Jordan Journal of Chemistry Vol. 7 No.4, 2012, pp. 349-363

349

JJC

Persistent Organic Pollutants in Soil Samples from Industrial Vicinity East of Zarqa City, Jordan

Ibrahim Tarawneh, Yahya Kusbe, Mahmoud Alawi∗

Faculty of Science, Department of Chemistry, University of Jordan, Amman-11942, Jordan.

Received on June 2, 2012 Accepted on Nov. 12, 2012

Abstract The levels of 13 Polyaromatic hydrocarbons (PAHs) and 12 Polychlorinated biphenyls

(PCBs) were determined in 23 soil samples collected from the vicinity of the Jordan petroleum

refinery and Al-Hussein thermal power stations in Zarqa region. The total concentrations of

PAHs were ranged between 0.94 µg/kg (site 13) and 191 µg/kg (site 19), while none of the

samples was containing any of the studied PCBs. Recoveries of PAHs and PCBs were found

between 82 -106% and 91-114% respectively. Precision of the method for both PAHs and

PCBs, calculated as relative standard deviation (RSD) was ranged between 0.6 – 7%. The limit

of detection for PAHs and PCBs were between 0.006- 0.070 µg/kg and 0.149-0.330 µg/kg

respectively. The total estimated cancer risks of exposure to PAHs in the soil samples were

ranged from 8.56 × 10-9 to 5.53 × 10-6. By multiplying these numbers of cancer risks of

exposure to soil sample-PAHs by 106, it is possible to determine the maximum theoretical

number of cancer cases per million of people. The maximum estimated cancer risks cases

determined in this study (6 out of million) are well within the acceptable range of excess cancer

risk specified by the US Environmental Protection Agency. In general, the studied area shows

very low pollution level.

Keywords: Cancer risk; Jordan; PAHs; PCBs; Soil; Zarqa.

Introduction Petrochemical industries have been identified as important emission sources of

environmental pollutants. Significant amounts of organic contaminants such as volatile

organic compounds, polyaromatic hydrocarbons (PAHs) and polychlorinated biphenyls

(PCBs) have been also detected in the environment. In turn, some epidemiological

studies have pointed out the possibility that the presence of this kind of facilities could

induce leukemia, as well as bone, brain, and bladder cancers [1].

Soil pollution is increasingly become a large problem which confront the humans

since the industrial revolution. Before soil pollution can be stopped, the sources of

pollution must be identified. The major sources of soil pollution are Persistent Organic

Pollutants (POPs) like polychlorinated biphenyls (PCBs) and polyaromatic

hydrocarbons (PAHs). Those POPs are ubiquitous environmental contaminants

derived from incomplete combustion of organic materials, e.g.: fossil fuels including

∗ Corresponding author: E-mail: alawima@ju.edu.jo, Phone: +962 777483679, Fax: +962 65300253.

350

petroleum refining. POPs are becoming more and more pressing on the environment

because of the growing population [2].

PCBs became available as industrial chemicals since 1930, their widespread

application in the subsequent 50 years, has resulted in their presence as persistent

and ubiquitous environmental contaminants and/or pollutants. Their potential

carcinogenic, mutagenic, teratogenic effects, their high chemical stability and

lipophilicity, and thus consequent bioaccumulation, have made their monitoring very

important in environmental research [3, 4, 5].

PCBs were commercially produced as complex mixtures at the beginning of

1929 and continued up to l970s. The production by Monsanto, the major world

manufacturer, was ceased in 1977. All of the commercial mixtures were synthesized

by direct chlorination of biphenyl with chlorine gas in the presence of AlCl3. And it has

been found that the average degree of chlorination was controlled by the reaction

conditions to yield the desired physical and chemical properties [6]. Since PCBs are

relatively nonflammable and have useful heat exchange and dielectric properties, they

have been used in a wide variety of applications [7, 8, 9].

According to literature the optimal value of dioxins/furans and PCBs for a soil

should be below 5 ng WHO-TEQ/ kg. Values greater than 100 ng WHO-TEQ/ kg are

considerd relatively high and reduces the possibility of using the soil, due to

contamination and level of toxicity [10].

