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Edited by Leon P. Zann
Great Barrier Reef Marine Park Authority, Townsville Queensland
Ocean Rescue 2000 Program
Department of the Environment, Sport and Territories, Canberra, 1995
ISBN 0 642 17406 7
D W Connell Ph.D. D.Sc.
Faculty of Environmental Sciences
Griffith University and
Government Chemical Laboratory
Both crude and refined petroleum usually consist of hundreds of chemical substances. Common petroleum products together with their basic characteristics are shown in Table 1. Chemically the components of crude petroleum can be divided into two classes: alkanes and aromatic hydrocarbons. The aromatic hydrocarbons include the environmentally suspect polycyclic aromatic hydrocarbons (PAHs) which occur in relatively low concentrations in most petroleum substances. Refined petroleum products can contain the alkenes which are prepared synthetically and are somewhat similar to the alkanes in environmental properties.
All of these products are transported in Australia or manufactured in Australian petrochemical plants. In addition crude petroleum is shipped into Australia and around the Australian coast. Marine oil fields operate in Bass Strait and on the North West shelf at present with others being developed in other marine areas. Most of these activities have generated discharges during production processes as well as accidental spills. Petroleum substances also occur in relatively low concentrations in sewage (Connell 1974) and urban run-off , but the total amount discharged is relatively high due to the large volumes involved.
Properties which influence the behaviour of petroleum compounds in the environment are listed in Tables 1 and 2. The natural gases and petrol have relatively low boiling points and evaporate readily from the surface of water. As a general rule they evaporate within 24 hours. The other petroleum products exhibit increasing persistence in the environment with increasing number of carbon atoms and boiling point. At the extreme end of the range the asphalts and residual oils exhibit long-term persistence, usually over several decades.
Table 1: Characteristics of some petroleum products
|Petroleum Product||Hydrocarbon Types Present||Boiling Point Range (ºC)||Number of Carbon Atoms|
|Petrol||Alkanes and Aromatics||20-200||4-12|
|Kerosene, Jet fuel and Diesel||Alkanes and Aromatics||185-345||10-20|
|Asphalt and Residual oils||Complex Aromatic||>540||>40|
Table 2: Physicochemical and biological properties of some typical petroleum hydrocarbons1
|Compound||Aqueous Solubility (mg/L)||Octanol-Water Partition Coefficient (log KOW)||Toxicity (mg/L)||Persistences (half-life in days)|
|n-hexane||9.5||813 (2.91)||> 100 (fish)2||ca 4 (mussels)|
|n-decane||0.004||3.8x105 (5.58)||> 10 (mussel larvae)3||ca 4 (mussels)|
|n-tetradecane||2.82x10-4||1.6x107 (7.20)||Not known||ca 4 (mussels)|
|benzene4||1780||135 (2.13)||5.8-46 (several fish species)2||Not known|
|naphthalene4||32||2290 (3.36)||1.24-150 (fish)2||1.5 (mussels)|
|benzo(a)pyrene4||0.0037||1.1x106 (6.04)||> 1 (marine worms)2||16 (mussels)|
Figure 1 distribution patterns of a chemical in different phases in the environment. The equilibrium constants (K values) are shown between phases and concentrations in a phase at equilibrium (C values) indicated.
Some physicochemical and biological properties of typical representatives of the alkane and aromatic hydrocarbon groups are shown in Table 2. All members exhibit relatively low solubility in water with benzene (a common petrol component) being the most soluble at 1780 mg/L. The octanol/water partition coefficient (KOW) is an important property reflecting the lipid solubility of a substance. The most biologically active substances, in terms of toxicity and bio-accumulation, have log KOW values between 2 and 6, and are referred to as lipophilic compounds. Many hydrocarbons fall into this group as illustrated by the data in Table 2.
As a group the alkanes have very low toxicity which is reflected by the low toxicity of n-hexane and n-decane recorded in Table 2. On the other hand the aromatic compounds (benzene, naphthalene and benzo(a)pyrene) are described as 'relatively toxic' to aquatic organisms. Persistence in biota is low for the n-alkanes but higher for the aromatic hydrocarbons, particularly the PAHs (e.g. benzo(a)pyrene, Table 2). It is important to note that many of the aromatic hydrocarbons, particularly the PAHs, are carcinogens which have been implicated in many a wide range of human health problems and also disease problems with aquatic organisms (Grimmer 1983).
