Georges bank monitoring program: hydrocarbons in bottom sediments and hydrocarbons and trace metals in tissues

Marine Environmental Research 22 (1987) 33-74

Georges Bank Monitoring Program: Hydrocarbons in Bottom Sediments and Hydrocarbons and Trace Metals in Tissues Charles R. Phillips, James R. Payne, James L. Lambach*, Garry H. Farmer & Robert R. Sims, Jr Science Applications International Corporation, Applied Environmental Sciences, 476 Prospect Street. La Jolla. CA 92037, USA (Received 15 April 1985: revised version received 29 September 1986: accepted 1 November 1986)

ABSTRACT Hydrocarbons in sediments and hydrocarbons attd trace metals in tissues froth Georges Bank were analyzed to evaluate potential changes to the benthic environment resulting.from explorato O, drilling operations. Sediment hydrocarbon concentrations varied with grain size: concentrations up to 2 5 Itg/g dry weight total aromatic equivalents occurred in the fine-grained sediments of Lydonia Canyon and the "Mud Patch' area south of Martha's Vineyard, whereas concentrations were less than I #g/g dry weight in sediments from the shallow areas of Georges Bank, at a regional control site, and at the site of drilling operations. Increases in total aromatic equivalentsJFom approximately O"1 l~g/g dry weight to 0.4 #gig dr)' weight were measured in sedhnents /?ore a site 0.25kin from the drill rig concurrent with drilling operations. Petrogenic hydrocarbons were detected in both drilling fluid extracts attd in sediments collected during drilling operations, suggesting short-term deposition of drilling discharges in near-rig sediments. Drilling discharge residues were not observed in the near-rig sediments one month after drilling operations were terminated. Furthermore, hydrocarbon residues from drilling discharges were not observed in sediments from stations located at distances greater than 6 kin from the drill site either during or subsequent to the drilling operations. * Present address: Department of Polymer Engineering. University of Tennessee, Knoxville, Tennessee, USA. 33

Marine Environ. Res. 0141-1136/87 $0350 ~8~ Elsevier Applied Science Publishers Ltd, England, 1987. Printed in Great Britain

34

Charles R. Philhps et al. L'ptake or accumulation o f drilling fluid components', including, trace metals and petroleurn hydrocarbons, was no~ detected in tissues o f Arctica i s l a n d i c a . Hydrocarbons and trace metals" in tissues were similar to predrilling concentrations.

INTRODUCTION The Georges Bank Monitoring Program was initiated in t981 by the US Department of the Interior. Minerals Management Service, to determine the fate of discharges from exploratory oil and gas operations and potential impacts of drilling operations on the benthic environment of Georges Bank. Benthic environments are potential sinks for discharged drilling muds and cuttings, and benthic organisms exposed to these materials may be subject to acute or sublethal toxicity (National Research Council, 1983). The Georges Bank Monitoring Program included studies to evaluate the chemical and biological effects associated with exploratory drilling operations. This paper describes the results of the analyses of hydrocarbons in bottom sediments and hydrocarbons and trace metals in tissues of benthic organisms. The specific objectives of this study were to: (1)

(2)

(3)

Determine if there is evidence of" petroleum hydrocarbon contamination in bottom sediments and I'auna at selected sites in the area (Fig. 1) and, if so, whether the exploratory drilling operations are the source of contamination. Determine if there is evidence ot" trace metal contamination of benthic fauna and whether exploratory drilling operations are the source of the contamination. Determine if changes in metal and'or hydrocarbon concentrations in fauna and sediments persist after drilling is completed.

This study comprised three consecutive one-year programs. Detailed resuits from the three programs are presented in Payne et al. (1982, 1983, 1985a, respectively). Results from separate studies of trace metals in bottom sediments and benthic infaunal monitoring are presented elsewhere (Bothner et al., 1982, 1984, 1985; Maciolek-Blake et al., 1984). Pre-drilling concentrations of trace metals and hydrocarbons in sediments and faunal tissues from Georges Bank were measured during the New England OCS Environmental Benchmark Program (Alpert, 1978). Concentrations and chemical characterizations of hydrocarbons in bottom sediments are discussed by Boehm et al. (1979), Boehm (1984) and Boehm & Farrington (1984). Pre-drilling concentrations o£ total hydrocarbons (saturated (FL) plus aromatic (F 2) fractions from gas chromatographic

Georges Bank monitoring pr,)~ram

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analyses1 in surface sediments of Georges Bank and adjacent areas (e.g. lower Gulf of Maine) ranged from 0"2 to 20 # g g dry weight (Boehm et al., 1979). Observed levels were consistent with values for sediment hydrocarbons from other locations within the general region (Farrington & Tripp, 1977: Boehm & Quinn. 1978: Laflamme & Hites. 1978). Relatively higher hydrocarbon concentrations occurred in the fine-grained, organicrich sediments of depositional environments, whereas lower concentrations occurred in the coarse-grained sands from the shallower areas of the Bank, especially along the eastern edge and in the central region of the Bank where sediments contained less than 1% silt and clay-sized materials (Boehm, 1984: Boehm & Farrington, 1984). A large seasonal variability in sediment hydrocarbons was noted and believed to reflect active resuspension and erosion of surface sediments in shallow regions and seasonal contributions of biogenic hydrocarbons, particularly to depositional environments (Boehm, 1984). Contributions of terrestrial hydrocarbons were suggested by relatively constant levels of C, o n-alkane (nonacosane), while marine biogenic sources included seasonally-varying levels of pristane. The Gulf of Maine appeared to be a primary source for sediment hydrocarbons, although sporadic inputs of pelagic tar specks may have provided localized and episodic contributions of petrogenic hydrocarbons (Boehm et al., 1979: Hoffman & Quinn, 1979). Results from these studies suggested that the Georges Bank region received inputs of hydrocarbon and trace metal contaminants from several sources prior to oil and gas exploration and development operations. Possible sources include: petroleum residues from tanker ballast cleaning (Boehm e t a / . , 1979) and oil spills (e.g. Argo Merchant) (Hoffman et al., 1979); aeolian transport of pyrolytic polycyclic aromatic hydrocarbons (Hauser & Pattison, 1972; Boehm & Farrington, 1984) and alkanescycloalkanes (Farrington et al., 1977): riverine transport of sewage effluent (Van Fleet & Quinn, 1977); ocean dumping operations (Farrington & Tripp, 1977); and particulate coal residues (Tripp et al., 1981). Exploratory drilling operations in Block 312 on Georges Bank were initiated in December, 1981 and continued until June, 1982. During the seven months of drilling an estimated 750 tons of drilling fluids and 1200 metric tons of cuttings were discharged to the marine environment. The bulk drilling fluid discharge contained an estimated 500 tons of barite (barium sult'ate) and an estimated 525 liters of diesel fuel (Payne et al., 1982; Maciolek-Blake et al., 1984). Bulk discharges of spent drilling¢fluids occurred periodically during the drilling operations, whereas smaller volumes of muds adhering to cuttings were discharged continuously (Payne et al., 1982). A summary of drilling activities and associated discharges in Block 312 is presented in Table 1. Exploratory drilling operations also were

Georges Bank monitoring program

39

conducted in Block 410, approximately 50 km east-southeast of Block 312 (Bothner et al., 1984), An estimated 600 metric tons of drilling fluids were discharged at this site between July, 1981 and March, 1982 (MaciolekBlake et al., 1984). The Georges Bank Monitoring Program was initiated in July, 1981. Two sampling cruises, completed prior to initial drilling operations on Block 312, were intended to provide sufficient information when combined with the results from previous studies to characterize pre-drilling conditions. Additionally during the first year of the study, representative samples of the spent drilling muds were analyzed for hydrocarbons to provide a "fingerprint' for evaluating sites and quantities of discharged material accumulation on Georges Bank. Results from those analyses are discussed briefly in this paper: further details are presented elsewhere (Payne et a/., 1982,

1985h).

METHODS A N D MATERIALS Sample collection Samples were collected quarterly from July. 1981 to June, 1984 (Table 2). Sample cruises M-I and M-2 were conducted prior to drilling; cruises M-3 TABLE 2 Georges Bank Monitoring Program Cruise Dates Cruise No.

Dates

lessel

Pre-drilling M-I M-2

July 6 throu,,h July 23, 1981 November 9 through November 21, 1981

RV Eastw~trd RV Oceanus

February 10 through February 21, 1982: February 27. 1982 (Station 15 only) May I0 through May 18, 1982

RV Endeavor R V .4steri~s RV Cape Henlopen

July 21 through July 28, 1982 November 19 through November 28, 1982 February 5 through February I 1. 1983 May 13 through May 21. 1983 July [3 through July 20, 1983 November 13 through November 19, 1983 February 1 through February 7. 1983 June 2 through June 9, 1984

RV RV RV RV RV RV RV RV

During drilling M--3 M--4

After drilling M-5 M-6 M-7 M-8 M-9 M-10 M-II M-12

Oceanus Oc eam~s Endeavor Gvre Gyre Oceanus Oceanus Gyre

Charles R. Phillips et al.

40

and M-4 occurred during drilling, and cruises M-5 to M-12 were from approximately one month to two years after drilling was terminated. Samples of bottom sediments and benthic fauna were collected for hydrocarbon and trace metal analyses from both a near-rig array of stations, from 0-25 to 6-0 km from the drill rig (Rowan-Midland),and from regional stations located throughout the Lease Sale 42 area. Regional stations (Fig. 1) were intended to assess broad-scale perturbation of the benthic environment from drilling activities within the area. Near-rig stations (Fig. 2) were selected to monitor changes around an active drill rig. Sediment samples from hydrocarbon analyses were collected at each of three regional stations (2-R, 7-R/7a-R and 13-R) and three near-rig stations (5-1, 5-18 and 5-28). Tissue samples for hydrocarbon and trace metal analyses were collected at CROSS-SHELF ,il

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Georges Bank monitoring program

41

one regional station (Station I-R) and from the near-rig stations (Station 5). These stations were sampled throughout the study, except that after the first year Station 7-R was relocated (and designated Station 7a-R) at a site of greater sediment deposition (head of Lydonia Canyon) that was more appropriate than Station 7-R for monitoring accumulation of drillingrelated discharges. Triplicate sediment samples were collected with a 0-1 m-', Teflon-coated, modified, Van Veen grab. The upper 2 cm of sediments (500 to 800 g) were removed from the middle portion of the sampler (to avoid contamination) using a solvent-cleaned, Teflon-coated scoop. The sides of the scoop are 2 cm in height, providing a guide for consistent sampling depths. Samples were transferred to solvent-cleaned Teflon jars and frozen. Benthic fauna (Arctica islandica) were collected with a modified rocking chair dredge and,/ or a 10-m otter trawl. Organisms collected for hydrocarbon analyses were rinsed with filtered seawater, wrapped in solvent-rinsed aluminium foil and frozen. Organisms for trace metal analyses were rinsed with filtered seawater, placed in plastic bags and frozen. Samples of spent drilling fluids for chemical characterization were obtained from pesonnel on-board the R o w a n - M i d l a n d during various phases of the drilling operations. Unfortunately, samples of drill cuttings could not be obtained for analyses.