PAHs are ubiquitous environmental contaminants derived from the incomplete

combustion of organic materials, e.g. any kind of fossil fuels. Due to carcinogenic and

mutagenic activity of many representatives of this group of compounds, PAHs pollution

has become a serious environmental problem. That is why the concentration of PAHs

in all compartments of the environment, i.e., water, soil and air, is regulated in most

countries of the world. Many PAHs are included in the “priority pollutants” listing of the

US EPA and European Commission (Regulation EC No 166/2006). Usually, solid

wastes contain hazardous trace compounds, including PAHs as a specific group of

POPs include a wide range of compounds: carboxylic and heterocyclic, substituted and

non-substituted homologues. For simplification of the analysis and regulation purposes

it was reasonable to select a set of priority pollutants of PAHs, to which the criteria

were stated [11].

One of the most important properties of PAHs concerning the analytical

determination appears to be the water solubility. As a rule, PAHs water solubility

decreases (and hydrophobic interaction increases) with the increase in the number of

fused benzene rings, and with angularity. Thus, high-molecular mass compounds are

more slowly desorbed from the matrix and dissolved in an appropriate solvent than

low-molecular mass PAHs. Volatilization generally decreases with increasing the

number of fused rings [http://www.ispac.org/Links.htm]. Risk assessment can be

evaluated by incremental lifetime cancer risk (ILCR) associated with exposures to

351

PAHs in soil samples using the US EPA standard models. The cancer risk was

assessed based on exposure according to type of land over the entire lifetime [12, 13, 14].

This study aims to give both qualitative and quantitative information and

establishing a base line data for POPs pollutants at the vicinity of the Jordan petroleum

refinery and Al-Hussein Thermal power station which are located in Zarqa region ca.

35 km northeast of the Capital Amman.

Materials and Methods Chemicals and Reagents

A standard mixture of PCBs containing the following 12 PCB congeners:

(1) 3, 3’, 4, 4’-Tetrachlorobiphenyl (PCB-77)

(2) 3, 4, 4’, 5-Tetrachlorobiphenyl (PCB-81)

(3) 2, 3, 3’, 4, 4’-Pentachlorobiphenyl (PCB-105)

(4) 2, 3, 4, 4’, 5-Pentachlorobiphenyl (PCB-114)

(5) 2, 3’, 4, 4’, 5-Pentachlorobiphenyl (PCB-118)

(6) 2', 3, 4, 4’, 5-Pentachlorobiphenyl (PCB-123)

(7) 3, 3’, 4, 4’, 5-Pentachlorobiphenyl (PCB-126)

(8) 2, 3, 3’, 4, 4’, 5-Hexachlorobiphenyl (PCB-156) (9) 2, 3, 3’, 4, 4’, 5’-Hexachlorobiphenyl (PCB-157)

(10) 2, 3’, 4, 4’, 5, 5’-Hexachlorobiphenyl (PCB-167)

(11) 3, 3’, 4, 4’, 5, 5’-Hexachlorobiphenyl (PCB-169) (12) 2, 3, 3’, 4, 4’, 5, 5’-Heptachlorobiphenyl (PCB189) was purchased from Dr. Ehrenstorfer (Augsburg, Germany), and a standard mixture of

PAHs containing the following 13 compounds: Acenaphthylene, Fluorene,

Phenanthrene, Anthracene, Pyrene, Benzo(a)anthracene, Chrysene, Benzo-

(b)fluoranthene, Benzo(k)fluoranthene, Benzo(a)pyrene, Indeno(1,2,3 cd)pyrene,

Dibenzo(a,h)anthracene, Benzo(g,h,i)perylene was purchased from Supelco (USA).

The internal standards 1, 8- dichloronaphthalene (1 mg/L) which was used for the

analysis of PCB and 1-fluoronaphthalene (1mg/L) which was used for the PAH-

analysis were purchased from Aldrich (USA).

The Silica Gel 60 and aluminum oxide (alumina B super I) chromatography

grade were purchased from ICN (Eschwege, Germany), Florisil (60 - 100 mesh) for

chromatography was purchased from SDS (Peypin, France). All adsorbent materials

were dried at 220oC prior to use. The following solvents of GC- grade were purchased

from Riedel-de Haën (Germany) and used as received: n-hexane, toluene and

dichloromethane.

