an assessment of soil contamination due to heavy metals around a coal-fired thermal power plant in...

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Environmental Geology

International Journal of Geosciences

© Springer-Verlag 200610.1007/s00254-006-0336-8

Original Article

An assessment of soil contamination due to

heavy metals around a coal-fired thermal

power plant in India

A. Mandal 1 and D. Sengupta 2

Planetary and Geosciences Division, Physical Research Laboratory, Navrangpura, Ahmedabad, 380009,India

Department of Geology and Geophysics, IIT Kharagpur, Kharagpur, 721302, India

A. MandalEmail: [email protected]

D. Sengupta (Corresponding author)Email: [email protected]

Received: 2 April 2006

Accepted: 4 May 2006

Published online: 26 July 2006

Abstract

Combustion of coals in thermal power plants is one of the major sources of

environmental pollution due to generation of huge amounts of ashes, which

are disposed off in large ponds in the vicinity of the thermal power plants. This

problem is of particular significance in India, which utilizes coals of very high

ash content (∼55 wt%). Since the thermal power plants and the ash ponds are

located in densely populated areas, there is potential chance for

contamination of soil and groundwater of the surrounding areas from the toxic

trace elements in the ash. An attempt has been made to study the extent of

soil contamination around one of the largest thermal power plants of India

located at Kolaghat, West Bengal India. Chemical analysis of the top soils andFirefox can't load web fonts from a remote host

An assessment of soil contamination due to heavy metals... http://link.springer.com/article/10.1007/s00254-006-0336...

1 of 29 Tuesday 17 February 2015 07:53 PM

the soils collected from the different depth profiles surrounding the ash ponds,

show that the top soils are enriched in the trace elements Mo, As, Cr, Mn, Cu,

Ni, Co, Pb, Be, V, Zn, which show maximum enrichment (2–5) in the top soils

collected from all the soil profiles. These elements are also enriched in the

pond ash. Since there are no other sources of industrial effluents, it can be

said that the enrichment of the trace elements (Mn, Co, Mo, Cr, Cu, Pb, Zn, As,

Ni, Be, V) is attributed to their input from ash from the disposal pond. The

study has been further strengthened by log-normal distribution pattern of the

elements.

Keywords Fly ash – Bottom ash – Trace elements – Enrichment factor –Log-normal distribution

Introduction

The global energy needs have enormously increased with rapid strides in

technology and, these have been met, to a large extent from fossil fuels.

Coal-fired power plants generate about 23% of the electricity consumed

worldwide (EIA 2002). One of the major environmental problems associated

with the use of coal as fuel in thermal power plants is the production of ash.

This problem is particularly important for Indian power stations because most

of the power stations use poor quality coal with 5–50% ash yielding about

100 million tons of ash per annum (Vijayan and Behera 1999). The solid wastes

produced from the coal-fired thermal power plants are mainly of two types, i.e.

fly ash and bottom ash. Bottom ash is the coarse-grained fraction that is

collected from the bottom of the boiler and is disposed of by the wet disposal

method in a slurry form to nearby waste disposal sites (ash ponds). Fly ash

consists of finer sized particles, ranging from 0.5 to 200 μm (Baba 2002).

Owing to its relatively small size and, hence, large surface area, the ashes

have a greater tendency to absorb trace elements that are transferred from

coal to waste products during combustion (Gulec et al. 2001). Migration of the

trace elements from waste disposal sites to surrounding ecosystems is a

complex process. Trace elements present on the surface of ash particles are

readily leached (Shi and Sengupta 1995; Fytianos et al. 1998) and tend to

contaminate the groundwater (Theis and Gardner 1990; Theis et al. 1978;

Carlson and Adriano 1993).Firefox can't load web fonts from a remote host



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Soil is a mixture of natural bodies on the earth surface containing living

matter and supporting plants (Russal 1957). Soil is complex substance

because of its variation in physical and chemical composition. It contains small

significant quantities of organic and inorganic compounds, which are essential

for the growth of plants.

Soil contamination by heavy metals from waste disposal sites is a serious

problem in industrial and urban areas. Soil is the ultimate and most important

sink of trace elements in the terrestrial environment. Heavy metals are mainly

introduced to the environment through anthropogenic activities such as those

related to metal mining, metallurgical processing and waste disposal. Metal

contamination of surface soils (Pichtel et al. 1997), agricultural soils (Kim and

Kim 1998; Sharma et al. 2000), from industries (Ullrich et al. 1999; Bityukova

et al. 2000; Sterckeman et al. 2000) and waste disposal sites (Yarlagadda et al.

1995) is well known. Soil contamination around coal ash disposal sites takes

place in two different ways: through atmospheric fallout and due to leaching.

The topsoil (0–15 cm from the surface) is mainly affected by the ash fallout.

