- Email: [email protected]
Polychlorinated biphenyls and cyclic pesticides in sediments and macro-invertebrates from the coastal zone and continental slope of Kenya
Marine Pollution Bulletin
mammals deal with high cadmium burdens may have significance for human medical treatment of cadmiuminduced renal degradation. Andr6, J.M., Ribeyre, F. and Boudou, A. (1990) Mercury contamination levels and distribution in tissues and organs of delphinids (Stenella attenuata) from the eastern tropical Pacific, in relation to biological and ecological factors. Marine Environmental Research, 30, 43-72. Dietz, R., Riget, F. and Johansen, P. (1996) Lead, cadmium, mercury and selenium in Greenland marine animals. The Science of the Total Environment, 186, 67-93. Dietz, R., Johansen, P., Riget, F. and Asmund, G. (1997) Heavy metals in the Greenland Marine Environment, National Assessment, ln: AMAP Greenland 1994-96, Arctic Monitoring and Assessment Programme (AMAP). Danish Environmental Protection Agency, Environmental Project, 356, 119-245. Dietz, R., Pacyna, J. and Thomas, D. J. (in press). Heavy metals. AMAP International Assessment, Arctic Monitoring and Assessment Programme, Oslo, Norway. Dragert, J., Corey, S. and Ronald, K. (1975) Anatomical aspects of the kidney of the harp seal Pagophilus groenlandicus (Erxleben, 1777). Rapport Process verbeaux R~union International Exploration de la Mer, 169, 133-140.
Marine PollutionBulletin, Vol. 36, No. 6, pp. 492-500, 1998 © 1998 Published by Elsevier Science Ltd. All rights reserved. Printed in Great Britain 0025-326X/98 $19.00+0.00
PII: 0025-326X(98)00029-0
Polychlorinated Biphenyls and Cyclic Pesticides in Sediments and Macro-invertebrates from the Coastal Zone and Continental Slope of Kenya J. M. EVERAARTS, E. M. VAN WEERLEE, C. V. FISCHERM and TH. J. HILLEBRAND Department of Marine Biogeochemistry and Toxicology, Netherlands Institute for Sea Research, PO Box 59, I 790 AB Den Burg, Texel, The Netherlands Over 70% of the Earth's surface consists of oceans, coastal seas and estuarine zones. The importance of marine ecosystems is also illustrated by the fact that the coastal area is inhabited by about 60% of the world's population. Thus, in particular, estuarine and coastal systems, showing considerable biological activity, are exposed to a high degree of contamination. The load of anthropogenic compounds induces impairment of various physiological functions of individual organisms and affects the ecological quality of ecosystems. Polychlorinated biphenyls (PCBs) and chlorinated pesticides (e.g. DDTs, dieldrin) show a global distribution. They are ubiquitous toxic contaminants, due to their bioaccumulative capacity and persistence and specific physico-chemical properties. Technical PCB mixtures or the individual CB congeners and pesticides accumulate in biota of all trophic levels and 492
Elinder, C.-G. and Jfirup, L. (1996) Cadmium exposure and health risks: recent findings. Ambio, 25, 370-373. Hansen, J.C., Toribara, T.Y. and Muhs, A.G. (1989) Trace metals in human and animal hair from the 15th century graves at Qilakitsoq compared with recent samples. Meddelelser om GrOnland, Man and Society, 12, 161-167. Law, R. J. (1996) Metals in marine mammals. In Environmental Contaminants in Wildlife. Interpreting Tissue Concentration, eds. W. N. Beyer, G. H. Heinz and A. W. Redmon-Norwood, pp. 357-376. SETAC Special Publication Series. CRC Press Inc., Lewis Publishers Inc., Boca Raton, FL. Loring, D.H. and Astound, G. (1996) Geochemical factors controlling accumulation of major and trace elements in Greenland coastal and fjord sediments. Environmental Geology, 28, 2-11. Nilsson, A. (1996) Arctic pollution issues: a state of the Arctic environment report. Arctic Monitoring and Assessment Programme, Oslo, Norway. Wagemann, R., Innins, S. and Richard, P. (1996) Overview and regional and temporal differences of heavy metals in Arctic and ringed seals in the Canadian Arctic. The Science of the Total Environment, 186, 41-66. WHO (1992) Cadmium. Environmental Health Criteria, Vol. 134. World Health Organization, Geneva.
residues are reported in environmental compartments from all geographical latitudes (Preston, 1988; Everaarts et al., 1993). However, from certain regions such as the South Pacific and the western Indian Ocean, contaminant levels in various environmental compartments were neither extensively investigated nor well reported. Only recently, data from these areas were published, indicating low levels of PCBs and DDTs in water and fish from an estuary on the east coast of South Africa (Grobler et al., 1996). Levels of PCBs and a wide variety of pesticides were determined just above their detection limit in sediments and shellfish from Vanuatu and Tonga (Harrison et al., 1996). Concentrations of a wide variety of organic compounds in the estuarine and coastal environment of the Fiji Islands were also found to be low (<10 ng g-1 dry weight), and it was suggested that organochlorine pesticides had undergone conversion reactions, particularly enhanced due to the tropical climatic conditions (Morrison et al., 1996). Research on marine pollution is a priority area within the research and monitoring programs of the Kenyan Marine Fisheries Institutes, and necessary for pollution management and decision making (Anon, 1991). Pollution studies in the marine environment of Kenya mainly focused on the estuarine and coastal zone in the vicinity of Mombasa (T. Williams et al., 1997). However, other coastal areas, such as the Sabaki and Tana river mouths are even more impacted by freshwater run-offs or riverine influences. To the author's knowledge, only one publication reports on residues of organochlorine pesticides in fish from the estuarine environment of Kenya (Mugachia et al., 1992), which were considered to be low. The present study contributes to knowledge on the status of the marine ecosystems along the coast of
Volume 36/Number 6/June 1998
locations and some of the hydrographic characteristics (salinity and temperature of bottom and surface water) have been published previously (Everaarts and Nieuwenhuize, 1995). Surface sediment samples were taken by means of sub-sampling the upper 5 mm layer of undisturbed sediment cores that were obtained with a Reineck box corer. From the sediments, approximately 20 g wet weight was wet extracted by vigorously mixing with a mixture of isopropanol, hexane and water, modified according to a rapid method of total lipid extraction and purification (Bligh and Dyer, 1959). The animal species, collected with a beam-trawl and a trawling time of 5-10 min, represented a number of
Kenya and its continental slope, in terms of the concentrations of anthropogenic lipid-associated cyclic halogenated hydrocarbons (PCBs, members of the DDT family, HCH-isomers and dieldrin) in sediment and selected benthic macroinvertebrates. Samples were obtained from the coastal zone and continental slope of Kenya (the Indian Ocean). Two surveys with the research vessel TYRO in 1992, from 18 June to 9 July (south-east monsoon), and from 19 November to 8 December (onset of the north-east monsoon) covered sampling locations in different areas of the coastal zone and along transects radiating into the Indian Ocean perpendicular to the Kenyan coast (Fig. 1). The geographic positions of the sampling 40 °
41°
I
,
42°
I
,
..
~;.
J"
I
.,ooO"
r .z °
20 < \ .t ~ o n o _ _
/
o=u" ~.~;.uBoy; ,.--(:-'" ,
.:.."
,. i
',
l"
.,...", , .o; For mos° Boy f
Y"
b
~
oo ,~
./
.u
./
.-/
I _ 3 °
SObok/
78/ Molindi
i.:"~910
/
•
12o
11
i3
,[oo " ~:--..,.,
2
_4 o
i l! /
o2
3o
I
4 0
p.t ~. -
IoO0
~zo.:. i.:,"
~g,
~'....."
", iI
o
o
4'oo
;lo
4'20
Fig. 1 Area of investigation in the estuarine and coastal zone and the continental slope of Kenya. Sampling sites are located along transects radiating into the Indian Ocean perpendicular to the Kenyan coast: Gazi transect (stations 1-4), Sabaki transect (stations 5-13), Tana transect (stations 14-17) and the Kiwayu transect (stations 18-22).
493
Marine Pollution Bulletin phyla (see below). About 3-5 g wet weight of whole body or specific tissue, measured to the nearest 0.01 g, was homogenized with as much anhydrous sodium sulphate (Na2SO4) necessary to obtain a dry-running mixture. Subsequently, the samples were Soxhlet extracted for 8h with 150ml of a 1:1 mixture of dichloromethane and pentane. The entire analytical procedure for chlorinated hydrocarbons, including sample extraction, clean-up, fractional separation of PCBs and most pesticides and pretreatment of the chemicals used, has been described earlier (Holden and Marsden, 1969; Duinker and Hillebrand, 1978, 1983; Everaarts et aI., 1993). Analyses of the samples were performed using a temperature-programmed gas chromatograph (Hewlett-Packard 5880a) equipped with a 60 m fused silica capillary column (0.15 mm diameter, 0.30 gm wall coating) with CP-SiI19 as stationary phase and a 63Ni-electron capture detector (ECD). Hydrogen was used as the carrier-gas at a pressure of 350 kPa and linear gas velocity of 30 cm min - 1. The temperature of the injector and detector was 230 and 340°C, respectively. Split-splitless injections of 1 ~tl aliquots of each sample dissolved in 2,2',4-trimethylpentane were made with an autosampler (HP 7673A). The temperature programme consisted of isothermal phases at 90°C (4.5 min.), 215°C (25 min.) and 270°C (20 min.), with intermediate temperature increase of 10 and 5°C min 1, respectively. For the identification and quantification of the biphenyl congeners, a synthetic mixture of 44 individual congeners was employed, and CBll2 as an internal standard. The congeners determined and reported here were the seven CB-congeners being selected in several countries as indicators, the quantitation of which may be used to determine whether PCB levels in food products, waste mineral oil and environmental samples comply with the maximum levels permitted by legislation (Anon, 1984, 1988; Wells et al., 1988; De Boer and Dao, 1991). These congeners, given in sequence of elution in the chromatogram, are CB28 (2,4,4'-tri-CB), CB52 (2,2',5,5'-tetra-CB), CB101 (2,2',4,5,5'-pentaCB), CBll8 (2,3',4,4',5-penta-CB), CB153 (2,2',4,4',5,5'-hexa-CB), CB138 (2,2',3,4,4',5'-hexa-CB) and CB180 (2,2',3,4,4',5,5'-hepta-CB). These represent different levels of overall chlorination of the molecule and also differ in the site of the chloro-atom substitution to the biphenyl skeleton. The numbering of the congeners is shown according to IUPAC rules, as suggested by Ballschmiter and Zell (1980). Apart from these, a number of other congeners were considered whose environmental occurrence is well established and which appeared as well separated peaks in the chromatogram from the CP-Sill9, such as the tri-CBs 18, 15, 26, 31, the tetra-CBs 49, 44, 74, the penta-CBs 99, 97, the hexa-CBs 136, 149, 141, 128, the hepta-CBs 187, 183, 177, 170, the octa-CBs 194, 195, and the deca-CB209 (Schulz et al., 1989). Additionally the 494
non-ortho chlorinated congeners CB77 and CB126, and
the mono-ortho chlorinated CB101 and CB105 were considered. The environmental concentrations of these congeners are generally low, but are considered to be the most toxic. The pesticides ~- and 7-hexachlorocyclohexane (HCHs), dieldrin, endrin and DDT-family members (p,p'-DDT, o,p'-DDT, p,p'-DDD, o,p'-DDD and p,p'-DDE), were identified and quantified on the basis of a synthetic mixture of these compounds, using CB155 as internal standard. The standards were injected every 10th injection for recalibration of the retention time and the response factor of each compound. The response factor of each peak in the standard mixture representing either a CB congener or pesticide, did not differ more than 10% between successive analyses of the standards. A peak in a chromatogram of a sample was only assigned to a compound in the standard mixture when its retention time did not differ more than 0.025 rain. from that compound in the standard. For a positive identification, the peak pattern in the chromatogram was also taken into account. A compound was considered non-detectable (limit of detection; LOD) when the peak height was less than the value of the average of the analyte blank signals, plus three times the standard deviation of the blank (SDb). Peak heights with a value of the average of the analyte blank signals, plus three to nine times SDb, or plus above nine times the SDb, were considered as being identifiable only or appropriate for quantification (limit of quantification; LOQ), respectively. To control procedural blank levels, each series of five samples was accompanied alternately by a blank run of pure Na2SO4 and a complete analytical procedure with sewage sludge or cod-liver oil, being Certified Reference Material of the CEC Bureau for Certified Reference materials CRM392 or CRM349, respectively. The certified and measured values for the selected CB congeners 28, 52, 101, 118, 153, 138 and 180 are summarized in Table 1. All analytical steps and procedures were performed according to formalized Standard Operating Procedures and were undertaken in the framework of the intercalibration exercises of the EC program QUASIMEME, Quality Assurance of Information for Marine Environmental Monitoring in Europe. The analytical results achieved by the organic-analytical laboratory of the Netherlands Institute of Sea Research (serving as reference laboratory) were excellent (cf. De Boer and Wells, 1996). The concentrations (expressed on the basis of organic carbon, OC) of seven selected CB congeners and cyclic organochlorine pesticides in surface sediment and the content of total particulate organic carbon are presented in Table 2. In Kenyan coastal and offshore areas, CB congeners could be quantified (chromatograms also showing the specific PCB pattern)
Volume 36/Number 6/June 1998 TABLE 1
Certified and measured values of chlorobiphenylcongeners 28, 52, 101, 118, 153 and 180 in sewage sludge and cod-liver oil, CRM 392 (three analyses) and CRM 349 (five analyses), respectively, of the European Bureau for Certified Reference materials. Concentrations __+ standard deviation are expressedin ng g ~dry weight for sewage sludge and in ng g 1 extracted lipid for cod-liveroil
Sewage sludge (CRM392) Certified value Measured value Cod liver oil (CRM 349) Certified values Measured values
CB28
CB52
CB101
CB118
CB153
CB138
CB180
100_+10 112± 26
79 _+9 97 _+6
134+ 11 160_+5
97 ± 11 111 ± 3
288_+18 316± 6
* 294 _+4
313 _+24 351 i 12
68 +_7 64 _+2
149_+20 160i 8
370 _+17 357_+19
456 _+31 457 _+18
938_+40 991 _+51
765 ± 45 733 _+59
282 i 22 348 _+38
No certifiedvalue is provided for CB138 in CRM392.
