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Polycyclic Aromatic Hydrocarbons (PAHs) in Sediment Samples From Euphrates River,Iraq
Hamid T .Al-Saad* Shaimaa T .Abed Ali** ; **Bassim Y. AlKafaji and Sliah Mahdi*
** Department of Biology,College of Sciences, University of Thi-Qar ,Iraq.
*Department of Marine Chemistry, Marine Sciences Center University of Basrah, Iraq
* Corresponding author email: htalsaad@yahoo.com
Abstract
Sediment samples were collected from four selected sites along the Euphrates river near Al-Nassyira city south of Iraq during summer2012 to winter 2013 .sixteen PAHs listed by USEPA as priority pollutants were detected .The total of PAHs was ranged from 0.197 ng/g dry weight in summer at station 1 to 80.006 ng/g dry weight in winter at station 3. The LMW/HMW, Flouranthene/Pyrene and Phenanthrene /Anthracene ratio indicated that the source of PAHs was pyrogenic Whereas BaA/(BaA+Chry) ratio indicated that the source of PAHs was pyrogenic and at least petrognic. the highest value TOC % were 1.91% at station 3 in winter while the lowest value were 0.73% at station 1 in summer. the study shows that there is a significant correlations between TOC% ,grain size in the sed-iment with concentration of PAH . The present study indicated that hydrocarbons exist in the study area, but its levels were in acceptable range.
Key words: PAHs .sediment, Euphrates River, pollution
Introduction
Monitoring of some Polycyclic Aromatic Hydrocarbons (PAHs) compounds in the sedi-ments give a good information about their concentration ,origin and distribution in the aquatic system. Polycyclic Aromatic Hydrocarbons (PAHs) with two to six rings are a class of organic contaminants mainly derived from incomplete combustion of organic matter ,such as coal ,fossil, fuel (M.B et aL., 2012) such as Phenanthrene ,Fluorine , benzo [a]pyrene and pyrene as in car exhaust ,while Phenanthrene ,fluorine , and pyrine as in die-sel vehicles exhaust(Azhai et al .,2011 ; Al-Hejuje et al .,2015 ) .Numerous of these com-pounds are Potential carcinogens (Al-saad ,1995) Study of the composition of hydrocarbon compounds in different marine sediments can provide much information about their sources and diagenetic processes and reflect the extent of anthropogenic pressures on the environment (Hostetter et al ., 1999; Medeiros et al ., 2005). Hydrocarbons generated by biological or diagenetic processes natural hydrocarbon baseline of an ecosystem (com-mendatore and esteves, 2004).Human activities like shipping and industrial ,stromwater and domestic discharge are believed to be an important influence on hydrocarbons in aquat-ic sediment especially in coastal areas (Zheng and Richardson,1999;Commendatore and Esteves,2004) Ratio of LMW/HMW ,Phenanthrene /Anthracene, Flouranthene/ Pyrene and some index to give an image about the sources of hydrocarbons compounds in the aquatic environments .
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Study Area
The study area included 4 stations on Euphrates river in Al-Nassiryia city, the first station located at the entrance of the river to Al-Nassiryia city and far from the second station by 10 km which located at convergence (junction) zone of hot water emerging from the ther-mal electric power station with the river. The third station located at convergence zone stream discharge waste water, while the fourth station located before the river leaving the city of Al-Nassiryia and far from the third station by 10 km. Fig.(1)
Materials and Methods
Samples were collected from the above mentioned stations during summer 2012 to winter 2013 Sediment was collected by means of Veen grab sampler. In lab sediment samples were dried in freeze dryer, grind finely in agate mortar and sieved through a 63 M'' mesh metal sieve. Stored in glasses containers until analysis .fifty grams of sieved sediments were place in cellulose thimble and soxhlet extracted according to method of (Goutx and Saliot ,1980) the sample was then analyzed in a Allegent capillary gas chromatography (GC) in which the helium gas was used as a carrier gas with a linear velocity of 1.5 ml minutes'1. The operating temperatures for detector and injector were 350''C and 320''C, respectively. The silica capillary column was operated under initial, final and rate tempera-tures that programmed as follows: Initial temperature was 60''C for 4 min while final tem-perature was 280''C for 30 min and rate was 4''C/ minutes.
Fig.1: sample station
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Total organic carbon TOC concentration in sediment were determined according to burning method (Ball,1964).
Tow grams of sediments dried and( sieved <63 mm) were put in pre-weighted crucible and burned at 550C for 48 hrs. the difference in mass of crucible and sediment sample before and after burning was calculated as TOC. Meam grain size analysis of the sediment was carried out using the combined dry sieve and pipet techniques according to Folk (1974) method. The grain size (silt ,sand and clay )was determined as percentage of sediments.
