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Organochlorine pesticides and PCB residues in sediments of Alexandria Harbour, Egypt
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Page, D.S., Boehm, P.D., Douglas, G.S., Brown, J.S., Bence, A.E., Burns, W.A., Mankiewicz, P.J., 2000. Mass balance constraints on the sources of the petrogenic hydrocarbon background in offshore sediments of Prince William Sound and the Gulf of Alaska. Proceedings of the 23rd Arctic and Marine Oil Spill Program (AMOP) Technical Seminar, 1–9. Rogers, H.R., 2002. Assessment of PAH contamination in estuarine sediments using the equilibrium partitioning-toxic unit approach. The Science of the Total Environment 290, 139–155. Rose, N.L., Rippey, B., 2002. The historical record of PAH, PCB, trace metal and fly-ash particle deposition at a remote lake in north-west Scotland. Environmental Pollution 117, 121–132. Simpson, C.D., Harrington, C.F., Cullen, W.R., 1998. Polycyclic aromatic hydrocarbon contamination in marine sediments near Kitimat, British Columbia. Environmental Science and Technology 32, 3266–3272.
Yang, G.-P., 2000. Polycyclic aromatic hydrocarbons in the sediments of the South China Sea. Environmental Pollution 108, 163– 171. Wang, X.-C., Zhang, Y.-X., Chen, R.F., 2001. Distribution and partitioning of polycyclic aromatic hydrocarbons (PAHs) in different size fractions in sediments from Boston Harbour, United States. Marine Pollution Bulletin 42, 1139–1149. Widdows, J., Donkin, P., Staff, F.J., Matthiessen, P., Law, R.J., Allen, Y.T., Thain, J.E., Allchin, C.R., Jones, B.R., 2002. Measurement of stress effects (scope for growth) and contaminant levels in mussels (Mytilus edulis) collected from the Irish Sea. Marine Environmental Research 53, 327–356. Woodhead, R.J., Law, R.J., Matthiessen, P., 1999. Polycyclic aromatic hydrocarbons in surface sediments around England and Wales, and their possible biological significance. Marine Pollution Bulletin 38, 773–790.
0025-326X/02/$ - see front matter Ó 2002 Elsevier Science Ltd. All rights reserved. PII: S 0 0 2 5 - 3 2 6 X ( 0 2 ) 0 0 3 0 6 - 5
Organochlorine pesticides and PCB residues in sediments of Alexandria Harbour, Egypt Assem O. Barakat a
a,*
, Moonkoo Kim b, Yoarong Qian b, Terry L. Wade
b
Department of Environmental Sciences, Faculty of Science, Alexandria University, 21511 Moharrem Bey, Alexandria, Egypt b Geochemical and Environmental Research Group, Texas AM University, College Station, Texas, TX 77845, USA
Abstract Persistent organochlorine compound concentrations were determined for 23 surface sediment samples collected from Alexandria Harbor, Egypt. Total PCB concentrations ranged from 0.9 to 1210 ng/g with four to seven Cl-substituted biphenyls being the most prevalent PCBs congeners. Different PCB congener distribution patterns were observed, probably reflecting different inputs and attenuation at various locations. Total DDT concentrations varied from <0.25 ng/g to 885 ng/g. The ratios of DDTs (2,40 - and 4,40 DDT)/total DDTs (DDTs plus metabolites) in sediment samples from certain sites were 0.86 or higher, indicating little attenuation or recent input of DDT. Total chlordane (the sum of heptachlor and its epoxide, oxy-, c- and a-chlordane and cis þ trans-nonachlor) ranged from <0.25 to 44 ng/g with the highest concentration found in the Arsenal Basin. The geographic distributions of PCBs, total DDTs and total chlordane were similar. Chlorinated benzenes (CBs), hexachlorocyclohexanes (HCHs), aldrin, dieldrin, endrin, chloropyrifos, endosulfan, mirex and pentachloroanisole were below detection limits or detected at low concentrations in most of the samples. Sites that were contaminated with high concentrations of organochlorine compounds were associated with dense population and low energy environment. The contamination levels of PCBs, total DDTs and total chlordane were in high range compared to other locations worldwide. Ó 2002 Elsevier Science Ltd. All rights reserved. Keywords: Organochlorine pesticides; PCBs; Marine sediments; Persistent organic pollutants; Alexandria Harbour, Egypt
Coastal sediments act as temporary or long-term sinks for many classes of anthropogenic contaminants. Organochlorines (OCs), such as polychlorinated biphenyls (PCBs) and chlorinated pesticides, represent an important group of persistent organic pollutants (POPs) that have caused worldwide concern as toxic environ-
*
Corresponding author. Tel.: +20-354-63250; fax: +20-354-63305. E-mail address: [email protected] (A.O. Barakat).
mental contaminants (Bildeman and Olney, 1974; Tanabe et al., 1982; Wade et al., 1988; Iwata et al., 1994; Allen-Gil et al., 1998; Wu et al., 1999). Many POPs are believed to be possible carcinogens or mutagens and are of considerable concern to human and environmental health. Although most of these compounds are no longer in use, the persistence of many OC compounds in the environment has prompted continued studies aimed at evaluating environmental quality for wildlife and humans (e.g., Wade et al., 1998).
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Studies on the environmental health of Alexandria Harbour have concentrated in the past mostly on simple chemical and bulk analysis of sediments and water (ElSayed et al., 1988; EA-ESTI, 1997). Few studies on the status of persistent organic contaminants in the coastal areas in Egypt have been conducted (Abdallah, 1992; Abdallah and Abbas, 1994). Alexandria Harbour plays important roles in both commercial activities for the economic development of Egypt and as an ecosystem to nurture coastal marine life. However, there is limited information available on the status of POPs in this important ecosystem. The Alexandria Harbour provides shelter from the open sea (Mediterranean Sea) giving rise to its use as a natural marina (Fig. 1). The narrow harbour entrance and the limited tidal range have made the harbour a lagoon-like enclosure. The rapid development of the Alexandria Harbour in the last few years and the continued increase in commercial and industrial activities within the harbour exert additional stress. The water quality in the harbour is potentially impacted by
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wastewater disposal (both untreated sewage and industrial) which are currently discharged to the harbour and the Mediterranean Sea directly via El-Mex Pump Station and through numerous storm and combined sewer outfalls located within the harbour area. The harbour is also heavily influenced by agricultural run off from the El-Mahmoudiya and Noubaria canals. OC pesticides have been used substantially in Egypt for the control of agricultural pests. Although the usage of PCBs in Egypt is not known, the past use of these substances in transformers, electrical equipments, ship painting and other industrial has been common. The objectives of this investigation were to assess the occurrence and distribution of persistent OC pesticides and PCB residues in sediments of Alexandria Harbour and to evaluate their potential effects on aquatic organisms. Twenty three sediment samples were collected within the harbour (Fig. 1) to cover regions affected by intense activities, freshwater input, wastewater outfalls as well as relatively pristine areas. In addition, two reference
Fig. 1. Location map of surface sediment sampling stations in Alexandria Harbour, Egypt.