only in sediments from two shallow coastal stations (Fig. 1, stations 6 and 8). In all the other samples all other CBs were below the detection limit. It has to be emphasized that the criterion to consider a compound detectable or quantifiable was based on the concentration expressed on basis of dry weight (dw), as were the LODs and LOQs (cf. Table 2). All the 20 CB congeners mentioned above were below the detection limit. Of the pesticides, p , p ' - D D E could be quantified only in sediments from the shallow estuarine zone of the Sabaki, whereas the concentration of a-HCH increased across the continental shelf towards the deep sea (Table 2). Also along the transects across the continental shelf off Formosa Bay (Tana river mouth) and Kiwayu Bay, cz-HCH could be quantified up to levels of 6 0 - 9 0 n g g ~ OC [ ~ 0 . 4 n g g - 1 (dw), v 0 . 2 5 n g g 1 wet weight (ww)], mainly in deeper stations along the Sabaki transect. In sediments from 500 to 2000 m deep along the Gazi and Kiwayu transects, as well as in sediments from 20 to 40 m deep along the Sabaki transect, y-HCH could be quantified. Sediments from the shallowest sampling site (18 m), and closest to the Sabaki river mouth showed relatively high concentrations of dieldrin ( 3 7 n g g 1 O C v 0 . 2 1 n g g - 1 dw ~ 0 . 0 9 n g g -1 ww), p , p ' - D D D (90ngg 1 OC ~ 0 . 4 6 n g g -1 dw ~ 0 . 1 9 n g g ~ ww) and p , p ' - D D E (510ngg -10C ~ 2 . 6 n g g -1 dw ~ l . 0 8 n g g 1 ww). None of the other compounds of the DDT-family nor endrin was identified in any of the other samples. In comparison, surface sediments from a depth of 50 to 250 m of the north-eastern part of the Indian Ocean (Arabian Sea) along the west coast of India, showed concentration which were one to three orders of magnitude higher (Sarkar and Sen Gupta, 1991; Sarkar and Sen Gupta, 1993; Shailaja and Sarkar, 1993). Here the concentrations of ~- and 7-HCH, dieldrin and ~DDT (DDT plus its metabolites) were 0 . 4 - 1 7 . 9 n g g 1 ww, 0 . 8 - 6 . 3 n g g 1 ww, 0 . 1 - 5 . 4 n g g -1 ww, and 7 - 1 8 0 n g g -~ ww, respectively. The highest levels measured in the sediments from the Kenyan coast were 0.25 for <,-HCH, 0.11 for 7-HCH, 0.09 for dieldrin, 0.19 f o r p , p ' - D D D , and 1.08 f o r p , p ' - D D E , all concentrations being quoted in ng g - i and (re)calculated on the basis of wet weight (cf. Table 2). In
estuarine and coastal sediments of the Fiji islands, no PCBs and generally very low concentrations of pesticides ( < 0 . 1 n g g -1 dry weight) were determined (Harrison et al., 1996; Morrison et al., 1996), whereas relatively high concentrations (e.g. up to 17 ng g - i dw for p,p'-DDE, 8 n g g -1 dw for dieldrin and 7 0 n g g 1 dw for PCBs) were observed only in sediments of sampling locations near the two major ports (Harrison et al., 1996; Morrison et al., 1996). Thus, the concentrations of the CB congeners and pesticides detected in the surface sediments of the Kenyan coastal zone and continental slope belong to the lowest levels measured. If detectable at all, concentrations are all in the low ng-range ( < 1.3 ng g - 1 dw), indicative of a 'non-polluted' area (UNEP/IAEA/IOC/FAO, 1992). In surficial sediments from the inshore estuarine areas of Mombasa, the concentrations of major organochlorine pesticides generally were below 0.1 mg kg 1 (100 ng g 1) dry weight (Williams et al., 1997). In the present study, the highest value found for any specific pesticide (viz. p,p'-DDE) was 2.6 ng g ~, on a dry wieght basis, which is 40 times lower than the 100 ng g-1 dw considered by Williams et al. (1997), as a baseline for the sediments of Mombasa's inshore estuaries, against which the impact of future urban and industrial expansion can be evaluated. With respect to environmental quality, however, the values for PCBs and pesticides in the surface sediments of the coastal area of Malindi, influenced by the Sabaki river run-off, should be considered as baseline concentrations. For macrobenthic organisms, Table 3 summarizes the number of individuals for each species, the percentage of lipid extracted, the amount of extracted lipid and data on the concentrations of the seven CB congeners and p,p'-DDE. A specific PCB pattern (technical mixture Clophen A50) was observed in the chromatograms, and most of the seven CB congeners were quantified, with a few exceptions only. Most of the 20 additional CB congeners which were considered, were below the detection limits and only a few could be identified. Figure 2 shows representative chromatograms for the standard solution of CB congeners, procedural blanks and CB congener fraction of total body homogenates of the species collected. The 495
4~
TABLE 2
28
0.08 0.20
35.2 (0.31)
n.d
n.d n.d n.d 0.04 0.10
n.d
n.d
+
n.d n.d n.d n.d
n.d 11.4 (0.16) n.d 12.4 (0.45) n.d n.d n.d n.d n.d
24.6 (0.34) 14.9 (0.22)
43.4(~23)
n.d n.d +
+
4~2 ~ 3 ~
n.d +
4Z5 (~66) 62.2 ~ 2 ~
n.d + n.d
n.d n.d n.d n.d
52
n.d n.d n.d n.d n.d 0.05 0.11
n.d n.d n.d n.d
n.d 11,2 (0.15) n.d 18.8 (0.40) n.d n.d n.d n.d n.d
n.d n.d n.d n.d
101
n.d n.d n.d n.d n.d 0.08 0.20
n.d n.d n.d n.d
n.d + n.d n.d n.d n.d n.d n.d n.d
n.d n.d n.d n.d
118
n.d n.d n.d n.d n.d 0.04 0.10
n.d n.d n.d n.d
n.d 12.9 (0.18) n.d 25.2 (0.35) n.d n.d n.d n.d n.d
n.d n.d n.d n.d
153
Chlorinated biphenyl congener no. (CB-):
n.d n.d n.d n.d n.d 0.08 0.20
n.d n.d n.d n.d
n.d + n.d n.d n.d n.d n.d n.d n.d
n.d n.d n.d n.d
138
n.d n.d n.d n.d n.d 0.04 0.10
n.d n.d n.d n.d
n.d n.d n.d n.d n.d n.d n.d n.d n.d
n.d n.d n.d n.d
180
n.d 8.7 (0.12) 11.5 (0.17) 7.4 (0.11) n.d 0.04 0.11
n.d n.d + n.d
+ + 23.9(0.39) 14.4 (0.20) 86.7(0.39) 59.4(0.38) + n.d 15.8(0.15)
n.d n.d n.d n.d
a-HCH
n.d n.d 18.2 (0.27) n.d 42.0 (0.37) 0.05 0.14
n.d n.d n.d n.d
n.d 10.0 (0.14) n.d 33.8 (0.47) n.d + n.d n.d n.d
n.d n.d 53.2 (0.25) n.d
7-HCH
n.d n.d n.d n.d n.d 0.07 0.19
n.d n.d n.d n.d
37.3 (0.21) n.d n.d n.d n.d n.d n.d n.d n.d
n.d n.d n.d n.d
Dieldrin
n.d n.d n.d n.d n.d 0.08 0.20
n.d n.d n.d n.d
90.2(0.46) n.d n.d n.d n.d n.d n.d n.d n.d
n.d n.d n.d n.d
p~p'-DDD
Pesticides
n.d n.d n.d n.d n.d 0.07 0.19
n.d n.d n.d n.d
n.d n.d n.d n.d
509.8 (2.60) 32.1 (0.25) 120.6(1.87) 125.2 (1.74)
n.d n.d n.d n.d
p,p'-DDE
0.51 1.38 1.48 1.08 0.88 -
0.11 0.57 0.97 0.53
0.51 1.40 1.55 1.39 0.45 0.64 0.65 0.65 0.95
0.46 1.05 0.47 0.65
%OC
n.a. is not analyzed; n.d. is not detectable; + is identified, but below quantification limit. Eudrin, o,p'-DDT a n d p , p ' - D D T could not be detected in any of the samples. In the sample GC runs for CB determination, the % recovery of internal standard CBl12 was 74.3 ± 6.8; % recovery in C R M and blank runs is 86.6 _+5.1. In the sample GC runs for pesticide determination, the % recovery of internal standard CB155 is 84.5 _+ 11.6; % recovery in C R M and blank runs is 84.5 _+11.6; % recovery in C R M and blank runs was 80.3 +__8.6. LOD and LOQ were considered on the basis of a 1 ~tl injection from a 1 ml extract. Note: Although identified and quantified as such, the values of CB28 indicated in italic do not refer to the actual concentration of CB28, but rather represent either compounds released by column bleeding or unknown components in the sample (e.g. phthalates).
