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

Marine Environmental Research 29 (1990) 161-203

N O A A ' s Status and Trends Mussel Watch Program: Chlorinated Pesticides and PCBs in Oysters (Crassostrea virginica) and Sediments from the Gulf of Mexico, 1986-1987

Jos6 L. Sericano, Elliot L. Atlas, Terry L. Wade & James M. Brooks Geochemical and Environmental Research Group, Department of Oceanography, Texas A & M University, 10 S. Graham Rd., College Station, Texas 77845, USA (Received 15 September 1988; revised version received 31 October 1989; accepted 27 September 1989)

ABSTRACT Chlorinated pesticides and PCBs were analyzed in more than 590 oyster and sediment samples collected during 1986 and 1987, the first 2 years of the NOAA's Status and Trends Mussel Watch Program established to monitor the current status and temporal trends of these contaminants in the Gulf of Mexico. Chlorinated hydrocarbons in oysters and sediments presented similar distribution patterns; however, their concentrations in oysters were several times higher than the concentration detected in the surrounding sediments. Alpha-chlordane, trans-nonachlor and dieldrin were the most abundant non-DDT pesticides in both types of sample. The major fraction of DD T related compounds measured in oysters and sediments was DDD. Based on average PC B concentrations, penta-, hexa-, and tetrachlorobiphen yls were preferentially accumulated by oysters as compared to the average sediment composition. Although this study was designed to avoid known point-sources of contaminant inputs, the measured concentrations were, in general, within the range of concentrations previously reported for the Gulf of Mexico. After the first 2 years of this program, the geographical distribution of chlorinated hydrocarbons in oysters and sediments is well defined. In contrast, the temporal trends at the different sites are not clear. Continued sampling will allow the identification of long-term trends in concentrations of chlorinated hydrocarbons in the Gulf of Mexico. 161 Marine Environ. Res. 0141-1136/90/$03"50 © 1990 Elsevier Science Publishers Ltd, England. Printed in Great Britain

162

Josh L. Sericano et al.

INTRODUCTION Contamination of the marine environment associated with chlorinated pesticides and polychlorinated biphenyls (PCBs), together with other organic and inorganic pollutants, has received increasing attention over the last several years. Particular attention has been focused on the coastal zone and estuaries, especially near large population centers (e.g. Farrington et al., 1982, 1983; Risebrough et al., 1983). These environments receive the largest impact of chemical contamination and may be the most sensitive areas to the accumulation of toxic compounds. Toxic organic compounds of synthetic origin, such as pesticides and PCBs, can be present at high concentrations (ppm) in the coastal marine environment, can affect the productivity of marine organisms and may ultimately be hazardous to human health. Since 1986, the Geochemical and Environmental Research Group (GERG) in the Department of Oceanography at Texas A & M University has been involved in the National Oceanic and Atmospheric Administration's Status and Trends Mussel Watch Program. This program is designed to monitor the current status and long-term trends of selected environmental contaminants, e.g. chlorinated pesticides, PCBs, polynuclear aromatic hydrocarbons and trace metals, along the Atlantic, Pacific and Gulf of Mexico coasts of the United States of America by measuring the concentrations of these contaminants in bivalves and sediments. Bivalves have been shown to be valuable sentinel organisms reflecting the current contaminant loading of an ecosystem (Farrington et al., 1980, 1982, 1983). In contrast, sediments reflect the longer term contaminant loading of the environment (Pruell & Quinn, 1985; Shaw et aL, 1985). Chlorinated pesticide (hexachlorobenzene (HCB), lindane, heptachlor and its epoxide, aldrin, alpha-chlordane, t r a n s - n o n a c h l o r , dieldrin and mirex) and PCB concentrations in oysters and sediments resulting from the first 2 years (1986 and 1987) of the NOAA's Status and Trends Mussel Watch Program for the Gulf of Mexico are presented here. The aim of this study is to (1) define the geographic distributions of contaminant concentrations in oysters and sediments along the north coast of the Gulf of Mexico, (2) estimate the variability in contaminant concentrations within and between sites, and (3) identify 'problem' areas.

MATERIALS AND METHODS Sampling In 1986, 147 oyster and 153 sediment samples were collected from three

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stations at 49 and 51 sites, respectively, over a 3-month period starting in January. In 1987, oysters and sediments were sampled during January and February at 48 and 50 sites with a total of 143 and 148 samples, respectively. The distance between stations within each site varied from 100 to 1000 m. Although the selected sampling sites for this study represent a broad range of environmental conditions from the USA-Mexico border to southernmost Florida with a wide spectrum of possible contaminant loadings, they were specifically chosen to avoid known point-sources of contaminant inputs. Site locations are shown in Fig. 1. The methods used for sample collection varied among sites depending on water depth. At shallow depth, sediments were directly scooped with a Tefon-coated scoop and oysters were collected by hand. At deeper stations, a box core and tongs or dredge were used for sediment and oyster samples, respectively. The top 1-2 cm sediment layer was collected in either case. Approximately 60 g of sediment were stored frozen in pre-combusted glass jars with Teflon-lined screw caps. Oyster shells were scrubbed free of mud and attached organisms, opened (20 per station) in the laboratory van under non-contaminating conditions, pooled in pre-combusted glass jars with Teflon-lined screw caps and stored frozen until analyzed. Before pooling, small pieces of mantle and gonadal tissues were removed from each oyster for the evaluation of P e r k i n s u s (a parasite) prevalence and severity and for a gonadal/somatic index assay.

Materials

The analytical procedure used was based on a method developed by MacLeod et al. (1985) with a few modifications that proved to be equivalent or superior to the original techniques. The analytical scheme is summarized in Fig. 2 and the important steps are discussed here. Pre-cleaning of all glassware involves extensive washing with Micro cleaning solution, rinsing with distilled water and combustion at 400°C for 4 h. All solvents are glassdistilled nanograde purity, e.g. Burdick & Jackson. Solvent purity is checked, after 300-fold concentration, by gas chromatography with electron capture detector (GC-ECD). Each set of samples (8-10) is accompanied by a complete system blank and spiked blank or reference material that are carried through the entire analytical procedure and evaluated by GC-ECD. Before extraction, 4,4-dibromooctafluorobiphenyl (DBOFB) is added to all samples, blank and spiked blank as internal standard. DBOFB, which does not co-elute with naturally occurring substances under our analytical conditions, is added at a concentration similar to that expected for the sample components of interest.

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Extraction and column chromatography Approximately 50 g of sediment (wet weight) are used for analysis. The sediments are sequentially extracted on a roller table with 100ml of methanol (1 h), 100 ml of 1 : 1 methanol:methylene chloride (1 h) and three portions of 100 ml of methylene chloride (16, 3 and 1 h, respectively). The combined extracts are partitioned into two phases by addition of acidic NaC1 solution (pH = 2). The organic phase is concentrated to 10-15 ml in a fiat-bottom flask equipped with a three-ball Snyder condenser. Activated granular copper is added to the extract during concentration to remove elemental sulfur. Kuderna-Danish tubes are heated in a water bath at 60°C, to concentrate the extracts to a final volume of 2 ml in hexane. Approximately 15 g of wet tissue are used for the analysis of chlorinated hydrocarbons in oysters. After the addition of 50 g of anhydrous Na2SO 4, the tissue is extracted three times with 100 ml of methylene chloride using a 'Tissumizer' homogenizer. A 20 ml sub-sample is removed from the total volume and concentrated to 1 ml for lipid weight determination. The combined extracts are concentrated as previously described. Sediment and tissue extracts are fractionated by alumina:silica (80-100 mesh) column chromatography. The silica gel is activated at 170°C for 12 h and partially deactivated with 5% distilled water (v/w). Twenty grams of silica gel are slurry packed in methylene chloride over 10g of alumina. Alumina is activated at 400°C for 4 h and partially deactivated with 1% distilled water (v/w). Activated copper is added to the top of the column for sediment samples to remove any residue of elemental sulfur. The methylene chloride is replaced with pentane and the extract is applied to the surface of the column. The column is sequentially eluted with 50ml of pentane (fl), 200 ml of 1 : 1 methylene chloride :pentane (f2) and, for sediments, 50 ml of methanol (f3). The f2 fraction, which contains the chlorinated hydrocarbons, was concentrated as previously described. The f2 fraction from oyster samples is further purified by Sephadex LH20 column (25-100 mesh) to remove lipids (Ramos & Prohaska, 1981). The column is eluted with 140 ml of a 6: 4: 3 cyclohexane: methanol: methylene chloride mixture. The first 40 ml are discarded and the next 100 ml fraction is concentrated to a final volume of 0"5-1 ml, in hexane, for gas chromatographic analysis.

Instrumental analysis Pesticides and PCBs are analyzed by fused-silica capillary column G C - E C D a Varian 3500 GC or a Hewlett-Packard 5880A GC in splitless mode. Capillary columns, 30 m long × 0.25 m m i.d. with 0.25/~m

(Ni63) using either

NOAA's Status and Trends Mussel Watch Program

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DB-5 film thickness, are temperature-programmed from 100 to 140°C at 5°C min-1, from 140 to 250°C at 1.5°C min-1 and from 250 to 300°C at 10°C m i n - 1 with 1 min hold time at the beginning of the program and before each program rate change. A hold time of 5 min is used at the final temperature. Total run time is 94-33 min. Injector and detector temperatures are set at 275 and 325°C, respectively. Helium is used as carrier gas at a flow velocity of 30.0cm s-1 at 100°C. Nitrogen is used as make-up gas at a flow rate of 20 ml min-1. The volume injected is 2 #1. Pesticides are quantitated against a set of authentic standards containing organochlorine pesticides at known concentrations which are injected at three different concentrations to calibrate the instrument and to compensate for a non-linear response of the electron capture detector. PCB congeners of the same degree of chlorination are quantitated in comparison to a single reference congener of known concentration within each group. The reference congeners used for quantitation were isomers number 7, 31, 47, 101,153, 185, 194 and 206. The numbering of PCB isomers, done according to Ballschmiter & Zell (1980), is as follows: numbers 1-3 represent mono-, 4-15 di-, 16-39 tri-, 40-81 tetra-, 82-127 penta-, 128.-169 hexa-, 170-193 hepta-, 194-205 octa-, 206-208 nonachlorobiphenyls and 209 decachlorobiphenyl. The detection limits for organochlorines and individual PCB isomers, calculated on the basis of 15 g (wet weight) tissue and 50 g (wet weight) sediment sample sizes with 0"2% by volume of the extract injected into the G C - E C D , are 0"25 and 0.02 ng g- 1 dry weight for oysters and sediments, respectively. In this report, most of the analyte concentrations have been aggregated into classes. D D T and its metabolites have been combined into a single class, total DDTs. Total (non-DDT) pesticides is the sum of HCB, lindane, heptachlor and its epoxide, aldrin, alpha-chlordane, trans-nonachlor, dieldrin and mirex while total PCB represents the sum of all the measurable PCB congeners in the samples.

