) at PKU and Yufa, respectively. Due to the implementation of emission controls, the absolute OC concentrations from primary sources were reduced during the Olympics, and the contributions from secondary formation of OC represented a larger relative source of fine organic aerosols. Compared with the non-controlled period prior to the Olympics, primary vehicle contributions were reduced by 30% at the urban site and 24% at the rural site. The reductions in coal combustion contributions were 57% at PKU and 7% at Yufa. Our results demonstrate that the emission control measures implemented in 2008 significantly alleviated the primary organic particle pollution in and around Beijing. However, additional studies are needed to provide a more comprehensive assessment of the emission control effectiveness on SOA formation.

Evidence of coal combustion contribution to ambient VOCs during winter in Beijing

Volatile organic compounds (VOCs) play an important role in ozone and secondary organic aerosol (SOA) formation, but VOCs sources during winter are not fully understood. To investigate VOCs sources during winter, mixing ratios of C2–C12 VOCs were measured at an urban site in Beijing from December 29, 2011 to January 17, 2012. Correlation analysis of toluene to benzene and i-pentane to n-pentane suggest that coal combustion could also be an important source for VOCs besides vehicular emissions. Source apportionment results show that coal combustion and vehicular emissions contributed 28%–39% and 31%–45% to ambient VOCs during winter, respectively. Backward trajectory analyses demonstrated that contributions from the burning of coal were higher when air masses came from southern regions outside Beijing. Close attention should be paid to VOCs emissions from coal combustion in Beijing city and the vicinity to the South.

Characterization and source apportionment of polycyclic aromatic hydrocarbons (PAHs) in sediments in the Yellow River Estuary, China

Concentrations and sources of polycyclic aromatic hydrocarbons (PAHs) were investigated in surface sediments of the Yellow River Estuary (YRE). The isobath-parallel tidal and residual currents play important roles in the variation of PAH distribution, such that the contamination level of PAHs in fine-grained sediments is significantly higher than in the relatively coarse grain size sediments. Both diagnostic ratios and principal component analysis (PCA) with multivariate linear regression (MLR) were used to apportion sources of PAHs. The results revealed that pyrogenic sources are important sources of PAHs. Further analysis indicated that the contributions of coal combustion, traffic-related pollution and mixed sources (spills of oil products and vegetation combustion) were 35, 29 and 36 %, respectively, using PCA/MLR. Pyrogenic sources (coal combustion and traffic-related pollution) contribute 64 % of anthropogenic PAHs in sediments, which indicates that energy consumption could be a predominant factor in PAH pollution of YRE. Acenaphthylene and acenaphthene are the two main species of PAHs with more ecotoxicological concern in YRE.

Relationships between PAHs and PCBs, and quantitative source apportionment of PAHs toxicity in sediments from Fenhe reservoir and watershed

Sedimentary samples from 28 sites throughout the Fenhe reservoir and upstream watershed in China were measured, to study the relationships between PAHs and PCBs as well as perform quantitative source apportionment of toxicity. The distributions of ∑16PAHs and ∑123PCBs showed high correlation. The ∑7C-PAHs (total concentrations of seven carcinogenic PAHs) varied from 87.7 to 2005.0ngg−1dw, and the ∑6DL-PCBs (total concentrations of six dioxin-like PCB congeners) were n.d.–5.96ngg−1dw. Toxicity and biological risk were assessed using toxic equivalent quantity (TEQ) and sediment quality guideline quotient (SQGQ). The BaP played the dominant role for TEQPAH at most sites (37.17–89.40%), although the CHR showed the highest concentration level. PCB-81 contributed the highest TEQPCB. High correlations were observed between ∑16PAHs and ∑7C-PAHs, ∑123PCBs and ∑6DL-PCBs, ∑7C-PAHs and ∑6DL-PCBs as well as TEQPAH and TEQPCB. Furthermore, quantitative source apportionments for PAHs concentrations and TEQ were carried out, combining the positive matrix factorization (PMF) with the formula of TEQ. For most sites, the vehicular sources were the largest contributors to TEQPAH (46.58%), while coal combustion sources were the highest contributor for PAHs concentrations (43.31%). The relatively higher correlations between PCBs and contributions of coal combustion to PAHs might imply the similar distribution of industrial sources for PAHs and PCBs.