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sediment samples, collected from Stanley Bay and Montazah beach located along the coast of Alexandria city were analyzed with this sample set. Surface sediment samples were taken with an Ekman grab sampler. Collected samples were frozen on dry ice and transferred to the laboratory for processing. Sample preparation and analysis methods have been described in Wade et al. (1988). Briefly, about 10 g of freeze-dried sediment was Soxhlet-extracted with methylene chloride. Concentrated extracts were fractionated with alumina/silica gel (80–100 mesh) column chromatography. Target analytes were eluted from the column with 50 ml of pentane (aliphatic fraction) and 200 ml of 1:1 pentane–dichloromethane (aromatic/PCB/pesticide fraction). The fractions were then concentrated to 1 ml using Kuderna–Danish tubes heated in a water bath at 60 °C. The surrogates dibromooctafluorobiphenyl (DBOFB), PCB103, and PCB198 were added to the samples prior to extraction. The chlorinated pesticides and PCBs were analyzed by gas chromatography in the spitless mode using an electron capture detector (ECD). A 30 m 0:32 mm i.d. fused silica column with DB-5 bonded phase (JW Scientific, Inc.) provided component separations. The chromatographic conditions for the pesticide–PCB analysis were 100 °C for 1 min, then 5 °C min1 to 250 °C, hold for 1 min, and then 10 °C min1 to 300 °C and a final hold of 5 min. The internal standard, tetrachlorom-xylene (TCMX), was added prior to GC/ECD analysis to monitor the recovery of surrogate. A standard solution containing only PCBs was used to confirm the identification of each PCB congener. The QA/QC procedures included analysis of matrix spikes, duplicates, laboratory blanks and certified reference material (Wade and Cantillo, 1994). For data presentation all concentrations below the method detection limits were assigned a value of 0.25 ng/g (dry weight) as the estimated average detection limit. The instrument was calibrated by injection of the standards component mixture at five different concentrations, prior to analysis of the samples. The following compounds were included in this study: 2,40 -DDT (2,40 -dichloro-diphenyltrichloroethane), 4,40 DDT and their degradation products 2,40 -DDD (2,40 dichloro-diphenyldichloroethane), 4,40 -DDD, 2,40 -DDE (2,40 -dichlorodiphenyltrichloroethene) and 4,40 -DDE, chlordane related compounds, chlorinated benzenes (CBs), hexachlorocyclohexanes (HCHs), aldrin, dieldrin, endrin, chloropyrifos, endosulfan, mirex and pentachloroanisole. For simplicity, the following nomenclature will be used in this paper: DDTs for the sum of 2,40 - and 4,40 DDT; DDDs for the sum of 2,40 - and 4,40 -DDD; DDEs for the sum of 2,40 - and 4,40 -DDE; total DDTs for the sum of DDTs, DDDs, and DDEs; total chlordane for the sum of heptachlor and its epoxide, oxy-, c, and achlordane, and cis- and trans-nonachlor; CBs for the sum
of 1,2,4,5- and 1,2,3,4-tetrachlorobenzene (TCB), pentachlorobenzene (PeCB) and hexachlorobenzene (HCB); HCHs for the sum of a-,b-, c-, and d-hexachlorohexane. Furthermore, the sum of 99 individual PCB congeners will be referred to as PCBs. PCBs concentrations in the sediments ranged from 0.9 to 1210 ng/g with a median of 260 ng/g (Table 1). The 21 harbour sites had PCBs levels higher than 37 ng/ g. The reference sites and the remaining open water sites had PCBs concentrations between 0.9 and 2.8 ng/g. Highest concentrations of PCBs were found in samples collected from enclosed vessel anchorage basins within the inner harbour (stations 1–9, Fig. 1). PCBs in samples collected from the inner harbour in the Arsenal Basin (1210 ng/g; station 1) and near El-Mahmoudiya Quay (556 and 477; stations 8 and 6, respectively) were among the highest sediment PCBs concentrations. These locations also had high concentrations of heavy metals and butyltin compounds (Barakat et al., 2001). Concentrations of PCBs in samples collected from enclosed bays and ship docking facilities in the Outer Harbour were also high. Two sites (stations 12 and 14) near a ship building facility close to Coal Quay had PCBs concentrations of 479 and 410 ng/g, respectively. High PCBs concentrations were also found in samples from the Marine Ship Lift and Dry Dock Facilities (218 ng/g, station 10), and the Harbour Bank area (178 and 206 ng/g; stations 17 and 18, respectively). PCBs levels were lower in the open mooring and anchorage areas (97–152 ng/g; sites 13, 15, and 16, Fig. 1) and ship channels (63–109 ng/g; sites 11, 20 and 21) where heavy traffic of tankers and commercial cargo boats are common. PCBs concentrations were low in open areas outside the harbour (0.9 and 2.8 ng/g, stations 22 and 23, respectively). The spatial distribution pattern of PCBs indicates that PCB contamination may have been associated with local ship activities and wastewater effluent outfall areas. The high concentrations of PCBs at station 1 in the Arsenal Basin were probably attributed to the operations of boat repairing facilities of Alexandria Company, including ship repainting, engine overhaul, and maintenance operations. This site is also located near large outfalls of storm water and domestic and industrial wastewaters. The Arsenal Basin is a semi-enclosed embayment with limited water exchange with the open sea. This may contribute to the accumulation of persistent contaminants in this basin. Similarly, the high concentrations of PCBs at stations near El-Mahmoudiya Quay may result from outflows from ElMahmoudiya Canal (Fig. 1). In addition, there were several local wastewater discharges to this area. Persistence of PCBs in aquatic sediments is due to their low rate of degradation and vaporization, low water solubility, and partitioning to particles and organic carbon (Kennish, 1992). The physicochemical
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Table 1 Concentrations (ng/g, dry wt) of PCBs and chlorinated pesticides in sediments of Alexandria Harbour, Egypt P Station Sample location PCBsa DDTsb Chlordanec HCBsd CHse Aldrin Dieldrin Endrin no. 1 2 3 4 5 6 7 8 9 10
11 12 13 14 15 16
17 18 19 20 21 22 23 Ref. 1 Ref. 2
Arsenal Basin Arsenal Basin Arsenal Basin Boathouse El-Mahmudiya Quay El-Mahmudiya Quay El-Mahmudiya Quay El-Mahmudiya Quay Ship Pass (inner harbour) Marine Ship Lift and floating dry dock Ship Pass (outer harbor) Coal Quay Coal Basin Shipyard/ Mooring Area Shipyard/ Mooring Area Mina El-Qamariya (Timber Wharves) Harbour Bank Mooring Area Petroleum Harbor Harbor Inlet (inside harbor) Harbor Inlet (outside harbor) Ship Pass (open sea) Ship Pass (open sea) Montazah Beach Stanley Bay
Chloropyrifos
Mirex
Endosulfan
1211 114 280 349 339
885 21 189 27 58
44 8.7 12 9.3 7.6
2.4 0.5 1.5 2.9
0.8 0.4 0.8 0.9 0.3
13 1.5 7.9 1.2
0.4
22 2.1 1.8 5.8
477
23
4.6
3.3
22
274
40
4.8
0.9
3.9
1.2
556
203
29
6.0
4.6
3.1
6.7
51
203
36
1.8
0.3
0.4
0.4
1.0
218
34
1.3
1.2
2.1
1.1
0.9
92
10
1.4
0.6
1.1
0.1
479 128 410
66 58 119
3.8 2.1 4.0
0.5 0.7 0.9
1.4 1.3 0.9
1.4 0.8
0.7
152
29
2.2
1.7
0.6
0.4
3.5
98
15
1.0
0.9
0.5
0.3
0.4
178 206 37
30 97 13
1.9 2.1 0.3
1.0 2.5 0.4
0.7 1.1
0.7 1.5
109
27
1.0
1.1
0.4
2.3
63
8.9
1.2
0.6
0.9
0.3
2.8
0.7
1.0 0.9
a
PCB represent the sum of over 96 detected congeners. DDT is the sum of 2,40 + 4; 40 forms of DDT and its breakdown products, 2,4 + 4,40 -DDE and DDD. Concentrations of high DDTs were confirmed with a gas chromatography/mass spectrometry analysis of the samples with high DDT concentrations. c Chlordane is the sum of heptachlor and its epoxide, oxy-, c, and a-chlordane, cis- and trans-nonachlor. d CB is the sum of 1,2,4,5- and 1,2,3,4-TCB, PeCB and HCB. e HCH is the sum of a-, b-, c-, and d-hexaachlorohexane. f
properties as well as the degradation of PCBs vary widely and depend on the number and position of chlorine atoms in the biphenyl rings (Reutergarth, 1980; Abramowicz et al., 1993; Rhee et al., 1993). The PCB congeners identified in sediments of this study were predominantly tetra- to hepta-chlorinated biphenyls (Fig. 2). The most abundant PCB congeners detected in these sediment samples were PCB153/132 and PCB138/160
which are commonly found in environmental samples. Concentrations of PCB136, PCB180, PCB118, PCB107, PCB110, PCB170, PCB190, PCB187, PCB149 and PCB123 were at intermediate concentration levels. The latter PCB congeners have low to medium toxicity (Fernandez et al., 1999). The more toxic PCB congeners, such as PCB77, PCB81, PCB194, PCB126, PCB169 and PCB105, were present at low concentrations in these samples (Figs. 2 and 3).