Sample preparation Sediment and drilling fluid samples for hydrocarbon analyses were extracted using a modified shaker-table procedure with a 65:35 v;v mixture of methylene chloride and methanol (Payne et al., 1980; Brown et al,, 1980). Sample extracts were concentrated using a Kuderna-Danish (K-D) apparatus, and saponified with a IN KOH reflux according to the procedure of Wakeham (1977). The extracts subsequently were dried with Na2SO ~, concentrated to a volume of 10ml, and solvent exchanged in spectrograde cyclohexane (BP:80 to 81~C). Tissues for hydrocarbon analyses were homogenized with an ultrasonic/mechanical tissue homogenizer, and extracted in methylene chloride, with anhydrous sodium sulfate, in the homogenizer. Extracts were then filtered through sodium sulfate, reduced with a K-D apparatus, saponified, dried and solvent exchanged into cyclohexane as described above. Separate aliquots of the homogenized tissue were removed and dried for three to five days to a constant weight in a 95:C convection oven to determine per cent moisture. Tissue samples were prepared for trace metal analyses (except Hg, V, and Ba) using a method modified from Abercrombie et al. (1979). Tissues were freeze-dried, homogenized and then ashed overnight in a low temperature asher. The ashed tissue material was digested in redistilled HNO 3, heated

42

Charles R. Phillips et al.

on a hot plate, evaporated to near dryness, and brought to volume with deionized filtered water. Homogenized wet tissue samples for Hg analyses were added to borosilicate bottles, with polypropylene screw caps, containing 5 ml of redistilled HNO 3. and heated in a 90°C water bath for two hours after adding Hg-free H_,SO~. The samples were cooled, Hg-free K M n O 4 was added, and the samples were then reheated for one hour. National Bureau of Standards (NBS) oyster tissue and bovine liver, and sample blanks, were prepared for each batch of tissue samples in the same manner. Acid-digested tissues for neutron activation analyses of vanadium were added to a column containing hydrated antimony pentoxide, collected in acid-cleaned beakers, and taken to near dryness on a low heat hot plate. Residues were redissolved in repeated 2N HNO 3 rinses which were combined in acid-cleaned polyethylene vials and irradiated in the University of Missouri reactor for 180s with a neutron flux of 25 x 1012 n c m -2 s- t. Aliquots of digested tissue tbr barium analyses were transferred to acidcleaned polyethylene vials, heat sealed and irradiated for five minutes. Following irradiation, samples were transferred to polypropylene beakers containing 100mg each of NaCI and KCI and 20mg of a Ba 2+ carrier in 0-5N HNO3: 2ml of IN HzSO 4 were added to induce precipitation of BaSO~. The solution was then filtered onto a 0.4ttm pore filter which was washed with solutions of NaC1/KCI and IN H2SO 4. Sample analysis Sediment and tissue extracts were screened initially for aromatic hydrocarbons using a synchronous scanning UV/fluorescence technique similar to that of Wakeham (1977). Spectra were obtained with a Perkin-Elmer M PF-44 fluorescence spectrophotometer, in corrected excitation and corrected emission modes, over a range of 230 to 600 nm with a 30 nm offset between excitation and emission wavelengths. Prior to screening samples, tests to determine the optimal response range and linearity of emission peak heights at various concentrations were conducted using standards of individual, as well as mixed one-ring, two-ring and multi-ring, aromatic compounds (Table 3). Emission wavelength ranges of 290-320 nm, 320-365 nm and 365-480 nm for mono-, di-, and polynuclear compounds were selected based on the relative positions of prominent emission peaks. Selected wavelength ranges agreed with previously reported values (Wakeham, 1977), although emission wavelengths for some polynuclear aromatics, such as chrysene and phenanthrene, exhibited considerable overlap with those for two-ring aromatic compounds. Peak areas within each wavelength band were integrated by planimetry.

Georges Bank monitoring program

43

The total concentration of one-ring c o m p o u n d s in the standard was divided by the integrated area (in arbitrary planimeter area units) to yield a response factor (6.5 x 10-'t #g m l - t unit area) for this class o f compounds; corresponding response factors for two-ring (4.9 x 10 -'t/~g ml-~ unit area) and multi-ring (8.2 x 10- 5/ag m l - 1 unit area) c o m p o u n d classes were determined in a similar manner. TABLE 3

Composition of the Mixed Aromatic Standard used for UV/Fluorescence Measurements

1-ring compounds Tuluene Ethylbenzene p-Xylene o-Xylene Cumene n-Propylbenzene Mesitylene p-Cumene n-Butylbenzene n-Hexylbenzene n-Octylbenzene 2-ring compounds Naphthalene l-Methylnaphthalene 2-Methylnaphthalene 2,6-Dimethylnaphthalene 2,3,5-Trimethylnaphthalene Multi-ring compounds Anthracene Phenanthrene l-Methylphenanthrene Chrysene Pyrene Benzo(a)pyrene Benzo(e)pyrene Benzo(b)anthrocene

Responsefactor

6"5 x 10-~ ~gml- t unit area

4-9 x 10-'~gml TM unit area

8.2 x 10- 5og ml - ' unit area

The mixed aromatic standard was scanned at several concentrations under the same operating condition used for analysis of samples, and emission peak heights were plotted against concentrations for each c o m p o u n d class to determine linearity. Detector linearity was observed within a range of 10 to 10,000 n g m l - 1, and a nominal concentration of 1,000 ng ml-1 was used for calculating response factors to ensure linear detector responses for

44

Charles R. Phillips et al.

all aromatic compound classes. Sample extracts were concentrated or diluted to produce fluorescence responses within an order of magnitude of this value. All sediment and tissue samples were screened, and the peak areas within the wavelength bands were measured and compared with emission responses for the mixed aromatic compound standards. Concentrations of the one-ring, two-ring, and multi-ring aromatic compounds are reported as total aromatic equivalents (TAE). Sequential sample dilutions were performed on the highly colored extracts from silty, organic-rich sediments to preclude quenching. Selected sediment, drilling fluid, and tissue extracts containing relatively high levels of di- and tri-cyclic polynuclear aromatic compounds were fractionated using methods described by Payne et al. (1980) and Brown et al. (1980) to remove the non-saponifiable lipids and to separate the saturated, aromatic, and polar fractions, Extract fractions were analyzed using fusedsilica capillary, flame ionization detector-gas chromatography (FID-GC). Methods for quantifying concentrations of individual resolved peaks and unresolved complex mixtures (UCM) are described in Payne et al. (1985b). KOVAT index values (Kovats, 1958) were assigned to all even and odd nalkanes between C s and C~_, according to the corresponding retention times, and to each branched or cyclic compound by linear interpolation of the retention times of adjacent n-alkanes. Index values for resolved peaks in the aromatic fraction were assigned by direct correlation between the individual retention times and those retention times of spiked standards. Selected extracts were also subjected to analyses by capillary gas chromatography:mass spectrometry on a Finnegan 4021 GC/MS with an Incos Data System (DS). All GC. MS data sets were first screened using a selected ion monitoring technique for 42 polynuclear aromatic compounds. Confirmation of compound identities was obtained both by examining spectral matches between the unknown and the spectral library data base and by comparing the compounds" retention time and KOVAT index value with those of aromatic hydrocarbon standards. Generally, only DS spectral matches with a purity greater than 800 were accepted for compound confirmation. Trace metals (AI, Cd, Cr, Cu, Fe, Pb, Ni and Zn) were analyzed by flame and flameless atomic absorption spectrophotometry; Hg was quantified by cold vapor atomic absorption spectrophotometry. Standard additions were performed routinely, and standards and blanks were analyzed in the same manner as the samples. Vanadium was measured by counting 5-'V (at 1434 KeV) for 180 s on a 45 cc Ge(Li) spectrometer: ~39Ba was counted (at 166 KeV) for five minutes using a high resolution Ge(Li) detector with a gamma ray spectrometer.

Geor~es Bank monitorin¢ program

45

RESULTS Hydrocarbons in sediments Aromatic hydrocarbon concentrations, quantified by UV fluorescence, in sediments from the regional and near-rig stations are summarized by cruise in Table 4. Seasonal changes of TAE concentrations in sediments from regional (2-R. 7a-R, and 13-R) and near-rig {5-l, 5-18, and 5-28) stations are shown in Figs 3 and 4, respectively. TABLE 4 Mean Concentrations of Total Aromatic Equivalents in Sediments by UV Fluorescence (Numbers in Parenthesis represent One Standard Deviation for n = 3}

Total aromatic equivalent~ (it,eL -~ dry we~.ht) ,Vear-ri~ stations Regional stations .~-_8 7a-R 13-R 5-18 - "' 2-R 5-1

Cruise Date

Pre-drilling M-I 7'81 M-2

0.091

0.10 (006} 0.019 (0.02)

0.084 (0'05) 0.042 (0-04}

0056 (0.01) 0-047 (0-01)

N A

15

NA

25

0'040 (0'02) 0-060 (0.02}

0'._ ~ (0"31} 0"053 (0.02}

0"029 {0"01) 0"037 (0-01)

N,A

2"0

N A

-~'~ -

0-080 (0.007} 014 (0"10) 0" 1 I

0-051 ({}01) 0.048 (0"02) 0"037

12 (078) 16 (0"21} 1"6

16

032 (0"08} 0"46

0-12 (0-02} (}-16 (0'08} 0' 13

0,97 {0-07) 0"98

{0 15}

(0-02}

(0-10}

(0.(}2)

(0.46}

(0.29)

0-34 {0-09) 0.57 (036) 0.37 (0-t6} 0.37 {0-08) 038 (0-13)

0-12 (004) 0.47 (0.17) 0.18 {0.10) 0-23 {01 I) 0-34 (0.24)

0-05l (0-008} 012 (0-05) 0.017 ({}.008) 0. I0 (002} 0.064

0.040 ({}-02} 0.065 (0.01) 0.055 (0.07} 0-034 (002) 0-070 (005)

12 ({}13) 2.1 (0'13} 22 (0.02) 2-1 (0.06) I-3 {0-11}

1.4 {0.27) 2-0 (0.21) 1.9 (030) 1.7 (0-05) 1.6 {0-58}

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0"43

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0.40

M-6

1182

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283

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5,83

M-9

783

M-10

1183

M-II

284

M-12

684

N A = Not analyzed. Mean values based on a minimum of three replicates, except Station 5-t samples from 7/8 I 7 82 and Station 13- R from 7 8 1 - 5 82 which represent a single analysis of homogenous mixture of three replicate samples. Standard deviations for each mean value are shown in Figs 3 and 4 for regional and near-rig stations, respectively.

