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Levels of chlorinated hydrocarbons and trace metals in bivalves and nearshore sediments from the Dominican Republic
Pergamon PIh S0025-326X(98)00097-6
Marine Pollution BuUetm. Vol. 36, No, 12, pp. 971-979, 1998 © 1998 Elsevier Science Ltd. All rights reserved Printed in Great Britain (~)25-326X/98/$19.1~1+0,0()
Levels of Chlorinated Hydrocarbons and Trace Metals in Bivalves and Nearshore Sediments from the Dominican Republic L U C I A N O SBRIZ*, M A R G A R I T A R. A Q U I N O ? , NAT1VIDAD M. A L B E R T O DE R O D R I G U E Z ~ , S C O T T W. F O W L E R § and JOSE L. SERICANO¶II
*Comisi6n Nacional de Asuntos Nucleares (CONAN), Calle Coronel Fernandez Dominguez 30-A, Apartado Postal 30333, Ens. La Fe, Santo Domingo, D.N., Rep(lblica Dominicana tDepartamento de Quimica, Universidad Nacional Pedro Henriquez Urena, Santo Domingo, D.N., Rep(tblica Dominicana ~Instituto de Fisica, Universidad Aut6noma de Santo Domingo, Santo Domingo, D.N., Rep~blica Dominicana §IAEA Marine Environment Laboratory, 19 av. des Castelans, B.P. 800, MC-98012, Monaco Cedex Monaco ¶Geochemical and Environmental Research Group, TexasA&M University, 833 Graham Rd, College Station, TX 77845, USA Bivalves (Crassostrea rizhophorae, Isognomon alatus, Codakia orbicularis Linn~, and Tellina fausta) and sediment samples collected from 12 locations along the Dominican Republic coastline were used to assess the degree of nearshore contamination by selected chlorinated hydrocarbons and heavy metals. Concentrations of total chlordanes, DDTs and PCBs ranged from 0.51 to 7.47 ng/g, < MDL to 30.9 ng/g and 11.3 to 82.3 ng/g, and from < M D L to 1.73 ng/g, 0.21 to 12.5 ng/g and 0.46 to 41.9 ng/g in bivalves and surface sediments, respectively. The concentration ranges of predominantly anthropogenic Cu, Pb and Zn were 3.08866 llg/g, 0.08-1.46 llg/g and 22.9-4380 I~g/g in bivalve soft parts and 1.01-111mg/g, 0.420-1341~g/g and 1.96-277 l~g/g in surface sediments, respectively. Mercury concentrations ranged from 0.290 to 7.02 lag/g and from 0.096 to 0.565 l~g/g in both matrices. The relatively high Hg concentrations found in bivalves from two stations in Bahia Samana, near to a known source of past Hg contamination in the sediments, require a more in-depth survey of the area. In general the concentrations of selected chlorinated hydrocarbons and trace metals, compared with those reported for the same matrices in the Caribbean and west Atlantic coastal areas, show at present the existence of only very localized contamination problems in the Dominican Republic. © 1998 Elsevier Science Ltd. All rights reserved
worldwide. The Dominican Republic is not an exception in this context. Marine contamination is becoming a national issue in this Caribbean country as a result of growing industrial and agricultural activities. The rapid, and somewhat uncontrolled, growth of these activities in the Dominican Republic makes it necessary to have an adequate action plan to protect the environment, particularly the nearshore coastal zone. Besides the need to keep the fauna free of contaminants for local human consumption, the warm and clear tropical waters surrounding the Dominican Republic are of vital importance for the island and its policy to promote and encourage tourism. Even though the contaminant inputs into the environment through industrial and agricultural activities are well known in the Dominican Republic, a monitoring programme has not yet been established to evaluate the present status of contamination. Such an effort is important to derive baseline levels to evaluate future trends in the concentration of different contaminants and their potential impact on the coastal environment. The main objective of this project was to establish a local environmental monitoring network which uses sediments and bioindicator species to assess trends of selected chlorinated hydrocarbons (e.g. pesticides and PCBs) and heavy metal contaminants in coastal areas of the Dominican Republic.
The contamination of the coastal marine environment is a problem of concern for scientists and politicians
Sampling and Sample Preparation
]lAuthor for c o r r s p o n d e n c e .
For the initial survey, 14 locations around the island were selected for sampling (Fig. 1). In general, access to the coastal sampling sites was by road; however, in 971
Marine Pollution Bulletin
instances where a vessel was required to reach the site, a boat was provided by the Comisi6n Nacional de Asuntos Nucleares (CONAN). Although an attempt was made to obtain samples from every preselected site, this was not always possible. Fine-grained sediments were not found in Bahia de Ocoa, Montecristi and Nagua. Furthermore, bivalves were not found in Pedernales, Bahia de Ocoa, Santo Domingo, Puerto Plata and Nagua. In general, the sampling strategy followed that used for the NOAA's National Status and Trends Program in the US (Sericano et al., 1990). Bivalves (n = 20) and sediment samples were collected over a 2-week period in August 1995 from 9 and 11 sites, respectively, and analysed for a selected suite of chlorinated pesticides, polychlorinated biphenyls (PCBs) and trace metals. The sampling locations were selected to provide a broad coverage of Dominican Republic coastline including potential point sources of contamination. The general sampling criteria included the collection of sediments and organisms beyond the zone of initial dilution of wastes or suspected point-source discharges of contaminants. Sediment samples were collected mainly in areas containing fine-grained sediments. In most cases, sampling of bivalves was limited to natural substrates (e.g. rocks, roots of mangroves or mud) to avoid any inadvertant contamination. In a few 72 °
,o°1
instances, however, bivalves were only found attached to artificial structures (e.g. pilings). In these cases, samples were collected and the type of artificial structure recorded for future reference. Sediment samples for trace metals were either collected by hand, with the use of a clean plastic spoon, or using a box corer. Subsamples from the centre of the box corer were taken with the use of a clean plastic spoon. Sediment samples for organic contaminants were collected with the use of a solvent-rinsed metal spoon. Bivalves were collected by hand in intertidal or shallow subtidal areas. Bivalve samples were processed in the laboratory in Santo Domingo, usually within 24 h of collection, by shucking them using a precleaned plastic knife for metals, and an oyster knife for trace organics. Sediment and bivalve samples destined for trace-metal analysis were placed in plastic Ziploc bags while samples for trace-organic analysis were placed in precombusted glass jars with Teflon-lined caps.
Analytical Methods Chlorinated hydrocarbons The analytical procedure used in the extraction, fractionation and clean-up of chlorinated pesticides and PCBs in bivalves and sediment samples has been described elsewhere (Sericano et al., 1990). Briefly,
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SAMPLING 1 2 3 4 5 6 7
11
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LOCATIONS
Montecristi (O) Puerto Plat,, (S) Rio San Juan (S/O) Nagua Samana (S/O) Sanchez(S/O) Sabana de la Mar iS/O) S = sediments
8 9 10 11 12 13 14
Miches(S/O) Isla Saona (S/O) San Pedro (S/O) S~mtoDomingo(S) Bahiade Ocoa Barahona (S/O) Pedernales[SI 0 = organisms
DOMINICAN REPUBLIC I •
2,0
• 0
e e 20
Fig. 1 Sediment and bivalve sampling locations in the Dominican Republic.
972
40 a 40
60 MI 60 KM
Volume 36/Number 12/December 1998 approximately 15g of wet tissue and 20g of wet sediment were extracted, after the addition of anhydrous NazSO4, with methylene chloride using a homogenizer and Soxhlet apparatus, respectively. Before extraction, 4,4' dibromooctafluorobiphenyl (DBOFB), PCB 103 and PCB 198 were added to all samples, blanks and reference material as internal standards. Each set of 8-10 samples was accompanied by a complete system blank, spiked blank and reference material that were carried through the entire analytical method as part of the laboratory quality assurance/quality control (QA/QC) procedure. Tissue and sediment extracts were fractionated by partially deactivated silica:alumina column chromatography. The sample extracts were eluted from the column using a 1:1 mixture of pentane and methylene chloride. The tissue fraction was further purified by high-performance liquid chromatography to remove lipids. The sample extracts were finally concentrated to a volume of 1 ml in hexane for gas chromatographic analysis. Chlorinated pesticides and polychlorinated biphenyls were analysed by gas chromatography using an electron capture detector (ECD) and a 30-m narrow bore, fused-silica column with DB-5 as the bonded phase. The column temperature was programmed at 100°C for 1 min, increasing at 5°Cmin -1 to 140°C, held for 1 min, increasing at 1.5°C min -I to 250°C, held for 1 min, and increasing at 10°C min -1 to 300°C with a final hold of 5 min. The injector and detector temperatures were set at 275 and 325°C, respectively. Helium and a mixture of argon:methane (95:5%) were used as the carrier and make-up gases, respectively. The instrument was calibrated by injection of the standard component mixtures at four different concentrations prior to the analysis of the samples.
Trace metals Atomic absorption spectrophotometry by flame or graphite furnace was used to analyse all metals except Hg. Mercury was analysed by cold vapour atomic absorption spectrometry. Specific details of the methods used for trace-metal analyses have been reported elsewhere for bivalves (UNEP, 1984; Bloom, 1992; Fowler et al., 1993) and sediments (Bloom and Crecelius, 1987; Liang and Bloom, 1993, UNEP/IAEA/ IOC, 1995). Briefly, subsamples of bivalve soft parts were lyophilized, ground to a fine powder, and homogenized. The homogenized tissues were then dissolved in concentrated nitric acid. Sediment samples were lyophilized and fractions <63 gm separated by nylon sieves. For sediment sample digestion - 0.1-0.3 g of the < 63-gm fractions were microwaved in closed Teflon bombs with hydrofluoric acid (HF) in combination with aqua regia. The use of HF is essential since it is the only acid that completely dissolves the silicate lattices and releases all metals. Total mercury was analysed by digesting the sediment samples (0.2-0.3 g) with a mixture of concentrated
nitric acid and sulfuric acid at room temperature for up to 12 h (cold digestion) followed by digestion at 100°C for 3 h. Mercury present in the samples was first reduced to its elemental state with sodium borohydride, and the mercury vapour was then passed through a quartz absorption cell of an atomic absorption spectrometer where its concentration was measured and recorded. Reagent blanks and standard reference materials (SRMs) were prepared and digested for each batch of samples as part of the laboratory internal QA/QC procedures.
Ancillary parameters The organic carbon content (OC%) of the sediment samples was determined by wet oxidation with potassium dichromate and concentrated sulfuric acid followed by titration with ammonium sulfate. Calcium carbonate content (CaCO3%) in the sediments was determined by gravimetry after treatment of the samples with excess hydrochloric acid (e.g. Loring and Rantala, 1992; UNEP/IAEA/IOC, 1995).