Atmospheric deposition from industrial activities can induce long-term

changes in soil quality (Jones 1991). Bertine and Goldberg (1971) have shown

that fossil fuel combustion can be a potentially significant source of

atmospheric discharge of many metals. Heavy metals from fossil fuel

combustion are a common source of pollution for surface soils (Parekh and

Husain 1987; Ramachandran et al. 1990). The inhomogeneties in the soil

composition may exert significant influences on individual and distribution

characteristics (Kim and Kim 1998). Contamination of surrounding soil due to

the deposition of air-borne ash plume from the disposal pond (Satyanarayana

Raju 1993; Praharaj et al. 2001) has been a matter of great concern.

Continuous input of ash into the soil has the potential to affect the

physicochemical characteristics of the soil (Carlson and Adriano 1993; Bilski

et al. 1995). Most trace elements act as micro-nutrients to certain plants but

become toxic at enhanced levels in the soil, thereby contaminating the land

(Mukherjee and Nag 1997). Coal ash contains high concentration of trace

elements, which affect the soil properties and vegetation grown around the

ash disposal site. Studies by Bityukova et al. 2000 on the pollution of soil

around industries have shown that the levels of As, Cr, Mn and V were more

than three times higher and levels of Pb and Zn were more than five times

higher than the background levels.

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Coal combustion from thermal power plants contributes to 86% of the total

electricity generation in Eastern India as compared to the other parts of India.

The Kolaghat thermal power plant, in West Bengal, in Eastern India is the

second largest, next to Farakka. Nearly 14,000 tonnes of coal are burnt to run

the six units of the Kolaghat Thermal Power Plant, emitting 5,000 tonnes of

ash. But there are only four ash ponds, covering an area of 253 acres, which

do not have the capacity to accommodated such huge quantities of ash.

Kolaghat officials feel that at least 1,253 acres of land are required for

depositing the ash. The ash is deposited both by the dry and wet disposal

methods. In the dry method, the ash is transported in trucks and dumped in

open ponds located 3 km S, SW and NW of the power plant, near the villages

of Rakshachak, Bahala and Mecheda. Absence of covering of the ash pile in

the trucks causes it to fly in the prevalent wind direction. Apart from this the

ash is also mixed with water to form slurry and then transported through

pipes to disposal ponds, where upon disposal it gets dried by the sun, becomes

hard and compact and constitute the top soil of the region. Due to

unavailability of enough open unused lands, agricultural lands on which the

locals rely for their food needs are also filled up with the ash. Geochemical

studies carried out by Mandal and Sengupta (2005) have shown that the ashes

of Kolaghat contain sufficient amounts of trace elements As, Cu, Pb, Ni, Zn,

Co, V, Sc, Be, Cs and Zr relative to the feed coal. These elements show

significant enrichment in the pond ash relative to their crustal abundance.

Trace elements present in the ash may get incorporated in the top soil from

the wind blown ash particles and also from the ash dumped, since there are no

underground lining beneath the ash pile dumped. Hence in the present study

it was thought pertinent to study the characterize the soil in terms of

mineralogy and geochemistry especially on the basis of heavy metal

concentration as excess concentration of trace elements in the soil is harmful

for the growth of the plants, which will indirectly effect the agriculture of the

region.

The enrichment of individual elements in the top soil around the ash pond was

estimated with respect to the crustal abundance and also with respect to the

background to show the effect of ash deposition on the soil.

Study area




https://www.researchgate.net/publication/237643193_Radionuclide_and_trace_element_contamination_around_Kolaghat_Thermal_Power_Station_West_Bengal_-_Environmental_implications?el=1_x_8&enrichId=rgreq-031e4239858ebf412ce1730613db9966-XXX&enrichSource=Y292ZXJQYWdlOzIyNjI0OTgwNztBUzoxOTkxOTMyMjMyNzQ1MTlAMTQyNDUwMjc3MzcyMg==

The present study was conducted around the ash disposal sites of the Kolaghat

thermal power plant, situated in the Midnapur district of West Bengal, India.

The area under study falls under the Survey of India toposheet No. 73N/15

and is bounded by north latitudes 22°25′ and 22°27′ and east latitudes 87°50′

and 87°55′. The thermal power plant consumes bituminous coal of grade E and

F. It has six units of 210 MW each and generates 1,260 MWe electricity.

The Kolaghat region falls within the Kasai delta of the Upper Holocene Dainkri

formation with dominant lithotypes being laterites with brown and mottled

clays at the top. The major source of potable water for the villages Raksha,

Bahala and Mecheda surrounding the ash pond are the Kasai river, the Denan-

Dehati canal and the tributaries of the Rupnarayan river (Fig. 1a). Earlier, the

fly ash generated was collected from the electrostatic precipitators, but now

both the bottom ash and the fly ash (from the electrostatic precipitators) of the

plant are mixed together and deposited in dry and wet disposal method in the

four large ponds (1A, 1B, 4A, 4B) (Fig. 1b) located 4 km south, south–west and

north–west of the power plant. Ash ponds 1A and 1B are located west and

north–west of the power station and on either side of National Highway NH-6,

whereas the ash ponds 4A and 4B lie to the south of the power plant, on either

side of the railway track. The adjacent areas of ash pond continuously receive

atmospheric fallout and wind blown ash particles from the pond.