Compounds Winter S1 S2 S3 S4
Naphthalene
0.010
4.046
5.257
0.320
Indole
0.040
3.210
4.220
0.260
Acenaphthylene
0.003
2.363
3.010
0.020
Acanaphthene
0.020
1.350
2.260
0.035
fluorine
0.008
3.327
4.406
0.012
Phenanthrene
0.028
2.674
3.546
0.036
Anthracene
0.043
2.093
5.586
0.053
Fluoronthene
0.043
4.231
4.140
0.350
Pyrene
0.035
4.301
5.241
0.042
Carbazol
0.039
5.563
7.123
0.041
Benz(a)anthracene
0.026
3.408
6.083
0.027
Chrysene
0.007
3.238
4.627
0.042
B(b) fluoronthene
0.004
2.298
4.547
0.040
B(k) fluoronthene
0.031
2.825
3.547
0.033
Benzo(a)pyrene
0.041
3.537
5.773
0.109
indeno(1,2,3-cd)pyrene
0.003
2.652
3.039
0.110
dibenzo(a,h)anthracene
0.010
4.267
4.039
0.160
benzo(g,h,i)perylene
0.002
2.963
3.562
0.006
Total
0.393
58.346
80.006
1.696
fluoranthen/pyren
1.229
0.984
0.790
8.333
Phen/Ant
0.651
1.278
0.635
0.679
LMW-PAHs/HMW-PAHs
0.631
0.485
0.547
0.767
Ant/(Ant+Phen)
0.606
0.439
0.612
0.596
BaA/(BaA+Chry)
0.854
0.522
0.555
0.722
Flt/(Flt+py)
0.551
0.496
0.441
0.893
InP/(InP+BghiP)
0.231
0.383
0.429
0.407
Table (1) Concentration of PAHs compounds in stations during winter 2013
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Naph 7%
Ind 6%
Acey 4%
Acanap 3%
flu 6%
Phena 4%
Anthr 6%
Fluorant 6%
Pyr 7%
Carb 9%
B(a)anth 7%
Chry 6%
B(b) flu 5%
B(k) flu 5%
B(a)py 7%
i(1,2,3-cd)py 4%
di(a,h)anthr 6%
be(g,h,i)per 5%
Fig. 2: The PAHs compounds percentage in sediments samples during the studied periods.
Fig.3. Total of PAHs in stations during winter 2013
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Compounds summer S1 S2 S3 S4
Naphthalene
0.005
2.023
2.629
0.160
Indole
0.020
1.605
2.110
0.130
Acenaphthylene
0.002
1.182
1.505
0.010
Acanaphthene
0.010
0.675
1.130
0.018
fluorine
0.004
1.664
2.203
0.006
Phenanthrene
0.014
1.337
1.773
0.018
Anthracene
0.022
1.047
2.793
0.027
Fluoronthene
0.022
2.116
2.070
0.175
Pyrene
0.018
2.151
2.621
0.021
Carbazol
0.020
2.782
3.562
0.021
Benz(a)anthracene
0.013
1.704
3.042
0.014
Chrysene
0.004
1.619
2.314
0.021
B(b) fluoronthene
0.002
1.149
2.274
0.020
B(k) fluoronthene
0.016
1.413
1.774
0.017
Benzo(a)pyrene
0.021
1.769
2.887
0.055
indeno(1,2,3-cd)pyrene
0.002
1.326
1.520
0.055
dibenzo(a,h)anthracene
0.005
2.134
2.020
0.080
benzo(g,h,i)perylene
0.001
1.482
1.781
0.003
Total
0.197
29.173
40.003
0.848
fluoranthen/pyren
1.229
0.984
0.790
8.333
Phen/Ant
0.651
1.278
0.635
0.679
LMW-PAHs/HMW-PAHs
0.631
0.485
0.547
0.767
Ant/(Ant+Phen)
0.606
0.439
0.612
0.596
BaA/(BaA+Chry)
0.854
0.522
0.555
0.722
Flt/(Flt+py)
0.551
0.496
0.441
0.893
InP/(InP+BghiP)
0.231
0.383
0.429
0.407
BaA/(BaA+Chry)
0.854
0.522
0.555
0.722
Flt/(Flt+py)
0.551
0.496
0.441
0.893
InP/(InP+BghiP)
0.231
0.383
0.429
0.407
Table (2) Concentration of PAHs in sediment in summer 2012
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Fig. 5: The PAHs compounds percentage in sediments samples during the studied periods.