Results and Discussion Chlorinated hydrocarbons The concentrations of a selected suite of chlorinated pesticides and PCBs measured in sediments and bivalve samples are listed in Table 1 and Table 2, respectively. Concentrations of individual chlorinated pesticides in sediments ranged from less than the corresponding Method Detection Limit (MDL) to 6.04ng/g. The most abundant chlorinated pesticide residues encountered in these samples were DDT and its metabolites, DDE and DDD. Concentrations of total DDT (i.e. sum of o - p ' and p-p' isomers of DDT, DDE and DDD) ranged from < MDL at a site located near the border between the Dominican Republic and Haiti (Pedernales) to 12.5ng/g in Puerto Plata. A concentration of 7.80 ng/g was measured in the vicinity of the capital city Santo Domingo. Similarly, the highest total chlordane concentrations were encountered near these two cities (1.71 and 1.41 ng/g, respectively). Other chlorinated pesticides occasionally encountered in sediments were dieldrin and mirex. Most of the pesticide analytes in sediment samples, however, were undetected. Concentrations of PCBs, expressed as the sum of individual congeners, were generally higher than levels observed for pesticides and ranged from 0.46 to 41.9 ng/g. The highest concentrations were measured in sediments collected from heavily inhabited locations or areas with significant port and/or industrial activities, e.g. Santo Domingo (41.9 ng/g) and Puerto Plata (25.3 ng/g). The same suite of chlorinated pesticides and PCBs was also determined in bivalves. The concentration of total DDTs in total soft tissue ranged from < M D L in samples from Isla Saona, on the extreme eastern shore of the Dominican Republic, to 30.9 ng/g in Barahona 973
Marine Pollution Bulletin
located on the southern coast of the island. A similar high concentration was encountered in bivalves from Miches (30.2 ng/g). The average contribution of DDTs, DDDs and DDEs to the total DDT load observed at those sites where both sample types were collected were different in bivalves (5.0, 17.0 and 78.0%, respectively) compared with sediments (20.4, 35.1 and 44.5%, respectively). Total chlordane concentration was highest in the bivalves collected near Samana (7.47 ng/g). Other chlorinated pesticides occasionally encountered in bivalve samples were dieldrin, aldrin, endrin, hexachlorocyclohexane isomers and mirex. Concentrations of PCBs were generally higher in bivalves collected near large industrialized areas and/or ports (e.g. Barahona, Puerto San Pedro and Samana) and lower in samples collected from more remote areas (e.g. Isla Saona). PCB congeners are also distri-
buted differently in bivalves compared with sediments. In general, bivalves preferentially accumulate congeners with four, five and six chlorine atoms. This preferential uptake by bivalves has been extensively discussed elsewhere (e.g., Sericano, 1993; Sericano et al., 1996). As expected, bivalves were found to accumulate chlorinated pesticides and PCBs to concentrations significantly higher than those in sediment from the same sampling location. For example, the average ratios of total DDT, PCB and chlordane concentrations in bivalve tissues to sediment samples from the same location were 20 (2-70), 7 (1-10) and 15 (2-45), respectively. The general geographic distribution of concentrations along the coast, however, corresponded well. Dieldrin, for example, was only detected in significant amounts in one oyster sample collected near Miches (10.4 ng/g) which corresponded to the highest
TABLE 1
Chlorinated hydrocarbon concentrations (n~g, dry wt) in sediment samples from the Dominican Republic.
Location Station #
Puerto Plata 2
Rio San Juan 3
Samana 5
Sanchez 6
Sabana de la Mar 7
Miches 8
Isla Saona 9
San Pedro 10
Santo Domingo 11
Barahona 13
Pedernales 14
Hexachloronbenzene Alpha H C H Beta H C H Gamma HCH Delta H C H Heptachlor Heptachlor epoxide Oxychlordane G a m m a chlordane Alpha chlordane Trans-Nonachlor Cis-Nonachlor Aldrin Dieldrin Endrin Mirex 2,4' D D E 4,4' D D E 2,4' D D D 4,4' D D D 2,4' D D T 4,4' D D T PCB8/5 PCB18/17 PCB28 PCB52 PCB44 PCB66 PCB101/90 PCB118 PCB153/132 PCB105 PCBI38/160 PCBI87 PCB128 PCB180 PCB195/208 PCB206 PCB209 Total H C H s Total chlordanes Total D D T s Total PCBs
0.03 J nd nd 0.06 J nd nd nd 0.15 1.05 nd 0.23 0.30 nd 0.13 nd 0.19 0.21 6.04 1.80 3.70 nd 0.74 0.41 nd 1.60 1.62 0.68 1.23 1.60 0.90 1.07 0.27 0.86 nd 0.58 nd nd nd 0.76 0.06 J 1.73 12.5 25.3
0.03 J nd nd nd nd nd nd nd 0.07 J 0.06 J 0.11 J 0.16 nd nd nd 0.30 0.07 J 2.23 0.12 J 0.75 nd nd nd 0.11J nd 0.31 J nd nd 0.15 J 0.06 J nd nd 0.42 nd 0.18 J 0.28 0.05 J nd nd nd 0.40 3.17 3.44
0.02 J nd nd nd nd nd nd nd 0.14 J 0.09 0.04 J 0.07 nd 0.09 nd 0.03 J 0.02 J 0.73 0.31 0.61 nd 0.10 0.48 0.12J 0.39 0.24 J 0.17 0.23 0.09 J 0.10 0.16 0.05 J 0.15 nd 0.03 J 0.10 nd nd nd nd 0.35 1.77 5.07
0.02 J nd nd nd nd nd nd nd 0.02 J nd 0.02 J 0.02 J 0.03 J 0.01 J nd 0.02 J 0.07 0.15 nd 0.07 nd nd nd 0.02J nd 0.07 J 0.03 J nd 0.04 J nd nd nd 0.02 J nd nd 0.18 nd nd 0.01 J nd 0.06 J 0.30 0.82
0.07 J nd nd nd nd nd nd nd nd nd 0.05 J 0.02 J nd nd nd nd 0.08 0.08 nd 0.05 J nd nd nd 0.02J nd nd nd nd 0.04 J nd nd nd 0.03 J nd nd 0.11 nd nd 0.01 J nd 0.07 J 0.21 0.46
0.04 J nd nd nd nd 0.03 J nd nd 0.05 J 0.02 J 0.03 J 0.05 0.07 J 1.38 nd nd nd 0.84 0.12 J 0.87 nd 0.22 nd 0.17J 0.02 J 0.17 J nd 0.03 J 0.05 J nd nd nd 0.09 0.09 J nd nd nd nd nd nd 0.18 2.05 1.34
0.02 J nd nd nd nd nd nd nd nd 0.05 J 0.17 J 0.15 0.10 J nd 0.01 J 0.58 nd nd nd 0.24 nd 0.26 nd 0.09J nd nd nd nd 0.16 J 0.28 nd 0.20 0.43 nd 0.26 J 0.21 0.04 J nd 0.02 J nd 0.37 0.49 3.70
nd nd nd 0.02 J nd nd nd nd 0.10 J 0.05 J 0.04 J 0.07 0.02 J 0.02 J 0.01 J 0.04 J nd 0.13 0.16 J 0.16 nd 0.12 0.34 0.08J 0.04 J nd nd 0.03 J 0.05 J 0.05 0.18 0.02 J 0.10 0.40 nd 0.46 0.29 1.20 0.13 0.02 J 0.25 0.57 7.31
nd nd 0.02J 0.06 J nd 0.08 nd 0.11 J 0.64 nd 0.31 0.26 nd 0.30 0.06 J nd 0.28 3.77 0.69 1.79 nd 1.27 0.78 0.75J 2.40 2.12 0.72 1.37 1.57 0.91 2.78 nd 1.76 0.90 0.26 2.25 nd nd 0.56 0.08 J 1.41 7.80 41.9
0.03 J nd 0.04J 0.05 J 0.04 J nd nd nd 0.20 0.25 0.10 J 0.09 0.08 J 0.04 J nd 0.07 J nd 1.55 0.40 0.49 nd 0.37 0.55 0.16J 0.31 1.29 nd 0.33 0.58 0.57 0.80 0.20 0.50 0.19 0.08 J 0.31 0.29 nd nd 0.14 J 0.63 2.81 13.5
nd nd nd 0.03 J nd nd nd nd nd 0.07 J 0.10 J nd 0.06 J 0.01 J nd 0.06 J nd nd nd nd 0.01 J 0.06 J 0.10 J 0.55J 0.56 0.15 J 0.08 J nd 0.16 J nd nd 0.01 J 0.07 J nd nd nd 0.03 J nd 0.18 0.03 J 0.17 J 0.07 J 4.16
J, Analyte concentration below corresponding Method Detection Limit (MDL); nd, not detected.
974
Volume 36/Number 12/December 1998 d e t e c t a b l e c o n c e n t r a t i o n s in s e d i m e n t s (1.38 ng/g). In general, high c o n c e n t r a t i o n s d e t e c t e d in s e d i m e n t s w e r e m a t c h e d by an i n c r e a s e d c o n c e n t r a t i o n in organisms an d vice versa. U n f o r t u n a t e l y , no live bivalves c ould be f o u n d in S a n t o D o m i n g o and P u e r t o Plata, locations with the highest c o n c e n t r a t i o n s o f trace o r g a n i c c o n t a m i n a n t s . It is p r e s u m e d that h a d bivalves b e e n f o u n d at t h e s e locations, c o n c e n t r a t i o n s in their tissues w o u l d have b e e n the g r e a t e s t m e a s u r e d in the D o m i n i c a n R ep u b lic .