Charles R. Phillips et at.

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Higher TAE concentrations occurred in finer grained silts and clays from depositional environments, whereas lower concentrations occurred in the coarser grained sands from shallow areas on the Banks. The grouping of stations according to differing sediment size class and TAE concentrations is illustrated in Fig. 5. Two main groupings, with an intermediate subset, are apparent: samples from the two depositional areas comprise one grouping and samples from station 2-R and from the near-rig stations comprise the second grouping. Sediments from Station 5-1 collected during cruises M-3 through M-12 form the intermediate grouping. These groupings correspond roughly to Boehm's (1984) Group A, B, and C type sediments, respectively. Sediments from Station 2-R and t¥om the near-rig stations have a large mean grain size of I phi and low (less than I%) amounts of silts and clays (Bothner et al., 1985), reflecting the strong tidal and storm-generated bottom currents which resuspend and transport smaller grained sediments across the shelf (Butman & Folger, 1979; Twichell et al., 1981: Butman & Moody, 1983~. In contrast, sediments from the Mud Patch, considered a depositional site for sediments from areas upcurrent of Georges Bank (Bothner et al., 1981), have a mean grain size of 6-3 phi with approximately 95% silts and clay (Bothner et al., 1984). Lydonia Canyon is also considered a site of active sediment deposition, and sediments are characterized by a mean phi of 4.3 with up to 30% silts and clay (Bothner et al., 1985). Mean TAE concentrations in sediments from the control station (2-R) ranged from 0-029 to 0-070/~g/g dry weight during the study. Total hydrocarbon concentrations measured by F I D - G C ranged from 0-015 to 0.23 l~g g-~ dry weight, and generally were lower than values reported by Boehm (1984) for this site. No consistent seasonal patterns or increases in aromatic equivalents during drilling operations were apparent. Results from a one-way ANOVA of log-transformed TAE data indicated no statistically significant differences in concentrations between cruises in the control station. Furthermore, extracts of sediments from Station 2-R analyzed by F I D - G C contained no resolved compounds in the saturated fraction, and only one unidentified sterol in the aromatic fraction. The low concentrations of aromatic hydrocarbons and extremely simple chromatographic profiles reflect the absence of petroleum hydrocarbons (Group B type sediments; Boehm, 1984). Mean TAE concentrations in sediments from 'Mud Patch" (Station 13-R) and Lydonia Canyon (station 7a-R) were similar, ranging from approximately 1.0 to 2'5 ttg/g dry weight, and generally 30 to 40 times higher than corresponding concentrations in sediments from Station 2-R. The highest TAE concentrations measured during this study (2"5ttgg-tdry weight) were from Station 13-R during November, 1981. Total hydrocarbon concentrations ranged from 2-1 to 6"3 g~gg - t and from 0-9 to 15-2 gLgg-1 dry

Georges Bank monitorin~ program

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weight for Station 7a-R and 13-R. respectively. No seasonal trends or changes in sediment TAE concentrations due to drilling activities were apparent at either site, although significant differences (p<0-05) between means for log-transformed TAE concentrations in Station 13-R sediments were detected with a one-way ANOVA: however, no cruise groups could be distinguished based on a Duncan multiple range test. In contrast, means tbr Station 7a-R sediment hydrocarbon levels bet~veen cruises were not significantly different. The F~ (ractions of extracts of sediments from Stations 7a-R and 13-R typically contained a series of resolved n-alkanes in the C23 to C33 range with an odd-carbon predominance and a small UCM centered around C:0. The F 2 tractions contained predominantly biogenic alcohols, aldehydes and sterenes, although several PAHs such as phenanthrene, fluoranthene, chrysene and benzo(b)fluoranthene were also present at concentrations from approximately I to 20 ng g- ~ dry weight. The odd-carbon predominance, small UCM, and contributions by terrestial plant wax hydrocarbons are characteristic of sediments from depositional sites with a small mean grain size and greater than 10% silt and clay content (Group A type sediments: Boehm, 1984). At the near-rig stations (5-1, 5-18, and 5-28), mean TAE concentrations were similar to, or slightly higher than, levels at Station 2-R, yet lower than those at Stations 7a-R and 13-R. Station 5-1 sediments contained mean TAE concentrations from 0-091 to 0.57 Itg g- ~ dry weight. TAE concentrations in sediments increased from the 0- 1 g~gg - ~ dr}' weight levels observed during the two pre-drilling cruises to levels o f 0 - 4 / l g g - ~ dry weight during the May, 1982 (cruise M-4) and subsequent surveys. This trend in increasing hydrocarbon levels coincided with initiation of drilling operations. However, concentrations oi" total aromatic equivalents did not decrease after cessation of drilling, but remained fairly constant, with mean concentrations typically between 0-3 and 0.4 l~g g- ~ dry weight, during the second and third years of the study ([Fig. 4). One-way A N O V A s for log-transformed TAE in Station 5-1 sediments indicated significant differences I p < 0-001) among cruise means. The results from a Duncan multiple range test indicated that concentration means from cruises M-I through M-3 were different from means for cruises M-4 through M-12. Mean TAE concentrations in sediments from the other near-rig stations (5-18 and 5-28) generally were within the same range as concentrations in Station 5-1 sediments, although no corresponding increases were apparent in the Station 518 and 5-28 sediments during drilling. Statistically significant differences among means for Stations 5-18 and 5-28 sediments also were detected: however, multiple range test results could not distinguish between groupings.

Georges Bank monitoring pro~rarn

5l

Composite samples (homogenized aliquots from three replicates) col* lected from Station 5-1 during cruises M-1 through M-4 and analyzed by F I D - G C contained total hydrocarbon concentrations from 0-27 and 0- 17/2g g- t dry weight during the pre-drilling period (cruises M- 1 and M-2, respectively) to 0.20 to 2.6.ug g-~ d ~ weight during drilling (cruises M-3 and M-4. respectively). The total hydrocarbon concentrations measured for the cruise M-4 composite sample was slightly higher than the 0.5 to 1.6~Lgg-t dry weight values reported by Boehm (1984) for Station 5 sediments collected in 1977. Sediment extracts from post-drilling cruises M-5 through M-9 analyzed by F I D - G C were from single replicate samples ~hich were selected for further analyses (i.e. F I D - G C and GC/MS) based on the results from the UV fluorescence screen, and were not necessarily representative of all three replicates collected at the station. The total hydrocarbon concentrations for individual samples from cruises M-5 through M-9 ranged from 0-04 to 1.5 Ftg g- 1 dry weight. These values could not be used to assess temporal trends in sediment hydrocarbon levels due to the considerable variability among replicate samples. Chromatograms of sample extracts from Station 5-1 suggested that increases in TAE concentrations during drilling were associated with deposition of *petroleum" hydrocarbons. Sediment extracts from pre-drilling cruises (M-I) did not contain a UCM or a homologous series of ~zalkanes, and the higher boiling point alkanes in the F t fraction with an odd-carbon predominance (odd:even ratio of 2.6) reflected significant contributions from terrestrial plant waxes (Fig. 6). The F~ fractions contained a predominance of biogenic alcohols with no detectable PAHs. In contrast. extracts from Station 5-1 sediments collected during drilling operations (cruises M-3 and M-4) contained a bimodal grouping of n-alkanes, with a repeating series from C ~ to C_,o and from C:~ to C3~, with a lowered predominance of odd-numbered carbon n-alkanes yielding odd:even ratios of 2.2 and 1-6, respectively. Additionally, the M-4 sample contained a large UCM within the KOVAT index range of 2100 to 3500 centered at C2~ (Fig. 6). The F, fraction of the cruise M-4 sample analyzed by GC, MS contained several alkyl-substituted PAHs. including Ct-, Cz-, and C gsubstituted naphthalenes and C~-, C,-, and C~-substituted phenanthrenes in nanogram per gram dry weight levels, with a total PAH concentration of 28 ng,,- ~ dry weight (Table 5). The abundance and composition of alkyl-substituted PAHs, the lowered odd:even ratio of n-alkanes, and the predominant UCM, as well as the measured increase in TAE concentrations, provided evidence of petroleum hydrocarbons in the near-rig sediments (e.g. Farrington & Meyers, 1975). Deposition of either small amounts of drilling-related discharges, such as drilling fluids containing a diesel fluid additive or cuttings with formation

Charles R. Phillips et al.

52

o

+j

oo

o A

o

.l++J++ ... _.,++,

_ _

~

o°

+,.J

t

,

-

,IL

B

o

m

~

=0

o

-....

oL n o ~

',,,.--- L

Fig, 6.

"+

~IL.~

I

L

.

+ldi'

+ '/'k

cn

;]/J

-

"

- i,i,u~

ll_t

t.

~

FID--gas chromatograms of F, fractions of Station 5-1 sediments during cruises M-1, M-3, M-4, and M-8.