Another important environmental property of the PAHs is that they have strong bio-concentration capacities in aquatic organisms. For example naphthalene, the simplest PAH, has a bio-concentration factor (concentration in fish:concentration in water) of 426, while for benzo(a)anthracene it is 10 000 and for pyrene, 2690 (Connell 1990; Connell & Schüürmann 1988). Also, the PAHs and other hydrocarbons have strong affinities with bottom sediments, dependent on the amount of organic matter present. Gravels and coarse sands have little capacity to take up hydrocarbons whereas silts and muds with a high organic matter content have a strong capacity to take up lipophilic hydrocarbons. This is reflected in the high KOC values (concentration in organic carbon containing matter in sediment:concentration in water) which range up to about 106.
In the discussion above the environmental properties of petroleum are discussed in terms of the individual substances. Petroleum products occur as complex mixtures of individual substances. The environmental properties of petroleum products can be inferred from the properties of the individual substances but these may be modified to some extent by the presence of other substances.
The marine environment can be considered to consist of several phases, as illustrated in Figure 1, and when a lipophilic chemical is discharged to the marine environment it distributes into these phases. In general terms the sediments and biota have a relatively strong affinity for lipophilic hydrocarbons, and concentrations in these phases would be expected to be relatively high. On the other hand concentrations in water would be expected to be low, due principally to the very low water solubility of lipophilic hydrocarbons (Kayal & Connell 1990; Connell & Hawker 1986).
An outline of the concentrations of petroleum hydrocarbons reported in Australian waters and sediments is shown in Table 3. It is noteworthy that, as expected, the concentrations in water are very low compared with those in sediments. As a general rule less than about 1 mg L-1 total hydrocarbons in water, as are observed in the Great Barrier Reef (GBR), represent background levels . Port Phillip and Westernport Bays exhibit background levels but with some zones of contamination. PAHs are natural components of the environment and occur in trace concentrations in rivers. The concentrations in rivers reported in Table 3 represent levels which occur in these waters due to urban and sewage discharges and also there are sometimes petrochemical industry activities in the vicinity. Similar general observations to those on waters can be made regarding the sediments. However Rowley Shelf in the north-west of WA exhibits a low level of petroleum contamination in a region where urban and sewage discharges are very low: such contamination as occurs is believed to be associated with the various activities associated with the extraction of petrochemicals in the area.
Table 3: Occurrence of petroleum hydrocarbons in Australian waters and sediments
|Location||Concentration [µg/L] and (Hydrocarbon Type)||Reference|
|Brisbane River||0.10-0.13 (PAHs)
|Kayal and Connell (1989)
Smith et al. (1991)
|Western Port||<0.1-7.1 (petroleum)||Burns and Smith (1980)|
|Parramatta River||0.17-0.41 (PAHs)||Smith et al. (1991)|
|Port Phillip Bay||0.2-22.6 (petroleum)
0.25-0.70 (total hydrocarbons)
|Burns and Smith (1981)
Murray et al. (1988)
|Yarra River||0.05-0.41 (PAHs)||Smith et al. (1991)|
|Great Barrier Reef||0.29 (petroleum)||Coates et al. (1986)|
|Location||Concentration [mg/kg, unless noted] and (Hydrocarbon Type)|
|Brisbane River||3.9-16.1 (dry wt.) (PAHs)||Kayal (1991); Kayal and Connell (1989)|
|Western Port||2.3-5,271 (dry wt.) (total hydrocarbons)||Burns and Smith (1977)|
|Parramatta River||0.1-13.6% (grease)||Furzer (1975)|
|Yarra River estuary||0.12-10.9 (PAHs)
|Bagg et al. (1981)
Maher et al. (1979)
|Yarra River/Hudson's Bay - Port Phillip Bay||43-955 (petroleum hydrocarbons)||Burns and Smith (1982)|
|6-1516 (petroleum hydrocarbons)
|Burns and Smith (1982)
Bagg et al. (1981)
|Mallacouta Inlet||0.80-0.11 (PAHs)
|Bagg et al. (1981)
Maher et al. (1979)
|Rowley Shelf, WA||0.015-0.05 (dry wt.) (alkanes)||Pendoley (1992)|
|Great Barrier Reef||0.2-0.8 (dry wt.) (hydrocarbons)||Coates et al. (1986)|
Table 4: Occurrence of petroleum hydrocarbons in Australian marine biota.
