Source identification of polycyclic aromatic hydrocarbons (PAHs) in sediment samples from the northern part of the Persian Gulf, Iran Roozbeh Mirza, Mehdi Mohammadi, Iraj Faghiri, Ehsan Abedi, Ali Fakhri, Ali Azimi & Mohammad Ali Zahed Environmental Monitoring and Assessment An International Journal Devoted to Progress in the Use of Monitoring Data in Assessing Environmental Risks to Man and the Environment ISSN 0167-6369 Volume 186 Number 11 Environ Monit Assess (2014) 186:7387-7398 DOI 10.1007/s10661-014-3935-y
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Author's personal copy Environ Monit Assess (2014) 186:7387–7398 DOI 10.1007/s10661-014-3935-y
Source identification of polycyclic aromatic hydrocarbons (PAHs) in sediment samples from the northern part of the Persian Gulf, Iran Roozbeh Mirza & Mehdi Mohammadi & Iraj Faghiri & Ehsan Abedi & Ali Fakhri & Ali Azimi & Mohammad Ali Zahed
Received: 17 December 2013 / Accepted: 7 July 2014 / Published online: 15 July 2014 # Springer International Publishing Switzerland 2014
Abstract Samples of surface sediments from the Iranian coast of the Persian Gulf were examined to determine the levels and sources of 15 polycyclic aromatic hydrocarbons (PAHs). Samples were collected from 30 sampling sites and analyzed for PAHs by gas chromatography–mass spectrometry (GC-MS). Total concentrations of PAHs ranged from 93 to 4,077 ng g−1 dry weight. The PAH composition from 30 sampling sites was dominated by four-ring PAH compounds. Molecular indices based on the ratios of PAH concentrations were used to differentiate PAHs from pyrolitic to petrogenic and mixed origins. The results suggested that the main sources of PAHs in sediments from the studied region were mixed pyrolitic and petrogenic. Furthermore, benthic organisms in most of the R. Mirza (*) : M. Mohammadi : A. Fakhri Persian Gulf Research and Studies Center, Persian Gulf University, Bushehr, Iran e-mail:
[email protected] I. Faghiri Department of Marine Biology, Faculty of Marine Sciences, Khorramshahr University of Marine Science and Technology, Khorramshahr, Iran E. Abedi : A. Azimi Persian Gulf Research Station, Iranian National Institute for Oceanography, Bushehr, Iran M. A. Zahed Department of Civil Engineering, Auburn University, Auburn, AL 36849, USA
investigated areas were not at ecotoxicological risk, according to the results from the effects range low (ERL)/effects range median (ERM) techniques suggested by the US Sediment Quality Guidelines (SQGs). Keywords PAHs . Sediment . Pollution . Iran . Persian Gulf
Introduction Polycyclic aromatic hydrocarbons (PAHs) are a group of widely distributed persistent organic compounds (POPs). Because of their persistence, carcinogenicity, and mutagenic and toxic effects in marine environments, these compounds have received increasing scientific interest in the past three decades (Kennesh 1992; Benlahcen et al. 1997; Yim et al. 2007; Oliva et al. 2010). PAH compounds originate from various anthropogenic sources, including fossil fuel combustion, municipal and industrial effluents, atmospheric transport and the spillage or disposal of oil and petroleum products as well as urban and agricultural runoff, asphalt production, and waste incineration (Neff 1979; Eisler 1987; Woodhead et al. 1999; Mccready et al. 2000). Low levels of PAHs found in the environment are generated by natural events such as forest fires, natural seepage, and volcanic activities. The United States Environmental Protection Agency (US-EPA) and the European Union have identified 16 PAHs as priority pollutants, some of which, for example,
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benzo(a)anthracene, chrysene, and benzo(a)pyrene, are considered mutagenic, carcinogenic, and teratogenic (Sverdrup et al. 2002; Qiao et al. 2006). Because of their hydrophobicity and low water solubility and vapor pressures, PAHs tend to accumulate rapidly in sediment and various organic components in marine environments (Chiou et al. 1998; Savinov et al. 2003; Magi et al. 2002; Kannan et al. 2003; Koh et al. 2004). Levels of PAHs in sediments vary according to proximity to areas of human activity (Bihari et al. 2007) and are notably elevated near industrial and urban centers. The Persian Gulf is a semi-enclosed sea located in a subtropical, high-pressure zone that is characterized by low precipitation and high aridity. As an ecosystem, this area is exposed to multiple environmental stresses. Situated within the richest oil province in the world, the region hosts more than 67 % of the world’s oil reserves. Two thirds of global oil tanker traffic takes place in the Persian Gulf, and this traffic contributes to the accumulation of hydrocarbons in sediments. Oil-related activities, ranging from exploration to exportation, significantly damage the components of the ecosystem, including coral reefs, algal mats, mangrove, and other habitats (Tolosa et al. 2005; Sheppard et al. 2010). Along the Iranian coast of the Persian Gulf, offshore oil production, oil refinery, oil/water separators on production platforms, tanker traffic, port areas, fishery wharfs, and fishery and tourism activities also adversely impact the environment. Little information is available about the PAH distribution in the Iranian coast of the Persian Gulf. This study is an initial attempt to describe the current status of PAH contamination in coastal sediments from the area on a national scale. PAH contamination was Fig. 1 Sampling sites in the north of the Persian Gulf (surface sediments of the southern coast of Iran)
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determined in samples collected from the Iranian coast of the Persian Gulf, the possible sources of the PAHs were identified using diagnostic ratios of PAHs, and the potential toxicological impacts were evaluated. It is hoped that this data will provide a reference to inform the environmental management of the area.