Sampling and Sample Locations

Twenty three samples were collected from the area around the Jordan Petroleum

Refinery and Al-Hussein thermal power station in Zarqa as shown in figure 1. The

sampling locations were ca. 100 m apart from each other. Each sample consists of 5-8

portions, each of ca. 100 g was taken within an area of ca. 4 m2 and from a depth of

352

ca. 0-10 cm. the portions were pooled in the laboratory, crushed and sieved using a

sieve of 1.2 mm.

Sample Extraction and Clean-Up (PAHs)

Ten grams of each homogenized soil sample were extracted in a soxhlet

apparatus, for 16 hours using 150 ml toluene. The extracts were then evaporated

using the rotary evaporator at 40˚C and 78 mbar to about 3 ml. The raw extract was

cleaned up according to C.P.E.T [15] method with a slight modification. A glass column

(30 x 1.6 cm) was prepared as follows: 11 g of dry (220 °C, 2h) silica gel (72-250

mesh) were filled into the column, 1 gram of 5% deactivated alumina then 2 g of

anhydrous sodium sulfate were added. This column was washed with 50 ml

dichloromethane and 30 ml n-hexane. The residues from the extraction step were

added to the column and eluted with 23 ml n-hexane (alkane fraction/ discard). The

PAHs were eluted from the column with 25 ml (1:1) n-hexane: dichloromethane. The

eluate was evaporated at 40°C and 335 mbar to 1ml, then to dryness using a gentle

stream of nitrogen. The residues were dissolved in 500 µL n-hexane containing 1

µg/ml internal standard (1-Fluoronaphthalene) then transferred into 500 µL screw cap-

vial with a glass inserts and 2 µL were injected onto the GC/MSD- column.

Figure 1: Sampling locations

Sample Extraction and Clean-Up (PCBs)

Each sample was analyzed three times (weighing, soxhlet extraction and silica-

column clean up) and each extract was injected three times onto GC/MS.

Ten grams of each homogenized soil sample were extracted in a soxhlet

apparatus, for 16 hours using 150 ml toluene. The extracts were then evaporated

353

using the rotary evaporator at 40⁰C and 78 mbar to about 3 ml. The raw extract was

cleaned up according to Wenzel method [16] with slight modification. A glass column

(30 x 1.6 cm) was filled in the following order: 11 g of dry (220 °C, 2h) florisil (60-100

mesh) then 2 g of anhydrous sodium sulfate. This column was washed with 20 ml of a

mixture of (1:1) dichloromethane: n-hexane. The residues from the extraction step

were added to the column and eluted with 150 mL of the above mixture. The eluate

was evaporated at 40°C and 335 mbar to ca. 1ml, then to dryness using a gentle

stream of nitrogen and reconstituted in 500 µL n-hexane containing 1µg/mL internal

standard (2,8-dichloronaphthalene), then transferred into 500 µL screw cap-vial with a

glass inserts and 2 µl were injected onto the GC-MSD column.

Chromatographic Conditions and MS-Detection

The GC-MS analysis was carried out using an HP 6890 gas chromatograph and

an HP 5973 quadrupole mass spectrometer from Agilent Technologies (Waldbronn,

Germany). For chromatographic separation a (5%-phenyl)-methylpolysiloxane column

(DB5-MS, 30 m, 0.25 mm I.D., 0.25 µm film thickness) from Agilent Technologies was

used. The carrier gas was Helium of the purity 99.999%. The injected volume for both

analytes was 2 µL. The injection port and transfer line temperatures were set at 250oC

and 280oC, respectively. The carrier gas flow rate was set at 1mL/ min for both

methods. The temperature program for PAHs method was: start at 100oC (held for 10

min), set at a rate of 25oC/min up to 160oC, finally at a rate of 5oC /min up to 265oC

(held for 17 min). The temperature program for PCBs method was: start at 100oC (held

for 1 min), heat at a rate of 30oC/min up to 160oC, then at a heating rate of 5oC/min up

to 260oC (held for 25 min). Mass spectrometric measurements with electron ionization

(EI) at 70 eV were performed in the selected ion monitoring mode (SIM). Figure 2 and

figure 3 show the chromatograms of the standard mixtures of PAHs and PCBs,

respectively.