Quality control/quality assurance (QC/QA) Several quality assurance activities have been undertaken to ensure that the data produced during the Status and Trends Program are reproducible, accurate and free from analyst bias. The quality assurance program has included several laboratory intercalibration exercises. Intercalibrations involved repeated, routine analysis of homogenated samples (natural sediments and mussel tissues) supplied by the National Institute of Standards and Technology (NIST), formerly National Bureau of Standards (NBS), to be intercompared with other laboratories. Certified concentrations of analytes are not available for these materials. Thus, results can be compared only among laboratories and within single laboratories.

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The results of these intercalibrations demonstrated interlaboratory comparability on the order of 20-30% , which is typical for such exercises. A complete report of several intercalibration exercises is being prepared by NIST. Interim reference material as well as spiked blanks were also analyzed along with each sample set as part of the laboratory QA/QC program. Evaluation of the analytical methods and sources of error are a continuing and ongoing process in order to improve the reliability and intercomparability of the data.

Ancillary parameters Sediment total organic carbon were determined on sub-samples of the samples for trace organic analyses with a Leco WR-12 Total Carbon System. Sediment sub-samples (0.2-0-5 g) are treated with concentrated HC1 dropwise until no degassing is observed. The treated samples are dried at 50°C for 24-36h. The dried samples are then transferred to a sintered crucible, mixed with iron accelerator and tin coated copper catalyst, and analyzed by total combustion on the Leco WR-12 instrument. Organic carbon is converted to CO2 and measured with a non-dispersive infrared spectrophotometer. Grain size analysis was performed by the procedure of Folk (1974). Briefly, refrigerated samples are homogenized, treated with 30% H20 2, to oxidize organic matter, and washed with distilled water, to remove soluble salts. Sodium hexametaphosphate is added to deflocculate each sample before they are wet-sieved through a 62.5 micron (4-0 phi) sieve to separate gravel and sand from the silt--clay fraction. The total gravel and sand fraction is then oven dried at 40°C, weighed, and sieved at 0"5 intervals from - 1 . 5 to 4.0phi. The silt-clay fraction is analyzed for particle size distribution by the pipette (settling rate) method at 4"5, 5"0, 5"5, 6"0, 7.0, 8"0, 9.0 and 10.0 phi intervals. Lipid contents in oysters were determined on a sub-sample of the extracts of the pooled trace organic samples as mentioned in the extraction and column chromatography section.

Statistical analysis One-way analysis of variance (ANOVA) on the chlorinated hydrocarbon concentrations in oyster and sediment samples was performed in order to detect significant increases or decreases in analyte concentrations, at each site, between 1986 and 1987. Since environmental data often present a nonsymmetrical distribution, commonly skewed to the right, it is necessary

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to transform the data to a new scale where the assumptions of normality and equality of population variances are not violated. For this study, data were transformed to a logarithmic scale and a probability limit of 0"05, i.e. = 0"05, was used (Snedecor & Cochran, 1980; Ott, 1984). Spearman's rank correlation was used to determine relationships between different parameters, e.g. chlorinated hydrocarbon concentrations in oysters or sediments with lipid percentages or % fine particles and organic carbon contents, respectively. RESULTS

Sediment analyses A total of 301 sediment samples were analyzed for HCB (hexachlorobenzene), lindane, aldrin, heptachlor, heptachlor epoxide, alpha-chlordane, trans-nonachlor, dieldrin, mirex, o-p' DDE, p-p' DDE, o-p' DDD, p-p' DDD, o-p' DDT, p-p' D D T and PCB isomers during the first 2 years of the Status and Trends Mussel Watch Program for the Gulf of Mexico. Percent incidence, mean concentrations, range and distribution frequency for each analyte in the Gulf of Mexico as well as the sum of individual compounds within each category, i.e. total (non-DDT) pesticides, DDTs and PCBs, are presented in Tables 1 and 2. Because trace organic analyses occasionally yield extremely high values that can strongly bias a mean, the median is also shown. Average total concentrations in sediments are shown in Figs 3 to 5. Error bars represent + 1 standard deviation. The sites are geographically ordered from the USA-Mexico border (Site No. 1) to the southern-most site in Florida (Site No. 51). It is important to note that the reported mean total concentrations include contributions equal to the detection limits for those analytes that were not detected. Thus, there is no site for which an average value of zero is reported. Chlorinated hydrocarbons in sediments were generally present in low ng g- 1 to sub ng g- 1 concentrations. During the first year, total (non-DDT) pesticides, i.e. the sum of HCB, lindane, heptachlor and its epoxide, aldrin, alpha-chlordane, trans-nonachlor, dieldrin and mirex, ranged from <0.02 to 20.5ngg -1 with a mean concentration of 1.07_+ 1-92ngg -1 (median=0.58ngg-1). Trans-nonachlor, dieldrin and alpha-chlordane represented the major fractions of this total and were measurable in 71, 73 and 77% of the samples with concentrations ranging from the limit of quantitation to 3.53, 4.09 and 8.66ngg -a, respectively. Aldrin, lindane, heptachlor epoxide and heptachlor were measurable in 10, 20, 22 and 27% of the samples, respectively, at trace concentrations. As indicated in Fig. 3, the highest total (non-DDT) pesticide concentrations in sediments, measured

TABLE 1

DDE DDE DDD DDD DDT DDT

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0.11 _ 0.19 0-05 _+0'09 0.04 _+ 0.05 0.03 _+ 0.02 0"04 + 0"05 0.26 _+0.79 0.21 _+ 0.64 0.26 __+0.45 0.07 _+_0" 10

Total PCBs

0.87

<0.02 0-22 0-03 0.23 <0"02 0.05

0.58

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Mean + 1 S T D (ng/g)

0.08 _ 0'58 + 1.76 + 3.07 + 2.74 + 1.30 + 0.25 + 0'06 +

20 96 56 86 30 71

65 20 27 10 22 77 71 73 48

Median (ng/g)

di-PCBs tri-PCBs tetra-PCBs penta-PCBs hexa-PCBs hepta-PCBs octa-PCBs nona-PCBs

Total DDTs

o-p' p-p' o-p' p,p' o-p' p-p'

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HCB Lindane Heptachlor Aldrin Heptachlor epoxide Alpha-chlordane Trans-nonachlor Dieldrin Mirex

Incidence (%)

< 0-02-189

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<0.02-3.79 <0.02 55.9 <0.02-107 <0.02-134 <0'02-49.5 < 0.02-105

< 0.02-20.5

<0-02-1"66 < 0.02-0-77 < 0-02-0-50 < 0-02-0.16 < 0"02-0-50 < 0.02-8.66 <0-02-3.53 < 0.02-4.09 < 0.02-0.67

Range (ng/g) 0"00

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Total PCBs

0.89

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0-86

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0-58 _+ 1.90 2-57 + 11.0 11.0 + 70.0 13.4 + 86.5 15.6 + 99.0 9.53 + 54.8 2-61 + 14.7 0.43 __+2.92

13 86 42 66 30 44

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Total D D T s

o-p' p-p' o-p' p-p' o-p' p-p'

Total (non-DDT) pesticides

HCB Lindane Heptachlor Aldrin Heptachlor epoxide Alpha-chlordane Trans-nonachlor Dieldrin Mirex

Incidence (%)

<0-02-3 730

<0.02 3 270

<0-02-29.3 <0-02-195 <0.02-319 <0.02-2240 <0-02-25.7 < 0.02-691

< 0.02-89.4

< 0.02-3.62 < 0.02-1-74 < 0.02-1.14 <0.02 2.87 <0-02-3.82 < 0-02-43.5 < 0-02-31.4 <0.02-9.47 <0.02-3-58

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 2 1 22 23 24 26 26 27 28 29 30 31 32 33 34 35 3 6 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51

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Lower Laguna Medre Corpus Christi Corpus Christi Aransas Bay Copeno Bay Mesquite Bay San Antonio Bay San Antonio Bay Espirltu Santo Esplrltu Santo Mategords Bay Mategorda Bay Matagorda Bay Matagorde Bay Galveston Bay Galveston Bay Galveston Bay Galveston Bay Sabine Lake Calcasleu Lake Joseph Harbor Bayou Vermillion Bay East Cote Blanche Atchafalaya Bay Calllou Lake Terrebonne Bay Terrebonne Bay Baratarla Bay Baratarla Bay Breton Sound Breton Sound Lake Borgne Mississippi Sound Mississippi Sound Mississippi Sound Mobile Bay Pensacola Bay Choctawhatchee Bay Choctewhatohee Bay St. Andrew Bay Apalachicola Bay Apalachicola Bay Cedar Key Tampa Bay Tampa Bay Tampa Bay Tampa Bay Charlotte Harbor Naples Bay Rookery Bay Everglades

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Fig. 4. Average total DDT concentrations in sediment samples from Gulf of Mexico sampling sites.

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 2S 27 28 29 30 31 32 33 34 35 36 "J 7 38 3 ~} 4 ¢) 41 42 43 44 45 46 47 48 49 50 51

Lower Legune Medro Corpus Christi Corpus Christi Aranaas Bey Copano Bay Mesquite Bay San Antonio Bay San Antonio Bey Esplrltu Santo Esplrltu Santo Matagorda Bay Matagorda Bay Matagorda Bay Matagorda Bay Galveston Bay Galveston Bay Galveston Bay Galveston Bay Sabine Lake Calcasleu Lake Joseph Harbor Bayou Vermllllon Bay East Cote Blanche Atchafalaya Bay Celllou Lake Terrebonne Bay Terrebonne Bay Baretarla Bay Baratarle Bay Breton Sound Breton Sound Lake Borgne Mississippi Sound Mississippi Sound Mississippi Sound Mobile Bay Pensacola Bay Choctawhatchee Bay Choctawhatchee Bay St. Andrew Bay Apalachlcola Bay Apalachicola Bay Cedar Key Tampa Bay Tampa Bay Tampa Bay Tampa Bay Charlotte Harbor Naples Bay Rookery Bay Everglades

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NOAA's Status and Trends Mussel Watch Program

