www.elsevier.com/locate/ijcoalgeo
International Journal of Coal
Mode of occurrence of trace elements in the Pellana lignite
(SE Peloponnese, Greece)
A. Chatziapostoloua, S. Kalaitzidisa, S. Papazisimoua, K. Christanisa,*, D. Vagiasb
aSection of Earth Materials, Department of Geology, University of Patras, GR-26500 Rio-Patras, GreecebInstitute of Geological and Mineral Exploration, Ag. Vassiliou Square 21, GR-21100 Tripoli, Greece
Received 31 May 2004; received in revised form 22 February 2005; accepted 3 April 2005
Available online 15 June 2005
Abstract
Mineralogical and geochemical analyses of the Pellana lignite (SE Peloponnese, Greece) were carried out in order to predict
the mode of occurrence of trace elements and their mobility during lignite combustion for power generation. Lignite and ash
samples (after combustion at 750 8C) of two cores from this deposit were examined. The mean ash content is 30% to 43% and C
contents on dry, ash-free basis range from 45% to 60%, respectively. The mineral phases contained in the lignite are quartz, K-
feldspars, mixed-layer clays (illite-rich), micas, gypsum and pyrite. Factor analysis on geochemical data shows that the elements
As, Ba, Mn, Mo, Sb, Se, Sr, U and V have both organic and inorganic affiliation. To study the mobility of each element during
combustion, the relative enrichment factor was calculated. The most depleted and hence the most mobile elements, proved to be
Hf, Nb and Sb, while Se, Ba and Bi are moderately depleted. In case of the Pellana lignite utilization we should expect
environmental problems associated with the elements As, Ba, Bi, Hf, Mn, Mo, Nb, Sb and Se. These elements may be either
volatilized during combustion or leached from fly ash-disposal areas into underground waters, causing severe environmental
and health impacts.
D 2005 Elsevier B.V. All rights reserved.
Keywords: Environment; Greece; Pellana lignite; Mineralogy; Trace elements
1. Introduction
Many studies on the geochemical features of the
trace elements contained in coal have been carried out
in order to understand and evaluate the mode of
0166-5162/$ - see front matter D 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.coal.2005.04.005
* Corresponding author. Tel.: +30 2610997568; fax: +30
2610997560.
E-mail address: [email protected] (K. Christanis).
occurrence of the trace elements, as well as their
behavior during combustion (e.g., Finkelman, 1994;
Meij, 1995; Swaine, 1995; Davidson, 2000; Vassilev
et al., 2001). The mode or form of occurrence of the
elements may control the potential hazardous effects
to human health and the environment. Various indirect
methods have been applied for the determination of
the modes of occurrence of trace elements in coal such
as float-sink, leaching and statistical analyses (Hug-
gins, 2002 and references herein). Also, in Greece, a
Geology 65 (2006) 3–16
A. Chatziapostolou et al. / International Journal of Coal Geology 65 (2006) 3–164
number of studies have focused on the mineral matter
and trace element contents in Greek lignites and peats,
as well as on the behavior of trace elements during
combustion (Foscolos et al., 1989, 1998; Filippidis
and Georgakopoulos, 1992; Georgakopoulos et al.,
1994, 2002; Filippidis et al., 1996; Sakorafa et al.,
1996; Christanis et al., 1998; Kalaitzidis and Christa-
nis, 2000, 2002; Georgakopoulos, 2001; Iordanidis et
al., 2001; Kalaitzidis et al., 2002).
In this study we present geochemical data from the
Pellana lignite deposit (SE Peloponnese). The exploi-
tation of this deposit could be economically feasible,
since it is located in the vicinity of the Megalopolis
Lignite Center, being the second largest power-plant
infrastructure in Greece. In a previous study of the
Pellana lignite, the focus was on the differences of the
element contents being determined after digestion in
both closed vessels using microwave furnace and
open vessels. It has been revealed that the concentra-
tions of As, Ba, Be, Co, Cr, Mn, Mo and V, which are
KP-7
KP-13
10 2 km
37 13'0
37 12'0
22 18'0 2
Pellana
Fig. 1. Simplified geological map of th
considered as hazardous air pollutants, were signifi-
cantly depleted during the open vessel digestion
(Chatziapostolou et al., in press).
The object of the present study is to estimate the
organic/inorganic affiliation of the trace elements
contained in the Pellana lignite in order to assess
their behavior in case of exploitation for power gen-
eration. Interpretations of element-volatilization fates
based on statistical analysis are compared with calcu-
lated mobilization data that were obtained from geo-
chemical analyses of both bulk lignites and their
respective ashes.
2. Geological setting
The intermontane Pellana basin is located in the
Prefecture of Lakonia, in SE Peloponnese (Greece)
and occupies an area of 25 km2 (Fig. 1). The Pre-
Neogene basement and the margins of the basin con-
PRE-NEOGENE BASEMENT
Limestones and flysch sediments
Thrust fault
Normal fault
Alluvial sediments
Scree and talus cones
HOLOCENE
Alluvial fans
PLEISTOCENE
Fluvio - terrestrial sediments
PLIOCENE-LOWER PLEISTOCENE
Alternations of fluvial, terrestrialand limnic sediments
Lacustrine sediments
Legend
2 21'0
Greece
Study area
e Pellana basin (Georgiou, 2001).
A. Chatziapostolou et al. / International Journal of Coal Geology 65 (2006) 3–16 5
sist mainly of limestones and flysch sediments. The
sediments filling the basin are of limnic and fluvio–
terrestrial origin, of Upper Pliocene to Middle Pleis-
tocene age (Georgiou, 2001). The limnic sediments
(clay, marl and silt) occupy the northern and the
eastern parts of the Pellana basin and host a lignite
seam. The lignite seam is constituted from twelve
lignite leafs, the thickness of which ranges from few
cm in the southern part up to 12.35 m (in total) in the
northern part. The reserves amount to 30.8 Mt, 26.4
Mt of which are exploitable (Vagias, 2001).
3. Materials and methods
Twenty two lignite samples were collected from
two cores (KP-7 and KP-13, see Fig. 1 and Table
1). The lignite samples were air-dried, crushed to
pass through the 250 Am sieve and then homoge-
nized. Ash contents were determined after combus-
tion at 750 8C for 4 h using a Raypa HM9 muffle
Table 1
Ash and C, H, N, O, Stotal contents (wt.%) of the Pellana bulk-lignite sa
determined in the 750 8C ashes]
Sample Depth (m) Asha Ca Ha Na
KP-13/3 73.55–73.63 67.9 16.6 1.7 0.2
KP-13/5 73.70–73.85 34.5 35.8 3.1 0.6
KP-13/8 99.65–99.75 18.5 47.9 4.0 1.1
KP-13/11 99.88–99.98 17.3 49.9 3.8 0.8
KP-13/13 100.00–100.10 13.8 51.6 4.0 0.9
KP-13/16 100.21–100.43 18.8 48.6 3.8 1.0
KP-13/23 101.15–101.30 39.5 35.1 3.2 0.9
KP-13/27 101.65–101.75 20.1 46.6 3.7 0.7
KP-13/31 102.05–102.15 17.4 49.3 3.9 0.9
KP-13/43 103.25–103.35 30.9 40.0 3.3 1.2
KP-13/47 108.55–108.70 42.4 34.1 2.9 0.8
KP-13/51 109.00–109.10 18.4 48.5 3.9 1.0
KP-13/59 109.85–110.00 29.3 41.4 3.6 0.9
KP-13/61 110.15–110.30 51.2 24.1 2.5 0.4
KP-7/3 60.75–60.93 29.0 40.2 3.7 0.9
KP-7/7 61.20–61.40 35.0 37.1 3.2 0.7
KP-7/8 61.40–61.50 37.9 34.2 3.3 0.8
KP-7/14 62.05–62.15 30.8 37.7 3.5 0.8
KP-7/18 62.60–62.80 38.3 33.4 3.3 0.9
KP-7/21 63.07–63.19 72.4 12.4 1.5 0.4
KP-7/22 63.19–63.30 51.2 26.2 2.4 0.3
KP-7/25 63.55–63.75 51.1 25.1 2.7 0.7
a On dry basis.b On dry ash-free basis.c On 100% ash basis.
furnace, according to ASTM D3174 (1989). Ulti-
mate analysis on the lignite samples and their ashes
was performed using the Carlo Erba EA1108 CHNS
analyzer. Mineralogical analysis of the ashed (at 750
8C) samples was carried out using a Philips
PW1050 X-ray diffractometer. Geochemical analy-
ses were performed at the ACTLABS Laboratories,
Ancaster, Canada. The lignite samples were digested
in microwave furnace and the ashed samples in
open vessels using aqua regia (HNO3 and H2SO4).
