Mode of occurrence of trace elements in the Pellana lignite (SE Peloponnese, Greece

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


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 – –


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.


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.


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.


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


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.


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)


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


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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