Trace metals R es u l t s o f s e d i m e n t analyses are p r e s e n t e d in T a b l e 3. T h e data clearly show that for Cu, Hg, Pb an d Z n, highest c o n c e n t r a t i o n s are typically f o u n d in
s e d i m e n t s c o l l e c t e d n e a r the m o s t highly industrialized an d p o p u l a t e d cities (e.g. P u e r t o Plata and S a nt o D o m i n g o ) or at the m o u t h s of i m p o r t a n t river systems ( B a r a h o n a ) . M a x i m u m values for t h r e e o f the m e t a l s (Hg, Pb and Z n ) w e r e o b s e r v e d in s e d i m e n t s f r o m P u e r t o Plata which also c o n t a i n e d a high c o n c e n t r a t i o n of Cu. It should be noted, however, that this s a m p l e was c o l l e c t e d within the area o f the c o m m e r c i a l / r e c r e a tional p o r t o f P u e r t o Plata. In contrast, s e d i m e n t s far r e m o v e d f r o m industrial or riverine inputs, such as P e d e r n a l e s at the southwest en d o f the co unt r y and Isla S a o n a and S a b a n a de la M a r in the e a s t e r n sector, c o n t a i n e d relatively low c o n c e n t r a t i o n s o f all the metals analysed. C o n c e n t r a t i o n s of metals in oysters and clams f r o m various sites are given in T a b l e 4. As m e n t i o n e d ,
TABLE 2
Chlorinated hydrocarbon concentrations (ng/g, dry wt) in bivalve samples from the Dominican Republic. Location Station # Species Lipid weight (%) Hexachlorobenzene Alpha HCH Beta HCH Gamma HCH Delta HCH Heptchlor Heptachlor epoxide Oxychlordane Gamma chlordane Alpha chlordane
Trans-Nonachlor Cis-Nonachlor Aldrin Dieldrin Endrin Mirex 2,4' DDE 4,4' DDE 2,4' DDD 4,4' DDD 2,4' DDT 4,4' DDT PCB8/5 PCB18/I 7 PCB28 PCB52 PCB44 PCB66 PCB101/90 PCB118 PCB153/132 PCBI05 PCB138/160 PCB187 PCB128 PCB180 PCB195/208 PCB206 PCB209 Total HCHs Total chlordanes Total DDTs Total PCBs
Montecristi 1
Crassostrea rizophorae 2.93 0.37J nd nd nd nd nd nd nd nd 0.29 nd 0.22J 0.66J nd nd 0.30J 0.59 9.34 0.48 0.66 nd nd 3.93 2.20 0.09J 2.58 1.17 2.25 0.39 0.06J 0.47J nd 0.65J 0.17J nd nd 0.81 nd nd nd 0.51 11,1 32.3
Rio San Juan 3
Samana 5
Sanchez 6
Isognomon Crassotrea Crassotrea alatus rizophorae rizophorae 12.9 0.28 nd nd 0.39 0.77 nd nd 0.09J 0.07J 0.73 nd 1.09 1.73 nd 1.88 1.94 0.19 5.76 nd 0.51 nd 0.79 1.13 2.71 0.37 2.86 0.24J 0.29 0.21 0.42 1.26 nd 0.54 nd nd nd 1.93 nd nd 1.16 1.97 7.24 26.2
Sabana de la Mar 7
Crassotrea rizophorae
Miches 8
Isla Saona 9
Crassotrea Codakia rizophorae obicularis
San Pedro 10
Barahona 13
Tellina Isognomon fausta alatus
4.36
2.31
2.15
2.31
6.72
5.19
nd nd 0.18J nd 0.62 0.48 0.69 nd 2.22 2.17 1.10 0.82 1.47 0.93J nd nd 0.97 13.2 3.09 5.88 0.34 nd nd nd 4.41 3.47 1.56 4.86 2.43 1.25 2.42 0.35 1.67 0.37 0.12.I nd nd nd nd 0.80 7.47 23.4 51.2
0.29J nd nd nd nd nd nd nd 0.21J 0.59 0.17J nd nd nd nd nd 0.77 10.1 0.14J 0.93 nd 0.74 nd 2.45 nd nd 1.54 1.29 1.12 nd 0.55J nd 0.53J 0.09J nd 1.19 0.14J nd nd nd 0.96 12.7 19.5
0.32J nd 0.14J nd 0.09J nd nd nd 0.37J !.53 0.47 0.78 1.14 nd nd 1.50 0.68 11.8 0.47 1.89 nd 0.34J nd 1.26 nd 5.15 1.08 0.87 1.30 nd 1.28 nd 1.02 0.22J 0.51J 1.07 nd nd nd 0.23J 3.15 15.2 30.1
0.25J nd nd nd 0.13J nd nd 0.59 0.46 0.86 0.66 0.32J 2.42 10.4 0.43 nd 0.54 24.2 0.93 4.01 nd 0.56 2.32 1.15 nd nd 0.74 nd 1.30 nd 1.29 nd 0.88 nd 0.23J 2.37 nd nd nd 0.13J 2.91 30.2 22.5
0.15J nd nd nd nd nd nd nd nd 1/.56 nd 0.22 0.25J nd nd 0.64 nd 0.08J nd nd nd nd 3.34 nd nd nd 0.37 0.91 0.2[) nd nd nd 0.34 nd nd nd nd nd nd nd 0.79 0.08J 11.3
nd nd 0.81 nd 0.50 nd 0.42 nd 1.26 nd nd 0.47 1.47 nd nd 0.29 0.17 3.22 nd 1.39 0.10J nd 3.43 nd nd 0.46J 0.98 1.89 0.70 0.72 1.89 0,36 1.24 4.38 0.19J 7.27 3.57 1.24 0.57 1.30 2.15 4.87 61.9
16.2 nd nd nd 0.08J 0.57 nd 0.61 nd 0.24 1.04 0.46 0.65 1.39 0.36J nd 0.53 0.53 15.2 2.87 5.94 1.65 4.78 4.92 nd 1.26 1.15 0.88 2.56 2.05 3.74 6.16 1.89 4.04 0.58 1.64 5.54 nd nd nd 0.65 3.00 30.9 82.3
J, Analyte concentration below corresponding Method Detection Limit (MDL); nd, not detected. 975
Marine Pollution Bulletin TABLE 3
Trace metal concentrations (lag/g, dry wt) in sediment samples from the Dominican Republic. Location Puerto Plata Rio San Juan Samana Sanchez Sabana de la mar Miches Isla Saona San Pedro Santo Domingo Barahona Pedernales
Stn # 2 3 5 6 7 8 9 10 11 13 14
OC (%) CaCO3 (%) 2.4 9.5 0.82 0.75 0.68 1.8 11 3.7 4.1 5.5 4.0
79 76 54 73 78 26 37 3.2 74 79 79
A1
Cd*
18800 0.315, 0.435 3310 0.099, 0.150 0.277, 0.279 4900 0.120,0.181 0.038, 0.056 33000 0.147,0.149 623 0.049, 0.051 13100 0.028, 0.043 0.255, 0.273 0.186, 0.198 276 0.074, 0.091
Cr
Cu*
74.4 65.3 63.2 36.8 38.3 186 8.88 32.1 125
59.8,80.3 6.64,7.90 19.3 17.5,29.4 19.6 102, 111 4.04, 4.82 17.9,25.5 103 31.8, 34.6 1.01,1.63
10.3
Fe
Hg*
Ni
24500 0.392, 0.433 4640 0.140, 0.154 0.186, 0.368 34700 0.122, 0.230 0.151, 0.156 48700 I).186,0.282 603 0.099, 0.133 16500 0.128, 0.212 0.407, 0.565 0.122, 0.401 230 0.096, 0.098
Pb*
Zn*
67.7 81.8, 134 30.8 6.66,9.79 16.6, 17.2 50.0 4.44,8.64 3.63, 4.73 124 9.20, 14.9 4.38 2.57, 5.24 16.8 4.73,5.59 37.2, 57.4 36.8, 38.6 1.71 0.42, 2.69
202, 244 13.(I,19.7 56.9 52.0, 56.2 42.9 91.6,98.6 4.52, 7.76 37.1, 40.8 184 85.7, 99.4 2.34, 3.91
*Two separate analyses are shown. bivalves were not available at all stations where sediments were collected; therefore, comparisons with sediment data can only be m a d e at certain sites, and then only a m o n g the same species of bivalves. T h e oysters (Crasssostrea rizophorae) f r o m stations in Bahia S a m a n a showed no consistent trends in c o n t a m i n a n t levels. L e a d and Z n levels were highest in oysters from S a m a n a whereas maximum levels of Cu, Ni and Cr were found in samples from Sanchez. Concentrations in a n o t h e r species of oyster (Isognomon alatus, flat tree-oyster) collected at B a r a h o n a and Rio San Juan did not suggest contamination except perhaps for the somewhat e n h a n c e d levels o f Pb, Ni and Cu at B a r a h o n a where similarly elevated concentrations of predominantly a n t h r o p o g e n i c Cu, Pb and Zn were m e a s u r e d in sediments. While c o m p a r i n g metal concentrations in both species of oysters, it is interesting to note the marked differences in A1, Cd and Cu levels. Concentrations of these metals were a factor of 10-100 times lower in the fiat tree-oyster. A l t h o u g h these oysters were collected from different locations along the Dominican Republic coastline and, therefore, might be exposed to different environmental levels of trace metals which could explain this dissimilarity, no significant differences are observed in the concentrations of the remaining reported metals~ including Hg. T h e different ability to concentrate organic and inorganic chemicals by different bivalves has been discussed by O ' C o n n o r et al. (1994).
Mercury in bivalves and sediments from the Bahia S a m a n a area are of particular interest since there are reports that some 270 years ago two Spanish vessels carrying 400 tonnes of pure mercury sank off Cabo San Rafael near Miches in approximately 1 3 m depth (Peterson, 1979). A t t e m p t s to excavate the ship for treasure using subsediment air hoses were carried out in 1978 and, in fact, vivid descriptions of the liquid mercury f o u n d in the sediments at the time of the excavation have been reported (Peterson, 1979). W a t e r circulation into Bahia S a m a n a from the wreck area is along the n o r t h e r n coast and out through the middle section of the bay. W a t e r discharged into the inner portion of the bay by the Y u n a River is transported seaward along the west and southern coasts of Bahia Samana. It is therefore noteworthy that, despite such a t r e m e n d o u s input source of Hg in this region, none of the sediments from nearby stations in the Bahia Samana, particularly Samana, Sabana de la Mar and Sanchez, contained elevated concentrations of Hg. This could reflect net burial and isolation of the source by continual resuspension and sedimentation events; however, verification of this hypothesis requires a much m o r e t h o r o u g h study of the bay area including sediment cores to establish temporal and spatial trends. Nevertheless, the very high concentration of Hg (7.02 lag/g dry wt) detected in oysters from Sabana de la Mar does suggest a significant source of anthropogenic contamination in this area. Likewise, Hg was
TABLE 4
Trace metal concentrations (lag/g, dry wt) in bivalve samples from the Dominican Republic. Location
Stn #
Montecristi Samana Sanchez Sabana de la Mar Miches Rio San Juan Barahona
1 5 6 7 8 3 13
Isla Saona San Pedro
9 10
976
Species Oysters Crassotrearizophorae Crassotrearizophorae Crassotrearizophorae Crassotrearizophorae Crassotrearizophorae lsognomon alatus Isognomon alatus Clams Codakiaorbicularis Linn6 Tellinafausta
AI
Cd
Cr
650 316 2240 319 287 59.5 26.0
0.35 1.15 1.74 2.57 1.87 0.26 0.24
4.83 2.88 10.7 1.73 1.92 4.96 2.38
162 201 866 301 112 7.58 19.7
0.30 0.04
1.66 4.15
3.08 14.1
3.80 996
Cu
Fe
Hg
Ni
Pb
Zn
750 495 3400 415 369 277 253
0.49 0.55 7.02 1.38 0.98 0.59
1.74 2.15 7.92 1.73 1.34 1.25 2.90
0.57 1.46 0.81 0.08 0.09 0.25 1.44
1500 4380 2030 2570 1050 4000 4010
50.9 1080
0.29 0.75
1.57 4.91
0.73 0.30
22.9 51.4
Volume 36/Number 12/December 1998
high in oysters from nearby Miches (Table 4). Sediments from these two stations did not show the same degree of Hg enhancement (Table 3), hence, it is difficult to discern the origin of the high Hg levels measured in these bivalves. It may be that low level, chronic Hg inputs from local sources rather than any residual Hg from the nearby shipwreck site are responsible for the observed contamination. Furthermore, it is of interest that Hg levels in bivalves (mean = 0.61, range 0.29-0.98 lag/g dry wt) from six other stations around the island are, on average, relatively high when compared with concentrations in similar species from other areas (e.g. NOAA, 1987; Claisse, 1989). For example, Hg concentration in oysters averaged 0.21 +0.09 lag/g dry weight in 1869 samples collected from the French Atlantic and Mediterranean coasts between 1979 and 1993 (RNO, 1995). Based on our preliminary findings with bivalves, we suggest that a more detailed study of Hg, particularly around Bahia Samana, is warranted.
Data comparison Total selected chlorinated hydrocarbon and trace metal concentrations in bivalve samples and nearshore sediments reported for different Caribbean and tropical west Atlantic locations are listed in Table 5 and Table 6. Although comparisons of data among different studies are generally complicated because the methods used in each are rarely standardized, it is worthwhile looking at some of the published data to put the contamination problems in the Dominican Republic into perspective. In general, information on the levels of these organic compounds and metals in the area is scarce. A comparison of the chlorinated hydrocarbon concentrations measured in the
Dominican Republic with recently reported levels in samples from the Caribbean area shows that these concentrations compare well with the published findings. For example the ranges of concentrations for total chlordanes, DDTs and PCBs reported in bivalves from Puerto Rico, collected between 1991 and 1994 as part of the NOAA's National Status and Trends Program, are comparable with the ranges determined during this study (Table 5). Possible exceptions are the high total DDT concentrations encountered in bivalves samples from Barahona (30.9 rig/g), Miches (30.2 ng/g) and Samana (23.4 ng/g). Similar high concentrations were encountered in oyster samples collected near Port Royal, Jamaica (24.0ng/g) during the International Mussel Watch - - Phase I (Sericano, unpublished results). Except for the relatively high total DDT concentrations in sediments from Puerto Plata (12.5 ng/g) and Santo Domingo (7.80 rig/g), the levels of these pesticides in the Dominican Republic and Puerto Rico are comparable. A similar situation is observed for PCBs; concentrations encountered in sediments from Puerto Plata (25.3 ng/g) and Santo Domingo (41.9 ng/g) are outside the range of concentrations measured in sediments from Puerto Rico. Trace metal concentrations in sediments from the most contaminated areas in the Dominican Republic were not exceptional when compared with those reported for other coastal areas throughout the world (Fowler, 1990). For the Caribbean region, much lower concentrations of Cu and Fe have been reported in sediment samples from nearshore locations in Tobago (Rajkumar and Persad, 1994); however, significantly higher concentrations of mercury, lead and zinc were found in sediments collected around a Havana sewage outfall (Gonzalez and Torres, 1990). Nevertheless, the trace metal levels reported here are similar to, or in
TABLE 5 Mean and range of chlorinated hydrocarbon concentrations (ng/g, dry wt) in nearshore surface sediments and bivalve samples from the Caribbean and tropical West Atlantic areas.