The concentrations of Al, Fe, Ca, Mg, K, Na, Ba,
Cr, Mn, Sr, V, Zn and Zr were determined using
Inductively Coupled Plasma-Atomic Emission Spec-
trometry (ICP-AES), and these of As, Be, Bi, Cd,
Ce, Co, Cs, Cu, Eu, Ga, Hf, La, Li, Lu, Mo, Nb,
Nd, Ni, Pb, Rb, Sb, Se, Sm, Sn, Tb, Te, Th, Tl, U,
Y and Yb using Inductively Coupled Plasma-Mass
Spectrometry (ICP-MS). Since the digestion method
proved to be problematic for determining the Zr
concentration, the results for this element are treated
with skepticism.
mples [Oxygen: calculated as O=100� (ash+C+H+N+S)db, Sash:
Oa Cb Hb Nb Ob Stotala Sash
c
11.2 51.8 5.2 0.5 34.9 2.4 1.5
21.2 54.6 4.8 0.9 32.4 4.8 0.4
25.2 58.8 5.0 1.3 30.9 3.2 10.6
25.5 60.3 4.6 1.0 30.8 2.7 10.8
27.5 59.8 4.6 1.0 31.9 2.3 5.5
24.5 59.9 4.7 1.2 30.2 3.3 13.4
18.5 58.0 5.3 1.5 30.5 2.8 2.6
25.5 58.4 4.6 0.9 32.0 3.3 6.9
25.7 59.7 4.8 1.1 31.1 2.7 11.4
22.2 57.4 4.7 1.7 31.9 3.0 4.7
18.1 59.3 5.1 1.4 31.4 1.6 2.7
27.0 59.5 4.8 1.2 33.1 1.1 3.5
21.5 58.5 5.1 1.3 30.5 3.3 4.4
16.3 49.4 5.1 0.8 33.3 5.5 1.8
25.2 56.7 5.2 1.3 35.4 1.0 2.8
23.5 57.0 4.9 1.0 36.1 0.7 1.3
23.1 55.2 5.3 1.3 37.2 0.6 1.5
26.5 54.4 5.0 1.2 38.3 0.7 1.9
23.4 54.2 5.4 1.4 38.0 0.6 1.3
13.2 44.9 5.6 1.5 47.9 0.0 0.0
20.0 53.6 4.9 0.5 40.9 0.0 0.7
20.0 51.2 5.6 1.4 40.9 0.4 10.5
A. Chatziapostolou et al. / International Journal of Coal Geology 65 (2006) 3–166
4. Results and discussion
Macroscopical description of the samples accord-
ing to the International Committee for Coal and Or-
ganic Petrology guidance (ICCP, 1993) showed that
the lignite belongs to the matrix lithotype.
4.1. Laboratory results
The ash yields (on dry basis) of the lignite samples
range between 13–72%, showing high inorganic in-
flux from the basin margins into the palaeomire (Table
1). The mean ash values for cores KP-13 and KP-7 are
30% and 43%, respectively. The contents of C (on dry,
ash-free basis) range between 44.9–60.3% (mean
value 56%), of H between 4.6–5.6% (mean value
5%), of N between 0.5–1.7% (mean value 1.1%)
and the contents of O between 30.2–47.9% (mean
value 34.5%) (Table 1). The content of S in bulk
samples is up to 5.5% (mean value 2.1%), and in
ashed samples up to 13.4% (mean value 4.5%)
(Table 1).
The mineralogical determinations on the ashes
revealed that quartz, K-feldspars, mixed-layer clays
Table 2
Semi-quantitative mineralogical composition of the Pellana lignite ashes (
Sample Quartz K-feldspars Illite/micas
KP-13/3 20.3 21.5 32.0
KP- 13/5 – – 19.8
KP-13/8 8.2 – 16.0
KP-13/11 11.7 – 15.8
KP-13/13 14.5 – 14.3
KP-13/16 16.4 – 16.1
KP-13/23 18.2 – 27.3
KP-13/27 12.3 – 22.9
KP-13/31 11.5 – 11.4
KP-13/43 12.8 16.9 18.9
KP-13/47 24.1 15.6 16.9
KP-13/51 – – 35.2
KP-13/59 13.4 13.9 20.5
KP-13/61 18.8 – 28.0
KP-7/3 22.6 – 23.3
KP-7/7 23.1 20.4 28.2
KP-7/8 29.0 25.4 27.3
KP-7/14 39.3 – 36.8
KP-7/18 26.3 21.9 36.2
KP-7/21 35.4 – 37.6
KP-7/22 40.7 – 44.7
KP-7/25 39.0 – 30.9
(illite-rich) and micas are the major mineral phases
contained in the Pellana lignite (Table 2). These
minerals correspond to primary phases. The identifi-
cation of anhydrite in ashes implies the presence of
gypsum, although neo-formation of anhydrite from
organically associated Ca+2 and SO4�2 cannot be
excluded (Vassilev and Vassileva, 1996; Ward et al.,
2001). Nevertheless, preliminary X-ray diffraction on
bulk samples revealed the occurrence of gypsum as a
primary phase. Oxides and hydroxides occur subordi-
nately and probably represent minerals that do not
correspond to primary phases. Semi-quantitative anal-
yses show that KP-13 core contains more anhydrite
and hematite than KP-7 core (Table 2).
4.2. Geochemical data
In the bulk samples of both cores the concentra-
tions of Al, Fe, Ca, Mg and K exceeds 1000 ppm.
