Baseline

Edited by Bruce J. Richardson

The objective of BASELINE is to publish short communications on different aspects of pollution of the marineenvironment. Only those papers which clearly identify the quality of the data will be considered for publication.

Contributors to Baseline should refer to ‘Baseline—The New Format and Content’ (Mar. Pollut. Bull. 42, 703–704).

PAH contamination of western Irish Sea sediments

M. Charlesworth a,*, M. Service b, C.E. Gibson b

a Department of Agriculture and Environmental Science, The Queens University of Belfast, Newforge Lane, Belfast BT9 5PX, Northern Ireland, UKb Agricultural and Environmental Science Division, Department of Agriculture and Rural Development for Northern Ireland,

Newforge Lane, Belfast BT9 5PX, Northern Ireland, UK

Abstract

Concentrations of the sum of 15 PAHs in 22 surficial sediment samples from the western Irish Sea ranged from below 100 ng g�1

in sandy sediments to a maximum of 1422 ng g�1 in the centre of the mud basin. The concentrations are typical of coastal shelfsediments, but greater than those observed for aquatic sediments remote from known anthropogenic sources. Organic C and the %

sediment <15 lm were positively correlated with RPAH. RPAH was normalised to organic C and particle size (i.e. expressed as

RPAH/Corg and RPAH/%<15 lm) and significant relationships were still observed with organic C and %<15 lm. The results arediscussed in the context of using organic C to normalise concentrations of PAHs to assess contamination levels in sediments.

� 2002 Elsevier Science Ltd. All rights reserved.

Keywords: PAHs; Sediments; Western Irish Sea; Normalisation

Previous research on polycyclic aromatic hydrocar-

bons (PAHs) in subtidal sediments of the Irish Sea has

been limited to the eastern side (Law, 1981; Law et al.,

1989; Woodhead et al., 1999) and two northern Irish Sea

loughs (Guinan et al., 2001). To our knowledge there areno comprehensive studies of PAHs in subtidal sediments

of the western Irish Sea despite PAHs being identified as

an issue of importance in a recent review of the Irish Sea

because of their toxicity (DETR, 2000). Widdows et al.

(2002) demonstrated that Mytilus edulis collected from

intertidal shores had a higher physiological stress re-

sponse (reduced scope for growth) within the Irish Sea

compared to samples collected from clean reference sites

of other UK and Irish coasts. At the majority of sites

within the Irish Sea, 50% to >80% of the reduced scopefor growth could be attributed to PAHs causing a re-

duction of mussel feeding rate. The western Irish Sea

gyre which is present in spring and summer may act as atrap for contaminants (Hill et al., 1997) which in com-

bination with the depositional environment of the

western mud basin (Mitchell et al., 1999; Charlesworth

et al., 2002) suggests that the area may act as a sink for

contaminants. It was the intention of this work to pro-

vide data on PAHs in sediments of the western Irish Sea

and relate this to organic carbon and particle size

characteristics.A total of 22 surface sediment samples were collected

by Day Grab on board the RV Lough Foyle in June and

July 2000 (Fig. 1). Sediment was taken from the surface

of the grab to a depth of 1 cm in a pre-solvent rinsed

*Corresponding author. Tel.: +44-28-9025-5490; fax: +44-28-9038-

2244.

E-mail address: m.charlesworth@qub.ac.uk (M. Charlesworth).

www.elsevier.com/locate/marpolbul

Marine Pollution Bulletin 44 (2002) 1421–1434

glass honey jar, capped with a pentane rinsed foil cap

liner and frozen until further processing. A separate

sample was taken for particle size analysis. Following

removal of sediment for PAH analysis, samples were

freeze-dried and a representative sub-sample taken for

organic C determination. Organic carbon content was

determined using an elemental analyser (model NA1500, Carlo Erba Instruments, Milan, Italy) after

treatment with sulphurous acid to remove inorganic

carbon. Particle size analysis was conducted by laser

granulometry (Mastersizer/E, Malvern Instruments)

following treatment with 0.1% Calgon overnight and

dispersion in an ultrasonic bath for 10 minutes. Particle

size results were then summarised using the graphical

methods of Folk (1974). Methods for PAH analysishave been previously reported by Kelly et al. (2000) and

are only briefly described here. Wet sediments were ex-

tracted using alkaline saponification. A sub-sample was

taken to calculate the % dry weight on which basis all

the results are reported. Deuterated PAHs (naphtha-

lene-d8, anthracene-d10, pyrene-d10 and perylene-d12)

were added to the samples at the beginning of the

procedure to allow recoveries to be calculated. Digestswere filtered and extracted with pentane, and dried over

previously roasted NaSO4. The extract was reduced to

approximately 1 ml and passed through columns of 5%

activated alumina. Extracts were then adjusted to fall

within the linear range of PAH standards and an in-

ternal volumetric standard added. GC–MS analysis for

a range of PAHs is as described by Guinan et al. (2001).

