Gulf of Mexico dissolved hydrocarbons associated with the Ixtoc I mousse

Marine Pollution Bulletin

population dynamics of metal uptake in the three gastropods examined here because no data are available from an unpolluted site. However, it is of great interest to note that positive skewness occurred very frequently in the frequency distributions. Since no known environmental or ecophysiological factor was found to cause this, it would be of interest to know whether skewness might arise from factors of an inherited nature, i.e. a pattern of genetic diversity. Furthermore, it would be of interest to know whether skewness of this sort is peculiar to molluscs or occurs in other phyla as well. I thank Professors J. Shaw, B. L. Bayne and R. B. Clark for academic guidance and P. Garwood for drawing the illustrations. Much help was also received from A. Lobel and the staff of the Dove Marine Laboratory. Contribution No. 1247 from the Center for Environmental and Estuarine Studies of the University of Maryland.

Boyden, C. R. (1974). Trace element content and body size in molluscs. Nature, Lond., 251, 311-314. Boyden, C. R. (1977). Effect of size upon metal content of shellfish. J. mar. BioL Ass. UK, 57,675-714. Coombs, T. L. (1977). Uptake and storage mechanisms of heavy metals in marine organisms. Proc. Analyt. Div. Chem. Soc. 14,218-221.

George, S. G. & Coombs, T. L. (1977a). Effects of high stability ironcomplexes on the kinetics of iron accumulation and excretion in Mytilus edulis. J. exp. mar. Biol. Ecol., 28, 133-140. George, S. G. & Coombs, T. L. (1977b). Effects of chelating agents on the uptake and accumulation of cadmium by Mytilus edulis. Mar. Biol., 39, 261-268. Lobel, P. B. (1981a). Zinc in mussels from an iron pipe. Mar. Pollut. Bull., 12,410-411. Lobel, P. B. (1981b). Bioaccumulation of zinc in Mytilus edulis. Ph.D. thesis. University of Newcastle-upon-Tyne, Newcastle-upon-Tyne, England. Lobel, P. B. & Wright, D. A. (in press). Total body zinc concentration and allometric growth ratios in Mytilus edulis collected from different shore levels. Mar. Biol. Phillips, D. J. (1980). Quantitative Aquatic Biological Indicators. Applied Science Publishers, Barking, Essex. Priest, S. (1975). A study of heavy metal contamination in two intertidal invertebrates. M.Sc. thesis. University of Durham, Durham. Purchon, R. D. (1968). The Biology of the Mollusca. Pergamon Press. Oxford. Shimizu, M. & Tsuji, S. (1980). Heavy metal content of the common mussel, Mytilus edulis, and its variation. In Management of Environment (B. Patel, ed.). Wiley Eastern, New Delhi. Sokal, R. R. & Rohlf, F. J. (1969). Biometry. W. H. Freeman, San Francisco. Watling, H. R. &Watling, R. J. (1976). Trace metals in Choromytilus meridionalis. Mar. Pollut. Bull., 7, 91-94. Wright, D. A. (1978). Heavy metal accumulation by aquatic invertebrates. In Applied Biology (T. H. Coak, ed.), Vol. 3, pp. 331-394. Academic Press, London.

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MarinePollutionBulletin. Vol. 13, No. 5, pp. 174-177.1982. Printed in Great Britain.

Gulf of Mexico Dissolved Hydrocarbons Associated with the IXTOC I Mousse S. A. MACKO,* J. K. WINTERS and P. L. P A R K E R t The University o f Texas, Marine Science Institute, Port Aransas Marine Laboratory, Port Aransas, T X 78373, USA *Present address: Carnegie Institution of Washington, Geophysical Laboratoo,. Washing,ton. DC 20008, USA

Increased levels of dissolved hydrocarbons were observed in the western Gulf of Mexico during the late summer of 1979. This period was associated with heightened levels of surface tar and oil/water emulsion (mousse) directly resulting from the blowout of the Ixtoc I oil well in the Bay of Campeche on 3 June 1979. The observed concentrations of total dissolved hydrocarbons (up to 656.9 ng I-t, n-alkanes) were one to two orders of magnitude above levels observed at control stations (5.2 ng I-t, n-alkanes) and stations in the same area during the earlier Bureau of Land Management (BLM) baseline study. The highest concentrations observed were approximately of the same level as those obtained in an artificial spill/weathering experiment.

A direct result of an oil spill in the marine environment is the dissolution of a portion of that oil into marine waters. This soluble fraction has been shown to be toxic to marine plants (Winters et al., 1976; Winters et al., 1977) and animals (Nicol et al., 1977; Lee & Nicol, 1978). The exact nature of the 'dissolved' material is often hard to define in the natural setting. Because of low solubility, the n-alkane fraction is t T o whom requests for reprints should be addressed.