Minor elements (100–1000 ppm) are Na, Mn and Ba,
while the concentrations of Be, Bi, Cd, Ce, Co, Cs,
Cu, Eu, Ga, Hf, La, Li, Lu, Mo, Nb, Nd, Pb, Rb, Sb,
Se, Sm, Sn, Sr, Tb, Te, Th, Tl, U, Y, Yb and Zr do not
exceed 100 ppm. The concentrations of many ele-
750 8C)
Anhydrite Hematite Brookite Lime
13.2 13.0 – –
70.1 10.1 – –
60.6 15.2 – –
62.4 10.1 – –
57.8 13.4 – –
56.6 10.9 – –
38.8 15.7 – –
51.3 13.5 – –
66.7 10.4 – –
40.1 11.3 – –
29.5 13.9 – –
64.8 – – –
41.2 11.0 – –
17.3 35.9 – –
39.8 14.3 – –
15.4 12.9 – –
18.3 – – –
23.9 – – –
15.6 – – –
– – 16.4 10.6
14.6 – – –
14.7 15.4 – –
A. Chatziapostolou et al. / International Journal of Coal Geology 65 (2006) 3–16 7
ments like As, Ba, Cr, Ni, V and Zn widely range
among the bulk samples. However, it should be noted
that the concentrations of the elements Cd, Hf, Lu and
Table 3
Element concentrations (in ppm, except otherwise cited) in the bulk-lignit
KP-13
3 5 8 11 13 16 23 27 31 43 47
Al%b 3.3 1.9 0.8 0.5 0.3 0.3 3.5 0.7 2.3 3.2
Fe%b 3.4 3.1 1.3 1.1 0.9 1.6 2.4 1.4 1.0 2.5 2.0
Ca%b 1.4 2.5 2.7 2.9 3.0 3.2 2.2 2.1 2.8 2.6 2.1
Mg%b 0.5 0.3 0.1 0.1 0.1 0.1 0.4 0.1 0.2 0.3 0.3
K%b 0.6 0.3 0.1 0.1 0.03 0.1 0.5 0.2 0.1 0.3 0.2
Na%b 0.03 0.03 0.02 0.02 0.02 0.02 0.03 0.02 0.02 0.03 0.0
As 137 168 60 27 25 28 16 13 9.8 94 70
Bab 133 50 89 90 80 103 78 84 95 77 15
Be 1.3 0.9 0.5 0.3 0.2 0.2 1.5 0.3 0.3 1.5 1.7
Bi 0.4 0.2 0.1 0.1 0.1 0.1 0.3 0.1 0.1 0.3 0.2
Cd 0.1 0.1 bdl bdl bdl bdl 0.2 bdl bdl 0.2 0.1
Ce 45 21 10 11 8.1 7 36 11 8.1 34 39
Co 14 6.2 2.3 4.4 3.3 2.6 9.9 3.1 1.7 12 11
Crb 29 29 16 8.2 8.1 8.0 42 17 12 20 33
Cs 2.9 1.8 0.7 0.4 0.2 0.3 2.7 1 0.6 2.6 2.2
Cu 50 24 9.5 8 5.4 6.0 37 17 8.8 35 22
Eu 0.8 0.4 0.2 0.2 0.2 0.1 0.7 0.2 0.1 0.6 0.7
Ga 8.4 5.3 2 1.3 0.8 0.9 9.7 2.7 2 6.1 9.3
Hf bdl 0.2 bdl bdl bdl bdl 0.3 bdl bdl 0.6 0.6
La 21 11 5.1 4.2 2.8 3.2 19 5.8 3.9 16 19
Li 28 16 5.4 2.2 0.6 1.4 22 6.9 3.4 15 23
Lu bdl bdl bdl bdl bdl bdl 0.1 bdl bdl bdl 0.2
Mnb 309 337 686 737 756 794 606 525 707 693 63
Mo 5.1 14 11 4.8 6.4 7.7 11 17 5.8 8.3 1.5
Nb 0.5 0.7 0.4 0.3 0.3 0.2 1.6 0.4 0.3 2.1 1.8
Nd 19 9.2 4.9 4.1 3.0 2.6 17 4.8 3.4 15 18
Ni 34 31 12 9.5 10 7.5 33 15 8.7 28 31
Pb 26 12 4.3 3.9 3.4 3.1 19 6.6 3.9 20 9.6
Rb 36 21 5.7 5.0 2.0 2.8 33 11 8.0 19 18
Sb 0.4 0.9 1.2 0.5 0.7 0.7 1.0 1.4 0.9 1.6 0.2
Se 1.9 3.4 3.2 2.4 2.7 2.6 3.5 3.1 2.8 1.5 1.4
Sm 3.8 1.9 1.1 0.9 0.7 0.5 3.5 1.0 0.6 2.9 3.7
Sn 0.4 0.2 bdl bdl bdl 0.1 0.4 bdl 0.1 0.3 0.4
Srb 50 68 61 68 67 73 61 50 65 67 68
Tb 0.4 0.2 0.1 0.1 0.1 bdl 0.4 0.1 bdl 0.4 0.5
Te 0.1 0.1 bdl bdl bdl bdl bdl bdl bdl bdl bd
Th 9.7 4.0 1.6 1.3 1.0 0.9 6.2 2.2 1.4 10 4.6
Tl 0.3 0.2 0.1 0.1 0.1 0.1 0.3 0.1 0.1 0.3 0.2
U 0.9 3.2 4.1 1 1.5 1.9 3.6 3.1 2.1 1.5 0.6
Vb 45 57 65 20 32 33 127 50 47 45 56
Y 8.2 4.8 3.5 2.9 2.9 1.9 10 2.5 1.7 10 13
Yb 0.7 0.4 0.2 0.2 0.3 0.1 1 0.2 0.1 0.7 1.1
Znb 68 43 27 17 4.8 5.6 39 27 11 47 22
Zrb 3.6 5.2 2.5 1.8 1.6 1.3 9 2.6 1.3 22 17
dl=detection limit.a Crustal average and worldwide coal concentrations after Clarke and Sb Elements determined using ICP-AES, the rest using ICP-MS.
Te in some lignite samples, and these of the Hf and
Nb in some ashed samples are below the detection
limit (Tables 3 4 5 and 6).
e samples of KP-13 core
51 59 61 Min Max Mean Cr.a Coalsa
0.8 2.3 4.6 0.3 4.6 1.8
0.9 2.0 5.3 0.9 5.3 2.1
2.2 1.9 1.3 1.3 3.2 2.4
0.1 0.2 0.3 0.1 0.5 0.2
0.1 0.5 0.6 0.03 0.6 0.4
2 0.02 0.04 0.04 0.02 0.04 0.02
32 88 177 9.8 177 67.3 1 0.5–80
6 94 38 16 16 156 84.5 425 20–1000
0.4 1.0 1.8 0.2 1.8 0.9 3 0.1–15
0.2 0.2 0.3 0.1 0.4 0.2 0.2
bdl bdl 0.4 0.1 0.4 0.2 0.2 0.1–3
14 19 40 7 45 21.6 60 2–70
7.5 8.9 16 1.7 16 7.4 25 0.5–30
9.8 24 58 8.0 58 22.5 100 0.5–60
0.8 2.1 3.9 0.2 3.9 1.6 3 0.3–5
9.9 20 39 5.4 50 20.8 55 0.5–50
0.2 0.5 0.8 0.1 0.8 0.4 1.2 0.1–2
2.1 6.4 13 0.8 13 5.0 15 1–20
bdl bdl 0.4 0.2 0.6 0.4 3 0.4–5
6.8 9.8 20 2.8 21 10.5 30 1–40
5 15 53 0.6 53 14.1 20 1–80
bdl 0.1 0.2 0.1 0.2 0.2 0.5 0.03–1
8 736 514 421 309 794 604 950 5–300
0.6 8.2 12 0.6 17 8.1 1.5 0.1–10
0.1 0.7 2.2 0.1 2.2 0.8 20 1–20
5.7 9.6 20 2.6 20 9.7 28 3–30
13 25 72 7.5 72 23.5 75 0.5–50
5.9 11 24 3.1 26 10.9 13 2–80
9.2 30 48 2.0 48 17.7 90 2–50
0.3 0.7 1.0 0.2 1.6 0.8 0.2 0.05–10
0.2 1.2 1.9 0.2 3.5 2.3 0.1 0.2–10
1.1 2.2 4.1 0.5 4.1 2.0 6 0.5–6
1.0 0.4 0.6 0.1 1.0 0.4 2 1–10
52 50 46 46 73 60.3 375 15–500
0.1 0.3 0.5 0.1 0.5 0.3 0.9 0.1–1
l bdl bdl bdl 0.1 0.1 0.1 0 b0.1
2.0 4.1 7.0 0.9 10 4.0 7.2 0.5–10
0.1 0.3 0.6 0.1 0.6 0.2 0.5 b1
0.2 1.5 2.1 0.2 4.1 2.0 1.8 0.5–10
16 53 161 16 161 57.6 135 2–100
2.7 9.1 13 1.7 13 6.1 33 2–50
0.2 0.8 1.4 0.1 1.4 0.5 3.4 0.3–3
34 26 98 4.8 98 33.5 70 5–300
0.5 3.2 14 0.5 22 6.1 165 5–200
loss (1992).