175

during 1986, were found in samples from Choctawhatchee and Naples Bays, in Florida. Relatively high concentrations were also measured in samples from Tampa, St Andrew, and Roockery Bays, in Florida; Biloxi Bay, in Mississippi; Terrebonne and Barataria Bays, in Louisiana; and Galveston and Matagorda Bays, in Texas. In the first sampling period, sediment samples from Shirk Point (Site No. 39), in Choctawhatchee Bay, contained the highest mean total (non-DDT) pesticide concentration of all the Gulf of Mexico samples (8"59 ng g-1). Sediments from the other Choctawhatchee Bay site, Santa Rosa (Site No. 38), and from St Andrew Bay, Watson Bayou (Site No. 40), also contained relatively elevated concentrations of (nonDDT) pesticides (2-17 and l'76ngg -~, respectively). The second highest concentration detected during 1986 was measured in sediments from Naples Bay (Site No. 49, 5.54 ng g- ~). The highest level in Tampa Bay was found in sediments collected from Cockroach Bay (Site No. 46, 1.83ngg-~). The highest concentrations in the Mississippi River area were measured in sediment samples from Lake Barre (Site No. 26, 1.45 ng g- ~), in Terrebonne Bay, Bayou St Denis (Site No. 28, 1.50ngg- 1), in Barataria Bay, and Biloxi Bay (Site No. 34, 1.46 ngg-1). Yacht Club (Site No. 15) and Todd's Dump (Site No. 16) were the sites with the higher concentrations in Galveston Bay (2.24 and 1"59ng g-1, respectively). Sediment samples collected close to the Lavaca River Mouth (Site No. 11, 2. i 1 ng g - ~), in Matagorda Bay, presented the highest concentrations in a relatively clean area along the southern Texas coast (range = 0"18-0.83 ngg-a). Low concentration sites were also found in Bay Garderne (Site No. 30, 0.19 ng g- ~), in Louisiana, and Dry Bar (Site No. 41, 0.28 ng g-1), in Apalachicola Bay, and Faka Union Bay (Site No. 51, 0.23 ngg-l), in Florida. During the second year, 1987, total (non-DDT) pesticide concentrations ranged from <0.02 to 89.4ngg-~ with a mean concentration of 3"05 + 10.3 ng g- 1 (median = 0.86 ng g- 1). Again, trans-nonachlor and alphachlordane were detected in a large number of samples (70 and 72%) with concentrations varying from < 0-02 to 31"4 ng g - 1 and < 0-02 to 43"5 ng g - ~, respectively. As in the previous year, lindane, aldrin, heptachlor and heptachlor epoxide were measurable in less than 20% of the samples with most of the concentrations close to the detection limit (see distribution frequencies, Table 2). Dieldrin was detected in 43% of the samples, compared with 73% in 1986, with concentrations ranging from <0"02 to 9"47 ng g- 1. HCB and mirex were detected in approximately similar number of samples during 1987 as they were in 1986, with comparable concentrations. The highest total (non-DDT) pesticide concentrations during the second sampling period were mainly detected in sediment samples taken from sites located to the east of the Mississippi River (Fig. 3). Again, sediment samples from Shirk Point, in Choctawhatchee Bay, showed the

176

Josh L. Sericano et al.

highest average concentration (70.1ngg-l). The second highest concentration was found in sediments from St Andrew Bay(13.00 ng g- 1). The highest levels in Tampa Bay were encountered in a sample from Papys Bayou (Site No. 44, 8-66ngg -1) and Mulet Key Bayou (Site No. 47, 7-54 ngg-1). The remaining Tampa Bay sites, Hillsborough (Site No. 45, 2.33 n g g - 1) and Cockroach Bays (0-96ngg-1), presented comparable average concentrations in 1986 and 1987. The highest concentrations along the Louisiana coastline were measured in sediments from Lake Felicity (Site No. 27, 2.04 ng g-~), in Terrebonne Bay, and Oyster Bayou (Site No. 24, 1.77 ng g- 1), in Atchafalaya Bay. In Texas, sediments from Yacht Club, in Galveston Bay had similar concentrations to those found during 1986 (2"47ngg-1). The lowest total (non-DDT) pesticide concentrations in sediments were reported for samples taken from the Matagorda Bay area (Sites Nos 11 to 14, range 0"22 to 0.51 ng g- 1). Low concentrations were also found in samples from Blue Buck Point (Site No. 19, 0.22 n g g - 1), in Sabine Lake, Caillou Lake (Site No. 25, 0.64 ng g-1), Pass Christian (Site No. 33, 0"51ngg-1), in the Mississippi Sound, Indian Bayou (Site No. 37, 0.45 n g g - 1), in Pensacola Bay, and Cat Point Bar (Site No. 42, 0.39 n g g - 1), in Apalachicola Bay. The second Apalachicola Bay site, Dry Bar, one of the low concentration sites in 1986, had the sixth highest average concentration during 1987 (3.46ngg- 1). Total DDTs, i.e. the sum of o-p' DDE +p-p' DDE + o-p' DDD + p-p' DDD + o-p' DDT +p-p' DDT, were the most abundant chlorinated pesticides in sediments. DDT and/or its metabolites were detected in 95 and 88% of the samples during the first and second year, respectively. In 1986, total DDT concentrations ranged from < 0.02 to 454 ng g-1 with a mean value of 6"18 + 37"3 n g g - 1(mediail = 0-87 n g g - 1). Figure 4 summarizes the average total DDT concentrations measured in sediment samples during 1986 and 1987. The highest concentrations were mainly encountered in sites from Mobile Bay, in Alabama, to St Andrew Bay, in Florida, i.e. sites No. 36 through No. 40. Within these sites, Shirk Point, in Choctawhatchee Bay, was readily distinguishable with an average concentration of 175 ngg 1 The concentration range for the remaining sites within that area was 8"65 to 18.0ngg -1 Sediment samples collected from Hillsborough Bay (9"49ngg-1), in Tampa Bay, also had high average total DDT concentration. Isolated 'hot spots' were also found along Louisiana and Texas coasts. In Texas, sediments with the highest average DDT concentrations were found at two Matagorda Bay sites, Lavaca River Mouth (13.3 ng g- ~) and Tres Palacios Bay (Site No. 13, 25.7 ngg-1). In Louisiana, the highest concentrations were found in sediment samples from Oyster Bayou (2-64ngg-1), in Atchafalaya Bay, and East Cote Blanche (Site No. 23, 3-10ngg- 1).

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177

During 1987, total D D T concentrations in sediments averaged 32.0 ___ 275 ng g- 1 (median = 0.89 ng g- 1) with a range from < 0.02 to 3270 ng g- 1. Individually, DDT and its metabolites were detected in similar number of samples during 1987 as they were in 1986. In general, the distribution of sites with the highest average total DDT concentrations during 1987 is very similar to that encountered during the previous sampling year. Again, the area from Biloxi to Apalachicola Bays, had the highest DDT concentrations in sediments from the Gulf of Mexico. Within this area, Shirk Point had the greatest DDT concentration (1460ngg-1). The average concentrations measured at the remaining sites within this area ranged from 2.71 ng g- 1, in sediments from Pascagoula Bay (Site No. 35) to 59.3 ng g- 1, in samples from Watson Bayou, in St Andrew Bay. Sediment samples from two Tampa Bay sites, Papys Bayou (20"7 ng g- 1) and Hillsborough Bay (7"42 ng g- 1) also contained relatively elevated concentrations of DDT and its metabolites. To the west of the Mississippi River, the highest average concentrations were detected in samples from Oyster Bayou (5.63 ng g-1), in Atchafalaya Bay, and Gallinipper Point (Site No. 12, 2.61ngg -1) and Tres Palacios Bay (3-29 ng g-1), in Matagorda Bay. In general, the lowest average total DDT concentrations in sediments were measured in samples collected from sites located along the southern Texas shoreline (range = 0" 124)-30 ng g- 1). PCBs proved to be ubiquitous contaminants in sediments collected for this study. Average total PCB concentrations were 9.84+ 20.6ngg -1 (median = 4"20 ng g- 1; range = < 0.02-189 ng g- 1) and 55.7 ___328 ng g- 1 (median = 5.40 ng g- 1; range = < 0-02-3730 ng g- 1) for the first and second sampling year, respectively. Mean total PCB concentrations, for 1986 and 1987, are presented in Fig. 5. During 1986, sediments with the highest PCB concentrations were found at a site near the Lavaca River Mouth (66.7 ng g- 1), in Matagorda Bay. Sediments from Florida, specifically from Choctawhatchee (24.3 and 50.7ngg -1 at sites No. 38 and No. 39, respectively), St Andrew (39.3 ng g- 1), Tampa (24.7 ng g- 1 at Site No. 45), and Naples Bays (26-6 ng g-1) also had high PCB concentrations. During 1987, important increases in concentration were detected in sites to the east of the Mississippi River, particularly at Shirk Point (196 up from 50.8ngg-1), in Choctawhatchee Bay, Watson Bayou (1840 up from 39.3 n g g - 1), in St Andrew Bay, and Papys Bayou (275 up from 0.70 ng g- 1), in Tampa Bay. Increases were also observed in sites like Yacht Club (39" 1 up from 11"0 ng g- 1), in Galveston Bay, Biloxi Bay (50.7 up from 6"83 ng g- 1), Mobile Bay (Site No. 36, 36.6 up from 8-20ngg-1), and Hillsborough Bay (62-1 up from 24.7ng g-~), in Tampa Bay. However, the apparent increases observed during the second year at the last four sites might be a consequence of the very large variability observed within stations at each of these sites. This may also be the reason for the decrease in concentrations observed

178

JosO L. Sericano et al.

between 1986 and 1987 at Lavaca River Mouth (1.87 down from 66.7 n g g - 1), in Matagorda Bay.

Oyster analyses The same suite of chlorinated hydrocarbons listed for sediments were analyzed in 291 samples, each consisting of 20 pooled oysters, collected at 49 and 48 sites during 1986 and 1987, respectively. No oyster samples were collected from Bill Days Reef(Site No. 10) and East Cote Blanche (Site No. 23)during 1986 and 1987. In 1987, no live oysters were found at one of the Corpus Christi sites, Ingleside Cove (Site No. 3). Percent incidence, mean and median concentrations, range and distribution frequency for each analyte are presented in Tables 3 and 4 as well as concentrations of total (non-DDT) pesticides, DDTs and PCBs. Average concentrations in oyster tissues, plus 1 standard deviation, are shown in Figs 6 to 8. Concentrations of chlorinated hydrocarbons in oysters were, in general, higher than those detected in sediment samples from the same stations. During 1986, total (non-DDT) pesticide concentration in oysters ranged from 3"26 to 2 3 2 n g g - 1 with an average value of 35"8 + 38"3 ngg-1 (median = 23.0ngg-1). Alpha-chlordane and t r a n s - n o n a c h l o r were detected in every sample with concentrations ranging over two orders of magnitude. Dieldrin was detected in all but one sample with a similar concentration range. Lindane was more frequently encountered in oyster tissues than in sediments. On the other hand, no large differences were observed in the occurrence of heptachlor and mirex when tissue and sediment were compared. However, the average concentrations of these compounds were 10 and 20 times higher, respectively, in oysters than in sediments. HCB was detected in a smaller percentage of oyster samples than in sediment samples. Very similar concentrations and occurrences of the individual (non-DDT) pesticides in oyster samples were observed during the second sampling year when compared to the first year. Total (non-DDT) pesticide concentrations in oysters ranged from 3.50 to 623 ng g- 1 with an average value of 39.4 + 64-9 n g g - 1 (median = 22-0ng g- 1). Figure 6 summarizes the average (non-DDT) pesticide concentrations in oyster samples from the northern Gulf of Mexico measured during 1986 and 1987. In general, the distributions of sites having the highest and lowest mean concentrations were very similar during both sampling years. In 1986, the highest concentration was measured at the Yacht Club site (168 ng g-1), in Galveston Bay; a similar concentration was found for the second year (191 ngg-1). In 1987, the highest concentration reported in oyster tissues was for bivalve samples collected at Shirk Point (306 ng g-1, an increase from 64"5ngg-l), in Choctawhatchee Bay. Other sites having high

173 +_ 373

78.6

45.2 _ 58.t

1.60 __+7.29 17.3 + 17.4 5.75 ___12"5 17.6 + 27.7 1.14 + 2.61 1"77 + 4'11

35.8 + 38-3

0"32 _+ 0-26 1.04 + 0-99 0.51 + 0.69 0.28 __+0.13 2'71 _ 3.31 10.9 ___14.4 10.0 ___13-8 8.64 + 9.61 !.40 + 2'61