53

Georges Bank monitoring program

TABLE 5

Results from G C M S Analysis of Sediment Extract: Station 5-1, Cruise M-4, Aromatic (F_,) Fraction {Concentrations in ng g-t Dr) Weightl KO IA T Index

Compound identification

Concentration (ngg i dr3. ,'e~¢ht)

1288 1305 1375 t399 1414 1417 1482 1510 526 542 559 577 588 595 629 1646 1667 1676 1700 1730 1746 1774 1857 1903 1914 1968 2030 2055 2066 2107 2133 2232 2289 2494 2882

2-methylnaphthalene 1-methylnaphthalene biphenyl 2,6-dimethylnaphthalene dimethylnaphthalene dimethylnaphthalene propylnaphthalene or Methylbiphenyl isopropylnaphthalene dibenzofuran trimethylnaphthalene 2,3,5-trimethylnaphthalene fluorene I H-fluorcne or 9H-fluorene trimethylnaphthalene mcthyldibcnzofuran mcthyldibcnzofuran butylnaphthalene Cs-naphthalcne mcthyl 9H-fluorene Cs-naphthalene dibenzothiophene phenanthrcne met hyldibenzot hiophene methylphenanthrene methylphenanthrene 1,2-benzenedicarboxylic acid, ester dimethylphcnanthrenc dimethylphenanthrene dimethylphenanthrene pyrenc 3-ring PAH C a-phenan t h rene methylpyrene 4-ring PAH perylene

1.69 1-18 0-46 1.35 1.20 0.58 0-23 1-24 0-94 0.4 I 0.24 0-85 0-24 0.19 0.26 0-26 0.43 0.67 089 0-61 0.67 3.46 0.34 0.18 0-87 0-69 0-89 1-62 0.4 I 1.46 0-68 0.37 0-33 0.91 0.89

54

Charles R. Phillips et at.

derived hydrocarbons, or particulate coal and'or tar specks from sources unrelated to drilling could account for these changes in the TAE concentrations. One sample of the spent drilling fluids analyzed by Payne et al. ~1982) contained residues of diesel oil and an oil-soluble, anionic, surface active agent ('free-pipe': Table 1), with a total hydrocarbon concentration of 480 mg I- t. Petroleum hydrocarbons were indicated by the series of evenly repeating n-alkanes in the Cto to Czs range (Fig. 7), with an odd:even nalkane ratio value of 0.94, and a moderate UCM comprising 55% of the total F~ concentration. Additionally, F I D - G C and G C M S analysis of the F, fraction confirmed the presence of numerous alkyl-substituted monocyclic and polynuclear aromatic compounds in the KOVAT Index range of 993 to 2058, with concentrations of individual compounds from several hundred to several thousand nanograms per gram {Table 6). Comparisons between chromatograms of the drilling fluid extracts and those of the Station 5-1 sediment samples from cruise M-4 illustrate similar n-alkane patterns and a similar relative position of the UCM. These chromatographic features (Figs 6 and 7), along with the compositions and ratios of the individual di- and tri-cyclic aromatic compounds (Tables 5 and 6) suggest that the drilling discharges may have contributed to the hydrocarbon signal in the near-rig bottom sediments during cruises M-3 and M-4. The absence of mono-cyclic aromatic compounds, which are abundant in the drilling fluid extracts, in the Station 5-I sediments can be attributed to dissolution due to the higher solubility of these compounds in seawater compared to the di- and tri-cyclic aromatic compounds. Alternatively, Tripp et al. (1981) have reported that unburned coal extracts produce chromatographic features similar to those from a light crude oil and fuel oil, and further suggested that particulate coal could comprise a quantitatively significant source of hydrocarbons to Georges Bank sediments. The number o[" analyses performed during this study were not sufficient to evaluate the magnitude of possible contributions either by particulate coal or formation-derived petroleum to the sediment hydrocarbon concentrations. Therefore, while the data indicated the presence of "petroleum' hydrocarbons in near-rig sediments, it was not possible to differentiate contributions from all potential input sources. Sediments at Station 5-1 during post-drilling surveys, or at the near-rig Station 5-18, did not contain petrogenic materials similar to those observed during cruise M-4. One of the three replicate samples from Station 5-28 during cruise M-3 contained a number of alkyl-substituted PAHs whose selected ion monitoring profiles matched closely with those of drilling fluids from the 5,000 ft well depth, In particular, matches were apparent for compounds in the molecular weight range of biphenyl and acenaphthalene

Georges Bank monitoring program

55

¢..;

C ¢,

E.

l

.

¢

O00Z

O08L

3NV~A~d

"-d

tr~

O

E.~ o

t.-.-

3NVISI~d

O09t

L69L

t..

£L~t

c._ O

~t¢

r"

I

~L~

OOW

",.a

£t£t L8~'L r"

O00L

5r ",,0

c~ r-: Lr.

.~ t--. .-.

c..,.

56

Charles R. Phillips et al.

TABLE 6 Results from Analysis of the F, Fraction of a 5,00Oft Drilling Fluid Sample Containing Diesel Oil and 'Free Pipe" (Concentrations in gg liter: Quantitation by FID--GC) KO ~"A T lnde.v

851 860 888 936 967 993 1050 1053 1057 1064 1076 1083 103

I 16 135

144 156 163 177 184

194 1209 1260 1287

1304 1313

1340 1387 1397 1413 1432 1447 1481 1498 1520 1541

1557 1573 1664 1697 1726 1741 1768

Compound identification

Concentration (/.~g liter- ~)

ethylbenzene m- and or p-xylene o-xylene C3-benzene C3-benzene C3-benzene Ca-benzene butylbenzene methyl-3,5-dimethylbenzene met hylpropylbenzene Ca-benzene Ca-benzene Ca-benzene Ca-benzene 2,3-dihydromethylindene 2,3-dihydromethylindene tet rahydronaphthalene Cs-benzenc naphthalene 2,3-dihydrodimethylindene 2,3-dihyd rodimet hylindene Cs-benzene 1,2,3,4-tetrahydromethylnaphthalene 2-methylnaphthalene 1-met hylnapht halene 1,2,3,4-tet rahydrodimet hylnaphthalene 1.2,3,4-tetrahydrodimet hylnaphthalene dimethylnaphthalene dimethylnaphthalene dimethylnapht halene dimethylnaphthalene dimethylnaphthalene methylbiphenyl C3-naphthalene C3-naphthalene C3-napht halene C3-naphthalene fluorene Ca-naphthalene methylfluorene C.-biphenyl dibenzot hiophene phenanthrene

252 115 116 35.2 660 152 216 79-9 123 160 487 345 519 224 446 659 357 553 408 600 367 290 1250 2900 1640 1060 274 2290 3420 1220 965 879 1360 1220 632 34-9 2620 593 498 587 268 205 634

57

GeorRes Bank monitorin~ program TABLE 6--contd.

KO V,4 T Index

Compound identification

Concentration (l~tgliter- 1)

1842 1862 1884 1889 t908 1942 2004

met hyldibenzothiophene met hyldibenzot hiophene methylphenanthrene methylphenanthrene methylphenanthrene dimethylnapht hol 2.3- B)thiophene dimethylphenanthrene

306 l2 l 468 294 306 t 62 263

through methylperylene. The absence of clear matches for lower molecular weight compounds from Cz-benzene through C4-benzene probably was due to preferential solubilization of these compounds during settling of drilling fluid particles. This station was 6 km from the drill site, and the sediment sample was collected 15 days following a discharge of 21 barrels of spent drilling fluids. The elevated TAE concentration and presence of PAHs was apparent at Station 5-28 in only one of the three replicates during February, but not during the subsequent May survey. Chromatograms of cruise M-8 sediment extracts, which were typical of the profiles of post-drilling sediment hydrocarbons at near-rig stations, contained a series of n-alkanes with an odd carbon predominance in the /'1C23 to tlC31 range with no UCM (Fig. 6), and few resolved compounds in the F 2 fraction. Chromatographic analyses of other selected sediment extracts, both from Station 5-1 and from Stations 5-18 and 5-28, exhibited varying contributions from both biogenic and petrogenic sources that were not consistent among replicate samples. Trace amounts of naphthalenes (1 n= , , ,~. , - i ) and phenanthrenes (4-6 ng g- ~) were present in composited sediments from Station 5-1 during cruise M-5, immediately following drilling; however, the majority of compounds were biogenic alcohols and polyunsaturated alkenes. The presence of PAHs in sub-nanogram per gram levels in other near-rig sediments typically was sporadic and not homogenous among replicate samples. These same features were also characteristic of the pre-drilling sediment hydrocarbons at Station 5 (Boehm, 1984). H y d r o c a r b o n s in tissues

Tissues of the two Arctica islandica samples collected from the near-rig site before drilling contained total aromatic equivalents from 0.05 to 0-29 l~g g- 2 dry weight (Table 7). During and after drilling operations, TAE concentrations ranged from 0.02 to 4.5 lLg g-~ dry weight. Tissue samples analyzed by F I D - G C contained total aromatic (F_,) and total saturated

Charles R. Phillips

58

T A B L E

Concentrations

of Total

Aromatic

7

Equivalents

A r o m a t i c s (t-2-), a n d T o t a l H y d r o c a r b o n s

(THC)

e t al.

(TAE)

and

Total

in W h o l e T i s s u e s o f

Saturates

(fl), Total

Arctica islandica

(Con-

c e n t r a t i o n s in u g g - ~ D r y W e i g h t )

Cruise

Date

Station 5 TA E f l

M-I

( J u l y , 1981)

M-2

(November,

M-3

(February.

1981) 1982)

( M a y , 1982)

(February,

M-8

( M a y , 1983)

M-9

1983)

(July, 1983)

(November,

M-II

(February.

M-12

( J u n e , 1984)

NA = No

analysis.

1983) 1984)

NA

NA

--

--

NA

NA

--

--

NA

26

26

NA

--

--

NA

NA

--

--

NA

0"30

4.0

25

29

0"005

--

--

NA

0.08

0

4.2

0

5.3

5.3

0-10

--

--

NA

0.12

--

--

NA

1.0 --

7.5 --

1.0

1.0

3.3

85 NA

2-6

2.0 5.9

--

--

NA

0-88

--

--

NA

0-46

--

--

NA

0"65

--

--

NA

56 --

12

18

--

NA

I-0

--

--

NA

1"5

--

--

NA

0-53

--

--

NA

0"52

--

--

NA

0.99

---

--

NA

0.09

--

--

NA

0.17

--

--

NA

NA

--

--

NA

0-07

--

--

NA

0.31

--

--

NA

0-24

--

--

NA

0.62

--

--

NA

0-22

--

--

NA

0-02

--

--

NA

0.19

--

--

NA

0.03

--

--

NA

0-28

9-6

23

33

0"15

--

--

NA

4-5

28

58

86

3"3

--

--

NA

4.5

--

--

NA

0.52

9.4

31

40

3.3 M-10

--

NA

0-73

M-7

--

NA

--

0.34 1982)

THC

--

1.6

(November,

NA

)2-

--

I "0

M-6

TA E f l

--

0-08

(July. 1982)