24 54 505 950 2023
19 101 992 2145
Tana transect 14 15 16 17
Kiwayu Transect 18 19 20 21 22 LOD LOQ
18 20 31 40 64 218 518 1115 2063
Sabaki t r i s e c t 5 6 7 8 9 10 11 12 13
Coastal zone and continental slope of Kenya (Fig. 1) Gazi transect 1 62 54.3 (0.25) 2 511 110.5 (1.16) 3 1004 200.0 (0.94) 4 2053 78.5 (0.51)
Sampling location #
Depth (m)
The concentration (in ng/g organic carbon, and in ng g - 1 dry weight between brackets) of seven selected polychlorinated biphenyl congeners and five chlorinated pesticides in bulk surface sediments (0.5 cm top layer) from the coastal zone and the continental slope of Kenya. The fractions of total organic carbon is given ( % O C )
==
5"
"--.I
Animal group/species
N
14.5 37.7 28.5 14.4 12.0 31.2 38.8 82.5 62.6 987.1 32.0 35.1 3.5 120.1 23.9 31.8 63.4 17.0 18.1
74.8 18.5 30.9 38.1 28.8 36.6 85.5 117.3 193.8 41.2 26.4 29.8 53.2 32.7 32.2 21.9 38.2 37.9 LOD LOD
2.07 45.5 0.22 1.12 0.31 2.88 1.18 0.97 1.08 3.45 0.92
1.21 5.93 1.18 0.75 0.49 1.18 1.72 4.20 61.6 1.37 1.37 1.20 0.90 1.36 0.62 1.21 0.62 1.63
A m o u n t of extracted lipid (rag):
0.46 1.28 1.04 0.95 0.94 1.34 1.45 2.09
% lipid extract
+ + + + + 5.3 + 3.2 1.18 3.04
3.0
9.5 11.1
n.d n.d + + + + 2.4
7.9
9.3 3.1
2.3 2.2 0.9 1.7 1.0 4.8 n.d 10.7 0.14 0.32
n.d 2.4 1.5 0.5 n.d 1.7 1.0 0.9 0.4 2.6
7.4 + 15.0 1.0 1.8 1.1 1.5 n.d 11.8
12.6 + 22.8 n.d 4.5 +
3.7 0.7
5.1 1.8 1.5 10.0 39.5 1.7 1.I 1.5
52
6.2 9.7
+ + + 9.7 7.5 3.2 + Z2
28
4.5 4.0 3.0 3.5 + 5.3 1.7 25.3 0.52 2.60
+ 5.5 4.0 + 5.1 4.3 + + n.d 4.1
4.1 + 10.6 + 4.2 + 1.3 2.5 30.7
5.2 0.8
7.8 2.8 + 14.9 49.2 10.0 4.5 +
101
1.1 n.d 1.9 2.6 n.d 2.6 n.d 35.3 0.19 0.49
n.d n.d 4.3 n.d 3.5 4.9 + 0.6 0.5 4.0
1.7 n.d 4.1 n.d n.d n.d 1.6 n.d 27.9
4.5 0.5
n.d 0.8 n.d. 28.1 54.5 2.3 n.d 0.9
118
5.7 3.5 1.4 3.4 2.8 9.7 2.0 52.1 0.44 1.10
2.l 6.2 5.7 2.9 6.9 15.9 7.9 1.8 2.6 7.2
2.5 1.2 39.1 2.1 7.6 2.8 2.0 4.1 24.2
4.8 1.9
6.1 4.1 3.8 29.0 65.6 6.7 4.8 2.6
153
4.9 2.6 n.d 5.9 3.3 5.5 1.8 28.5 0.40 1.06
1.1 5.3 5.8 1.5 7.2 15.7 1.3 1.3 2.1 6.3
2.0 n.d 44.6 1.6 3.9 2.4 1.8 n.d 36.4
5.0 1.0
3.3 3.4 3.9 23.3 64.4 5.1 2.1 1.7
138
Chlorinated biphenyl cogener no. (CB-):
0.6 n.d n.d n.d n.d n.d n.d 3.2 0.15 0.39
1.8 n.d 3.1 n.d 4.9 11.8 1.1 + 1.7 n.d
1.3 0.8 28.6 n.d n.d n.d 0.8 n.d 5.8
2.4 1.4
3.6 n.d 5.0 n.d 7.5 n.d 1.3 2.0
180
3.9 5.0 2.2 3.2 2.3 4.8 1.9 25.6 0.13 0.31
7.7 21.2 6.1 15.1 14.0 9.8 17.3 0.8 n.d 8.6
2.3 4.8 31.3 4.6 5.0 1.9 1.9 2.4 23.1
2.7 29.1
34.5 15.7 9.0 18.5 47.8 2.9 3.0 0.5
p,p'-DDE
In the GC runs for CB determination in samples, the % recovery of internal standard C B l 1 2 is 74.3 _+6.8; % recovery in C R M and blank runs is 93.7 _+6.0. L O D and L O Q are considered on the basis of a 1 ~tl injection from a 1 ml extract. Note: Although identified and quantified as such, the values of CB28 indicated in italic do not refer to the actual concentration of CB28, but rather reflect either c o m p o u n d s released by column bleeding or unknown components in the sample (e.g. phthalates).
South-east m o n s o o n period - - June/July Formosa Bay - - River Sabaki m o u t h 8-9/50 m Echinodermata, Ophiuridae (brittle-star) 12 03°09'S Crustacea, Penaeus sp. (tiger-prawn) 6 40°14'E Crustacea, Metapenaeus sp. (prawn) 5 Mollusca, Bivalvia, Venus sp. 40 Mollusca, Bivalvia, Anadara sp. 6 10/220 m Crustacea, Metapenaeus sp. (prawn) 10 03°10'S Crustacea, Penaeus sp. (red-prawn) 7 40°18'E Pisces, Bothidae,flatfish 5 Formosa Bay - - River Tana m o u t h 14/20 m Echinodermata, Ophiuridae (brittle-star) 6 02°42'S Pisces, Tetraodonthidae (pufferfish, liver) 7 40°31'E Kiwayu Bay 18/20 m Echinodermata, Ophiuridae (brittle-star) 15 02°04'S Crustacea, Metapenaeus sp. (tiger-prawn) 10 41°18'E Mollusca, Bivalvia, Venus sp. 4 19/50 m Crustacea, Penaeus sp. (red-prawn) 10 02°01'S Crustacea, Penaeus sp. (tiger-prawn) 10 41°20'E Crustacea, Metapenaeus sp. (prawn) 18 Crustacea, Pagurus sp. (hermit-crab) 10 Mollusca, Bivalvia, Mactra sp. 7 Mollusca, Gastropoda, Nassarius sp. 25 North-east m o n s o o n period - - N o v e m b e r / D e c e m b e r Formosa Bay - - River Sabaki m o u t h 8-9/50 m Echinodermata, Ophiuridae (brittle-star) 17 03°09'S Crustacea, Penaeus sp. (tiger-prawn) 2 40°14'E Crustacea, Metapenaeus sp. (prawn) 10 Mollusca, Bivalvia, Anadara sp. 17 Mollusca, Bivalvia, Pema viridis 9 10/220 m Crustacea, Penaeus sp. (red-prawn) 6 03°10'S Crustacea, Pagurus sp. (hermit-crab) 9 40°18'E Crustacea, Pagurus sp. ( + eggs) 7 Pagurus eggs 7 Mollusca, Cephalopoda, Sepia sp. 3 Kiwayu Bay 18/20 m Crustacea, Penaeus sp. (tiger-prawn) 12 02°04'S Crustacea, Penaeus sp. (tiger-prawn) 7 41°18'E Crustacea, Metapenaeus sp. (prawn) 7 Crustacea, Metapenaeus sp. (prawn) 5 Crustacea, Portunidae (swimming=crab) 6 Crustacea, Majidae (spider-crab) 15 Mollusca, Bivalvia, Venus sp. 10 Mollusca, Cephalopoda (Sepia sp.) 3 n.d. is not detectable; + is identified but below quantification limit.
Station # / Depth (m)/ Geographic position:
TABLE 3 Concentrations . of seven . selected . . polychlorinated . . biphenyl congeners and ,I.p,p'-DDE in macrobenthic invertebrates and two fish species_ from the coastal zone and the continental slope1_of Kenya_ .(Fig . ),1" the n u m b e r of individuals (N) m a sample of various species, the percentage lipid extracted (in mg), the absolute a m o u n t of extracted lipid (in rag) and the concentration (in ng g - extracted lipid)
Go
7=
t~
g
r~
<
Marine Pollution Bulletin 112 ISTD
i
10'
1 1,9 1 t381 i
99
I
187
52 28
44 74 49 i
1111281128 i
IR
t~ol[l~ ;/
~IUu,~.~r.,x141
~1( 118132 136
~
177
158
1,9/1~9
StandardPoychorobpheny,s./ Procedure
w
153
l
1
__~4. 9
t98 ,9,
~09 DOE
blank
5< ~ ....... \ ~'~
I 153 138
180
ill
,0,
is0
H ,~
ls3
Fig. 2 Representative capillary GC-ECD chromatograms of the polychlorinated biphenyl standard, the procedural blank and six animal species collected from the estuarine and nearby coastal zone of Formosa Bay at the River Sabaki mouth (near Malindi, Kenya): (1) Echinodermata, Ophiuridae-brittle-star; (2) Crustacea, Natantia, Penaeidae, Metapenaeus sp. - - prawn; (3) Crustacea, Natantia, Penaeidae, Penaeus sp. - - tiger prawn; (4) Crustacea, Reptantia, Paguridae, Pagurus sp, - hermit crab; (5) Mollusca, Bivalvia, A n a d a r a sp. - - cockle; and (6) Mollusca, Bivalvia, Perna viridis - - green mussel. The individual l l 2 / I S T D = C B congener 112 applied as internal standard.