Fig. 1

a Location map of the study area. b Location of the sites from where soil samples were collected

Methodology

Sample collection

Topsoil (0–5 cm) samples were collected around the ash ponds from four radial

profiles, 1A1–1A4, 1B1–1B4,4A1–4A4, 4B1–4B4, in each of the ash ponds.

Samples were collected from each profile at regular intervals of 10 m. Besides

the topsoil, soil samples were also colleted from two vertical profiles (D1and

D2) at depths of 0, 25, 50 and 100 cm from the surface. Background soil

samples were collected at distance of about 10 km south of the ash ponds

(Fig. 1b). The background samples are selected from areas which are not

affected by fly ash disposal, i.e. these are the areas where the ash from the

ponds is not dumped by either wet or dry disposal methods. As stated earlier

the ash are dumped 3 km near the power plant, so at 10 km distance the soil is

almost unaffected by ash pile.

Laboratory methods

The soil samples were homogenized by coning and quartering, air-dried at

100–110°C for about 24 h and then finely powdered and sieved using standard

sieves of (70, 100, 140, 200, 270, 325) mesh size before analysing for trace

element concentration using an X-ray fluorescence spectrometer, Philips 1450

and automatic sequential (wavelength) spectrometer equipped with a

Ph-target X-ray tube at IIT Kharagpur. The tube was operated at 45 and

60 kV/50 mA and 60 kV/40 mA for optimum excitation of the analytes.

X-ray diffraction (XRD) analysis of soil and sediments was carried out for

mineral phase identification by Phillips diffractometer (PW 1840) coupled with

X-ray generator (PW 1729), using Cu-Ka. All the samples were run at a tube

voltage of 20 kV and 30 mA. The goniometer speed and chart speed were

maintained at 0.05 2 h and 10 mm/2 h, respectively.

The pH was measured at a solid to liquid ratio of 2:5 using an Orion 1260 Ion

Selective Electrode (ISE). The trace elements in soil samples were determinedFirefox can't load web fonts from a remote host



by using the inductively coupled plasma-mass spectroscopy (ICP-MS), MODEL

Perkin Elmer Sciex ELAN DRC II (Toronto, Canada) at the Central Research

Facility available at National Geophysical Research Institute, Hyderabad,

India. Solutions of the soil samples were prepared by the microwave

dissolution technique. A microwave digestion system, Model MARS-5 (CEM

Corporation, Matthews, NC, USA), equipped with 12 low-volume

perfluoroalkoxy (PFA) lined vessels, with safety rupture membranes (maximum

operating pressure 1,380 Kpa), was used for microwave dissolution. A rhodium

solution of 1 mg/l concentration was added as 10% v/v as an internal standard

(Balaram 1993). International soil reference materials were used to prepare

calibration curves for different trace metals and to check the accuracy of the

analytical data. Canadian soil reference materials SO-1, SO-2, SO-3 and SO-4

were used to estimate the analytical bias of the soil data. The detection limits

for all the trace elements were better than 1 ng/ml (Govil et al. 1997). The

precisions obtained for most of the trace elements data was <5% RSD with

comparable accuracy (Balaram 1993).

Results and discussions

Mineralogy

Size analysis of the samples show that majority of the soil samples were in the

range of 149–105 μm and <53 μm. Size classification shows that the soils upto

100 cm depth in all the profile as well as the top soils are of fine sand to silt to

clay range. The X-ray diffractogram of the bulk soils samples from the profiles

around the ash ponds are shown in Fig. 2a, b. It is seen that the major

mineralogical phases identified in the soil were kaolinite, illite, mullite and

quartz. The diffractograms of the samples from 4A, 4B, indicated the presence

of mullite (3Al2O3·2SiO2) as one of the major mineralogical phases. The

presence of mullite in the X-ray diffractograms of the topsoil from profiles 4A,

4B is a striking observation. Mullite, a common mineral in coal ash, is

normally not found in natural soils (Lumsdon et al. 2001). Mullite is also

present in the X-ray diffractograms of the ash samples of the study area

(Mandal and Sengupta 2002, Fig. 3). Hence its presence in the top soil could

be attributed mainly to the contribution either from the wind blown ash

particles or from the ash dumped.Firefox can't load web fonts from a remote host



https://www.researchgate.net/publication/222320307_Use_of_solid_phase_characterization_and_chemical_modeling_for_assessing_the_behaviour_of_arsenic_in_contaminated_soils_Appl_Geochem?el=1_x_8&enrichId=rgreq-031e4239858ebf412ce1730613db9966-XXX&enrichSource=Y292ZXJQYWdlOzIyNjI0OTgwNztBUzoxOTkxOTMyMjMyNzQ1MTlAMTQyNDUwMjc3MzcyMg==

https://www.researchgate.net/publication/285427282_Characterization_of_trace_elements_in_environmental_samples_by_ICP-MS?el=1_x_8&enrichId=rgreq-031e4239858ebf412ce1730613db9966-XXX&enrichSource=Y292ZXJQYWdlOzIyNjI0OTgwNztBUzoxOTkxOTMyMjMyNzQ1MTlAMTQyNDUwMjc3MzcyMg==


Fig. 2

X-ray diffractogram of top soil around ash pond 4A and 4B




Fig. 3

XRD pattern of pond ash from the ash ponds of Kolaghat

Chemical composition of the top soils from the four soil profiles

The pH of the soil was in the acidic range 4.5–5.2 in all the soil samples

studied. The pH of ash deposited was also acidic in nature ie 4.5. The pH of

the background soil was alkaline (8.2), which showed that the acidic nature of

the pH of the soils near the ash ponds was due to the effect of ash disposal.