Table 4
Element concentrations (in ppm, except otherwise cited) in the bulk-lignite samples of KP-7 core
KP-7
3 7 8 14 18 21 22 25 Min Max Mean Cr.a Coalsa
Al%b 2.3 2.3 3.3 2.1 3.7 5.1 4.0 3.3 2.1 5.1 3.3
Fe%b 1.2 1.2 1.4 1.1 1.7 3.4 2.2 2.2 1.1 3.4 1.8
Ca%b 2.2 1.7 1.9 1.9 1.7 1.9 1.6 1.4 1.4 2.2 1.8
Mg%b 0.5 0.5 0.5 0.4 0.7 1.2 0.9 0.9 0.4 1.2 0.7
K%b 0.4 0.4 0.6 0.3 0.8 0.8 0.7 0.5 0.3 0.8 0.6
Na%b 0.02 0.02 0.03 0.02 0.03 0.02 0.02 0.01 0.01 0.03 0.02
As 5.6 3.2 5.5 7.8 10.3 5.2 7.5 12.2 3.2 12.2 7.2 1 0.5–80
Bab 134 154 189 158 222 209 198 172 134 222 180 425 20–1000
Be 0.9 0.7 1.0 0.8 1.2 1.6 1.6 1.5 0.7 1.6 1.2 3 0.1–15
Bi 0.2 0.2 0.2 0.2 0.2 0.4 0.3 0.3 0.1 0.4 0.2 0.2
Cd bdl bdl 0.2 0.1 0.1 0.2 0.2 0.1 0.1 0.2 0.2 0.2 0.1–3
Ce 12 11.9 22.7 17.1 19.6 34.1 20.3 21.6 11.9 34.1 20.0 60 2–70
Co 12.4 6.1 26.6 13.1 10.7 21.3 12.4 15 6.1 26.6 14.7 25 0.5–30
Crb 64.2 64.5 75.8 73 92.9 175 158 120 64.2 175 103 100 0.5–60
Cs 2.3 2.2 3.0 1.6 3.5 4.2 3.6 2.8 1.6 4.2 2.9 3 0.3–5
Cu 20.9 18.3 31.6 26.1 33.9 63.8 52.3 41.5 18.3 63.8 36.1 55 0.5–50
Eu 0.4 0.3 0.5 0.4 0.5 1.0 0.8 0.8 0.3 1.0 0.6 1.2 0.1–2
Ga 6.2 5.9 8.0 5.6 9.1 12.5 9.8 8.5 5.6 12.5 8.2 15 1–20
Hf 0.2 0.2 0.3 0.2 0.2 0.3 0.3 0.2 0.2 0.3 0.2 3 0.4–5
La 5.2 5.2 10 7.2 8.7 15.5 9.5 9.4 5.2 15.5 8.8 30 1–40
Li 20.3 21.6 31 21.9 34.4 63.1 45.3 42.8 20.3 63.1 35.1 20 1–80
Lu bdl bdl bdl bdl bdl 0.1 0.2 0.1 0.1 0.2 0.1 0.5 0.03–1
Mnb 311 260 274 244 259 310 269 256 244 311 273 950 5–300
Mo 1.4 0.5 1.5 1.4 1.2 0.9 0.9 0.8 0.5 1.5 1.1 1.5 0.1–10
Nb 0.8 0.7 1.2 1.1 1.0 1.1 1.0 0.7 0.7 1.2 1.0 20 1–20
Nd 6.8 6.7 11.6 9.3 10.3 20.3 13.1 14.1 6.7 20.3 11.5 28 3–30
Ni 111 67.9 140 96.2 112 220 154 162 67.9 220 133 75 0.5–50
Pb 5.8 5.9 11.4 8.1 7.3 17.6 13.5 11.3 5.8 17.6 10.1 13 2–80
Rb 28.7 30.9 44.1 22.1 51 51 46 37.4 22.1 51 38.9 90 2–50
Sb 0.2 0.1 0.3 0.3 0.3 0.3 0.4 0.3 0.1 0.4 0.3 0.2 0.05–10
Se 0.6 0.5 0.2 1.3 0.8 1.3 1.8 1.2 0.2 1.8 1.0 0.1 0.2–10
Sm 1.6 1.5 2.5 2.1 2.3 4.5 3.2 3.5 1.5 4.5 2.7 6 0.5–6
Sn 0.3 0.2 1.1 0.2 0.5 0.6 0.5 0.4 0.2 1.1 0.5 2 1–10
Srb 70.3 54.6 62.5 61.5 62 46.3 54.1 47.9 46.3 70.3 57.4 375 15–500
Tb 0.2 0.2 0.3 0.3 0.3 0.5 0.5 0.5 0.2 0.5 0.4 0.9 0.1–1
Te 0.04 0.02 0.1 0.02 0.1 0.1 0.1 0.1 0.02 0.1 0.1 0 b0.1
Th 2.3 2.3 2.9 2.7 2.8 5.8 3.9 3.7 2.3 5.8 3.3 7.2 0.5–10
Tl 0.2 0.2 0.3 0.2 0.3 0.3 0.3 0.2 0.2 0.3 0.2 0.5 b1
U 0.2 bdl 0.4 0.3 0.3 bdl 0.1 0.2 0.1 0.4 0.3 1.8 0.5–10
Vb 53 49 71 59 80 127 124 96 49 127 82.4 135 2–100
Y 5.6 5.0 6.7 6.1 8.1 13.5 16.2 14 5.0 16.2 9.4 33 2–50
Yb 0.4 0.4 0.5 0.5 0.5 1.0 1.3 1.1 0.4 1.3 0.7 3.4 0.3–3
Znb 34.3 33.6 152 59 50.1 94.6 71.5 69 33.6 152 70.5 70 5–300
Zrb 4.7 4.6 6.7 5.9 5.6 9.0 7.8 4.8 4.6 9.0 6.1 165 5–200
dl=detection limit.a Crustal average and worldwide coal concentrations after Clarke and Sloss (1992).b Elements determined using ICP-AES, the rest using ICP-MS.