ANALYSIS OF CHARACTERISTICS AND SOURCES OF PM10-BOUND PAHs IN TIANJIN City

Background and Aims: Polycyclic aromatic hydrocarbons (PAHs) are a series of certain compounds, many of which have proven to be mutagenic and/or carcinogenic. This study elucidates the temporal and spatial distribution of PM10-bound PAHs in Tianjin, as well as their possible sources and healthy impacts, to provide a baseline reference on exposure assessment, health risk, and pollution controlling in such a densely populated city. Methods: Atmospheric PM10 samples were collected at 8 sampling sites in Tianjin City every six-day from September 2009 to August 2010. The mass concentrations of 16 PAHs loaded in PM10 samples were measured by GC-MS method. PAHs ratios, PCA and PMF methods were applied for source identification. Results: The results shows that the total mass concentrations of PM10-bound PAHs ranged from 10.91 ng m-3 to 1988.81 ng m-3, while the average concentration was 41.91 ng m-3 in spring, 24.56 ng m-3 in summer, 129.78 ng m-3 in autumn and 355.32 ng m-3 in winter. Vehicle exhaust was recognized to be a most significant PAHs contributor in both summer and winter, while and the contribution of coal combustion increased in winter. Conclusions: The total mass concentrations of PM10-bound PAHs varied temporally and spatially at a remarkable extent, with a higher concentration in winter and a lower one in summer, while concentration was the highest in industrial area. With more complex molecular structures, PAHs species with four and more rings composed most of the PAHs concentrations, namely, four-rings in winter and five and six-rings in summer. Coal combustion, vehicle exhaust and steel industry emission were identified to be three major sources of PM10-bound PAHs, however, in summer there may existed more other sources such as biomass combustion and refinery.

Air particulate matter pollution in Ulaanbaatar, Mongolia: determination of composition, source contributions and source locations

Ulaanbaatar, the capital city of Mongolia is subject to high air particulate matter pollution episodes during winter and during dust storm events in spring and autumn that have severe implications for the health of the exposed population. This paper presents the results of fine (PM2.5) and coarse (PM10–2.5) particulate matter monitoring in Ulaanbaatar from 2004 to 2008 and receptor modelling to determine the sources contributing to particulate matter pollution. Ion Beam Analysis was used to determine elemental concentrations in the two size fractions and black carbon was measured with a light reflectance device. Mass contributions to ambient particle concentrations from emission sources were estimated by positive matrix factorisation and air mass back–trajectory analysis was used to assess probable source locations. The results show that crustal matter sources are the primary contributors to the coarse particle fraction. Combustion sources (coal combustion, biomass burning, and motor vehicles) dominate the fine fraction of particulate matter in the Ulaanbaatar airshed, primarily from local emission sources but forest fires to the north can be a significant contributor to biomass burning concentrations at times. Analysis of seasonal differences showed that coal combustion processes were largely responsible for fine particle air pollution episodes during winter. Temporal trends show an increase in the coal combustion contributions over the monitoring period. We suggest that this is linked to the increase in the Ulaanbaatar population and a consequent increase in the use of coal for power generation and domestic heating purposes.

Polycyclic aromatic hydrocarbons in surface sediments of Laizhou Bay, Bohai Sea, China

Concentration, distribution, and sources of 16 polycyclic aromatic hydrocarbons (PAHs) were investigated in surface sediments of Laizhou Bay, China. Total PAH concentrations ranged from 97.2 to 204.8 ng/g, with a mean of 148.4 ng/g. High concentrations of PAHs were found in the fine-grained sediments on both sides of the Yellow River estuary (YRE). In contrast, low levels of PAHs were observed in relatively coarse grain sediments, suggesting hydrodynamics influence the accumulation of sedimentary PAHs. The YRE and its adjacent area is the main sink for Yellow River-derived PAHs. Both PAH isomer ratios and principal component analysis (PCA) with multivariate linear regression (MLR) were applied to apportion sources of PAHs. Results indicated that both pyrogenic and petrogenic PAH sources were important. Further PCA/MLR analysis showed that the contributions of coal combustion, petroleum combustion and a combined source of spilled oil and biomass burning were 41, 15 and 44%, respectively. From an ecotoxicological viewpoint, the studied area appears to have low levels of PAH pollution.