Location
Year
Total Chlordanes
Total DDTs
Total PCBs
1995
0.51 _ 0.55 (
2.88 + 3.89 (0.21-12.5) 0.91 +0.32 (0.36-1.52) ( < MDL- 17.7)
9.73 _+12.9 (0.46-41.9) 10.5 -+5.4 (5.03-22.7)
15.1 -+ 11.0 ( < MDL-30.9) 5.03 -+3.41 (2.08-10.2) 1.40 -+0.61 (1.00-2.10) 4.67 -+2.72 (3.00-7.80) 2.47 14.7 -+ 13.1 (5.44-24.0) 2.27 _+2.54 (0.47-4.06)
37.5 -+ 23.0 (11.3-82.3) 31.9 -+ 14.2 (18.3-55.1) 24.5 -+ 17.8 (3.80-36.1) 58.5 -+25.4 (32.3-83.0) 15.3 20.2 __+7.43 (14.9-25.4) 12. l + 4.96 (8.54-15.6)
Reference
Sediments
Dominican Republic Puerto Rico Mexico
1991/1992 1992
This study GERG, 1993 Gold-Bouchot et al., 1993
Bivalves
Dominican Republic Puerto Rico
1995 1991/1992 1992/1993 1993/1994
Cuba Jamaica
1992 1992
Trinidad and Tobago
1992
2.55 -+2.10 (0.51-7.47) 0.39 __+0.56 (0.79-3.79) < MDL 1.20 -+0.78 (0.70-2.10) 4.08 4.64 +__4.59 (1.39-7.88) 1.72 ± 0.94 (1.05-2.38)
This study GERG, 1993 GERG, 1994 GERG, 1995 IMW Program, Sericano unpublished results IMW Program, Sericano unpublished results IMW Program, Sericano unpublished results
977
Marine Pollution Bulletin TABLE 6 M e a n + S D and range (in parentheses) of heavy metal concentrations (lag/g, dry wt) in nearshore surface sediments and bivalves from the Caribbean and tropical West Atlantic areas Location
AI
Cd
Cr
Cu
Fe
Sediments Dominican Republic Guadaloupe Trinidad Tobago
Hg
10600_+ 12000 0.159_+0.109 64.0_+54.8 37.3_+38,1 18600_+18500 0.230_+0.123 (276-33000) (0.028-0,435) (8.88-186) (1.01-111) (230-48700) (0.096-0.565) (9.3-187) (2,4-68) 0.626_+0.350 2,89_+2.53 2380_+1960 10,040-2.12) (0.06-16,0) (12.4-15700) (4-297) (0,01-7.2) Cuba Cuba (<63 lam) 8800 96 240 24 80(I 17.3 (4400-20000) (22-339) (18-716)(8300-57600) (0,64-76) (63-150 ~tm) 6000 73 172 17 900 7.9 (2300-15 800) (22-225) (24-567) (0.48-32) Bermuda (1-86) Brazil (21-28) (0.050-/I.150) (4.9-75) Mexico Bivalves Dominican Republic Venezuela
544_+712 0.947_+0.917 3.91 _+2.86 187+275 788+1030 (3.80-2240) (0.04-2.57) (1.66-10.7) (3.08-866) (50.9-3400) 0.61_+0.19 0.82_+0.26 27.0_+10.4 10.33-0.91) (0.46-1.2) 114.0-49.1) Mexico (Gulf coast) 4.2_+ 1.8 324_+ 115 958_+546 ( 1.2-7.8) ( 161-662) 1170-2650) 3.25_+1.43 0.42_+0.19 97.0_+47.7 USA (SE coast) (SE coast) (1.4-10.5) (0.11-0.88) (50-337) (Gulf coast) 4.09_+1.64 0.66_+0.34 126_+63.2 (0.96-8.83) 10.13-1.30) 19.66-417)
some cases lower than, concentrations in sediments from other Caribbean or tropical Atlantic sites (Table 6). Although a similar scenario can be observed when comparing bivalve data, comparative data are much scarcer (Table 6). Concentrations measured in samples from the Dominican Republic are, with some exceptions, comparable with previous reports in samples from Mexico and Venezuela. On the one hand, chromium concentrations reported here appear to be elevated when compared with bivalves from the Morrocoy National Park in Venezuela (Jaffe et al., in press). On the other hand, significantly higher concentrations of other metals, particularly Pb and Cd, have been measured in oysters from a tropical Mexican lagoon (Vazquez et al., 1993). In general, the bivalve data do not suggest any major source of heavy metal contamination in Dominican Republic except for Hg in the vicinity of Bahia Samana. Conclusions The analysis of selected trace organic contaminants and trace metals in bivalve and sediment samples from coastal areas of the Dominican Republic allowed us to define the geographical distributions of these contaminants and identify some areas with high concentrations. DDT and its metabolites, DDD and DDE, were the most abundant chlorinated pesticide detected in the samples analysed. PCB concentrations were generally higher than concentrations detected for chlorinated pesticides and the highest concentrations were detected near large industrialized areas and ports. A similar correlation was observed for predominantly anthropo978
Ni
Pb
Zn
42.2_+43.3 22.9_+31.9 86.2_+79.1 (1.71-124) (0.420-134) (1.96-277) (1.7-236) 119-664) (2.4-30.5) 4.01 _+2.04 8.87_+9.74 (0.30-20.9) (0.10-39.3) (8-340) (8-646) 46 280 794 (11-112) (44-903) (72-3740) 35 229 644 (3.5-94) (50-967) (68-3220) (3-157) (15-178) (43-88) 1102-151) (17-91)
(21-130)
Reference This study Bernard, 1995 Hall and Chang-Yen, 1986 Rajkumar and Persad, 1994 Gonzalez and Brugmann, 1991 Gonzalez and Torres, 1990 Gonzalez and Torres, 1990 Burns et al., 1990 Knoppers et al., 1990 Lacerda et al., 1993 Paez Osauna et al., 1986
1.51 _.+2.25 2.83_+2.20 0.637_+0.529 2180_+1680 This study (0.290-7.02) (1.25-7.92) 10.08-1.46) (22.9-4380) 15.2_+2.25 0.560_+0.09 910_+580 Jaffe et al., in press (10.6-17.8) (0.40-0.71) (250-2050) 8.84_+4.68 620_+268 Vazquez et al., 1993 (2.9-24.2) (200-1320) 0.07_+0.04 2.38_+1.14 0.32_+0.11 2750_+1100 NOAA, 1987 10.01-0.13) (0.6-6.56) 10.11-0.93) (1000-5500) 0.13_+0.10 2.18_+0.91 0.57_+0.30 1910_+1060 NOAA, 1987 (0.02-0.40) 10.55-12.56) (0.09-2.33) (73-8000)
genic metals (Cu, Hg, Pd and Zn). A comparison of contaminant concentrations observed during this study with those reported for similar environments in the Caribbean and west Atlantic coastal areas indicates that levels of most of these analytes in the coastal marine environment of the Dominican Republic are similar to or in some cases lower than the concentrations reported in those studies. However, in the case of Hg, it is noteworthy that relatively high concentrations were found in bivalves living in the vicinity of a known major source of Hg contamination in Bahia Samana. A thorough study of this area to delineate the extent of potential Hg contamination from that source is recommended. This work was supported in part by IAEA Technical Cooperation Project DOM/7/002. The authors wish to thank Ms S. Azemard, Ms A. Dean, Ms N. Eaker and Ms R. Stevenson for assistance with the metal analyses and Ms D. Frank for assistance with the chlorinated hydrocarbon analyses. The IAEA Marine Environment Laboratory operates under an agreement between the International Atomic Energy Agency and the Government of the Principality of Monaco. Bernard, D. (1995) Metals in sediments from two lagoons off Guadaloupe West Indies. Marine Pollution Bulletin 30, 619-621. Bloom, N. S. (1992) On the chemical form of mercury in edible fish and marine invertebrate tissue. Can. J. Fish. Aquat. Sci. 49, 1010-1017. Bloom, N. S. and Crecelius, E. A. (1987) Distribution of silver, mercury, lead, copper and cadmium in central Puget Sound sediments. Mar. Chem. 21, 377-390. Burns, K. A., Ehrhardt, M. G., Pherson, J. M., Tierny, J. A., Kananen, G. and Connelly, D. (1990) Organic and trace metal contaminants in sediments, sewater and organisms from two Bermudan harbours. J. Exper. Mar. Biol. Ecol. 138, 9-34.
Volume 36/Number 12/December 1998 Claisse, D. (1989) Chemical contamination of French coasts. The results of a ten years Mussel Watch. Marine Pollution Bulletin 20, 523-528. Fowler, S. (1990) Critical review of selected heavy metal and chlorinated hydrocarbon concentrations in the marine environment. Mar. Environ. Res. 29, 1-64. Fowler, S. W., Readman, J. W., Oregioni, B., Villeneuve, J.-P. and McKay, K. (1993) Petroleum hydrocarbons and trace metals in nearshore Gulf sediments and biota before and after the 1991 war. Marine Pollution Bulletin 27, 171-182. GERG (1993) NOAA's National Status and Trends, Mussel Watch Project, Analytical Data Year VII, Geochemical and Environmental Research Group, Texas A&M University, College Station, Texas, USA. GERG (1994) NOAA's National Status and Trends, Mussel Watch Project, Analytical Data Year VIII, Geochemical and Environmental Research Group, Texas A&M University, College Station, Texas, USA. GERG (1995) NOAA's National Status and Trends, Mussel Watch Project, Analytical Data Year IX, Geochemical and Environmental Research Group, Texas A&M University, College Station, Texas, USA. Gold-Bouchot, G., Silva-Herrera, T. and Zapata-Perez, O. (1993) Chlorinated pesticides in the Rio Palizada Campeche, Mexico. Marine Pollution Bulletin 26, 648-650. Gonzalez, H. and Torres, I. (1990) Heavy metals in sediments around a sewage outfall at Havana, Cuba. Marine Pollution Bulletin 21, 253-255. Gonzalez, H. and Brugmann, L. (1991) Heavy metals in littoral deposits off Havana city, Cuba. Chemistry and Ecology 5, 171-179. Hall, L. and Chang-Yen, I. (1986) Metals in sediments off Trinidad, West Indies. Marine Pollution Bulletin 17, 274-276. Jaffe, R., Leal, I., Alvarado, J., Gardinali, P. R. and Sericano, J. L. Baseline study on the levels of organic pollutants and heavy metals in bivalves from the Morrocoy National Park, Venezuela. Marine Pollution Bulletin (in press). Knoppers, B. A., Lacerda, L. D. and Patchineelam, S. R. (1990) Nutrients, heavy metals and organic micropollutants in an eutrophic Brazilian lagoon. Marine Pollution Bulletin 21, 381-384. Lacerda, L. D., Carvalho, C. E. V., Rezende, C. E. and Pfeiffer, W. C. (1993) Mercury in sediments from the Paraibo do sul river continental shelf S.E. Brazil. Marine Pollution Bulletin 26, 220-222. Liang, L. and Bloom, N. S. (1993) Determination of total mercury by single stage gold amalgamation with cold vapour atomic fluorescence spectrophotometry. J. Analyt. Atom. Spec. g, 591-594.
