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Department of Biology, Jahrom Branch, Islamic Azad University, Jahrom, Iran. 1. Department of ..... species of the aquatic food web of Rang sit agricultural area ...
Middle-East Journal of Scientific Research 10 (1): 01-07, 2011 ISSN 1990-9233 © IDOSI Publications, 2011

Determination of Polycyclic Aromatic Hydrocarbons (PAHs) in Water and Sediments of the Kor River, Iran 1

Farshid Kafilzadeh, 1Amir Houshang Shiva and 2Rokhsareh Malekpour

Department of Biology, Jahrom Branch, Islamic Azad University, Jahrom, Iran Department of Biology, Kazeroun Branch, Islamic Azad University, Kazeroun, Iran 1

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Abstract: Distribution of the sixteen polycyclic aromatic hydrocarbons (PAHs) was studied in surface water and sediment of Kor River. Liquid-liquid extraction was used for water samples, while PAHs in sediments were extracted using Soxhlet Extraction and finally analyzed by means of gas chromatography. Results showed that in water samples, the highest concentration was related to acenaphthene (3-ring PAH), whereas fluoranthene (4-ring PAH) was the most important pollutant in sediments. In both water and sediment samples, the highest and the lowest mean concentrations of PAHs were observed in autumn and summer, respectively. Ratios of specific PAH compound including Phenantharene/Anthracene and Fluoranthene/Pyrene were calculated to evaluate the possible sources of PAHs contamination. These ratios reflect a pyrolytic origin of PAHs for sediments, as well as a pyrolytic or pyrogenic origin for water samples (with a dominant pyrolytic input) in the study area. Key words:Polycyclic Aromatic Hydrocarbons (PAHs) Kor River INTRODUCTION

Gas Chromatograph

Pyrolytic

Petrogenic

The PAH composition within the sediments reflects the source(s) from which the PAHs were derived [5, 6]. Larger concentrations of lower molecular weight PAHs (e.g. acenaphthene and fluorene) most often occur in sample matrices contaminated with naturally occurring (petrogenic) PAHs. PAHs originating from combustion (pyrolytic) sources often contain elevated concentrations of higher molecular weight and higher membered-ring PAHs (e.g. phenanthrene, fluoranthene, pyrene) and fewer low molecular weight PAHs [7]. These hydrocarbons can become dangerous especially if they come into the alimentary chain, since some of the higher PAHs and their metabolites, can form DNA adducts which can induce mutations. Because of their carcinogenic and mutagenic properties the USEPA classified 16 of them as priority pollutants. Some authors suggested that PAHs can be synthesized by unicellular algae, higher plants or bacteria but at the same time others concluded that organisms accumulate PAHs rather than synthesize them [8]. Kor River is the most important river in Fars province, Southern Iran which originates from Northwest heights of Eghlid and pours in Bakhtegan Lake after joining with Sivand River. Kor River provides drinking water for the

Polycyclic aromatic hydrocarbons (PAHs) represent a wide spread class of environmental chemical pollutants and are ubiquitous contaminants with two or more fused aromatic rings in marine environments. PAHs’ solubility in water decreases, while correspondingly their boiling and melting point increases, with increasing molecular weight [1]. PAHs are lipophilic compounds with very low water solubility and therefore, their concentration in water is very low [2, 3]. As a consequence of their hydrophobic nature, PAHs in aquatic environments rapidly tend to become associated to the particulate matter ending in sedimentation. Therefore, sediments represent the most important reservoir of PAHs in the marine environment. For that reason, PAHs accumulation in coastal sediments is both due to anthropogenic and natural emissions. Among anthropogenic factors, petrogenic and pyrolytic sources are the most important. Whereas pyrolytic sources include combustion processes (e.g., fossil fuel combustion, forest fires, shrub and grass fires), the petrogenic input is closely related to petroleum products (e.g., oil spills, road construction materials) [3, 4].

Corresponding Author: Farshid Kafilzadeh, Department of Biology, Jahrom Branch, Islamic Azad University, Jahrom, Iran.