Fig.6 Total of PAHs stations during summer 2012
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winter S.D mean Range Station
0.04
0.92
0.79-0.88
S1
0.02
1.85
1.82-1.87
S2
0.03
1.91
1.89-1.95
S3
0.01
1.56
1.55-1.58
S4
LSD (0.05) 0.06 Summer
0.04
0.73
0.69-0.78
S1
0.38
1.58
1.29-136
S2
0.02
1.7
1.68-1.72
S3
0.05
1.33
1.50-1.60
S4 LSD (0.05) 0.06
Table (3) TOC% in sediment samples
Fig.7. percentage of sediment texture in study area
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Results and discussion
All sample were anylazed for 16 USEPA priority PAHs,including naphthalene (NaP), acenaphthene(Ace), acenaphthylene (Any),fluorine (Fl),phenanthrene (Phe), anthra-cene(An),fluoranthene (Fla), pyrene (Pyr), benz[a]anthracene (BaA), chrysene(Chr), benzo [b]fluoranthene (BbF) , benzo [K]fluoranthene (BKF), benzo [a] pyrene(BaP) ,indeno [1,2,3p-cd]pyrene (IcdP),dibenz[a,h]anthracene (dBA), and benzo [g,h,i]perylene (BPe),also measured and quantified according to the respective peak areas. The sources of PAHs to aquatic sediment is pyrogenic from combustion processes and small contribution of petrogenic source and enter the sediments from runoff and atmospheric deposition (Chen, 2001). The lowest value of (0.001ng/ g) dry weight was recorded for benzo (g,h, i) perylene in summer while the highest value of (7.123 ng/ g) dry weight for Carbazol in winter (Table 1,2) .some individual PAHs showed significant differences among sites. It was found that variation in the concentrations of PAHs among sites may be due to addi-tional input source (Maskaoui et al ., 2002) and the proximity of site from the source. .the highest concentration recorded were obtained in winter ( 7.123 ng/ g) dry weight while the lowest concentration recorded in summer were( 0.001 ng/ g) dry weight. This may be relat-ed with the climatic condition of Iraq and the effect of photo oxidation ,volatilization and high degradation during the hot season (Al-Saad, 1987;Al- Hamdi, 1989; and AlTimari , 2000).the highest concentrations were recorded at station 3and 2 due to effluents dis-charged from domestic sewage treatment unit and electric power station which are located at the river bank. Although the high concentrations of PAHs in sediment ,but it lie within acceptable range .the highest concentration of total PAHs were 80.006 ng/ g dry weight at station 3 in winter .the lowest concentration of total PAHs were 0.197 ng/ g dry weight at station 1 in summer . the highest value TOC % were 1.91% at station 3 in winter while the lowest value were 0.73% at station 1 in summer (Table3). the present results referred to significant positive correlation between TOC% and total PAHs in the sediment (r=0.81,P<0.01) which may be due to hydrophobicity nature of PAHs and their affinity to organic material or due to the fraction of TOC in the sediment (Al-saad -1983;Zakaria et al., 2002; Maskaoui et al., 2002). the sediment texture were mixed from (sand ,clay,and silt) where value was (22.4%,86.4%,9.3%) at station 1 while (6.58% ,80.2%,10.2%) at sta-tion 2 while (5.71%,77.03%,17.25%)at station 3 and (2.33%,26.05%,71.61%)at station 4 respectively (Fig.7)
In the present study ,the mean ratio of Phen /Ant ,Flur/Py ,and LMW-PAHs/HMW-PAHs can provide a useful information for explanation of the origin of PAHs in the sediment .the mean ratio of Phen/Ant(0.651,1.278 , ,0.635,0.679) at station 1,2 ,3,4 in winter respective-ly Phen/Ant<10 refer to pyrogenic Flur/py(1.229, ,8.333)at station 1,4 respectively Flur/py >1 refer to pyrogenic while (0.984,0.790)at station 2,3 respectively refer to petrognic products runoff, effluents discharged from domestic sewage treatment unit and electric power. The results prove the sources pyrogenic and least petrognic.as a conclusion the ra-tios of (Flouranthene/pyrene ,Phenanthrene/Anthracene ,Benzo(a)pyrene /Benzo(ghi)perylene and LMW-PAHs /HMW-PAHs, refer to origin from different sources including pyrogenic , petrognic and urban air. The total higher concentration PAHs was at station 3,2 in winter while the lowest concentration PAHs at station 1,4 in summer.
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Strong correlation was recorded for PAHs in sediment with TOC% due to affinity to organ-ic materials
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