Total PCBs

26.5

<0.25 11.1 2.13 8.62 <0.25 0"64

23.0

<0"25 0.74 <0-25 <0.25 1.87 5.23 4.58 5-70 < 0.25

0-35 + 1.24 8'26 +__19'5 38-3 _ 80-9 77.5 + 201 41.7 + 72-2 5.86 + 9.34 0-43 + 0-98 0-41 __+1.64

39 100 89 91 30 68

16 82 37 9 86 t00 100 99 49

Mean +_ 1 S T D (ng/g)

di-PCBs tri-PCBs tetra-PCBs penta-PCBs hexa~PCBs hepta-PCBs octa-PCBs nona-PCBs

Total D D T s

DDE DDE DDD DDD o-e I D D T p-p' D D T

o-p' p-p' o-p' p-p'

Total (non-DDT) pesticides

HCB Lindane Heptachlor Aldrin Heptachlor epoxide Alpha-chlordane Trans-nonachlor Dieldrin Mirex

Median (ng/g)

10-0-4020

3-69-395

<0.25-64.0 1.64-131 <0.25 120 <0-25-159 <0.25-22.2 <0"25~38"6

3.26-232

<0'25-1"93 < 0.25-5.62 <0.254.62 <0.25-1.40 < 0-25-24-5 0-91-96-3 0-60-71.9 0.25-52.2 < 0.25-15-8

Range (ng/g) 0.00

11 2 6 30

11 9 70 32

12 47 29 8 12 1 1 3 22

~

23

0"25

61

1 51

84 18 63 91 14

~

1"00

14 43 65 46 23 34

4 35 8 1 70 72 76 71 24

--*

I0"0

~

2 46 12 40 1 4

4 27 23 25 3

Percent distribution 100

1 1 3

--*

(ng/g)

TABLE 3 C o n c e n t r a t i o n s (ng/g, d r y w e i g h t ) a n d D i s t r i b u t i o n F r e q u e n c i e s ( % ) in t h e G u l f o f M e x i c o O y s t e r s , 1986

Incidence (%)

Chlorinated llydrocarbon

:~

.,~

~' ~,

e~

,,.a:~ :x ~"

134 _+ 242

62-3

Total PCBs

+ 4.70 + 11.9 __+54'8 + 151 + 48.5 _ 7-10 + 2.54 + 1.19

67.9 + 298 1.62 7.59 25.7 66.2 26.8 4.88 0.98 0.29

26.1

1.33 _+ 7.84 29-4_ 100 9.98 + 81.3 25-0 ___111 0.68 ___1.79 1.49 + 2.95

39.4 _+ 64.9

0"36 + 0-45 1"74 + 1-80 0.54 _+ 0-99 0.34 _+_0"56 3.30 _+_3.93 14.1 _+ 29.0 11.6 _+ 27.7 6.08 + 7.31 1-38 _+ 2.77

Mean + 1 S T D (rig~g)

di-PCBs tri-PCBs tetra-PCBs penta-PCBs hexa PCBs hepta-PCBs octa-PCBs nona-PCBs

Total D D T s

24 100 73 98 17 36

<0.25 12.5 1.19 8.02 <0.25 < 0'25

DDE DDE DDD DDD DDT DDT

o-p' p-p' o-p' p-p' o-p' p-p'

<0"25 1-20 < 0-25 < 0.25 2.45 6.42 4.78 3.71 <0.25 22.0

14 80 23 9 98 100 99 95 38

Total (non-DDT) pesticides

HCB Lindane Heptaehlor Aldrin Heptachlor epoxide Alpha-chlordane Trans-nonachlor Dieldrin Mirex

Median (rig~g)

3.60-1 740

3.02-3 570

<0.25-85.7 0.57-1 170 <0.25-975 <0-25-1 310 <0'25 18.9 < 0.25-25.6

3.50-623

0"25~4"33 0.25-9.06 0.25-7'04 0.25-6.66 0.25-27.3 0.65-292 < 0.25-289 < 0.25-51.6 <0.25-16.1

< < < < <

Range rag~g) 0"00

27 2 83 64

76

1 5 62

86 20 77 91 2

~

0"25

15 5 16 5 3 8

10 24 14 7 11 1 5 I0 13

--*

1"00

8 38 50 53 13 26

4 56 9 2 82 71 73 68 22

---}

10"0

Percent distribution

1 55 6 37 1 2

5 27 20 17 3

---}

100

2 1 3

1 1

---,

(ng/g)

TABLE 4 C o n c e n t r a t i o n s (ng/g, d r y w e i g h t ) a n d D i s t r i b u t i o n F r e q u e n c i e s ( % ) in t h e G u l f o f M e x i c o O y s t e r s , 1987

bwidence (%)

Chlorinated Hydrocarbon

~.

~"

NOAA's Status and Trends Mussel Watch Program

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 60 5 1

Lower Laguna Msdre Corpus Chrlstl Corpus Chrlstl Aransss Bay Copano Bay Mesquite Bay San Antonio Bay San Antonio Bay Esplrltu Santo Esplrltu Santo Mategorda Bay Matagords Bay Matsgorda Bay Matagorda Bay Galveston Bay Galveston Bay Galveston Bay Galveston Bay Sabine Lake Catcesleu Lake Joseph Harbor Bayou Vermiltlon Bay East Cote Blanche Atchafalaya Bay Calllou Lake Terrebonne Bay Terrebonne Say Barataria Bay Baratarla Bay Breton Sound Breton Sound Lake Borgne Mississippi Sound Mississippi Sound Mississippi Sound Mobile Bay Pensacola Bay Choctawhatchee Bay Choctawhatchee Bay St. Andrew Bay Apalachicola Bay Apalachlcola Bay Cedar Key Tampa Bay Tampa Bay Tampa Bay Tampa Bay Charlotte Harbor Naples Bay Rookery Bay Everglades

~

181

•

1986

•

1987

m., ~

IlL

m B

m

~

IB

~lllmmlmlllll~~,

liP" 3064 L

~

l

~

i/immmmllmlmb=B

II~ 0

50 Total

100

150

200

2 O

(non-DDT) Pesticides in Oysters (ng/g dry weight)

Fig. 6. Average total (non-DDT) pesticide concentrations in oyster samples from Gull" of Mexico sampling sites,

182

Josk L. Sericano et al.

I 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 2 6 27 28 29 30 31 32 33 34 35 3 6 37 38 3 9 40 41 42 43 44 45 4 6 4 7 4 3 4 ~ 50 5 1

Lower Laguns Msdre ~ ; ' Corpus Chrlsfl ~ Corpus Chrlstl Arsnsas Bay Copano Bay Mesquite Bay BI~ San Antonio Bay ~IL San Antonio Bay Espirltu Santo Espiritu Santo Matsgorda Bay Matagorda Bay Matagords Bay ~ Matagorda Bay Galveston Bay Galveston Bay Galveston Bay Galveston Bay Sabine Lake Calcasleu Lake Joseph Harbor Bayou Vermillion Bay East Cote Blanche Atchafalaya Bay ~ : : Caillou Lake Terrebonne Bay I~ Terrebonne Bay IL Baratsrla Bay Barataria Bay Breton Sound Breton Sound ~ B l ~ Lake Borgne Mlsslsslppl Sound Mississippi Sound Mississippi Sound Mobile Bay Pensacola Bay Choctawhatchee Bay Choctawhatchee Bay St. Andrew Bay Apalachlcola Bay Apalachlcola Bay Cedar Key Tampa Bay Tampa Bay Tampa Bay Tampa Bay Charlotte Harbor ~ B ~ Naples Bay ~lBm==zl~--, Rookery Bay J i Everglades 0

50

1986

•

1987

"

~

l 100

Total

Fig. 7.

•

]320~"

l 150

200

250

300

350

DDE+DDD+DDT in Oysters (ng/g dry weight)

Average total D D T concentrations in oyster samples from Gulf of Mexico sampling sites.

NOAA's Status and Trends Mussel Watch Program

1 2 3 4 S 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51

Lower Lsguna Msdre Corpus Christi Corpus Christi Aransas Bay Copano Bay Mesquite Bay San Antonio Bay Sen Antonio Bay Esplrltu Santo Esplrltu Santo Matagords Bay Matagorde Bay Mstagorda Bay Matagorda Bay Galveston Bay Galveston Bay Galveston Bay Galveston Bay Sabine Lake Cslcasteu Lake Joseph Harbor Bayou Vermllllon Bay East Cote Blanche Atchafalaya Bay Calllou Lake Terrebonne Bay Terrebonne Bay Baratarla Bay Baratarla Bay Breton Sound Breton Sound Lake Borgne Mississippi Sound Mississippi Sound Mississippi Sound Mobile Bay Pensacola Bay Choctawhatchee Bay Choctawhatchee Bay St. Andrew Bay Apalachicola Bay Apalachlcola Bay Cedar Key Tampa Bay Tampa Bay Tampa Bay Tampa Bay Charlotte Harbor Naples Bay Rookery Bay Everglades

~ ~. p ~ B

183

•

1986

m

1987

~_.

19so..

~

/

i F

w p

P

E-0

300

600

900

1200

1500

Total PCBs in Oysters (ng/g dry weight)

Fig. 8.

Average total PCB concentrations in oyster samples from Gulf of Mexico sampling sites.

184

Josh L. Sericano et al.

concentrations during 1986 and 1987, respectively, were Todd's Dump (42.6 and 87-3 ng g- 1), in Galveston Bay, Biloxi Bay (134 and 113 ng g- 1), Watson Bayou (105 and 73.6ngg-1), in St Andrew Bay, Papys Bayou (79.6 and 116 ngg-1) and Cockroach Bay (89.3 and 56-5 ng g-1), in Tampa Bay, and Naples Bay (118 and 54.4ngg-1). As in sediments, DDT and its metabolites were the most abundant chlorinated pesticides in oyster samples. Total DDTs ranged from 3"69 to 395ngg -1 and 3-02 to 3570ngg -~ with mean concentrations of 45.2 + 58"1 ng g- ~ (median = 26.5 ng g- 1) and 67-9 + 298 ng g- 1 (median = 26.1 ngg-1) for the first and second sampling year, respectively. Average total DDT concentrations in oyster samples are presented in Fig. 7. As in (non-DDT) pesticides, the distribution of DDT and its metabolites in oyster samples from the northern Gulf of Mexico was very similar during both sampling years. Highest average concentrations were encountered in samples from Matagorda and Galveston Bays, in Texas, Vermilion and Atchafalaya Bays, in Louisiana, Biloxi Bay, in Mississippi, Mobile Bay, in Alabama, and Choctawhatchee, St Andrew and Tampa Bays, in Florida. In 1986 and 1987, samples from Shirk Point, in Choctawhatchee Bay, presented the highest total DDT concentrations of all the Gulf of Mexico oyster samples collected during this study (303 and 1320ngg -1, respectively). During the same period, the second and third highest concentrations were measured in samples from Watson Bayou (192 and 163 ngg-1), in St Andrew Bay, and Cedar Point Reef (153 and 156ngg-1), in Mobile Bay, respectively. West of the Mississippi River, the highest levels were found in samples from Yacht Club (151 and l l 5 n g g - ~ ) , in Galveston Bay, Tres Palacios Bay (94-0 and 87-3 ng g- 1), in Matagorda Bay, Southwest Pass (Site No. 22, 56.2 and 70.5 ng g- ~), in Vermilion Bay, and Oyster Bayou (49.4 and 55"9 ng g-1), in Atchafalaya Bay. PCB congeners were detected in all the oyster samples collected during 1986 and 1987 with average concentrations of 173 + 373ngg -~ (median = 78"6ngg-~; range = 10-0-4020ngg -1) and 134 + 242ngg -1 (median = 62.3 ng g- 1; range = 3.60-1740 ng g- 1), respectively. During 1986 and 1987, the highest PCB concentrations, 1950 and l l 9 0 n g g -1, respectively, were detected at Galveston Bay, Yacht Club (Fig. 8). High PCB concentrations were also recurrent in samples from sites along the northern Florida coast, particularly from Indian Bayou (626 and 663 ng g - 1), in Pensacola Bay, and Watson Bayou (891 and 542 ng g- 1), in St Andrew Bay. Samples from Shirk Point, in Choctawhatchee Bay, had the second highest concentration during 1987 (776ngg-~); however, the variability among the stations at this site was large. Oysters from a second Choctawhatchee Bay site, Santa Rosa, had one of the lowest concentrations during both sampling periods (37.1 and 25-0ngg -1 in 1986 and 1987,

