Biomarker compounds in ash from coal combustion in domestic furnaces (Upper Silesia Coal Basin, Poland)

Fuel 102 (2012) 333–344

Contents lists available at SciVerse ScienceDirect

Fuel journal homepage: www.elsevier.com/locate/fuel

Biomarker compounds in ash from coal combustion in domestic furnaces (Upper Silesia Coal Basin, Poland) Monika J. Fabian´ska ⇑, Danuta Smółka-Danielowska ´ ska Street 60, 41-200 Sosnowiec, Poland University of Silesia, Faculty of Earth Sciences, Be˛dzin

h i g h l i g h t s " We investigate organic compounds in coal ash from domestic furnaces. " Two types of organic compounds in ash extracts: from source coal and heat-originated. " Biomarkers show recognizable distributions of source bituminous coal. " Some biomarkers distributions are partially affected by heat. " Temperature and oxygen level influence biomarker distributions.

a r t i c l e

i n f o

Article history: Received 6 April 2011 Received in revised form 5 July 2012 Accepted 5 July 2012 Available online 20 July 2012 Keywords: Coal combustion Coal ash Coal waste Gas chromatography–mass spectrometry Biomarkers

a b s t r a c t Organic compounds occurring in coal ash of known mineralogy were investigated. Ash came from two domestic furnaces using bituminous coal from the Upper Silesia Coal Basin. Dichloromethane extracts of ash were analyzed with gas chromatography–mass spectrometry (GC–MS) for biomarkers from fuel and formed during combustion. Distributions of aliphatic hydrocarbons, aromatic and polar compounds were researched. Results were compared with those found for power plant coal ash, coal wastes which underwent self-heating and source bituminous coal. It was found that geochemical features of plant coal ash organic matter reflects mainly geochemistry of source bituminous coal. Several groups of biomarkers such as as n-alkanes, steranes and pentacyclic triterpanes show distributions recognizable as coal-deriving what enables to identify source fuel. Values of most biomarker and aromatic hydrocarbon parameters show minor changes due to heat of the combustion process. The most advanced changes are found in distributions of alkylnaphthalenes, pristane, phytane and lighter n-alkanes reflected by values of Pr/Ph, Pr/nC17 and Ph/n-C18 ratios. Much less extensive changes are seen in distributions of pentacyclic triterpanes which make them the most useful biomarker group for source fuel characterisation. Most of biomarkers are probably present in coal ash in unburnt coal particles occurring in ash due to low temperature in domestic furnaces favoring organic matter preservation. Ó 2012 Elsevier Ltd. All rights reserved.

1. Introduction Due to it its abundant world’s reserves coal is still the primary energy/heat source in the world [1]. Coal combustion generates a great amount of ash showing adsorbing properties. It has been estimated that the worldwide production of coal ash from only coalfired power plants exceeds 550  106 tones/year [2]. While in power plants the large part of coal mineral fraction is collected in cyclones (fly ash) to be stored in waste dumps or reused in building industry, in combustion for domestic purposes finer fractions of ash are emitted to the atmosphere or dumped out without any control. Due to its adsorbing properties coal ash can contain ⇑ Corresponding author. Tel.: +48 32 368 94 32; fax: +48 32 291 58 65. E-mail address: [email protected] (M.J. Fabian´ska). 0016-2361/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.fuel.2012.07.012

organic compounds deriving from parent coal or formed in burning process, e.g. [3]. While relatively low amounts of carbon in fly ash from coal-fired power plants has been found [4,5], ash from domestic combustion contain higher amounts of it due to generally lower temperatures of combustion and more limited access of air to fuel [6–8]. To evaluate the possible impacts of coal ash organic matter on human health and the environment it is important to characterize its chemical composition. Many attempts have been made to link the various type of carbon in fly ash with parent coal properties, such as rank and maceral composition [9,10]. Liptinite is completely burnt during combustion without leaving any char particles whereas vitrinite and inertinite form isotropic and anisotropic carbon [5]. Vitrinite char is a reactive component of coal, forming large angular particles, mostly volatilized during

334

´ ska, D. Smółka-Danielowska / Fuel 102 (2012) 333–344 M.J. Fabian

combustion. Inertinite macerals, being natural chars, burn lessreadily than the vitrinite particles and form isotropic particles. Low rank coals tend to produce isotropic char whereas higher rank bituminous coals anisotropic coke with various granular optical textures [9–14]. The varying temperature and oxygen contents in the combustion zone determine a degree of organic matter alteration and type of compounds emitted from fuel combusted. Low temperature of burning is common in domestic furnaces. As a result smoldering (<300 °C) prevails in them. This causes a release of organic compounds by volatilization/steam stripping effect from coal combusted [15]. The extent of the process is affected by coal moisture content related to coal rank. Apart from volatilization the primary chemical reactions under smoldering condition include water elimination, depolymerization and fragmentation of coal macromolecule, organic matter oxidation, and char formation. Numerous organic compounds have been identified in smoke emissions from various fuels (biomass and fossil fuels), e.g. [4,15–18]. These compounds are related to organic components of the parent coal. Among them are biomarkers belonging to various groups of organic compounds, previously identified in the world’s coals of different age, rank and maceral composition. These compounds such as n-alkanes, acyclic isoprenoids, sesquiterpenoids, diterpenoids, steranes, tri- and pentacyclic triterpanes can be applied as markers of a particular source of organic matter helping in its identification and assessment of its input to the environment, for example, [19–24].

2. Bituminous coals of the Upper Silesia Coal Basin (Poland) The majority of Polish resources of bituminous (hard) coals are located in Upper Carboniferous (Pennsylvanian) strata (Fig. 1). In this study, bituminous coal of the Upper Silesia Coal Basin (USCB),

the most often fuel applied for both domestic and industrial purposes, is used as the source of coal ash investigated. Domestic and power plant coal ash contained unburnt remains of organic compounds. Their composition is compared here to that of the source USCB bituminous coal and to coal and smelting wastes as well. The Upper Silesia Coal Basin is situated in the south-western part of Poland (Fig. 1). It was formed as a Variscan foredeep of the Moravo–Silesian fold zone [22,25]. The Upper Carboniferous coal-bearing succession, more than 8000 m thick, is a major part of the molasse infill. The lower paralic part of the sequence (Namurian A) consists of marine, shore, deltaic and fluvial deposits, whereas the upper part (Namurian B to Westphalian D) contains variable non-marine deposits [26].The ranks of coals in the USCB are variable. They range from subbituminous to high volatile bituminous coals. Maceral composition is more uniform; humic coals rich in vitrinites dominate here with rare sapropelic coals. The ranks of coals and maceral group composition of the USCB coals from the Polish basins were investigated in numerous research, for instance [27–30], among many others. Generally, vitrinite reflectance values tend to decrease eastward the basin. In the western USCB part they are in the range from 0.45 to 2.00, in the central part of the basin Ro = 0.80–1, 1%, whereas coals in the easternmost part (the Upper Vistula Coal Basin) are of the lowest rank (Ro  0.50%). In the last decade organic geochemistry of these bituminous coals was investigated [22,30–32]. Typical distributions of biomarkers such as n-alkanes, steranes, cyclic and acyclic isoprenoids were presented there. These research has shown that the organic matter contained in the coals and carbonaceous shales present in the same sequence was derived predominantly from higher plant (terrestrial) precursors, however depositional conditions and sources of organic matter changed sharply between deposition of the coals and the shales.

Fig. 1. Simplified geological map of the Upper Silesia Coal Basin (after [25,26]); MR-Michałkowice-Rybnik Overthrust, OB-Orłowa-Boguszowice Overthrust.