Loring, D. and Rantala, R. (1992) Manual for the geochemical analysis of marine sediments and suspended particulate matter. Earth-Science Reviews 32, 235-293. NOAA (1987) National Status and Trends Program for Marine Environmental Quality. Progress Report. A summary of selected data on chemical contaminants in tissues collected during 1984, 1985 and 1986. NOAA Tech. Memo., Rockville, Md., NOS OMA 38, 23 pp. O'Connor, T. P., Cantillo, A. Y. and Lauenstein, G. G. (1994) Monitoring of temporal trends in chemical contamination by the NOAA National Status and Trends Mussel Watch Project. In Biomonitoring of Coastal Waters and Estuaries (K. J. M. Kramer, ed.), pp. 29-50. CRC Press Inc., Boca Raton, FL. Paez Osauna, F., Botello, A. V. and Villanueva, S. (1986) Heavy metals in Coatzcoalcos estuary and Ostion lagoon, Mexico. Marine Pollution Bulletin 17, 516-519. Peterson, M. (1979) Graveyard of the quicksilver galleons. National Geographic December, 850-876. Rajkumar, W. and Persad, D. (1994) Heavy metals and petroleum hydrocarbons in nearshore areas of Tobago, West Indies. Marine Pollution Bulletin 28, 701-703. RNO (1995) Surveillance du milieu marin. Travaux de RNO. Edition 1995. Institut Fran~cais de Recherche pour l'Exploitation de la Mer, France, 32 p. Sericano, J. L. (1993). The American oyster (Crassostrea virginica) as a bioindicator of trace organic contamination. Ph.D. Dissertation, Texas A&M University, 242 p. Sericano, J. L., Atlas, E. L., Wade, T. L. and Brooks, J. M. (1990) NOAA's Status and Trends Mussel Watch Program: chlorinated pesticides and PCBs in oysters (Crassostrea virginica) and sediments from the Gulf of Mexico, 1986-1987. Mar. Environ. Re.s'. 29, 161-203. Sericano, J. L., Wade, T. L. and Brooks, J. M. (1996) Accumulation and depuration of organic contaminants by the American oyster ( Crassostrea virginica ). Sci. Total Environ. 179, 149-160. UNEP (1984) Sampling of selected marine organisms and sample preparation for trace metal analysis. Reference Methods for Marine Pollution Studies No. 7 Rev. 2, UNEP, Geneva. UNEP/IOC/IAEA (1995) Manual for the Geochemical Analysis of Marine Sediments and Suspended Particulate Matter. Reference Methods for Marine Pollution Studies No. 63, 74 pp., UNEP. Nairobi. Vazquez, G. F., Sanchez, G. M. and Virender, K. S. (1993) Trace metals in the oyster Crassostrea virginica of the Terminos Lagoon, Campeche, Mexico. Marine Pollution Bulletin 26, 398-399.
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Marine Pollution BuUetm. Vol. 36, No, 12, pp. 971-979, 1998 © 1998 Elsevier Science Ltd. All rights reserved Printed in Great Britain (~)25-326X/98/$19.1~1+0,0()
Levels of Chlorinated Hydrocarbons and Trace Metals in Bivalves and Nearshore Sediments from the Dominican Republic L U C I A N O SBRIZ*, M A R G A R I T A R. A Q U I N O ? , NAT1VIDAD M. A L B E R T O DE R O D R I G U E Z ~ , S C O T T W. F O W L E R § and JOSE L. SERICANO¶II
*Comisi6n Nacional de Asuntos Nucleares (CONAN), Calle Coronel Fernandez Dominguez 30-A, Apartado Postal 30333, Ens. La Fe, Santo Domingo, D.N., Rep(lblica Dominicana tDepartamento de Quimica, Universidad Nacional Pedro Henriquez Urena, Santo Domingo, D.N., Rep(tblica Dominicana ~Instituto de Fisica, Universidad Aut6noma de Santo Domingo, Santo Domingo, D.N., Rep~blica Dominicana §IAEA Marine Environment Laboratory, 19 av. des Castelans, B.P. 800, MC-98012, Monaco Cedex Monaco ¶Geochemical and Environmental Research Group, TexasA&M University, 833 Graham Rd, College Station, TX 77845, USA Bivalves (Crassostrea rizhophorae, Isognomon alatus, Codakia orbicularis Linn~, and Tellina fausta) and sediment samples collected from 12 locations along the Dominican Republic coastline were used to assess the degree of nearshore contamination by selected chlorinated hydrocarbons and heavy metals. Concentrations of total chlordanes, DDTs and PCBs ranged from 0.51 to 7.47 ng/g, < MDL to 30.9 ng/g and 11.3 to 82.3 ng/g, and from < M D L to 1.73 ng/g, 0.21 to 12.5 ng/g and 0.46 to 41.9 ng/g in bivalves and surface sediments, respectively. The concentration ranges of predominantly anthropogenic Cu, Pb and Zn were 3.08866 llg/g, 0.08-1.46 llg/g and 22.9-4380 I~g/g in bivalve soft parts and 1.01-111mg/g, 0.420-1341~g/g and 1.96-277 l~g/g in surface sediments, respectively. Mercury concentrations ranged from 0.290 to 7.02 lag/g and from 0.096 to 0.565 l~g/g in both matrices. The relatively high Hg concentrations found in bivalves from two stations in Bahia Samana, near to a known source of past Hg contamination in the sediments, require a more in-depth survey of the area. In general the concentrations of selected chlorinated hydrocarbons and trace metals, compared with those reported for the same matrices in the Caribbean and west Atlantic coastal areas, show at present the existence of only very localized contamination problems in the Dominican Republic. © 1998 Elsevier Science Ltd. All rights reserved
worldwide. The Dominican Republic is not an exception in this context. Marine contamination is becoming a national issue in this Caribbean country as a result of growing industrial and agricultural activities. The rapid, and somewhat uncontrolled, growth of these activities in the Dominican Republic makes it necessary to have an adequate action plan to protect the environment, particularly the nearshore coastal zone. Besides the need to keep the fauna free of contaminants for local human consumption, the warm and clear tropical waters surrounding the Dominican Republic are of vital importance for the island and its policy to promote and encourage tourism. Even though the contaminant inputs into the environment through industrial and agricultural activities are well known in the Dominican Republic, a monitoring programme has not yet been established to evaluate the present status of contamination. Such an effort is important to derive baseline levels to evaluate future trends in the concentration of different contaminants and their potential impact on the coastal environment. The main objective of this project was to establish a local environmental monitoring network which uses sediments and bioindicator species to assess trends of selected chlorinated hydrocarbons (e.g. pesticides and PCBs) and heavy metal contaminants in coastal areas of the Dominican Republic.
The contamination of the coastal marine environment is a problem of concern for scientists and politicians
Sampling and Sample Preparation
]lAuthor for c o r r s p o n d e n c e .
For the initial survey, 14 locations around the island were selected for sampling (Fig. 1). In general, access to the coastal sampling sites was by road; however, in 971
Marine Pollution Bulletin
instances where a vessel was required to reach the site, a boat was provided by the Comisi6n Nacional de Asuntos Nucleares (CONAN). Although an attempt was made to obtain samples from every preselected site, this was not always possible. Fine-grained sediments were not found in Bahia de Ocoa, Montecristi and Nagua. Furthermore, bivalves were not found in Pedernales, Bahia de Ocoa, Santo Domingo, Puerto Plata and Nagua. In general, the sampling strategy followed that used for the NOAA's National Status and Trends Program in the US (Sericano et al., 1990). Bivalves (n = 20) and sediment samples were collected over a 2-week period in August 1995 from 9 and 11 sites, respectively, and analysed for a selected suite of chlorinated pesticides, polychlorinated biphenyls (PCBs) and trace metals. The sampling locations were selected to provide a broad coverage of Dominican Republic coastline including potential point sources of contamination. The general sampling criteria included the collection of sediments and organisms beyond the zone of initial dilution of wastes or suspected point-source discharges of contaminants. Sediment samples were collected mainly in areas containing fine-grained sediments. In most cases, sampling of bivalves was limited to natural substrates (e.g. rocks, roots of mangroves or mud) to avoid any inadvertant contamination. In a few 72 °
,o°1
instances, however, bivalves were only found attached to artificial structures (e.g. pilings). In these cases, samples were collected and the type of artificial structure recorded for future reference. Sediment samples for trace metals were either collected by hand, with the use of a clean plastic spoon, or using a box corer. Subsamples from the centre of the box corer were taken with the use of a clean plastic spoon. Sediment samples for organic contaminants were collected with the use of a solvent-rinsed metal spoon. Bivalves were collected by hand in intertidal or shallow subtidal areas. Bivalve samples were processed in the laboratory in Santo Domingo, usually within 24 h of collection, by shucking them using a precleaned plastic knife for metals, and an oyster knife for trace organics. Sediment and bivalve samples destined for trace-metal analysis were placed in plastic Ziploc bags while samples for trace-organic analysis were placed in precombusted glass jars with Teflon-lined caps.
Analytical Methods Chlorinated hydrocarbons The analytical procedure used in the extraction, fractionation and clean-up of chlorinated pesticides and PCBs in bivalves and sediment samples has been described elsewhere (Sericano et al., 1990). Briefly,
710
I
700
690
l
I
l
i
N
A J S
~7
HAITI
4
f,¢
J
19 ° .
% !
12
,
~-
I%
18"
~14
SAMPLING 1 2 3 4 5 6 7
11
10
LOCATIONS
Montecristi (O) Puerto Plat,, (S) Rio San Juan (S/O) Nagua Samana (S/O) Sanchez(S/O) Sabana de la Mar iS/O) S = sediments
8 9 10 11 12 13 14
Miches(S/O) Isla Saona (S/O) San Pedro (S/O) S~mtoDomingo(S) Bahiade Ocoa Barahona (S/O) Pedernales[SI 0 = organisms
DOMINICAN REPUBLIC I •
2,0
• 0
e e 20
Fig. 1 Sediment and bivalve sampling locations in the Dominican Republic.
972
40 a 40
60 MI 60 KM
Volume 36/Number 12/December 1998 approximately 15g of wet tissue and 20g of wet sediment were extracted, after the addition of anhydrous NazSO4, with methylene chloride using a homogenizer and Soxhlet apparatus, respectively. Before extraction, 4,4' dibromooctafluorobiphenyl (DBOFB), PCB 103 and PCB 198 were added to all samples, blanks and reference material as internal standards. Each set of 8-10 samples was accompanied by a complete system blank, spiked blank and reference material that were carried through the entire analytical method as part of the laboratory quality assurance/quality control (QA/QC) procedure. Tissue and sediment extracts were fractionated by partially deactivated silica:alumina column chromatography. The sample extracts were eluted from the column using a 1:1 mixture of pentane and methylene chloride. The tissue fraction was further purified by high-performance liquid chromatography to remove lipids. The sample extracts were finally concentrated to a volume of 1 ml in hexane for gas chromatographic analysis. Chlorinated pesticides and polychlorinated biphenyls were analysed by gas chromatography using an electron capture detector (ECD) and a 30-m narrow bore, fused-silica column with DB-5 as the bonded phase. The column temperature was programmed at 100°C for 1 min, increasing at 5°Cmin -1 to 140°C, held for 1 min, increasing at 1.5°C min -I to 250°C, held for 1 min, and increasing at 10°C min -1 to 300°C with a final hold of 5 min. The injector and detector temperatures were set at 275 and 325°C, respectively. Helium and a mixture of argon:methane (95:5%) were used as the carrier and make-up gases, respectively. The instrument was calibrated by injection of the standard component mixtures at four different concentrations prior to the analysis of the samples.