174

usually in negligible concentrations in laboratory studies involving oil accommodated seawater (OAS) (Lee et al., 1980). In an oceanic environment, however, because of higher energy of mixing or the presence of other types of organic matter, formation of solubilized micelles of oil (Lee et al., 1974) or of colloidal mixtures with organic molecules (Boehm & Quinn, 1974; McAuliffe, 1976) can increase levels of compounds in the' dissolved' state. The dissolved fraction of hydrocarbons in seawater has been associated with phytoplankton sources (Barbier el al., 1973) or a combination of sources including terrestrial plant matter and anthropogenic activities (Kennicutt & Jeffrey, in press). The western Gulf of Mexico was surveyed in the BLM program to establish a baseline of dissolved hydrocarbons (Parker et al., 1979a), in order to estimate possible future impacts. In June 1979, the Ixtoc I oil well in the Bay of Campeche in the southern Gulf of Mexico, blew out. The well continued to spew oil for almost eight months, eventually releasing an estimated 4.5 × 1@ tonnes (approximately 3.2 × 106 barrels). Roughly two months after the blowout, water/oil emulsion (mousse) from this well was observed entering coastal waters of Texas.

Volume 13/Number 5/May 1982 Reference

We report here on elevated levels of dissolved hydrocarbons in the northwest Gulf of Mexico associated with the presence of the Ixtoc I mousse during the summer of 1979. The toxicity of oil accommodated seawater from the oil slick has been reported to be low for certain marine invertebrates (Lee et al., 1980). However, water-soluble components' toxicities and long-term effects will vary with the organism being exposed and length of exposure. The scope and long-term effect of the OAS from this spill have yet to be determined.

n-C~H~s I

I

4-1

!8N • C-IO

*n'-I

rr-2

d-2

A Ti'-6 iT[- 7

!7N m 4/I •I 7-1 .15-1

8

5Z-I

26 N

Browneville mP-I

BLM : PT-I Fell t977 Retention time

Fig. 2 Representative hexane eluate gas chromatograms from this study compared to a station from the same area during the earlier BLM study (Parker etal., 1979a).

AV-6 25N

I

I~/

• Cruise 2 • Cruise I 24 N

98 W

97W

96W

accomplished with a 27 m OV-101 glass capillary column. Programmed conditions for the separation were: initial temperature (100°C) for 3 min., 2°C per minute rate, final temperature of 255°C for 20 min. and post temperature o f 265°C for20 min.

95W

IXTOC - I Dissolved hydrocorbons Fig. 1 Location of stations in the study.

Methods Samples were collected 3-10 m below the sea surface during two cruises of the R.V. Longhorn into the region of the Gulf where the mousse had been observed (4-8 August 1979 and 15-22 August 1979; Fig. 1). The collection device consisted of a solvent-washed glass carboy which could be opened and closed from the ship's deck. The samples were filtered through glass fibre filters (GFC, Whatman) which had been previously extracted with redistilled chloroform. The filtrate was then poisoned with chloroform and returned to the laboratory. Samples were extracted with redistilled chloroform in a continuous flow extractor, and extracts were concentrated in a reduced pressure Kuderna-danish apparatus (Winters et al., in prep.). Samples were then separated by elution with hexane followed by benzene on a mixed bed (alumina: silica gel, 1 : 2 by volume) column. Gas Chromatographic analysis was performed on a Perkin-Elmer 910 gas chromatograph equipped with a flame ionization detector. Separation was

Results In the field, the oil was observed to be surface sheen, tarballs, or thick patches of chocolate-brown emulsion (mousse). No samples of dissolved hydrocarbons were taken through the mousse itself in order to prevent loss of sampling equipment due to contamination. The variability of surficial material was reflected in the dissolved hydrocarbon concentrations. Certain stations (4-1, 5-1 and II-2) contained concentrations of total dissolved hydrocarbons (seen as n-alkanes) 1 to 2 orders of magnitude above levels observed at other stations (C-10, 1-1, for example) or for other stations in the same area during the earlier BLM study. Of particular interest was the fact that a small odd over even preference was observed in the hexane (n-alkane) fraction of those samples with the elevated concentrations (Fig. 2, Table 1). The benzene eluates were quite variable in composition (Fig. 3) and did not appear to resemble the aromatic fraction of the water-soluble material from the laboratory study of the original oil (Parker et al., 1979b). Total concentrations of hydrocarbons were observed to be higher in stations further north during the second cruise. This can be attributed to the continuing progress of the mousse northward along the Texas coast during the time between cruises (Fig. 4). Concentrations were observed to be 175

