Occurrence of organochlorine pesticides, polychlorinated biphenyls ...

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c Institute of Zoology, Academia Sinica, Nonkang 115, Taipei, Taiwan. The deep-sea ..... (Voorspoels et al., 2003); coastal fishes from Florida (John- son-Restrepo et .... Aid for Scientific Research (A) (16201014) from Japan ... Financial support was also provided .... Environmental Science and Technology 34, 5129–5136.
Baseline / Marine Pollution Bulletin 52 (2006) 1784–1832

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Occurrence of organochlorine pesticides, polychlorinated biphenyls and polybrominated diphenyl ethers in deep-sea fishes from the Sulu Sea Karri Ramu a, Natsuko Kajiwara a, Hiroko Mochizuki a, Hitoshi Miyasaka a, Kwadwo Ansong Asante a, Shin Takahashi a, Suguru Ota b, Hsin-Ming Yeh c, Shuhei Nishida b, Shinsuke Tanabe a,* a

Center for Marine Environmental Studies (CMES), Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577, Japan b Ocean Research Institute, University of Tokyo, Minamidai 1-15-1, Nakano, Tokyo 164-8639, Japan c Institute of Zoology, Academia Sinica, Nonkang 115, Taipei, Taiwan

The deep-sea regions encompass about 75% of the biosphere. Despite their remoteness, these regions are reached by a diverse group of anthropogenic pollutants such as the persistent organic pollutants (POPs). The sources of POPs to the marine environment are riverine transport, municipal and industrial discharges, continental runoff and long-range atmospheric transport. Once in the marine environment, POPs adsorb to the detritus and marine snow and are eventually carried to the deep-sea where they biomagnify in the food web (Froescheis et al., 2000). Numerous studies have demonstrated that concentrations of POPs in organisms living in the deep-sea are considerably higher than in organisms living in the surface ocean (Berg et al., 1997, 1998; Lee et al., 1997; Takahashi et al., 1998, 2000, 2001; Looser et al., 2000; Froescheis et al., 2000; Sole´ et al., 2001; de Brito et al., 2002; Mormede and Davies, 2003; Storelli et al., 2004; Tanabe et al., 2005). Therefore, the study on the occurrence and fate of POPs in deep-seas is of special interest. The area of study, the Sulu Sea is an isolated marginal basin (250 000 km2) in the western Pacific Ocean, located between the Philippine Islands and Sabah (Borneo) and is surrounded by sills which are generally less than 200 m deep (Rathburn and Miao, 1995). The shallow sill depths and other straits prevent deep water of the Sulu Sea from communicating with that of the other deep-sea basins and thus the Sulu Sea is ideal to study vertical processes of physical mixing and biogeochemical cycling that govern the elemental distributions in the water column (Nozaki et al., 1999). No information exists on organochlorines (OCs) contamination in deep-sea ecosystem of the Sulu Sea. In addition to OCs contamination, aquatic pollution resulting from widespread usage of polybrominated diphenyl ethers (PBDEs) as flame retardants deserves concern because of their bioaccumulation potential, persistence and endocrine disrupting effects. Studies addressing the contamination of deep-sea areas by PBDEs are scarce.

*

Corresponding author. Tel./fax: +81 89 927 8171. E-mail address: [email protected] (S. Tanabe).

The fact that the deposited POPs are a threat to deep-sea ecosystems and their transfer to the deep ocean is of concern, the present study attempted to investigate the occurrence of OCs such as polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), chlordane-related compounds (CHLs), hexachlorocyclohexane isomers (HCHs), hexachlorobenzene (HCB) and PBDEs in deep-sea fishes from the Sulu Sea. Furthermore, food chain magnification of organohalogen compounds was examined using stable isotopes of nitrogen and carbon as continuous measures of trophic position. Various deep-sea fishes from depths ranging from 292 to 1015 m were collected from the Sulu Sea during November–December, 2002, with either a mid-water trawl, plankton net, or a beam trawl. Sampling location and biological information of the samples are shown in Fig. 1 and Table 1, respectively. Twenty-two specimens belonging to eight species were analyzed for organohalogen compounds. The whole body of individual specimens belonging to the same species collected from the same sampling location were pooled and homogenized to prepare a composite sample which was employed for chemical analysis. OCs including PCBs, DDTs, HCHs, CHLs and HCB were analyzed following the method described by Kajiwara et al. (2003). Briefly, 20 g of the pooled homogenized tissue sample was ground with anhydrous sodium sulfate and extracted in a Soxhlet apparatus with a mixture of diethyl ether and hexane for 7–8 h. An aliquot of the extract was added to a gel permeation chromatography (GPC; BioBeads S-X3, Bio-Rad Laboratories, CA, 2-cm i.d. and 50 cm length) column for lipid removal. The GPC fraction containing OCs was concentrated and passed through an activated Florisil column for clean-up and fractionation. Quantification of PCBs and OCs was performed using GC (Agilent 6890N) equipped with a micro-electron capture detector (micro-ECD) and an auto-injection system (Agilent 7683 Series Injector). The GC column used for OC analysis was a fused silica capillary (DB-1; 30 m · 0.25 mm i.d. · 0.25 lm film thickness, J&W Scientific Inc.). The concentration of individual OCs was quantified from the peak area of the sample to that of the corresponding external standard. The PCB standard used for