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Fig. 2. Concentrations of PCBs represented as chlorination levels in Alexandria Harbour sediments.
Although the observed trends in PCB congeners composition were similar in some of the samples (e.g. between S-1 and S-3, and between S-5, S-7 and S-10, Fig. 3) the distribution patterns are, in general, different among the sediments of this study area (Fig. 3), which may indicate different input sources. The usage of PCB in Egypt is not well established, but the use of PCBs in transformers, electrical equipment, and other industries is common. The results from this study suggest that, owing to their persistence, PCBs contamination are widespread at Alexandria Harbour. Concentrations of total DDTs varied from <0.25 to 885 ng/g (dry weight) with a median concentration of 87 92 ng/g (Table 1). DDTs (2; 40 þ 4; 40 -DDT) and/or their breakdown products were detected in all of the samples inside the harbour. Samples from stations 22 and 23, which are located in outside the harbour (Fig. 1), and reference samples contained no detectable DDTs. Similar to PCBs, high concentrations of total DDTs were encountered at locations within the inner harbour and at sites located near ship activities and storm sewer outfalls (stations 1, 3, 8, 14 and 18; 100–885 ng/g). Other sites with elevated concentrations of total DDTs (58–66 ng/g) are stations 5, 12, and 13. The total DDTs concentrations were in the range from 10 to 40 ng/g (average of 26 7 ng/g) in the remaining samples. The high concentrations of total DDTs and related compounds in these sediments indicate that DDT usage was heavy and the harbour has received significant inputs of DDTs. DDTs undergoes degradation to DDDs and DDEs in natural environment by chemical and biological processes (Wedemeyer, 1967; Baxtor, 1990). Fig. 4 shows DDTs and their metabolites as a percentage of total DDTs at the different sampling sites. Over 85% of the total DDTs in sediments from stations 1, 3, and 6 was
present as DDTs and particularly as 2,40 -DDT. The dominance of DDTs in the sediment indicates slow degradation of DDTs or recent inputs of fresh DDT at these locations (Tavares et al., 1999; Yuan et al., 2001). Station 12 also showed significant concentrations of DDTs (38%). DDDs and DDEs were predominant in the remaining samples, with DDDs and DDEs representing over 75% of total DDTs. DDTs were, therefore, not newly released into those locations and were mainly present as metabolites. DDDs accounted for the majority of DDT related compounds at these locations (Fig. 4). The dominance of DDDs over DDEs in these sediments indicates reductive dechlorination of DDTs to DDDs under anaerobic conditions (Wedemeyer, 1967; Baxtor, 1990). This observation is in agreement with the fact that Alexandria Harbour is a semi-closed bay with restricted water exchange with the open ocean and the sediments were anoxic. DDT was widely used in Egypt on a variety of agricultural crops and for the control of disease vectors. The largest agricultural use of DDT has been on cotton, which accounted for more than 80% of the use before its ban. Although its usage was banned in 1988, its detection, along with detection of its breakdown products (i.e., DDEs þ DDDs), in sediments is expected because the reported environmental half-life of DDTs is estimated as 10–20 years (Woodwell et al., 1971; Sericano et al., 1990). Sediment concentrations of total chlordane ranged from <0.25 to 44 ng/g (dry weight) with a median concentration of 6 ng/g (Table 1). a-Chlordane was the major chlordane isomer in all the samples. This is expected since a-chlordane is one of the main components of technical grade chlordane (Dearth and Hites, 1991). Similar to the distribution of DDT and its metabolites,
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Fig. 3. Relative abundance of selected PCB congeners having the highest average concentrations in representative sediment samples from Alexandria Harbour.
high concentrations of total chlordane were encountered in the inner harbour area (Stations 1–8, Fig. 1) with the highest residue concentrations (44 ng/g) found at station 1 in the Arsenal Basin. These sites in the inner harbour also had the highest concentrations of total PCBs and total DDTs. In contrast to stations 1–8, chlordane concentrations at the remaining sites in the outer harbour area were low (less than 4 ng/g), indicating that the contamination of sediments in the outer Alexandria Harbour by chlordane related compounds was minimal. In addition, chlordanes were not detected at stations 22 and 23 and the reference stations.
The CBs, such as 1,2,4,5-TCB, 1,2,3,4-TCB, and PeCB, may be metabolites of the commercial pesticide HCB or other CBs, e.g. pentachlorophenol (Wang and Jones, 1994). The concentrations of these CBs and HCH were either below detection limits or low (Table 1). Highest concentrations of chloropyrifos and endosulfan II were found in the inner harbour region. Chloropyrifos (<0.25–51) was detected in 26% of the samples with highest levels at station 8, while endosulfan II (<0.25–22) was detected in 44% of the samples with highest concentrations at the Arsenal basin (station 1). Chloropyrifosis highly toxic to molluscs, fish and
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Fig. 4. Percentage of total DDTs represented by DDTs and their metabolites DDDs and DDEs in sediments from Alexandria Harbour.
crustaceans (Briggs, 1992) and it has been reported in Biota samples (Pait et al., 1992). Endosulfan was reported to be responsible for more fish deaths in US estuaries and coastal areas between 1980 and 1989 than any currently used pesticide and was ranked as the most hazardous of the currently used pesticides considered (Pait et al., 1992). Aldrin, dieldrin and endrin were found at low concentrations in several samples, with highest results found in sediments near El-Mahmoudiya Quay stations (stations 5, 7 and 8, Table 1). Aldrin (<0.25–4.6 ng/g) was
detected in 30% of the samples analyzed, dieldrin (<0.25–3.1 ng/g) in 35% samples and endrin (<0.25–6.7 ng/g) in 39% samples. Other OC pesticides such as mirex and pentachloroanisole were near or below the method detection limit. Long et al. (1995) conducted an extensive review of articles that provide both concentrations of contaminants in sediment and observed biological effects. They derived consensus values by considering data from all of the studies reviewed and ranked from low to high. A 10th and 50th percentile were then determined and were designated effects range low (ER-L) and effects range median (ER-M). The ER-L and ER-M values for total DDT are 3 and 350 ng/g, for PCBs are 50 and 400 ng/g, and for chlordanes are 0.5 and 6 ng/g, respectively. Total PCB concentrations in the sediments from nearly all the sites except for the reference sites and the two sites located in the open ocean were above the ER-L value and the total PCB concentrations in the samples from five sites (stations 1, 6, 8, 12, and 14) were above the ER-M value that could elicit toxic response for most benthic organism. In addition, the DDT concentrations in samples from all the sites except for the reference sites and sample from the open ocean (station 22 and 23) were above the ER-L value (Table 1). Chlordane concentration exceeded the ER-M at six sites and ER-L at 13 sites. Dieldrin and Endrin concentrations exceeded
Table 2 Comparison of PCB and OC pesticide concentrations (ng/g dry wt) in the sediments from other locations Location
Year
PCBs
Total DDT
Chlordane
HCHs
References
Mediterranean Sea Northwest Basin Open sea
1990 1983
1.4–5.8 0.8
1.2–5.8 0.047
NA NA
NA 0.18a
Tolosa et al. (1995) Burns and Villeneuve (1987)
Coastal Barcelona Offshore Casco Bay, Maine, USA Abu-Quir Bay, Egypt
1990 1991 1989–1991
4.0–64 0.4–485 53–231
4.9–79 <0.2–20 44–223
NA <0.25–4.91 NA
NA <0.07–0.48a 16–82
El-Mex Bay, Egypt
1989–1991
68–164
32.3–87
NA
16–53
Tolosa et al. (1995) Kennicutt et al. (1994) Abdallah (1992), Abdallah and Abbas (1994) Abdallah (1992); Abdallah and Abbas (1994)
Rivers, lakes, estuaries Ebro River, Spain Ebro Prodelta, Spain Rhone Prodelta, France Lake Baikal, Russia Washington, DC, USA Hong Kong, PRC Chinese river/estuaries systems
1995–1996 1990 1990 1992 1991 1997–1998 1996–1998
5.3–1772 1.6–39 38–230 0.08–6.1 68–3200 0.48–97.9 0.05–20
0.4–52 0.8–93 73–704 0.014–2.7 7–160 0.27–14.8 0.1–71
NA NA NA n.d.–0.003 5–153 n.d.–11.3 NA
0.001–0.038 NA NA 0.019–0.12 NA 0.1–16.7 0.2–101
Fernandez et al. (1999) Tolosa et al. (1995) Tolosa et al. (1995) Iwata et al. (1995) Wade et al. (1994) Richardson and Zheng (1999) Hong et al. (1999), Wu et al. (1999), Yuan et al. (2001)
1992 1993
3.2–27 0.05–7.2 0.5–14.2 0.9–1211
1.4–30 4.5–311 1.2–2.3 <0.25–885
NA NA 0.9–5.3 <0.25–44
n.d.–2.3 0.14–1.12 0.1–2.0 0.25–6.0
Connell et al. (1998) Hong et al. (1995) Fox et al. (1988) This study
Harbours Victoria Harbour, Hong Kong Xiamen Harbour, PRC Manukkau Harbour, New Zealand Alexandria Harbour, Egypt NA: no data available. n.d.: not detected. a Reported as c-lindane.