Chrysene and triphenylene co-eluted and are reportedtogether. The compounds indeno[1,2,3-cd]pyrene and

dibenzo[a; h]anthracene separated but not sufficiently to

get an integration of reproducible peaks and thereforeion chromatograms were difficult to resolve as the mo-

lecular ion in indeno[1,2,3-cd]pyrene was also a signifi-

cant ion in the spectrum for dibenzo[a; h]anthracene.Mean recoveries of naphthalene-d8, anthracene-d10,

pyrene-d10 and perylene-d12 were 39� 8%, 71� 4%,73� 3% and 69� 4%, respectively which are within therange reported elsewhere for PAH analysis of sediments

(Fernandes and Sicre, 1999; Mitra et al., 1999; Guinanet al., 2001). Concentrations of PAHs were adjusted

according to the recovery of the deuterated PAHs with

the same number of benzene rings. Blanks and Certified

Reference Material HS-4B (National Research Council

Canada) were routinely analysed alongside PAH sam-

ples. In addition, the laboratory participates in the

QUASIMEME (Quality Assurance of Information for

Marine Environmental Monitoring in Europe) profi-ciency scheme for PAHs. Linear regression analysis was

performed using the software package Statgraphics Plus

version 2.0.

PAH and Corg concentrations, and particle size

characteristics are detailed in Table 1. The mean grain

sizes of the sediments range from very fine silt to me-

dium sand. The %<63 lm (silt and clay) reflects that ofthe mean grain size with >84% <63 lm at 10 stations inthe centre of the mud basin. Sediments get progressively

coarser towards the edge of the study area. Organic

carbon ranges between 0.1 and 2.9%. Concentrations

are generally highest in the centre of the mud basin

between 1.5% and 1.8% decreasing towards the periph-

ery of the study area. The exception to this is the high

concentrations found in the coarse sediments at stations

7 and 12 near to the south coast of the Isle of Man. Thiswas observed previously (Charlesworth et al., 1999), but

is difficult to explain in relation to the productivity,

sediment type and hydrography of the region. All PAHs

correlate with each other with an r2 of >0.96 at a sig-nificance level of >95% suggesting a common source,

therefore the distribution ofPPAH may be used as

indicative of individual compounds. The highest con-

centrations ofPPAH are found at four stations in the

centre of the mud basin (between 1295 and 1422 ng g�1)Concentrations decrease to below 100 ng g�1

PPAH

towards the edge of the area in the coarser sediments.

The range of PAH concentrations is typical of what

has been recorded in other Northern Irish coastal sedi-

ments away from the direct influence of point sources

(Guinan et al., 2001). Comparison with other studies is

confounded by other authors using the sum of differentcompounds to calculate

PPAH. However, a compari-

son of individual compounds suggests that the levels of

PAHs are within the same range reported by Law et al.

(1989) for samples from the eastern Irish Sea, and other

coastal sites in UK and Ireland (Woodhead et al., 1999).

Remote lakes and offshore sediments may be used to

compare concentrations to those distant from known

Fig. 1. Location of sampling sites in the western Irish Sea.

1422 Baseline / Marine Pollution Bulletin 44 (2002) 1421–1434

Table 1

PAH concentrations (ng g�1) and physical characteristics of sediments from the western Irish Seaa

Nos. Naph Fluo Phe Anth Fluor Pyr BaA Chrþ Tri BeP BaP Per IndþDiB BPerPPAH Corg (%) Mz %<63 lm %<15 lm