|Biota||Location||Hydrocarbon Type||Concentration (mg/kg)||Reference|
|Seabirds||Brisbane River||petroleum hydrocarbons (unresolved complex mixture)||up to 1038||Miller and Connell (1980)|
|Fish||South Qld||kerosene||up to 270||Connell (1974)|
|Fish||Great Barrier Reef||hydrocarbons||up to 0.3||Coates et al. (1986)|
|Corals||Great Barrier Reef||hydrocarbons||0.06-3.1 (lipid wt.)||Coates et al. (1986)|
|Clams||Great Barrier Reef||hydrocarbons||0.06-0.1 (lipid wt.)||Coates et al. (1986)|
|Mussels||Western Port and Port Phillip Bay||petroleum||up to 4.4 (lipid wt.)||Burns and Smith (1982)|
|Oysters||Rowley Shelf (WA)||petroleum||up to 4.9 (lipid wt.)||Pendoley (1992)|
The observed occurrence of petroleum hydrocarbons in biota in Australian waters is shown in Table 4. Background concentrations are difficult to define since many animals and plants produce hydrocarbons which may be difficult to distinguish from petroleum hydrocarbons. The levels in GBR biota probably represent background levels, with corals exhibiting the highest concentrations of up to 3.1 mg/kg (lipid weight). Clearly the fish and birds from south Qld were heavily contaminated, with levels up to 270 and 1038 mg/kg, respectively . Westernport and Port Phillip Bays contain zones where biota are effectively free of contamination as well as zones where biota are contaminated . Rowley Shelf (WA) biota, as with the sediments, seems to exhibit a low level of petroleum contamination.
Oil spills of various sizes occur periodically in the Australian marine environment. Fortunately most of these have been on a small scale or have occurred in circumstances resulting in limited damage to the marine environment. For example, incidents of two relatively large spills from vessels, the Ocean Grandeur (Torres Strait) and Kirki (WA), occurred under conditions which resulted in natural dispersal of the spilled oil to the open sea. Nevertheless these larger incidents have the potential to cause immense damage, particularly to intertidal and subtidal ecosystems such as coral reefs, mangroves, seagrass communities and so on. Additionally, major spills at sea may have less obvious but serious long-term consequences for marine communities, such as detrimental effects on planktonic phases of marine organisms.
There are several reported investigations of the effects on mangrove communities in Botany Bay of smaller scale oil spills originating from oil handling facilities (Allaway et al. 1985; Anink et al. 1985; Allaway 1982). Seedling mortalities, defoliation of lower zones of trees and shrubs, mortalities of invertebrates and other adverse effects are described over areas of up to 73 hectares. These spill investigations are in accord with several controlled experiments demonstrating the toxicity of crude oils to Australian mangroves (McGuinness 1990; Wardrop et al. 1987).
Although oil spills of a relatively minor size occur frequently in GBR waters, there is a lack of any systematic investigation of their effects on coral reef ecosystems (Craik 1991). Similar oil spills occur generally throughout the Australian marine environment but there are few scientific reports on chronic or acute ecological impacts. Birds and other animals utilising surface waters, such as seals, are vulnerable to spilled oil and reports of oiled birds occasionally appear in the media (Anon 1992). In addition the toxicity of various oil spill dispersants to Australian marine biota has been demonstrated (Wardrop et al. 1987; McManus & Connell 1972). Thorhaug (1992) has recently reviewed the impact of oil spills and clean-up procedures on selected marine communities in international waters, and Miller (1982) has reviewed the lethal and sublethal effects of petroleum hydrocarbons in the marine environment.