The top soils of all the soil profiles from all the ash ponds are characterized by

dominance of SiO2 followed by Al2O3, Fe2O3, K2O and TiO2 as seen in Table 1.

The trace elements analysed in the profile soils around the four ash ponds and

the background soils are shown in Table 2. The trace elements in decreasing

order of abundance in all the soil profiles around the four ash ponds are Mn,

Ba, Rb, Sr, V, Zn, Cr, Ni, Cu, Pb, Mo, Be and As. It is observed that the element

concentrations are varying from profile to profile around the ash pond while

their variations within the same profile did not show any particular trend.

Among the trace elements Mn, Ba, V, Cr, Cu, Zn Pb showed much higher

concentrations in the top soils from all the profiles around the four ash ponds

than the background soils.




Table 1

Major and minor oxides (wt%) in the top soils from the soil profiles around the four ash ponds (1A, 1B, 4Aand 4B)

SiO2 Al2O3 TiO2 Fe2O3 CaO MgO K2O P2O5

1B1 62.11 10.01 1.79 4.50 2.03 1.30 2.89 0.29

1B2 63.10 11.02 1.52 4.67 2.21 1.32 2.92 0.28

1B3 64.10 12.12 1.67 4.56 2.12 1.29 2.95 0.27

1B4 62.21 10.32 1.56 4.64 2.03 1.19 2.98 0.29

Average 62.88 10.87 1.64 4.59 2.10 1.28 2.94 0.28

1A1 62.11 12.22 1.32 4.23 2.32 1.23 2.12 0.32

1A2 64.10 12.32 1.54 3.67 2..30 1.29 2.23 0.29

1A3 63.10 13.21 1.45 3.98 2.39 1.28 2.34 0.3

1A4 62.21 11.09 1.53 4.1 2.56 1.31 2.29 0.31

Average 62.88 12.21 1.46 4.00 2.42 1.28 2.25 0.31

4A1 62.11 11.01 1.89 4.56 2.12 1.45 2.89 0.29

4A2 64.10 12.30 1.72 4.67 2.34 1.42 2.92 0.28

4A3 69.11 12.12 1.67 4.63 2.45 1.38 2.95 0.27

4A4 72.10 10.32 1.56 4.64 2.56 1.41 2.98 0.29

Average 66.80 11.44 1.71 4.62 2.37 1.42 2.94 0.28

4B1 66.11 12.22 1.32 4.23 2.45 1.32 2.12 0.32

4B2 64.11 12.32 1.54 3.67 2.65 1.39 2.23 0.29

4B3 68.10 13.21 1.45 3.98 2.78 1.54 2.34 0.3

4B5 62.21 11.09 1.53 4.10 2.56 1.52 2.29 0.31Firefox can't load web fonts from a remote host



Table 2

Trace elements in the top soils from the four profiles around the four ash ponds (1A, 1B, 4A and 4B) and thebackground soil (BG) (all values in ppm)

Sampleno.

Trace elements

Be V Cr Mn Ni Co Cu Zn

1B1 4.36 127.00 97.40 1260.00 71.63 20.29 84.05 210.30

1B2 4.31 135.00 123.41 1265.00 62.19 21.50 89.74 218.02

1B3 4.33 140.00 70.40 1264.00 37.22 13.97 66.15 164.89

1B4 4.35 145.00 122.54 1261.00 49.14 20.67 54.15 185.35

Average 4.34 136.75 103.44 1262.50 55.05 19.11 73.52 169.64

1A1 4.33 125.84 95.75 1208.00 45.92 17.86 57.87 99.82

1A2 3.85 115.49 73.73 1250.00 40.73 14.16 57.87 137.36

1A3 4.31 115.61 96.29 1210.00 45.87 19.42 59.00 91.87

1A4 4.18 137.03 102.61 1220.00 56.05 19.28 59.38 183.25

Average 4.17 123.49 92.09 1222.00 47.14 17.68 58.53 128.08

4A1 5.63 155.00 105.40 1500.00 76.63 27.86 84.05 219.30

4A2 5.44 152.00 131.41 1529.00 67.19 24.16 89.74 227.02

4A3 4.82 150.00 78.40 1520.00 42.22 29.42 86.15 173.89

4A4 5.43 158.00 130.54 1521.00 54.14 31.10 84.15 94.35

Average 5.33 153.75 111.44 1517.50 60.05 28.13 86.02 178.64

4B1 5.33 142.00 121.00 1390.00 45.92 20.29 77.87 79.82

4B2 4.85 143.00 73.73 1500.00 40.73 21.50 59.00 70.82

4B3 5.31 134.00 96.29 1520.00 45.87 23.00 56.72 137.36Firefox can't load web fonts from a remote host