Materials and methods Sampling Thirty surface sediment samples were collected from the shorelines of Khure-Musa, Bushehr, Hormuzgan, and Chabahar Bay on the Iranian coast of the Persian Gulf in May 2012. The locations of the sampling sites are shown in Fig. 1. The positions of the sampling sites were recorded using GPS (Table 1). Samples were collected during low tide using a stainless steel grab sampler. Samples were immediately transferred to hexanerinsed glass bottles with aluminum foil caps and transported in dry ice to the laboratory for processing. Sample preparation and extraction All solvents used were of analytical reagent grade. Dichloromethane (DCM) and hexane were purified by duplicate distillation in a glass apparatus. Anhydrous sodium sulfate and silica gel were baked at 450 °C for 4 h before use. All glassware and equipment in contact with the sample were heated in a muffle furnace or rinsed with acetone before use. Sample extraction, preparation, and analysis procedures for PAHs were conducted
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Table 1 Locations of sampling stations Station
Site no.
Region
Latitude
Longitude
Jafari
1
Khure-Musa
30°25′ N
49°06′ E
Ahmadi
2
Khure-Musa
30°27′ N
49°07′ E
Arduole
3
Khure-Musa
30°27′ N
49°09′ E
Ghazale
4
Khure-Musa
30°25′ N
49°11′ E
Nazdik dahane
5
Khure-Musa
30°24′ N
49°12′ E
Ghanam
6
Khure-Musa
30°22′ N
49°08′ E
Genaveh
7
Bushehr
29°39′ N
50°24′ E
Bushehr (S)
8
Bushehr
28°50′ N
50°52′ E
Bushehr (N)
9
Bushehr
28°54′ N
50°48′ E
Dayer
10
Bushehr
27°49′ N
51°55′ E
Nayband
11
Bushehr
27°24′ N
52°38′ E
Narmtanan
12
Hurmozgan
26°32′ N
54°51′ E
Eskele shahr
13
Hurmozgan
26°32′ N
54°51′ E
Kong
14
Hurmozgan
26°25′ N
54°56′ E
Khamir
15
Hurmozgan
26°56′ N
53°25′ E
Pohl
16
Hurmozgan
26°58′ N
55°45′ E
Homa
17
Hurmozgan
27°10′ N
56°15′ E
Haghani
18
Hurmozgan
27°10′ N
56°16′ E
Gorsozan
19
Hurmozgan
27°10′ N
56°14′ E
Hormoz
20
Hurmozgan
27°10′ N
56°17′ E
Khaje ata
21
Hurmozgan
27°10′ N
56°18′ E
Dolat
22
Hurmozgan
27°11′ N
56°20′ E
Velayat
23
Hurmozgan
27°11′ N
56°19′ E
Ramin
24
Chabahar
25°16′ N
56°14′ E
Darya Bozorg
25
Chabahar
25°16′ N
56°17′ E
Darya Kochak
26
Chabahar
25°18′ N
56°18′ E
Keshtisazi
27
Chabahar
25°21′ N
56°20′ E
Ab shrin
28
Chabahar
25°26′ N
56°19′ E
Konarak
29
Chabahar
25°23′ N
56°20′ E
Pozm
30
Chabahar
25°21′ N
56°19′ E
following the method described by Zakaria et al. (2002) and Zakaria and Mahat (2006). Briefly, a solution of five surrogate internal standards (naphthalene-d 8 , phenanthrene-d10, p-terphenyl-d14, chrysene-d12, and perylene-d12) was added directly to the samples before extraction to monitor and account for any losses during sample preparation. Sediment samples were mixed with sodium sulfate and then extracted using a Soxhlet apparatus for 8 h using 350 ml DCM (80 cycles), followed by activated copper treatment for elemental sulfur removal. After extraction, total organic extract was concentrated until near dryness using a rotary evaporator for further cleanup. The concentrated extracts were passed first
through a chromatography column (0.9 cm inner diameter packed with 5 % activated silica gel) to remove polar compounds. The eluents were collected and passed through a second chromatography column (4.5 mm inner diameter, packed with fully activated silica gel) to fractionate hydrocarbons. The first fraction contained the aliphatic hydrocarbons eluted by 4 ml hexane. PAH fractions were eluted with 14 ml of a 3:1 (v/v) dichloromethane/hexane mixture. The PAH fractions were further reduced to near dryness using a purified nitrogen steam and diluted to a final volume of 200 μl using iso-octane containing p-terphenyl-d14 as internal injection standard. Gas chromatography–mass