THC

0-29

0-56 M-5

f2

0.05

0.06 M--4

Station I-R

19

20

1-9

0.96

17

18

38

--

1.4

--

NA

1-1

--

--

NA

NA

--

--

NA

NA

--

--

NA

3.5

--

--

NA

0-84

--

--

NA

3-9

26

41

67

--

--

NA

1.6

Georees Bank monitorin~ program

59

(F~) hydrocarbon concentrations from 10 to 58 tLgg-~ dry weight and from < 1,0 to 28 #g g- t dry weight, respectively. Neither of the pre-drilling A. islandica samples was analyzed by F I D - G C or GC'MS. TAE concentrations in samples of individual and composite whole A. islandica tissue were higher during the third year of sampling than during the first two years, although the reasons for this increase were not immediately apparent. The A. islandica samples collected during cruises M-9 through M-12 and analyzed by F I D - G C and GC,'MS contained primarily biogenic aldehydes, alcohols, and normal alkanes: PAHs were not detected. Arctica ishmdica samples collected from the near-rig site immediately following drilling (cruise M-5) also contained numerous aIiphatic aldehydes, f~ltty acids and sterols. Concentrations of the four resolved aromatic compounds, o-xylene, cumene, phenanthrene and fluoranthene, were low: phenanthrene and fluoranthene were present at < "~n,, ~,- t dry weight and 6 ng ~,,,- t dry, wei~ht.~ respectively. The low aromatic hydrocarbon, concentrations and absence of alkyl-substituted PAHs suggest that drilling discharges did not affect hydrocarbon concentrations in A. isl,mdica at near-rig sites. All ,4. Mandica samples from Station I-R were collected after drilling: no samples were obtained prior to. or during, drilling. Tissues of A. islandica from Station I-R contained TAE concentrations from 0.005 to 3.31~gg-L dry weight (Table 7). Selected tissues analyzed by F I D - G C contained from 17 to 31 .=,u,,,,- t dry, wei,,ht= total aromatic hydrocarbons and from 0.96 to 9.6 ~L,gg- t dry weight total saturated hydrocarbons. Analyses of whole individual tissue extracts and composite foot tissue and gill tissue showed that essentially all of the components represented in the whole tissue extract could be accounted for in the separate tissue types, although the majority of resolved compounds apparently were associated with the gilt tissue. All extracts show a clear odd-carbon predominance in the F t fraction. indicating that the majority of components were biogenic. Furthermore. the majority of resolved components in the F, fraction were biogenic alcohols and sterols. Samples from two separate cruises contained trace amounts of several PAHs: however, the absence of alkyl-substituted PAHs indicated that drillin~ dischar,,es= were not a primary source of fossil-fuel hydrocarbons. Other sources, such as atmospheric transport of pyrolytic PAHs (Pancirov & Brown, 1977: Boehm & Farrington, 1984), may have contributed to the observed hydrocarbon tissue burdens. No evidence of ingestion and accumulation of tar specks by .4. islandica from Station 1-R was observed during this study. Seasonal fluctuations of hydrocarbons in macrofaunal tissue samples were not observed during the previous study (Alpert, 1978). Furthermore, no relationship between the quantities and composition of hydrocarbons in

60

Charles R. Phillips

et al.

sediments and hydrocarbons in tissues was observed. Marked qualitative and quantitative intra-specific differences in tissue burdens were apparent. Tissues of Arctica islandica contained relatively high concentrations of petroleum hydrocarbons, with concentrations of total n-alkanes up to 12.8 #g g- t dry weight and total hydrocarbons from 64 ~Lgg- 1 dry weight to 130vgg- t dry weight (Boehm et al., 1979). The source of the petroleum hydrocarbons was attributed primarily to small, but ubiquitous, tar specks which may have originated from crude oil sludge discharged from tankers during ballast pumping operations (Boehm et al., 1979) or from tanker spills (Hoffman & Quinn, 1979: Hoffman et al., 1979). T r a c e metals in tissues

In general, trace metal concentrations were consistently low in A. islandica from Station 5 (Table 8). In particular, the barium concentrations for both the individual and composite tissue samples ranged from 0-39 to 1.8 #g g- t dry weight. Barium was not quantified in ,4. islandica tissues during the previous study (Alpert, 1978): therefore, no data are available to assess seasonal or year-to-year variability. Observed differences between the second and third year concentrations may be due to natural variability in concentrations of barium in phytoplankton, radiolarians, and zooplankton, which comprise a major portion of the diet of filter feeding bivalves and may vary over several orders of magnitude (Martin & Knauer, 1973). Similar differences between the second and third year (post-drilling) barium levels were observed in tissues from Station I-R, approximately 50kin upcurrent from the drill site. No relationship between sediment barium levels, reported by Bothner et al. (1984, 1985), and tissue concentrations was apparent. Therefore, it is unlikely that drilling operations had any significant effect on tissue barium levels in A. islapzdica at the drilling site. Concentrations of other metals measured during this study generally were consistent with values presented by Alpert (1978) for pre-drilling metal concentrations in A. islandica tissue from the Georges Bank, with the exception of the slightly higher chromium, lead, copper, and zinc concentrations measured during this study (Table 8). Alpert (1978) suggested that elemental compositions of the suspended particulates and, in turn, metal levels in filter feeding organisms, reflect: (1) proximity to terrestrial sources for metals, such as cadmium and lead: (2) influences from episodic intrusions of slope waters with associated elevated metal levels: (3) spatial and seasonal variations in the relative influence from the confluence of the gulf of Maine and Georges Bank gyres on suspended particulate concentrations and (4) seasonal fluctuations in concentrations of suspended sediments. Natural variability in suspended particulate trace metal loads may

61

Georees Bank monitoring pro erarn TABLE 8 Trace Metal Concentrations in VChole .4. islandicu Tissues from Stations 5 and l - g Cruise Date Cd Station 5 M-I (78t) M-2 (11 81) M-3 (2 82) M-4 (5.82) M-5 (7 82) M-6 (11 82) M-7 (283) M-8 (5,83) M-9 (7 83) M-10 111,831 M-II (2 84) M-12 (684) Statiott I-R M-I (781} M - 2 (11,81) M-3 t282) M - 4 1582) M-5 (7,82) M-6 (tl82) M-7 (283) M-8 15/83) M-9 (783) M-10 (11/83) M-II 1284) M.-12 (6841

Concentrations ( ug g-~ dry wet~.t,t) Cu Ni Ph Zn Ba

Cr

3.95 2.09 . . . 4.61 1.52 3.12 1.79 3.57 1.31 361 257 .

.

4.72 466

5.54 17-8 . . . 5.15 29.1 4.75 19.9 II.0 12.7 6-85 225

.

.

1.61 402

.

.

6-97 3.20

.

.

.

.

.

.

.

1.24 1-92 2.33 1-78 3.34 . . 0.458 2.71

. .

. .

.

9-10 13.6

.

.

. .

0-355 1.22 0-78 1.30 1.80 . . 2.19 1.51

. .

.

9.86 7.28<0.161 4.25 11.2 0.167 4.23 I0-2 0.157 4.19 1 4 . 1 0.156 9.53 9.52 2.00 . . . . . 7.46 17.3 1.14 9-40 7.32 3.07

0.61 0-66

.

. .

.

0-034

0-98 0-344 0-276 0-32

0-058 0.079 0.004 0048

055 4-0

0-035 0050

2-6 0-65

0.067 0.031

0-258 0.136 0.016 0-963 1.02

0.005 0.009 0008 0.009 0-012

1.31 1.21

0.025 0.004

.

.

. .

0.35

.

.

. .

I-2 03~

.

.

Hg

.

128 159

.

. .

.

133 172

.

.

. .

150 164 95.1 97.4

7.86 4.70

.

0.40 . 1.2 1.8 I-a 10

.

.

.

.

107 .

0.799 402

23.7 22.4

. .

.

155 257

.

4.45 1.80

.

.

5-24 116

4-49 . 2.3t 1.91 0-247 0~103

V

.

. .

90.6 76-1 71-5 109 91-5 . . 123 97.3

. .

. .

1.88 0.258 NA 0-544 0-294 . . 0-091 0-472

account for the one- to two-fold differences in tissue concentrations of some trace metals observed during this and previous studies. Consistent seasonal patterns in the concentrations of individual trace metals are not evident when comparing the data from cruises M-9 through M-12 with data from cruises M-I through M-8. However. data from some seasons (e.g. winter, 1982 and fall, 1981) were not available: thus. the continuity of year-to-year comparisons of metal levels is somewhat limited. Inherent variability is an additional factor that inferferes with interpretation of trace metal concentrations in bivalve tissues (National Research Council, 1980). This variability may be related to the size and sex of the animal, sexual maturity, and feeding patterns (National Research Council, 1980). Alpert (1978) concluded from experiments with A. islandica that concentrations of trace metals in tissues varied considerably for pooled

62

Charles R. Phillips et al.

samples comprising less than 18 organisms. Unfortunately. sufficient numbers of A. islandica were not collected during this study to pool 18 or more individuals. Maximum pool sizes during the study typically were limited to four individuals. Coefficients of variation for metal analyses in organisms collected during cruise M-9 and analyzed individually ranged from 9% (zinc) to 93% (barium). Consequently, intraspecies variability may obscure some of the seasonal patterns in trace metal concentrations in ,4. islandica tissue. Metal concentrations in A. islandica tissue samples collected at Station I-R were consistently low, and no changes in tissue burdens over time were apparent. Furthermore, with the exception of the relatively higher Pb values, metal levels in various tissues one to two years after drilling were comparable to concentrations measured during, and immediately after, drilling (this study) and prior to drilling (Alpert, 1978). Differences in tissue lead concentrations may reflect differences in sample processing techniques. Alpert (1978) dissected and analyzed organs separately; during this study, entire soft parts (with the exception of the hepatopancreas from cruise M- 1 through M-8 samples) were analyzed. Metal concentrations in tissues from Station I-R typically were lower than values for Station 5 tisst,e. However. the consistently low trace metal concentrations and absence of any apparent temporal trends in organisms collected near the drill site suggest that differences between near-rig and regional stations were related to factors other than drilling activities. The concentrations of trace metals in sediments at both Station I-R and Station 5 were relatively low (Bothner et al., 1982. 1984), and Payne et al. (1983) found no consistent trends between tissue metal concentrations and sediment metal concentrations. Therefore, slight differences in sediment metal concentrations were probably not responsible for the observed differences in tissue metal concentrations. Site-specific differences in suspended particulate material concentrations, plankton productivity, and the elemental composition of suspended particulate materials, may contribute to the observed differences in metal concentrations (Alpert. 1978).