The occurrence of different concentrations of petroleum in the marine environment was reviewed in the previous section. Adverse effects can result from the occurrence of petroleum substances in seafood. In many instances both in Australia and overseas, contamination has resulted in 'tainting', rendering the seafood unacceptable to consumers. A well known Australian example of tainting of fish, with resultant economic damage to the fishery comes, from southern Qld (Connell 1979, 1978, 1975, 1974; Shipton et al. 1970). In the 1960s sea mullet became contaminated in the Brisbane River and subsequently moved along the coast on their spawning 'run', causing tainted fish to occur along a considerable length of coast. The source of hydrocarbon contamination was an untreated sewage discharge, but the introduction of sewage treatment has essentially eliminated this problem. Any seafood listed in Table 4 as containing petroleum hydrocarbons has the potential to become tainted if concentrations of the causative substances reach high enough levels (Connell & Miller 1981a).
Petroleum hydrocarbons causing tainting usually contain a reasonable proportion of PAHs and other aromatic hydrocarbons. Many of those substances are believed to be human carcinogens (Grimmer 1983). However the dose received by consumers is usually low since contaminated seafood comprise only a small proportion of the diet of most populations (Connell & Miller 1981b).
Several responses can be expected from organisms exposed to sublethal levels of petroleum hydrocarbons. For example Chapman et al. (1988) found that gastropods exhibited reduced activity on exposure to sublethal concentrations of diesel. A range of detrimental physiological responses are possible, resulting in histopathological effects such as abnormal growth, occurrence of tumours and so on. These have not had extensive evaluation in Australian waters. Effects on larval stages of marine species may be significant: however the necessary systematic studies have not been conducted.
A range of chemical, histopathological and ecological indicators can be used to evaluate the effects of petroleum in Australian waters. The most valuable chemical indicator is the occurrence of petroleum in sediments. Water is not a satisfactory medium for monitoring, since concentrations of petroleum are very low and occurrence can be changed by weather conditions and seasonal changes. On the other hand sediments exhibit relatively high concentrations and are not affected by the factors mentioned previously.
Current results suggest that in Australian waters petroleum contamination comes from urban areas and areas where petrochemical industries operate. A national program of monitoring sediments in selected areas would be appropriate on a geographic and periodic time scale which relates to potential changes in petroleum status. In areas where elevated concentrations were detected histopathological investigations should be instituted. Should this indicate significant effects, an ecological program monitoring population, community and ecosystem effects would be appropriate.
In this work it would also be valuable to establish background information against which changes in the parameters mentioned could be evaluated. Levels of petroleum hydrocarbons and related histopathological effects which occur in a representative locations relatively free from petroleum-related activities would provide a suitable background baseline.
A publicly available national marine environment database to record this information would enhance the value of the data. It could then be used to determine management strategies in affected areas as well for the development of discharge standards and criteria.
A continued effort is needed to manage petroleum spillages and reduce them to the minimum level practicable. Specific attention is required to ensure discharge levels of petroleum from sewerage plants and industrial operations are specified in licence conditions and kept to a minimum. Little attention has been paid to urban run-off as a source of petroleum and other pollutants in Australian cities. There should be encouragement for local governments to introduce programs to improve the quality of urban run-off. While conducting these programs there is a need for the development of more soundly based standards and criteria to protect the marine environment from damage.
Petroleum spillages occur periodically in the Australian marine environment. The adverse effects of these are difficult to evaluate, but available observations indicate limited damage to mangrove ecosystems and seabirds has occurred. However spills, sewage and urban run-off contribute sublethal levels of petroleum substances to the marine environment. Elevated concentrations of petroleum occur in water, sediment and biota adjacent to urban locations or in the vicinity of petrochemical industries but are at very low levels elsewhere. These sublethal levels have had a number of adverse effects, including tainting of seafood, and have the potential to cause detrimental histopathological changes to organisms. There is a need to establish the background occurrence and effects of petroleum in some representative locations and to monitor vulnerable areas. More control and management of petroleum in sewage, industrial discharges and urban run-off is needed.