A. Chatziapostolou et al. / International Journal of Coal Geology 65 (2006) 3–168
The average concentrations of most elements in the
lignite samples are within the range of world coal
(Swaine, 1990; Clarke and Sloss, 1992) and only
Mn for core KP-13 and Cr and Ni for core KP-7
show higher mean concentrations than world coal
(Tables 3 and 4). Element concentrations for the
Table 5
Element concentrations (in ppm, except otherwise cited) in the ashed samples of KP-13 core
KP-13
3 5 8 11 13 16 23 27 31 43 47 51 59 61 Min Max Mean
Al%a 5.1 4.9 5.2 3.7 2.9 3.1 6.8 6.8 5.0 7.4 8.4 6.9 4.0 6.9 2.9 8.4 5.5
Fe%a 5.6 10 7.3 7.6 8.1 11 5.7 8.4 7.8 9.0 5.1 6.9 6.4 10.3 5.1 11.0 7.8
Ca%a 2.2 7.2 12.6 12.8 18.4 13.5 5.6 11 14.2 8.6 5.0 16.3 7.7 2.8 2.2 18.4 9.8
Mg%a 1.0 1.0 0.8 0.9 1.1 0.9 1.0 1.0 1.2 1.0 0.9 1.1 0.7 0.8 0.7 1.2 1.0
K%a 1.5 0.8 0.5 0.7 0.3 0.7 1.0 1.2 1.0 0.9 0.6 1.0 0.6 0.9 0.3 1.5 0.8
Na%a 0.3 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.1 0.2 0.2 0.2 0.1 0.3 0.2
As 219 524 317 151 210 163 32.6 62.6 44.9 304 170 258 304 333 32.6 524 221
Baa 129 60.3 71.5 83.1 80.4 84.5 102 71.3 83.9 50.6 95.5 97.9 76.8 131 50.6 131 87.0
Be 2.2 2.1 1.4 1.7 1.7 1.1 2.7 2.0 1.5 3.7 3.6 2.3 1.5 3.0 1.1 3.7 2.2
Bi 0.5 0.6 0.3 0.2 0.1 0.1 0.5 0.5 0.3 0.8 0.3 0.2 0.6 0.7 0.1 0.8 0.4
Cd 0.2 0.5 0.2 0.1 0.1 bdl 0.5 0.3 0.2 0.4 0.4 0.1 0.3 0.9 0.1 0.9 0.3
Ce 54.5 61.0 55.8 53.2 57 35.3 77.2 55.8 41.8 91.2 103 79.1 51.3 98.5 35.3 103 65.3
Co 20.6 17.8 11.8 25.4 27.5 15.8 22.4 16.8 11.5 38.6 26.2 52.3 24.4 28.4 11.5 52.3 24.2
Cra 69.2 93.2 112 72.1 94.8 79.7 123 139 112 84.8 114 107 66.1 145 66.1 145 101
Cs 4.8 4.1 3.9 3.2 1.5 2.5 4.4 5.5 4.0 5.8 4.8 6.1 3.0 4.6 1.5 6.1 4.2
Cu 44.5 54.9 45.5 41.3 48.7 33.8 65.9 83.6 48.0 89.2 50.0 84.4 33.1 57.4 33.1 89.2 55.7
Eu 1.0 1.1 1.2 1.1 1.4 0.7 1.5 1.0 0.8 1.8 2.0 1.4 1.4 1.8 0.7 2.0 1.3
Ga 14.6 14.9 13.3 11.6 9.8 10.0 19.3 18.6 14.4 19.5 24.8 20.4 10.9 18.6 9.8 24.8 15.8
Hf bdl bdl 0.2 0.3 0.3 0.2 bdl 0.1 0.2 0.2 0.3 0.2 bdl 0.1 0.1 0.3 0.2
La 26.7 32.5 31.9 24.1 24.1 18.5 39.4 31.3 21.5 44.5 51.6 42.3 28.4 53.2 18.5 53.2 33.6
Li 55.9 48.3 32.3 15.4 12.0 11.3 45.0 39.3 19.3 42.7 45.6 35.0 42.3 94.0 11.3 94 38.5
Lu 0.1 0.2 0.2 0.2 0.4 0.1 0.3 0.1 0.1 0.3 0.4 0.2 0.4 0.4 0.12 0.4 0.24
Mna 439 941 3720 4210 6130 4680 1360 2650 4560 2240 1440 4980 1630 756 439 6130 2838
Mo 8.53 45.6 66.4 28.2 52.9 46.8 25.6 95.6 37.4 27.7 4.06 10.7 29.9 25.7 4.1 95.6 36
Nb bdl 0.1 0.2 0.2 0.4 0.3 bdl bdl 0.1 0.3 0.1 0.2 bdl bdl 0.1 0.4 0.2
Nd 23.1 26.7 26.4 22.9 24.5 14.6 34.2 25.6 17.5 40.4 47.5 35.2 26.7 42.8 14.6 47.5 29.1
Ni 57.2 82.5 75.0 63.2 96.4 53.1 81.3 91.7 63.4 97.7 78.4 100 76.6 140 53.1 140 82.6
Pb 44.7 37.0 24.7 25.7 22.7 15.7 48.7 38.2 24.0 63.3 25.7 38.7 37.3 47.1 15.7 63.3 35.3
Rb 93.1 68.1 45.7 49.7 23.4 43.3 73.8 91.4 68.5 70.2 51.1 96.0 48.8 81.6 23.4 96.0 64.6
Sb 1.3 2.9 4.5 1.7 3.0 2.2 1.3 4.6 2.6 2.7 0.5 1.0 1.5 1.6 0.5 4.6 2.2
Se 1.7 1.1 2.4 4.0 16.5 4.9 2.2 2.8 4.4 1.1 0.3 3.3 0.3 0.3 0.3 16.5 3.2
Sm 4.7 5.2 5.4 4.9 6.1 3.0 7.0 5.0 3.5 8.3 9.3 6.6 6.0 8.2 2.96 9.3 5.9
Sn 0.6 0.8 0.8 0.6 0.4 0.6 0.7 0.9 0.7 0.9 1.1 1.2 0.5 0.8 0.4 1.2 0.8
Sra 93.6 215 329 363 425 363 168 292 369 239 193 436 195 114 93.6 436 271
Tb 0.6 0.6 0.7 0.7 1.0 0.4 0.9 0.5 0.4 1.1 1.1 0.7 1.1 1.0 0.4 1.1 0.8
Te 0.1 0.1 0.0 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.0 0.1 0.1
Th 10.9 11.4 9.8 8.5 9.4 6.0 14.3 12.0 8.8 33.4 12.7 14.3 13.1 15.5 6.0 33.4 12.9
Tl 0.7 0.9 0.7 0.1 bdl 0.2 0.8 0.9 0.4 0.9 0.7 0.5 0.6 1.1 0.1 1.1 0.7
U 10.8 73.3 176 45.9 91.5 83.1 66.8 132 110 38.4 10.3 13.0 43.4 31.6 10.3 176 66.2
Va 78 172 387 144 316 230 272 302 295 136 135 121 124 285 77.7 387 214
Y 13.1 16.3 22.1 20.0 29.5 13.0 25.9 14.7 11.6 37.0 30.6 20.8 35.8 28.4 11.6 37.0 22.8
Yb 1.0 1.2 1.3 1.7 2.7 0.9 2.2 1.1 0.9 2.3 2.5 1.3 2.8 2.5 0.9 2.8 1.7
Zna 104 104 56.7 70.6 54.8 36.6 86.1 132 52.5 92.3 55 181 70.7 165 36.6 181 90
Zra 1.5 5.8 9.0 10.7 14.3 9.7 5.9 7.1 8.7 22.4 17.1 11.4 4.7 7.8 1.5 22 9.7
dl=detection limit.a Elements determined using ICP-AES, the rest using ICP-MS.