DISCUSSION Despite measured increases in TAE concentrations and the deposition of fossil-fuel derived PAHs in near-rig sediments during drilling, the drilling discharges did not appear to significantly alter the hydrocarbon geochemistry at the site. Both the total hydrocarbons and the concentrations of individual and total PAHs in Station 5 sediments were consistent with concentrations reported from earlier studies (Farrington et al., 1977;

Georges Bank monitoring prod.ram

63

Farrington & Tripp, 1977: Boehm, 1984; Boehm & Farrington, 1984). The fossil fuel pollution index (Boehm & Farrington, 1984) value for Station 5-1 sediments from cruise M-4 was 0-54 and essentially equal to values calculated for pre-drilling sediments from this site. Additionally, the materials present in Station 5-1 sediments during cruise M-4 which contributed to the petroleum hydrocarbon signal did not persist at this site after drilling stopped. The absence of a decline in TAE concentrations is puzzling, although it is possible that naturally-occurring fluorescing compounds which contributed to the UV,,fluorescence signal (e.g., Hoffman et al., 1979) were present at levels below the detection limits of GO and GC/MS. While the presence of PAHs in the sediments at the regional stations suggests either pyrolytic or fossil fuel sources of hydrocarbons, the generally low levels of alkyl-substituted aromatic compounds and the absence of an evenly repeating series ofn-alkanes in the C~o to C tQ range characteristic of the spent drilling fluids suggest that the drilling discharges were not a major source of petroleum hydrocarbons to these depositional environments. During previous studies, presence of several PAHs in concentrations from 1.0ngg-t to 100ngg-t dry weight suggested aeolian transport and deposition of particulate PAHs from incomplete pyrolysis of fossil fuels a n d o r long-range transport of hydrocarbons associated with sewage sludge or dredged material disposal operations (Boehm, 1983; Boehm & Farrington, 1984). Fine-grained sediments from depositional areas contained relatively high concentrations of" PAHs, derived primarily from combustion sources. Combustion PAHs were associated with small soot particles which were transported and eventually deposited with other silt clay sized particles. Sediments from non-depositional areas generally conrained lower PAH concentrations with smaller amounts of combustion PAHs. but with relatively greater contribution from non-combusted, petroleum sources (Boehm & Farrington, 1984). Petroleum sources of PAHs were implied by high levels of alkyl-substituted compounds, particularly naphthalenes and phenanthrenes, relative to those of the parent (unsubstituted) compounds. Variability in TAE and total hydrocarbon concentrations among replicate sediment samples also obscures trends in hydrocarbon values (Alpert, 1978: Boehm et al., 1979; Hoffman et al., 1979). Hoffman et al. (1979) suggested that the presence of minute tar specks, mixed non-homogeneously in sediment samples, accounted for poor reproducibility in total hydrocarbon concentration measurements: heterogeneity would also result in apparent increases in total hydrocarbons of two orders of magnitude and coefficients of variation of 55°'0 for triplicate analyses of a single sample. Evidence of replicate variability due to the presence of tar specks was observed during this study in sediments collected from Stations 5-I and 5-18 during cruise

6a,

Charles R. Phillips et al.

M-9. Single replicate samples from both stations contained relatively high TAE concentrations (0-64/ag g- t and 0-99 gg g- t, respectively). Chromatograms of both F t fractions were virtually identical, with similar n-alkane patterns and UCM (Fig. 8), yet were different from the chromatograms of drilling fluids or the Station 5-1 sediments from cruise M-4. High single replicate concentrations resulted in greater apparent temporal fluctuations in mean TAE concentrations relative to those observed at the control site. These unusually high replicate values probably reflect the non-uniform distribution of weathered tar specks in bottom sediments (e.g., Boehm, 1984: Boehm & Farrington, 1984). There were no indications of any seasonal fluctuations in biogenic inputs that would substantially influence the observed aromatic hydrocarbon concentrations at these stations. The lack of a significant accumulation of petroleum hydrocarbons in

8 I 8

8

7,

A

_! ~,

o°

8

8

8

g o

~

B

Fig. 8.

F l D - g a s chromatograms of the F, fractions of sediments from (A) Station 5-1 and (B) Station 5-18 during cruise M-9.

Georges Bank monitoring program

65

sediments near the drill rig is not surprising considering the relatively small quantity of hydrocarbons discharged and the strong bottom currents responsible for scouring fine sediments from the shallow areas of the Banks. It is likely that hydrocarbons associated with the fine-grained particles (< 63 um diameter) which comprised > 9 0 % of the drilling fluid discharges were resuspended and transported rapidly from the drill site. Bottom currents required to resuspend fine-grained sediments are frequently exceeded at the site (Butman et al.. 1982: Bothner et al., 1985). In fact, Bothner et al. 11985J calculated a "half-life" of less than 0.5 years for the barite inventory in bottom sediments derived from drilling discharges. Half-lives for associated hydrocarbons may be even shorter due to the greater solubility of petroleum hydrocarbons (Delaune et at., 1980), particularly the unsubstituted one- and two-ring aromatics which were present in significant concentrations in the diesel fuel additives of some drilling fluid discharges. The results from the present study support Boehm's (1984) contention that pulsed inputs of sediment pollutants, such as petroleum hydrocarbons associated with fine grained particles, would not accumulate in shallow, erosional environments on Georges Bank, but would disperse within one year following deposition. The contributions of cuttings discharges to hydrocarbon inputs were not determined during this study, as no representive samples could be obtained tbr analysis. Nevertheless, cuttings particles may transport small amounts of drill muds or formation-derived hydrocarbons which are not removed by washing prior to discharge (Neffet al.. 1985). Due to the typically larger sizes of cuttings particles relative to drill muds, cuttings would be less susceptible to bottom current scour and more resistant to transport from the drill site. Horizontal dispersion of cuttings may be restricted to a small area (within 1,000 m) adjacent to the discharge point (National Research Council, 1983), although cuttings may be mixed vertically into the sediment column. Concentrations and spatial patterns of sediment hydrocarbons observed during this study reflect sediment grain size, bottom depths, and sediment transport processes. Results from previous studies and monitoring programs have demonstrated that appreciable accumulation of drilling discharges, and accompanying changes in geochemical parameters, are more likely in areas of greater bottom depths and weaker bottom stresses (National Research Council, 1983: Boesch et al., 1985). For example, Boothe & Presley (1985) concluded that the distribution of excess barium associated with drilling fluids discharged from a series of exploratory and production operations in the Gulf of Mexico was related to bottom depth (as an indicator of the susceptibility to particle resuspension and transport) and the amounts of barium discharged. Thus, the greatest barium excess

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Charles R. Phillips et al.

occurred at the deeper sites where weak bottom shear stresses permit deposition and accumulation of barium-enriched fine particles. At the shallower sites, > 94% of the bulk barium discharge apparently was transported beyond 3.000m from the site (the horizontal limit of the station array). Boothe & Presley (1985) also concluded that the distributions of hydrocarbons in bottom sediments around the drill rigs were patchy and did not coincide with spatial patterns for other drilling fluid components, possibly due to solubilization of aromatic hydrocarbons. At one site where diesel fuel was used as a drilling fluid additive, elevated total hydrocarbon concentrations were apparent in sediments 125 m from the drill rig, and the hydrocarbons appeared to be associated with discharged cuttings. In general, hydrocarbon concentrations were not significantly correlated with barium, organic carbon or inorganic carbon concentrations, suggesting that the fates of the hydrocarbon components may be affected by processes which are different from those affecting other drilling fluid components. Similarly, at the site of exploratory drilling operations in the midAtlantic Bight, elevated concentrations of weak acid leachable barium were apparent in bottom sediments within a two-mile radius of a drill rig (Mariani et al., 1980). Bottom depths were 190m, with currents typically less than 3 0 c m s - t and not affected strongly by storm agitation (Ayers et al., 1980); the area is considered a depositional regime (Mariani et al., 1980). A cuttings pile accumulated in the immediate vicinity of the drill rig, but barium was the only related element detected in bottom sediments. Petroleum hydrocarbon concentrations were not measured, although no statistical differences between pre- and post-drilling quantities of extractable oil and grease (gravimetric) were detected. In contrast, no cuttings pile formed when materials from an exploratory well in Lower Cook Inlet (Alaska) were discharged at a site with a water depth of 62m and mean maximum flood and tidal current velocities of 52 cm s- ~ and 42 cm s- t, respectively (Houghton et al., 1980). The heavier cuttings particles were mixed down into the sediment layer, reaching depths of 12 cm three months after deposition. The maximum contribution from cuttings to any sediment samples was 3% by weight and occurred 100 m from the discharge. Slightly elevated barium levels were detected only in sediments near the discharge, suggesting that currents and sediments abrasion dispersed drilling fluid particles, especially those adhering to cuttings. Highly elevated concentrations of petroleum hydrocarbons, up to 10,000 times above background, have been measured in bottom sediments within 250 m of platforms in the North Sea (Davies et al., 1984; Grahl-Nielson et al., 1980). Discharges from these platforms of oil-based muds containing 6% to 17% diesel oil by weight resulted in an average 92 tons ofoil per well

Georges Bank monitoring program

67

or a total input of approximately 7,000 tons of oil to the marine environment. Hydrocarbon concentrations decreased rapidly ~ith increased distance, reaching background concentrations at 2,000 to 3.000 m from the platform. The slope of the concentration gradient was related to the strength of sediment transport processes (Davies et al., 1984). Subsequent dispersion of discharged materials may have responded to strong tidal and storm surges: however, Davies et al. reported that oiled particles appeared very cohesive and possibly resistant to transport. The zone of highly elevated hydrocarbon concentrations corresponded to areas of highly modified biological communities. The results from these and other studies indicate that long-term accumulation of pollutants associated with routine discharges of water-based drilling fluids and cuttings are unlikely in shallow, erosional environments such as Georges Bank (Boesch et al., 1985). Accumulation of materials from operational discharges could occur in depositional areas such as the Mud Patch. However, with the relatively small amount of hydrocarbons discharged, and rapid and effective mixing of particulates with natural sediments, the signal from the discharges would be very weak and difficult to detect above background concentrations. Likewise, the absence of detectable bioaccumulation of hydrocarbons and trace metals in tissues is consistent with the observed minimal enrichment due to drilling discharges. However, patterns in the distribution and abundance o1" hydrocarbons in organisms were difficult to discern during this study due to the Low numbers of samples collected and analyzed. Arctica islandica were not collected consistently at any site throughout the duration of the study. Furthermore, only two ,4. islandica were collected during the pre-drilling cruises, and neither sample was analyzed by F I D GC. The small sample size and the large intra-specific variability (Boehm et al., 1979) make rigorous comparisons among samples collected during and after drilling operations tenuous. It is unlikely that short-term exposures to the concentrations of hydrocarbons observed in the near-rig sediments would be toxic to benthic fauna (e.g. Neff & Anderson, 1981). Furthermore, Maciolek-Blake et al. (1984) detected no impacts to the biological community at near-rig stations attributable to drilling discharges. No indications of bioaccumulation of discharge-related hydrocarbons in Arctica islandica tissues were observed during the study. Whether or not individual A. islandica ingested petroleum-contaminated particles and later excreted or released the hydrocarbons to ambient waters is problematic. Regardless, no long-term trends in hydrocarbon tissue burdens or evidence of petroleum hydrocarbon contamination were observed in organisms from the drill site. Bioavailability of sediment-bound hydrocarbons to bivalves varies as a