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Middle-East J. Sci. Res., 10 (1): 01-07, 2011

residents of Shiraz and Marvdasht as well as suburbs so that thousands of local farmers are related to this river thoroughly [9]. This ecosystem during the years, due to its closeness to the town and to the richness of human activities (e.g. industrial, aquaculture and urban activities) have accumulated in sediments both high PAHs and organic matter levels, so the goal of this work is to study the distribution of the sixteen PAHs in water and sediments of Kor River through four seasons and determination of their source(s) on the basis of their concentrations.

caps and were immediately transported to the laboratory for analysis. Sediment samples (about 2 kg each) were taken from the same locations and time for water sampling at a depth 5 cm of sediment surface and then transferred to the laboratory. Samples were air dried in dark for 48 hours before analysis. In the laboratory, using liquid-liquid extraction (LLE) as described in APHA [10], the total amount of each surface water sample (800 ml) was filtered with Whatman filter paper (i.d. 70 mm) to remove debris and suspended materials and then poured into a 2 liter separatory funnel. For the first LLE, the mixture of 100 ml n-hexane and dichloromethane (1:1 v/v) was added and shaken vigorously for 2 min before two phase separation. The water-phase was drained from the separatory funnel into a 1000 ml beaker. The organic-phase was carefully poured into a glass funnel containing 20 g of anhydrous sodium sulfate. Following the second and third LLE, the water-phase was poured back into the separatory funnel to re-extract with 50 ml of the same solvent mixture. The extract was concentrated to the volume of 2 ml under a gentle stream of nitrogen using rotary evaporator and then analyzed with Gas Chromatograph [11].

MATERIALS AND METHODS Water and sediment samples were collected seasonally during the period from April 2010 to March 2011 from four stations namely Petrochemical bridge, Khan bridge, Doo Shakh bridge and Entrance of Bakhtegan Lake which are shown on the map (Fig. 1). Each sampling was carried out in five replicates. Water samples (2.5 L) were collected in glass bottles at the water surface and 50 cm below water level from the four different sites. The bottles were covered with screw

Fig. 1: The map of four sampling stations in Kor River 2

Middle-East J. Sci. Res., 10 (1): 01-07, 2011

Air-dried sediments were sieved (mesh size 500 µm) and homogenized in mortar. PAHs in sediments were extracted using Soxhlet Extraction. A 10 g homogenized sample was extracted with 250 ml of dichloromethane for 16 h and concentrated to 2 ml using vacuum rotary evaporator [12]. Clean up and separation of water and sediments was achieved through chromatography with a silica/alumina column. Saturated aliphatic hydrocarbons were eluted with 20 ml of n-hexane and then aromatic hydrocarbons were eluted with 30 ml of a mixture of hexane and dichloromethane (90:10) (v/v). The volume of the eluted fraction was reduced to 1 ml and then the aromatic hydrocarbon fraction was injected into a gas liquid chromatography equipped with a flam ionization detector (GC/FID) [2]. GC analysis was conducted on a fused silica capillary column of 60 m length, 0.25 mm id and 0.5 µm film thicknesses to detect 16 PAH components. The following PAHs were used for quantitation: naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene, benzo [a] anthracene, benzo [b] fluoranthene, benzo [k] fluoranthene, benzo [a] pyrene, dibenzo [a,h] anthracene, benzo [g,h,i] perylene, Indeno [1,2,3-cd] pyrene. Recoveries were carried out by the addition of PAHs standards mixture at the three levels of 1, 5 and 10 µg. The overall mean of recovery percentages were found to be 96.80% and 91.26% for water and sediment samples, respectively. All data were corrected according to the recovery percentage values.

Statistical analyses were carried out by analysis of variance (ANOVA) using SPSS 15 software. Mean values were analyzed by the Duncan’s test. RESULTS AND DISCUSSION The concentrations of the 16 detected polycyclic aromatic hydrocarbons (PAHs) in surface water and sediments of Kor River are shown on Tables 1 and 2. In terms of individual PAH composition in water and sediments, most compounds analyzed were detected at all location site. As can be seen in water samples, the highest concentration was related to acenaphthene (3-ring PAH), which the mean value (ng L 1) in four sites was 15.11, 20.19, 44.27 and 65.72, respectively. ANOVA and Duncan tests showed a significant difference between mean concentration of acenaphthene and other detected PAHs (P 0.01). At the same time, the lowest concentration of PAH components in water samples of Kor River was related to Indeno [1,2,3-cd] pyrene. The associated mean values (ng L 1) were 0.3, 0.51, 0.8 and 0.91. According to our results, the concentration of low molecular weight (2-3 ring) polycyclic aromatic hydrocarbons (LPAHs) in water samples of Kor River is higher than high molecular weight (4-6 ring) PAHs (HPAHs) (Fig. 2A). The mean values of total concentration (mg L 1) of LPAHs and HPAHs in four sampling sites were 117.15 and 26.83 respectively, which are significantly different (P 0.01).