´ ska, D. Smółka-Danielowska / Fuel 102 (2012) 333–344 M.J. Fabian

3. The aim of the research Despite the high environmental importance of coal combustion by-products such as ash or slag there are only a few papers concerning residual organic compounds occurring in them. Mostly, these extensive investigations concerned fly ash or smoke as the most hazardous substances emitted to the air in combustion [4,15–18]. Far few attempts have been made to characterize unburnt organic matter present in ash [33,34] and none, to the authors knowledge, to find biomarkers present in it. The research presented in this paper aims to fill this gap in our knowledge concerning coal combustion. Since coal ash produced in power industry is applied to many aims such as building industry, or landfilling it is essential to recognize its geochemical features too, apart from the technological ones. It is also worth to mention here that coal ash from individual domestic furnaces is often treated as waste and dumped without any control. Up to now there is not any estimation of health hazards caused by such a practice. Moreover, it is known that coal ash can contain unburnt or only partially burnt particles of organic material [33,34]. Such particles were found also in ash from domestic furnaces utilizing USCB coals [35]. The aim of this research was:  to establish what organic compounds (if any) are present in coal ash from domestic furnaces, compared to those present in industrial ash, coal wastes which underwent self-heating and smelting wastes (slag);  to assess the relationship of the compounds present with the source material using biomarkers;  to assess changes in biomarker distribution caused by combustion (ash and slag) or self-heating (coal wastes). Since domestic coal combustion is considered to be most hazardous to the environment it is important to find what biomarker distributions are common for this emission source and to compare

335

it with that of ash from industrial power plants. In future, these results may enable to distinguish the domestic combustion input to organic pollution and to general background of organic compounds present in the urban air of large conurbations such as Upper Silesia. 4. Methodology 4.1. Samples collection and preparation Coal ash samples come from two domestic furnaces using Upper Silesia Basin coals (Poland) as a fuel for central heating purposes, one located in the Orzesze town (11 samples; sample codes A1–A11 in Table 1) and the second one located in the Piekary S´la˛skie town (8 samples; sample codes A12-A19 in Table 1). Ash was sampled in winter 2007/2008 (November, December and January). Industrial fly ash was taken as the averaged sample of three electrofilters in the Łagisza, Tychy and Halemba power plants (samples A20-A22 in Table 1). Coal wastes (sample codes W1-4) were sampled in three selected coal wastes dumps which underwent a self-heating episode in their history: the Rydułtowy–Anna dump storing coal wastes from the Rydułtowy Mine, the Janina from the Sobieski power plant, and the Maczki–Bór waste dump from various mines of the Upper Silesia Coal Basin. Samples comprise gangue mining material and are classified as mudstones and claystones with numerous coal laminae. Slag (samples SW1 and SW2) was sampled in the smelting waste dump storing wastes from the former ‘‘Silesia’’ Metallurgy Plant located in the northern area of the Katowice city (western Poland). The dump contains slag of variable grain size, and ash from coal liquefaction process. Vegetation, which partially covers the dump area comprises plant species resistant to the elevated heavy metals contents in soil. Samples were taken from the part of the dump without any plant or soil cover. To find correlation between biomarker distributions and source fuel, coals of known origin and properties were applied as the only fuel. Flotation concentrate of bituminous coal (C1 sample) comes

Table 1 Samples descriptions and extract yields (wt.%). Sample code

Sample type

Source

Extract yield (wt.%)

A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 A13 A14 A15 A16 A17 A18 A19 A20 A21 A22 W1 W2 W3 W4 SW1 SW2 C1

Coal Coal Coal Coal Coal Coal Coal Coal Coal Coal Coal Coal Coal Coal Coal Coal Coal Coal Coal Coal Coal Coal Coal Coal Coal Coal Slag Slag Coal

Domestic oven, Orzesze town Domestic oven, Orzesze town Domestic oven, Orzesze town Domestic oven, Orzesze town Domestic oven, Orzesze town Domestic oven, Orzesze town Domestic oven, Orzesze town Domestic oven, Orzesze town Domestic oven, Orzesze town Domestic oven, Orzesze town Domestic oven, Orzesze town Domestic oven, Piekary S´la˛skie town Domestic oven, Piekary S´la˛skie town Domestic oven, Piekary S´la˛skie town Domestic oven, Piekary S´la˛skie town Domestic oven, Piekary S´la˛skie town Domestic oven, Piekary S´la˛skie town Domestic oven, Piekary S´la˛skie town Domestic oven, Piekary S´la˛skie town Tychy power plant Łagisza power plant Halemba power plant Rydułtowy–Anna coal waste dump Rydułtowy–Anna coal waste dump Janina coal waste dump Maczki–Bór coal waste dump Wełnowiec waste dump Wełnowiec waste dump Knurów coal mine

0.002 0.007 0.003 0.004 0.006 0.003 0.005 0.002 0.005 0.032 0.248 0.002 0.004 0.003 0.007 0.004 0.003 0.004 0.003 0.010 0.009 0.010 0.036 0.022 0.122 0.030 0.001 0.008 0.201

ash ash ash ash ash ash ash ash ash ash ash ash ash ash ash ash ash ash ash ash ash ash wastes wastes wastes wastes

336

´ ska, D. Smółka-Danielowska / Fuel 102 (2012) 333–344 M.J. Fabian

lected, evaporated and weighted. Extract yields are shown in Table 1. 4.3. Gas chromatography–mass spectrometry (GC–MS) An Agilent gas chromatograph 6890 with a HP–5 column (60 m  0.25 mm i.d.), coated by a 0.25 lm stationary phase film coupled with an Agilent Technology mass spectrometer 5973 was used. The experimental conditions were as follows: carrier gas – He; temperature – 50 °C (isothermal for 2 min); heating rate—up to 175 °C at 10 °C/min, to 225 °C at 6 °C/min and, finally, to 300 °C at 4 °C/min. The final temperature (300 °C) was held for 20 min. The mass spectrometer was operated in the electron impact ionization mode at 70 eV and scanned from 50–650 Da. Data were acquired in a full scan mode and processed with the Hewlett Packard Chemstation software. The compounds were identified by using their mass spectra, comparison of peak retention times with those of standard compounds, interpretation of MS fragmentation patterns and literature data [36,37]. Geochemical parameters were calculated using peak areas acquired in the manual integration mode. 4.4. X-ray powder diffraction The mineral composition of the samples was analyzed with X-ray diffractometer (XRD) method applying a Philips PW 3710 diffractometer, utilizing Co ka radiation with a graphite monochromator. The lamp electric voltage was 45 kV with current intensity of 30 mA. Impulse time counting in the method was 3 s and the rate of a tape movement was 0.02°/min. The estimated concentrations (%) of the analyzed amorphous phase are given using the X’PERT computer program. 5. Results 5.1. Mineral composition of ash

Fig. 2. Distribution of n-alkanes in the sample extracts (m/z = 71), (a) ash from the Orzesze domestic furnace (A10), (b) ash from the Piekary S´la˛skie domestic furnace (A13) and (c) coal waste (W3), (d) coal (C1); Pr = pristane, Ph = phytane.

from the Knurów Coal Mine (Upper Silesia Coal Basin, Poland). Its average ash content is about 25% whereas calorific value is 17000 kJ/kg. It was analyzed to compare its extract chemical composition and biomarker distributions to those found in coal ash extracts. The Orzesze domestic furnace used it as the only fuel whereas the Ruda S´la˛ska furnace applied bituminous coal from the Piekary S´la˛skie Mine, with average ash content 4.2% (wt.) and calorific value is 26420 kJ/kg. Samples descriptions and codes are shown in Table 1. Geochemical analyses comprised ultrasonic solvent extraction of powdered samples and the analysis of the total extracts by gas chromatography–mass spectrometry (GC–MS). The extracts were not separated into compound groups due to the very low extractability of most of the samples. 4.2. Solvent extraction All samples (ca 40 g) were dried at room temperature, powdered to grain size < 0.2 mm in an agalite mortar and extracted in a ultrasonic bath with a mixture of dichloromethane (DMC):ethanol = 4:1 (vol.:vol.) (20 min, 3–4 times). All extracts were col-