1 17 7 28 6 35 27 18 26 29 24 8 39 52 316 1.5 3.9 44 32

2 46 16 68 14 90 66 47 68 71 59 19 82 128 776 1.5 6.1 73 50

3 52 18 78 15 102 74 54 78 86 68 22 88 152 887 1.2 6.6 84 61

4 77 27 123 23 156 117 88 123 141 113 35 145 254 1422 1.7 7.4 98 77

5 39 15 68 15 99 80 55 67 81 72 22 83 146 844 1.2 6.4 86 53

6 8 2 8 2 6 5 4 5 6 5 2 6 10 66 1.7 3.0 38 33

7 48 13 59 11 76 54 41 64 73 54 17 75 130 715 1.0 5.6 65 57

8 77 23 102 20 138 95 77 119 133 97 31 140 243 1296 1.7 7.5 98 81

9 66 22 100 20 143 103 83 110 139 109 31 148 264 1339 1.6 7.5 99 81

10 10 2 7 2 10 8 6 7 9 8 3 9 16 98 0.4 4.2 37 29

11 8 2 4 1 4 3 3 3 3 3 1 3 5 42 2.9 2.7 25 20

12 11 2 6 2 8 5 4 6 7 5 2 9 10 77 0.9 3.4 39 32

13 52 16 63 14 91 61 46 71 74 57 22 96 129 791 1.2 6.4 88 54

14 87 28 114 24 151 101 81 131 141 103 33 162 252 1409 1.8 7.8 99 85

15 46 14 63 14 92 67 51 69 88 69 23 100 164 860 1.3 7.2 97 70

16 17 4 15 5 23 18 13 16 18 16 6 19 30 200 0.5 4.0 39 38

17 24 6 25 6 31 21 16 25 23 19 9 29 38 271 0.9 4.8 46 30

18 71 22 88 20 126 82 62 103 102 78 29 124 177 1084 1.5 7.1 97 71

19 65 20 87 19 124 82 65 101 110 82 28 127 197 1107 1.5 7.2 97 71

20 31 9 39 9 54 38 29 42 45 35 14 53 79 476 1.1 6.0 76 47

21 29 11 48 11 65 44 31 49 44 37 15 62 73 520 1.1 6.0 71 48

22 2 bdl bdl bdl bdl bdl bdl bdl bdl bdl bdl 1 bdl 3 0.1 2.4 21 10

a PAHs concentrations in ng g�1 dry weight. Naph: naphthalene, Fluo: fluorene, Phe: phenanthrene, Anth: anthracene, Fluor: fluoranthene, Pyr: pyrene, BaA: benzo[a]anthracene, Chr+Tri:

chrysene+ triphenylene, BeP: benzo[e]pyrene, BaP: benzo[a]pyrene, Per: perylene, Ind+DiB: indeno[1,2,3-cd]pyrene and dibenzo[a,h]anthracene, BPer: benzo[g,h,i]perylene, RPAH: sum PAHs,

Corg: % organic carbon, Mz: graphic mean grain size (phi), %<63 lm: % sediment <63 lm (silt and clay), %<15 lm: % sediment <15 lm, bdl: below detection limits.

Baselin

e/MarinePollutionBulletin

44(2002)1421–1434

1423

sources of contamination. The concentration of PAHs in

sediments of a remote lake in north-west Scotland (Roseand Rippey, 2002) and 12 European high altitude lakes

believed to be contaminated by atmospheric PAH

sources alone (Fernandez et al., 1999) are predominantly

lower than observed for the western Irish Sea. Ohkouchi

et al. (1999) reported lower concentrations in sediments

of the central Pacific than in this study region. Care must

be observed when comparing concentrations due to the

effects of organic C and grain size on PAH levels (Gu-inan et al., 2001; Yang, 2000) although the above dem-

onstrates that concentrations found in the western Irish

Sea are similar to those in other coastal shelf sediments,

and equal to or greater than those observed for aquatic

sediments remote from known anthropogenic sources.

Relationships are first investigated between grain size

and Corg prior to investigating the influence of these

parameters on PAHs. A linear regression between %<63lm (silt and clay) and Corg (Fig. 2a) shows that a sig-

nificant relationship is not observed if data from all

stations is used (n ¼ 22, r2 ¼ 0:10, p > 0:1). The lack of

relationship is in part caused by the high concentra-tions of Corg at stations 7 and 12 composed of course

sediments, that as previously discussed are anomalous to

the region. Fig. 2a also shows that concentrations of

Corg sediments with >97% <63 lm cannot be explainedby the grain size alone, as at this %<63 lm, Corg con-tinues to increase when %<63 lm is at a maximum. Thisimplies that it is a finer fraction of material than 63 lmthat is important in determining the Corg concentrations.If stations 7 and 12 are omitted and the Corg regressed

against a finer fraction of sediment (%<15 lm) (Fig. 2b)Corg explains 71% of the variation in Corg (n ¼ 20,p < 0:001).Fig. 3a shows that concentrations of

PPAHs below

1100 ng g�1 have a significant relationship with thefraction of sediment %<63 lm (n ¼ 22, r2 ¼ 0:90,p < 0:001), but above 1100 ng g�1

PPAH this fraction

of sediment cannot explain concentrations alone as also

observed for Corg. The full range ofPPAHs encoun-

tered shows a better relationship with the %<15 lmfraction (n ¼ 22, r2 ¼ 0:93, p < 0:001) (Fig. 3b) sug-