Table 1: Concentrations of PAHs (ng L 1) in surface water of the Kor River

Components

Station 1 ------------------------------------Mean Range

Station 2 ----------------------------------Mean Range

Station 3 ----------------------------------Mean Range

Station 4 ------------------------------------Mean Range

Naphthalene 7.13 Acenaphthylene 6.02 Acenaphthene 15.11 Fluorene 3.16 Phenanthrene 6.11 Anthracene 4.95 Total LPAH 42.48 Fluoranthene 0.91 Pyrene 0.78 Chrysene 0.75 Benzo[a]anthracene 1.34 Benzo[b]fluoranthene 0.98 Benzo[k]fluoranthene 1.27 Benzo[a]pyrene 1.49 Dibenzo[a,h]anthracene 0.60 Benzo[g,h,I]perylene 0.52 Indeno[1,2,3-cd]pyrene 0.30 Total HPAH 8.94

5.1-10.1 4.7-9.3 16.4-22.3 2.9-4.2 5.2-8.3 3.9-6.5 38.3-60.7 0.8-1.3 0.7-1.2 0.7-1.1 1.1-2.4 0.7-1.4 0.9-1.8 1.1-2.0 0.4-1.1 0.4-0.8 0.2-0.6 7.1-13.7

11.18 9.81 20.19 4.12 8.11 6.16 59.57 1.42 1.66 2.40 2.42 1.50 1.36 1.22 1.10 2.15 0.51 15.74

6.2-14.2 7.1-14.2 16.4-26.4 2.9-6.3 6.2-12.2 5.1-9.4 44.0-82.7 1.1-2.2 1.2-2.9 1.9-3.5 2.2-3.3 1.1-2.6 1.1-2.7 0.8-2.5 0.7-1.9 1.6-3.2 0.4-0.7 12.2-25.8

10.16 18.43 44.27 9.81 14.66 31.43 128.7 3.14 3.58 4.12 3.33 3.95 1.92 4.13 1.52 2.57 0.80 29.06

6.5-14.6 14.7-27.2 36.7-58.4 7.2-13.4 10.6-17.2 26.8-43.1 102.5-174.1 2.7-5.3 2.9-4.9 3.3-6.9 2.8-5.5 3.1-5.1 1.4-3.7 3.1-5.2 1.1-3.8 1.6-5.9 0.6-1.3 22.5-47.7

49.50 40.41 65.72 18.60 31.43 32.15 237.8 7.75 4.09 7.24 7.55 6.17 2.66 7.18 3.19 6.84 0.91 53.58

37.4-56.1 39.5-46.1 51.5-73.3 13.4-27.3 25.0-43.1 24.4-42.2 191.3-288.1 5.8-12.2 3.1-7.3 5.9-11.5 6.1-13.0 5.4-9.1 2.2-3.9 5.9-10.1 2.3-6.3 5.9-11.8 0.6-1.7 43.4-87.0

Total

45.4-74.5

75.31

56.2 -108.5

157.8

125.1-221.8

291.4

234.7-375.1

51.42

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Middle-East J. Sci. Res., 10 (1): 01-07, 2011 Table 2: Concentrations of PAHs (ng g 1) in surface sediment of the Kor River Station 1 ---------------------------------Mean Range

Components

Station 2 -------------------------------Mean Range

Station 3 ----------------------------------Mean Range

Station 4 -----------------------------------Mean Range

Naphthalene 10.88 Acenaphthylene 7.57 Acenaphthene 7.77 Fluorene 5.51 Phenanthrene 5.81 Anthracene 8.36 Total LPAH 45.90 Fluoranthene 26.33 Pyrene 23.37 Chrysene 20.52 Benzo[a]anthracene 24.22 Benzo[b]fluoranthene 15.22 Benzo[k]fluoranthene 9.55 Benzo[a]pyrene 15.04 Dibenzo[a,h]anthracene 22.13 Benzo[g,h,I]perylene 25.77 Indeno[1,2,3-cd]pyrene 4.29 Total HPAH 186.4

8.4-14.5 5.9-12.3 6.2-11.2 4.8-7.1 4.2-8.7 6.9-11.1 36.5-65.1 16.5-40.5 15.2-32.6 14.4-31.5 19.2-35.1 11.7-21.6 6.3-14.9 10.5-24.3 15.2-33.2 19.7-31.1 2.2-7.8 130.8-272.8