498
Volume 36/Number 6/June 1998
chromatograms clearly demonstrate the presence of CB153 and p,p'-DDE. By far the highest levels of CBs were found in bivalve molluscs from the Sabaki river mouth [30 and 65 ng g-1 lipid of CB153, which is 0.29 and 0.62 ng g - 1, calculated on the basis of wet weight (ww), respectively] and Kiwayu Bay (39 ng g 1 lipid weight of CB153~0.12 ng g-1 ww), and in gastropod molluscs from Kiwayu Bay (24 ng g-1 lipid weight of CB153~0.23 ng g-1 ww). Of the cyclic pesticides, only p,p'-DDE was analyzed, and was present in all samples, in enhanced levels varying between 15 and 48 ng g lipid weight, in bivalve and gastropod molluscs. In several fish species from the Athi river estuary at Malindi (Fig. 1), which is the same area indicated here as the Sabaki river mouth, low levels of pesticides such as lindane, aldrin and DDT-family members were established by Mugachia et aI. (1992). For example, their studies revealed whole body residues ofp,p'-DDE from an average value of 10 ng g 1 wet weight (ww) in sole, to 125 ng g-1 ww (range 25-300 ng g-~) in catfish or 150ngg -1 ww (range 30-425ngg -1) in bream. p,p'-DDE constituted 92, 86 and 72% of the YDDT concentration in sole, catfish and bream, respectively (Mugachia et al., 1992). In comparison, the DDE level measured in flatfish (Bothidae) in the present work was three orders of magnitude lower viz. 0.5ngg -1 extracted lipid ( ~ 0 . 0 1 n g g -1 ww), whereas in liver from pufferfish (Tetraodonthidae) the DDE concentration was 29 ng g-1 lipid ( ~ 13.5 ng g-1 ww). However, apart from these few fish tissue samples, data reported here refer exclusively to PCBs and p,p'-DDE in macrobenthic invertebrates since, in ecological terms, they are more representative for a specific habitat or area than are (migratory) fish. The concentrations of CB congeners and p,p'-DDE in the invertebrates were substantially enhanced compared to the same groups of species sampled in the coastal zone and continental slope of the Banc d'Arguin (Mauritania), where the CB congeners 153 and 138 could not be quantified, but identified only (Everaarts et al., 1993). The levels found in benthic invertebrates from Kenyan coastal waters were two to three orders of magnitude lower than in comparable macrobenthic fauna from the shallow Java Sea and Strait Madura, the Bali basin (Indonesia) and the Java Trench (Indian Ocean) depending on the species considered (see Boon et al., 1989). For example, in penaeid prawns from the nearby coastal and estuarine zones particularly, the p,p'-DDE ranged from 100 to 4500 ng g-1 lipid weight, whereas CBs 118 and 180 ranged from 10 to 180ngg -~ and 10 to 360ngg -~ lipid weight, respectively (Boon et al., 1989). Also in comparison with other tropical estuarine systems such as along the coast of the Malay peninsula (Everaarts et al., 1991), the concentrations of CB congeners and p,p'-DDE in penaeid prawns and bivalve molluscs from the coastal zone of Kenya were 3 to 20 times lower. Harrison et al. (1996) reported p,p'-DDE levels of 0.2-1.0 ng g-1 dry weight in shell-
fish (Gafrarium tumidum) from a Pacific lagoon (Tonga). Although it was not possible to recalculate and express these levels on the basis of wet weight or extracted lipid, it can be estimated that these low levels are similar to the concentrations found in prawns and bivalves from Kenya. In a riverine mussel (Batissa violacea) from Fiji (Pacific), collected near a rice irrigation project, p,p'-DDE concentrations of 11.5 and 16.1 ngg -1 dry weight were found (Morrison et al., 1996), which are 10-fold higher than in the mussel Perna viridis from the Sabaki river mouth. In summary, the Kenyan marine environment studied here exhibited a low degree of contamination. Only in the shallow estuarine areas near the outflow of the Sabaki River, CB congeners, dieldrin, p,p'-DDD and p,p'-DDE could be quantified in enhanced levels in surface sediments. Concentrations of ~-HCH tended to increase gradually across the continental slope, while •-HCH could be detected in only a few deeper locations. The pesticides f3-HCH, endrin, p,p'-DDT and o,p'-DDT could not be identified in any of the sediment samples. In benthic invertebrates CB congeners and p,p'-DDE could be quantified, although generally, concentrations were only a factor of 2-4 above the limit of quantification. Thus, although the coastal area of Kenya is measurably impacted by discharges of rivers and by the activities of Mombasa harbor and industry, the degree of contamination is low. One of the reasons for this might be the extremely strong currents along a narrow coastal zone, both during the southeast and northeast monsoon (Anon, 1991), causing a very short residence time of particles (including adsorbed or lipid associated organic contaminants) in the coastal waters. Atmospheric transport might be responsible for enhanced levels of HCHs in offshore areas. The data reflected the interspecific differences in uptake and accumulation of CB congeners and p,p'-DDE. In bivalve and gastropod molluscs relatively high levels of CBs and p,p'-DDE were established, but similar values were also found in edible penaeid prawns. However, none of the samples had residue levels of PCBs or pesticides above the extraneous residue limits (ERL) and acceptable daily intake (ADI) set by the FAO/WHO Codex Alimentarius Commission (1986). With respect to human health, the concentrations of all of the PCBs and pesticides measured, both in bivalve moluscs and crustaceans, were far below the maximum admissible concentration (MAC). For example, in fishery products for human consumption, the MAC value for ~]DDT, ~- and ~-HCH, dieldrin and CB153 is 500, 50, 50 and 100 ng g-1 ww, respectively (Van der Valk, 1989). These values agree with the values for acceptable (daily) intake, which are based on WHO standards and take into account the general consumption pattern. This research has been carried out as a part of the Netherlands Indian Ocean Program 1990-1995, Project A, Monsoons and Coastal
499
Marine Pollution Bulletin Ecosystems in Kenya. The programme was organized and funded by the Netherlands Marine Research Foundation (SOZ) of the Netherlands Organization for Scientific Research (NOW). Special thanks are due to Captain J. de Jong and the late Captain kJ. Blok and their crew of the R.V. Tyro, and the technicians on board during the surveys. Thanks are also due to R. Kloosterhuis for performing the analyses of total organic carbon, and M. Lavaleye for the determination of the benthic species. This is Publication number 3101 of the Netherlands Institute of Sea Research. Anon (1984) PCB regulation. Dutch Staatscourant, The Hague, The Netherlands. Anon (1988) Verordnung fiber H6chstmengen an Schadstoffen in Lebensmitteln Bundesgesetzblatt, Teil 1. Bonn, Germany, pp. 422-424. Anon (1991) Netherlands Indian Ocean Program 1990/1995. Scientific Program Plan. Netherlands Marine Research Foundation, The Hague, pp. 1-118. Ballschmiter, K. and Zell, M. (1980) Analysis of polychlorinated biphenyls (PCB) by glass capillary gas chromatography. Composition of technical arochlor and clophen-PCB mixtures. Fresenius' Z. Anal. Chem., 302, 20-31. Bligh, E. G. and Dyer, W. J. (1959) A rapid method of total lipid extraction and purification. Can. J. Biochem. Physiol., 37, 911-917. Boon, J. P., Everaarts, J. M., Kastoro, W., Razak, W., Sumanta, I., Sumarno, Nelissen, P. H., .Stefels, J. and Hillebrand, M. Th. J. (1989) Cyclic organochlorines in epibenthic organisms from coastal waters around East Java. Neth. J. Sea Res., 23, 427-439. De Boer, J. and Dao, Q. T. (1991) Analysis of seven chlorobiphenyl congeners by multidimensional gas chromatography. J. High Resolut. Chromatogr., 14, 593-596. De Boer, J. and Wells, D. E. (1996) The 1994 QUASIMEME laboratory-performance studies: .chlorobiphenyls and organochlorine pesticides in fish and sediment. Marine Pollut. Bull., 32, 654-666. Dninker, J. C. and Hillebrand, M. Th. J. (1978) Minimizing blank values in chlorinated hydrocarbon analysis. J. Chromat., 150, 195-199. Duinker, J. C. and Hillebrand, M. Th. J. (1983) Characterization of PCB components in clophen formulations by capillary GC-MS and GC-ECD techniques. Environ. Sci. TechnoL, 17, 449-456. Everaarts, J. M. and Nieuwenhuize, J. (1995) Heavy metals in surface sediment and epibenthic macroinvertebrates from the coastal zone and continental slope of Kenya. Marine Pollut. Bull., 31, 281-289. Everaarts, J. M., Bano, N., Swennen, C. and Hillebrand, M. Th. J. (1991) Cyclic chlorinated hydrocarbons in benthic invertebrates from three coastal areas in Thailand and Malaysia. J. Sci. Soc. Thailand, 17, 31-49. Everaarts, J. M., Heesters, R., Fischer, C. V. and Hillebrand, M. T. J. (1993) Baseline levels of cyclic pesticides and PCBs in benthic invertebrates from the continental slope of the Banc d'Arguin (Mauritania). Marine Pollut. Bull., 26, 515-521.
500
FAO/WHO Codex Alimentarius Commission, 1986. Codex maximum limits for pesticide residues, 2nd edn. Grobler, D. F., Badenhorst, J. E. and Kempster, P. L. (1996) PCBs, chlorinated hydrocarbon pesticides and chlorophenols in the Isipingo estuary, Natal, Republic of South Africa. Marine Pollut. Bull., 32, 572-575. Harrison, N., Gangaiya, P. and Morrison, R. J. (1996) Organochlorines in the coastal marine environment of Vanuata and Tonga. Marine Pollut. Bull., 32, 575-579. Holden, A. V. and Marsden, K. (1969) Single-stage clean-up of animal tissue extracts for organochlorine residue analysis. J. Chromat., 44, 481-492. Morrison, R. J., Harrison, N. and Gangaiya, P. (1996) Organochlorine contaminants in the estuarine and coastal marine environments of the Fiji islands. Environ. Pollut., 93, 159-167. Mugachia, J. C., Kanja, L. and Maitho, T. E. (1992) Organochlorine pesticide residues in estuarine fish from the Athi river. Kenya BulL Env. Contam. Toxicol., 49, 199-206. Preston, M. R. (1988) In: Riley, J. P. (Ed.), Marine Pollution. Chemical Oceanography, Vol. 9. Academic Press, London, pp. 54-196. Sarkar, A. and Sen Gupta, R. (1991) Pesticide residues in sediments from the west coast of India. Marine Pollut. Bull., 22, 42-45. Sarkar, A., Sen Gupta, R. (1993) On chlorinated hydrocarbons in the Indian Ocean. In: Desai, B.N. (Ed.), Oceanography of the Indian Ocean. A. A. Balkema, Rotterdam, The Netherlands, pp. 385-395. Schulz, D. E., Petrick, G. and Duinker, J. C. (1989) Complete characterization of polychlorinated biphenyl congeners in commercial arochlor and clophen mixtures by multidimensional gas chromatography-electron capture detection. Environ. Sci. Technol., 23, 852-859. Shailaja, M. S., Sarkar, A. (1993) Organochlorine pesticide residues in the northern Indian Ocean. In: Desai, B. N. (Ed.), Oceanography of the Indian Ocean. A.A. Balkema, Rotterdam, The Netherlands, pp. 379-383. UNEP/IAEA/IOC/FAO (1992) Organohalogen compounds in the marine environment: a review. MAP Technical Reports Series 70, United Nations Environmental Programme, Athens. Van der Valk, F. (1989) Overview of standards for contaminants in fishery products. Report of the Working Group on Environmental Assessments and Monitoring Strategies, Brest, France, 24-28 April 1989. International Council for the Exploration of the Seas, Copenhagen, pp. 43-46. Wells, D. E., De Boer, J., Tuinstra, L. G. M. T., Reuterg~rdh, L. and Griepink, B. (1998) Improvements in the analysis of chlorobiphenyls prior to the certification of seven CBs in two fish oils. Fresenius' Z. AnaL Chem., 332, 591-597. Williams, T. M., Rees, J. G., Ferguson, A., Herd, R. A., Kairu, K. K. and Yobe, A. C. (1997) Metals, petroleum hydrocarbons and organocblorines in inshore sediments and waters of Mombasa, Kenya. Marine Pollut. Bull., 0, 0 (in press).
mammals deal with high cadmium burdens may have significance for human medical treatment of cadmiuminduced renal degradation. Andr6, J.M., Ribeyre, F. and Boudou, A. (1990) Mercury contamination levels and distribution in tissues and organs of delphinids (Stenella attenuata) from the eastern tropical Pacific, in relation to biological and ecological factors. Marine Environmental Research, 30, 43-72. Dietz, R., Riget, F. and Johansen, P. (1996) Lead, cadmium, mercury and selenium in Greenland marine animals. The Science of the Total Environment, 186, 67-93. Dietz, R., Johansen, P., Riget, F. and Asmund, G. (1997) Heavy metals in the Greenland Marine Environment, National Assessment, ln: AMAP Greenland 1994-96, Arctic Monitoring and Assessment Programme (AMAP). Danish Environmental Protection Agency, Environmental Project, 356, 119-245. Dietz, R., Pacyna, J. and Thomas, D. J. (in press). Heavy metals. AMAP International Assessment, Arctic Monitoring and Assessment Programme, Oslo, Norway. Dragert, J., Corey, S. and Ronald, K. (1975) Anatomical aspects of the kidney of the harp seal Pagophilus groenlandicus (Erxleben, 1777). Rapport Process verbeaux R~union International Exploration de la Mer, 169, 133-140.