X-ray diffractive analyses show that the amorphous phase makes up about 65% (vol.) of the coal ash from both individual domestic furnaces. The following minerals (listed in the order of decreasing contents) occur among the identified mineral phases in the examined coal ash: quartz, feldspars (albite-anorthite), illlite, kaolinite, hemimorphite, mullite, calcite, dolomite, gypsum, pyrite, sphalerite, galena, magnetite, and hematite. The contents of amorphic phase in fly ash from the power plants is estimated to be in the range 50–65% (vol.). As previously, quartz shows the highest contents, with hematite, magnetite, anhydrite, gypsum, mullite, lime, and titanium oxides (listed in order of decreasing concentrations). The mineralogical composition of slag comprised quartz, illite, feldspars, muscovite, kaolinite, chlorite, mullite, calcite, dolomite, cerussite, anglesite, anhydrite, gypsum, pyrite, marcasite, pyrrhotite, sphalerite, galena, magnetite, hematite, and goethite. The mineralogical composition of waste dump included quartz, feldspars, mullite, illite, dolomite, kaolinite, siderite, pyrite, marcasite, magnetite, hematite, gypsum, and halite. 5.2. Extract yields Extract yields are variable, depending on sample type (Table 1), with C1 coal sample and W1–W4 coal wastes showing the highest and slag samples the lowest extractability (on average 0.082 and 0.005, respectively). Coal ash extract yields were mainly in the range from 0.002 to 0.032% (wt.), on average, with only one ash sample from the Orzesze domestic furnace having extract yield of 0.248% (wt.).

´ ska, D. Smółka-Danielowska / Fuel 102 (2012) 333–344 M.J. Fabian

337

Table 2 Aliphatic and aromatic biomarker parameters showing thermal influence on organic matter present in coal ash and coal wastes. Sample code

CPIa

R2/ R1b

Pr/ Phc

Pr/nC17 d

Ph/nC18e

C31abS/ (S + R)f

Ts/ (Ts + Tm)g

C30ba/ (ab + ba)h

C29aaaS/ (S + R)i

C29aaa/ (C29aaa + C29abb)j

MNRk

DNRl

MPI3m

(3-MB + 4MB)/DBFn

A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 A13 A14 A15 A16 A17 A18 A19 A20 A21 A22 W1 W2 W3 W4 SW1 SW2 C1

1.09 1.09 0.85 1.10 1.09 0.84 1.11 1.13 1.08 1.07 1.20 0.86 0.93 1.00 1.02 1.18 0.81 1.05 1.00 1.54 – 1.33 1.10 1.17 3.24 1.70 – 3.22 1.09

1.51 1.55 1.95 2.02 3.24 2.26 1.17 1.10 1.76 1.56 1.40 3.34 9.05 1.87 1.78 2.45 3.30 3.10 2.07 0.52 – 0.63 0.99 10.98 2.85 0.60 – 0.74 0.25

1.05 2.37 1.08 0.64 0.94 1.50 2.57 1.68 1.18 3.41 1.95 – – 0.42 1.03 – 0.51 – 1.94 0.60 – 1.35 3.54 – 2.35 1.71 – 1.45 2.48

0.83 0.98 1.05 1.81 0.70 1.27 1.36 1.59 1.15 1.30 0.88 – – 0.69 1.01 – 0.64 – 2.25 0.77 – 1.14 1.90 – 1.24 1.27 – 1.48 0.92

0.51 0.30 0.73 2.67 0.53 0.77 0.39 0.55 0.74 0.27 0.41 – – 2.23 0.76 – 0.70 – 1.43 1.35 – 0.70 0.48 – 0.47 0.68 – 0.92 0.34

0,51 0.59 0.52 0.53 0.56 – 0.58 0.53 0.49 0.57 0.64 – – – 0.51 – 0.48 0.55 0.44 – 0.56 0.58 0.59 – – 0.26 0.56 0.54 0.61

– 0.84 – 0.81 0.82 – 0.82 0.72 0.82 0.88 0.83 – – – 0.64 – 0.57 0.70 0.65 – 0.81 0.85 0.81 – – 0.45 0.77 0.85 0.89

– 0.26 – 0.29 0.24 – 0.24 0.28 0.26 0.26 0.25 – – – 0.55 – 0.40 0.41 0.49 – 0.11 0.16 0.29 – – – 0.01 0.16 0.19

– 0.48 – – 0.52 – – – – 0.44 – – – – – – – – – – 0.46 0.47 0.40 – 0.28 – 0.53 0.39 0.41

– 0.33 – – 0.40 – – – – 0.37 – – – – – – – – – – 0.47 0.47 0.23 – 0.40 – 0.54 0.47 0.37

– 1.09 – – – – 0.59 – – 0.55 1.04 – – – 0.69 – – – 0.27 – – 0.63 1.33 – 1.14 1.01 – 0.64 1.27

– 2.75 – 2.55

– 1.04 0.90 1.16 0.94 – 0.87 0.88 0.89 0.94 0.91 – – – – – – 0.85 – – – 0.66 0.91 1.26 – 0.48 – 1.08 0.90

– 0.33 – 0.17 0.17 – 0.69 – 0.68 0.24 0.59 – – – – – – – – – – 0.53 0.31 – 0.39 0.66 – 0.33 0.39

0.97 – – 1.04 2.49 – – – 1.43 – – – – – – 1.29 2.39 – – – – 1.60 1.69

– compounds absent or compounds present but contents too low to calculate a parameter value. a CPI = 0,5{[(n-C25 + n-C27 + n-C29 + n-C31 + n-C33)/(n-C24 + n-C26 + n-C28 + n-C30 + n-C32)] + [(n-C25 + n-C27 + n-C29 + n-C31 + n-C33)/(n-C26 + n-C28 + n-C30 + n-C32 + n-C34)]; Carbon Preference Index; m/z = 71; thermal maturity parameter [40]. b R2/R1 = [R(from n-C23 to n-C35) ]/[ R (from n-C13 to n-C22)]; m/z = 71, source indicator [52]. c Pr/Ph = pristane/phytane; parameter of environment oxicity (with exception of coals); m/z = 71 [41]. d Pr/n-C17 = pristane/n-heptadecane; m/z = 71 [43]. e Ph/n-C18 = phytane/n-octadecane; m/z = 71 [43]. f C31abS/(S + R) = 17a(H),21b(H)-29-homohopane 22S/(17a(H),21b(H)-29-homohopane 22S + 17a(H),21b(H)-29-homohopane 22R); m/z = 191; thermal maturity parameter [57]. g Ts/(Ts + Tm) = 18a(H)-22,29,30-trisnorneohopane/(18a(H)-22,29,30-trisnorneohopane + 17a(H)-22,29,30-trisnorhopane); m/z = 191; thermal maturity parameter [57]. h C30baabba) = 17b(H),21a(H)-29-hopane/(17a(H),21b(H)-29-hopane + 17b(H),21a(H)-29-hopane); m/z = 191; thermal maturity parameter [57]. i C29aaaS/(S + R) = a ratio of C29-5a,14a,17a(H)-stigmastane 20S to a sum of its diastereomers 20S and 20R ([57]. j C29aaa/(C29aaa + C29abb) = a ratio of C29-5a,14a,17a(H)-stigmastane (20S + 20R) to a sum of its diastereomers C29-5a,14a,17a(H)-stigmastane (20S + 20R) + C295a,14b,17b(H)-stigmastane (20S + 20R) [57]. k MNR = 2-methylnaphthalene/1-methylnaphthalene; m/z = 142; thermal maturity parameter [58]. l DNR-2 = (2,6-DMN + 2,7-DMN)/(1,4-DMN + 2,3-DMN + 1,5-DMN); DMN = dimethylnaphthalene; m/z = 156 [58]. m MPI-3 = (2-methylphenanthrene + 3-methylphenanthrene)/(1-methylphenanthrene + 9-methylphenanthrene); m/z = 192; thermal maturity parameter [61]. n (3-MB + 4-MB)/DBF = (3-methylbiphenyl + 4-methylbiphenyl)/dibenzofurane; m/z = 168; thermal maturity parameter [47].