Trace elements in the depth profiles

The concentrations of trace elements in soils collected with depth (e.g., 0, 25,

50, 75 and 100 cm) from two profiles (D1) and (D2) are shown in Table 3,

Fig. 4a, b. It is seen in that in all the depth profiles (D1 and D2), the

concentration of the trace elements decreases with depth. The concentration

of the trace elements Mn, Ba, V, Cr, Cu, Zn, As decreases below the surface

layer, i.e. from 0 to 25 cm. It is significant to note that all these elements are

abundantly present in the coal ash and are enriched 2–10 times with respect

to their crustal abundances (Table 4). The pond ash, which is mixed with the

top soil layer in all the ash ponds, is characterized by high concentrations of

toxic trace elements (As, Cd, Cr, Ni, Co, Cu, Sb, V, Zn, Mn, Mo) (Mandal and

Sengupta 2002). Therefore, it may be inferred that the topsoil, with high

concentration of trace elements in both the depth profiles, is possibly

contaminated by ash from the pond. Since there are no other industrial

emissions in the study area, the high concentrations of the trace elements in

the top soils implies input from the ash piles, which lie uncovered and exposed

to the atmosphere. Wind blown ash particles are easily carried away due to

their fineness and deposited as a layer on the top soils of the surrounding

areas.




Table 3

Variation of element concentrations in the depth profiles D1 and D2 (all values in ppm)

Profiles D1 D2

Depth(cm)

0 25 50 75 100 0 25

Elements Concentration (ppm)

Be 4.34 3.75 2.90 2.78 1.66 5.33 2.78

V 132.02 127.20 112.32 97.91 90.05 153.75 140.37

Cr 107.58 103.44 94.35 83.71 79.71 111.44 104.23

Mn 1,262.50 1,032.21 921.92 897.63 873.34 1,321.00 1,201.00

Ni 55.05 45.47 41.92 34.35 27.78 71.08 66.05

Co 19.11 18.82 18.54 18.26 17.97 28.13 24.61

Cu 90.38 73.52 69.55 56.99 46.57 94.94 86.02

Zn 169.64 163.21 156.78 150.35 143.93 178.64 169.53

As 4.67 4.12 3.45 2.86 2.25 3.98 2.47

Rb 166.32 164.33 162.34 160.35 158.35 234.25 214.58

Sr 126.63 120.16 115.46 110.50 10.8.20 154.12 150.01

Mo 8.57 6.21 6.16 5.57 4.37 7.05 5.75

Ba 666.25 654.00 650.00 640.50 632.38 684.47 654.00

Pb 25.24 23.07 16.23 14.02 12.21 35.57 30.14

U 8.39 7.91 6.40 5.40 4.87 7.91 6.40

Th 28.63 25.29 24.70 21.12 20.12 22.01 2012.00




Fig. 4

a Depth wise distribution of (Ba, Mn) in the two soil profiles D1 and D2. b Depth wise distribution of (Be, As,Mo, Ni, Co, Cr, Cu, Pb, V, Zn, Rb, Sr) in the two soil profiles D1 and D2




Table 4

Concentration of trace elements and their enrichment factor is pond ash

Trace elements in pond ash Concentration (ppm) EF (ash)

Mn 5,459.19 10.28

Cr 135.1 4.32

Mo 13.16 9.81

Cd 0.91 10.43

Be 5.87 2.19

Sc 34.2 3.48

V 195.75 3.65

Co 33.33 3.71

Ni 60.11 3.36

Cu 86.71 3.88

Zn 119.53 1.88

As 10.03 7.01

Rb 253.87 2.53

Sr 269.26 0.86

Zr 822.84 4.84

Ba 1,052.2 2.14

Pb 94.75 5.30

Enrichment of elements




(1)

(2)

The enrichment factors (EFs) for different elements in topsoil were calculated

with respect to their crustal abundance (Taylor and McLenan 1985) and

background concentration. The EF was calculated by using different formulae

as given below:

where (C i /C Si)soil = (Concentration of ‘i’/Concentration of Si) in soil, (C i /C

Si)Crust = (Concentration of ‘i’/Concentration of Si) in the crust, (C i /C Si)BG =

(Concentration of ‘i’/Concentration of Si) in the background soils.