A. Chatziapostolou et al. / International Journal of Coal Geology 65 (2006) 3–16 9
ashed samples presented in Tables 5 and 6, are com-
pared to those reported for several lignite-bearing
basins in Greece (Foscolos et al., 1989, 1998; Filippi-
dis et al., 1996; Gentzis et al., 1996, 1997; Iordanidis
et al., 2001; Pentari et al., 2004). The average con-
centrations for all elements in the ashed samples, are
within the range of the Greek coal, except Nb which is
lower (Tables 5 and 6). Moreover, the average con-
Table 6
Element concentrations (in ppm, except otherwise cited) in the ashed samples of KP-7 core
KP-7
3 7 8 14 18 21 22 25 Min Max Mean
Al%a 7.9 8.2 7.4 8.2 8.7 6.8 8.1 7.8 6.8 8.7 7.9
Fe%a 5.4 4.7 4.3 4.5 4.9 4.4 4.4 4.8 4.3 5.4 4.7
Ca%a 9.5 6.7 5.3 6.2 5.3 2.5 3.1 3.0 2.5 9.5 5.2
Mg%a 1.9 1.9 1.6 1.8 2.0 1.8 1.9 2.0 1.6 2.0 1.9
K%a 1.2 1.3 1.3 1.3 1.5 1.2 1.5 1.5 1.2 1.5 1.4
Na%a 0.2 0.2 0.1 0.2 0.2 0.1 0.1 0.2 0.1 0.2 0.2
As 19.9 11.0 20.9 24.0 21.5 6.3 13.8 25.9 6.29 25.9 17.9
Baa 137 230 196 135 207 321 397 422 135 422 256
Be 2.5 2.2 2.2 2.7 2.5 2.2 3.1 3.1 2.2 3.1 2.6
Bi 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5
Cd 0.2 0.2 0.5 0.5 0.3 0.3 0.4 0.3 0.2 0.5 0.3
Ce 65.2 68.0 78.3 80.5 74.5 72.3 65.0 71.0 65.0 80.5 71.9
Co 48.2 21.9 73.3 44.8 30.4 26.3 24.1 30.7 21.9 73.3 37.5
Cra 320 311 260 358 320 303 402 356 260 402 329
Cs 7.1 7.4 7.3 8.1 8.3 7.2 8.1 8.1 7.12 8.29 7.69
Cu 67.4 52.4 69.1 76.3 75.2 57.0 73.0 64.8 52.4 76.3 66.9
Eu 1.5 1.4 1.6 1.7 1.6 1.5 1.7 1.8 1.4 1.8 1.6
Ga 22.0 22.3 20.7 25.1 22.8 18.4 21.1 20.7 18.4 25.1 21.6
Hf 0.2 bdl bdl bdl bdl bdl bdl bdl 0.2 0.2 0.2
La 33.8 35.6 40.5 41.2 39.9 40.1 37.5 39.1 33.8 41.2 38.4
Li 63.3 64.9 65.3 66.8 73.2 65.9 71.0 72.2 63.3 73.2 67.8
Lu 0.2 0.2 0.2 0.2 0.2 0.2 0.3 0.3 0.2 0.3 0.2
Mna 1240 994 764 854 750 373 520 525 373 1240 752
Mo 5.5 2.0 4.7 4.4 3.2 1.1 1.6 1.6 1.1 5.5 3.0
Nb 0.2 bdl bdl bdl bdl bdl bdl bdl 0.2 0.2 0.2
Nd 29.3 30.0 36.4 36.1 35.3 32.9 30.5 34.7 29.3 36.4 33.2
Ni 450 264 402 357 348 288 322 355 264 450 348
Pb 22.9 24.2 33.7 29.5 23.7 24.0 28.1 22.5 22.5 33.7 26.1
Rb 103 116 119 111 130 97.2 117 113 97 130 113
Sb 0.3 0.2 0.4 0.4 0.2 0.2 0.3 0.2 0.2 0.4 0.3
Se 1.9 1.0 1.3 0.1 1.5 bdl bdl bdl 0.1 1.9 1.2
Sm 6.4 6.2 7.2 7.4 7.3 6.5 6.5 7.6 6.2 7.6 6.9
Sn 1.0 0.9 0.8 0.9 0.9 0.6 0.8 0.8 0.6 1.0 0.8
Sra 322 244 211 247 218 81.4 131 126 81 322 198
Tb 0.8 0.8 0.9 0.9 0.9 0.8 1.1 1.1 0.8 1.1 0.9
Te 0.1 0.1 0.4 0.1 0.1 0.1 0.1 0.2 0.1 0.4 0.2
Th 8.8 8.9 8.9 9.1 8.4 7.0 8.2 8.0 7.0 9.1 8.4
Tl 0.8 0.9 1.2 1.0 0.8 0.7 0.8 0.7 0.7 1.2 0.9
U 5.8 2.6 8.5 7.3 6.8 1.1 1.8 2.9 1.1 8.5 4.6
Va 185 170 170 213 163 151 213 209 151 213 184
Y 23.9 21.0 20.3 24.2 27.0 19.2 34.2 32.8 19.2 34.2 25.3
Yb 2.0 1.0 1.0 2.0 2.0 1.0 3.0 2.0 1.0 3.0 2.0
Zna 116 117 335 178 141 126 133 133 116 335 160
Zra 8.8 5.2 4.9 5.9 3.1 0.9 1.8 1.5 0.9 8.8 4.0
dl=detection limit.a Elements determined using ICP-AES, the rest using ICP-MS.
A. Chatziapostolou et al. / International Journal of Coal Geology 65 (2006) 3–1610
centrations of the elements U and As in the Pellana
lignite ashes of core KP-7 show similar values to the
Megalopolis lignite ashes (Sakorafa et al., 1996),
whereas the concentrations of U and As in core KP-
13 are much higher (Tables 5 and 6). The elements Cs,
Cu, Hf, Lu and Zr show lower values in comparison to
A. Chatziapostolou et al. / International Journal of Coal Geology 65 (2006) 3–16 11
the Megalopolis lignite ashes, while Mn shows higher
concentration values in the Pellana lignite ashes from
both cores (Tables 5 and 6). The Mn enrichment of the
Pellana lignite is attributed to leaching from the Mn-
rich limestones (Pindos geotectonic zone), which con-
sist part of the margins of the Pellana basin (Pe-Piper
and Piper, 1989). On the contrary, the margins of the
Megalopolis basin consist mainly of flysch sediments
of the Pindos zone. Ophiolitic lenses occur inside
these sediments, which are enriched in hydrothermal
Cu, Zr and REE (Robertson and Varnavas, 1993;
Bizimis et al., 2000). It seems therefore, that the
different geochemical features of the marginal areas
have influenced the elemental composition of lignites
hosted in these basins. It is noticed, however, that the
geochemical mapping of the marginal areas of both
Megalopolis and Pellana basins is not detailed, and
hence only interpretations can be made.
4.3. Factor analysis
In order to assess the organic/inorganic affiliation
of the studied elements, R-type factor analysis was
applied on bulk-lignite concentrations re-calculated
on ash basis. The lignite concentrations were calcu-
lated on organic-free basis, in order to reduce the
influence from ash content variations. It has been
shown (Kalaitzidis and Christanis, 2002) that this
re-calculative approach of elemental concentrations
discloses relationships among elements that are not
evident from the statistical evaluation of the bulk-
data matrix. A 3-factor model with total cumulative
variance 70.9% was obtained. The elements Al, Be,
Bi, Cd, Ce, Cr, Cs, Cu, Eu, Ga, Hf, K, La, Li, Mg,
Nb, Nd, Ni, Pb, Rb Sm, Tb, Te, Th, Tl, Y and Yb
show strong correlation with the ash yield (on dry
Table 7
Results of R-mode factor analysis on the elementary data of the bulk l
mineralogical data of the ashed samples
Groups of R-mode factor analysis on bulk lignite data Gro
G1 Al, Cd, Cr, Cs, Cu, Ga, K, Li, Mg, Ni, Rb, Te — ash yield G1
As, Ba, C, Ca, Fe, Mn, Mo, Na, Stotal, Sb, Se, Sr, U
G2 Al, Be, Bi, Cd, Ce, Cs, Cu, Eu, Ga, Hf, La, Nb, Nd, Pb, Sm,
Tb, Th, Tl, Y, Yb
G2
Ba
G3 Fe, Mo, Stotal, Sb, Se, U, V G3
Ba, Co, Mg, Ni, Sn
basis); this grouping represents an inorganic affilia-
tion and probably these elements are incorporated
into the chemical structure of aluminosilicates
(Swaine, 1990; Querol et al., 1995a, b; Spears and
Zheng, 1999; Karayigit et al., 2000) (Table 7). On
the other hand, the strong correlation between As,
Ba, C, Ca, Fe, Mn, Mo, Na, Stotal, Sb, Se, Sr, U and
V represents an intermediate affiliation (organic–in-
organic) for these elements (Table 7).
Factor analysis was also applied in the element
concentrations of the lignite ashes in correlation
with the ash yield and the semi-quantitative analysis
of the mineral phases. R-type analysis proposes a 3-
factor model with total cumulative variance 68.5%.
Aluminum, Ba, Be, Bi, Cd, Ce, Co, Cr, Cs, Cu, Eu,
Ga, K, La, Li, Lu, Mg, Nd, Ni, Rb, Sm, Sn, Tb, Te,
Th, Tl, Y, Yb and Zn are associated with quartz, illite–
micas and the ash yield, while As, Fe, Mo, Na, Pb, Sb,
Th and U are associated with anhydrite and hematite.