Method Validation

Linear Range

For the calculation of the performance data, a calibration was carried out with

five concentration levels for PAHs and PCBs in the range of 15-500 µg/L and 1-200

µg/L, respectively. From the resulting calibration curves, the regression coefficients

were calculated, characterizing the linearity of the calibration function. Regression

coefficients were > 0.99 in both cases, indicating a good linearity of the calibration

function in these concentration ranges.

354

Figure 2: Chromatogram of the standard mixture of PAHs (25 µg/L) of each compound.

Numbering and names are according to table 1.

Figure 3: Chromatogram of the standard mixture of PCBs (200 µg/L) of each compound.

Numbering and names are according to table 2.

355

Detection Limits and Limits of Quantitaion

The limits of detection (LODs) and limits of quantitation (LOQs) were determined

for PAHs and PCBs as shown in tables 1 and 2. The calculated LODs represent the

lowest concentration levels at which the target compounds could be detected with a

signal-to-noise ratio of 3 and found to be in the range 7 - 70 ng/kg for PAHs and 149 -

330 ng/kg for PCBs. The LOQs were determined as signal-to-noise ratio of 10 and

found to be in the range from 22 - 234 ng/kg for PAHs, and 495 - 1099 ng/kg for PCBs.

LODs, LOQs and the corresponding retention times of the studied compounds are

shown in tables 1 and 2.

Table 1: Elution sequence (Peak Number), retention time, LOD and LOQ of PAHs

Peak No.

Retention time tR (min)

Standard of PAHs LOD (µg/kg)

LOQ (µg/kg)

1 7.75 1-Fluoronaphthalene (I.S) - - 2 13.98 Acenaphthylene 0.007 0.024 3 15.91 Fluorene 0.007 0.023 4 19.00 Phenanthrene 0.009 0.030 5 19.16 Anthracene 0.018 0.059 6 24.54 Pyrene 0.007 0.022 7 29.95 Benzo(a)anthracene 0.009 0.029 8 30.12 Chrysene 0.006 0.020 9 34.69 Benzo(b)fluoranthene 0.064 0.212 10 34.81 Benzo(k)fluoranthene 0.070 0.234 11 36.23 Benzo(a)pyrene 0.058 0.193 12 43.94 Indeno(1,2,3 cd)pyrene 0.022 0.075 13 44.45 Dibenzo(a,h)anthracene 0.028 0.095 14 46.06 Benzo(g,h,i)perylene 0.021 0.068

Table 2: Elution sequence (Peak Number), retention time, LOD and LOQ of PCBs

Peak No.

Retention time tR (min) Standard of PAHs LOD

(µg/kg) LOQ

(µg/kg)1 6.13 (1,8-dichloronaphthalen) IS - - 2 13.74 3,3',4,4'-Tetrachlorobiphenyl 0.153 0.510 3 14.07 3,4,4',5-Tetrachlorobiphenyl 0.154 0.513 4 14.84 2,3,3',4,4'-Pentachlorobiphenyl 0.169 0.562 5 14.93 2,3,4,4',5-Pentachlorobiphenyl 0.149 0.495 6 15.28 2,3',4,4',5-Pentachlorobiphenyl 0.162 0.541 7 15.79 2',3,4,4',5-Pentachlorobiphenyl 0.164 0.546 8 16.91 3,3',4,4',5-Pentachlorobiphenyl 0.182 0.606 9 17.57 2,3,3',4,4',5-Hexachlorobiphenyl 0.204 0.680 10 18.31 2,3,3',4,4',5'-Hexachlorobiphenyl 0.214 0.714 11 18.50 2,3',4,4',5,5'-Hexachlorobiphenyl 0.199 0.662 12 19.61 3,3',4,4',5,5'-Hexachlorobiphenyl 0.291 0.971 13 20.83 2,3,3',4,4',5,5'-Heptachlorobiphenyl 0.330 1.099