Allaway, W.G. 1982, 'Mangrove die-back in Botany Bay', Wetlands (Aust), vol. 2, pp. 2-3.
Allaway, W.G., Cole, M. & Jackson, J.E. 1985, Oil spills and mangrove die-back in Botany Bay, report to the Coastal Council of New South Wales (Australia).
Anink, P.J., Hunt, D.R., Roberts, D.E. & Jacobs, N.E. 1985, 'Oil spill in Botany Bay: short term effects and long term implications', Wetlands (Aust), vol. 5, pp. 32-34.
Anon 1992, 'Oil spill problems', Waste Management and Environment, vol. 4, p. 6.
Bagg, J., Smith, J.D. & Maher, W.A. 1981, 'Distribution of polycyclic aromatic hydrocarbons in sediments from estuaries of south-eastern Australia', Australian Journal of Marine and Freshwater Research, vol. 32, pp. 65-73.
Burns, K.A. & Smith, J.A. 1982, 'Hydrocarbons in Victorian coastal ecosystems (Australia): Chronic petroleum inputs to Westernport and Port Phillip Bays', Archives of Environmental Contamination andToxicology, vol. 11, pp. 129-140.
Burns, K.A. & Smith, J.L. 1977, 'Distribution of petroleum hydrocarbons in Westernport Bay (Australia): Results of chronic low level inputs', in Fate and Effects of Petroleum Hydrocarbons in Marine Ecosystems, National Oceanic and Atmospheric Administration and EPA, Pergamon Press, Oxford, pp. 442-453.
Burns, K.A. & Smith, J.L. 1980, 'Hydrocarbons in Victorian coastal waters', Australian Journal of Marine and Freshwater Research, vol. 31, pp. 251-256.
Burns, K.A. & Smith, J.L. 1981, 'Biological monitoring of ambient water quality: the case for using bivalves as sentinel organisms for monitoring petroleum pollution in coastal waters', Estuarine and Coastal Shelf Science, vol. 13, pp. 433-443.
Chapman, H.F., Kitching, R.L. & Hughes, J.M. 1988, 'Behavioural responses of Polinices incei (Gastropoda: Naticidae) to diesel oil contamination in sediments', Australian Journal of Marine and Freshwater Research, vol. 39, pp. 435-440.
Coates, M., Connell, D.W., Bordero, J., Miller, G.J. & Back, R. 1986, 'Aliphatic hydrocarbons in Great Barrier Reef organisms and environment' Estuarine and Coastal Shelf Science, vol. 23, pp. 99-114.
Connell, D.W. 1974, 'A kerosene-like taint in the sea mullet, Mugil cephalus (Linnaeus) I. Composition and environmental occurrence of the tainting substance', Australian Journal of Marine and Freshwater Research, vol. 25, pp. 7-24.
Connell, D.W. 1975, 'Occurrence of kerosene-like hydrocarbons in the bream, Mylio australus Gunther,Australian Journal of Marine and Freshwater Research, vol. 26, pp. 419-422.
Connell, D.W. 1978, 'A kerosene-like taint in the sea mullet Mugil cephalus (Linnaeus) II. Some aspects of the deposition and metabolism of hydrocarbons in muscle tissue, Bulletin of Environmental Contamination and Toxicology, vol. 20, pp. 492-498.
Connell, D.W. 1979, 'The case of the tainted mullet', Sea Frontiers, vol. 25, pp. 115-119.
Connell, D.W. 1990, Bioaccumulation of Xenobiotic Compounds, CRC Press, Boca-Raton, Florida.
Connell, D.W. & Hawker, D.W. 1986, 'Predicting the distribution of persistent organic chemicals in the environment', Chemistry in Australia, vol. 53, pp. 24-28.
Connell, D W & Miller, G.J. 1981a, 'Petroleum hydrocarbons in aquatic ecosystems - behaviour and effects of sublethal concentrations, Part 1', Critical Reviews in Environmental Control, vol. 11, pp. 37-104.
Connell, D.W. & Miller, G.J. 1981b, 'Petroleum hydrocarbons in aquatic ecosystems - behaviour and effects of sublethal concentrations, Part 2', Critical Reviews in Environmental Control, vol. 11, pp. 105-162.