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Baseline / Marine Pollution Bulletin 52 (2006) 1784–1832

Fig. 1. Map showing the sampling locations of deep-sea fishes from the Sulu Sea. The black dots indicate sampling locations.

Table 1 Sample details of deep-sea fishes from the Sulu Sea Sample ID

Family

Species

n

Sampling depth (m)

Mean length (mm)

Mean weight (g)

Habitat

Sulu-1 Sulu-3 Sulu-4 Sulu-6 Sulu-7 Sulu-8 Sulu-9 Sulu-11 Sulu-13 Sulu-15

Zenionidae Alepocephalidae Macrouridae Alepocephalidae Ophidiidae Alepocephalidae Anguilliformes Acropomatidae Ophidiidae Setarchidae

Zenion hololepis Rouleina sp. Bathygadus sp. Rouleina sp. Lamprogrammus niger Rouleina sp. Synaphobranchus brevidorsalis Malakichthys elegans Glyptophidium japonicum Lioscorpius longiceps

3 3 2 2 1 1 1 3 3 3

514–516 688–693 796–804 796–804 1012–1015 1012–1015 1012–1015 292–296 367–368 367–368

106 173 223 NA 316 197 423 100 155 117

24 35 25 34 140 48 120 11 14 15

Bathydemersal Bathypelagic Bathypelagic Bathypelagic Bathypelagic Bathypelagic Bathydemersal Bathydemersal Benthopelagic Bathydemersal

NA: not available.

quantification was a mixture of 62 PCB isomers and congeners (BP-MS) obtained from Wellington Laboratories Inc., Ontario, Canada. Concentrations of individually resolved peaks of PCB isomers and congeners were summed to obtain total PCB concentrations. Analysis of PBDEs was performed following the procedure described by Ueno et al. (2004) with slight modification. An aliquot of the extract, after adding 5 ng of internal standards (13C12-labeled BDE-3, BDE-15, BDE28, BDE-47, BDE-99, BDE-153, BDE-154, BDE-183, BDE-197, BDE-207 and BDE-209), was added to GPC. The GPC fraction containing organohalogens was concentrated and passed through 1.5 g of activated silica gel (Wakogel S-1: Wako Pure Chemical Industries Ltd., Japan) column with 5% dichloromethane in hexane for

clean-up. 13C12-labled BDE-139 was added to the final solution prior to gas chromatograph equipped with a mass-selective detector (GC–MSD) analysis. Quantification was performed using a GC (Agilent 6890N) equipped with MSD (Agilent 5973N) for mono- to hepta-BDEs, and GC coupled with MS (JEOL GCmate II) for octa- to decaBDE, having an electron impact with selective ion monitoring (EI-SIM) mode. GC columns used for quantification were DB-1 fused silica capillary (J&W Scientific Inc.) having 30 m · 0.25 mm i.d. · 0.25 lm film thickness for monoto hepta-BDEs, and 15 m · 0.25 mm i.d. · 0.1 lm film thickness for octa- to deca-BDE. Fourteen major congeners of PBDEs (BDE-3, BDE-15, BDE-28, BDE-47, BDE99, BDE-100, BDE-153, BDE-154, BDE-183, BDE-196, BDE-197, BDE-206, BDE-207 and BDE-209) were quanti-