Marine PollutionBulletin, Vol. 36, No. 6, pp. 492-500, 1998 © 1998 Published by Elsevier Science Ltd. All rights reserved. Printed in Great Britain 0025-326X/98 $19.00+0.00
PII: 0025-326X(98)00029-0
Polychlorinated Biphenyls and Cyclic Pesticides in Sediments and Macro-invertebrates from the Coastal Zone and Continental Slope of Kenya J. M. EVERAARTS, E. M. VAN WEERLEE, C. V. FISCHERM and TH. J. HILLEBRAND Department of Marine Biogeochemistry and Toxicology, Netherlands Institute for Sea Research, PO Box 59, I 790 AB Den Burg, Texel, The Netherlands Over 70% of the Earth's surface consists of oceans, coastal seas and estuarine zones. The importance of marine ecosystems is also illustrated by the fact that the coastal area is inhabited by about 60% of the world's population. Thus, in particular, estuarine and coastal systems, showing considerable biological activity, are exposed to a high degree of contamination. The load of anthropogenic compounds induces impairment of various physiological functions of individual organisms and affects the ecological quality of ecosystems. Polychlorinated biphenyls (PCBs) and chlorinated pesticides (e.g. DDTs, dieldrin) show a global distribution. They are ubiquitous toxic contaminants, due to their bioaccumulative capacity and persistence and specific physico-chemical properties. Technical PCB mixtures or the individual CB congeners and pesticides accumulate in biota of all trophic levels and 492
Elinder, C.-G. and Jfirup, L. (1996) Cadmium exposure and health risks: recent findings. Ambio, 25, 370-373. Hansen, J.C., Toribara, T.Y. and Muhs, A.G. (1989) Trace metals in human and animal hair from the 15th century graves at Qilakitsoq compared with recent samples. Meddelelser om GrOnland, Man and Society, 12, 161-167. Law, R. J. (1996) Metals in marine mammals. In Environmental Contaminants in Wildlife. Interpreting Tissue Concentration, eds. W. N. Beyer, G. H. Heinz and A. W. Redmon-Norwood, pp. 357-376. SETAC Special Publication Series. CRC Press Inc., Lewis Publishers Inc., Boca Raton, FL. Loring, D.H. and Astound, G. (1996) Geochemical factors controlling accumulation of major and trace elements in Greenland coastal and fjord sediments. Environmental Geology, 28, 2-11. Nilsson, A. (1996) Arctic pollution issues: a state of the Arctic environment report. Arctic Monitoring and Assessment Programme, Oslo, Norway. Wagemann, R., Innins, S. and Richard, P. (1996) Overview and regional and temporal differences of heavy metals in Arctic and ringed seals in the Canadian Arctic. The Science of the Total Environment, 186, 41-66. WHO (1992) Cadmium. Environmental Health Criteria, Vol. 134. World Health Organization, Geneva.
residues are reported in environmental compartments from all geographical latitudes (Preston, 1988; Everaarts et al., 1993). However, from certain regions such as the South Pacific and the western Indian Ocean, contaminant levels in various environmental compartments were neither extensively investigated nor well reported. Only recently, data from these areas were published, indicating low levels of PCBs and DDTs in water and fish from an estuary on the east coast of South Africa (Grobler et al., 1996). Levels of PCBs and a wide variety of pesticides were determined just above their detection limit in sediments and shellfish from Vanuatu and Tonga (Harrison et al., 1996). Concentrations of a wide variety of organic compounds in the estuarine and coastal environment of the Fiji Islands were also found to be low (<10 ng g-1 dry weight), and it was suggested that organochlorine pesticides had undergone conversion reactions, particularly enhanced due to the tropical climatic conditions (Morrison et al., 1996). Research on marine pollution is a priority area within the research and monitoring programs of the Kenyan Marine Fisheries Institutes, and necessary for pollution management and decision making (Anon, 1991). Pollution studies in the marine environment of Kenya mainly focused on the estuarine and coastal zone in the vicinity of Mombasa (T. Williams et al., 1997). However, other coastal areas, such as the Sabaki and Tana river mouths are even more impacted by freshwater run-offs or riverine influences. To the author's knowledge, only one publication reports on residues of organochlorine pesticides in fish from the estuarine environment of Kenya (Mugachia et al., 1992), which were considered to be low. The present study contributes to knowledge on the status of the marine ecosystems along the coast of
Volume 36/Number 6/June 1998
locations and some of the hydrographic characteristics (salinity and temperature of bottom and surface water) have been published previously (Everaarts and Nieuwenhuize, 1995). Surface sediment samples were taken by means of sub-sampling the upper 5 mm layer of undisturbed sediment cores that were obtained with a Reineck box corer. From the sediments, approximately 20 g wet weight was wet extracted by vigorously mixing with a mixture of isopropanol, hexane and water, modified according to a rapid method of total lipid extraction and purification (Bligh and Dyer, 1959). The animal species, collected with a beam-trawl and a trawling time of 5-10 min, represented a number of
Kenya and its continental slope, in terms of the concentrations of anthropogenic lipid-associated cyclic halogenated hydrocarbons (PCBs, members of the DDT family, HCH-isomers and dieldrin) in sediment and selected benthic macroinvertebrates. Samples were obtained from the coastal zone and continental slope of Kenya (the Indian Ocean). Two surveys with the research vessel TYRO in 1992, from 18 June to 9 July (south-east monsoon), and from 19 November to 8 December (onset of the north-east monsoon) covered sampling locations in different areas of the coastal zone and along transects radiating into the Indian Ocean perpendicular to the Kenyan coast (Fig. 1). The geographic positions of the sampling 40 °
41°
I
,
42°
I
,
..
~;.
J"
I
.,ooO"
r .z °
20 < \ .t ~ o n o _ _
/
o=u" ~.~;.uBoy; ,.--(:-'" ,
.:.."
,. i
',
l"
.,...", , .o; For mos° Boy f
Y"
b
~
oo ,~
./
.u
./
.-/
I _ 3 °
SObok/
78/ Molindi
i.:"~910
/
•
12o
11
i3
,[oo " ~:--..,.,
2
_4 o
i l! /
o2
3o
I
4 0
p.t ~. -
IoO0
~zo.:. i.:,"
~g,
~'....."
", iI
o
o
4'oo
;lo
4'20
Fig. 1 Area of investigation in the estuarine and coastal zone and the continental slope of Kenya. Sampling sites are located along transects radiating into the Indian Ocean perpendicular to the Kenyan coast: Gazi transect (stations 1-4), Sabaki transect (stations 5-13), Tana transect (stations 14-17) and the Kiwayu transect (stations 18-22).
493
Marine Pollution Bulletin phyla (see below). About 3-5 g wet weight of whole body or specific tissue, measured to the nearest 0.01 g, was homogenized with as much anhydrous sodium sulphate (Na2SO4) necessary to obtain a dry-running mixture. Subsequently, the samples were Soxhlet extracted for 8h with 150ml of a 1:1 mixture of dichloromethane and pentane. The entire analytical procedure for chlorinated hydrocarbons, including sample extraction, clean-up, fractional separation of PCBs and most pesticides and pretreatment of the chemicals used, has been described earlier (Holden and Marsden, 1969; Duinker and Hillebrand, 1978, 1983; Everaarts et aI., 1993). Analyses of the samples were performed using a temperature-programmed gas chromatograph (Hewlett-Packard 5880a) equipped with a 60 m fused silica capillary column (0.15 mm diameter, 0.30 gm wall coating) with CP-SiI19 as stationary phase and a 63Ni-electron capture detector (ECD). Hydrogen was used as the carrier-gas at a pressure of 350 kPa and linear gas velocity of 30 cm min - 1. The temperature of the injector and detector was 230 and 340°C, respectively. Split-splitless injections of 1 ~tl aliquots of each sample dissolved in 2,2',4-trimethylpentane were made with an autosampler (HP 7673A). The temperature programme consisted of isothermal phases at 90°C (4.5 min.), 215°C (25 min.) and 270°C (20 min.), with intermediate temperature increase of 10 and 5°C min 1, respectively. For the identification and quantification of the biphenyl congeners, a synthetic mixture of 44 individual congeners was employed, and CBll2 as an internal standard. The congeners determined and reported here were the seven CB-congeners being selected in several countries as indicators, the quantitation of which may be used to determine whether PCB levels in food products, waste mineral oil and environmental samples comply with the maximum levels permitted by legislation (Anon, 1984, 1988; Wells et al., 1988; De Boer and Dao, 1991). These congeners, given in sequence of elution in the chromatogram, are CB28 (2,4,4'-tri-CB), CB52 (2,2',5,5'-tetra-CB), CB101 (2,2',4,5,5'-pentaCB), CBll8 (2,3',4,4',5-penta-CB), CB153 (2,2',4,4',5,5'-hexa-CB), CB138 (2,2',3,4,4',5'-hexa-CB) and CB180 (2,2',3,4,4',5,5'-hepta-CB). These represent different levels of overall chlorination of the molecule and also differ in the site of the chloro-atom substitution to the biphenyl skeleton. The numbering of the congeners is shown according to IUPAC rules, as suggested by Ballschmiter and Zell (1980). Apart from these, a number of other congeners were considered whose environmental occurrence is well established and which appeared as well separated peaks in the chromatogram from the CP-Sill9, such as the tri-CBs 18, 15, 26, 31, the tetra-CBs 49, 44, 74, the penta-CBs 99, 97, the hexa-CBs 136, 149, 141, 128, the hepta-CBs 187, 183, 177, 170, the octa-CBs 194, 195, and the deca-CB209 (Schulz et al., 1989). Additionally the 494
non-ortho chlorinated congeners CB77 and CB126, and
the mono-ortho chlorinated CB101 and CB105 were considered. The environmental concentrations of these congeners are generally low, but are considered to be the most toxic. The pesticides ~- and 7-hexachlorocyclohexane (HCHs), dieldrin, endrin and DDT-family members (p,p'-DDT, o,p'-DDT, p,p'-DDD, o,p'-DDD and p,p'-DDE), were identified and quantified on the basis of a synthetic mixture of these compounds, using CB155 as internal standard. The standards were injected every 10th injection for recalibration of the retention time and the response factor of each compound. The response factor of each peak in the standard mixture representing either a CB congener or pesticide, did not differ more than 10% between successive analyses of the standards. A peak in a chromatogram of a sample was only assigned to a compound in the standard mixture when its retention time did not differ more than 0.025 rain. from that compound in the standard. For a positive identification, the peak pattern in the chromatogram was also taken into account. A compound was considered non-detectable (limit of detection; LOD) when the peak height was less than the value of the average of the analyte blank signals, plus three times the standard deviation of the blank (SDb). Peak heights with a value of the average of the analyte blank signals, plus three to nine times SDb, or plus above nine times the SDb, were considered as being identifiable only or appropriate for quantification (limit of quantification; LOQ), respectively. To control procedural blank levels, each series of five samples was accompanied alternately by a blank run of pure Na2SO4 and a complete analytical procedure with sewage sludge or cod-liver oil, being Certified Reference Material of the CEC Bureau for Certified Reference materials CRM392 or CRM349, respectively. The certified and measured values for the selected CB congeners 28, 52, 101, 118, 153, 138 and 180 are summarized in Table 1. All analytical steps and procedures were performed according to formalized Standard Operating Procedures and were undertaken in the framework of the intercalibration exercises of the EC program QUASIMEME, Quality Assurance of Information for Marine Environmental Monitoring in Europe. The analytical results achieved by the organic-analytical laboratory of the Netherlands Institute of Sea Research (serving as reference laboratory) were excellent (cf. De Boer and Wells, 1996). The concentrations (expressed on the basis of organic carbon, OC) of seven selected CB congeners and cyclic organochlorine pesticides in surface sediment and the content of total particulate organic carbon are presented in Table 2. In Kenyan coastal and offshore areas, CB congeners could be quantified (chromatograms also showing the specific PCB pattern)
Volume 36/Number 6/June 1998 TABLE 1
Certified and measured values of chlorobiphenylcongeners 28, 52, 101, 118, 153 and 180 in sewage sludge and cod-liver oil, CRM 392 (three analyses) and CRM 349 (five analyses), respectively, of the European Bureau for Certified Reference materials. Concentrations __+ standard deviation are expressedin ng g ~dry weight for sewage sludge and in ng g 1 extracted lipid for cod-liveroil
Sewage sludge (CRM392) Certified value Measured value Cod liver oil (CRM 349) Certified values Measured values
CB28
CB52
CB101
CB118
CB153
CB138
CB180
100_+10 112± 26
79 _+9 97 _+6
134+ 11 160_+5
97 ± 11 111 ± 3
288_+18 316± 6
* 294 _+4
313 _+24 351 i 12
68 +_7 64 _+2
149_+20 160i 8
370 _+17 357_+19
456 _+31 457 _+18
938_+40 991 _+51
765 ± 45 733 _+59
282 i 22 348 _+38
No certifiedvalue is provided for CB138 in CRM392.