5.3. Aliphatic hydrocarbons Due to relatively low combustion temperatures in domestic furnaces and incomplete combustion many biomarkers from the parent coal survived the process. They were found in the ash extracts. In most extracts aliphatic hydrocarbons predominate in chemical composition, particularly n-alkanes. Other compounds present such as steranes or pentacyclic triterpanes, and their distribution types are mainly related to the source fuel, i.e. bituminous coal. Compounds considered to be formed in combustion are minor components of the coal extracts. Light-weight compounds were not common, with the Orzesze domestic coal ash more often containing them than the Piekary S´la˛skie ash extracts. All Piekary S´la˛skie ash extracts contain elemental sulfur, possibly from pyrite present in the source coal. Coal waste extracts show composition common for coal wastes subjected to the process of self-heating, commonly occurring in coal waste dumps in Upper Silesia [38,39]. Only two slag wastes extracts show rather unique composition containing mainly aromatic hydrocarbons, possibly formed during burning.

5.3.1. n-Alkanes and acyclic isoprenoids Distributions of n-alkanes (m/z = 71) in the samples are variable. All coal ash extracts show a monomodal distribution of n-alkanes in the range from n-C13 to n-C35 with maxima of n-alkane concentration for n-C20–n-C24 in the case of the Orzesze furnace ash and for n-C27–n-C30 n-alkanes in the Piekary S´la˛skie furnace ash (Fig. 2a and b). In both ash types the outline of the n-alkane distribution is smooth without odd-over even carbon number atom predominance, expected as the biogenic feature inherited from the fuel source. Values of Carbon Preference Index (CPI) are close to 1.00 (Table 2) [40]. In all cases long-chain n-alkanes predominate over lighter compounds of this group. It is reflected by values of a ratio of long-chain(from n-C23 to n-C35) to short chain n-alkanes (from n-C13 to n-C22); R2/R1 in Table 2.n-Alkane distributions in coal wastes in more variable, monomodal, similar to ash extracts or bimodal with maxima in the n-C18–n-C20 and n-C27–n-C30 ranges (Fig 2c). While the Rydułtowy coal wastes (the W1 and W2 samples) show smooth monomodal distribution type without odd-over even carbon number atom predominance, n-alkane distributions of the

338

´ ska, D. Smółka-Danielowska / Fuel 102 (2012) 333–344 M.J. Fabian

Fig. 4. Sterane distribution in the extracts investigated (m/z = 217), (a) ash from the Orzesze domestic furnace (A22), (b) coal waste (W1) and (c) smelting waste (SW1).

Fig. 3. Distribution of pentacyclic triterpanes in the extracts (m/z = 191), (a) ash sample from the Orzesze domestic furnace (A10), (b) ash from the Piekary S´la˛skie domestic furnace (A15) and (c) coal waste (W1), (d) coal (C1); Ts = 18a(H)22,29,30-trisnorneohopane, Tm = 18a(H)-22,29,30-trisnorneohopane.

Janina and Maczki–Bór wastes extracts are more coal-like, bimodal with higher CPI values (Table 2). The previous investigations of coals from the Upper Silesia and Vistula Basins show similar variability in n-alkane distributions, with less mature distribution type for Vistula Basin coals and more mature distribution with low CPI values for Upper Silesia coals [22,32]. The SW1 slag extract did not contained n-alkanes at all while the SW2 n-alkanes show the very immature distribution with CPI value 3.22. That suggests contamination by recent organic matter probably soil covering some parts of the dump or vegetation particles such as pollens migrating from plants growing near the dump (woods, groves). The extract of flotation concentrate of bituminous coal from the Knurów Mine shows n-alkane distribution common for coals of this region [22,32]. n-Alkenes were absent in all extracts despite heat influence. Acyclic isoprenoids group (m/z = 71, 183) comprises mainly of two compounds: pristane and phytane present in variable contents. Apart from them only 4,7-dimethylundecane was found in the A10 ash extract. Values of pristane/phytane ratio (Pr/Ph) are higher than 1.00 in all Orzesze ash extracts, except of the A4 sample (Table 2). The Piekary S´la˛skie ash extracts show more various distributions of acyclic isoprenoids, with these compounds absent in many sam-

ples (Table 2). Pristane concentrations are often higher than n-heptadecane in the coal ash extracts while phytane concentrations are lower than n-octadecane. This is reflected by values of Pr/n-C17 and Ph/n-C18 ratios (Table 2). The first ones are mostly above 1.00, except the A1, A5, A11, A14, and A20 samples whereas the second below 1.00, except the A4, A14, A19, and A20 samples. Coal wastes show coal-like values of Pr/Ph ratio, Pr concentrations higher than that n-heptadecane and Ph concentrations lower than that n-octadecane (Table 2). Phytane concentrations are usually much lower than concentrations of n-octadecane. Sesquiterpanes and diterpanes (m/z = 123) were not found in the extracts. 5.3.2. Pentacyclic triterpanes Pentacyclic triterpanes (hopanes and moretanes) (m/z = 191) are present in the range from 18a(H)-22,29,30-trisnorneohopane (C27 abbreviated as Ts) to trishomohopanes (C33) (Fig. 3). Tetrakishomohopanes and pentakishomohopanes did not occur in the extracts. Such short distributions of hopanes are considered to be characteristic for coals and other terrestrial organic matter [43]. Some of ash extracts contain both 17a(H),21b(H) and 17b(H), 21a(H)-29-hopanes (moretanes), whereas in some cases ba diastereomers are absent. Biogenic 17b(H),21b(H) diastereomers of pentacyclic triterpanes were not found in the extracts investigated. This relatively mature distribution of pentacyclic triterpanes occurs in almost all Orzesze ash extracts, however, in some cases the distribution is thermally degraded and incomplete as in A1 and A3

´ ska, D. Smółka-Danielowska / Fuel 102 (2012) 333–344 M.J. Fabian

samples. Only a few Piekary ash extracts contained pentacyclic triterpanes (the A15, A17, A18 and A19 samples) and all of them show signs of heat changes (Fig. 3b). Organic matter present in coal wastes W1, W4 and W4 contained pentacyclic triterpanes with distribution similar to that found in bituminous coals accompanied by these wastes and to that presented in literature (e.g. [22]). 5.3.3. Steranes Steranes (m/z = 217) occur in only a few samples in the investigated ash extracts population (the A2, A4, A10, A21, and A22 samples) and generally in very low concentrations. This feature can be inherited from the source Upper Silesia coals in which extracts steranes are commonly absent or present only in low amounts [32] (Fig. 4). Among wastes only the Janina coal waste contained them. Complete sterane distribution was found in the extract of coal flotation concentrate. Surprisingly, they were also present in both slag extracts. These compounds distribution comprised predominantly stigmastane diastereomers (C29 steranes) with both 5a,14b,17b(H)and 5a,14a,17a(H)-stigmastanes occurring in the extracts. Ergostane (C28) and cholestane (C27) diastereomers were found in very low concentrations or they were absent as in the W1 sample (Fig. 3b).