The sources and seasonal variations of organic compounds in PM2.5 in Beijing and Shanghai

Fine aerosol samples were collected throughout spring, summer, and winter in 2004∼2005 at a major urban traffic junction (BNU) and a suburban location (MY) in Beijing and at a downtown site (SH) in Shanghai, China. Ten of the 16 EPA priority polycyclic aromatic hydrocarbons (PAHs), seven fatty acids, levoglucosan, and cholesterol were identified and quantified. PAHs detected in Beijing and Shanghai were up to one order of magnitude higher than those reported in the developed countries either in urban or suburban areas, while levoglucosan was one order of magnitude lower than that in other countries for no biomass combustion in domestic heating in the mega-cities in China. PAHs showed the same seasonal trend in all sampling sites as the highest in winter and the lowest in summer, while fatty acids no pronounced seasonal variation. A significant fraction of levoglucosan from cooking with higher concentrations in urban than in suburban area contributed to the ambient atmosphere, indicating that the main source of levoglucosan in urban environment would be cooking rather than biomass burning. The relative contributions of coal combustion and vehicle exhaust sources to PAHs in fine aerosols were preliminarily estimated to be 1:2 in Beijing and 1:1 in Shanghai, revealing that the air pollution in these mega-cities in China was mainly the mixing of coal combustion with vehicle exhaust. Cooking was one of the major sources of organic aerosols in both Beijing and Shanghai.

Source apportionment of polycyclic aromatic hydrocarbons (PAHs) in surface sediments of the Huangpu River, Shanghai, China

We applied cluster analysis and principal component analysis (PCA) with multivariate linear regression (MLR) to apportion sources of polycyclic aromatic hydrocarbons (PAHs) in surface sediments of the Huangpu River in Shanghai, China, based on the measured PAH concentrations of 32 samples collected at eight sites in four seasons in 2006. The results indicate that petrogenic and pyrogenic sources are the important sources of PAHs. Further analysis shows that the contributions of coal combustion, traffic-related pollution and spills of oil products (petrogenic) are 40%, 36% and 24% using PCA/MLR, respectively. Pyrogenic sources (coal combustion and traffic related pollution) contribute 76% of anthropogenic PAHs to sediments, which indicates that energy consumption is a predominant factor of PAH pollution in Shanghai. Rainfall, the monsoon and temperature play important roles in the distinct seasonal variation of PAH pollution, such that the contamination level of PAHs in spring is significantly higher than in the other seasons. Brief We apportion PAHs in surface sediments of the Huangpu River and show that coal combustion, traffic-related pollution, and petroleum spillage are the major sources.

A life cycle inventory of coal used for electricity production in Florida

Coal-fired power plants are anticipated to be increasingly used as a source of energy in the United States, particularly in states such as Florida that are experiencing rapid population growth and energy demands. While the emissions from coal combustion are a focus of intense study, little attention has been given to the emissions' contributions from other stages involved in the life cycle of coal used for electricity generation. This study inventories material and energy inputs and emissions in not only the Materials Processing stage (coal combustion) but also in the Raw Material Extraction (including coal mining and preparation) and Material Disposal (involving coal combustion products) stages, using data collected from four coal-burning utilities in Florida and SimaPro software (version 5.1, PRé Consultants, The Netherlands). Total emissions to air from all three stages are significantly higher than to water or land, with 78% of the air emissions attributed to carbon dioxide from coal combustion. Coal mining and preparation contributes the largest quantities of non-methane volatile organic compounds and methane (over 98%) as well as the most total dissolved solids to water (over 76%). Disposal of coal combustion products, typically by either landfilling or surface impoundment, results in the largest emissions of particulate matter (PM 10) to air (41%), a significant emission of total dissolved solids to water (over 22%), and a variety of metals to land. These results verify the major contributions of coal combustion to air emissions and show that the emissions from the Raw Material Extraction and Material Disposal stages may result in a significant enough negative environmental impact to warrant pursuit of pollution control and prevention opportunities in these stages as well.