only in sediments from two shallow coastal stations (Fig. 1, stations 6 and 8). In all the other samples all other CBs were below the detection limit. It has to be emphasized that the criterion to consider a compound detectable or quantifiable was based on the concentration expressed on basis of dry weight (dw), as were the LODs and LOQs (cf. Table 2). All the 20 CB congeners mentioned above were below the detection limit. Of the pesticides, p , p ' - D D E could be quantified only in sediments from the shallow estuarine zone of the Sabaki, whereas the concentration of a-HCH increased across the continental shelf towards the deep sea (Table 2). Also along the transects across the continental shelf off Formosa Bay (Tana river mouth) and Kiwayu Bay, cz-HCH could be quantified up to levels of 6 0 - 9 0 n g g ~ OC [ ~ 0 . 4 n g g - 1 (dw), v 0 . 2 5 n g g 1 wet weight (ww)], mainly in deeper stations along the Sabaki transect. In sediments from 500 to 2000 m deep along the Gazi and Kiwayu transects, as well as in sediments from 20 to 40 m deep along the Sabaki transect, y-HCH could be quantified. Sediments from the shallowest sampling site (18 m), and closest to the Sabaki river mouth showed relatively high concentrations of dieldrin ( 3 7 n g g 1 O C v 0 . 2 1 n g g - 1 dw ~ 0 . 0 9 n g g -1 ww), p , p ' - D D D (90ngg 1 OC ~ 0 . 4 6 n g g -1 dw ~ 0 . 1 9 n g g ~ ww) and p , p ' - D D E (510ngg -10C ~ 2 . 6 n g g -1 dw ~ l . 0 8 n g g 1 ww). None of the other compounds of the DDT-family nor endrin was identified in any of the other samples. In comparison, surface sediments from a depth of 50 to 250 m of the north-eastern part of the Indian Ocean (Arabian Sea) along the west coast of India, showed concentration which were one to three orders of magnitude higher (Sarkar and Sen Gupta, 1991; Sarkar and Sen Gupta, 1993; Shailaja and Sarkar, 1993). Here the concentrations of ~- and 7-HCH, dieldrin and ~DDT (DDT plus its metabolites) were 0 . 4 - 1 7 . 9 n g g 1 ww, 0 . 8 - 6 . 3 n g g 1 ww, 0 . 1 - 5 . 4 n g g -1 ww, and 7 - 1 8 0 n g g -~ ww, respectively. The highest levels measured in the sediments from the Kenyan coast were 0.25 for <,-HCH, 0.11 for 7-HCH, 0.09 for dieldrin, 0.19 f o r p , p ' - D D D , and 1.08 f o r p , p ' - D D E , all concentrations being quoted in ng g - i and (re)calculated on the basis of wet weight (cf. Table 2). In
estuarine and coastal sediments of the Fiji islands, no PCBs and generally very low concentrations of pesticides ( < 0 . 1 n g g -1 dry weight) were determined (Harrison et al., 1996; Morrison et al., 1996), whereas relatively high concentrations (e.g. up to 17 ng g - i dw for p,p'-DDE, 8 n g g -1 dw for dieldrin and 7 0 n g g 1 dw for PCBs) were observed only in sediments of sampling locations near the two major ports (Harrison et al., 1996; Morrison et al., 1996). Thus, the concentrations of the CB congeners and pesticides detected in the surface sediments of the Kenyan coastal zone and continental slope belong to the lowest levels measured. If detectable at all, concentrations are all in the low ng-range ( < 1.3 ng g - 1 dw), indicative of a 'non-polluted' area (UNEP/IAEA/IOC/FAO, 1992). In surficial sediments from the inshore estuarine areas of Mombasa, the concentrations of major organochlorine pesticides generally were below 0.1 mg kg 1 (100 ng g 1) dry weight (Williams et al., 1997). In the present study, the highest value found for any specific pesticide (viz. p,p'-DDE) was 2.6 ng g ~, on a dry wieght basis, which is 40 times lower than the 100 ng g-1 dw considered by Williams et al. (1997), as a baseline for the sediments of Mombasa's inshore estuaries, against which the impact of future urban and industrial expansion can be evaluated. With respect to environmental quality, however, the values for PCBs and pesticides in the surface sediments of the coastal area of Malindi, influenced by the Sabaki river run-off, should be considered as baseline concentrations. For macrobenthic organisms, Table 3 summarizes the number of individuals for each species, the percentage of lipid extracted, the amount of extracted lipid and data on the concentrations of the seven CB congeners and p,p'-DDE. A specific PCB pattern (technical mixture Clophen A50) was observed in the chromatograms, and most of the seven CB congeners were quantified, with a few exceptions only. Most of the 20 additional CB congeners which were considered, were below the detection limits and only a few could be identified. Figure 2 shows representative chromatograms for the standard solution of CB congeners, procedural blanks and CB congener fraction of total body homogenates of the species collected. The 495
4~
TABLE 2
28
0.08 0.20
35.2 (0.31)
n.d
n.d n.d n.d 0.04 0.10
n.d
n.d
+
n.d n.d n.d n.d
n.d 11.4 (0.16) n.d 12.4 (0.45) n.d n.d n.d n.d n.d
24.6 (0.34) 14.9 (0.22)
43.4(~23)
n.d n.d +
+
4~2 ~ 3 ~
n.d +
4Z5 (~66) 62.2 ~ 2 ~
n.d + n.d
n.d n.d n.d n.d
52
n.d n.d n.d n.d n.d 0.05 0.11
n.d n.d n.d n.d
n.d 11,2 (0.15) n.d 18.8 (0.40) n.d n.d n.d n.d n.d
n.d n.d n.d n.d
101
n.d n.d n.d n.d n.d 0.08 0.20
n.d n.d n.d n.d
n.d + n.d n.d n.d n.d n.d n.d n.d
n.d n.d n.d n.d
118
n.d n.d n.d n.d n.d 0.04 0.10
n.d n.d n.d n.d
n.d 12.9 (0.18) n.d 25.2 (0.35) n.d n.d n.d n.d n.d
n.d n.d n.d n.d
153
Chlorinated biphenyl congener no. (CB-):
n.d n.d n.d n.d n.d 0.08 0.20
n.d n.d n.d n.d
n.d + n.d n.d n.d n.d n.d n.d n.d
n.d n.d n.d n.d
138
n.d n.d n.d n.d n.d 0.04 0.10
n.d n.d n.d n.d
n.d n.d n.d n.d n.d n.d n.d n.d n.d
n.d n.d n.d n.d
180
n.d 8.7 (0.12) 11.5 (0.17) 7.4 (0.11) n.d 0.04 0.11
n.d n.d + n.d
+ + 23.9(0.39) 14.4 (0.20) 86.7(0.39) 59.4(0.38) + n.d 15.8(0.15)
n.d n.d n.d n.d
a-HCH
n.d n.d 18.2 (0.27) n.d 42.0 (0.37) 0.05 0.14
n.d n.d n.d n.d
n.d 10.0 (0.14) n.d 33.8 (0.47) n.d + n.d n.d n.d
n.d n.d 53.2 (0.25) n.d
7-HCH
n.d n.d n.d n.d n.d 0.07 0.19
n.d n.d n.d n.d
37.3 (0.21) n.d n.d n.d n.d n.d n.d n.d n.d
n.d n.d n.d n.d
Dieldrin
n.d n.d n.d n.d n.d 0.08 0.20
n.d n.d n.d n.d
90.2(0.46) n.d n.d n.d n.d n.d n.d n.d n.d
n.d n.d n.d n.d
p~p'-DDD
Pesticides
n.d n.d n.d n.d n.d 0.07 0.19
n.d n.d n.d n.d
n.d n.d n.d n.d
509.8 (2.60) 32.1 (0.25) 120.6(1.87) 125.2 (1.74)
n.d n.d n.d n.d
p,p'-DDE
0.51 1.38 1.48 1.08 0.88 -
0.11 0.57 0.97 0.53
0.51 1.40 1.55 1.39 0.45 0.64 0.65 0.65 0.95
0.46 1.05 0.47 0.65
%OC
n.a. is not analyzed; n.d. is not detectable; + is identified, but below quantification limit. Eudrin, o,p'-DDT a n d p , p ' - D D T could not be detected in any of the samples. In the sample GC runs for CB determination, the % recovery of internal standard CBl12 was 74.3 ± 6.8; % recovery in C R M and blank runs is 86.6 _+5.1. In the sample GC runs for pesticide determination, the % recovery of internal standard CB155 is 84.5 _+ 11.6; % recovery in C R M and blank runs is 84.5 _+11.6; % recovery in C R M and blank runs was 80.3 +__8.6. LOD and LOQ were considered on the basis of a 1 ~tl injection from a 1 ml extract. Note: Although identified and quantified as such, the values of CB28 indicated in italic do not refer to the actual concentration of CB28, but rather represent either compounds released by column bleeding or unknown components in the sample (e.g. phthalates).