Trace metals Atomic absorption spectrophotometry by flame or graphite furnace was used to analyse all metals except Hg. Mercury was analysed by cold vapour atomic absorption spectrometry. Specific details of the methods used for trace-metal analyses have been reported elsewhere for bivalves (UNEP, 1984; Bloom, 1992; Fowler et al., 1993) and sediments (Bloom and Crecelius, 1987; Liang and Bloom, 1993, UNEP/IAEA/ IOC, 1995). Briefly, subsamples of bivalve soft parts were lyophilized, ground to a fine powder, and homogenized. The homogenized tissues were then dissolved in concentrated nitric acid. Sediment samples were lyophilized and fractions <63 gm separated by nylon sieves. For sediment sample digestion - 0.1-0.3 g of the < 63-gm fractions were microwaved in closed Teflon bombs with hydrofluoric acid (HF) in combination with aqua regia. The use of HF is essential since it is the only acid that completely dissolves the silicate lattices and releases all metals. Total mercury was analysed by digesting the sediment samples (0.2-0.3 g) with a mixture of concentrated
nitric acid and sulfuric acid at room temperature for up to 12 h (cold digestion) followed by digestion at 100°C for 3 h. Mercury present in the samples was first reduced to its elemental state with sodium borohydride, and the mercury vapour was then passed through a quartz absorption cell of an atomic absorption spectrometer where its concentration was measured and recorded. Reagent blanks and standard reference materials (SRMs) were prepared and digested for each batch of samples as part of the laboratory internal QA/QC procedures.
Ancillary parameters The organic carbon content (OC%) of the sediment samples was determined by wet oxidation with potassium dichromate and concentrated sulfuric acid followed by titration with ammonium sulfate. Calcium carbonate content (CaCO3%) in the sediments was determined by gravimetry after treatment of the samples with excess hydrochloric acid (e.g. Loring and Rantala, 1992; UNEP/IAEA/IOC, 1995).
Results and Discussion Chlorinated hydrocarbons The concentrations of a selected suite of chlorinated pesticides and PCBs measured in sediments and bivalve samples are listed in Table 1 and Table 2, respectively. Concentrations of individual chlorinated pesticides in sediments ranged from less than the corresponding Method Detection Limit (MDL) to 6.04ng/g. The most abundant chlorinated pesticide residues encountered in these samples were DDT and its metabolites, DDE and DDD. Concentrations of total DDT (i.e. sum of o - p ' and p-p' isomers of DDT, DDE and DDD) ranged from < MDL at a site located near the border between the Dominican Republic and Haiti (Pedernales) to 12.5ng/g in Puerto Plata. A concentration of 7.80 ng/g was measured in the vicinity of the capital city Santo Domingo. Similarly, the highest total chlordane concentrations were encountered near these two cities (1.71 and 1.41 ng/g, respectively). Other chlorinated pesticides occasionally encountered in sediments were dieldrin and mirex. Most of the pesticide analytes in sediment samples, however, were undetected. Concentrations of PCBs, expressed as the sum of individual congeners, were generally higher than levels observed for pesticides and ranged from 0.46 to 41.9 ng/g. The highest concentrations were measured in sediments collected from heavily inhabited locations or areas with significant port and/or industrial activities, e.g. Santo Domingo (41.9 ng/g) and Puerto Plata (25.3 ng/g). The same suite of chlorinated pesticides and PCBs was also determined in bivalves. The concentration of total DDTs in total soft tissue ranged from < M D L in samples from Isla Saona, on the extreme eastern shore of the Dominican Republic, to 30.9 ng/g in Barahona 973
Marine Pollution Bulletin
located on the southern coast of the island. A similar high concentration was encountered in bivalves from Miches (30.2 ng/g). The average contribution of DDTs, DDDs and DDEs to the total DDT load observed at those sites where both sample types were collected were different in bivalves (5.0, 17.0 and 78.0%, respectively) compared with sediments (20.4, 35.1 and 44.5%, respectively). Total chlordane concentration was highest in the bivalves collected near Samana (7.47 ng/g). Other chlorinated pesticides occasionally encountered in bivalve samples were dieldrin, aldrin, endrin, hexachlorocyclohexane isomers and mirex. Concentrations of PCBs were generally higher in bivalves collected near large industrialized areas and/or ports (e.g. Barahona, Puerto San Pedro and Samana) and lower in samples collected from more remote areas (e.g. Isla Saona). PCB congeners are also distri-
buted differently in bivalves compared with sediments. In general, bivalves preferentially accumulate congeners with four, five and six chlorine atoms. This preferential uptake by bivalves has been extensively discussed elsewhere (e.g., Sericano, 1993; Sericano et al., 1996). As expected, bivalves were found to accumulate chlorinated pesticides and PCBs to concentrations significantly higher than those in sediment from the same sampling location. For example, the average ratios of total DDT, PCB and chlordane concentrations in bivalve tissues to sediment samples from the same location were 20 (2-70), 7 (1-10) and 15 (2-45), respectively. The general geographic distribution of concentrations along the coast, however, corresponded well. Dieldrin, for example, was only detected in significant amounts in one oyster sample collected near Miches (10.4 ng/g) which corresponded to the highest
TABLE 1
Chlorinated hydrocarbon concentrations (n~g, dry wt) in sediment samples from the Dominican Republic.
Location Station #
Puerto Plata 2
Rio San Juan 3
Samana 5
Sanchez 6
Sabana de la Mar 7
Miches 8
Isla Saona 9
San Pedro 10
Santo Domingo 11
Barahona 13
Pedernales 14
Hexachloronbenzene Alpha H C H Beta H C H Gamma HCH Delta H C H Heptachlor Heptachlor epoxide Oxychlordane G a m m a chlordane Alpha chlordane Trans-Nonachlor Cis-Nonachlor Aldrin Dieldrin Endrin Mirex 2,4' D D E 4,4' D D E 2,4' D D D 4,4' D D D 2,4' D D T 4,4' D D T PCB8/5 PCB18/17 PCB28 PCB52 PCB44 PCB66 PCB101/90 PCB118 PCB153/132 PCB105 PCBI38/160 PCBI87 PCB128 PCB180 PCB195/208 PCB206 PCB209 Total H C H s Total chlordanes Total D D T s Total PCBs
0.03 J nd nd 0.06 J nd nd nd 0.15 1.05 nd 0.23 0.30 nd 0.13 nd 0.19 0.21 6.04 1.80 3.70 nd 0.74 0.41 nd 1.60 1.62 0.68 1.23 1.60 0.90 1.07 0.27 0.86 nd 0.58 nd nd nd 0.76 0.06 J 1.73 12.5 25.3
0.03 J nd nd nd nd nd nd nd 0.07 J 0.06 J 0.11 J 0.16 nd nd nd 0.30 0.07 J 2.23 0.12 J 0.75 nd nd nd 0.11J nd 0.31 J nd nd 0.15 J 0.06 J nd nd 0.42 nd 0.18 J 0.28 0.05 J nd nd nd 0.40 3.17 3.44
0.02 J nd nd nd nd nd nd nd 0.14 J 0.09 0.04 J 0.07 nd 0.09 nd 0.03 J 0.02 J 0.73 0.31 0.61 nd 0.10 0.48 0.12J 0.39 0.24 J 0.17 0.23 0.09 J 0.10 0.16 0.05 J 0.15 nd 0.03 J 0.10 nd nd nd nd 0.35 1.77 5.07
0.02 J nd nd nd nd nd nd nd 0.02 J nd 0.02 J 0.02 J 0.03 J 0.01 J nd 0.02 J 0.07 0.15 nd 0.07 nd nd nd 0.02J nd 0.07 J 0.03 J nd 0.04 J nd nd nd 0.02 J nd nd 0.18 nd nd 0.01 J nd 0.06 J 0.30 0.82
0.07 J nd nd nd nd nd nd nd nd nd 0.05 J 0.02 J nd nd nd nd 0.08 0.08 nd 0.05 J nd nd nd 0.02J nd nd nd nd 0.04 J nd nd nd 0.03 J nd nd 0.11 nd nd 0.01 J nd 0.07 J 0.21 0.46
0.04 J nd nd nd nd 0.03 J nd nd 0.05 J 0.02 J 0.03 J 0.05 0.07 J 1.38 nd nd nd 0.84 0.12 J 0.87 nd 0.22 nd 0.17J 0.02 J 0.17 J nd 0.03 J 0.05 J nd nd nd 0.09 0.09 J nd nd nd nd nd nd 0.18 2.05 1.34
0.02 J nd nd nd nd nd nd nd nd 0.05 J 0.17 J 0.15 0.10 J nd 0.01 J 0.58 nd nd nd 0.24 nd 0.26 nd 0.09J nd nd nd nd 0.16 J 0.28 nd 0.20 0.43 nd 0.26 J 0.21 0.04 J nd 0.02 J nd 0.37 0.49 3.70
nd nd nd 0.02 J nd nd nd nd 0.10 J 0.05 J 0.04 J 0.07 0.02 J 0.02 J 0.01 J 0.04 J nd 0.13 0.16 J 0.16 nd 0.12 0.34 0.08J 0.04 J nd nd 0.03 J 0.05 J 0.05 0.18 0.02 J 0.10 0.40 nd 0.46 0.29 1.20 0.13 0.02 J 0.25 0.57 7.31
nd nd 0.02J 0.06 J nd 0.08 nd 0.11 J 0.64 nd 0.31 0.26 nd 0.30 0.06 J nd 0.28 3.77 0.69 1.79 nd 1.27 0.78 0.75J 2.40 2.12 0.72 1.37 1.57 0.91 2.78 nd 1.76 0.90 0.26 2.25 nd nd 0.56 0.08 J 1.41 7.80 41.9
0.03 J nd 0.04J 0.05 J 0.04 J nd nd nd 0.20 0.25 0.10 J 0.09 0.08 J 0.04 J nd 0.07 J nd 1.55 0.40 0.49 nd 0.37 0.55 0.16J 0.31 1.29 nd 0.33 0.58 0.57 0.80 0.20 0.50 0.19 0.08 J 0.31 0.29 nd nd 0.14 J 0.63 2.81 13.5
nd nd nd 0.03 J nd nd nd nd nd 0.07 J 0.10 J nd 0.06 J 0.01 J nd 0.06 J nd nd nd nd 0.01 J 0.06 J 0.10 J 0.55J 0.56 0.15 J 0.08 J nd 0.16 J nd nd 0.01 J 0.07 J nd nd nd 0.03 J nd 0.18 0.03 J 0.17 J 0.07 J 4.16
J, Analyte concentration below corresponding Method Detection Limit (MDL); nd, not detected.
974
Volume 36/Number 12/December 1998 d e t e c t a b l e c o n c e n t r a t i o n s in s e d i m e n t s (1.38 ng/g). In general, high c o n c e n t r a t i o n s d e t e c t e d in s e d i m e n t s w e r e m a t c h e d by an i n c r e a s e d c o n c e n t r a t i o n in organisms an d vice versa. U n f o r t u n a t e l y , no live bivalves c ould be f o u n d in S a n t o D o m i n g o and P u e r t o Plata, locations with the highest c o n c e n t r a t i o n s o f trace o r g a n i c c o n t a m i n a n t s . It is p r e s u m e d that h a d bivalves b e e n f o u n d at t h e s e locations, c o n c e n t r a t i o n s in their tissues w o u l d have b e e n the g r e a t e s t m e a s u r e d in the D o m i n i c a n R ep u b lic .