spectrometry analysis Samples were analyzed by gas chromatography–mass spectrometry (GC-MS) using the HP 6890 gas chromatography series using a mass detector equipped with a split/splitless injector. An HP-5MS capillary column (30× 0.25 mm inner diameter×0.25 μm film thickness) was used in the analysis (Hewlett-Packard). The column temperature was initially held at 70 °C for 2 min, raised to 150 °C at a rate of 300 °C min−1, raised to 310 °C at a rate of 4 °C min−1, and subsequently held at 310 °C for 5 min. The samples were injected using the splitless mode at an injection temperature of 280 °C. Helium carrier gas was delivered at a constant flow rate of 1 ml/min−1. A selected ion monitoring mode (SIM) was employed using molecular ions. Identification of PAHs in the sediment samples was based on their retention time and the ion m/z ratio for the authentic PAH standards. Quality assurance/quality control A quality assurance/quality control (QA/QC) study was carried out by monitoring the recovery of surrogate standards. The acceptable range of surrogate standard recovery was 40–120 %. Each batch of sediment samples was processed with a method blank (solvent) and a spiked blank (standards spiked into the solvent). The relative standard deviation (RSD) of individual PAHs identified in the sample extracts was 5,000 ng g−1, respectively. Based on this classification, the samples of surface sediments from the Iranian coast of the Persian Gulf exhibit low to high levels of PAH pollution. The total PAH concentrations in these sediment samples were similar to those observed for other coastal areas receiving large anthropogenic inputs from
Table 3 Comparison of concentrations of PAHs in coastal sediments from the Persian Gulf with worldwide area (ng g−1 dw) Area
∑PAHs (ng g−1 dw)
Tabasco State, Mexico
454–3,120
Moderate to high
Botello et al. (1991)
West Mediterranean Sea
1.5–20,440
Low to very high
Baumard et al. (1998)
Pollution level
References
Masan Bay, Korea
207–2,670
Moderate to high
Yim et al. (2005)
Chesapeake Bay, USA
0.56–180
Low to moderate
Foster and Wright (1988)
6.7–813
Low to moderate
Macias-Zamora et al. (2002)
Todos Santos Bay, Mexico Taranto Gulf, Italy
325–5,193
Low to moderate
Storelli and Marcotrigiano (2000)
Tianjin, China
787–1,943,000
Moderate to very high
Shi et al.(2005)
Low
Olajire et al. (2005)
Niger Delta, Nigeria Dar es Salaam, Tanzania Santander Gulf, Spain Arcachon Bay, France
21–72 77.9–24,600
Low to very high
Gaspare et al. (2008)
20–25,800
Low to very high
Viguri et al. (2002)
32–4,120
Low to very high
Baumard et al. (1998)
Moderate
Liu et al. (2007) Gogou et al. (2000)
Coastal areas, China
189–637
Mediterranean Sea
14.6–158.5
Low to moderate
Northwest Mediterranean Sea
86.5–48,090
Low to very high
Benlahcen et al. (1997)
Izmit Bay, Turkey
250–25,000
High to very high
Tolun et al. (2001)
Hadhramout Coast, Yemen Marine environment, Korea
2.2–604 8.80–18,500
Low to moderate
Mostafa et al. (2009)
Low to high
Yim et al. (2007)
Caspian Sea sediments, Iran
94–1,789
Low to high
Tolosa et al. (2005)
Gulf and the Gulf of Oman, Oman
1.6–30
Low to very high
Tolosa et al. (2005)
Gulf and the Gulf of Oman, Bahrain
13–6,600
Gulf and the Gulf of Oman, Qatar
0.55–92
Low to very high
Tolosa et al. (2005)
Low
Tolosa et al. (2005)
Gulf and the Gulf of Oman, UAE
0.6–9.4
Low
Tolosa et al. (2005)
Persian Gulf, Boushehr, Iran
41–227
Low to moderate
Mirza et al. (2012)
Persian Gulf, Iran
93–4,077
Low to high
Present study
The pollution levels are assigned as follows: low, 0–100; moderate, 100–1,000; high, 1,000–5,000; very high, >5,000 ng g−1 (Baumard et al. 1998)