Baseline / Marine Pollution Bulletin 52 (2006) 1784–1832

fied in this study. All the congeners were quantified using the isotope dilution method to the corresponding 13C12labeled congener. Recovery of 13C12-labeled BDE ranged between 60% and 120%. Procedural blanks were analyzed simultaneously with every batch of five samples to check for interferences or contamination from solvents and glassware. Lipid contents were determined by measuring the total nonvolatile solvent-extractable material on sub samples taken from the original extracts. The concentrations of organohalogens are expressed on lipid weight basis unless otherwise specified. Sub samples from the homogenized samples were dried for 24 h at 60 C and ground into powder with a mortar and pestle. The solvent-extractable lipid fraction was removed from the sub sample by extraction with a mixture of chloroform:methanol (2:1), and the lipid free residues were centrifuged using micro-tubes and dried at room temperature and later at 60 C for 24 h. One mg powder sub samples were packed into 4 · 6 mm tin capsules for stable isotope measurements. The stable isotope ratios of carbon (d13C) or nitrogen (d15N) were measured using a mass-spectrometer (ANCA-SL, PDZ Europe Inc.). The ratio was expressed by d notation as parts per thousand (&) differences from the standard: d13 C; d15 N ¼ ðRsample =Rstandard  1Þ  1000 where R = 13C/12C or 15N/14N. Pee Dee Belemnite (PDB) limestone carbonate and atmospheric nitrogen (N2) were used as standards for carbon and nitrogen isotopic ratios, respectively. Analytical precision was better than ±0.01&. 15 L-Histidine (d N = 7.81&) was used as the reference material.

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The organohalogen residue levels found in deep-sea fishes from the Sulu Sea are shown in Tables 2 and 3. Among the organohalogen compounds analyzed, concentrations of DDTs and PCBs were the highest, and those of the other compounds were approximately in the order of CHLs > HCHs P HCB > PBDEs. The predominance of DDTs and PCBs in the deep-sea fishes from the Sulu Sea is alike to those in deep-sea fishes from Suruga Bay, Japan (Lee et al., 1997); Tosa Bay, Japan (Takahashi et al., 2001); Western North Pacific, off-Tohoku, Japan (de Brito et al., 2002) and the East China Sea (ECS) (Tanabe et al., 2005). This may be due to the higher bioaccumulative properties of these compounds and the continuous release of these compounds into the environment. Levels of HCB were low and comparable to HCH concentrations. The Sulu Sea lies within the subequatorial and equatorial zones with annual minimum temperatures of >20 C (De Vantier et al., 2004). The high surface water temperatures could lead to volatilization of the highly volatile OCs such as HCHs and HCB and hence result in lower levels, while higher molecular weight OCs such as PCBs, DDTs and CHLs have high affinity to particulate matter and thus get transported to deep waters. Further, to understand the current status of OCs pollution in deep-sea fishes from the Sulu Sea, residue levels found in the present study were compared with studies carried out in adjoining areas on deep-sea fishes by our group (Table 4). The relatively low contamination by OCs in the present study area might be due to the smaller usage of these compounds in this region compared to that of the other locations. In addition to this, factors like variations in fish species, different sampling seasons and size groups compared in Table 4 may also influence the differences in the OCs levels. Low levels of OCs have also been reported

Table 2 Concentrations of organochlorines (ng/g lipid wt.) in deep-sea fishes from the Sulu Sea Sample ID

Species

Lipid (%)

d15N (&)

d13C (&)

DDTs

PCBs

CHLs

HCHs

HCB

Sulu-1 Sulu-3 Sulu-4 Sulu-6 Sulu-7 Sulu-8 Sulu-9 Sulu-11 Sulu-13 Sulu-15

Zenion hololepis Rouleina sp. Bathygadus sp. Rouleina sp. Lamprogrammus niger Rouleina sp. Synaphobranchus brevidorsalis Malakichthys elegans Glyptophidium japonicum Lioscorpius longiceps

2.0 0.95 0.42 0.50 0.48 0.53 5.0 2.6 0.62 1.3

11.65 12.45 13.19 12.51 11.65 11.95 11.56 10.3 11.68 10.33

17.91 18.1 17.47 16.6 17.79 17.3 17.25 17.31 17.87 16.13

150 160 210 110 120 270 69 150 140 140

44 64 79 51 49 110 19 35 69 55

17 5.8 17 6.0 11 10 8.6 17 5.1 14

6.1 5.3 7.4 6.9 9.3 7.4 3.0 5.2 10 7.9

8.4 5.8 6.0 6.4 1.3 4.2 7.1 13 7.9 8.2

Table 3 Concentrations of PBDEs (ng/g lipid wt.) in deep-sea fishes from the Sulu Sea Sample ID

Species

Depth (m)

Lipid (%)

BDE-28

BDE-47

BDE-99

BDE-100

BDE-154

Total

Sulu-1 Sulu-3 Sulu-4 Sulu-6 Sulu-7 Sulu-9

Zenion hololepis Rouleina sp. Bathygadus sp. Rouleina sp. Lamprogrammus niger Synaphobranchus brevidorsalis

514–516 688–693 796–804 796–804 1012–1015 1012–1015

2.0 0.95 0.42 0.50 0.48 5.0

0.12