339

5.4. Aromatic hydrocarbons The group of polycyclic aromatic hydrocarbons (PAHs) comprises compounds with two to five condensed aromatic rings such as naphthalene, phenanthrene, anthracene, fluoranthene, pyrene, benzo(ghi)fluorene, benzo(a)anthracene, chrysene, benzofluoranthenes, benzopyrenes and perylene (m/z = 128, 178, 202, 228, 252). The examples of polycyclic aromatic hydrocarbons distribution is shown in Fig. 5. These compounds are accompanied by their C1–C3 alkyl derivatives, except the SW1 sample (slag) where only unsubstituted PAHs were present. Lighter aromatic hydrocarbons (naphthalene and alkylnaphthalenes) show low concentrations in ash extracts. Naphthalene were not found in many extracts. This feature may be related both to heat influence (easy sublimation of the compound) or geochemical features of source bituminous coal. However, methyl-, dimethyl- , trimethyl- and phenylnaphthalenes were much more commonly found (Fig. 6). Phenanthrene, anthracene and their methyl derivatives are present in higher amounts, particularly in the Orzesze ash extracts (Fig. 5). In all extracts phenathrene shows the highest concentrations among PAHs. This feature is common in sedimentary organic matter since there are many biochemical precursors of this compound. For example, transformations paths of most diterpenoids end with phenanthrene [44–47]. Phenanthrene is often accompanied by anthracene, considered to be formed in combustion [44,46]. However, anthracene could also come from natural fires of mires being the sedimentary environment of biogenic organic matter of the USCB coals. Fig. 5d shows the PAHs distribution in the Knurów bituminous coal (C1). It is surprisingly rich in anthracene, present in the same amount as phenanthrene. The same feature was found in coals mined in other parts of the world which petrographic distribution is rich in inertinite macerals, particularly in pyro-fusinite and pyro-semifusinite (e.g. [21]). Since the investigated coal sample comes from flotation and comprised the cheapest fraction high anthracene concentration reflects enrichment of its maceral composition in inertinite. Apart from alkylnaphthalenes and alkylphenanthrenes also PAHs with 4–5 condensed rings were accompanied by their alkyl substituted derivatives, for example methyl- and dimethylpyrenes were also found. The A2 ash extract contained also a series of benzene derivatives substituted with short aliphatic chains. Among these compounds 1-ethyl-3-methylbenzene, three isomers of trimethylbenzene and 1-ethyl-4,5-dimethylbenzene were identified. 5.5. Polar groups-substituted compounds

Fig. 5. The example of polycyclic aromatic hydrocarbons distribution (m/ z = 128 + 178 + 202 + 228 + 252), (a) ash from the Orzesze domestic furnace (A11), (b) ash from the Piekary S´la˛skie domestic furnace (A18) and (c) coal waste (W1), (d) coal (C1); N = naphthalene, P = phenanthrene, A = anthracene, phN = phenylnaphthalene, Fl = fluorene, Py = pyrene, R = retene, B(ghi)F = benzo(ghi)fluorantene, BaA = benzo(a)anthracene, Ch = chrysene, BkF = benzo(k)fluoranthene, BaP = benzo(a)pyrene, BeP = benzo(e)pyrene, Pe = perylene.

Apart from aliphatic and aromatic hydrocarbons polar compounds of variable groups were found in several extracts. The main compound group are phenol (m/z = 94) and its derivatives such as 4methylphenol, 4-propylphenol, 3,4- and 3,5-dimethylphenol identified in A2, A5, and A10 coal ash extracts. These compounds most probably come from thermal destruction of vitrinite macromolecule since its phenolic units are considered to be of the lignin origin and were found both in coal pyrolysate or thermochemolysis products and in sedimentary organic matter containing vascular plants input [48–50]. The same origin can be assumed in the case of acetophenone, 2-methylbenzaldehyde or benzanthron (m/z = 230) found in the A2, A4 and A10 extracts. The source of furan derivatives found in some samples such as benzo(b)naphtho[2,3]furan and benzo(b) naphtho[2,1]furan (m/z = 218) are probably cellulose units present in a vitrinite macromolecule. However, it is also possible that some of phenolic compounds come from conifer wood such as pine which was used for fire kindling [51]. The same recent origin can be ascribed to several nitrogen compounds found in some coal ash extracts, mainly amines

340

´ ska, D. Smółka-Danielowska / Fuel 102 (2012) 333–344 M.J. Fabian

Fig. 6. Distributions of alkylnaphthalenes (m/z = 142 + 156 + 170) (I), methylphenanthrenes (m/z = 192) (II) and methylbiphenyls (m/z = 168) (III) in the investigated sample extracts; (a) ash from the Orzesze domestic furnace (A10), (b) ash from the Piekary S´la˛skie domestic furnace (A15), (c) coal waste (W1), (d) coal (C1); MNs = methylnaphthalenes; DMNs = dimethylnaphthalenes; TMNs = trimethylnaphthalenes, MPs = methylphenanthrene; DBF = dibenzofurane; MBs = methylbiphenyl.

and amides. The A2 sample contained several of them, such as Nmethyl-N-phenylformamide (in A4 too), N-methyl-N-nitrozobenzamine, and N-phenyl-formamide. N,N-dimethylbenzamine was found in the A2, A11, and A20 ash extracts, N-methyl-N-phenylbenzamine, N-(2-methylphenyl)acetamide in the A4, and A20, 4methylbenzamine in the A4, A6, and A7 extracts. One of the slag samples contained fatty acids. Probably they come from the soil cover of the Wełnowiec slag dump since the same sample contained also a series of n-alkenes and other unsaturated aliphatic compounds and its n-alkanes show high odd-over even carbon atom predominance, typical for immature organic matter of terrestrial origin [40]. 6. Discussion 6.1. Origin of organic compounds present in coal ash It was found that the compounds present in coal ash, slags and wastes extracts investigated have two origins. The first group of

them comes from the main source fuel, i.e. bituminous coal of the Upper Silesia Coal Basin. The second group of compounds was formed in combustion process or their distributions have changed under the influence of heat. However, it is not always easy to identify the particular group which a given compound belongs to. Most of organic compounds found in domestic ash (A1–A19) show features indicating the USCB bituminous coals as their origin. Often biomarker distributions are unchanged or only slightly changed by heat comparing to those of the source coal investigated. Such biomarkers as steranes, or pentacyclic terpanes obviously come from unburnt particles of coal present in ash or were evaporated at the beginning of combustion and next adsorbed by ash particles. The complex composition of the coal waste extracts (W1–W4) is related to the source coals which underwent the self-heating process. These extracts contain mixtures of pyrolytically released compounds and mostly unchanged by heat biomarkers. The similar results were found for other self-heated coal wastes [38,39] as described in Section 6.2. Generally, due to more

´ ska, D. Smółka-Danielowska / Fuel 102 (2012) 333–344 M.J. Fabian

complete combustion and higher temperature industrial ash organic matter (A20–A22) and slag (SW1, SW2) is much more difficult to interpret since many compounds are absent or occur only in low concentrations. Despite much better combustion conditions in industrial furnaces than in domestic ones, the industrial coal ash extracts contained a wide range of biomarkers, particularly the A22 sample from the Halemba power plant. Thus biomarkers present in these samples show features of source fuel. Comparing to steranes and hopanes it is more difficult to conclude about the origin of n-alkanes since both domestic furnaces utilized bituminous coal of relatively high rank among the Upper Silesian coals [22,32]. In their organic matter, the processes of natural maturation caused such features as CPI values near 1.0 (Table 2) and a smooth monomodal outline of the n-alkanes distributions (Fig. 2). These features overlap with changes caused by coal combustion. In some sample extracts n-alkanes show distributions similar to the coal distribution (the A2, A4, A5, A7, A10, A11, A16, A20, and A22 samples), sometimes even with slight odd-over-even carbon number predominance preserved (elevated CPI values in A5, A16, A20, and A22 samples, Table 2). Odd-over-even predominance in the range of long-chain n-alkanes (n-C24–n-C33) is a feature inherited directly from the distributions of fatty acids occurring in cuticular waxes of vascular plants. These fatty acids commonly show even-over-odd carbon number atom predominance in their distribution; after defunctionalisation and a loss of one carbon atom, they change into n-alkanes [40,43,52]. Odd-over-even predominance in n-alkanes tends to decrease with increasing thermal maturity of organic matter and usually organic matter with vitrinite reflectance > 1.0 also show CPI values 1.0 and a smooth outline of the n-alkane distribution [40]. In some ash extracts n-alkane distribution is clearly changed by heat, with the removal of lighter n-alkanes as the most obvious effect seen (the A1, A3, A6, A8, A9, A12, A13, A14, A15, A17, A18, and A19 samples) (Fig. 2). Comparing to n-alkanes present in the Knurów coal extract (C1) and other coals of the region [22,30] the distribution in these samples comprises less compounds, e.g. n-C20–n-C31 instead of n-C13–n-C35 as it is in Fig. 2. Apart from the removal of light-weight compounds, the distribution usually shows the Gaussian outline of chromatographic peaks, possibly related to the input of n-alkanes pyrolytically released from coal macromolecule (Fig. 2a and b). These changes are much more extensive than those seen in self-heated coal wastes both analyzed here (the W1–W4 samples) or investigated previously [38,39]. Pristane (Pr) and phytane (Ph) are compounds commonly applied in organic geochemistry to assess oxicity of depositional environment [41,42]. Their ratio values > 1.0 are considered a clue to oxic whereas values < 1.0 to anoxic environment of deposition. However, in the case of coals the relatively high values of Pr/Ph ratio do not indicate highly oxic depositional environment but rather reflect a high input of vascular plant material in organic matter. In the case of terrestrial organic matter there are other precursors of pristane than chlorophyll, such as a-tocopherol. They increase the final pristane concentration in organic matter [42]. Most of Pr/Ph values shown in Table 2 confirm predominating terrestrial source of primary organic material and indicate bituminous coals as a source fuel. However, Pr/Ph values are surprisingly low for the A4, A14, A17 and A20 samples (0.60) and Pr is absent in some of the extracts, (A12, A13, A16, A18, A21, W2, and SW1). Particularly in the Piekary S´la˛skie and industrial coal ash extracts Pr and Ph distribution are affected, possibly due to better combustion. Comparing to n-alkanes, pentacyclic triterpanes (hopanes and moretanes) in ash and coal waste extracts show the distributions almost unchanged by heat, very similar to that found in coals of the region (Fig. 3 and [22,30]). These compounds, deriving from bacteria, are relatively abundant in most of extracts (except A6,