356

Extraction Recoveries

A blank sand sample from the Jordanian desert was extracted, cleaned-up and

analyzed according to the above mentioned methods. The results show the absence of

PCBs and PAHs. Five portions, each of ten grams of the above tested blank sand

sample were spiked with the PAHs standard mixture to give the concentrations of 25,

50, 100, 500 and 1000 µg/kg, and three portions, each of ten grams of the above

tested blank sand sample were spiked with the PAHs standard mixture to give the

concentrations of 50, 100 and 200 µg/kg. These samples were mixed thoroughly and

extracted, cleaned-up and analyzed according to the above mentioned methods. The

recovery tests were done in triplicate at different times. The average recoveries of

PAHs and PCBs were found between 82 -106% and 91- 114% respectively. All

recoveries were found within the acceptable range for trace analysis [17].

Instrument Precision

The precision of the instrument was measured through the injection of standard

solutions (1000, 500, 25 ng/ml for PAHs) and (200, 100, 25 ng/ml for PCBs) each

three times. The relative standard deviations, calculated as the coefficient of

variations (CV) were found to be less than the accepted limit value for trace analysis

(CV <15%), which means a good instrument precision.

Results and Discussion Concentration of PAHs in the Real Samples

The results of the studied 23 samples for the 13 PAH compounds are presented

in Tables 3 and 4 and in figure 2. It is worthy to mention that the samples 1-10 are all

taken from the surroundings of Al-Hussein Thermal Power Station, the samples 13-19

are all taken from the surroundings of the Jordan Petroleum Refinery, while the rest of

the samples (11, 12 and 20-23) were all taken from the area between the two emission

sources.

In the first sample group (1-10), the compounds which were found in relatively

high concentrations are phenanthrene ( samples 1, 4, 5,6), pyrene ( samples 4, 5 and

6), chrysene (samples 4,5,6), benzo(b)fluorenthene (samples 4, 5,6) and benzo(g,h,i)

perylene (samples 4, 5,6).

In the second sample group (13-19), the samples 17 and 18 contain the

compounds phenanthrene, pyrene and chrysene in relatively high concentrations and

the sample 19 contains all compounds in relatively high concentrations, specially

benzo(a)pyrene.

All these samples (1,4,5,6,17,18,19) are located on the west direction and

therefore these relatively high concentrations can be explained through the dominant

direction of the wind in this area which is the northeast direction [18], carrying the

pollutants to the west side of the emission sources.

The nearest sample on the west side of the petroleum refinery is sample number

19 with the highest total concentration of all 13 PAH-compounds of 190.9 µg/kg (50.7

357

µgTEQ/kg). The nearest sample on the west side of Al-Hussein power station is

sample 5 with the highest total concentration of all 13 PAH-compounds of 70.9 µg /kg

(5.7 µg TEQ/kg).

The first three samples with the highest concentrations on the west side of the

refinery are: 19, 17 (61.7 µg/kg and 2.5 µg TEQ/kg) and 18 (25.8 µg/kg and 1.5 µg

TEQ/kg).

The first three samples with the highest total concentrations on the west side of

the power station are: 5, 6 (42.9 µg/kg and 5.2 µg TEQ/kg) and 4 (30.2 µg/kg and 3.0

µg TEQ/kg).