0

400

800

1200

1600

2000

0 20 40 60 80 100

%<63 µm

Sum

PAH

s (n

g g-1

)Su

m P

AHs

(ng

g-1)

(a)

0

400

800

1200

1600

2000

0 20 40 60 80 100

%<15 µm

(b)

Fig. 3. Relationship between (a)PPAHs and % sediment <63 lm, and

(b)PPAHs and % sediment <15 lm.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 20 40 60 80 100%<63 µm

(a)

0.0

0.3

0.6

0.9

1.2

1.5

1.8

2.1

0 20 40 60 80 100%<15 µm

Org

anic

C (%

)O

rgan

ic C

(%)

(b)

Fig. 2. Relationship between (a) Corg and % sediment <63 lm, and (b)Corg and % sediment <15 lm with stations 7 and 12 omitted.

1424 Baseline / Marine Pollution Bulletin 44 (2002) 1421–1434

gesting that it is this fraction of sediment that is mostimportant for explaining the concentration and thus

distribution of PAHs in the study area. Several authors

have shown that in contaminated sediments close to

known sources of anthropogenic inputs large particles

(>63 lm) may be important in determining PAH con-

centrations (Simpson et al., 1998; Ghosh et al., 2000;

Wang et al., 2001). However, in areas distant from direct

inputs, the fraction of sediment <63 lm or in the case ofthe western Irish Sea, the fraction <15 lm, is the mostimportant sediment fraction in determining the con-

centration and thus distribution of PAHs as observed

elsewhere (Maruya et al., 1996; Kim et al., 1999; Guinan

et al., 2001). Since a significant relationship exists be-

tween the % sediment <15 lm and Corg, a relationship isalso observed for Corg and

PPAHs once stations 7 and

12 are removed (n ¼ 20, r2 ¼ 0:74, p < 0:001). This is aweaker relationship than observed between

PPAHs

and %<15 lm suggesting that although Corg is also an

important factor that influences the concentration and

thus distribution ofPPAHs, the %<15 lm is the

dominant.

Surprisingly, if thePPAHs are normalised to %<15

lm or Corg (i.e. expressed as PAH/%<15 lm and PAH/Corg) and then regressed against Corg and %<15 lm,positive linear relationships are still observed (n ¼ 19,p < 0:005). Normalisation to either %<15 lm or Corg

can therefore not account for the distribution of PAHs

alone as observed by Maruya et al. (1996). The literature

also implies that difficulties exist using organic C to

normalise PAH concentrations in sediments. Firstly,

although PAHs may be associated with organic matter

in sediments, media such as soot which contribute onlysmall amounts of C to the total C are commonly more

important phases for PAHs. It is only when these

additional media are taken into account that the solid–

water distribution coefficients of PAHs may be ex-

plained (Gustafsson et al., 1997). Secondly, diverse

benthic communities can mask relationships between

PAHs and Corg (Guinan et al., 2001) which may cause

spurious PAH/Corg ratios. Lastly, different anthropo-genic sources of PAHs have a range of concentrations of

PAHs per gram of Corg (Page et al., 2000; Rogers, 2002).

Clearly, where a number of different sources contribute

to Corg and PAHs in sediments, using Corg to normalise

concentrations of PAHs to assess contamination levels

should be applied with care.

Acknowledgements

The authors would like to thank the officers and crew

of the RV Lough Foyle, P. Elliot and B. Stewart for

assistance with sample collection and S. Wilson for as-

sistance with laboratory analysis.

References

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0025-326X/02/$ - see front matter � 2002 Elsevier Science Ltd. All rights reserved.

PII: S0025-326X(02 )00306 -5

Organochlorine pesticides and PCB residues in sedimentsof Alexandria Harbour, Egypt

Assem O. Barakat a,*, Moonkoo Kim b, Yoarong Qian b, Terry L. Wade b

a Department of Environmental Sciences, Faculty of Science, Alexandria University, 21511 Moharrem Bey, Alexandria, Egyptb 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 cisþ trans-nonachlor)ranged from <0.25 to 44 ng/g with the highest concentration found in the Arsenal Basin. The geographic distributions of PCBs, totalDDTs 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.

� 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 biphe-

nyls (PCBs) and chlorinated pesticides, represent animportant group of persistent organic pollutants (POPs)

that have caused worldwide concern as toxic environ-

mental contaminants (Bildeman and Olney, 1974; Tan-

abe 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 areof 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).

*Corresponding author. Tel.: +20-354-63250; fax: +20-354-63305.

E-mail address: abarakat@dataxprs.com.eg (A.O. Barakat).

1426 Baseline / Marine Pollution Bulletin 44 (2002) 1421–1434