341

A12, A13, A16, A20, W2, W3), and seem to be the most useful diagnostic biomarker group to indicate presence of fossil fuel organic matter. Short distributions of hopanes, without tetrakishomohopanes (C34 hopanes) and pentakishomohopanes (C35 hopanes) present, are considered to be characteristic for coals and other terrestrial organic matter whereas longer pentacyclic triterpane distributions, up to C35, are ascribed to marine organic matter [43]. The distribution included only geochemical diasteromers 17a,21b(H)- (abbrev. as ab hopanes) and 17b,21a(H)- (abbrev. as ba hopanes or moretanes) without 17b,21b(H)- biochemical (abbrev. as bb) diasteromers found (Fig. 3). It was described in literature [22,30,32] that bb hopanes occur in the USCB extracts but generally these mined in the eastern part of the basin where vitrinite reflectance values are in the range 0.5–0.9% [53,54]. Moreover, values of hopane maturity parameters do not reflect combustion influence but are very close to those of coal extract (Table 2), as it is described in Section 6.2. Despite very low concentrations of steranes their distributions show clearly their relationship to source bituminous coal. Wherever they are present in the extracts (the A2, A5, A10, A22, W1, W3 and SW1 samples), their distributions are uniformly dominated by sigmastane diastereomers (C29) as it was found in the C1 coal sample and was described in other papers presenting the USCB coals geochemistry [22,30,32]. Such distribution is commonly found in coals of different age and rank, and is considered to be related to terrestrial organic matter deriving from higher vascular plants producing mainly C29 sterols such as b-sitosterol [29,43,55]. 6.2. Maturity and heat-related changes in biomarker distributions Geochemical features of the ash extracts investigated are a mixture of features of the parent coal type and heat influence caused by combustion. According to the range of heat the changes in all ash extracts population can be divided into two subpopulations of samples, the first, less thermally altered, coming from the Orzesze domestic furnace (the A1–A11 samples) and the second from the Piekary S´la˛skie (the A12–A19 samples) which shows much larger changes. Both domestic furnaces applied coals of the similar calorific values and ash contents. It follows that the differences in ash extract composition are related to differences in construction of both domestic furnaces. While in both furnaces temperature of

Fig. 7. Pr/n-C17 versus Ph/n-C18values for the Upper Silesia coal ash and coal waste extracts; Pr = pristane, Ph = phytane.

342

´ ska, D. Smółka-Danielowska / Fuel 102 (2012) 333–344 M.J. Fabian

Fig. 8. Pr/n-C17 versus Pr/Ph values for the Upper Silesia coal ash and coal waste extracts (modified Hunt diagram, 1996); Pr = pristane, Ph = phytane.

flame is similar (270 °C) they differ in the chimneys height. The higher chimney in the Piekary S´la˛skie furnace, giving better oxygenation and higher temperature in the furnace combustion zone, has also caused lower preservation of biomarkers in the coal ash samples investigated and higher variability in values of biomarker parameters (Table 2). This reflects higher heat influence on the occurrence and distributions of organic compounds present in the Piekary S´la˛skie ash extracts. It is much more difficult to find such trends in the case of industrial ash (A20–A22), coal waste (W1–W3), and slag (SW1, SW2) extracts since the sample populations are not numerous. However, there is an overall similarity between features of organic matter present in industrial and domestic ash, despite differences in combustion mode, whereas coal waste and slag samples extracts features vary greatly, both in respect of biomarkers present and values of maturity parameters. Both domestic furnaces used a coal type of relatively advanced maturity reaching the middle of catagenesis. In this part of the Silesia Coal Basin Rf values are higher than 0.8%, sometimes even reach 1.0% [22,54]. It follows that maturity biomarker parameters are less sensitive to the heat of combustion since they have reached the diasteromerization equilibrium, i.e. their validity limit. However, the several changes in their values can be pointed out. Low values of CPI (1.1), found in most of coal ash samples, both domestic and industrial (Table 1), seem to be a feature inherited from the parent bituminous coal rather than heat-related [40]. However, some of these samples show a characteristic Gaussian outline of the n-alkane peaks (Fig. 2a and b). Such distribution was described in literature for coals changed by heat of an igneous intrusion, coal pyrolysates, and self-heated coal wastes [23,31,38,39]. It can testify local pyrolytical conditions in the combustion zone, i.e. oxygen deficiency. It is more difficult to explain high CPI values found in the SW2 and W3 samples (>3.0). It is possible that material stored in waste dumps became contaminated by recent plant material containing n-alkanes with high odd-over-even carbon number predominance what affected CPI values. The removal of lighter n-alkanes caused by heat influence is well seen in most of distributions of n-alkanes (1). In most of the Piekary S´la˛skie coal ash extracts (A12-A19) the process concerns the wider range of compounds which follows that distributions shows a maximum of distribution for longer-chain n-alkanes than it is for the Orzesze ash extracts (A1–A11) (n-C27–n-C30 and n-C20–