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the ER-L at eight and nine sites, respectively. The high concentrations of PCBs, DDTs, chlordane, dieldrin and endrin in the sediments of Alexandria Harbour, therefore, could cause detrimental biological effects for the benthic organisms (Long and Morgan, 1990). Compared to concentrations reported in coastal environments from other parts of the world, PCB concentrations in surface sediments of Alexandria Harbour were one to two orders of magnitude higher than most of the riverine/estuaries systems (Table 2). However, the concentration of total PCBs in the severely impacted areas from the US and Spain were higher than the Alexandria Harbour area. Similarly, concentrations of total DDT were higher than other harbours and riverine/estuary systems except in some severely contaminated locations, such as in the NW Mediterranean sediments from the Rhone Prodelta, Spain. (Table 2). Chlordane concentrations were also higher than those reported from other locations except for the sediments from Washington, DC area. In comparison, the contamination of sediments in the Alexandria Harbour by PCBs, DDTs and chlordanes appeared to be high on a worldwide basis. In order to determine the sources of the observed contaminants, intense localized sampling and analysis of effluents and runoff patterns would be needed. To determine sediments quality, bioassays of sediments at suspected sites should be conducted to directly assess the potential for biological impacts.
Acknowledgements Analytical support by the laboratory staff at Geochemical and Environmental Research Group, Texas AM University is appreciated. We thank Dr. A.R. Mostafa for help during the sampling activities. A.O. Barakat is grateful to the Fulbright Foundation for a research fellowship.
References Abdallah, A.M., 1992. Determination of DDTs and PCBs residues in Abu-Quir and El-Max Bays, Alexandria, Egypt. Toxicol. Environ. Chem. 36, 89–97. Abdallah, A.M., Abbas, M.M., 1994. Residue level of organochlorine pollutants in the Alexandria Region, Egypt. Toxicol. Environ. Chem. 41, 39–247. Abramowicz, D.A., Brennan, M.J., Van Dort, H.M., Gallagher, E.L., 1993. Factors influencing the rate of polychlorinated biphenyl dechlorination in Hudson River sediments. Environ. Sci. Technol. 27, 1125–1131. Allen-Gil, S.M., Gubala, C.P., Wilson, R.W., Landers, D.H., Wade, T.L., Sericano, J.L., Curtis, L.R., 1998. Organochlorine pesticides and polychlorinated biphenyls (PCBs) in sediments and biota from four US Arctic Lakes. Arch. Environ. Contamin. Toxicol. 33, 378– 387.
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Barakat, A.O., Kim, M., Qian, Y., Wade, T., 2001. Butyltin compounds in sediments from the commercial harbour of Alexandria City, Egypt. Environ. Toxicol. Chem. 20, 2744–2748. Baxtor, R.M., 1990. Reductive dechlorination of certain chlorinated organic compounds by reduced haematin compared with their behaviour in the environment. Chemosphere 21, 451–458. Bildeman, T.F., Olney, C.E., 1974. Chlorinated hydrocarbons in the Sargasso sea atmosphere and surface water. Science 183, 516–518. Briggs, S.A., 1992. Basic Guide to Pesticides: Their Characteristics and Hazards. Taylor Francis, Washington, USA. Burns, K., Villeneuve, J.P., 1987. Chlorinated hydrocarbons in the open Mediterranean ecosystem and implications for mass balance calculation. Mar. Chem. 20, 337–359. Connell, D.W., Wu, R.S.S., Richardson, B.J., Leung, K., Lam, P.K.S., Connell, P.A., 1998. Occurrence of persistent organic contaminants and related substances in Hong Kong marine areas: an overview. Mar. Pollut. Bull. 36 (5), 376–384. Dearth, M.A., Hites, R.A., 1991. Complete analysis of technical chlordane using negative ionization mass spectrometry. Environ. Sci. Technol. 25, 245–254. EA-ESTI (EA Engineering, Science, and Technology), 1997. Environmental Technical Report 9. Mediterranean Sea Environmental Characterization Program. Draft, 13 February. Prepared by EA for Metcalf Eddy International, Alexandria, Egypt. AWP Phase II, USAID Proj. 263-0100. El-Sayed, M.Kh., El-Wakeel, S.K., Rifaat, A.E., 1988. Factor analysis of sediments in the Alexandria western harbour, Egypt. Oceanol. Acta 11, 1–11. Fernandez, M.A., Alonso, C., Gonzalez, M.J., Hernandez, L.M., 1999. Occurrence of organochlorine insecticides, PCBs, and PCB congeners in waters and sediments of the Ebro River (Spain). Chemosphere 38 (1), 33–43. Fox, M.E., Roper, D.S., Thrush, S.F., 1988. Organochlorine contaminants in surficial sediments of Manukau Harbour, New Zealand. Mar. Pollut. Bull. 19(7), 333–336. Hong, H., Xu, L., Zhang, L., Chen, J.C., Wong, Y.S., Wan, T.S.M., 1995. Environmental fate and chemistry of organic pollutants in the sediment of Xiamen and Victoria Harbours. Mar. Pollut. Bull. 31, 229–236. Hong, H., Chen, W., Xu, L., Wang, Z., Zhang, L., 1999. Distribution and fate of organochlorine pollutants in the Pearl River Estuary. Mar. Pollut. Bull. 39, 376–382. Iwata, H., Tanabe, S., Aramoto, M., Sakai, N., Tatsukawa, R., 1994. Persistent organochlorine residues in sediments from the Chukchi Sea, Bering Sea and Gulf of Alaska. Mar. Pollut. Bull. 28, 746– 753. Iwata, H., Tanabe, S., Aramoto, M., Ueda, K., Tatsukawa, R., 1995. Persistent organochlorine residues in air, water, sediments and soils from the Lake Baikal Region, Russia. Environ. Sci. Technol. 29, 792–801. Kennish, M.J., 1992. Ecology of Estuaries: Anthropogenic Effects. CRC Press, Boca Raton, FL. Kennicutt, M.C., Wade, T.L., Presley, B.J., Requejo, A.G., Brooks, J.M., Denoux, G.J., 1994. Sediment contaminants in Casco Bay, Maine: Inventories, sources, and potential for biological impact. Environ. Sci. Technol. 28, 1–15. Long, E.R., Morgan, L.G., 1990. The potential for biological effects of sediments-sorbea contaminants tested in the national status and trends program. NOAA Technical Memorandum NOS OMA-52, Seattle, WA. Long, E.R., Macdonald, D.D., Smith, S.L., Calder, F.D., 1995. Incidence of adverse biological effects with ranges of chemical concentrations in marine and estuarine sediments. Environ. Mgmt. 19, 81–97. Pait, A.S., De Souza, A.E., Farrow, D.R.G., 1992. Agricultural Pesticide Use in Coastal Areas: A National Summary. NOAA, Rockville, USA.