Additionally, Ca, Hf, Mn, Nb, Sash, Se and Sr are
correlated with anhydrite (Table 7).
4.4. Trace element enrichment in the ash
In order to approach the mobility of the studied
elements, the relative enrichment factor (RE) was cal-
culated using the formula introduced by Meij (1995).
The most depleted — therefore, the most volatile
during ashing — trace elements (REmeanb0.5), are
Hf, Nb and Sb in core KP-7 samples and Nb in core
KP-13 samples. The elements Ba and Se are moder-
ately depleted in the ashed samples of core KP-7
(0.5bREmeanb0.7), while Ba, Bi, Se and Hf show
similar depletion in the ashed samples of core KP-13
(Table 8). Moreover, the observed obliqueness on the
RE values of U (REmean=8.3) shows that the deter-
ignite samples (on organic-free basis) and on the elementary and
ups of R-mode factor analysis on lignite ash data
Al, Ba, Co, Cr, Cs, Ga, K, Mg, Ni, Rb, Te, Zn — quartz,
illite/micas
As, Fe, Mo, Na, Pb, Sb, Th, U — anhydrite, hematite
Bi, Cd, K, Li, Rb, Tl — ash yield, illite/micas
Ca, Hf, Mn, Nb, Sash, Se, Sr — anhydrite
Al, Be, Cd, Ce, Cu, Eu, Ga, La, Lu, Nd, Sm, Sn, Tb, Th, Y, Yb
Table 8
Relative enrichment factors in the ash samples (according to Meij,
1995)
KP-13 KP-7
Range Mean Range Mean
Al 0.5–1.8a 1.1 0.9–1.3 1.1
Fe 0.9–1.5a 1.1 0.9–1.4a 1.1
Ca 0.8–1.3 1.0 0.9–1.4a 1.1
Mg 0.9–1.6a 1.3 1.1–1.5a 1.2
K 0.4–2.7a 1.3 0.8–1.4a 1.1
Na 1.3–6.2a 2.4 1.8–6.2a 3.7
As 0.8–1.5a 1.0 0.8–1.4a 1.0
Ba 0.1–4.2a 0.6 0.3–1.3 0.7
Be 0.5–1.3 0.9 0.8–1.1 0.9
Bi 0.2–1.1 0.6 0.8–1.2 0.9
Cd 0.6–1.7a 1.1 0.9–1.5a 1.2
Ce 0.8–1.3 1.0 1.3–2.0a 1.6
Co 0.8–1.3 1.0 0.9–1.3 1.1
Cr 0.8–2.0a 1.4 1.3–1.7a 1.4
Cs 0.4–1.6a 1.0 0.9–1.5a 1.2
Cu 0.5–1.6a 0.9 0.6–1.0 0.8
Eu 0.8–1.3 1.1 1.1–1.6a 1.2
Ga 0.5–2.0a 1.2 1.0–1.4a 1.1
Hf 0.1–0.2 0.8 0.3–0.3 0.3
La 0.8–1.3 1.0 1.5–2.4a 1.9
Li 0.8–2.7a 1.2 0.8–1.0 0.9
Lu 0.8–1.2 1.0 0.9–1.4a 1.1
Mn 0.9–1.2 1.3 0.9–1.3 1.1
Mo 0.9–3.5a 1.3 0.9–1.3 1.1
Nb 0.1–0.3 0.2 0.1–0.1 0.1
Nd 0.8–1.2 1.0 1.2–1.6a 1.3
Ni 0.9–1.5a 1.1 0.9–1.4a 1.1
Pb 0.9–1.2 1.1 1.0–1.4a 1.1
Rb 0.5–2.9a 1.5 1.0–1.5a 1.3
Sb 0.5–2.2a 0.8 0.3–0.7 0.4
Se 0.1–3.1a 0.5 0.7–2.5a 0.6
Sm 0.8–1.2 1.0 1.0–1.4a 1.1
Sn 0.2–1.7a 0.9 0.3–1.3 0.9
Sr 0.9–1.6a 1.1 1.2–1.6a 1.3
Tb 0.8–1.4a 1.1 0.9–1.4a 1.2
Te 0.4–1.0 0.9 0.7–2.2a 1.2
Th 0.8–1.3 1.1 0.9–1.3 1.1
Tl 0.3–1.7a 1.0 1.1–1.9a 1.5
U 7.3–11.9a 8.3 7.5–9.2a 6.4
V 0.7–1.4a 1.1 0.8–1.2 1.0
Y 1.0–1.4a 1.2 1.0–1.5a 1.2
Yb 0.9–1.7a 1.1 1.0–1.3 1.1
Zn 0.4–1.6a 0.9 0.8–1.2 1.0
a Significant divergence of RE from 1.0, probably due to the
heterogeneity of some lignite samples.
A. Chatziapostolou et al. / International Journal of Coal Geology 65 (2006) 3–1612
mined concentrations in either the lignite or the ashed
samples were not accurate, either due to the lack of
absolute homogeneity or due to incomplete digestion
and transfer to solution. Additionally, although the
elements Cd, Cs, Cu, Ga, Rb, Sn, Te, Tl and Zn
show REmean close to 1.0, their concentrations in
some samples have been significantly depleted during
combustion.
4.5. Mode of occurrence and potential mobility of
trace elements
The assessment of trace element affinity in the
Pellana lignite and the 750 8C ash is based on the
results of factor analysis. Most of the elements are
associated with the aluminosilicate minerals such as
mixed-layer clays, micas and feldspars (Table 9) that
represent the detrital inorganic input in the palaeo-
mire. The elements As, Ba, Mn, Mo, Na, Sb, Sr, U
and V show an intermediate affinity; from the
obtained data it can be inferred that this group of
elements is associated with the organic matter and/or
with the authigenic mineral phases of sulphates (gyp-
sum) and Fe-sulphides (pyrite). This is possibly due to
the fact that authigenic sedimentation of pyrite (FeS2),
and, to some extent of sulphates (SO4�2), in the
palaeomire was proportional to the accumulation of
organic matter; hence statistical tools cannot discrim-
inate between elements that are exclusively correlated
to organic carbon and those that are correlated to Fe
and Stotal. Arsenic, Mo, Sb, Se, U and Vare associated
with pyrite at high confidence level, as has been also
reported for other coals (e.g., Querol et al., 1995a;
Mukhopadhyay et al., 1998; Spears and Zheng, 1999),
although it cannot be excluded that part of these
elements may have an organic affinity. Intermediate
affinity is also revealed for Ba, part of which is
associated with the organic matter and part with the
sulphates (gypsum and barite) as also reported by
Querol et al. (1995a). However, the correlation of
Ba with the elements Co, Mg, Ni and Sn, which are
associated with clays and feldspars, indicates that the
latter minerals are the source of Ba that has been taken
up from the peat-forming plants. Intermediate affinity
is also revealed for Ca, Mn, Na and Sr; part of these
elements is associated with organic matter, which is
reasonable as these elements are useful nutrients for
plant growth, and part with sulphates (gypsum) and
carbonates.
An interesting aspect of the factor analysis is that
Hf, Nb, Pb and Th changed grouping-mode after
ashing; in bulk samples an affinity to aluminosilicates
Table 9
Mode of occurrence of trace elements in the Pellana lignite
Elements Mode of occurrence
Be, Bi, Cd, Ce, Co, Cr, Cs, Cu, Eu, Ga, Hf, La, Li, Lu, Nb, Nd,
Ni, Pb, Rb, Sm, Sn, Tb, Te, Th, Tl, Y, Yb, Zn
Aluminosilicate minerals (quartz, K-feldspars, mixed-layer clays)
Ba Intermediate (organic - aluminosilicates and gypsum)
As, Mo, Sb, Se, U, V Intermediate (organic - pyrite)
Mn, Sr Intermediate (organic - gypsum and carbonates)
A. Chatziapostolou et al. / International Journal of Coal Geology 65 (2006) 3–16 13
was evident, whereas after ashing an affinity to anhy-
drite and/or hematite (combustion products of gypsum
and pyrite, respectively) is revealed.