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urban and industrial activities, such as the marine environment of Korea and the Caspian Sea in Iran. However, the PAH concentrations observed in this study were lower than those observed for the West Mediterranean Sea; Tianjin, China; Dar es Salaam, Tanzania; Santander Gulf, Spain; Arcachon Bay, France; Izmit Bay, Turkey; Persian Gulf and the Gulf of Oman, Bahrain; and the northwest coast of the Mediterranean Sea (Table 3). Composition and source identification of PAHs The study of the composition of the PAH mixtures can provide useful information about their sources and transport pathways. The distribution patterns of PAHs in the surface sediments from the southern coast of Iran according to ring size (two to six) are shown in Fig. 2. The distribution of PAHs in the intertidal area of the southern coast of Iran is very homogeneous. The four-ring PAHs were found to be the most abundant compounds, followed by the three-ring and tworing PAHs. The six-ring PAHs, such as indeno[1,2,3cd]pyrene and benzo(ghi)perylene, were absent from sites 11, 17, and 21. This result is consistent with typical PAH compositions observed in sediments from other polluted areas (Khim et al. 2001; Kannan et al. 2001). High molecular weight PAHs in sediment samples are more likely to be transported to the sediment bed, due to their increased sorption and resistance to degradation. High molecular weight PAHs have been commonly observed to be dominant in sediments from marine or
estuarine environments (Mostafa et al. 2009; Readman et al. 1987). The PAH composition patterns observed are similar to other areas (Table 2). PAHs are toxic to aquatic organisms, and some have carcinogenic or mutagenic characteristics (Boxall and Maltby 1997). The IARC (1987) has identified some PAHs [benzo(a)anthracene (BaA), chrysene (Chry), benzo[b]fluoranthene (BbF), benzo(k)fluoranthrene (BkF), benzo(a)pyrene (BaP), indeno(1,2,3-cd)pyrene (IP), and DahA) as probable/ potential carcinogens. Total concentrations of potentially carcinogenic PAHs in the sediments from the southern coast of Iran varied from 46 to 1,704 ng g−1 dry weight (Table 2). PAHs from different sources are deposited in different PAH patterns. Anthropogenic sources of PAHs in marine sediments are pyrogenic or petrogenic. Pyrolytic PAHs are produced during incomplete combustion of coals, carbon, wood, and fossil fuels and predominantly act as high molecular weight parent PAH compounds (having four or more aromatic rings). In contrast, petrogenic PAHs (from the discharge of petroleum-related materials) contain only two or three aromatic rings (Neff 1979; Burgess et al. 2003; Wang et al. 2006). Different sources are believed to result in characteristic ratios of PAH concentrations, and these ratios have been widely used to infer the source of PAH contamination (Yunker et al. 2002). For example, PAH ratios, such as phenanthrene/anthracene (Phe/Ant), fluoranthene/pyrene (Flu/Pyr), low molecular weight/
100% 80% 60% 40% 20% 0% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Site 2ring
3ring
4ring
5ring
Fig. 2 Polycyclic aromatic hydrocarbon (two to six rings) distribution patterns
6ring
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Fig. 3 LMW/HMW ratio values for sediment samples
LMW/HMW 3
2
1
1 2 3 4 5 6 7 8 9 101112131415161718192021222324252627282930
0
PAHs in sediments (Budzinski et al. 1997; De Luca et al. 2005). The ΣLPAHs include naphthalene (Naph), acenaphthylene (Acen), acenaphthene (Ace), fluorene (Fl), Phe, and Ant; the ΣHPAHs include Flu, Pyr, Chry, BaA, BbF, BkF, BaP, IP, and benzo(ghi)perylene (BiP) (Table 2). Results from the present study indicate that LPAH/HPAH ratios at sites 1, 2, 3, 4, 5, 6, 16, 24, and 29 were 10 and a Flu/Pyr ratio of