Trace metals R es u l t s o f s e d i m e n t analyses are p r e s e n t e d in T a b l e 3. T h e data clearly show that for Cu, Hg, Pb an d Z n, highest c o n c e n t r a t i o n s are typically f o u n d in
s e d i m e n t s c o l l e c t e d n e a r the m o s t highly industrialized an d p o p u l a t e d cities (e.g. P u e r t o Plata and S a nt o D o m i n g o ) or at the m o u t h s of i m p o r t a n t river systems ( B a r a h o n a ) . M a x i m u m values for t h r e e o f the m e t a l s (Hg, Pb and Z n ) w e r e o b s e r v e d in s e d i m e n t s f r o m P u e r t o Plata which also c o n t a i n e d a high c o n c e n t r a t i o n of Cu. It should be noted, however, that this s a m p l e was c o l l e c t e d within the area o f the c o m m e r c i a l / r e c r e a tional p o r t o f P u e r t o Plata. In contrast, s e d i m e n t s far r e m o v e d f r o m industrial or riverine inputs, such as P e d e r n a l e s at the southwest en d o f the co unt r y and Isla S a o n a and S a b a n a de la M a r in the e a s t e r n sector, c o n t a i n e d relatively low c o n c e n t r a t i o n s o f all the metals analysed. C o n c e n t r a t i o n s of metals in oysters and clams f r o m various sites are given in T a b l e 4. As m e n t i o n e d ,
TABLE 2
Chlorinated hydrocarbon concentrations (ng/g, dry wt) in bivalve samples from the Dominican Republic. Location Station # Species Lipid weight (%) Hexachlorobenzene Alpha HCH Beta HCH Gamma HCH Delta HCH Heptchlor Heptachlor epoxide Oxychlordane Gamma chlordane Alpha chlordane
Trans-Nonachlor Cis-Nonachlor Aldrin Dieldrin Endrin Mirex 2,4' DDE 4,4' DDE 2,4' DDD 4,4' DDD 2,4' DDT 4,4' DDT PCB8/5 PCB18/I 7 PCB28 PCB52 PCB44 PCB66 PCB101/90 PCB118 PCB153/132 PCBI05 PCB138/160 PCB187 PCB128 PCB180 PCB195/208 PCB206 PCB209 Total HCHs Total chlordanes Total DDTs Total PCBs
Montecristi 1
Crassostrea rizophorae 2.93 0.37J nd nd nd nd nd nd nd nd 0.29 nd 0.22J 0.66J nd nd 0.30J 0.59 9.34 0.48 0.66 nd nd 3.93 2.20 0.09J 2.58 1.17 2.25 0.39 0.06J 0.47J nd 0.65J 0.17J nd nd 0.81 nd nd nd 0.51 11,1 32.3
Rio San Juan 3
Samana 5
Sanchez 6
Isognomon Crassotrea Crassotrea alatus rizophorae rizophorae 12.9 0.28 nd nd 0.39 0.77 nd nd 0.09J 0.07J 0.73 nd 1.09 1.73 nd 1.88 1.94 0.19 5.76 nd 0.51 nd 0.79 1.13 2.71 0.37 2.86 0.24J 0.29 0.21 0.42 1.26 nd 0.54 nd nd nd 1.93 nd nd 1.16 1.97 7.24 26.2
Sabana de la Mar 7
Crassotrea rizophorae
Miches 8
Isla Saona 9
Crassotrea Codakia rizophorae obicularis
San Pedro 10
Barahona 13
Tellina Isognomon fausta alatus
4.36
2.31
2.15
2.31
6.72
5.19
nd nd 0.18J nd 0.62 0.48 0.69 nd 2.22 2.17 1.10 0.82 1.47 0.93J nd nd 0.97 13.2 3.09 5.88 0.34 nd nd nd 4.41 3.47 1.56 4.86 2.43 1.25 2.42 0.35 1.67 0.37 0.12.I nd nd nd nd 0.80 7.47 23.4 51.2
0.29J nd nd nd nd nd nd nd 0.21J 0.59 0.17J nd nd nd nd nd 0.77 10.1 0.14J 0.93 nd 0.74 nd 2.45 nd nd 1.54 1.29 1.12 nd 0.55J nd 0.53J 0.09J nd 1.19 0.14J nd nd nd 0.96 12.7 19.5
0.32J nd 0.14J nd 0.09J nd nd nd 0.37J !.53 0.47 0.78 1.14 nd nd 1.50 0.68 11.8 0.47 1.89 nd 0.34J nd 1.26 nd 5.15 1.08 0.87 1.30 nd 1.28 nd 1.02 0.22J 0.51J 1.07 nd nd nd 0.23J 3.15 15.2 30.1
0.25J nd nd nd 0.13J nd nd 0.59 0.46 0.86 0.66 0.32J 2.42 10.4 0.43 nd 0.54 24.2 0.93 4.01 nd 0.56 2.32 1.15 nd nd 0.74 nd 1.30 nd 1.29 nd 0.88 nd 0.23J 2.37 nd nd nd 0.13J 2.91 30.2 22.5
0.15J nd nd nd nd nd nd nd nd 1/.56 nd 0.22 0.25J nd nd 0.64 nd 0.08J nd nd nd nd 3.34 nd nd nd 0.37 0.91 0.2[) nd nd nd 0.34 nd nd nd nd nd nd nd 0.79 0.08J 11.3
nd nd 0.81 nd 0.50 nd 0.42 nd 1.26 nd nd 0.47 1.47 nd nd 0.29 0.17 3.22 nd 1.39 0.10J nd 3.43 nd nd 0.46J 0.98 1.89 0.70 0.72 1.89 0,36 1.24 4.38 0.19J 7.27 3.57 1.24 0.57 1.30 2.15 4.87 61.9
16.2 nd nd nd 0.08J 0.57 nd 0.61 nd 0.24 1.04 0.46 0.65 1.39 0.36J nd 0.53 0.53 15.2 2.87 5.94 1.65 4.78 4.92 nd 1.26 1.15 0.88 2.56 2.05 3.74 6.16 1.89 4.04 0.58 1.64 5.54 nd nd nd 0.65 3.00 30.9 82.3
J, Analyte concentration below corresponding Method Detection Limit (MDL); nd, not detected. 975
Marine Pollution Bulletin TABLE 3
Trace metal concentrations (lag/g, dry wt) in sediment samples from the Dominican Republic. Location Puerto Plata Rio San Juan Samana Sanchez Sabana de la mar Miches Isla Saona San Pedro Santo Domingo Barahona Pedernales
Stn # 2 3 5 6 7 8 9 10 11 13 14
OC (%) CaCO3 (%) 2.4 9.5 0.82 0.75 0.68 1.8 11 3.7 4.1 5.5 4.0
79 76 54 73 78 26 37 3.2 74 79 79
A1
Cd*
18800 0.315, 0.435 3310 0.099, 0.150 0.277, 0.279 4900 0.120,0.181 0.038, 0.056 33000 0.147,0.149 623 0.049, 0.051 13100 0.028, 0.043 0.255, 0.273 0.186, 0.198 276 0.074, 0.091
Cr
Cu*
74.4 65.3 63.2 36.8 38.3 186 8.88 32.1 125
59.8,80.3 6.64,7.90 19.3 17.5,29.4 19.6 102, 111 4.04, 4.82 17.9,25.5 103 31.8, 34.6 1.01,1.63
10.3
Fe
Hg*
Ni
24500 0.392, 0.433 4640 0.140, 0.154 0.186, 0.368 34700 0.122, 0.230 0.151, 0.156 48700 I).186,0.282 603 0.099, 0.133 16500 0.128, 0.212 0.407, 0.565 0.122, 0.401 230 0.096, 0.098
Pb*
Zn*
67.7 81.8, 134 30.8 6.66,9.79 16.6, 17.2 50.0 4.44,8.64 3.63, 4.73 124 9.20, 14.9 4.38 2.57, 5.24 16.8 4.73,5.59 37.2, 57.4 36.8, 38.6 1.71 0.42, 2.69
202, 244 13.(I,19.7 56.9 52.0, 56.2 42.9 91.6,98.6 4.52, 7.76 37.1, 40.8 184 85.7, 99.4 2.34, 3.91
*Two separate analyses are shown. bivalves were not available at all stations where sediments were collected; therefore, comparisons with sediment data can only be m a d e at certain sites, and then only a m o n g the same species of bivalves. T h e oysters (Crasssostrea rizophorae) f r o m stations in Bahia S a m a n a showed no consistent trends in c o n t a m i n a n t levels. L e a d and Z n levels were highest in oysters from S a m a n a whereas maximum levels of Cu, Ni and Cr were found in samples from Sanchez. Concentrations in a n o t h e r species of oyster (Isognomon alatus, flat tree-oyster) collected at B a r a h o n a and Rio San Juan did not suggest contamination except perhaps for the somewhat e n h a n c e d levels o f Pb, Ni and Cu at B a r a h o n a where similarly elevated concentrations of predominantly a n t h r o p o g e n i c Cu, Pb and Zn were m e a s u r e d in sediments. While c o m p a r i n g metal concentrations in both species of oysters, it is interesting to note the marked differences in A1, Cd and Cu levels. Concentrations of these metals were a factor of 10-100 times lower in the fiat tree-oyster. A l t h o u g h these oysters were collected from different locations along the Dominican Republic coastline and, therefore, might be exposed to different environmental levels of trace metals which could explain this dissimilarity, no significant differences are observed in the concentrations of the remaining reported metals~ including Hg. T h e different ability to concentrate organic and inorganic chemicals by different bivalves has been discussed by O ' C o n n o r et al. (1994).
Mercury in bivalves and sediments from the Bahia S a m a n a area are of particular interest since there are reports that some 270 years ago two Spanish vessels carrying 400 tonnes of pure mercury sank off Cabo San Rafael near Miches in approximately 1 3 m depth (Peterson, 1979). A t t e m p t s to excavate the ship for treasure using subsediment air hoses were carried out in 1978 and, in fact, vivid descriptions of the liquid mercury f o u n d in the sediments at the time of the excavation have been reported (Peterson, 1979). W a t e r circulation into Bahia S a m a n a from the wreck area is along the n o r t h e r n coast and out through the middle section of the bay. W a t e r discharged into the inner portion of the bay by the Y u n a River is transported seaward along the west and southern coasts of Bahia Samana. It is therefore noteworthy that, despite such a t r e m e n d o u s input source of Hg in this region, none of the sediments from nearby stations in the Bahia Samana, particularly Samana, Sabana de la Mar and Sanchez, contained elevated concentrations of Hg. This could reflect net burial and isolation of the source by continual resuspension and sedimentation events; however, verification of this hypothesis requires a much m o r e t h o r o u g h study of the bay area including sediment cores to establish temporal and spatial trends. Nevertheless, the very high concentration of Hg (7.02 lag/g dry wt) detected in oysters from Sabana de la Mar does suggest a significant source of anthropogenic contamination in this area. Likewise, Hg was
TABLE 4
Trace metal concentrations (lag/g, dry wt) in bivalve samples from the Dominican Republic. Location
Stn #
Montecristi Samana Sanchez Sabana de la Mar Miches Rio San Juan Barahona
1 5 6 7 8 3 13
Isla Saona San Pedro
9 10
976
Species Oysters Crassotrearizophorae Crassotrearizophorae Crassotrearizophorae Crassotrearizophorae Crassotrearizophorae lsognomon alatus Isognomon alatus Clams Codakiaorbicularis Linn6 Tellinafausta
AI
Cd
Cr
650 316 2240 319 287 59.5 26.0
0.35 1.15 1.74 2.57 1.87 0.26 0.24
4.83 2.88 10.7 1.73 1.92 4.96 2.38
162 201 866 301 112 7.58 19.7
0.30 0.04
1.66 4.15
3.08 14.1
3.80 996
Cu
Fe
Hg
Ni
Pb
Zn
750 495 3400 415 369 277 253
0.49 0.55 7.02 1.38 0.98 0.59
1.74 2.15 7.92 1.73 1.34 1.25 2.90
0.57 1.46 0.81 0.08 0.09 0.25 1.44
1500 4380 2030 2570 1050 4000 4010
50.9 1080
0.29 0.75
1.57 4.91
0.73 0.30
22.9 51.4
Volume 36/Number 12/December 1998
high in oysters from nearby Miches (Table 4). Sediments from these two stations did not show the same degree of Hg enhancement (Table 3), hence, it is difficult to discern the origin of the high Hg levels measured in these bivalves. It may be that low level, chronic Hg inputs from local sources rather than any residual Hg from the nearby shipwreck site are responsible for the observed contamination. Furthermore, it is of interest that Hg levels in bivalves (mean = 0.61, range 0.29-0.98 lag/g dry wt) from six other stations around the island are, on average, relatively high when compared with concentrations in similar species from other areas (e.g. NOAA, 1987; Claisse, 1989). For example, Hg concentration in oysters averaged 0.21 +0.09 lag/g dry weight in 1869 samples collected from the French Atlantic and Mediterranean coasts between 1979 and 1993 (RNO, 1995). Based on our preliminary findings with bivalves, we suggest that a more detailed study of Hg, particularly around Bahia Samana, is warranted.