If the statistical interpretations were used to eval-
uate the mobility/volatilization mode of the trace ele-
ments during ashing, increasing potential mobility
would be assumed for the organic-associated elements
As, Ba, Mn, Mo, Sb, Se, Sr and U, as well as for Pb,
Th, Hf and Nb that changed affinity after ashing.
However, the relative enrichment factors reveal sig-
nificant to moderate depletion mode during ashing for
Ba, Bi, Hf, Nb, Sb, and Se, as well as for Cd, Cs, Cu,
Ga, Rb, Sn, Te, Tl and Zn in some samples. It is
obvious that for Ba, Hf, Nb, Sb and Se statistical
interpretation succeeded to provide the mobility ten-
dency. Regarding As, Mn, Mo, Pb, Sr, Th, and U, it
appears that these elements are associated with anhy-
drite and/or hematite during ashing (at 750 8C), andthus the respective relative enrichments are close to
1.0. The depletion of Cd, Cs, Cu, Ga, Rb, Sn, Te, Tl
and Zn is probably related to the thermal breakdown
of mixed-layer clays.
4.6. Environmental impacts
Many of the environmental and health problems
attributed to coal combustion are due to mobiliza-
tion of potentially toxic elements (Swaine and
Goodarzi, 1995). Emphasis is given to the elements
As, Cd, Mo, Pb and Se that are among the most
hazardous air pollutants (HAP); these elements may
be either volatilized during combustion or leached
from fly ash-disposal areas into underground waters.
Arsenic is responsible for carcinogenesis (Clarke
and Sloss, 1992; Swaine, 1995); Zheng et al.
(1996) and Finkelman et al. (2002) have also
shown that people who dried their crops directly
over coal fire suffered from chronic arsenic poison-
ing. Cadmium accumulates in the human body with
age, especially in the kidneys and liver, and is
carcinogenic (WEC, 1989); it is suspected that Cd
may bioaccumulate through the food chain (Clarke
and Sloss, 1992). Under some conditions Mo can
cause molybdenosis in animals that are fed with
vegetation containing relatively high concentrations
of Mo. Direct deposition of Pb from air results in
greater uptake of Pb by plants than it occurs
through the soil (WEC, 1989); lead in some com-
pounds may cause carcinogenesis in animals and
possibly in humans (US DOE, 1989). Nevertheless,
in case of Pellana lignite combustion, the volatiliza-
tion of As, Cd, Mo and Pb will be restricted as it is
inferred from the relative enrichment factors. How-
ever, we should expect environmental problems as-
sociated with the leaching ability of these elements
in post-combustion waste products.
On the other hand, environmental problems can
arise from the volatilization tendency of Se (low
relative enrichment factor and intermediate affinity)
in case of Pellana lignite mining and combustion.
Selenium can cause severe toxicity in plants and
animals. Human selenosis is attributed to the practice
of using combustion ash as a soil amendment. Symp-
toms of selenium poisoning include hair and nail loss
(Zheng et al., 1992; Finkelman et al., 2002).
The relative enrichment factors show that apart of
Se, the elements Hf, Nb, Sb, Ba and Bi are also
mobile, and pose a significant environmental risk.
Antimony represents a human health risk, if dust is
inhaled (Flynn et al., 2003). Baritosis was observed in
workers exposed to airborne barite dust or Ba-sul-
phate and also hypertension was observed in humans
(Malina, 2004). Both human and laboratory animal
investigations have shown hepatic, renal and neuro-
toxicity following Bi exposure (Jayasinghe et al.,
2004). Thus, measures should be applied in order to
retain these elements in the solid residuals. There are
no extensive studies about the hazardous impacts of
A. Chatziapostolou et al. / International Journal of Coal Geology 65 (2006) 3–1614
Hf and Nb to the environment and the human health,
caused by coal combustion.
In case of using Pellana lignite as feedstock to the
nearby Megalopolis Power Station more studies
should be conducted in order to assess the environ-
mental risk. The Station uses the pulverized coal
combustion technology, which requires a drying and
pulverization process before combustion. The pulver-
ization takes place in beater wheel mills. Partially
Indirect Firing is used for drying; i.e., electrostatic
precipitators are used for separating the mixture of
flue gas, air and water vapor from the pulverized
lignite. In order to reduce the SO2 emissions, the
Megalopolis Power Plant is fitted with a wet flue-
gas desulphurization system (Koukouzas et al., 2004).
The electrostatic precipitators in the lignite-fired
power plant of Megalopolis have recently been
upgraded in order to control the particulate emissions.
Heavy metals deposition (Cr, Pb, Ni, Cu and Mn) and
radioactivity in the surrounding area were examined
with no evidence of harmful environmental or health
effects due to low emission levels (Koukouzas et al.,
2004). Therefore, in case of using Pellana lignite as
feedstock to Megalopolis Power Station, we should
not expect environmental or health problems at least
for the elements, which reveal similar or lower con-
centrations than the Megalopolis lignite. Nevertheless,
due to the enriched mode of Mn in the Pellana lignite,
pilot studies are required. Measures such as the use of
various sorbents, should be applied for the retention of
As and Se. The metal oxide mixture sorbents can
retain As together with selenium and sulphur
(Somoano et al., 2004). Activated carbon can be
also used, which appears to be the better sorbent for
Se at a temperature range of 300–600 8C (Lachas et
al., 2003). Also the optimum combination for high As
retention and low leachability was found with kaolin
sorbent at 600 8C (Lachas et al., 2003). The possibility
of sorbent application for the retention of Se and As
during hot gas desulphurization, should be examined
for the Megalopolis Power Station, in case of Pellana
lignite combustion.
5. Conclusions
The ash yields (on dry basis) of the Pellana lignite
range between 13–72% and the contents of C (on dry,
ash-free basis) range between 44.9–60.3%. The S
content in lignite samples is up to 5.5% and in
ashed samples up to 13.4%. The mineral phases
contained in the Pellana lignite are quartz, K-feld-
spars, gypsum, pyrite, mixed-layer clays (illite-rich)
and micas.
Factor analysis on geochemical data reveals that
the elements As, Ba, Mn, Mo, Sb, Se, Sr, U and V
have an intermediate affiliation. These elements seem
to be organically associated and also have strong
correlation to gypsum, carbonates and/or pyrite.
Due to their organic affinity it is possible that these
elements will volatize during lignite combustion.
However, during heating at 750 8C, a significant
portion of these elements is still associated with
anhydrite and/or hematite. The relative enrichment
factor calculations show that the most depleted and
hence, mobile trace elements, of the Pellana lignites
in the event of their utilization for power generation,
are Hf, Nb and Sb, while Se, Ba and Bi are moder-
ately depleted. In case of the Pellana lignite utiliza-
tion, the elements Ba, Bi, Hf, Nb, Sb and Se may be
either volatilized during combustion or leached from
flyash-disposal areas into underground waters, caus-
ing severe environmental and health impacts. Minor
problems may arise from the leaching ability of the
elements As, Cd, Mo and Pb in post-combustion
waste products.
Acknowledgements
The authors would like to thank Mr. Dimitrios
Vachliotis, Laboratory of Instrumental Analysis, Fac-
ulty of Earth Sciences, University of Patras, for
performing the ultimate analysis. Dr. Eric Hoffman,
Activation Laboratories Ltd., Ancaster, Canada, is
gratefully thanked for performing the geochemical
analyses. Adamantia Chatziapostolou also thanks the
National Grant Foundation of Greece for support of
her study.
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