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Reutergarth, L., 1980. Chlorinated hydrocarbons in estuaries. In: Olausson, E., Cato, I. (Eds.), Chemistry and Biogeochemistry of Estuaries. Wiley and Sons, New York, pp. 349–361. Rhee, G., Sokol, R.C., Bethoney, C.M., Bush, B., 1993. Dechlorination of polychlorinated biphenyls by Hudson River sediment organisms: Specificity to the chlorination pattern of congeners. Environ. Sci. Technol. 27, 1190–1192. Richardson, B.J., Zheng, G.J., 1999. Chlorinated hydrocarbon contaminants in Hong Kong surficial sediments. Chemosphere 39, 913–923. Sericano, J.L., Wade, T.L., Atlas, E.L., Brooks, J.M., 1990. Historical perspective on the environmental bioavailability of DDT and its derivatives to Gulf of Mexico oysters. Environ. Sci. Technol. 24, 1541–1548. Tanabe, S., Tatsukawa, R., Kawano, M., Hidaka, H., 1982. Global distribution and atmospheric transport of chlorinated hydrocarbons: HCH (BHC) isomers and DDT compounds in the western Pacific, eastern Indian and Antarctic Oceans. J. Ocean. Soc. Jpn. 38, 137–148. Tavares, T.M., Beretta, M., Costa, M.C., 1999. Ratio of DDT/DDE in the All Saints Bay, Brazil and its use in environmental management. Chemosphere 38, 1445–1452. Tolosa, I., Bayona, J.M., Albaiges, J., 1995. Spatial and temporal distribution, fluxes, and budgets of organochlorinated compounds in Northwest Mediterranean sediments. Environ. Sci. Technol. 29, 2519–2527. Wade, T.L., Atlas, E.L., Brooks, J.M., Kennicutt II, M.C., Fox, R.G., Sericano, J.L., Garcia-Roero, B., Defreitas, D.A., 1988. Gulf of
Mexico status and trends program: trace organic contaminant distribution in sediments and oysters. Estuaries 11, 1171– 1179. Wade, T.L., Cantillo, A.Y., 1994. Use of standards and reference materials in the measurement of chlorinated hydrocarbon residues––chemistry workbook. NOAA Technical Memo NOS ORCA 77 (National Status and Trends Program for Marine Environmental Quality). NOAA, Silver Springs, MD. Wade, T.L., Velinsky, D.J., Reinharz, E., Schlekat, C.E., 1994. Tidal river sediments in the Washington, DC area. II. Distribution and sources of organic contaminants. Estuaries 27, 321–333. Wade, T.L., Sericano, J.L., Gardinali, P.R., Wolff, G., Chambers, L., 1998. NOAAs mussel watch project: current use of organic compounds in bivalves. Mar. Pollut. Bull. 37, 20–26. Wang, M.J., Jones, K.C., 1994. Behavior and fate of chlorobenzenes introduced into soil–plant systems by sewage sludge applications: a review. Chemosphere 28, 1325–1360. Wedemeyer, G., 1967. Dechlorination of 1,1,1-trichloro-2,2-bis(pchlorophenyl)ethane by aerobactor aerogenes. Appl. Microbiol. 15, 569–574. Woodwell, G.M., Craig, P.P., Horton, A.J., 1971. DDT in the biosphere: Where does it go. Science 174, 1101–1107. Wu, Y., Zhang, J., Zhou, Q., 1999. Persistent organochlorine residues in sediments from Chinese river/estuary systems. Environ. Pollut. 105, 143–150. Yuan, D., Yang, D., Wade, T.L., Qian, Y., 2001. Status of persistent organic pollutants in the sediments from several estuaries in China. Environ. Pollut. 114, 101–111.
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Page, D.S., Boehm, P.D., Douglas, G.S., Brown, J.S., Bence, A.E., Burns, W.A., Mankiewicz, P.J., 2000. Mass balance constraints on the sources of the petrogenic hydrocarbon background in offshore sediments of Prince William Sound and the Gulf of Alaska. Proceedings of the 23rd Arctic and Marine Oil Spill Program (AMOP) Technical Seminar, 1–9. Rogers, H.R., 2002. Assessment of PAH contamination in estuarine sediments using the equilibrium partitioning-toxic unit approach. The Science of the Total Environment 290, 139–155. Rose, N.L., Rippey, B., 2002. The historical record of PAH, PCB, trace metal and fly-ash particle deposition at a remote lake in north-west Scotland. Environmental Pollution 117, 121–132. Simpson, C.D., Harrington, C.F., Cullen, W.R., 1998. Polycyclic aromatic hydrocarbon contamination in marine sediments near Kitimat, British Columbia. Environmental Science and Technology 32, 3266–3272.
Yang, G.-P., 2000. Polycyclic aromatic hydrocarbons in the sediments of the South China Sea. Environmental Pollution 108, 163– 171. Wang, X.-C., Zhang, Y.-X., Chen, R.F., 2001. Distribution and partitioning of polycyclic aromatic hydrocarbons (PAHs) in different size fractions in sediments from Boston Harbour, United States. Marine Pollution Bulletin 42, 1139–1149. Widdows, J., Donkin, P., Staff, F.J., Matthiessen, P., Law, R.J., Allen, Y.T., Thain, J.E., Allchin, C.R., Jones, B.R., 2002. Measurement of stress effects (scope for growth) and contaminant levels in mussels (Mytilus edulis) collected from the Irish Sea. Marine Environmental Research 53, 327–356. Woodhead, R.J., Law, R.J., Matthiessen, P., 1999. Polycyclic aromatic hydrocarbons in surface sediments around England and Wales, and their possible biological significance. Marine Pollution Bulletin 38, 773–790.
0025-326X/02/$ - see front matter Ó 2002 Elsevier Science Ltd. All rights reserved. PII: S 0 0 2 5 - 3 2 6 X ( 0 2 ) 0 0 3 0 6 - 5
Organochlorine pesticides and PCB residues in sediments of Alexandria Harbour, Egypt Assem O. Barakat a
a,*
, Moonkoo Kim b, Yoarong Qian b, Terry L. Wade
b
Department of Environmental Sciences, Faculty of Science, Alexandria University, 21511 Moharrem Bey, Alexandria, Egypt b Geochemical and Environmental Research Group, Texas AM University, College Station, Texas, TX 77845, USA
Abstract Persistent organochlorine compound concentrations were determined for 23 surface sediment samples collected from Alexandria Harbor, Egypt. Total PCB concentrations ranged from 0.9 to 1210 ng/g with four to seven Cl-substituted biphenyls being the most prevalent PCBs congeners. Different PCB congener distribution patterns were observed, probably reflecting different inputs and attenuation at various locations. Total DDT concentrations varied from <0.25 ng/g to 885 ng/g. The ratios of DDTs (2,40 - and 4,40 DDT)/total DDTs (DDTs plus metabolites) in sediment samples from certain sites were 0.86 or higher, indicating little attenuation or recent input of DDT. Total chlordane (the sum of heptachlor and its epoxide, oxy-, c- and a-chlordane and cis þ trans-nonachlor) ranged from <0.25 to 44 ng/g with the highest concentration found in the Arsenal Basin. The geographic distributions of PCBs, total DDTs and total chlordane were similar. Chlorinated benzenes (CBs), hexachlorocyclohexanes (HCHs), aldrin, dieldrin, endrin, chloropyrifos, endosulfan, mirex and pentachloroanisole were below detection limits or detected at low concentrations in most of the samples. Sites that were contaminated with high concentrations of organochlorine compounds were associated with dense population and low energy environment. The contamination levels of PCBs, total DDTs and total chlordane were in high range compared to other locations worldwide. Ó 2002 Elsevier Science Ltd. All rights reserved. Keywords: Organochlorine pesticides; PCBs; Marine sediments; Persistent organic pollutants; Alexandria Harbour, Egypt
Coastal sediments act as temporary or long-term sinks for many classes of anthropogenic contaminants. Organochlorines (OCs), such as polychlorinated biphenyls (PCBs) and chlorinated pesticides, represent an important group of persistent organic pollutants (POPs) that have caused worldwide concern as toxic environ-
*
Corresponding author. Tel.: +20-354-63250; fax: +20-354-63305. E-mail address: [email protected] (A.O. Barakat).