Marine Pollution Bulletin TABLE 1 • 4-1

Concentrations of dissolved n-alkanes (ng 1- i). Relative retention

Station

6oo -

index

C-IO

4-1

5-1

11-2

11-6

1500 1600 1700 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 2900 3000 3100

0.1 0.9 0.2 0.6 0.1 0.2 0.2 0.2 0.3 0.3 1.2 0.3 0.4 0.3 0.2 0.1 0.2

1.8 2.4 10.6 25.8 46.7 39.2 53.0 47.2 70.9 51.0 79.2 51.7 82.6 35.5 54.4 9.1 9.1

16.5 14.6 24.0 33.8 36.2 23.4 21.0 16.1 18.9 12.9 26.2 13.9 17.3 12.9 22.3 10.2 8.2

15.0 10.1 23.9 6.8 7.2 10.9 7.2 7.2 10.2 14.1 51.2 26.8 21.9 32.7 32.3 26.4 29,1

4.0 4.3 4,1 4.7 4.9 4.8 5.0 4.6 4.0 5.7 6.0 5.1 6.9 5.1 6.2 7.3 6.0

Total n-alkanes

5.2

656.9

328.5

349,4

86,2

Average conc.

0.3

36.8

19.3

19.4

5.1

\

IXTOC-I D~ssolved hydrocarbons

\ \ 400-

\

-

aS-I I I I I

.., o

~

200

I •U-i

• 11-2 °" %, o" ,°

*° "%

° e*

°*'..%

IV-I! "~1,,-. '" "~" 7-1 I ~-~ "~¢-#-r -1-20 40 Distonce from shore,

0

%

,'

1 60

11-6 A.. 11-7"J .~V-6 80

km

Fig. 4 Concentration of dissolved hydrocarbons with distance from shore.

slightly greater at 3 m below the surface than at a depth of 10 m.

Discussion

1"i"-2

Near surface concentrations of dissolved n-alkanes observed during the Ixtoc I spill for the three stations 4-1,5-1 and II-2 were of similar magnitude as those observed in an artificial spill and weathering experiment in a large outdoor tank (Winters, 1978). This might indicate that the dispersal in a large reservoir such as the Gulf does not readily occur in the immediate area of an oil slick. It appears that large volumes of oil-contaminated seawater are able to remain in patches which are chemically distinct from surrounding waters. The odd-even preference of the higher n-alkanes is similar to the data of Winters (1978). Two estimates for this phenomenon are that there exist either physical differences in dissolution in saline waters or biological actions requiring either preferential utilization of even carbon chains or

]E-7 TABLE 2 Concentrations of dissolved n-alkanes (ng I I} from (1) an artificial spill (Winters, 1978), and (2) BLM Station, BOVH, Fall, 1977.

BLM :

I~-I

FOIl i977

Refention time

Fig. 3 Representative benzene eluate gas chromatograms from this study compared to a station from the same area during the earlier BLM study (Parker etal., 1979a).

176

Relative retention index

Artificial spill m

dissolved ~2)

1700 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800 2900 3000

17.0 19.0 40.0 30.0 35.0 22.(/ 32.0 23.0 19.0 16.0 16.0 7.0 t 1.0 3.0

6.4 2.9 5.1 3.8 6.8 4.6 5.3 4.8 4.5 3.9 5,3 4,2 5.1 3.9

290.0

71.3

20.7

4.8

Total n-alkanes Average concentration

BLM

Volume 13/Number 5 / M a y 1982

production of high levels of odd carbon chains in the area of the spill. The variability of the aromatic fraction of the dissolved hydrocarbons could also be explained by differential degradative processes resulting in substituted aromatic materials unlike the original oil. The same type patchiness of the n-alkane fraction was observed in the aromatic fraction. One other possible explanation for such a variable distribution of aromatic materials is changes in the chemical composition of the oil from the well during the period of the spill (eight months). To our knowledge, no samples along this line of research were taken at the well-site. Although visible evidence of oil pollution as well as elevated levels of hydrocarbons were noted at several stations, chemical data including odd-even preference and patchiness of both n-alkane and aromatic compounds indicate conditions not generally associated with petroleum pollution.

We are grateful to the Captain and crew of the R.V. Longhorn and especially Mr R. Anderson and Dr M. Northam for the collection of these samples. We thank Dr M. Estep for comments on the manuscript. Funds for this research were provided by the US Department of Commerce: NOAA contract No. NA 79AC00141. Contribution No. 516 from Port Aransas Marine Laboratory, The University of Texas.

Barbier, M., Joly, D., Saliot, A. & Tourres, D. (1973). Hydrocarbons from seawater. Deep-Sea Res., 20, 305-314.