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Charles R. Phillips et al.

function of their persistence and the feeding behavior of individual species (Capuzzo, 1985). For short exposure periods of days to weeks, hydrocarbon uptake is kinetically regulated by dissolution and exposure to dissolved components, whereas equilibrium-based uptake mechanisms are more important for longer exposures of months to ,,'ears (Capuzzo, 1985). There have been no published laboratory investigations on uptake of petroleum hydrocarbons from diesel-treated drilling fluids (Neff, 1985). Bioconcentration factors for petroleum hydrocarbons by marine organisms from sediments or detrital materials are typically between one and two (National Research Council, 1983), although Augenfeld et al. (1982) reported bioconcentration factors from sediments of 7.9 to 12 for phenanthrene and chrysene, respectively, for the clam M a c o m a inquinata. However. the low concentrations of hydrocarbons in water-based drilling fluids, such as those used for exploratory drilling on Georges Bank, and the short residence times in shallow, erosional environments suggest that significant accumulation of hydrocarbons from bottom sediments is unlikely. Results from limited field and laboratory studies suggest that bioaccumulation of metals from drilling fluids is relatively low (National Research Council. 1983). Metals from spent drilling fluids are typically in the tbrm of insoluble sulfides, or are adsorbed onto particulates, and have a much lower bioavailability than dissolved metal ions (Neff et al., 1976; Capuzzo, 1985). Limited field data have been collected previously to assess availability or bioaccumulation of trace metals from drilling discharges. Mariani et al. (1980) reported significantly higher post-drilling as compared to pre-drilling concentrations of barium in tissues from pooled samples of molluscs, brittle stars, and polychaetes, and chromium in polychaetes. Higher barium concentrations in molluscs were apparent in samples throughout an area within a one mile radius of the site, with the highest concentrations from samples near the site. Regardless. the spatial patterns in tissue levels did not correspond to patterns in sediment barium levels. The ability to discern spatial and seasonal trends in trace metal concentrations in organisms was limited during this study by the variable success rate or" collecting specimens during each season and in collecting adequate numbers of samples at each station. Due to the inherent variability in trace metal levels in bivalves (National Research Council, 1980), collection of single specimens during one or two seasons is inadequate for characterizing large-scale spatial or long-term temporal trends in tissue metal burdens, and precludes any correlations between drilling activities and tissue levels. Problems collecting adequate tissue samples suggest that the concept of sampling target organisms may not be practical as a method of assessing bioaccumulation. Use of transplanted or caged bivalves placed at several locations both within and outside of the immediate influence of the

Geor~es Bank rnonitorin,~ program

69

discharge might be more appropriate. Alternatively. laboratory bioassay studies using representative discharge materials might be more informative than sporadic analyses of a limited number of field-collected organisms. Results from this study suggested that some aspects could be modified for future monitoring programs to improve the methodological sensitivity for detecting change. For example, the UV/fluorescence analysis of sediment and tissues was intended to provide semi-quantitative data for screening samples for the presence of petroleum hydrocarbons. The method is rapid and relatively inexpensive. However, monitoring temporal changes in TAE concentrations requires that the standards match the expected source of the hydrocarbons: for example, a particular crude oii or diesel fluid additive. Furthermore, the hydrocarbon composition of the drilling fluids varies depending on the additives present and downhole conditions encountered (Nell et al., 1985). A mixed aromatic standard was used for the analysis, resulting in a loss of specificity for drilling discharge materials. Thus, it was not possible to identify the source of aromatic hydrocarbons based on the UV/fluorescence spectra alone. Additionally, the pre-drilling study used FI D - G C to characterize sediment and tissue hydrocarbons, and comparisons between the pre-drilling study data and the majority of the UV/fluorescence results from this study are difficult because the two techniques do not yield comparable data. Additional GC and GC/MS analyses would have provided more definitive data for identifying hydrocarbon sources (
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ACKNOWLEDGEMENTS This program was conducted for the US Department of Interior. Minerals Management Service, under Contract Nos AA85 l -CT2-33 and 14-21-0001 30001. The authors would like to thank S. Barriault, J. Stone, and M. O'Byrne for word processing support: M. G u t t m a n for gas chromatography analyses: G. Smith t'or gas c h r o m a t o g r a p h y mass spectrometry analyses; G. H a m p s o n for assistance during the survey cruises: M. Bothner for providing sediment trace metal data: and an a n o n y m o u s reviewer for comments and suggestions on the original manuscript.

REFERENCES Abercrombie, F. N., Silvester, M. D. & Cruz, R. B. (1979). Simultaneous multielement analysis of biologically related samples with RF-ICP. In UItratrace metal analysis #1 hiological sciences and environment. (Risby, T. H. (Ed.)), American Chemical Society, Washington. DC, 10-26. Alpert, J. (Ed.)11978). North Atlantic Environmental Benchmark, Final Report. Energy Resources Co. Inc. Bureau of Land Management, New York OCS Office, Contract AA-550-CT6-51. Augenfeld, J. M., Anderson, J, W., Riley, R. G. & Thomas, B. L. (1982). The fate of polyaromatic hydrocarbons in an intertidal sediment exposure system: Bioavailability of Macoma inquhtata (Mollusca: Pelecypoda) and Abarenicola par(/ira (Annelida: Polychaeta). ,~[ar. Environ. Res. 7, 31-50. Ayers, R. C., Jr, Sauer, T. C., Jr, Stuebner, D. O. &Meck, R. P. (1980). An environmental study to assess the impact of drilling discharges in the mid-Atlantic. I. Quantity and fate of d ischa rges. I n: Symposium, Research on Environmental Fate and Eli?ors ~/ Drilling Fluids and Cutthtgs, Proceedings Vol. 1. American Petroleum Institute, Washington, DC, 382-418. Boehm, P. D. (1983). Coupling of particulate organic pollutants between the estuary and continental shelf and the sediments and water column in the New York Bight region. Canadian J. Fish. Aquatic Sci. 40 (Supplement 2). 262-76. Boehm, P. D. (1984). Aspects of the saturated hydrocarbon geochemistry of recent sediments in Georges Bank region. Organic Geochemistry, 7, 11-23. Boehm, P. D. & Farrington, J. W. (1984). Aspects of the polycyclic aromatic hydrocarbon geochemistry of recent sediments in the Georges Bank region. Environ. Sci. Tech., 18,840-5. Boehm. P. D. & Quinn, J. G. (1978). Bcnthic hydrocarbons of Rhode Island Sound. Esluar. and Coast. :~[ar. Sci. 6, 471-94. Boehm, P. D., Steinhauer, W. G., Fiest, D. L., Mosesman, N., Barak. J. E. & Perry. G. (1979). A chemical assessment of the present levels and sources of hydrocarbon pollutants in the Georges Bank Region. In: Proceedings of the 1979 Oil Spill Cm!/erence. American Petroleum Institute, Washington. DC, 333-41. Boesch. D. F., Butler. J. N.. Cacchionc, D. A., Geraci, J. R., Neff, J. M., Ray. J. P. & Teal, J. M. (1985). An assessment of the long-term environmental effects of U.S. offshore oil and gas development activities: Future research needs.

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Chapter I In: The long-term effects o/" offshore oil and gas development: An assessment and research strategy. (Boesch, D. F. & Rabelais, N. N. (Eds)). Final Report to National Oceanic and Atmospheric Administration. Rockville. M D Booth, P. N. & Presley. B. J. (1985). Distribution and behavior o/"drilling fluids and cuttings around Gulf of Mexico drilling sites. Final Report to American Petroleum Institute, Washington, DC, 105 pp. Bothner. M. H., Rendigs, R. R., Campbell, E.. Doughten, M., Aruscavage, P. J.. Dorrzapf, A., Johnson, R.. Parmenter, C. M.. Pickering, M., Brewster, D. & Brown, F. (1982}. The Georges Bank ,~[onitoring Program: .4nalvsis of trclce metals in bottom sediments during the first years o/'monitoriny,, lffinal Report submitted to the Minerals Management Services, Washington. DC, 66 pp. Bothner, M. H.. Rendigs, R. R., Campbell, E., Doughten, M. W., Parmenter, C. M., Pickering, M. J., Johnson, R. G. & Gillison, J. R. (1984). The Georges Bank Monitoring Program. atzalvsis of trace metals in hottom sediments during the second year q/ monitoring. Final Report submitted to Mineral Management Service, Washington. DC. 85 pp. Bothner, M. H.. Rendigs, R. R.. Campbell. E., Doughten, M. W., Parmenter, C. M., O'Dell. C. H., DiLiso. G. P.. Johnson. R. G.. Gillison. J. R. & Rait. N. (1985). The Georges Bank Monitoring Program: Analysis of trace metals in bottom .sediment.~ durin~ the third year q/monitoring. Final Report submitted to Minerals Management Service, Washington, DC, 98 pp. Bothner, M. H., Spiker, E. C.. Johnson, P. P., Rendigs, R. R. & Aruscavage, P. J. (I 981). Geochemical evidence ['or modern sediment accumulation on the continental shetfoffsouthern New England. J. o/Scd. Petrology. 51,281-92. Brown, D. W.. Ramos, L. S., Uyeda, M. Y., Friedman, A. J. & MacLeod, W. D. Jr. (,1980). Ambient temperature extraction of hydrocarbons from marine sediment--Comparison with boiling-solvent extractions. In: Petroleum in the mariJle em'iremntcnt (Petrakis, L. & Weiss, F. T. IEds)), American Chemical Society, Washington, DC. Butman. B. & Folger, D. W. (1979). An instrument system for long-term sediment transport studies on the Continental Shelf. J. Geophys. Res. 84, 1215- 20. Butman, B. & Moody, J. A. (1983). Observations of bottom currents and sediment movement along the U.S. East Coast Continental Shelf during winter. In: Environmental Geologic Studies of the United States East Coast Mid and North .4thmtic outer Continental Shelf Area. 1980-1982, Vol. Ill. McGregor. B. A. (Ed.)), North Atlantic Region. US Geological Survey Final Report to Minerals Management Service, Washington, DC, 84 pp. Butman. B., Beardsley, R. C., Magnell. B.. Frye. D., Vermersch, J. A.. Schlitz, R., Limeburner, R.. Wright, W. R. & Noble. M. A. (1982). Recent observations of the mean circulation on Georges Bank. J. q/Phys. Ocean. 12. 569-91. Capuzzo, J. M. (1985). Biological effects of petroleum hydrocarbons: Assessments from experimental rest.tits. Chapter 8. In: The long-term ~[/'ects q/'qff#lore oil and,¢as dcvelopment. An assessnlent and a research strategy. (Boesch. D. F. & Rabelais, N. (Eds)), Final Report to National Oceanic and Atmospheric Administration, Rockville, M D. Davies, J. M.. Addy. J. M., Blackman. R. A., Blanchards, J. R., Ferbrache, J, E., Moore. D. C., Somerville, H. J., Whitehead, A. & Wilkerson, T. (1984), Environmental effects of the use of oil-based drilling muds in the North Sea. Mar. Poll. Bull. 15, 363-70.