11.50 7.41 9.61 6.42 6.28 7.91 49.13 51.12 24.24 24.27 36.18 18.27 8.41 17.55 25.96 25.50 5.33 236.8

7.5-16.7 6.2-12.7 7.3-12.2 5.0-8.5 5.1-8.3 6.5-11.1 37.7-69.6 39.5-79.2 18.1-38.5 17.3-38.9 30.1-37.1 13.4-25.8 5.9-12.2 12.5-26.5 20.4-35.9 19.6-33.1 3.7-8.8 180.6-336.3

12.53 10.50 9.23 7.44 6.18 8.12 54.0 66.57 26.88 21.12 35.84 19.66 16.16 19.48 27.98 28.96 5.22 267.9

9.2-17.7 8.7-15.1 7.7-14.4 6.4-9.2 5.4-9.7 6.3-12.9 43.8-79.1 49.9-90.5 19.7-42.5 15.7-39.5 27.3-38.7 14.8-28.5 12.6-24.2 15.5-28.3 20.4-36.2 20.3-36.3 2.8-8.7 199.1-373.7

12.15 16.27 12.46 8.52 8.77 11.38 69.55 64.14 36.18 26.28 38.86 24.84 40.58 31.84 24.16 29.78 9.91 326.6

8.4-18.2 11.3-21.6 8.5-16.2 6.3-12.7 5.4-10.2 6.7-14.2 46.7-93.1 46.5-91.3 28.2-54.1 18.8-44.2 29.6-43.0 17.7-33.9 30.3-47.2 24.4-35.5 16.2-40.5 22.5-37.5 5.4-11.7 239.7-437.2

Total

167.4-337.9

285.9

218.3-405.9

321.9

242.9-452.8

396.1

286.4-530.3

232.3

A 4-rings

5-rings

6-rings

B 2-rings

6-rings

2-rings

3-rings

5-rings 3-rings 4-rings

Fig. 2: The percentage of mean concentration of 2-rings, 3-rings, 4-rings, 5-rings and 6-rings PAHs in water (A) and sediment (B) samples of Kor River stations As far as the sediment samples are concerned, fluoranthene (4-ring PAH) was the most important pollutant with mean concentrations (ng g 1) of 26.33, 51.12, 66.57, 64.14 in four stations, respectively. The difference between fluoranthene and other PAHs concentration was highly significant (P 0.01). Meanwhile, in terms of the lowest concentration, fluorene (3-ring PAH) ranked the first position, followed by phenanthrene (3-ring PAH). The respective Figures (ng g 1) in four stations are 5.51, 6.42, 7.44, 8.52 for fluorene and 5.81, 6.28, 6.18, 8.77 for phenanthrene. Contrary to observed compositions of PAHs in surface water, HPAHs are more dominant in the sediments of Kor River rather than LPAHs (Fig. 2B). The mean total concentration values (ng g 1) were 254.43 for the former

and 54.64 for the latter which are significantly different (P 0.01). According to Nasr et al. [2], Mohammed et al. [13] and Koh et al. [14], the composition pattern of PAH in sediments is mostly dominated by four-ring PAHs, while water samples are dominated by three-ring PAHs. The difference in contaminant abundance by different PAH may be attributed to molecular weight and bacterial degradation. A wide array of microorganisms including fungi, algae and bacteria are known to degrade PAHs. However, bacteria play by far the most important role in complete mineralization. Lower molecular weight PAHs such as naphthalene and phenanthrene are degraded rapidly in sediments, but higher molecular weight PAHs such as pyrene, fluoranthene, 4

Middle-East J. Sci. Res., 10 (1): 01-07, 2011

Fig. 3: Comparison the mean concentration of PAHs in water samples among different seasons

Fig. 4: Comparison the mean concentration of PAHs in sediment samples among different seasons

benzo[a]anthracene and benzo[a]pyrene are more recalcitrant [15]. Those PAHs that can survive the down column transport will reach the sediment bed, such PAHs are quite likely to be of a relatively high molecular weight with high ring numbers and hence more resistant to degradation processes. The degree of sorption in aquatic systems of hydrophobic PAHs contaminants is often related to a compounds octanol/water partition coefficient (Kow) too [16]. Therefore, the solubility of polycyclic aromatic hydrocarbons decreases as the Kow and molecular weight increase. As a consequence, the heavier molecular weight compounds with higher Kow favour association with inorganic and organic suspended particles and will settle in sediments. The present results referred to significant differences in the concentrations of PAHs in water and sediment samples among seasons (P10, whereas combustion processes often result in low Ph/An ratios (