24 54 505 950 2023
19 101 992 2145
Tana transect 14 15 16 17
Kiwayu Transect 18 19 20 21 22 LOD LOQ
18 20 31 40 64 218 518 1115 2063
Sabaki t r i s e c t 5 6 7 8 9 10 11 12 13
Coastal zone and continental slope of Kenya (Fig. 1) Gazi transect 1 62 54.3 (0.25) 2 511 110.5 (1.16) 3 1004 200.0 (0.94) 4 2053 78.5 (0.51)
Sampling location #
Depth (m)
The concentration (in ng/g organic carbon, and in ng g - 1 dry weight between brackets) of seven selected polychlorinated biphenyl congeners and five chlorinated pesticides in bulk surface sediments (0.5 cm top layer) from the coastal zone and the continental slope of Kenya. The fractions of total organic carbon is given ( % O C )
==
5"
"--.I
Animal group/species
N
14.5 37.7 28.5 14.4 12.0 31.2 38.8 82.5 62.6 987.1 32.0 35.1 3.5 120.1 23.9 31.8 63.4 17.0 18.1
74.8 18.5 30.9 38.1 28.8 36.6 85.5 117.3 193.8 41.2 26.4 29.8 53.2 32.7 32.2 21.9 38.2 37.9 LOD LOD
2.07 45.5 0.22 1.12 0.31 2.88 1.18 0.97 1.08 3.45 0.92
1.21 5.93 1.18 0.75 0.49 1.18 1.72 4.20 61.6 1.37 1.37 1.20 0.90 1.36 0.62 1.21 0.62 1.63
A m o u n t of extracted lipid (rag):
0.46 1.28 1.04 0.95 0.94 1.34 1.45 2.09
% lipid extract
+ + + + + 5.3 + 3.2 1.18 3.04
3.0
9.5 11.1
n.d n.d + + + + 2.4
7.9
9.3 3.1
2.3 2.2 0.9 1.7 1.0 4.8 n.d 10.7 0.14 0.32
n.d 2.4 1.5 0.5 n.d 1.7 1.0 0.9 0.4 2.6
7.4 + 15.0 1.0 1.8 1.1 1.5 n.d 11.8
12.6 + 22.8 n.d 4.5 +
3.7 0.7
5.1 1.8 1.5 10.0 39.5 1.7 1.I 1.5
52
6.2 9.7
+ + + 9.7 7.5 3.2 + Z2
28
4.5 4.0 3.0 3.5 + 5.3 1.7 25.3 0.52 2.60
+ 5.5 4.0 + 5.1 4.3 + + n.d 4.1
4.1 + 10.6 + 4.2 + 1.3 2.5 30.7
5.2 0.8
7.8 2.8 + 14.9 49.2 10.0 4.5 +
101
1.1 n.d 1.9 2.6 n.d 2.6 n.d 35.3 0.19 0.49
n.d n.d 4.3 n.d 3.5 4.9 + 0.6 0.5 4.0
1.7 n.d 4.1 n.d n.d n.d 1.6 n.d 27.9
4.5 0.5
n.d 0.8 n.d. 28.1 54.5 2.3 n.d 0.9
118
5.7 3.5 1.4 3.4 2.8 9.7 2.0 52.1 0.44 1.10
2.l 6.2 5.7 2.9 6.9 15.9 7.9 1.8 2.6 7.2
2.5 1.2 39.1 2.1 7.6 2.8 2.0 4.1 24.2
4.8 1.9
6.1 4.1 3.8 29.0 65.6 6.7 4.8 2.6
153
4.9 2.6 n.d 5.9 3.3 5.5 1.8 28.5 0.40 1.06
1.1 5.3 5.8 1.5 7.2 15.7 1.3 1.3 2.1 6.3
2.0 n.d 44.6 1.6 3.9 2.4 1.8 n.d 36.4
5.0 1.0
3.3 3.4 3.9 23.3 64.4 5.1 2.1 1.7
138
Chlorinated biphenyl cogener no. (CB-):
0.6 n.d n.d n.d n.d n.d n.d 3.2 0.15 0.39
1.8 n.d 3.1 n.d 4.9 11.8 1.1 + 1.7 n.d
1.3 0.8 28.6 n.d n.d n.d 0.8 n.d 5.8
2.4 1.4
3.6 n.d 5.0 n.d 7.5 n.d 1.3 2.0
180
3.9 5.0 2.2 3.2 2.3 4.8 1.9 25.6 0.13 0.31
7.7 21.2 6.1 15.1 14.0 9.8 17.3 0.8 n.d 8.6
2.3 4.8 31.3 4.6 5.0 1.9 1.9 2.4 23.1
2.7 29.1
34.5 15.7 9.0 18.5 47.8 2.9 3.0 0.5
p,p'-DDE
In the GC runs for CB determination in samples, the % recovery of internal standard C B l 1 2 is 74.3 _+6.8; % recovery in C R M and blank runs is 93.7 _+6.0. L O D and L O Q are considered on the basis of a 1 ~tl injection from a 1 ml extract. Note: Although identified and quantified as such, the values of CB28 indicated in italic do not refer to the actual concentration of CB28, but rather reflect either c o m p o u n d s released by column bleeding or unknown components in the sample (e.g. phthalates).
South-east m o n s o o n period - - June/July Formosa Bay - - River Sabaki m o u t h 8-9/50 m Echinodermata, Ophiuridae (brittle-star) 12 03°09'S Crustacea, Penaeus sp. (tiger-prawn) 6 40°14'E Crustacea, Metapenaeus sp. (prawn) 5 Mollusca, Bivalvia, Venus sp. 40 Mollusca, Bivalvia, Anadara sp. 6 10/220 m Crustacea, Metapenaeus sp. (prawn) 10 03°10'S Crustacea, Penaeus sp. (red-prawn) 7 40°18'E Pisces, Bothidae,flatfish 5 Formosa Bay - - River Tana m o u t h 14/20 m Echinodermata, Ophiuridae (brittle-star) 6 02°42'S Pisces, Tetraodonthidae (pufferfish, liver) 7 40°31'E Kiwayu Bay 18/20 m Echinodermata, Ophiuridae (brittle-star) 15 02°04'S Crustacea, Metapenaeus sp. (tiger-prawn) 10 41°18'E Mollusca, Bivalvia, Venus sp. 4 19/50 m Crustacea, Penaeus sp. (red-prawn) 10 02°01'S Crustacea, Penaeus sp. (tiger-prawn) 10 41°20'E Crustacea, Metapenaeus sp. (prawn) 18 Crustacea, Pagurus sp. (hermit-crab) 10 Mollusca, Bivalvia, Mactra sp. 7 Mollusca, Gastropoda, Nassarius sp. 25 North-east m o n s o o n period - - N o v e m b e r / D e c e m b e r Formosa Bay - - River Sabaki m o u t h 8-9/50 m Echinodermata, Ophiuridae (brittle-star) 17 03°09'S Crustacea, Penaeus sp. (tiger-prawn) 2 40°14'E Crustacea, Metapenaeus sp. (prawn) 10 Mollusca, Bivalvia, Anadara sp. 17 Mollusca, Bivalvia, Pema viridis 9 10/220 m Crustacea, Penaeus sp. (red-prawn) 6 03°10'S Crustacea, Pagurus sp. (hermit-crab) 9 40°18'E Crustacea, Pagurus sp. ( + eggs) 7 Pagurus eggs 7 Mollusca, Cephalopoda, Sepia sp. 3 Kiwayu Bay 18/20 m Crustacea, Penaeus sp. (tiger-prawn) 12 02°04'S Crustacea, Penaeus sp. (tiger-prawn) 7 41°18'E Crustacea, Metapenaeus sp. (prawn) 7 Crustacea, Metapenaeus sp. (prawn) 5 Crustacea, Portunidae (swimming=crab) 6 Crustacea, Majidae (spider-crab) 15 Mollusca, Bivalvia, Venus sp. 10 Mollusca, Cephalopoda (Sepia sp.) 3 n.d. is not detectable; + is identified but below quantification limit.
Station # / Depth (m)/ Geographic position:
TABLE 3 Concentrations . of seven . selected . . polychlorinated . . biphenyl congeners and ,I.p,p'-DDE in macrobenthic invertebrates and two fish species_ from the coastal zone and the continental slope1_of Kenya_ .(Fig . ),1" the n u m b e r of individuals (N) m a sample of various species, the percentage lipid extracted (in mg), the absolute a m o u n t of extracted lipid (in rag) and the concentration (in ng g - extracted lipid)
Go
7=
t~
g
r~
<
Marine Pollution Bulletin 112 ISTD
i
10'
1 1,9 1 t381 i
99
I
187
52 28
44 74 49 i
1111281128 i
IR
t~ol[l~ ;/
~IUu,~.~r.,x141
~1( 118132 136
~
177
158
1,9/1~9
StandardPoychorobpheny,s./ Procedure
w
153
l
1
__~4. 9
t98 ,9,
~09 DOE
blank
5< ~ ....... \ ~'~
I 153 138
180
ill
,0,
is0
H ,~
ls3
Fig. 2 Representative capillary GC-ECD chromatograms of the polychlorinated biphenyl standard, the procedural blank and six animal species collected from the estuarine and nearby coastal zone of Formosa Bay at the River Sabaki mouth (near Malindi, Kenya): (1) Echinodermata, Ophiuridae-brittle-star; (2) Crustacea, Natantia, Penaeidae, Metapenaeus sp. - - prawn; (3) Crustacea, Natantia, Penaeidae, Penaeus sp. - - tiger prawn; (4) Crustacea, Reptantia, Paguridae, Pagurus sp, - hermit crab; (5) Mollusca, Bivalvia, A n a d a r a sp. - - cockle; and (6) Mollusca, Bivalvia, Perna viridis - - green mussel. The individual l l 2 / I S T D = C B congener 112 applied as internal standard.