NOAA's Status and Trends Mussel Watch Program

185

respectively). With the exception of the above mentioned Galveston Bay site, average PCB concentrations in oysters were generally low in sites located to the west of the Mississippi River.

DISCUSSION In the previous section, the average concentrations of total (non-DDT) pesticides, DDT and its metabolites and PCB congeners in sediment and oysters samples from the northern Gulf of Mexico were described. In general, the individual (non-DDT) pesticides present in highest abundance in sediment samples were also found in highest concentrations in oyster tissues; however, when both types of sample are compared, oysters had concentrations 10 to 30 times higher than sediments. In both matrices, transnonachlor, alpha-chlordane and dieldrin represented the major fractions of the total concentrations. On average, these compounds counted for 70-75% and 80-85% of the total (non-DDT) pesticides measured in sediments and oysters, respectively. Concentrations of alpha-chlordane and transnonachlor had, as expected, a high covariability since both compounds are components of technical chlordane. Aldrin was rarely found during this study, less than 20% in sediments and 10% in oysters, possibly because it may be degraded to dieldrin in the environment. The epoxidation of heptachlor to heptachlor epoxide, a form that is almost exclusively found in organisms due to enzymatic conversion, is most likely responsible for the significant increase in the incidence of heptachlor epoxide observed in oysters compared to sediments. Lindane was detected with higher frequency in oyster than in sediment samples during both sampling periods. From reported sorption coefficients (Karickhoff, 1981), sorption of lindane to sediments does not appear to be, comparatively, a significant process. Since most of the lindane remains in the water column, it may be more readily available to filter feeders. Despite the DDT ban in the early 1970s, this compound and/or its metabolites are still present, in significant concentrations, in nearshore sediments of the Gulf of Mexico. Approximately 70%, in 1986, to 80%, in 1987, of the total DDT load encountered in sediments corresponded to the sum of (o-if+p-if) DDE+(o-p'+p-p') DDD. The fact that DDT metabolites are dominant indicates an active degradation of DDT in the marine environment and/or inputs of already degraded DDT to coastal areas. DDT can be degraded to D D D by microorganisms (Patil et al., 1972; Gerlach, 1981) or to D D E via dehydrochlorination produced by decomposition reactions taking place biotically (Fries, 1972; Walker, 1975) and abiotically (Crosby, 1969). Phytoplankton can degrade p-p' DDT to p-p'

Josb L. Sericano et al.

186

D D D (Addison, 1976). Woodwell et al. (1971) estimated a half-life for DDT, under environmental conditions, of up to 20 years. DDE, the major hydrolysis product of DDT, appears to be more persistent in the aquatic environment than its parent compound (Wolfe et al., 1977). In both sampling periods, composition of sedimentary DDTs was dominated by p-p' isomers. The proportion ofp-p' isomers found in sediments, 75 and 85% for 1986 and 1987, respectively, are similar to the percentage ofp-p' isomers reported for technical grade DDT (Melnikov, 1971). This suggests that the p-p' and o-p' isomers are converted and/or degraded at similar rates in the marine environment. DDT, as combined isomers, accounted only for 6%, in 1986, and 3%, in 1987, of the total DDT burden detected in oysters. The overall average percentages of DDT and its metabolites were different in oysters and sediments (Fig. 9). While the mean percentages of D D D were similar in oysters (51-6%) and sediments (64.0°/0, the proportion of D D E was significantly higher in oysters (43-9%) than in sediments (14-2%). The opposite is observed when D D T was considered; the percentage in oysters (4"5%) was significantly lower than the percentage calculated for sediments (21-8%). These differences may be related to uptake, metabolism and/or depuration mechanisms for D D T compounds in oysters. Such a decrease in D D T relative to DDE has also been observed in other marine organisms (Butler & Schutzmann, 1978). About 80% of the total DDT load in oysters corresponded to p-p' isomers; a percentage that is similar to the proportion of the p-p' isomers found in sediments. The average composition of PCBs (mean of both years), was different in sediments compared to oysters (Fig. 10). In sediments, PCB congeners were nearly equally dominated by hexa- and pentachlorobiphenyls and, to a 8O

60

<

Z ~

SEDIMENTS

[]

OYSTERS

~._

/

40

r~

20

[]

e,i ~

I

0

DDE DDD DDT Fig. 9. Averagecompositionof DDT and its metabolitesin Gulf of Mexicosedimentsand oysters.

NOAA's Status and Trends Mussel Watch Program

187

60

50

~

~

•

SEDIMENTS

[]

OYSTERS

40

30

~

20

lO

'~

~ 4~

0

Fig. 10. Averagecompositionof PCB homologsin Gulf of Mexico sedimentsand oysters. lesser extent, by tetra- and heptachlorobiphenyls. They represented more than 89% of the total sedimentary PCB load. In oysters, PCBs were largely dominated by pentachlorobiphenyls (46-8%), with some hexa- and tetrachlorobiphenyls (22-3 and 21-0%) and were almost depleted in di-, octaand nonachlorobiphenyl. The same general pattern was found in organisms collected from PCB-contaminated areas (Shaw & Connell, 1982; Duinker et al., 1983; Boon et al., 1985). The average PCB composition in oyster was similar to technical Aroclor 1254, while the average distribution of PCB homologs in sediments was similar to a mixture of Aroclor 1254 + Aroclor 1260. Competitive partition between aqueous and nonpolar phases, e.g. lipids, as well as stereochemistry appear to be significant factors influencing bioaccumulation (Jan & Josipovic, 1978; Tulp & Hutzinger, 1978; Matsuo, 1980; Shaw & Connell, 1980, 1982, 1984; Samuelian & O'Connor, 1985). In general, maximum PCB uptake by organisms is observed with isomers having five to seven chlorine atoms. Congeners with less chlorines have higher water solubilities and, as a consequence, less favorable partition coefficients. In contrast, isomers in the higher homolog groups have unfavorable steric configurations (Shaw & Connell, 1984). This results in some differences when the dominant PCB congeners in oysters and sediments are compared (Fig. 11). Dominant PCBs in oysters were 118/108/149(5/5/6) > 138(6) > 105/132(5/6) > 110/77(5/4) > 41/64(4/4) > 101(5) while in sediments the order was 153(6)> 110/77(5/4)> 138(6)> 118/108/149(5/5/6)> 170(7) (the '/' indicates co-eluting congeners; the numbers given in parentheses indicate the level of chlorination). On average, these compounds were individually detected in concentrations higher than

Jos6 L. Sericano et al.

188

5% o f the total PCB load in both sediment and oyster samples. Combined, they accounted for 43.9 and 36,7% of the total PCBs in oysters and sediments, respectively. Approximately the same dominant PCB isomers were reported in recent studies. For example: dominant PCB congeners in benthic invertebrates (i.e. Macoma balthica and Arenicala marina) and sediments from the Dutch 10 •

SEDIMENTS

8

~2

~

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ISOMERS

Fig. 11.

Average composition of individual PCB isomers in Gulf of Mexico sediments and oysters.

NOAA's Status and Trends Mussel Watch Program

189

Wadden Sea were 101, 118, 138, 149, 153, 180 and 187, with 118 being the congener usually having the highest concentration, and 15, 18, 28, 118, 138, 153 and 187, respectively (Duinker et al., 1983). Dominant PCB congeners in benthic polychaetes (Nephtys spp.) from the southern North Sea were 118, 138, 149, 153 and 180 while in sediments the highest concentrations corresponded to 15, 18, 118, 138, 153 (Boon et al., 1985). Recently, Niimi & Oliver (1989) reported that the ten most common congeners detected in trout and salmon from Lake Ontario were 101, 84, 118, 110, 87/97, 153, 138, 149 and 180. Therefore, it appears that the specific congeners being analyzed in the Status and Trends Mussel Watch Program overlap well with those reported in organisms and sediments from other locations. In order to examine correlations of chlorinated hydrocarbon contents in oysters and sediments, the overall average concentrations of total (nonDDT) pesticides, DDT and its metabolites and PCB congeners, i.e. both years combined, were analyzed by regression analysis using Spearman's rank correlation. Chlorinated hydrocarbon concentrations in oysters were significantly correlated ( P < 0 . 0 1 ) with concentrations in sediments; although only about 12, 37 and 10% of the variability observed in total (nonDDT) pesticide, D D T and PCB concentrations in oysters, respectively, can be explained in terms of pollutant load encountered in sediments. The comparison of this present large data set to earlier results based on fewer samples presents some problems. First, such comparisons are complicated by the substantial changes that have been made in analytical methods in recent years. Second, in large environmental data sets expanding over a large area, it is not uncommon to find extremely high values that strongly bias the mean. These values, however, will not affect the median as much as the mean. The use of the median to show central tendency of a data set and to compare different data sets seems to be a more adequate approach. Unfortunately, this parameter is usually not reported in previous studies, for instance those listed on Tables 5 and 6. Since those studies were restricted to relatively small geographical areas, it is less likely to find values that might be considered outliers. Thus, in small data sets the mean and median can be assumed to be nearly equal. With this assumption, and past methodology limitations, in mind, it is worthwhile to compare the present data to some of the available sets of data for the Gulf of Mexico. The average concentrations of individual (non-DDT) pesticides encountered in sediment and oyster samples during the first two years of the Status and Trends Mussel Watch Program were, in general, within the range of average concentrations previously reported for the Gulf of Mexico coastal areas. For example, the mean concentrations reported for dieldrin in sediments (0.26 and 0.36 ng g- 1 for 1986 and 1987, respectively) were comparable to the values reported by Giam et al. (1978b) (0"1 ng g-1) and Elder & Mattraw (1984) (<0-1 ng g-1).