Ambient Aerosol Concentrations of Elements Resolved by Size and by Source: Contributions of Some Cytokine-Active Metals from Coal- and Oil-Fired Power Plants

Size-segregated aerosol samples were collected with Micro-Orifice Impactors in Baltimore, MD, a typical northeastern port city where air quality is influenced by urban and industrial sources. The size fractions were analyzed for up to 32 elements by Instrumental Neutron Activation Analysis and the results were used in a chemical mass balance model to resolve the contributions to ambient levels by size and by source. Resolution by size improves interpretation of the results as primary accumulation aerosol populations from different sources are frequently resolved in the size spectra of their marker species. With a 15-source model, agreement between measured and predicted concentrations was within 40% for all elements except Co, Cr, Cs, Ti, and W. The results suggest that coal-fired power plants are minor sources of the respirable fractions of several metals, including Cr (19%), V (5%), and Zn (<1%), which are known to be active in cytokine assays, a metric of inflammatory response that is linked to reactive oxygen species production and lung cell necrosis in in vitro and animal studies. Coal combustion contributions to ambient levels of As, Fe, Co, Mn, and Sb were 16, 13, 11, 2.7, and 4.8%, respectively. In addition, coal contributions are likely 30% less than these after correction of the source signature for vapor-phase Se emissions. Major fractions of respirable airborne V and Co (each about 55%), and Zn (70%) were attributed to aerosol emitted from fuel oil combustion and incinerators, respectively. Steel production was the major source for airborne Cr (45%), Fe (52%), and Mn 52%); whereas large (70 and 57%) fractions of airborne As and Sb were attributed to an unidentified source which was resolved in the size spectra. Metal concentrations attributed to long-range transport, owing to their association with secondary sulfate were typically negligible, except for Mn (15%), Se (28%), and Zn (5%).

Coal Gasification in a Transport Reactor

An advanced transport reactor gasifier was operated using three different coals: Illinois #6 bituminous, Wyodak Powder River Basin subbituminous, and a Sufco Utah bituminous coals. A steady-state model was developed to evaluate the relative contributions of coal combustion and gasification of coal/char in this high-throughput reactor. The tests employed in-bed calcium-based sorbent for sulfur capture. The model was based on elemental mass and energy balances and assumed instantaneous devolatilization and combustion and kinetically limited gasification reactions in a continuously stirred tank reactor. The experimental results on the reaction of these three coals were compared with model predictions. The simulated results compared favorably with the experimental results (e.g., gas composition, carbon conversion, and reactor temperature). The bituminous coal data were accurately simulated as substoichiometric combustion processes. The more reactive subbituminous coal exhibited significant gasification conve...

Regional characteristics of sulfur and lead isotope ratios in the atmosphere at several Chinese urban sites.

Sulfur and lead isotope ratios in the atmosphere were measured at several selected sites (Harbin, Changchun, Dalian, Waliguan, Shanghai, Nanjing, Guiyang) in China and Tsukuba (Japan), to reveal regional sources characteristics over Eastern Asia. Average S isotope ratios for SO2 and sulfate in the atmosphere in China were close to those of the coals used in each region, indicating a considerable contribution of coal combustion to the sulfur compounds in the atmosphere. Most northern cities had around 5% sulfur isotope ratio, while Guiyang, a southwestern city in China, showed a considerably lower sulfur isotope ratio (about -3%) because of the unusually light sulfur isotope ratio of coals in this region. These were considerably different from the value (-1.4%) for Tsukuba (Japan). Lead isotope ratios also suggested that coal combustion considerably contributed to atmospheric lead in some cases in China. At the same time, influences by the emission of Chinese lead ores were also observed in northern cities. Seasonal variations of both sulfur and lead isotope ratios indicated the existence of a certain amount of industrial sources other than coal combustion. In addition, fractionation effect between SO2 and sulfate showed a seasonal tendency (high in winter (0-6%) and low in summer (-1-3%)), suggesting the oxidation pathway of SO2 changed seasonally.

Lead contents of coal, coal ash and fly ash

Flameless atomic absorption spectrometry is applied for the determination of Pb in coal, coal ash and fly ash. Lead concentrations in coal and coal ash ranging from respectively 7 to 110 µg g−1 and 120 to 450 µg g−1 are found. A mean concentration of 1520 µg g−1 in fly ash corresponding to a concentration of 117 µg m−3 in the effluent gas suggests the importance of coal combustion as an atmospheric source of Ph. The contribution of coal combustion to the total Pb emissions is conservatively estimated at 6%.