498
Volume 36/Number 6/June 1998
chromatograms clearly demonstrate the presence of CB153 and p,p'-DDE. By far the highest levels of CBs were found in bivalve molluscs from the Sabaki river mouth [30 and 65 ng g-1 lipid of CB153, which is 0.29 and 0.62 ng g - 1, calculated on the basis of wet weight (ww), respectively] and Kiwayu Bay (39 ng g 1 lipid weight of CB153~0.12 ng g-1 ww), and in gastropod molluscs from Kiwayu Bay (24 ng g-1 lipid weight of CB153~0.23 ng g-1 ww). Of the cyclic pesticides, only p,p'-DDE was analyzed, and was present in all samples, in enhanced levels varying between 15 and 48 ng g lipid weight, in bivalve and gastropod molluscs. In several fish species from the Athi river estuary at Malindi (Fig. 1), which is the same area indicated here as the Sabaki river mouth, low levels of pesticides such as lindane, aldrin and DDT-family members were established by Mugachia et aI. (1992). For example, their studies revealed whole body residues ofp,p'-DDE from an average value of 10 ng g 1 wet weight (ww) in sole, to 125 ng g-1 ww (range 25-300 ng g-~) in catfish or 150ngg -1 ww (range 30-425ngg -1) in bream. p,p'-DDE constituted 92, 86 and 72% of the YDDT concentration in sole, catfish and bream, respectively (Mugachia et al., 1992). In comparison, the DDE level measured in flatfish (Bothidae) in the present work was three orders of magnitude lower viz. 0.5ngg -1 extracted lipid ( ~ 0 . 0 1 n g g -1 ww), whereas in liver from pufferfish (Tetraodonthidae) the DDE concentration was 29 ng g-1 lipid ( ~ 13.5 ng g-1 ww). However, apart from these few fish tissue samples, data reported here refer exclusively to PCBs and p,p'-DDE in macrobenthic invertebrates since, in ecological terms, they are more representative for a specific habitat or area than are (migratory) fish. The concentrations of CB congeners and p,p'-DDE in the invertebrates were substantially enhanced compared to the same groups of species sampled in the coastal zone and continental slope of the Banc d'Arguin (Mauritania), where the CB congeners 153 and 138 could not be quantified, but identified only (Everaarts et al., 1993). The levels found in benthic invertebrates from Kenyan coastal waters were two to three orders of magnitude lower than in comparable macrobenthic fauna from the shallow Java Sea and Strait Madura, the Bali basin (Indonesia) and the Java Trench (Indian Ocean) depending on the species considered (see Boon et al., 1989). For example, in penaeid prawns from the nearby coastal and estuarine zones particularly, the p,p'-DDE ranged from 100 to 4500 ng g-1 lipid weight, whereas CBs 118 and 180 ranged from 10 to 180ngg -~ and 10 to 360ngg -~ lipid weight, respectively (Boon et al., 1989). Also in comparison with other tropical estuarine systems such as along the coast of the Malay peninsula (Everaarts et al., 1991), the concentrations of CB congeners and p,p'-DDE in penaeid prawns and bivalve molluscs from the coastal zone of Kenya were 3 to 20 times lower. Harrison et al. (1996) reported p,p'-DDE levels of 0.2-1.0 ng g-1 dry weight in shell-
fish (Gafrarium tumidum) from a Pacific lagoon (Tonga). Although it was not possible to recalculate and express these levels on the basis of wet weight or extracted lipid, it can be estimated that these low levels are similar to the concentrations found in prawns and bivalves from Kenya. In a riverine mussel (Batissa violacea) from Fiji (Pacific), collected near a rice irrigation project, p,p'-DDE concentrations of 11.5 and 16.1 ngg -1 dry weight were found (Morrison et al., 1996), which are 10-fold higher than in the mussel Perna viridis from the Sabaki river mouth. In summary, the Kenyan marine environment studied here exhibited a low degree of contamination. Only in the shallow estuarine areas near the outflow of the Sabaki River, CB congeners, dieldrin, p,p'-DDD and p,p'-DDE could be quantified in enhanced levels in surface sediments. Concentrations of ~-HCH tended to increase gradually across the continental slope, while •-HCH could be detected in only a few deeper locations. The pesticides f3-HCH, endrin, p,p'-DDT and o,p'-DDT could not be identified in any of the sediment samples. In benthic invertebrates CB congeners and p,p'-DDE could be quantified, although generally, concentrations were only a factor of 2-4 above the limit of quantification. Thus, although the coastal area of Kenya is measurably impacted by discharges of rivers and by the activities of Mombasa harbor and industry, the degree of contamination is low. One of the reasons for this might be the extremely strong currents along a narrow coastal zone, both during the southeast and northeast monsoon (Anon, 1991), causing a very short residence time of particles (including adsorbed or lipid associated organic contaminants) in the coastal waters. Atmospheric transport might be responsible for enhanced levels of HCHs in offshore areas. The data reflected the interspecific differences in uptake and accumulation of CB congeners and p,p'-DDE. In bivalve and gastropod molluscs relatively high levels of CBs and p,p'-DDE were established, but similar values were also found in edible penaeid prawns. However, none of the samples had residue levels of PCBs or pesticides above the extraneous residue limits (ERL) and acceptable daily intake (ADI) set by the FAO/WHO Codex Alimentarius Commission (1986). With respect to human health, the concentrations of all of the PCBs and pesticides measured, both in bivalve moluscs and crustaceans, were far below the maximum admissible concentration (MAC). For example, in fishery products for human consumption, the MAC value for ~]DDT, ~- and ~-HCH, dieldrin and CB153 is 500, 50, 50 and 100 ng g-1 ww, respectively (Van der Valk, 1989). These values agree with the values for acceptable (daily) intake, which are based on WHO standards and take into account the general consumption pattern. This research has been carried out as a part of the Netherlands Indian Ocean Program 1990-1995, Project A, Monsoons and Coastal
499
Marine Pollution Bulletin Ecosystems in Kenya. The programme was organized and funded by the Netherlands Marine Research Foundation (SOZ) of the Netherlands Organization for Scientific Research (NOW). Special thanks are due to Captain J. de Jong and the late Captain kJ. Blok and their crew of the R.V. Tyro, and the technicians on board during the surveys. Thanks are also due to R. Kloosterhuis for performing the analyses of total organic carbon, and M. Lavaleye for the determination of the benthic species. This is Publication number 3101 of the Netherlands Institute of Sea Research. Anon (1984) PCB regulation. Dutch Staatscourant, The Hague, The Netherlands. Anon (1988) Verordnung fiber H6chstmengen an Schadstoffen in Lebensmitteln Bundesgesetzblatt, Teil 1. Bonn, Germany, pp. 422-424. Anon (1991) Netherlands Indian Ocean Program 1990/1995. Scientific Program Plan. Netherlands Marine Research Foundation, The Hague, pp. 1-118. Ballschmiter, K. and Zell, M. (1980) Analysis of polychlorinated biphenyls (PCB) by glass capillary gas chromatography. Composition of technical arochlor and clophen-PCB mixtures. Fresenius' Z. Anal. Chem., 302, 20-31. Bligh, E. G. and Dyer, W. J. (1959) A rapid method of total lipid extraction and purification. Can. J. Biochem. Physiol., 37, 911-917. Boon, J. P., Everaarts, J. M., Kastoro, W., Razak, W., Sumanta, I., Sumarno, Nelissen, P. H., .Stefels, J. and Hillebrand, M. Th. J. (1989) Cyclic organochlorines in epibenthic organisms from coastal waters around East Java. Neth. J. Sea Res., 23, 427-439. De Boer, J. and Dao, Q. T. (1991) Analysis of seven chlorobiphenyl congeners by multidimensional gas chromatography. J. High Resolut. Chromatogr., 14, 593-596. De Boer, J. and Wells, D. E. (1996) The 1994 QUASIMEME laboratory-performance studies: .chlorobiphenyls and organochlorine pesticides in fish and sediment. Marine Pollut. Bull., 32, 654-666. Dninker, J. C. and Hillebrand, M. Th. J. (1978) Minimizing blank values in chlorinated hydrocarbon analysis. J. Chromat., 150, 195-199. Duinker, J. C. and Hillebrand, M. Th. J. (1983) Characterization of PCB components in clophen formulations by capillary GC-MS and GC-ECD techniques. Environ. Sci. TechnoL, 17, 449-456. Everaarts, J. M. and Nieuwenhuize, J. (1995) Heavy metals in surface sediment and epibenthic macroinvertebrates from the coastal zone and continental slope of Kenya. Marine Pollut. Bull., 31, 281-289. Everaarts, J. M., Bano, N., Swennen, C. and Hillebrand, M. Th. J. (1991) Cyclic chlorinated hydrocarbons in benthic invertebrates from three coastal areas in Thailand and Malaysia. J. Sci. Soc. Thailand, 17, 31-49. Everaarts, J. M., Heesters, R., Fischer, C. V. and Hillebrand, M. T. J. (1993) Baseline levels of cyclic pesticides and PCBs in benthic invertebrates from the continental slope of the Banc d'Arguin (Mauritania). Marine Pollut. Bull., 26, 515-521.
500
FAO/WHO Codex Alimentarius Commission, 1986. Codex maximum limits for pesticide residues, 2nd edn. Grobler, D. F., Badenhorst, J. E. and Kempster, P. L. (1996) PCBs, chlorinated hydrocarbon pesticides and chlorophenols in the Isipingo estuary, Natal, Republic of South Africa. Marine Pollut. Bull., 32, 572-575. Harrison, N., Gangaiya, P. and Morrison, R. J. (1996) Organochlorines in the coastal marine environment of Vanuata and Tonga. Marine Pollut. Bull., 32, 575-579. Holden, A. V. and Marsden, K. (1969) Single-stage clean-up of animal tissue extracts for organochlorine residue analysis. J. Chromat., 44, 481-492. Morrison, R. J., Harrison, N. and Gangaiya, P. (1996) Organochlorine contaminants in the estuarine and coastal marine environments of the Fiji islands. Environ. Pollut., 93, 159-167. Mugachia, J. C., Kanja, L. and Maitho, T. E. (1992) Organochlorine pesticide residues in estuarine fish from the Athi river. Kenya BulL Env. Contam. Toxicol., 49, 199-206. Preston, M. R. (1988) In: Riley, J. P. (Ed.), Marine Pollution. Chemical Oceanography, Vol. 9. Academic Press, London, pp. 54-196. Sarkar, A. and Sen Gupta, R. (1991) Pesticide residues in sediments from the west coast of India. Marine Pollut. Bull., 22, 42-45. Sarkar, A., Sen Gupta, R. (1993) On chlorinated hydrocarbons in the Indian Ocean. In: Desai, B.N. (Ed.), Oceanography of the Indian Ocean. A. A. Balkema, Rotterdam, The Netherlands, pp. 385-395. Schulz, D. E., Petrick, G. and Duinker, J. C. (1989) Complete characterization of polychlorinated biphenyl congeners in commercial arochlor and clophen mixtures by multidimensional gas chromatography-electron capture detection. Environ. Sci. Technol., 23, 852-859. Shailaja, M. S., Sarkar, A. (1993) Organochlorine pesticide residues in the northern Indian Ocean. In: Desai, B. N. (Ed.), Oceanography of the Indian Ocean. A.A. Balkema, Rotterdam, The Netherlands, pp. 379-383. UNEP/IAEA/IOC/FAO (1992) Organohalogen compounds in the marine environment: a review. MAP Technical Reports Series 70, United Nations Environmental Programme, Athens. Van der Valk, F. (1989) Overview of standards for contaminants in fishery products. Report of the Working Group on Environmental Assessments and Monitoring Strategies, Brest, France, 24-28 April 1989. International Council for the Exploration of the Seas, Copenhagen, pp. 43-46. Wells, D. E., De Boer, J., Tuinstra, L. G. M. T., Reuterg~rdh, L. and Griepink, B. (1998) Improvements in the analysis of chlorobiphenyls prior to the certification of seven CBs in two fish oils. Fresenius' Z. AnaL Chem., 332, 591-597. Williams, T. M., Rees, J. G., Ferguson, A., Herd, R. A., Kairu, K. K. and Yobe, A. C. (1997) Metals, petroleum hydrocarbons and organocblorines in inshore sediments and waters of Mombasa, Kenya. Marine Pollut. Bull., 0, 0 (in press).