Clams Sediments Sediments Sediments

Sediments Sediments Sediments

Apalachicola River (F1)a

Mississippi Delta (La) Gulf of Mexico Coast Nueces Estuarie (Tx)

Galveston Bay (Tx) Apalachicola Bay (FI) Apalaehicola River (F1)~

median concentrations. (nd) not detected.

37 27 9

Molluscs, fish Fish, shrimp Oysters

-56 12

--

9

7 9 46 29 18 62 30 43 23 5 27 24

n

Fish Fish, crab, oysters Fish, shrimp Plankton Fish Crabs Oysters Clams Shrimp Plankton Fish (mesopelagic) Fish

Sample

Escambia Bay (FI) Aransas Bay (Tx) Gulf of Mexico G u l f of Mexico G u l f of Mexico San Antonio Bay (Tx) San Antonio Bay (Tx) San Antonio Bay (Tx) San Antonio Bay (Tx) Mississippi Delta (La) Mississippi Delta (La) Estuaries of Texas, Mississippi, Louisiana, Alabama & Florida St Louis & Mississippi Bays (Ms) Gulf of Mexico Mexican Coastal Lagoons

Location

1.1 3.0 1.0

18.7 2 4.7

21

-25 55

84 25 203

66 95 33 ----

11

PCBs (ng/g)

0-2 3.3 1-7

4-2 1.3 1.5

29

10 15

-49 62 7 19 16 25 20 2 1 10 18.2

DDTs (ng/g)

<0.1

0.1

----

2

--0.9

-9 ---2.1 8.9 2.9 1.8 12 -15.2

Dieldrin (ng/g)

H C B (0-11) Lindane (0-03) Chlordane (0.77) HCB (0-49) -Chlordane ( < 11

---

-----Toxaphene (200) Ethyl parathion (75) Methyl parathion (47) Mirex (139) -Chlordane (nd) Endrin (nd) Chlordane (21 ) Hep. Epoxide (0.3)

------

Others (ng/g)

Giam et al. (1978b) Livingston et al. (1978) Elder & Mattraw (1984)

Giam et al. (1978b) Giam et al. (1978b) Giam et al., (1978b)

Elder & Mattraw (1984)

De La Cruz & Lue (1978) Giam et al. (1978a) Rosales et al. (1979)

Duke et al. (1970) Fay & Newland (1972) Giam et al. (1972) Giam et al. (1973) Giam et al. (1974) Petrocelli et al. (1974) Petrocelli et al. (1974) Petrocelli et al. (1974) Petrocelli et al. (1974) Baird et al. (1975) Baird et al. (1975) Butler & Schutzmann (1978)

Reference

TABLE 5 A v e r a g e C o n c e n t r a t i o n s o f C h l o r i n a t e d H y d r o c a r b o n R e s i d u e s in B i o t a a n d S e d i m e n t s f r o m t h e G u l f o f M e x i c o a n d A d j a c e n t E s t u a r i e s a n d B a y s

¢~2.

~" .~

N O A A ' s Status and Trends Mussel Watch Program

191

TABLE 6 Average Chlorinated Hydrocarbon Concentrations (and Ranges) in Oysters and Sediments from the G u l f o f Mexico. National Programs Year

n

DDTs in oysters (ng/g)

1965

58

257+542

a

PCBs in oysters (ng/g)

DDTs in sediments (ng/g)

PCBs in sediments (ng/g)

Reference

--

--

--

--

--

--

--

--

B u t l e r (19731

--

--

--

Butler (1973)

--

--

--

B u t l e r (1973)

--

--

--

B u t l e r (1973)

--

--

--

Butler (1973)

--

--

--

Butler (1973)

71"2 + 104

--

--

Farrington

Butler (1973)

( < 3 3 ~ , 730) 1966

152

346_+484 a

Butler(19731

( < 3 3 - 3 890) 1967

155

292 + 428 a ( < 3 3 - 2 790)

1968

136

4 5 0 + _ 575 a ( < 33-6 490)

1969

142

284 + 497 a ( < 3 3 - 3 530)

1970

144

234+_301 a ( < 3 3 - 2 200)

1971

140

217 +_ 4 9 5 a ( < 3 3 - 2 840)

1972

60

162_+206 a ( < 33-933)

1976

9

18.7 + 12.4 b (6.0-42.0)

1977 1984

9

( < 20-336)

11-0 +_ 9"10 b

83"0_+ 87-8

(2'8-28.0)

(16-297)

11

a recalculated on dry b calculated as DDE.

--

et al.

(1982) --

--

Farrington

et al.

(t982) 1.83 + 1-89

23.0

(0-1-7.0)

(nd-34.0)

NOAA

((1987)

weight basis, see text.

The range of mean concentrations previously reported for HCB in sediments (0.11 to 0.49 ng g-l, Giam et al., 1978b) overlaps well the average concentrations encountered during 1986 (0.11 ng g-l) and 1987 (0.25ngg-1). Lindane (0"05 and 0"07ngg -1) and chlordane (0"26 and 1-18ngg-1) sediment concentrations reported in 1986 and 1987, respectively, were comparable to the lindane concentration reported in 1978 (0.03 ngg-1, Giam et al., 1978b) and chlordane concentrations reported in 1978 (0.77ngg -1, Giam et al., 1978b) and 1984 ( < l n g g -1, Elder & Mattraw, 1984). Average DDT concentrations in sediments were highly biased by the concentrations encountered in samples from Shirk Point, in Choctawhatchee Bay, particularly during the second sampling year (175 and 1460ng g-~, respectively). However, the median concentrations (0.87

192

Josh L. Sericano et al.

and 0.89 ng g-1, for 1986 and 1987, respectively) were within the range of mean DDT concentrations reported earlier for the Gulf of Mexico coastal sediments (0.2 to 4.2 ng g- 1) and comparable to the average concentrations reported in the NOAA's Benthic Surveillance Study (1.83 ng g-1, NOAA, 1987). The same situation can be observed with the oyster data. For example, the average dieldrin concentrations in oysters (8.64 and 6"08 ng g- 1 for 1986 and 1987, respectively) were within the range of mean concentrations reported in biota from the Gulf of Mexico (0.9 to 15-2 ng g- 1). Median DDT concentrations (26-5 and 26"1 ng g- 1 for 1986 and 1987, respectively), were in the range of average concentrations encountered in organisms between 1978 and 1984 (1 to 62 ng g- 1) and were similar to the levels reported in previous works involving oysters in the Gulf of Mexico (49 ng g- 1 Fay & Newland, 1972; 25 n g g - 1, Petrocelli et al., 1974; 15 n g g - 1, Rosales et al., 1979; 11.0 and 18"7ngg -1, Farrington et al., 1982). As in the case of total DDTs, average total PCB concentrations in sediments and oysters were strongly biassed by the concentrations encountered at a few sites (Figs 5 and 8). However, the median concentrations measured in sediments (4.20 and 5.40ngg -~) and oysters (78"6 and 62.3 ngg -~) during 1986 and 1987, respectively, were comparable to the average concentrations previously reported for sediments (1-23 ng g- 1) and oysters (55-83 ng g- 1) in the Gulf of Mexico (Tables 5 and 6). The only Gulf of Mexico coastal-wide data set for DDT and its metabolites in oysters to which the present study can be directly compared is the data of Butler (1973). Butler reported the concentrations of DDE, D D D and D D T in 8095 shellfish samples, mostly Crassostrea virginica, Crassostrea gigas and Mercenaria mercenaria, from estuarine and coastal areas of the US between 1965 and 1972. Over 1500 of these samples, collected at 34 sites, were from the Gulf of Mexico. Only 14 of these sites were sampled at least 7 of the 8 years of the study. The average total DDT concentrations corresponding to those sites from 1965 to 1972 are shown in Table 6. To compare Butler's findings to the present data set, his concentrations were recalculated to ng g-~ dry weight of tissue assuming 85% wet weight. Butler's 1965-72 total D D T concentrations for the Gulf of Mexico peaked in 1968 and has been declining markedly since 1969. Although the ranges of concentrations in oyster tissues measured during this study overlap those recalculated from Butler's data, the average concentrations are 2 to 10 times lower. The decline in the concentrations after the restriction of the use of D D T in early 1970s may be due to dilution of these compounds by mixing into pristine areas and/or degradation by biological and environmental processes. Nevertheless, DDT and its metabolities have remained as widespread pollutants in the marine environment.

NOAA's Status and Trends Mussel Watch Program

193

Geographical distribution and temporal variability The geographical distributions of chlorinated hydrocarbon concentrations in sediments or oyster samples were, in general, very similar during both sampling periods. The highest concentrations in sediments samples were mainly encountered in sites located to the east of the Mississippi River, particularly along the coast of Florida, i.e. Choctawhatchee, St Andrew, and Tampa Bays; although some high concentrations were also measured in samples from Galveston and Matagorda Bays. The highest chlorinated hydrocarbon concentrations in oyster tissues were detected in a wider region, to the east of the Mississippi River, than the more localized area found for sediments; particularly for D D T and its metabolites. In Texas, oyster samples from Yacht Club, in Galveston Bay, had comparable concentrations to those encountered in samples from Choctawhatchee or St Andrew Bays. One way to visualize and compare the overall geographic distributions of chlorinated hydrocarbons in sediment and oyster samples from the northern Gulf of Mexico is to rank the sites according to their average total (nonDDT) pesticide, DDT and PCB concentrations and divide them in quartiles. Figure 12 shows the occurrence of each site in the upper and/or lower quartile, i.e. highest and lowest concentration ranges, for sediment and oyster samples. Thus, sediments from the USA-Mexico border to southernmost Florida can be divided in two well differentiated zones. The first, along the Texas coast, had a high predominance of sites with low chlorinated hydrocarbon concentrations. The second, which extends from the TexasLouisiana border to south Florida, shows a predominance of sites with high concentrations, particularly along the Florida shoreline. In the case of oyster samples, sites with highest chlorinated hydrocarbon concentrations were less localized throughout the studied area. In contrast, the lowest concentrations were mainly limited to three areas, i.e. southern Texas, near the Mississippi River Mouth, and southern-most Florida. Although the general distribution of sites with low and high concentrations were, in general, similar for sediments or oysters during 1986 and 1987, there were sites that had significant changes in their average chlorinated hydrocarbon concentrations. Graphic presentations of the data from all 51 sites measured in 1986 and 1987 for the total (non-DDT) pesticides, DDT and its metabolites, and total PCBs in sediments and oysters are presented in Fig. 13 (A through F). Since the x and y scales on these graphs are identical, sites with the same concentrations during both sampling years will fall on the center lines of the graphs (intercept = 0; slope --- 1). Sites that plot above or below these lines show an increase or a decrease in concentrations, respectively, between 1986 and 1987. Sites

194

Jos~ L. Sericano et al.

7

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._~._~

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.

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Fig. 12. Frequency of occurrence of sampling sites in the lowest and highest quartiles for (a) concentrations of sediment contaminants (see Figs 3-5) or (b) concentrations of oyster contaminants (see Figs 6--8). Maximum frequency is 6. The totals of three categories of contaminants (PCBs, DDTs and pesticides) over 2 years (1986, 1987) are given.