Connell, D.W. & Schüürmann, G. 1988, 'Evaluation of various molecular parameters as predictors of bioconcentration in fish', Ecotoxicology and Environmental Safety, vol. 15, pp. 324-335.
Craik, W. 1991, 'Oil Spills in the Great Barrier Reef Region', Proceedings of 1991 International Oil Spill Conference, American Petroleum Institute, San Diego, California.
Furzer, I.A. 1975) 'Polluted muds of the Parramatta River', Search, vol. 6, pp. 39-40.
Grimmer, G. 1983, Environmental Carcinogens: Polycyclic Aromatic Hydrocarbons, CRC Press, Boca Raton, Florida.
Kayal, S.I. 1991, Occurrence and Behaviour of Polycyclic Aromatic Hydrocarbons in the Brisbane River Estuary, Ph. D. Thesis, Griffith University.
Kayal, S.I. & Connell, D.W. 1989, 'Occurrence and distribution of polycyclic aromatic hydrocarbons in surface sediments and water from the Brisbane River estuary', Estuarine and Coastal Shelf Science, vol. 29, pp. 473-487.
Kayal, S.I. & Connell, D.W. 1990, 'Partitioning of unsubstituted PAH's between surface sediments and the water column in the Brisbane River estuary', Australian Journal of Marine and Freshwater Research, vol. 41, pp. 443-456.
Maher, W.A., Bagg, J. & Smith, J.D. 1979, 'Determination of polycyclic aromatic hydrocarbons in marine sediments using solvent extraction, TLC and spectroflourimetry', International Journal of Environmental Analytical Chemistry, vol. 7, pp. 1-11.
McGuinness, K.A. 1990, 'Effects of oil spills on macro-invertebrates of saltmarshes and mangrove forests in Botany Bay, New South Wales, Australia', Journal of Experimental Marine Biology and Ecology, vol. 142, pp. 121-126.
McManus, D.A. & Connell, D.W. 1972, 'Toxicity of the oil dispersant Corexit 7664 to certain Australian marine animals', Search, vol. 3, pp. 222-224.
Miller, G.J. 1982, 'Ecotoxicology of petroleum hydrocarbons in the marine environment', Journal of Applied Toxicology, vol. 2, pp. 88-97.
Miller, G.J. & Connell, D.W. 1980, 'Occurrence of petroleum hydrocarbons in some Australian seabirds', Australian Wildlife Research, vol. 7, pp. 281-293.
Murray, A.P., Richardson, B.J. & Gibbs, C.F. 1988, Proceedings - POLMET 88 Conference, Hong Kong.
Pendoley, K. 1992, 'Hydrocarbons in Rowley Shelf (W.A.) oysters and sediments', Marine Pollution Bulletin, vol. 24, pp. 210-215.
Shipton, J, Last, J.H., Murray, K.E. & Vale, G.L. 1970' 'Studies on a kerosene-like taint in mullet (Mugil cephalus) 2. Chemical nature of the volatile constituents, Journal of the Science of Food and Agriculture, vol. 21, pp. 443-436.
Smith, J.D., Bagg, J. & Wrigley, I. 1991, 'Extractable polycyclic hydrocarbons in waters from rivers in south-eastern Australia', Water Research, vol. 25, pp. 1145-1150.
Thorhaug, A. 1992, 'Oil spills in the tropics and subtropics', in Pollution in Tropical Aquatic Systems, eds D.W. Connell & D.W. Hawker, CRC Press, Boca Raton, Florida.
Verschueren, K. 1983, Handbook of Environmental Data on Chemicals, 2nd edn, Van Nostrand Reinhold Co., New York.
Wardrop, J.A., Butler, A.J. & Johnson, J.E. 1987, 'A field study of the toxicity of two oils and a dispersant to the mangrove Avicennia marina', Marine Biology, vol. 96, pp. 151-159.
The technical contribution by Dr D. Connell was reviewed by Dr J.T. Baker, Senior AIMS Fellow, Australian Institute of Marine Science, Townsville.