mental contaminants (Bildeman and Olney, 1974; Tanabe et al., 1982; Wade et al., 1988; Iwata et al., 1994; Allen-Gil et al., 1998; Wu et al., 1999). Many POPs are believed to be possible carcinogens or mutagens and are of considerable concern to human and environmental health. Although most of these compounds are no longer in use, the persistence of many OC compounds in the environment has prompted continued studies aimed at evaluating environmental quality for wildlife and humans (e.g., Wade et al., 1998).
Baseline / Marine Pollution Bulletin 44 (2002) 1421–1434
Studies on the environmental health of Alexandria Harbour have concentrated in the past mostly on simple chemical and bulk analysis of sediments and water (ElSayed et al., 1988; EA-ESTI, 1997). Few studies on the status of persistent organic contaminants in the coastal areas in Egypt have been conducted (Abdallah, 1992; Abdallah and Abbas, 1994). Alexandria Harbour plays important roles in both commercial activities for the economic development of Egypt and as an ecosystem to nurture coastal marine life. However, there is limited information available on the status of POPs in this important ecosystem. The Alexandria Harbour provides shelter from the open sea (Mediterranean Sea) giving rise to its use as a natural marina (Fig. 1). The narrow harbour entrance and the limited tidal range have made the harbour a lagoon-like enclosure. The rapid development of the Alexandria Harbour in the last few years and the continued increase in commercial and industrial activities within the harbour exert additional stress. The water quality in the harbour is potentially impacted by
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wastewater disposal (both untreated sewage and industrial) which are currently discharged to the harbour and the Mediterranean Sea directly via El-Mex Pump Station and through numerous storm and combined sewer outfalls located within the harbour area. The harbour is also heavily influenced by agricultural run off from the El-Mahmoudiya and Noubaria canals. OC pesticides have been used substantially in Egypt for the control of agricultural pests. Although the usage of PCBs in Egypt is not known, the past use of these substances in transformers, electrical equipments, ship painting and other industrial has been common. The objectives of this investigation were to assess the occurrence and distribution of persistent OC pesticides and PCB residues in sediments of Alexandria Harbour and to evaluate their potential effects on aquatic organisms. Twenty three sediment samples were collected within the harbour (Fig. 1) to cover regions affected by intense activities, freshwater input, wastewater outfalls as well as relatively pristine areas. In addition, two reference
Fig. 1. Location map of surface sediment sampling stations in Alexandria Harbour, Egypt.
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sediment samples, collected from Stanley Bay and Montazah beach located along the coast of Alexandria city were analyzed with this sample set. Surface sediment samples were taken with an Ekman grab sampler. Collected samples were frozen on dry ice and transferred to the laboratory for processing. Sample preparation and analysis methods have been described in Wade et al. (1988). Briefly, about 10 g of freeze-dried sediment was Soxhlet-extracted with methylene chloride. Concentrated extracts were fractionated with alumina/silica gel (80–100 mesh) column chromatography. Target analytes were eluted from the column with 50 ml of pentane (aliphatic fraction) and 200 ml of 1:1 pentane–dichloromethane (aromatic/PCB/pesticide fraction). The fractions were then concentrated to 1 ml using Kuderna–Danish tubes heated in a water bath at 60 °C. The surrogates dibromooctafluorobiphenyl (DBOFB), PCB103, and PCB198 were added to the samples prior to extraction. The chlorinated pesticides and PCBs were analyzed by gas chromatography in the spitless mode using an electron capture detector (ECD). A 30 m 0:32 mm i.d. fused silica column with DB-5 bonded phase (JW Scientific, Inc.) provided component separations. The chromatographic conditions for the pesticide–PCB analysis were 100 °C for 1 min, then 5 °C min1 to 250 °C, hold for 1 min, and then 10 °C min1 to 300 °C and a final hold of 5 min. The internal standard, tetrachlorom-xylene (TCMX), was added prior to GC/ECD analysis to monitor the recovery of surrogate. A standard solution containing only PCBs was used to confirm the identification of each PCB congener. The QA/QC procedures included analysis of matrix spikes, duplicates, laboratory blanks and certified reference material (Wade and Cantillo, 1994). For data presentation all concentrations below the method detection limits were assigned a value of 0.25 ng/g (dry weight) as the estimated average detection limit. The instrument was calibrated by injection of the standards component mixture at five different concentrations, prior to analysis of the samples. The following compounds were included in this study: 2,40 -DDT (2,40 -dichloro-diphenyltrichloroethane), 4,40 DDT and their degradation products 2,40 -DDD (2,40 dichloro-diphenyldichloroethane), 4,40 -DDD, 2,40 -DDE (2,40 -dichlorodiphenyltrichloroethene) and 4,40 -DDE, chlordane related compounds, chlorinated benzenes (CBs), hexachlorocyclohexanes (HCHs), aldrin, dieldrin, endrin, chloropyrifos, endosulfan, mirex and pentachloroanisole. For simplicity, the following nomenclature will be used in this paper: DDTs for the sum of 2,40 - and 4,40 DDT; DDDs for the sum of 2,40 - and 4,40 -DDD; DDEs for the sum of 2,40 - and 4,40 -DDE; total DDTs for the sum of DDTs, DDDs, and DDEs; total chlordane for the sum of heptachlor and its epoxide, oxy-, c, and achlordane, and cis- and trans-nonachlor; CBs for the sum
of 1,2,4,5- and 1,2,3,4-tetrachlorobenzene (TCB), pentachlorobenzene (PeCB) and hexachlorobenzene (HCB); HCHs for the sum of a-,b-, c-, and d-hexachlorohexane. Furthermore, the sum of 99 individual PCB congeners will be referred to as PCBs. PCBs concentrations in the sediments ranged from 0.9 to 1210 ng/g with a median of 260 ng/g (Table 1). The 21 harbour sites had PCBs levels higher than 37 ng/ g. The reference sites and the remaining open water sites had PCBs concentrations between 0.9 and 2.8 ng/g. Highest concentrations of PCBs were found in samples collected from enclosed vessel anchorage basins within the inner harbour (stations 1–9, Fig. 1). PCBs in samples collected from the inner harbour in the Arsenal Basin (1210 ng/g; station 1) and near El-Mahmoudiya Quay (556 and 477; stations 8 and 6, respectively) were among the highest sediment PCBs concentrations. These locations also had high concentrations of heavy metals and butyltin compounds (Barakat et al., 2001). Concentrations of PCBs in samples collected from enclosed bays and ship docking facilities in the Outer Harbour were also high. Two sites (stations 12 and 14) near a ship building facility close to Coal Quay had PCBs concentrations of 479 and 410 ng/g, respectively. High PCBs concentrations were also found in samples from the Marine Ship Lift and Dry Dock Facilities (218 ng/g, station 10), and the Harbour Bank area (178 and 206 ng/g; stations 17 and 18, respectively). PCBs levels were lower in the open mooring and anchorage areas (97–152 ng/g; sites 13, 15, and 16, Fig. 1) and ship channels (63–109 ng/g; sites 11, 20 and 21) where heavy traffic of tankers and commercial cargo boats are common. PCBs concentrations were low in open areas outside the harbour (0.9 and 2.8 ng/g, stations 22 and 23, respectively). The spatial distribution pattern of PCBs indicates that PCB contamination may have been associated with local ship activities and wastewater effluent outfall areas. The high concentrations of PCBs at station 1 in the Arsenal Basin were probably attributed to the operations of boat repairing facilities of Alexandria Company, including ship repainting, engine overhaul, and maintenance operations. This site is also located near large outfalls of storm water and domestic and industrial wastewaters. The Arsenal Basin is a semi-enclosed embayment with limited water exchange with the open sea. This may contribute to the accumulation of persistent contaminants in this basin. Similarly, the high concentrations of PCBs at stations near El-Mahmoudiya Quay may result from outflows from ElMahmoudiya Canal (Fig. 1). In addition, there were several local wastewater discharges to this area. Persistence of PCBs in aquatic sediments is due to their low rate of degradation and vaporization, low water solubility, and partitioning to particles and organic carbon (Kennish, 1992). The physicochemical