Figure 4: Concentration profiles of PAHs in soil sample for the sites 1-23

358

Table 3: Recovery-corrected concentrations (µg/kg) of PAH and µg TEQ/kg of the

samples 1 – 12. Sample Nr.→

Comp’d ↓ 1 2 3 4 5 6 7 8 9 10 11 12

Acenaph-

thylene

0.11±

0

0.13±

0

0.17±

0.1

0.49±

0

0.57±

0

0.38±

0

0.10±

0

0.02±

0

0.02±

0

0.10±

0

0.12±

0 0.03±0

Fluorene 0.47±

0

0.58±

0

0.38±

0

0.84±

0

1.21±

0

0.88±

0.1

0.36±

0

0.12±

0

0.29±

0

0.38±

0

0.34±

0

0.28±

0

Phenan-

threne

3.47±

0.1

1.77±

0.1

1.19±

0

4.57±

0.1

11.55±

0.2

7.74±

0.6

1.46±

0

0.56±

0.2

0.69±0

.1

1.28±

0.1

1.08±

0.2 0.62± 0

Anthra-

cene

0.22±

0

0.19±

0

0.13±

0

0.42±

0

1.00±

0

0.53±

0.1

0.16±

0

0.08±

0

0.08±

0 0.15±0

0.19±

0 0.10± 0

Pyrene 0.92±

0.1

1.18±

0.1

0.51±

0

3.77±

0.1

11.70±

0.3

3.53±

0.1

1.13±

0

0.34±

0.1

0.43±

0

0.63±0

0.1

0.89±

0.1 0.36± 0

Benzo(a)

anthracene

0.34±

0

0.32±

0.1

0.10±

0

1.19±

0

2.85±

0.2

1.75±

0.2

0.43±

0

0.12±

0

0.18±

0

0.29±

0

0.63±

0.1 0.19± 0

Chrysene 1.22±

0.1

1.05±

0.2

0.39±

0

5.26±

0.1

21.78±

4

4.70±

1.0

1.79±

0

0.50±

0.1

0.58±

0

0.96±

0.1

1.89±

0.3 0.43± 0

Benzo(b)-

fluoranthene

0.70±

0.1

0.61±

0.1

0.16±

0

3.07±0

0.2

4.60±

3

4.43±

1.0

0.94±

0

0.32±

0.1

0.35±

0

0.61±

0

1.24±

0.2

0.29±

0.1

Benzo(k)-

fluoranthene

0.54±

0.1 0.51±0.1

0.16±

0

1.88±

0.2

2.31±.0

0.4

2.19±0.

0.1

0.69±

0

0.17±

0

0.23±

0

0.41±

0

0.90±

0.1

0.23±

0.1

Benzo(a)-

pyrene

0.27±

0

0.40±

0.1

0.09±

0

1.54±

0.1

3.70±

0.2

3.19±

1.0

0.50±

0.1

0.19±

0

0.26±

0.1

0.37±

0

0.79±

0.1

0.16±

0.1

Indeno(1,2,3

cd)pyrene

0.56±

0.1

0.85±

0.2

0.28±

0.1

2.75±

0.1

2.30±

0.2

4.62±1.

0

0.77±

0

0.34±

0

0.36±0

.1

0.64±

0.1

1.16±

0.2

0.32±

0.1

Dibenzo(a,h)-

anthracene

0.12±

0

0.10±

0

0.08±

0

0.45±

0

0.42±

0.03

0.60±

0.02

0.17±

0

0.10±

0

0.09±

0

0.10±

0

0.22±

0

0.12±

0.1

Benzo(g,h,i)-

perylene

0.68±

0.1

1.27±

0.3

0.46±

0.1

4.02±

0.1

6.90±

0.2

8.34±1.

1.5

1.19±

0

0.62±

0.1

0.45±

0

0.65±

0.1

1.45±

0.2

0.32±

0.2

Total

(µg/kg)