Data comparison Total selected chlorinated hydrocarbon and trace metal concentrations in bivalve samples and nearshore sediments reported for different Caribbean and tropical west Atlantic locations are listed in Table 5 and Table 6. Although comparisons of data among different studies are generally complicated because the methods used in each are rarely standardized, it is worthwhile looking at some of the published data to put the contamination problems in the Dominican Republic into perspective. In general, information on the levels of these organic compounds and metals in the area is scarce. A comparison of the chlorinated hydrocarbon concentrations measured in the
Dominican Republic with recently reported levels in samples from the Caribbean area shows that these concentrations compare well with the published findings. For example the ranges of concentrations for total chlordanes, DDTs and PCBs reported in bivalves from Puerto Rico, collected between 1991 and 1994 as part of the NOAA's National Status and Trends Program, are comparable with the ranges determined during this study (Table 5). Possible exceptions are the high total DDT concentrations encountered in bivalves samples from Barahona (30.9 rig/g), Miches (30.2 ng/g) and Samana (23.4 ng/g). Similar high concentrations were encountered in oyster samples collected near Port Royal, Jamaica (24.0ng/g) during the International Mussel Watch - - Phase I (Sericano, unpublished results). Except for the relatively high total DDT concentrations in sediments from Puerto Plata (12.5 ng/g) and Santo Domingo (7.80 rig/g), the levels of these pesticides in the Dominican Republic and Puerto Rico are comparable. A similar situation is observed for PCBs; concentrations encountered in sediments from Puerto Plata (25.3 ng/g) and Santo Domingo (41.9 ng/g) are outside the range of concentrations measured in sediments from Puerto Rico. Trace metal concentrations in sediments from the most contaminated areas in the Dominican Republic were not exceptional when compared with those reported for other coastal areas throughout the world (Fowler, 1990). For the Caribbean region, much lower concentrations of Cu and Fe have been reported in sediment samples from nearshore locations in Tobago (Rajkumar and Persad, 1994); however, significantly higher concentrations of mercury, lead and zinc were found in sediments collected around a Havana sewage outfall (Gonzalez and Torres, 1990). Nevertheless, the trace metal levels reported here are similar to, or in
TABLE 5 Mean and range of chlorinated hydrocarbon concentrations (ng/g, dry wt) in nearshore surface sediments and bivalve samples from the Caribbean and tropical West Atlantic areas.
Location
Year
Total Chlordanes
Total DDTs
Total PCBs
1995
0.51 _ 0.55 (
2.88 + 3.89 (0.21-12.5) 0.91 +0.32 (0.36-1.52) ( < MDL- 17.7)
9.73 _+12.9 (0.46-41.9) 10.5 -+5.4 (5.03-22.7)
15.1 -+ 11.0 ( < MDL-30.9) 5.03 -+3.41 (2.08-10.2) 1.40 -+0.61 (1.00-2.10) 4.67 -+2.72 (3.00-7.80) 2.47 14.7 -+ 13.1 (5.44-24.0) 2.27 _+2.54 (0.47-4.06)
37.5 -+ 23.0 (11.3-82.3) 31.9 -+ 14.2 (18.3-55.1) 24.5 -+ 17.8 (3.80-36.1) 58.5 -+25.4 (32.3-83.0) 15.3 20.2 __+7.43 (14.9-25.4) 12. l + 4.96 (8.54-15.6)
Reference
Sediments
Dominican Republic Puerto Rico Mexico
1991/1992 1992
This study GERG, 1993 Gold-Bouchot et al., 1993
Bivalves
Dominican Republic Puerto Rico
1995 1991/1992 1992/1993 1993/1994
Cuba Jamaica
1992 1992
Trinidad and Tobago
1992
2.55 -+2.10 (0.51-7.47) 0.39 __+0.56 (0.79-3.79) < MDL 1.20 -+0.78 (0.70-2.10) 4.08 4.64 +__4.59 (1.39-7.88) 1.72 ± 0.94 (1.05-2.38)
This study GERG, 1993 GERG, 1994 GERG, 1995 IMW Program, Sericano unpublished results IMW Program, Sericano unpublished results IMW Program, Sericano unpublished results
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Marine Pollution Bulletin TABLE 6 M e a n + S D and range (in parentheses) of heavy metal concentrations (lag/g, dry wt) in nearshore surface sediments and bivalves from the Caribbean and tropical West Atlantic areas Location
AI
Cd
Cr
Cu
Fe
Sediments Dominican Republic Guadaloupe Trinidad Tobago
Hg
10600_+ 12000 0.159_+0.109 64.0_+54.8 37.3_+38,1 18600_+18500 0.230_+0.123 (276-33000) (0.028-0,435) (8.88-186) (1.01-111) (230-48700) (0.096-0.565) (9.3-187) (2,4-68) 0.626_+0.350 2,89_+2.53 2380_+1960 10,040-2.12) (0.06-16,0) (12.4-15700) (4-297) (0,01-7.2) Cuba Cuba (<63 lam) 8800 96 240 24 80(I 17.3 (4400-20000) (22-339) (18-716)(8300-57600) (0,64-76) (63-150 ~tm) 6000 73 172 17 900 7.9 (2300-15 800) (22-225) (24-567) (0.48-32) Bermuda (1-86) Brazil (21-28) (0.050-/I.150) (4.9-75) Mexico Bivalves Dominican Republic Venezuela
544_+712 0.947_+0.917 3.91 _+2.86 187+275 788+1030 (3.80-2240) (0.04-2.57) (1.66-10.7) (3.08-866) (50.9-3400) 0.61_+0.19 0.82_+0.26 27.0_+10.4 10.33-0.91) (0.46-1.2) 114.0-49.1) Mexico (Gulf coast) 4.2_+ 1.8 324_+ 115 958_+546 ( 1.2-7.8) ( 161-662) 1170-2650) 3.25_+1.43 0.42_+0.19 97.0_+47.7 USA (SE coast) (SE coast) (1.4-10.5) (0.11-0.88) (50-337) (Gulf coast) 4.09_+1.64 0.66_+0.34 126_+63.2 (0.96-8.83) 10.13-1.30) 19.66-417)
some cases lower than, concentrations in sediments from other Caribbean or tropical Atlantic sites (Table 6). Although a similar scenario can be observed when comparing bivalve data, comparative data are much scarcer (Table 6). Concentrations measured in samples from the Dominican Republic are, with some exceptions, comparable with previous reports in samples from Mexico and Venezuela. On the one hand, chromium concentrations reported here appear to be elevated when compared with bivalves from the Morrocoy National Park in Venezuela (Jaffe et al., in press). On the other hand, significantly higher concentrations of other metals, particularly Pb and Cd, have been measured in oysters from a tropical Mexican lagoon (Vazquez et al., 1993). In general, the bivalve data do not suggest any major source of heavy metal contamination in Dominican Republic except for Hg in the vicinity of Bahia Samana. Conclusions The analysis of selected trace organic contaminants and trace metals in bivalve and sediment samples from coastal areas of the Dominican Republic allowed us to define the geographical distributions of these contaminants and identify some areas with high concentrations. DDT and its metabolites, DDD and DDE, were the most abundant chlorinated pesticide detected in the samples analysed. PCB concentrations were generally higher than concentrations detected for chlorinated pesticides and the highest concentrations were detected near large industrialized areas and ports. A similar correlation was observed for predominantly anthropo978
Ni
Pb
Zn
42.2_+43.3 22.9_+31.9 86.2_+79.1 (1.71-124) (0.420-134) (1.96-277) (1.7-236) 119-664) (2.4-30.5) 4.01 _+2.04 8.87_+9.74 (0.30-20.9) (0.10-39.3) (8-340) (8-646) 46 280 794 (11-112) (44-903) (72-3740) 35 229 644 (3.5-94) (50-967) (68-3220) (3-157) (15-178) (43-88) 1102-151) (17-91)
(21-130)
Reference This study Bernard, 1995 Hall and Chang-Yen, 1986 Rajkumar and Persad, 1994 Gonzalez and Brugmann, 1991 Gonzalez and Torres, 1990 Gonzalez and Torres, 1990 Burns et al., 1990 Knoppers et al., 1990 Lacerda et al., 1993 Paez Osauna et al., 1986
1.51 _.+2.25 2.83_+2.20 0.637_+0.529 2180_+1680 This study (0.290-7.02) (1.25-7.92) 10.08-1.46) (22.9-4380) 15.2_+2.25 0.560_+0.09 910_+580 Jaffe et al., in press (10.6-17.8) (0.40-0.71) (250-2050) 8.84_+4.68 620_+268 Vazquez et al., 1993 (2.9-24.2) (200-1320) 0.07_+0.04 2.38_+1.14 0.32_+0.11 2750_+1100 NOAA, 1987 10.01-0.13) (0.6-6.56) 10.11-0.93) (1000-5500) 0.13_+0.10 2.18_+0.91 0.57_+0.30 1910_+1060 NOAA, 1987 (0.02-0.40) 10.55-12.56) (0.09-2.33) (73-8000)
genic metals (Cu, Hg, Pd and Zn). A comparison of contaminant concentrations observed during this study with those reported for similar environments in the Caribbean and west Atlantic coastal areas indicates that levels of most of these analytes in the coastal marine environment of the Dominican Republic are similar to or in some cases lower than the concentrations reported in those studies. However, in the case of Hg, it is noteworthy that relatively high concentrations were found in bivalves living in the vicinity of a known major source of Hg contamination in Bahia Samana. A thorough study of this area to delineate the extent of potential Hg contamination from that source is recommended. This work was supported in part by IAEA Technical Cooperation Project DOM/7/002. The authors wish to thank Ms S. Azemard, Ms A. Dean, Ms N. Eaker and Ms R. Stevenson for assistance with the metal analyses and Ms D. Frank for assistance with the chlorinated hydrocarbon analyses. The IAEA Marine Environment Laboratory operates under an agreement between the International Atomic Energy Agency and the Government of the Principality of Monaco. Bernard, D. (1995) Metals in sediments from two lagoons off Guadaloupe West Indies. Marine Pollution Bulletin 30, 619-621. Bloom, N. S. (1992) On the chemical form of mercury in edible fish and marine invertebrate tissue. Can. J. Fish. Aquat. Sci. 49, 1010-1017. Bloom, N. S. and Crecelius, E. A. (1987) Distribution of silver, mercury, lead, copper and cadmium in central Puget Sound sediments. Mar. Chem. 21, 377-390. Burns, K. A., Ehrhardt, M. G., Pherson, J. M., Tierny, J. A., Kananen, G. and Connelly, D. (1990) Organic and trace metal contaminants in sediments, sewater and organisms from two Bermudan harbours. J. Exper. Mar. Biol. Ecol. 138, 9-34.
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