For the calculation of EF with respect to the crust and the background, silicon

(Si) was used for normalization as it is known to be very stable in the

geochemical environment of the crust. The enrichment factors of the trace

elements with respect to the crust are shown in Table 5. With respect to the

crust, all the EF values were within the range of 0.4 to 5.8. The higher values

were for Mn (2.1–2.6), Mo (3.8–5.8), Cr (2.6–3.2), Cu (2.5–3.5), As(1.9–3.8),

V(2.1–2.6), Zn (1.8–2.5), Co (1.8–2.8) and Ni (2.4–3.0). Table 6 shows the

enrichment factors of the trace elements and the radionuclides with respect to

the background soils. With respect to the background soils, all the elements

showed EF values were within the range of 0.9–6.5. The higher values were

for Mn (2.1–2.7), Ba (4.5–4.9), V (5.3–6.5), Cu (4.1–5.6), Zn (3.4–5.2). The

enrichment of all the elements in the top soil attributed to their input from ash

from the disposal pond and by wind blown ash particles.

EF in soil with respect to crust (EF) = ,( /Ci CSi)Soil

( /Ci CSi)Crust

EF in soil with respect to background = ,( /Ci CSi)Soil

( /Ci CSi)BG




Table 5

Enrichment factor (EF) of the trace elements in the top soils with respect to the crust

Elements

EF

1A 1B 4A 4B

Be 1.4 1.4 1.8 1.8

V 2.1 2.3 2.6 2.3

Cr 2.6 3.0 3.2 2.8

Mn 2.1 2.1 2.6 2.5

Ni 2.4 2.8 3.0 2.4

Co 1.8 1.9 2.8 2.1

Cu 2.5 3.0 3.5 2.5

Zn 1.8 2.4 2.5 1.7

As 1.9 2.2 3.8 2.3

Rb 1.5 1.5 1.8 1.7

Sr 0.4 0.4 0.4 0.4

Mo 3.8 5.7 5.8 4.7

Ba 1.2 1.2 1.2 1.2

Pb 1.1 1.2 1.8 1.3




Table 6

Enrichment factor (EF) of the trace elements in the top soils with respect to the background

Elements

EF

1A 1B 4A 4B

Be 3.5 3.6 4.4 4.4

V 5.3 5.8 6.5 5.8

Cr 1.3 1.5 1.6 1.4

Mn 2.1 2.2 2.7 2.6

Ni 1.8 2.1 2.3 1.8

Co 0.9 1.0 1.5 1.1

Cu 4.1 4.8 5.6 4.1

Zn 3.7 4.9 5.2 3.4

As 2.7 3.1 5.4 3.4

Rb 1.1 1.1 1.3 1.3

Sr 1.1 1.1 1.3 1.1

Mo 0.9 1.3 1.3 1.1

Ba 4.5 4.8 4.9 4.7

Pb 1.5 1.5 2.4 1.7

From the above observations, it is inferred that Zn, Cu, Ni, Co, Mo, Mn, Cr, V,

and Ba are enriched in the topsoil around the ash pond to varying degrees

with respect to the crust as well as the background. Interestingly, all these

elements are enriched in concentration in the pond ash with respect to the

crust. Being fine grained (fine sand to silt sizes) the ash particles are easily

carried by the wind. These elements showed prominent enrichment in the topFirefox can't load web fonts from a remote host



soils in the profiles within or close to the predominant wind direction, i.e. SW.

The ash ponds 1B, 4A and 4B are in the south westerly direction of the power

plant. Moreover the profiles from which soil samples were collected all lie to

the SW of the above mentioned ash ponds. Hence the soils from these profiles

show greater enrichment of trace elements due to input of ash blown by the

wind than those near ash pond 1A, which lies against the prevalent wind

direction. Since the profiles are in a south and south westerly direction of the

ash ponds, the top soils from these profiles show higher concentration of the

trace elements.

Log-normal distribution plots

Heavy metal distribution in sediments closely follow the log-normal law

(Sinclair 1981). The frequency distribution of pollutants in soils, sediments

could be examined using the log-normal distribution plots. Forstner (1983)

stated that background values, serving as thresholds between polluted and

unpolluted areas, can be derived from the log-normal distribution plots. For

metal distributions in which linearity is not observed, a break point

delineating inflection of the curve is arbitrarily fixed and the corresponding

concentration is used to represent an operational threshold between polluted

and non-polluted (or slightly polluted) areas. The theory of Sinclair have been

used in the present study to assess the extent of pollution of the soils of the

study area from the wastes of the power plants. Log-normal distribution plots

for element concentrations in surface soils of all the locations have been

delineated following Celo et al. (1998) and are shown in Fig. 5. From the plots

it is seen that the values of the square of the correlation coefficients (R 2)

range from 0.85 to 0.97.




https://www.researchgate.net/publication/226975362_An_Assessment_of_Heavy_Metal_Pollution_in_the_Sediments_Along_the_Albanian_Coast?el=1_x_8&enrichId=rgreq-031e4239858ebf412ce1730613db9966-XXX&enrichSource=Y292ZXJQYWdlOzIyNjI0OTgwNztBUzoxOTkxOTMyMjMyNzQ1MTlAMTQyNDUwMjc3MzcyMg==

Fig. 5

Log-normal distribution plots of the trace elements in the top soils from the profiles near the ash ponds ofKolaghat thermal power plant

The distributions of Mn, As, Co, Cu, Pb, Ba, Ni shows poor linearity (R 2 are

0.85, 0.84, 0.90, 0.90, 0.90, 0.86, and 0.91, respectively), suggesting a

significant impact of anthropogenic activity in their distribution. The most

common source of anthropogenic activity in these areas is the disposal of ash

from the thermal power plant. The inflection point is well defined in the

distribution plots of the above mentioned trace elements. The other trace

elements Be, V, Cr, Rb, Sr Mo and Zn also show poor but slightly better

linearity (R 2=0.93, 0.94, 0.96, 0.97, 0.93, 0.93 and 0.95). Their distribution isFirefox can't load web fonts from a remote host



also to a large extent affected by the polluting sources, but the contrast

between polluted and unpolluted sources with respect to the above mentioned

elements is not very well defined.