9.61±

0.3

8.94±

0.5

4.10±

0.2

30.24±

0.3

70.88±

5.1

42.88±

2.6

9.69±

0.1

3.50±

0.21

4.03±

0.2

6.56±

0.22

10.91±

0.54

3.46±

0.3

µg TEQ/kg 0.62 0.76 0.26 2.99 5.65 5.24 0.98 0.40 0.48 0.68 1.44 0.39

359

Table 4: Recovery-corrected concentrations (µg/kg) of PAH and µg TEQ/kg of

samples 13-23. Sample→

Comp’d ↓

13 14 15 16 17 18 19 20 21 22 23

Acenaph-

thylene

0.00±

0

0.02±

0

0.04±

0

0.03±

0

0.11±

0

0.15±

0.1

0.35±

0

0.05±

0

0.16±

0

0.17±

0

0.10±

0

Fluorene 0.13±

0

0.73±

0.1

0.19±

0

0.75±

0.1

1.78±

0.3

1.12±

0.1

1.61±

0.2

0.42±

0.1

0.58±

0.1

0.42±

0

0.56±

0.1

Phenan-

threne

0.23±

0

2.09±

0.1

0.49±

0.1

1.69±

0.2

8.77±

2.0

5.92±

1.0

28.02±

2.0

0.99±

0.2

1.98±

0.3

1.93±

0.2

2.22±

0.2

Anthra-

cene

0.03±

0

0.43±

0

0.11±

0

0.26±

0

2.05±

0.3

0.82±

0.1

3.88±

0.4

0.22±

0

0.32±

0

0.22±

0

0.35±

0.1

Pyrene 0.13±

0

0.58±

0.1

0.36±

0.1

0.64±

0.1

15.56±

2.0

3.20±

0.2

17.39±

1.5

0.41±

0.1

1.21±

0.2

1.33±

0.1

1.47±

0.04

Benzo(a)-

anthracene

0.05±

0

0.09±

0

0.09±

0

0.11±

0

1.87±

0.1

0.61±

0.1

14.64±

2.0

0.10±

0

0.47±

0.1

0.67±

0.1

0.90±

0.2

Chrysene 0.11±

0

0.33±

0.1

0.47±

0.1

0.55±

0.1

22.34±

2.0

6.82±

0.3

26.31±

3.0

0.17±

0

2.34±

0.3

2.20±

0.2

2.39±

0.04

Benzo(b)-

fluoranthene

0.06±

0

0.14±

0

0.21±

0

0.28±

0

2.49±

0.2

2.07±

0.1

15.38±

2.0

0.14±

0

1.43±

0.3

1.40±

0.1

1.74±

0.04

Benzo(k)-

fluoranthene

0.05±

0

0.11±

0

0.13±

0

0.22±

0

1.32±

0.1

0.98±

0

4.68±

1.0

0.08±

0

0.66±

0.1

1.28±

0.1

0.94±

0.04

Benzo(a)-

pyrene

0.04±

0

0.10±

0

0.08±

0

0.18±

0

0.72±

0.1

0.62±

0.1

31.53±

5.5

0.07±

0

0.50±

0.1

0.90±

0.1

1.14±

0.05

Indeno(1,2,3

cd)pyrene

0.04±

0

0.12±

0

0.21±

0

0.42±

0.1

1.80±

0.3

1.43±

0.2 12.21±4.5

0.15±

0

0.96±

0.2

1.27±

0.1

1.57±

0.3

Dibenzo(a,h)-

anthracene

0.01±

0

0.00±

0

0.05±

0

0.13±

0

0.70±

0.1

0.24±

0

13.95±

4.0

0.05±

0

0.20±

0

0.19±

0

0.27±

0

Benzo(g,h,i)-

perylene

0.05±

0

0.17±

0

0.30±

0.1

0.46±

0.1

2.16±

0.3 1.77±0.2

20.90±

6.0

0.09±

0

1.22±

0.2 1.19±0.2

1.28±

0.3

Total

(µg/kg)

0.94±

0

4.93±

0.2

2.73±

0.2

5.72±

0.3

61.67±

3.5

25.75±

1.1

190.86±

11.3

2.92±

0.3

12.01±

0.66

13.18±

0.4

13.18±

0.54

µg TEQ/kg 0.79 0.17 0.20 0.43 2.46 1.48 50.73 0.17 1.09 1.59 1.59

Comparing the total concentrations of the PAHs in the studied samples from all

sites with other regions, we find that the concentration range in the present study (0.94

– 190.86 µg/kg) is much lower than those found in soil samples after long term

irrigation with wastewater in Shenyang, China, which was (950 – 2790 µg/kg) [19]. Soil

samples taken from the vicinity of Pincher Creek refinery in Alberta/Canada found to

contain a total concentration of PAHs of 9810 mg/kg [20]. According to the WHO [21], the

total PAHs level in unpolluted areas was 5-100 µg/kg soil. These facts show that the

pollution in the studied area is very low.

360

Toxicity Equivalents of the Samples

The benzo(a)pyrene-toxicity equivalents (B(a)P-TEQ) were calculated using

the B(a)P toxic equivalency factors (TEF) recommended for use by the US EPA [22] as

shown in table 5 and the results are presented in tables 3 and 4.