72

Charles R. Phillip~ et al.

Delaune, R. D., Hambrick, G. A. & Patrick, W. H. Jr. i1980). Degradation of hydrocarbons in oxidized and reduced sediments. Mar. Poll. Bull. 11, 103-6. Farrington. J. W. & Meyers, P. A. (1975). Hydrocarbons in the marine environment. In: Environmental chemistry, Vol. 1. (Eglington. G. S. (Ed.)), 109-36, Burlington House, London. Farrington, J. W. & Tripp, B. W. (1977). Hydrocarbons in Western North Atlantic surface sediments. Geochim. Cosmochim. Acta 41, 1647-5t. Farrington. J. W.. Frew, N. M., Gschwend, P. M. & Tripp. B. W. (1977). Hydrocarbons in cores of Northwest coastal and continental margin sediments. Estuar. and Coast. Mar. Sci. 5, 793-803. Farrington, J. W., Wakeham, S. G., Livramento, J. B., Tripp. B. W. & Teal, J. M. (1986). Aromatic hydrocarbons in New York Bight polychaetes: Ultraviolet fluorescence analyses and gas chromatography/gas chromatography-mass spectrometry analyses. Environ. Sci. Tech. 20, 69-72. Grahl-Nielsen, O., Sundby, S., Westrheim, K. & Wilhelmsen. S. (1980). Petroleum hydrocarbons in sediment resulting from drilling discharges from a production platform in the North Sea. In: Symposium, research on environmental fate and effects of drilling fluid9 and cuttings, Proceedings. Vol. L American Petroleum Institute, Washington, DC, 541-61. Hauser. T. R. & Pattison, J. N. (1972). Analysis of aliphatic fraction of air particulate matter. Environ. Sci. Tech., 6, 549-55. Hoffman, E. J. & Quinn, J. G. (1979). Gas chromatographic analyses of ARGO M E R C H A N T oil and sediment hydrocarbons at the wreck site. Mar. Poll. Bull. 10, 20-24. Hoffman, E. J., Quinn, J. G., Jadcmer, R. & Fortier, S. H. ([979). Comparison of UV fluorescence and gas chromatographic analyses of hydrocarbons in sediments from the vicinity of the Argo Merchant wreck site. Bull. Environ. Contam. Toxicol. 23, 536-43. Houghten, J. P., Britch, R. P., Miller, R. C., Runchal, A. K. & Falls, C. P. (1980). Drilling fluid dispersion studies of the Lower Cook Inlet, Alaska. C.O.S.T. well. In: Symposium, research on en vironmental fate and ~[]'ects of drilling fluids and cuttings, Proceedings: Vol. I. American Petroleum Institute, Washington, DC, 285-308. Kovats, E. (1958). Gas chromatographische Charaketerisierung organischer Verbindungen. Tell I: Retentions indices Aliphatischer, Halogenide. Alkohole, Aldehyde, and Ketone. Helv. Ch#n. Acta, 41, 1915-32. Laflamme, R. E. &Hites, R. A. (1978). The global distribution of polycyctic aromatic hydrocarbons in recent sediments. Geochim. Cosmochon. Acta, 42, 289304. Maciolek-Blake, N., Grassle, J. F., Blake, J. A. & Neff, J. M. (1984). Georges Bank Benthic lnfauna Monitoring Program: Final Report Jbr the Second Year of Sampling. Prepared for the US Department of Interior, Minerals Management Service, Washington, DC, 173 pp. Mariani, G. M., Sak, L. V. & Johnson. C. C. (1980). An environmental monitoring study to assess the impact of drilling discharges in the mid-Atlantic [If. Chemical and physical alterations in the benthic environment. In: Symposium, research on environmental role and effects of drilling fluids and cutt#lgs, Proceedings, Vol. I. American Petroleum Institute Washington, DC, 438-98. Martin, J. H. & Knauer, G. A. (1973). The elemental composition of plankton. Geochim. Cosmochim. Acta, 37, 1639-53,

Geor~es Bank monitoring, pro~,ranl

73

National Research Council. (1980). The International Mussel Watch, National Academy of Sciences. Washington. DC. 247 pp. National Research Council. (1983). Drillings discharges in the marine environment. Panel on Assessment of Fates and Effects of Drilling Fluids and Cuttings in the Marine Environment. National Academy Press, Washington. DC, 180 pp. Neff. J. M. (1985). Biological effects of drilling fluids, drill cuttings, and produced waters. Chapter 10. In: The long-term e~'ects o/ofl'~hore oil and gas development: An assessment and a research strategy. (Boesch, D. F. & Rabelais, N. N. (Eds)). Final Report to National Oceanic and Atmospheric Administration. Rockville, MD. Neff. J. M. & Anderson, J. W. ( [ 981 ). Response q/marine animals to petroleum and spee(B'c petroleum hvdrocarhons. Halstead Press, New York. 167 pp. Neff, J. M., Rabelais, N. N. & Boesch, D. F. (1985). Offshore oil and gas development activities potentially causing long-term environmental effects. Chapter 4. In: The long-term effects q/'offsh~re oil and gas development: An assessment anda research strate g)'. (Boesch. D. F. & Rabelais, N. N. (Eds)), Final Report to National Oceanic and Atmospheric Administration, Rockville, MD. Neff', J. M., Cox, B. A., Dixit, D. & Anderson, J. W. (1976). Accumulation and release of petroleum-derived aromatic hydrocarbons by four species or" marine animals. Mar. Biol., 38, 279 89. Pancirov, R. J. & Bro~vn. R. A. (1977). Polynuclear aromatic hydrocarbons in marine tissues. Envircm. Sci. rech. ! 1,989-92. Payne. J. R., Nemmers, J. E., Jordan. R. E., Mankiewicz, P. J., Oesterle. A. D.. Eaughon, S. S. & Smith, G. (1980). Measurement (!/ Petroleum Hydrocarbon Burdens in Marine Sediments h)" Three Commonly Accepted Procedures: Results of a NOA A hzter-Lahoratorv Calihrati(m Exercise; Jan. 1979. OCSEAP, National Oceanic and Atmospheric Administration, Environmental Research Laboratory, Boulder. CO. 34 pp. plus appendix. Paync, J. R., Eambach, J. L., Jordan, R. E., McNabb, G. D., Jr, Sims. R. R., Abasumara, A., Sutton. J. G., Generro, D., Ganger, S. & Shokes, R. F. (1982). Georges Bank Monitoring Program: Analysis of hydrocarbons in bottom sediments and analt'sis q/" hv~bocarbons and trace metals in benthic /immt. Final Report prepared for US Department of the Interior. Minerals Management Service, Washington, DC, 189 pp. Payne. J. R., Lambach, J. L., Jordan, R. E., Phillips, C. R., McNabb, G. D., Jr, Bechcl, M. K., Farmer, G. H., Sims, R. R., Jr. Sutton, J. G. & Abasuma, A. (1983). Georges Bank Monitoring Program: .4nalvsis of hydrocarons in bottom sediments and analysis (~/'hydrocarhon and trace metals in henthic Jauna during t/re second year of monitoring. Final Report prepared for the US Department oi" the Interior, Minerals Management Service, Washington, DC, 151 pp. Payne. J. R., Lambach, J. L., Farmer. G. H., Phillips, C. R., Beckel, M. K.. Sutton. J. G. & Sims, R. R., Jr. (1985a). Georges Ba~tk Monitoring Program: .qnalvsis ~/ hy~hocarhons in bottom sediments atut analysis q/ hy~h'ocarhons and trace metals itt henthic fautta ~htring the third year (;/m~mitoritrg. Final Report prepared t\-~r US Department of the Interior, Minerals Management Service. Washington, DC, 106 pp. Payne. J. R., Clayton, J. R., Phillips, C. R., Lambach, J. L. & Farmer. G. H. (1985h). Marine oil pollution index. Oil and Petrochemical Pollution, 2, 173-91,

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Charles R. Phillips et al.

Prahl. F. G. & Carpenter. R. (1983). Potycyclic aromatic hydrocarbon (PAH)phase associations in Washington coastal sediment. Geochim. Cosmochim. Acta, 47, 1013-23. Thompson. S. & Eglington. G.S. 1978). The fractionation of a recent sediment for organic geochemical analysis. Geochim. Cosrnochim. Acta, 42, 199-207. Tripp. B. W., Farrington, J. W. & Teal, J. M. ( 1981 ). Unburned coal as a source of hydrocarbons in surface sediments. Mar. Poll. Bull. 12. 122-6. Twichell, D. C.. McClennen, C. E. &Butman, B. (1981). Morphology and processes associated with the accumulation of the fine-grained sediment deposit on the southern New England Shelf. J. Sed. Petroh),gy, 51,269-80. Van Vleet. E. S. & Quinn. J. G. (1977). Input and fate of petroleum hydrocarbons entering the Providence River and Upper Narragansett Bay from ~vastewater effluents. Environ. Sci. Tech. 2, [086-9 I. Wakeham, S. G. (1977). Synchronous fluorescence spectroscopy and its application to indigenous and petroleum-derived hydrocarbons in lacustrine sediments. Environ. Sci. Tech. 21,272-6.