n-C24, respectively). The industrial ash samples (A20 and A22) show the opposite effect, with short chain n-alkanes dominating in distribution. This feature can be related to higher temperature of combustion which caused thermal destruction of long-chain nalkanes. The same can be true for the A21 and SW1 samples which extracts did not contained any n-alkanes at all. The most advanced heat changes are seen in contents of pristane, phytane and lighter n-alkanes. They are reflected by values of Pr/Ph, Pr/n-C17 and Ph/n-C18 ratios (Table 2). The modified Hunt diagram [56] in Fig. 7 shows that along the line of kerogen III/humic coals the less heat-affected samples are projected. With the increasing temperature influence the samples shift to the area of lower values of Pr/n-C17 and higher values of Ph/n-C18 ratio. The direction is indicated by the arrow on the diagram. In Fig. 8 there are shown changes in values of Pr/Ph ratio versus Pr/n-C17 ratio reflecting combustion influence. High Pr/Ph and Pr/n-C17 values are typical for Upper Silesia bituminous coals (the Knurów coal sample – C1) and coal wastes (W1–W4). In this area of the diagram there are also the Orzesze coal ash extracts which show the best preservation of the original biomarkers. The Piekary S´la˛skie ash extracts are characterized with lower pristane concentrations and their samples are projected in the left lower part of the diagram. Values of the ratio of 17a(H),21b(H)-homohopane 20S to the sum of 20S and 20R diastereomers are about 0.56, which is considered to be the limit of its validity (Table 2) [43,57]. This well corresponds to the rank of the parent USCB coals and was also described by other authors characterizing their geochemistry [22,30,32]. The same correlation with source fuel is shown by a ratio of moretanes to hopanes (baab + ab) in Table 2. It is described in geochemical literature that concentrations of moretanes (ba hopanes) decrease with increasing organic-matter maturity [54]. Moretane to hopane ratio values are 0.26 for almost ash samples, both domestic and industrial ones (Table 2), and this value is close to that found for other USCB coals. One of important features caused by heat is the absence of Ts and Tm in some of the distributions (the A1 and A3 samples) and the visible decrease in their contents comparing to the other hopanoids (Fig. 3). The similar effect has been found in selfheated coal wastes of the region investigated previously [38,38]. The removal of lighter compounds in coal ash extracts, seen in the n-alkene distributions, is also present in some distributions of alkylnaphthalenes and alkylphenanthrenes (Fig. 5). Alkylnaphthalenes were partially or totally removed in many of the ash, coal waste and slag samples. This particularly concerns methylnaphthalenes absent in the A1, A3–A6, A8, A9, A12–A14, A16–A18, A20, A21, W2, and SW1 samples. Such removal caused high variability of maturity parameters [58–61] basing on alkylnaphthalenes and generally made them unsuitable as indicators for identification of source organic matter in coal ash (Table 2). For example, dimethylnaphthalene ratio (DNR) values range from 0.95–2.75 comparing to 1.69 for the source coal (C1). However such variability can be applied to asses heat influence for these samples in which dimethylnaphthalenes can be found. The same seems to be true for the highly variable methylbiphenyl-basing ratio. The Methylphenanthrene Index (MPI-3, [61]) values seem to be much more uniform than those of alkylnaphthalenes, particularly for the Orzesze samples, on average 0.95, which is very close to the MPI-3 value for the Knurów bituminous coal (C1) (0.90, Table 2). However, methylphenanthrenes were absent or present in very low amounts in the Piekary S´la˛skie coal ash extracts, so only for two samples it was possible to calculate this parameter.

7. Conclusions Geochemical features of the USCB coal ash extracts are derived from features of the parent coal type and heat influence caused by

´ ska, D. Smółka-Danielowska / Fuel 102 (2012) 333–344 M.J. Fabian

combustion in domestic furnaces. Several groups of biomarkers are well preserved in coal ash extracts such as n-alkanes, steranes and pentacyclic triterpanes, despite combustion. Their distributions show features enabling to identify the source fuel as a bituminous coal. Values of biomarker parameters show relatively minor changes due to heat of the combustion process. The most extensive changes are found in the relative contents of pristane, phytane, lighter n-alkanes, and alkylnaphthalenes. The heat influence is reflected by in changes values of Pr/Ph, Pr/n-C17, Ph/n-C18, and DNR-2 ratios. Much less extensive changes are seen in distributions of pentacyclic triterpanes which make them the most useful biomarker group for source fuel characterization. Since steranes were absent in many USCB coal ash extracts it was not possible to apply them in most samples, but wherever they are present they show distributions directly related to source fuel, both in respect of maturity parameters and stigmastane diastereomers (C29) dominating in the distribution. Comparing to ash extracts the coal wastes subjected to selfheating show higher extractability, wider ranges of biomarkers with higher variability in their distributions. Geochemical features of slag extracts also vary widely from the extract containing PAHs as the only components to that containing biomarker groups similar to those found in other samples. Domestic furnaces are characterized by low temperature of combustion (assessed to be around 270 °C). This means that coal ash contained unburnt particles of source coal and/or the main part of extractable organic matter adsorbed on the ash minerals was evaporated at relatively low temperatures. A higher chimney of the Piekary S´la˛skie furnace caused better oxidation of coal and more advanced alteration of biomarkers distributions comparing to relatively well preserved biomarkers in the Orzesze coal ash. Comparing to the domestic furnace ash, extracts of ash from the power plants are poorer in biomarkers, particularly that from the Tychy plant in which only n-alkanes were found. However, even in the case of industrial ash it was possible to find a range of biomarkers which can be applied for geochemical characterization of the source fuel. References [1] Franco A, Diaz AR. The future challenges for ‘‘clean coal technologies’’: joining efficiency increase and pollutant emission control. Energy 2009;34:348–54. [2] Querol X, Umana J, Alastuey A, Lopez-Soler A, Plana F. Extraction of soluble major and trace elements from fly ash in open and closed leaching systems. Fuel 2001;80:801–13. [3] Bailey JG. The origin of unburnt combustibles in coal. The University of Newcastle, NSW, Unpublished Ph.D. Thesis; 1992. [4] Goodarzi F, Peel WP, Brown J, Charland JP, Huggins F, Percival J. Elemental concentration and speciation, polyaromatic hydrocarbons and mineralogical characteristics of milled-coal and ashes from the Unit #5 at Battle River Station. Bull Geol Surv Canada 2002;570:148. [5] Goodarzi F. Petrology of subbituminous feed coal as guide to capture of mercury by ESP – Influence of depositional environment. Int J Coal Geol 2005;61:1–12. [6] Den Boer E, Je˛drczak A, Kowalski Z, Kulczycka J, Szpadt R. A review municipal solid waste composition and quantities in Poland. Waste Manage 2010;30:369–77. [7] Wójcik M, Smołka-Danielowska D. Phase minerals composition of wastes formed in bituminous coal combustion from individual domestic furnace in the Piekary S´la˛skie Town (Poland). Pol J Environ Stud 2008;17:817–21. [8] Grodzin´ska-Jurczyk M. Management of industrial and municipal solid wastes in Poland. Resour Conserv Recy 2001;32:85–103. [9] Jones RB, McCourt CB, Morely C, King K. Maceral and rank influences on the morphology of coal char. Fuel 1985;64:1460–7. [10] Oka N, Murayama T, Matsuoka H, Yamada T, Shinozaki S, Shibaoka M, et al. The influence of rank and maceral composition on ignition and char burnout of pulverized coal. Fuel Process Technol 1987;15:213–24. [11] Alonso MJG, Borrego AG, Alvarez D, Parra JD, Menéndez R. Influence of pyrolysis temperature on char optical texture and reactivity. J Anal App Pyrolysis 2001;58–59:887–909. [12] Grin A, Marsh H. Carbonization of coal blends mesophase formation. Fuel 1981;60:1115–20. [13] Hower JC, Maroto-Valer M, Taulbee DN, Sakulpitakphon T. Mercury capture by distinct fly ash carbon forms. Energy Fuels 2000;14:224–6.