Table 5: Benzo (a)pyrene Toxic Equivalency Factors (BAP-TEF)[24] Compound EPA-TEF

Benzo(a)pyrene 1.0

Benz(a)anthracene 0.1

Benzo(b)fluoranthene 0.1

Benzo(k)fluoranthen 0.1

Chrysene 0.001

Dibenzo(a,h)anthracene 1.0

Indeno(1,2,3-c,d)pyrene 0.1

For the total concentrations of all 13 studied PAH-compounds, one can predict

from tables 3 and 4 that the five sites with the highest total concentrations have the

following ascending order: 19 >5 >17 > 6>18. For both TEQs and the total cancer risk,

also the same four sites show the highest values but in the following order: 19 >5 >6

>17>18.

Concentrations of PCBs in the Real Samples

It is also clear that our samples did not contain any concentration of the studied

PCBs mixture. This could be explained that PCBs need harder conditions to be

synthesized which are the presence of organic or inorganic chloride and a metal

catalyst. But our results are reasonable compared to those of the soil samples after

long period of wastewater irrigation from Shenyang, China [23] where they found PCBs

in the range of 4.4 – 20.14 µg/kg. While another surface soil samples from the

industrialized and urban area of KwaZulu-Natal, South Africa show a concentration

range of (1 – 10 µg/kg) [24], and in a more industrialized city like Moscow the range of

PCBs was 3.1– 42 µg/kg [25].

Cancer Risk Assessment

The values of total estimated cancer risk of the samples used to draw figure 3

were calculated using the Incremental Life Cancer Risk (ILCR) equation given in [26].

The highest total estimated cancer risk was found in soil sample 19. In

comparison, while the lowest total estimated cancer risk was found in soil sample 13,

as shown in figure 3. According to USEPA guidelines in regulatory terms, an estimated

cancer risk of 10-6 or less denotes virtual safety and an estimated cancer risk of greater

than 10-4 denotes potentially high risk. The estimated cancer risks under normal

exposures to soil samples-PAHs for all age groups in most of locations are equal or

less than 10-6. Under worst-case scenario, no estimated cancer risks of the extreme

exposures exceeded 10-4. By multiplying the estimated cancer risks of exposing to soil

361

sample-PAHs by 106, it is possible to determine the theoretical number of cancer

cases per million of people. For example (5.53 × 10-6), this means that the number of

people who are suspected of cancer due to exposure to soil sample-PAHs in the site

19 is six out of every million. In other words if a person was exposed to the highest

level of PAHs - TEQ in the site 19 for 70 years, he has 5 in million increased risk of

cancer from this exposure, this is the highest estimate of the risk and the actual risk is

likely lower.

Figure 5: The total estimated cancer risks of exposing to PAHs of the soil samples 1 -

23 through different exposure pathway

362

Concluding Remarks These findings show that the studied two industrial facilities did not cause high

level of organic pollution. The analyzed 23 samples did not contain any of the studied

13 compounds of PCBs and very low level of pollution with PAHs, but in measurable

concentrations.

The results show that the PAH-compounds found in relatively high

concentrations are: phenanthrene, pyrene, chrysene, benzo(b)fluorenthene and

benzo(g,h,i)perylene. Benzo(a)pyrene was found only in two samples (5 and 19) with

relatively high concentration.

The results show also that the samples with relatively high concentrations of

total PAH-compounds are located in the west side of the emission sources which

means that the northeast wind carry the pollutants from the emitting sources to the

west.

The results show that the petroleum refinery cause more pollution than the

power station and the sample with the highest TEQ-value (sample 19) is taken from

the vicinity (west side) of the refinery. This sample contains the highest concentration

of the carcinogenic compound benzo(a)pyrene ( 31.5 µg/kg).

The estimated cancer risk was acceptable compared to the USEPA guidelines

and the overall environmental situation in the surroundings of the two facilities is also

acceptable.

Abbreviations RSD = Relative standard deviation

TEQ = Toxicity equivalent

TEF = Toxic equivalency factor

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