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Table 1 Concentrations (ng/g, dry wt) of PCBs and chlorinated pesticides in sediments of Alexandria Harbour, Egypt P Station Sample location PCBsa DDTsb Chlordanec HCBsd CHse Aldrin Dieldrin Endrin no. 1 2 3 4 5 6 7 8 9 10
11 12 13 14 15 16
17 18 19 20 21 22 23 Ref. 1 Ref. 2
Arsenal Basin Arsenal Basin Arsenal Basin Boathouse El-Mahmudiya Quay El-Mahmudiya Quay El-Mahmudiya Quay El-Mahmudiya Quay Ship Pass (inner harbour) Marine Ship Lift and floating dry dock Ship Pass (outer harbor) Coal Quay Coal Basin Shipyard/ Mooring Area Shipyard/ Mooring Area Mina El-Qamariya (Timber Wharves) Harbour Bank Mooring Area Petroleum Harbor Harbor Inlet (inside harbor) Harbor Inlet (outside harbor) Ship Pass (open sea) Ship Pass (open sea) Montazah Beach Stanley Bay
Chloropyrifos
Mirex
Endosulfan
1211 114 280 349 339
885 21 189 27 58
44 8.7 12 9.3 7.6
2.4 0.5 1.5 2.9
0.8 0.4 0.8 0.9 0.3
13 1.5 7.9 1.2
0.4
22 2.1 1.8 5.8
477
23
4.6
3.3
22
274
40
4.8
0.9
3.9
1.2
556
203
29
6.0
4.6
3.1
6.7
51
203
36
1.8
0.3
0.4
0.4
1.0
218
34
1.3
1.2
2.1
1.1
0.9
92
10
1.4
0.6
1.1
0.1
479 128 410
66 58 119
3.8 2.1 4.0
0.5 0.7 0.9
1.4 1.3 0.9
1.4 0.8
0.7
152
29
2.2
1.7
0.6
0.4
3.5
98
15
1.0
0.9
0.5
0.3
0.4
178 206 37
30 97 13
1.9 2.1 0.3
1.0 2.5 0.4
0.7 1.1
0.7 1.5
109
27
1.0
1.1
0.4
2.3
63
8.9
1.2
0.6
0.9
0.3
2.8
0.7
1.0 0.9
a
PCB represent the sum of over 96 detected congeners. DDT is the sum of 2,40 + 4; 40 forms of DDT and its breakdown products, 2,4 + 4,40 -DDE and DDD. Concentrations of high DDTs were confirmed with a gas chromatography/mass spectrometry analysis of the samples with high DDT concentrations. c Chlordane is the sum of heptachlor and its epoxide, oxy-, c, and a-chlordane, cis- and trans-nonachlor. d CB is the sum of 1,2,4,5- and 1,2,3,4-TCB, PeCB and HCB. e HCH is the sum of a-, b-, c-, and d-hexaachlorohexane. f
properties as well as the degradation of PCBs vary widely and depend on the number and position of chlorine atoms in the biphenyl rings (Reutergarth, 1980; Abramowicz et al., 1993; Rhee et al., 1993). The PCB congeners identified in sediments of this study were predominantly tetra- to hepta-chlorinated biphenyls (Fig. 2). The most abundant PCB congeners detected in these sediment samples were PCB153/132 and PCB138/160
which are commonly found in environmental samples. Concentrations of PCB136, PCB180, PCB118, PCB107, PCB110, PCB170, PCB190, PCB187, PCB149 and PCB123 were at intermediate concentration levels. The latter PCB congeners have low to medium toxicity (Fernandez et al., 1999). The more toxic PCB congeners, such as PCB77, PCB81, PCB194, PCB126, PCB169 and PCB105, were present at low concentrations in these samples (Figs. 2 and 3).
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Fig. 2. Concentrations of PCBs represented as chlorination levels in Alexandria Harbour sediments.
Although the observed trends in PCB congeners composition were similar in some of the samples (e.g. between S-1 and S-3, and between S-5, S-7 and S-10, Fig. 3) the distribution patterns are, in general, different among the sediments of this study area (Fig. 3), which may indicate different input sources. The usage of PCB in Egypt is not well established, but the use of PCBs in transformers, electrical equipment, and other industries is common. The results from this study suggest that, owing to their persistence, PCBs contamination are widespread at Alexandria Harbour. Concentrations of total DDTs varied from <0.25 to 885 ng/g (dry weight) with a median concentration of 87 92 ng/g (Table 1). DDTs (2; 40 þ 4; 40 -DDT) and/or their breakdown products were detected in all of the samples inside the harbour. Samples from stations 22 and 23, which are located in outside the harbour (Fig. 1), and reference samples contained no detectable DDTs. Similar to PCBs, high concentrations of total DDTs were encountered at locations within the inner harbour and at sites located near ship activities and storm sewer outfalls (stations 1, 3, 8, 14 and 18; 100–885 ng/g). Other sites with elevated concentrations of total DDTs (58–66 ng/g) are stations 5, 12, and 13. The total DDTs concentrations were in the range from 10 to 40 ng/g (average of 26 7 ng/g) in the remaining samples. The high concentrations of total DDTs and related compounds in these sediments indicate that DDT usage was heavy and the harbour has received significant inputs of DDTs. DDTs undergoes degradation to DDDs and DDEs in natural environment by chemical and biological processes (Wedemeyer, 1967; Baxtor, 1990). Fig. 4 shows DDTs and their metabolites as a percentage of total DDTs at the different sampling sites. Over 85% of the total DDTs in sediments from stations 1, 3, and 6 was
present as DDTs and particularly as 2,40 -DDT. The dominance of DDTs in the sediment indicates slow degradation of DDTs or recent inputs of fresh DDT at these locations (Tavares et al., 1999; Yuan et al., 2001). Station 12 also showed significant concentrations of DDTs (38%). DDDs and DDEs were predominant in the remaining samples, with DDDs and DDEs representing over 75% of total DDTs. DDTs were, therefore, not newly released into those locations and were mainly present as metabolites. DDDs accounted for the majority of DDT related compounds at these locations (Fig. 4). The dominance of DDDs over DDEs in these sediments indicates reductive dechlorination of DDTs to DDDs under anaerobic conditions (Wedemeyer, 1967; Baxtor, 1990). This observation is in agreement with the fact that Alexandria Harbour is a semi-closed bay with restricted water exchange with the open ocean and the sediments were anoxic. DDT was widely used in Egypt on a variety of agricultural crops and for the control of disease vectors. The largest agricultural use of DDT has been on cotton, which accounted for more than 80% of the use before its ban. Although its usage was banned in 1988, its detection, along with detection of its breakdown products (i.e., DDEs þ DDDs), in sediments is expected because the reported environmental half-life of DDTs is estimated as 10–20 years (Woodwell et al., 1971; Sericano et al., 1990). Sediment concentrations of total chlordane ranged from <0.25 to 44 ng/g (dry weight) with a median concentration of 6 ng/g (Table 1). a-Chlordane was the major chlordane isomer in all the samples. This is expected since a-chlordane is one of the main components of technical grade chlordane (Dearth and Hites, 1991). Similar to the distribution of DDT and its metabolites,
Baseline / Marine Pollution Bulletin 44 (2002) 1421–1434
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Fig. 3. Relative abundance of selected PCB congeners having the highest average concentrations in representative sediment samples from Alexandria Harbour.