Conclusions

The present work thus show significant amount of contamination of the top

soil due to ash disposal. The contamination is more pronounced in the soils

within or close to the predominant wind direction. The concentrations of all

the trace elements in all the soil profiles around the ash pond are higher than

the background. The order of concentrations of Mn, Ba, V and Cr in profile

soils is similar to that found in pond ash. The physicochemical and

mineralogical properties of the profile soil in the predominant wind direction

are found to be modified compared to the background and other profile soils.

pH of the soil is lowered by the addition of ash from the power plant. A soil pH

below about 5.6 is considered low for most crops. At these low pH’s, the

solubility of aluminium, iron, and boron is high; Many heavy metals become

more water soluble under acid conditions and can move downward with water

through the soil, and in some cases move to aquifers, surface streams, or

lakes. Hence disposal of ash affects the agricultural quality of the soil.

Mullite, one of the major mineral phases in coal ash, has also been detected in

these soils. The anomalous presence of mullite in the profile soils has been

attributed to ash input through local anthropogenic activity, which was

observed in the field. Statistical treatment of the soil data further strengthens

the extent of contamination of the soils. This causes greater concern for

agricultural activities in the region which is located in a densely populated and

highly industrial zone Plants growing on these soils may incorporate theses

trace elements through uptake by the roots, and thus may enter into the food

chain of animals who consumes these plants. The metal input to the

surrounding topsoil is expected to continue unabated as the ash pond

continues to be filled more and more with the ash which ultimately forms the

topsoil. Praharaj et al. 2003 have also shown contamination of soil from ash of

a thermal power plant at Angul, Orissa. The soils near the ash ponds of Angul,

when analysed for trace elements showed that with respect to the crust, the

EF values of the trace elements were within the range of 0.2 to 31. The higher

values were for Mn (0.8–31.8) followed by Ba (1.4–8.1), Pb (1.5–6.3), V

(0.7–3.7), Cr (0.8–2.9), Cu (0.2–2.5), Zn (0.3–2.4), Co (0.4– 2.1) and NiFirefox can't load web fonts from a remote host



https://www.researchgate.net/publication/225711718_Geochemical_studies_to_delineate_topsoil_contamination_around_an_ash_pond_of_a_coal-based_thermal_power_plant_in_India?el=1_x_8&enrichId=rgreq-031e4239858ebf412ce1730613db9966-XXX&enrichSource=Y292ZXJQYWdlOzIyNjI0OTgwNztBUzoxOTkxOTMyMjMyNzQ1MTlAMTQyNDUwMjc3MzcyMg==

(0.2–0.9). The enrichment of all the elements in the topsoil around the ash

pond is attributed to their input from ash from the disposal pond, almost

similar to the present work.

The present work thus helps to delineate the areas of contamination around

the ash ponds which will further help to develop remedial measures to combat

the problem.

References

Baba A (2002) Assessment of radioactive contaminants in by-products from

Yatagan (Mugla, Turkey) coal-fired power plant. Environ Geol 41:916–921

CrossRef

Balaram V (1993) Characterization of trace elements in environmental

samples by ICP-MS. At Spectrosc 14(6):174–179

Bertine KK, Goldberg ED (1971) Fossil fuel combustion and the major

sedimentary cycle. Science 173:233–235

CrossRef

Bilski JJ, Alva AK, Sajwan KS (1995) Fly ash. In: Rechcigl JE (ed) Soil

amendments and environmental quality. Lewis Publishers, New York, pp

327–361

Bityukova L, Shogenova A, Brike M (2000) Urban geochemistry: a study of

element distributions in the soils of Tallinn (Estonia). Environ Geochem Health

22:172–193

CrossRef

Carlson CL, Adriano DC (1993) Environmental impacts of coal combustion

residues. J Environ Qual 22:227–247

CrossRef

Celo V, Babi D, Baraj B, Cullaj A (1998) An assessment of heavy metal pollution

in the sediments along the Albanian coast. Water Air Soil Pollut 85:235–249

EIA (2002) World Production of Primary Energy by Selected Country GroupsFirefox can't load web fonts from a remote host