MarinePollutionBulletin,Vol. 13. No. 5. pp. 177-178,1982. Printed in Great Britain.

Health of the Baltic Sir, Referring to the book review of J. S. Gray (Mar. Pollut. Bull., 13, 34-35, 1982) entitled 'Health of the Baltic', I would like to thank you and your Bulletin for publishing that extensive review of the assessment document published by the Baltic Marine Environment Protection Commission, Helsinki Commission. In the article there is one particular point which might need additional information. The aims of the Convention on the Protection of the Marine Environment of the Baltic Sea Area are given in a very limited way. It is true that the prevention of marine pollution from ships and the combating of pollution are very important elements of the Helsinki Convention. Also one of the Annexes follows closely the principles given in MARPOL 73/78 for tile special areas. However, even in the maritime field there are several additional activities, e.g. the Baltic Position Reporting System (BAREP) and a reporting system for early warning for pollution incidents. The BAREP programme was initiated for a trial period of two years on 1 July 1981. According to it, loaded oil tankers of 20 000 GRT and above, loaded gas carriers of

Boehm, P. D. °7o Quinn, J. G. (1974). The solubility behavior of No. 2 fuel oil in sea water. Mar. Pollut. Bull., 5, 101-105. Kennicutt, M. C. & Jeffrey, L. M. (in press). Chemical and G C - M S characterization of marine dissolved lipids. Mar. Chem. Lee, C. C., Craig, W. K. & Smith, P. J. (1974). Water-soluble hydrocarbons from crude oil. Bull. Envir. Contam. Toxic., 12,212-217. Lee, W. Y., Morris, A. & Boatwright, D. (1980). Mexican oil spill: a toxicity study of oil accommodated in seawater on marine invertebrates, Mar. Pollut. Bull., 11, 231-234. Lee, W. Y. & Nicol, J. A.C. (1978). Individual and combined toxicity of some petroleum aromatics to the marine amphipod Elasmopus pectenierus. Mar. BioL, 48, 215-222. McAuliffe, C. D. (1976). Surveillance of the marine environment for hydrocarbons. Mar. Sci. Commun., 2, 13-42. Nicol, J. A. C., Donahue, W. H., Wang, R. T. & Winters, K. (1977). Chemical composition and effects of water extracts of petroleum on eggs of the sand dollar Mefita quinquiesperforata. Mar. Biol., 40, 309-316. Parker, P. L., Scalan, R. S. & Winters, J. K. (1979a). High molecular weight hydrocarbons in zooplankton, sediment and water. Environmental Studies, STOCS, Biology and Chemistry. BLM. Washington, D.C. Parker, P. L., Scalan, R. S., Winters, J. K., Boatwright, D. C. & Scalan, D. L. (1979b). Chemical characterization of lxtoc 1 samples and oil-seawater mixtures used for toxicity studies. Unpublished report. Winters, J. K. (1978). Fate of petroleum derived aromatic compounds in seawater held in outdoor tanks. Supplemental studies, environmental studies, STOCS, Biology and Chemistry, BLM, Washington, D.C. Winters, J. K., O'Donnell, R., Batterton, J. C. & Van Baalen, C. (1976). Water-soluble components of four fuel oils: Chemical characterization and effects on growth of microalgae. Mar. Biol. 36,269-276. Winters, K., Van Baalen, C. & Nicol, J. A. C. (1977). Water soluble extractives from petroleum oils: Chemical characterization and effects on microalgae and marine animals. Rapp. P.v. Rbun. Cons. perm, int. Explor. Mer, 171,166-174. Winters, K., Macko, S. A. & Parker, P. L. (in prep.). Isolation of the dissolved hydrocarbon fraction from marine waters.

0025-326X/82/050177-02$03.00/0 PergamonPressI Id.

1600 GRT and above and loaded chemical tankers of 1600 GRT and above carrying noxious liquid substances are requested to participate in the system by transmitting the prescribed reports to the national position reporting centres of the Contracting Parties when being inbound or outbound from the Convention Area or when navigating in the area. The Early Warning Reporting System for Pollution Incidents was also established 1 July 1981 in order to introduce a uniform reporting procedure between the Contracting Parties in relation to imminent pollution threats and for the exchange of detailed information on pollution incidents including calls for assistance from the other Contracting Parties. However, prevention and combating the ship-generated pollution form only one part of the activities in the framework of the Convention on the Protection of the Marine Environment of the Baltic Sea Area, the Helsinki Convention. The other substantive topics are the counteractions against land-based pollution, including airborne harmful substances, a general prohibition of dumping with the exclusion of dredged spoils and an agreement to limit pollution from exploration and exploitation of sea-bed resources. Thus, the Helsinki Convention, when signed in 1974, became the first regional Convention to embrace 177