NOAA's Status and Trends Mussel Watch Program 10o . .(Non-OoT) .............. ,..,,.~de.

;,

40 10'

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Fig. 13. Sediment and oyster total (non-DDT) pesticide, DDT and PCB concentrations in 1986 versus 1987. Closed circles indicate the sites with statistically significant changes in

concentrations between both sampling years.

showing statistically significant increases or decreases, at the ~ = 0.05 level, were represented by closed circles. In general, sediments showed a larger scatter in concentrations between sites and, consequently, more significant changes than oysters. More than 50% of all the measured chlorinated hydrocarbon concentrations in sediment samples fell beyond the factor-oftwo lines (represented by dotted lines in the graphs). Comparatively, only about 20% of the total oyster data were plotted outside those limits. In 1987, over 20% of all the measurements in sediment samples yielded average

196

Josh L. Sericano et al.

chlorinated hycrocarbon concentrations that differed significantly from the levels encountered during the previous year; the shift in concentrations being mainly to higher values. Oysters had slightly less variable average chlorinated hydrocarbon concentrations with time. Approximately 15% of the total oyster data had significantly different concentrations in 1987 as compared to 1986. Most of the changes resulted in lower concentrations for the second sampling year, particularly for total PCBs where a general decrease in concentrations during 1987 is apparent. In general, most of the significant increases observed in sediment and oyster samples were detected in sites located to the east of the Mississippi River, particularly from Breton Sound to Tampa Bay (Sites No. 30 to No. 47). Almost 90% of all significant changes observed in sediments and oysters corresponded to sites that presented a factor of change equal or greater than two between 1986 and 1987. In contrast, there were several other sites with factor of changes greater than two for which it was not possible to conclude that those changes were statistically significant. This is, in part, due to the large variability encountered among the stations at each of those sites, particularly with sediment samples. The normalization of the sedimentary and tissue chlorinated hydrocarbon data to several ancillary parameters, i.e. grain size, organic matter or lipid percentages, recorded during this study, did not help to explain the large natural variability encountered at some sites. As an example, 'raw' and 'normalized' total DDT concentrations to lipid contents in oysters, measured during 1986, are shown in Fig. 14. The normalization of the data not only did not improve the variability but, in some cases, made it worse. This is mainly because of the much larger variability observed in chlorinated hydrocarbon concentrations than in any of the ancillary parameters mentioned. In the case of lipids, the average 1986 percentages in the northern Gulf of Mexico were 8.08 ___1.68%. No significant Spearman's rank correlation was found when total contaminant loads, i.e. sum of chlorinated pesticides plus PCBs, in all the oyster samples were compared to their lipid percentages. This lack of correlation between chlorinated hydrocarbon concentrations and lipid contents in oysters was also reported for samples collected in Galveston Bay during 1986 (Fox, 1988). The particularly large differences in average chlorinated hydrocarbon concentrations in sediments between both sampling years observed at some sites, e.g. Mississippi Sound-Biloxi Bay (Site No. 34), Choctawhatchee Bay-Shirk Point (Site No. 39), Saint Andrew Bay-Watson Bayou (Site No. 40), and Tampa Bay-Papys Bayou (Site No. 44), appear to reflect different grain size compositions and/or organic contents of the samples. At these sites during the first year an organic-poor, high sand sediment was collected and analyzed. During the second year, samples collected were organic-rich, fine-grained sediments. For example, the percentages of organic carbon in

197

NOAA's Status and Trends Mussel Watch Program

1 2 3 4 5 6 7 8 9 1 0 11 12 13 1 4 1 5 1 6 17 18 1 9 2 0 2 1 22 23 2 4 25 26 2 7 2 8 29 30 31 32 33 34 35 36 37 38 39 4 0 41 42 43 44 45 46 47 48 49 50 51

Lower Lsguna Msdro corpus Christi Corpus Christi Arsnses Bey C o p s n o Bay M e s q u i t e Bay San A n t o n i o Bay San A n t o n i o Bay Esplritu Santo Esplrltu Santo M e t e g o r d a Bay Matagorda Bay Metegorda Bay Mstegorda Bay Galveston Bey Galveston Bay Galveston Bay G a l v e s t o n Bay Sabine Lake C e l c a s l e u Lake Joseph Harbor Bayou Vermillion Bay East Cote Blanche Atchafalaya Bay C s l l l o u Lake Terrebonne Bay Terrebonne Bay Bersterla Bay Beratarle Bay Breton Sound Breton Sound Lake Borgne Mississippi Sound Mississippi Sound Mlssl.'~sippl S o u n d M o b i l e Bay P e n s a c o l a Bay Choctewhetchee Bay Choctawhatchee Bay St. A n d r e w Bay Apalachicola Bay Apalachicola Bay C e d a r Key T a m p a Bay T a m p a Bay T a m p a Bay T a m p a Bay Charlotte Harbor N a p l e s Bay R o o k e r y Bay Everglades

•

A

•

14N •

R

•

•

• m4

m • •

m • m4 • •

•

~ • =

~m • : ; ~.

;

P-a-I

=

~

: :

m

=

:

m

• • i

• i n ~

m : = • •

•

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-

:

~ m •

• • :

=

:

:

-

•I =

:

=

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---

:

=

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=

=

:

• FIB

•

• •

• I4H ~

: = ; = : IIN

~ m • •

100 Total

n 200

u 300

D D E + D D D ÷ D D T in O y s t e r s (ng/g d r y w e i g h t )

00

1000

i 2000

•

Total DDE+DDD+DDT (ng/g L i p i d e , d r y

u 3000

4000

in O y s t e r s weight)

Fig. 14. Comparison of Gulf of Mexico variability in oyster'raw' data (A) and 'normalized data to lipid content (B).

sediments from the stations at Site No. 39, sampled during 1986, ranged from 0.2 to 3.7% whereas samples collected during year II contained 15 to 23% organic carbon. Similarly, the sediments collected at Site No. 44 increased from 0.3 to 1.0% organic carbon and decreased from 90 to 47% sand in 1987 compared to 1986. These variations in sediment composition were accompanied by large differences in pollutant load. Choi & Chen (1976)

198

Josh L. Sericano et al.

have demonstrated that a linear relationship exists between concentrations of chlorinated hydrocarbons and particle sizes within a range of up to 8/~m. Besides the very fine silt and clay fractions, the a m o u n t of sedimentary organic substances is an important factor in controlling the absorption capacity of chlorinated hydrocarbons in marine sediments (Chiou et al., 1983). In this study, total contaminant load in sediments was significantly correlated to total organic carbon content (P < 0.01); approximately 34% of the variability in sediment total concentrations can be explained by this parameter. However, it is important to note that having a significant correlation with the Spearman's rank correlation test does not necessarily mean that such correlation is linear. For this reason, a simple normalization of the raw data may not correct the encountered variability. No significant correlation was detected when total contaminant loads were compared to silt + clay contents in sediments. Hazard levels The US Department of Health and H u m a n Services (1980) have published maximum limits of toxic substances recommended for protection of aquatic biota. The recommended action levels for chlorinated hydrocarbon residues in marine shellfish are as follows: aldrin, dieldrin, heptachlor, and heptachlor epoxide, 0-3 pg g - 1 wet weight, and PCBs 5.0 #g g- a wet weight. Limits for other pesticides in marine shellfish have not been established. Approximately 15 g of wet tissue were used for the analysis of chlorinated hydrocarbons in oysters, yielding about 2"0 g of dry weight material. Using this information, the above recommended limits can be re-expressed, on a dry weight basis, as 37.5 #g g - 1 for PCBs and 2-25 pg g - 1 for individual nonD D T pesticides. All the average concentrations in oyster samples, corresponding to these chlorinated hydrocarbons, as well as all the individual values were below those limits during both sampling years (Tables 3 and 4).

SUMMARY AND CONCLUSIONS Despite the fact that this study was designed to avoid known point-sources of contaminant inputs, the measured concentrations were, in general, within the ranges of concentrations previously reported for coastal areas of the Gulf of Mexico. Chlorinated hydrocarbons are ubiquitous low level contaminants of oysters and sediments from the studied area. The most abundant chlorinated hydrocarbons in oysters and sediments were D D T s and PCBs. In both oyster and sediment samples, total DDTs were

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dominated by D D D isomers, while D D E was significantly higher in oysters than in sediments. Average D D T concentrations, on a dry weight basis, were five times higher in oysters than in sediments. Some differences were observed in the oyster and sediment average PCB compositions. PCB composition in oysters was largely dominated by pentachlorobiphenyls while sediments had a wider distribution of PCBs where hexa-, penta-, tetraand heptachlorobiphenyls were the dominant homologs. Alpha-chlordane, trans-nonachlor and dieldrin were the most abundant (non-DDT) pesticides measured in oysters and sediments. In general, 'hot' spots for chlorinated pesticides and PCBs in oysters and sediments were mainly encountered in Galveston Bay (TX), Tampa Bay (FL) and in a wider area located to the east of the Mississippi River, particularly from Site No. 30 (Breton Sound) to site 40 (St Andrew Bay). After the first two years of study, the objectives of this program for the Gulf of Mexico are partially accomplished. Although distributions of chlorinated hydrocarbons in oysters and sediments from the north coast of the Gulf of Mexico are well identified, with some sites appearing as potential problem areas (e.g. Galveston, Choctawhatchee, St Andrew and Tampa Bays), it is not possible to determine the significance of the observed temporal changes at some sites with only two years of data. Every effort was made to sample the same locations within each site during both sampling periods; however, pollutant load may have variations on a relatively small spatial scale. Continued sampling will allow the identification of long-term trends in the concentrations of chlorinated hydrocarbons for the Gulf of Mexico. A C K N O W L E D G E M ENTS We gratefully acknowledge the efforts of the following: Dr R. R. Fay, who supervised the Status and Trends sampling teams during years I and II as well as the individuals that collected the samples; R. G. Fox, B. GarciaRomero and M. P. Wood, for helping in the process of sample analyses and D. A. DeFreitas and T. J. White, for doing the computational work. This research was supported by the National Oceanic and Atmospheric Administration, contract No. 50-DGNC-5-00262, through the Texas A & M Research Foundation, Texas A & M University,

REFERENCES Addison, R. F. (1976). Effects of Pollutants on Aquatic Organisms, ed. A. P. H. Lockwood., University Press, Cambridge.