(Btu), 1991–2000. Energy Information Administration, U.S. Department of

Energy. http://www.eia.doe.gov/emeu/iea/table29.html

Forstner U (1983) Applied environmental geochemistry. Academic Press,

London, p 395

Fytianos K, Tsaniklidi B, Voudrias E (1998) Leachability of heavy metals in

Greek fly ash from coal combustion. Environ Int 24:477–486

CrossRef

Govil PK, Gnaeswara Rao T, Rao R (1997) Environmental monitoring of toxic

elements in an industrial development area: a case study. In Abstract vol 3,

International Conference on Analysis of Geological and Environmental

Materials, Vail, Colorado, p 77

Gulec N, Gunal (Calci) B, Erler A (2001) Assessment of soil and water

contamination around an ash-disposal site: a case study from the Seyitomer

coal fired power plant in western Turkey. Environ Geol 40(3):331–344

CrossRef

Jones KC (1991) Contamination trends in soils and crops. Environ Pollut

69:311–325

CrossRef

Kim K, Kim S (1998) Heavy metal pollution of agricultural soils in central

regions of Korea. Water Air Soil Pollut 82:109–122

Lumsdon DG, Meeussen JCL, Paterson E, Garden LM, Anderson P (2001) Use

of solid phase characterization and chemical modeling for assessing the

behavior of arsenic in contaminated soils. Appl Geochem 16:571–581

CrossRef

Mandal A, Sengupta D (2002) Characterisation of coal and fly ash from

coal-fired thermal power plant at Kolaghat—possible environmental hazards.

Indian J Environ Prot 22(8):885–891

Mandal A, Sengupta D (2005) Radionuclide and trace element contamination

around Kolaghat thermal power plant, West Bengal. Curr Sci 88(4):617–624

Mukherjee SN, Nag AK (1997) Bulk use of fly ash for the manufacture of

building materials. In: Tripathy PS, Mukherjee SN (eds) Perspectives on bulkFirefox can't load web fonts from a remote host














use of fly ash. Allied Publishers, New Delhi, pp 5–86

Parekh PP, Husain L (1987) Fe/Mg ratio: a signature for local coal-fired power

plants. Atmos Environ 21(8):1707–1712

CrossRef

Pichtel J, Sawyerr HT, Czarnowska K (1997) Spatial and temporal distribution

of metals in soils in Warsaw, Poland. Environ Pollut 98(2):169–174

CrossRef

Praharaj T, Swain SP, Powel MA, Hart BR, Tripathy S (2001) Geochemical and

GIS study on contamination of topsoil around an ash pond. International

Symposium on Applied Geochemistry in the Coming Decades, Indian Society of

Applied Geochemists, Osmania University, Hyderabad, pp 94–95

Praharaj T, Tripathy S, Powel MA, Hart BR (2003) Geochemical studies to

delineate topsoil contamination around an ash pond of a coal-based thermal

power plant in India. Environ Geol 85:86–97

CrossRef

Ramachandran TV, Lalit BY, Mishra UC (1990) Modifications in natural

radioactivity contents of soil samples around thermal power stations in India.

Indian J Environ Health 32:13–19

Russal MB (1957) Physical properties in soil. US Agricultural Year Book,

Washington DC, pp 31–38

Satyanarayana Raju MV (1993) Pollution status of soils near ash pond of a

thermal power station. Indian J Environ Health 35(1):9–14

Sharma VK, Rhudy KB, Cargill JC, Tacker ME, Vazquez FG (2000) Metals and

grain size distributions in soil of the middle Rio Grande basin, Texas, U S A.

Environ Geol 39(6):698–704

CrossRef

Shi B, Sengupta A (1995) Leaching behavior of fly ash piles: the phenomenon

of delayed rise in toxic concentrations. J Environ Syst 24:87–93

Sinclair AJ (1981) Applications of probability graphs in mineral exploration,

vol 4, Richmond Printers Ltd, p 95















Sterckeman T, Douay F, Proix N, Fourrier H (2000) Vertical distribution of Cd,

Pb and Zn in soils near smelters in the north of France. Environ Pollut

107:377–389

CrossRef

Taylor SR, McLenan SM (1985) The upper crust. In the continental crust.

Balckwell, Oxford, p 312

Theis TL, Gardner HK (1990) Environmental assessment of ash disposal. Crit

Rev Environ Control 20(1):21–42

CrossRef

Theis TL, Westrick JD, Hsu CL, Marley JJ (1978) Field investigation of trace

metals in groundwater from fly ash disposal. J Water Pollut Control Fed

50:2457–2469

Ullrich SM, Ramsey MH, Helios-Rybicka E (1999) Total and exchangeable

concentrations of heavy metals in soils near Bytom, an area of Pb/Zn mining

and smelting in upper Silesia, Poland. Appl Geochem 14:187–196

CrossRef

Vijayan V, Behera SN (1999) Studies on natural radioactivity in coal ash. In:

Mishra PC, Naik A (eds) Environmental management in coal mining and

thermal power plants. Technoscience, Jaipur, pp 453–456

Yarlagadda PS, Matsumoto MR, VanBenschoten JE, Kathuria A (1995)

Characteristics of heavy metals in contaminated soils. J Environ Eng

121(4):276–286

CrossRef

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