high concentrations of total chlordane were encountered in the inner harbour area (Stations 1–8, Fig. 1) with the highest residue concentrations (44 ng/g) found at station 1 in the Arsenal Basin. These sites in the inner harbour also had the highest concentrations of total PCBs and total DDTs. In contrast to stations 1–8, chlordane concentrations at the remaining sites in the outer harbour area were low (less than 4 ng/g), indicating that the contamination of sediments in the outer Alexandria Harbour by chlordane related compounds was minimal. In addition, chlordanes were not detected at stations 22 and 23 and the reference stations.
The CBs, such as 1,2,4,5-TCB, 1,2,3,4-TCB, and PeCB, may be metabolites of the commercial pesticide HCB or other CBs, e.g. pentachlorophenol (Wang and Jones, 1994). The concentrations of these CBs and HCH were either below detection limits or low (Table 1). Highest concentrations of chloropyrifos and endosulfan II were found in the inner harbour region. Chloropyrifos (<0.25–51) was detected in 26% of the samples with highest levels at station 8, while endosulfan II (<0.25–22) was detected in 44% of the samples with highest concentrations at the Arsenal basin (station 1). Chloropyrifosis highly toxic to molluscs, fish and
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Fig. 4. Percentage of total DDTs represented by DDTs and their metabolites DDDs and DDEs in sediments from Alexandria Harbour.
crustaceans (Briggs, 1992) and it has been reported in Biota samples (Pait et al., 1992). Endosulfan was reported to be responsible for more fish deaths in US estuaries and coastal areas between 1980 and 1989 than any currently used pesticide and was ranked as the most hazardous of the currently used pesticides considered (Pait et al., 1992). Aldrin, dieldrin and endrin were found at low concentrations in several samples, with highest results found in sediments near El-Mahmoudiya Quay stations (stations 5, 7 and 8, Table 1). Aldrin (<0.25–4.6 ng/g) was
detected in 30% of the samples analyzed, dieldrin (<0.25–3.1 ng/g) in 35% samples and endrin (<0.25–6.7 ng/g) in 39% samples. Other OC pesticides such as mirex and pentachloroanisole were near or below the method detection limit. Long et al. (1995) conducted an extensive review of articles that provide both concentrations of contaminants in sediment and observed biological effects. They derived consensus values by considering data from all of the studies reviewed and ranked from low to high. A 10th and 50th percentile were then determined and were designated effects range low (ER-L) and effects range median (ER-M). The ER-L and ER-M values for total DDT are 3 and 350 ng/g, for PCBs are 50 and 400 ng/g, and for chlordanes are 0.5 and 6 ng/g, respectively. Total PCB concentrations in the sediments from nearly all the sites except for the reference sites and the two sites located in the open ocean were above the ER-L value and the total PCB concentrations in the samples from five sites (stations 1, 6, 8, 12, and 14) were above the ER-M value that could elicit toxic response for most benthic organism. In addition, the DDT concentrations in samples from all the sites except for the reference sites and sample from the open ocean (station 22 and 23) were above the ER-L value (Table 1). Chlordane concentration exceeded the ER-M at six sites and ER-L at 13 sites. Dieldrin and Endrin concentrations exceeded
Table 2 Comparison of PCB and OC pesticide concentrations (ng/g dry wt) in the sediments from other locations Location
Year
PCBs
Total DDT
Chlordane
HCHs
References
Mediterranean Sea Northwest Basin Open sea
1990 1983
1.4–5.8 0.8
1.2–5.8 0.047
NA NA
NA 0.18a
Tolosa et al. (1995) Burns and Villeneuve (1987)
Coastal Barcelona Offshore Casco Bay, Maine, USA Abu-Quir Bay, Egypt
1990 1991 1989–1991
4.0–64 0.4–485 53–231
4.9–79 <0.2–20 44–223
NA <0.25–4.91 NA
NA <0.07–0.48a 16–82
El-Mex Bay, Egypt
1989–1991
68–164
32.3–87
NA
16–53
Tolosa et al. (1995) Kennicutt et al. (1994) Abdallah (1992), Abdallah and Abbas (1994) Abdallah (1992); Abdallah and Abbas (1994)
Rivers, lakes, estuaries Ebro River, Spain Ebro Prodelta, Spain Rhone Prodelta, France Lake Baikal, Russia Washington, DC, USA Hong Kong, PRC Chinese river/estuaries systems
1995–1996 1990 1990 1992 1991 1997–1998 1996–1998
5.3–1772 1.6–39 38–230 0.08–6.1 68–3200 0.48–97.9 0.05–20
0.4–52 0.8–93 73–704 0.014–2.7 7–160 0.27–14.8 0.1–71
NA NA NA n.d.–0.003 5–153 n.d.–11.3 NA
0.001–0.038 NA NA 0.019–0.12 NA 0.1–16.7 0.2–101
Fernandez et al. (1999) Tolosa et al. (1995) Tolosa et al. (1995) Iwata et al. (1995) Wade et al. (1994) Richardson and Zheng (1999) Hong et al. (1999), Wu et al. (1999), Yuan et al. (2001)
1992 1993
3.2–27 0.05–7.2 0.5–14.2 0.9–1211
1.4–30 4.5–311 1.2–2.3 <0.25–885
NA NA 0.9–5.3 <0.25–44
n.d.–2.3 0.14–1.12 0.1–2.0 0.25–6.0
Connell et al. (1998) Hong et al. (1995) Fox et al. (1988) This study
Harbours Victoria Harbour, Hong Kong Xiamen Harbour, PRC Manukkau Harbour, New Zealand Alexandria Harbour, Egypt NA: no data available. n.d.: not detected. a Reported as c-lindane.
1998
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the ER-L at eight and nine sites, respectively. The high concentrations of PCBs, DDTs, chlordane, dieldrin and endrin in the sediments of Alexandria Harbour, therefore, could cause detrimental biological effects for the benthic organisms (Long and Morgan, 1990). Compared to concentrations reported in coastal environments from other parts of the world, PCB concentrations in surface sediments of Alexandria Harbour were one to two orders of magnitude higher than most of the riverine/estuaries systems (Table 2). However, the concentration of total PCBs in the severely impacted areas from the US and Spain were higher than the Alexandria Harbour area. Similarly, concentrations of total DDT were higher than other harbours and riverine/estuary systems except in some severely contaminated locations, such as in the NW Mediterranean sediments from the Rhone Prodelta, Spain. (Table 2). Chlordane concentrations were also higher than those reported from other locations except for the sediments from Washington, DC area. In comparison, the contamination of sediments in the Alexandria Harbour by PCBs, DDTs and chlordanes appeared to be high on a worldwide basis. In order to determine the sources of the observed contaminants, intense localized sampling and analysis of effluents and runoff patterns would be needed. To determine sediments quality, bioassays of sediments at suspected sites should be conducted to directly assess the potential for biological impacts.
Acknowledgements Analytical support by the laboratory staff at Geochemical and Environmental Research Group, Texas AM University is appreciated. We thank Dr. A.R. Mostafa for help during the sampling activities. A.O. Barakat is grateful to the Fulbright Foundation for a research fellowship.
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