200

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Baird, R. G., Thompson, N. P., Hopkins, T. L. & Weiss, W. R. (1975). Chlorinated hydrocarbons in mesopelagic fishes of the eastern Gulf of Mexico. Bull. Mar. Sci., 24, 473-81. Ballschmiter, K. & Zell, M. (1980). Analysis of polychlorinated biphenyls (PCB) by glass capillary gas chromatography. Composition of technical Aroclor and Clophen-PCB mixtures. Z. Analyt. Chem., 302, 20-31. Boon, J. P., Van Zantvoort, M. B., Govaert, M. J. M. A. & Duinker, J. C. (1985). Organochiorines in benthic polychaetes (Nephtys spp.) and sediments from the southern North Sea. Identification of individual PCB components. Neth. J. Sea Res., 19, 93-109. Butler, P. A. (1973). Residue in fish, wildlife and estuaries. Organochlorine residues in estuarine mollusks, 1965-72. National Pesticide Monitoring Program. Pest. Monit. J., 6, 238-46. Butler, P. A. & Schutzmann, R. L. (1978). Residues of pesticides and PCBs in estuarine fish, 1972-1976. National Pesticide Monitoring Program. Pest. Monit. J., 12, 51-59. Chiou, C. T., Porter, P. E. & Schmedding, D. W. (1983). Partition equilibria of nonionic organic compounds between soil organic matter and water. Environ. Sci. Technol., 17, 227-31. Choi, W. W. & Chen, K. Y. (1976). Association of chlorinated hydrocarbons with fine particles and humic substances in nearshore surficial sediments. Environ. Sci. Tech., 10, 782-6. Crosby, D. G. (1969). The nonmetabolic decomposition of pesticides. In Biological Effects of Pesticides in Mammalian Systems, ed. H. F. Kraybill, Ann. N Y Acad. Sci., 160, 82-96. De la Cruz, A. A. & Lue, K. Y. (1978). Mirex incorporation in estuarine animals, sediments and water, Mississippi Gulf coast, 1972-1974. Pest. Monit. J., 12, 40-2. Duinker, J. C., Hillebrand, M. T. J. & Boon, J. P. (1983). Organochlorines in benthic invertebrates and sediments from the Dutch Wadden Sea; Identification of individual PCB components. Neth. J. Sea Res., 17, 19-38. Duke, T. W., Lowe, J. I. & Wilson, A. J. (1970). A polychlorinated biphenyl (Aroclor 1254) in the water, sediment and biota of Escambia Bay, Florida. Bull. Environ. Contam. Toxicol., 5, 171-80. Elder, J. F. & Mattraw Jr, H. C. (1984). Accumulation of trace elements, pesticides and polychlorinated biphenyls in sediments and the clam Corbicula manilensis of the Apalachicola River, Florida. Arch. Environ. Contam. Toxicol., 13, 453-69. Farrington, J. W., Albaiges, J., Burns, K. A., Dunn, B. P., Eaton, P., Laseter, J. L., Parker, P. L. & Wise, S. (1980). Fossil Fuels. In The International Mussel Watch: Report of a Workshop sponsored by the Environmental Studies Board Commission on Natural Resources. National Research Council, pp. 7-77. Farrington, J. W., Risebrough, R. W., Parker, P. L., Davis, A. C., DeLappe, B. W., Winters, J.K., Boatwright, D. & Freq, N. M. (1982). Hydrocarbons, Polychlorinated Biphenyls and DDE in Mussels and Oysters from the US Coast, 1976-1978. Tech. Report, WHOI-82-42. Woods Hole Oceanogr. Inst., MA, 106 pp. Farrington, J. W., Goldberg, E. D., Risebrough, R. W., Martin, J. H. & Bowen, V. T. (1983). US 'Mussel Watch' 1976-1978: An overview of the trace metal, DDE,

NOAA's Status and Trends Mussel Watch Program

201

PCB, hydrocarbon and artificial radionuclide data. Environ. Sci. Technol., 17, 490-6. Fay, R. R. & Newland, L. W. (1972). Organochlorine insecticide residue in Aransas Bay, Texas. Pest. Monit. J., 6, 97. Fox, R. G. (1988). Spatial and Temporal Variation of Polynuclear Aromatic Hydrocarbons, Pesticides and Polychlorinated Biphenyls in Crassostrea virginica and Sediments from Galveston Bay, Texas. MS thesis, Department of Oceanography, Texas A & M University, College Station, Texas, 92 pp. Folk, R. L. (1974). Petrology of Sedimentary Rocks. Hemphill, Austin, Texas. 160 pp. Fries, G. F. (1972). Degradation of chlorinated hydrocarbons under anaerobic conditions. In Fate of Organic Pesticides in the Aquatic Environment. Advances in Chemistry, Series III, ed. R. F. Gould. American Chemical Society, Washington, DC. pp. 256-70. Gerlach, S. A. (1981). Marine Pollution: Diagenesis and Therapy. Springer-Verlag, New York, 218 pp. Giam, C. S., & Chan, H. S. (1978a). Heavy molecular weight hydrocarbons in macroepifauna and macronekton samples, 5-1 to 5-23. In Environmental Studies, South Texas Outer Continental Shelf, Biology and Chemistry. A final report prepared by the University of Texas for the Bureau of Land Management, Contract AA550-CT7-11. Giam, C. S. & Chan, H. S. (1978b). High molecular weight hydrocarbons in macronekton and Spondylus samples. In South Texas Topographic Features Study. A final report prepared by Texas A & M Research Foundation and the Texas A & M Dept of Oceanography for the Bureau of Land Management, Contract AA550-CT6-18. Giam, C. S., Hanks, A. R., Richardson, R. L., Sackett, W. M. & Wong, M. K. (1972). DDT, DDE and polychlorinated biphenyls in biota from the Gulf of Mexico and Caribbean Sea--1971. Pest. Monit. J., 6, 139-42. Giam, C. S., Richardson, R. L., Wong, M. K., Hanks, A. R. & Sackett, W. M. (1973). Chlorinated hydrocarbons in plankton from the Gulf of Mexico and Northern Caribbean. Bull. Environ. Contam. Toxicol., 9, 376-82. Giam, C. S., Richardson, R. L., Taylor, D. & Wong, M. K. (1974). DDT, DDE and PCBs in tissues of reef dwelling groupers (Serranidea) in the Gulf of Mexico and the Grand Bahamas. Bull. Environ. Contam. Toxicol., 12, 189-92. Jan, J. & Josipovic, D. (1978). Polychlorinated terphenyls in hens--The behaviour of ortho, meta and para isomers. Chemosphere, 11, 863-6. Karickhoff, S. W. (1981). Semi-empirical estimation of sorption of hydrophobic pollutants on natural sediments and soils. Chemosphere, 10, 833-46. Livingston, R. J., Thompson, N. P. & Meeter, D. A. (1978). Long-term variation of organochlorine residues and assemblages of epibenthic organisms in a shallow north Florida (USA) estuary. Mar. Biol., 46, 355-72. MacLeod, W. D., Brown, D. W., Friedman, A. J., Burrows, D. G., Maynes, O., Pearce, R. W., Wigren, C. A. & Bogar, R. G. (1985). Standard Analytical Procedures of the NOAA National Analytical Facility, 1985-1986. Extractable Toxic Organic Compounds. (2nd edn), US Department of Commerce, NOOAA/q~MFS. NOAA Tech. Memo. NMFS F/NWC-92. M atsuo, M. (1980). A thermodynamic interpretation of bioaccumulation of Aroclor 1254 (PCB) in fish. Chemosphere, 9, 671-5.

202

Josk L. Sericano et al.

Melnikov, N. M. (1971). Chemistry of Pesticides. Springer-Verlag, New York, 479 pp. National Oceanic and Atmospheric Administration (1987). National Status and Trends Program--A Preliminary Assessment of Findings of the Benthic Survillance Project--1984. NOAA Office of Oceanography and Marine Assessment, Rockviile, MD, 81 pp. Niimi, A. J. & Oliver, B. G. (1989). Distribution of polychlorinated biphenyl congeners and other halocarbons in whole fish and muscle among Lake Ontario saimonids. Environ. Sci. Technol., 23, 83-88. Ott, L. (1984). An Introduction to Statistical Methods and Data Analysis. (2nd edn), Duxbury Press, Boston, 775 pp. Patil, J. C., Matsumura, F. & Boush, G. M. (1972). Metabolic transformation of DDT, dieldrin, aldrin and endrin by marine microorganisms. Environ. Sci. Technol., 6, 629-32. Petrocelli, S. R., Anderson, J. W. & Hanks, A. R. (1974). DDT and dieldrin residues in selected biota from San Antonio Bay, Texas, 1972. Pest. Monit. J., 8, 167-72. Pruell, R. J. & Quinn, J. G. (1985). Geochemistry of organic contaminants in Narragansett Bay sediments. Estuar. Coast. Shelf. Sci., 21, 295-312. Ramos, L. & Prohaska, P. G. (1981). Sephadex LH-20 chromatography of extracts of marine sediment and biological samples for the isolation of polynuclear aromatic hydrocarbons. J. Chromatogr., 211,284-9. Risebrough, R. W., DeLappe, B. W., Walker II, W., Simoneit, B. T., Grimalt, J., Albaiges, J. & Regueiro, J. A. G. (1983). Application of the Mussel Watch concept in studies of the distribution of hydrocarbons in the coastal zone of the Ebro Delta. Mar. Pollut. BulL, 14, 181-7. Rosales, M. T. L., Botello, A. V., Bravo, H. & Mandelli, E. F. (1979). PCBs and organochlorine insecticides in oysters from coastal lagoons of the Gulf of Mexico, Mexico. Bull. Environ. Contam. ToxicoL, 21, 652-6. Samuelian, J. & O'Connor, J. M. (1985). Structure-activity relationships and accumulation of PCB congeners in estuarine fishes: A field study (Abstract only). Estuaries, 8, 83A. Shaw, G. R. & Connell, D. W. (1980). Relationships between steric factors and bioaccumulation of polychlorinated biphenyls (PCBs) by the sea mullet (Mugil cephalus Linnaeus). Chemosphere, 9, 731-43. Shaw, G. R. & Connell, D. W. (1982). Factors influencing concentrations of polychlorinated biphenyls in organisms from an estuarine ecosystem. Aust. J. Mar. Freshwater Res., 33, 1057-70. Shaw, G. R. & Connell, D. W. (1984). Physicochemical properties controlling polychlorinated biphenyl (PCB) concentrations in aquatic organisms. Environ. Sci. Technol., 8, 18-23. Shaw, D. G., Hogan, T. E. & McIntosh, D. J. (1985). Hydrocarbons in the sediments of Port Valdez, Alaska: Consequences of five years' permitted discharge. Estuar. Coast. Shelf Sci., 21, 131-44. Snedecor, G. W. & Cochran, W. G. (1980). Statistical Methods. (7th edn), Iowa State University Press, Ames, 507 pp. Tulp, M. Th. M. & Hutzinger, O. (1978). Some thoughts on aqueous solubilities and partition coefficients of PCB, and the mathematical correlation between bioaccumulation and physico-chemical properties. Chemosphere, 10, 849-60. US Department of Health and Human Services (1980). Action Levels for Poisonous

NOAA's Status and Trends Mussel Watch Program

203

or Deleterious Substances in Human Food and Animal Food. US Department of

Health and Human Services, Public Health Service, Food Drug Administration. Walker, C. H. (1975). Variations in the intake and elimination of pollutants. In Organochlorine Insecticides: Persistent Organic Pollutants, ed. F. Moriarty. Academic Press, New York, pp. 73-130. Wolfe, N. L., Zepp, R. G., Paris, D. F., Boughman, G. L. & Hallis, R. C. (1977). Methoxychlor and DDT degradation in waters: Rates and products. Environ. Sci. & Technol., 11, 1077-81. Woodwell, G. M., Craig, P. P. & Horton, A. J. (1971). DDT in the biosphere: Where does it go? Science, 174, 1101-7.