343

[14] Maroto-Valer MM, Taulbee DN, Hower JC. Characterization of differing forms of unburned carbon present in fly ash separated by density gradient centrifugation. Fuel 2001;80(6):795–800. [15] Oros DR, Simoneit BRT. Identification and emission rates of molecular tracers in coal smoke particulate matter. Fuel 2000;79:515–36. [16] Simoneit BRT, Elias VO. Organic tracers from biomass burning in atmospheric particulate matter over the ocean. Marine Chem 2000;69:301–32. [17] Simoneit BRT. Biomass burning – a review of organic tracers for smoke from incomplete combustion. Appl Geochem 2002;17:129–62. [18] Fabbri D, Marynowski L, Fabian´ska MJ, Simoneit BRT, Zaton´ M. Levoglucosan and other cellulose markers in pyrolysates of miocene lignites: geochemical and environmental implications. Environ Technol Sci 2008;42:2957–63. [19] Disnar JR, Harouna M. Biological origin of tetracyclic diterpanes, n-alkanes and other biomarkers found in lower carboniferous gondwana coals (Niger). Org Geochem 1994;21:143–52. [20] Ehinola OA, Ekweozor CM, Oros DR, Simoneit BRT. Geology, geochemistry and biomarker evaluation of lafia-obi coal, benue trough. Nigeria Fuel 2002;81:219–33. [21] Fabian´ska MJ, Kruszewska KJ. Relationship between petrographic and geochemical characterisation of selected South African coals. Int J Coal Geol 2003;54:95–114. [22] Kotarba MJ, Clayton JL. A stable carbon isotope and biological marker study of Polish bituminous coals and carbonaceous shales. Int J Coal Geol 2003;55:73–94. [23] Amijaya H, Schwarzbauer J, Littke R. Organic geochemistry of the lower Suban coal seam, South Sumatra Basin, Indonesia: palaeoecological and thermal metamorphism implications. Org Geochem 2006;37:261–79. [24] Stout SA, Emsbo-Mattingly SD. Concentration and character of PAHs and other hydrocarbons in coals of varying rank – implications for environmental studies of soils and sediments containing particulate coal. Org Geochem 2008;39:801–19. [25] Kotas A, Porzycki J. Major features of carboniferous coal basins in Poland. Prz Geol 1984;32:268–80. [26] Kotas A. Upper Silesian Coal Basin. In: Osika R, editor. Geology of Poland, vol. 6. Mineral Deposits. Warsaw: Wydawnictwa Geologiczne; 1990, p. 77–93. [27] Knafel S. Petrographic descriptions of selected coals from the lublin and the Upper Silesian Coal Basins. In: Bojkowski K, Porzycki J, editors. Geological problems of coal basins in Poland. Warsaw: Geological Institute Press; 1983. p. 285–333. [28] Gabzdyl W, Probierz K. The occurrence of anthracites in an area characterized by lower rank coals in the Upper Silesian Coal Basin of Poland. Int J Coal Geol 1987;7:209–25. [29] Kruszewska K. Microfacies types of coal seams in Upper Silesian Coal Basin. Geol Quarter 1983;27:41–58. [30] Kotarba MJ, Clayton JL, Rice DD, Wagner M. Assessment of hydrocarbon source rock potential of Polish bituminous coals and carbonaceous shales. Chem Geol 2002;184:11–35. [31] Fabian´ska M, Matuszewska A. Preliminary geochemical analysis of coal extracts and low-temperature tars of the Upper-Vistula Coal Region (Poland). Pol J Appl Chem 1998;3(4):259–74. [32] Fabian´ska MJ, Bzowska G, Matuszewska A, Racka M, Skre˛t U. Gas Chromatography–mass spectrometry in appraisal of organic matter of the grodziec beds (Upper Carboniferous): Upper Silesian Coal Basin (Poland). Chemie der Erde (Geochemistry) 2003;63:63–91. [33] Wu T, Gong M, Lester E, Wang F, Shou Z, Yu Z. Characterisation of residual carbon from entrained-bed coal water slurry gasifiers. Fuel 2007;86:972–82. [34] Xu Sh, Zhou Z, Gao X, Yu G, Gong X. The gasification reactivity of unburned carbon present in gasification slag from entrained-flow gasifier. Fuel Proces Technol 2009;90:1062–70. [35] Smołka-Danielowska D. Phase composition studies of coal ash from the individual domestic furnaces and their environmental impact. Zeszyty Naukowe Politechniki S´la˛skiej 2001;249:157–64. [36] Philp RP. Fossil fuel biomarkers. In: Application and spectra. Amsterdam: Elsevier; 1985. [37] The Wiley/NBS registry of mass spectral data. New York: Wiley; 2000. [38] Misz M, Fabian´ska M, C´miel S. Organic components in thermally altered coal waste: preliminary petrographic and geochemical investigations. Int J Coal Geol 2007;71:405–24. [39] Misz-Kennan M, Fabian´ska M. Thermal transformation of organic matter in coal waste from Rymer Cones (Upper Silesian Coal Basin, Poland). Int J Coal Geol 2010;81:343–58. [40] Bray EE, Evans ED. Distribution of n-paraffins as a clue to recognition of source beds. Geochim Cosmochim Acta 1961;22:2–15. [41] Didyk BM, Simoneit BRT, Brassell SC, Eglington G. Organic geochemical indicators of palaeoenvironmental conditions in sediment. Nature 1978;272:217–22. [42] ten Haven HL, de Leeuw JW, Rullkotter J, Sinninghe Damste JS. Restricted utility of the pristane/phytane ratio as a palaeoenvironmental indicator. Nature 1987;330:641–3. [43] Peters KE, Walters CC, Moldowan JM. The biomarker guide. In: Biomarkers and isotopes in petroleum exploration and earth history. Cambridge: Cambridge University; 2005. [44] Simoneit BRT. Biomarker PAHs in the environment. In: Neilson AH, editor. The handbook of environmental chemistry, PAHs and related compounds, vol. 3. Berlin: Springer-Verlag; 1998. p. 176–221. Part I.

344

´ ska, D. Smółka-Danielowska / Fuel 102 (2012) 333–344 M.J. Fabian

[45] Fabian´ska M. Organic geochemistry of brown coal of the selected Polish basins. Katowice: University of Silesia; 2007. ISBN 978-83-226-1622-2. (in Polish). [46] Pereira WE, Hostettler FD, Luoma SN, van Geen A, Fuller CC, Anima RJ. Sedimentary record of anthropogenic and biogenic polycyclic aromatic hydrocarbons in San Francisco Bay (California). Marine Chem 1999;64:99–113. [47] Alexander R, Cumbers KM, Kagi RI. Alkylbiphenyls in ancient sediments and petroleum. Org Geochem 1986;10:841–5. [48] Clifford DJ, Carson DM, McKinney DE, Bortiatynski JM, Hatcher PG. A new rapid technique for the characterisation of lignin in vascular plants: termochemolysis with tetramethylammonium hydroxide (TMAH). Org Geochem 1995;23(2):169–75. [49] Saiz-Jimenez C, de Leeuw JW. Lignin pyrolisis products: their structures and their significance as biomarkers. Org Geochem 1985;10:869–76. [50] Hatcher PG, Faulon J-L, Wenzel KA, Cody GD. A structural model for ligninderived vitrinite from high-volatile bituminous coal (coalified wood). Energy Fuels 1992;6:813–20. [51] Cotrim da Cunha L, Serve L, Gadel F, Blazi J-L. Lignin-derived phenolic compounds in the particulate organic matter of a French Mediterranean river: seasonal and spatial variations. Org Geochem 2001;32:305–20. [52] Tissot BP, Welte DH. Petroleum formation and occurrence. Berlin: SpringerVerlag; 1984.

[53] Jurczak-Drabek H. Petrographical atlas of coal deposits Upper Silesian Coal Basin. Warsaw: Polish Geological Institute; 1996. [54] Jureczka J, Kotas A. Coal deposits. Upper Silesian Coal Basin. In: Zdanowski A, _ Zakowa H, editors. The carboniferous system in Poland, vol. 148. The works of Polish Geological Institute; 1995. p. 164–73. [55] Huang W-Y, Meinschein WG. Sterols as ecological indicators. Geochim Cosmochim Acta 1979;43:739–75. [56] Hunt JM. In: Petroleum geochemistry and geology. New York: WH Freeman & Company; 1996. [57] Seifert WK, Moldowan JM. Use of biological markers in petroleum exploration. In: Johns RB, editor. Methods in geochemistry and geophysics, vol. 24; 1986. p. 261–90. [58] Radke M, Rullkotter J, Vriend SP. Distribution of naphthalenes in crude oils from the Java Sea: source and maturation effects. Geochim Cosmochim Acta 1994;58:3675–89. [59] Radke M, Willsch DH, Leythaeuser D. Aromatic components of coal: relation of distribution pattern to rank. Geochim Cosmochim Acta 1982;46:1831–48. [60] Radke M. Organic geochemistry of aromatic hydrocarbons. Advances in petroleum geochemistry, vol. 2. London: Academic Press; 1987. p. 141–203. [61] Radke M, Welte DH. The methylphenanthrene index (MPI): a maturity parameter based on aromatic hydrocarbons. In: Advances in, organic geochemistry; 1981. p. 504–12.