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Marine litter surveillance
V o l u m e 1 2 / N u m b e r 9 / S e p t e m b e r 1981
the monitoring of slicks during a spill, as well as being of general interest. Another Paper in the series has recently been published. This deals with the use of booms in combating oil spills. A third dealing with the aerial spraying of dispersants will soon be available. Both are again illustrated with colour photographs and diagrams. Subjects being considered for future Papers include: oil collection devices; dispersants and their application; recognition and assessment of oil on shorelines; shore cleanup techniques; disposal of oil and debris from spills; sampling, analysis and identification of oils; guide to studies on biological effects; oil spill movement; and remote sensing. Of a less technical and more general nature there are such subjects as contingency planning and legal and compensation aspects. Persons wishing to obtain copies of the Papers or information on the series should contact: International Tanker Owners Pollution Federation Ltd., Staple Hail, 87-90 Houndsditch, London EC3A 7AX, UK.
Round-the-World News Saudi Arabia A spill of 7500 gallons of oil resulted when the Liberian tanker Ogden Sungari rammed and damaged a Single Buoy Mooring at Juiaymah in the Persian Gulf.
USA The accidental opening of a valve during routine washing of empty wing tanks aboard the US tanker Meton resulted in the discharge of 46000 gallons of bunker C fuel about 100 km off the Virginia Coast. The valve connected the fuel oil tanks with the empty wing tanks and before the mistake was spotted the fuel had been allowed to mix with washing effluent and drain into the sea for seven hours. 20 000 gallons of crude oil polluted the Mission River, Texas, following a leak from a corroded storage tank. The oil impacted a 72 km stretch of the river before booms were able to contain the spill.
Marine Pollution Bulletin, Vol. 12, No. 9, pp. 289-295, 1981
C025-326X/81/090289-07 $02.00/0 Pergamon Press Ltd.
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Viewpoint is a column which allows authors to express their own opinions about current events.
Marine Litter Surveillance TREVOR R. DIXON and T. J. DIXON Trevor R. Dixon is a Lecturer in Environmental Studies at the Buckinghamshire College of Higher Education and Director of the Keep Britain Tidy Group's Marine Litter Research Programme. T. J. Dixon is assisting with this programme and is a member of the Nature Conservancy Council's Seabirds at Sea Team based in Aberdeen. During the last decade there has been an increasing interest in the presence of solid wastes in the marine environment. Most reports in the literature have been concerned with the composition and distribution of plastic fragments in oceanic waters; the northern and eastern Pacific Ocean, the eastern North Atlantic Ocean and more recently the Cape Basin area of the South Atlantic. A maximum concentration of 1.771 kg km -2 has been reported. Samples collected by net tows have included polystyrene spherules and polyethylene cylinders. These have also been found in coastal waters and on beaches in many parts of the world and have been identified as the bulk materials of the plastics fabrication industry. Hence their most likely source has been attributed to wastewater discharges to rivers in industrial areas and into the sea. An alternative viewpoint, using beach observations, shows that the composition of marine litter is more varied nearer the shore. It includes primary and secondary packaging, cargo-associated and engine-room wastes as well
as fishing gear. A high proportion of these materials are discarded at sea as shipboard-generated solid wastes. These are produced in quantities ranging from 111 to 2.6 kg person-1 day-L with an additional 290 tonnes of cargo-associated wastes per ship per annum. The total amount of litter generated in the world's oceans each year, assuming all ships' solid wastes are disposed of overboard, has been estimated at 6.5 × l06 tonnes per annum. This is distributed unevenly, mostly within 400 km of land in the northern helnisphere. Marine litter levels are expected to increase with the general growth in marine traffic and our increasing use of plastic disposable (one-j ourney) packaging. The lifetimes of solid wastes in the marine environment are highly variable depending on their fabrication materials, physical conditions and rates of biological and chemical decomposition. Plastics cause most concern because of their widespread uses and intrinsic properties. These properties include low specific gravities, usually between 0.8 and 0.96, which causes them to float, they are non-biodegradable and 289
Marine PollutionBulletin only slowly photodegradable when exposed to ultra-violet radiation. Furthermore, the service lives of some thermoplastics have been extended by the incorporation of ultra-violet light stabilizers and anti-oxidants. The environmental impact of marine litter has yet to be comprehensively assessed. The most obvious impact is the aesthetic degradation of coastal amenities, particularly leisure and recreational beaches. Our knowledge of the ecological impacts of marine litter is based largely on observations from many parts of the world which have been reviewed by NAS 1975, assessing potential ocean pollutants. Larval and juvenile fish have ingested plastic particles without any apparently harmful effects although some materials block the gills of fish and crustaceans. Plastic cups have been found in the stomachs of fish caught off the south coast of England while fibreglass straps have been seen on sharks in Western Australian waters. Rubber thread cuttings have been found in the alimentary tracts of puffins Fratercula arctica, plastic fragments in gull and tern pellets and even a small toy in the gizzard of another seabird. Such items may cause local ulcerations. Mortalities of seabirds caught in discarded or lost fishing nets have been well documented. More recently there have been several reports of marine mammals becoming entangled in a variety of man-made objects. In the waters off Southern Africa, string, monofilament line, fishing net, rope, rubber rings and wire have been seen wrapped around the bodies, especially the necks, of hundreds of Cape fur seals Arctocephaluspusillus. There have been similar reports involving net fragments on whales off Newfoundland, rope collars around seals at Bird Island, South Georgia and plastic bands around northern fur seals Callorhinus ursinus in the North Pacific Ocean. In many instances the entanglements have caused injury to the victims. Human injuries, following encounters with litter on beaches, have been reported occasionally, particularly foot lacerations when bathers have trodden on discarded ring pull tabs from drinks containers or broken glass bottles. There have also been incidents involving packaged hazardous goods, lost or dumped from ships at sea and subsequently washed ashore. At Sandown, in southern England on 6 March 1976, 43 people were called to hospital for medical examinations following exposure to concentrated ethyl mercaptan fumes from a leaking, unlabelled jerrycan washed ashore. More recently 25 canisters of arsenic trichloride, which could have given off lethal fumes if exposed to the atmosphere, were washed ashore without warning onto bathing beaches in southern England. Economic losses from marine litter include the fouling of trawl nets by bottom debris, the blocking of water intake pipes by plastic sheeting and damage to ships and pleasurecraft following collisions with metal drums or wooden pallets at sea, as well as propellor fouling by floating or semi-submerged nylon ropes and net fragments.
Marine Litter Research Programme Because of the widening environmental impacts of marine litter and the absence of any international agreement to control it, the 1978 Clean World International Conference passed a resolution recommending its members 290
should do all they could to eliminate the improper disposal of litter at sea. The Keep Britain Tidy Group (the United Kingdom's litter abatement agency) responded to this initiative by extending its marine litter research programme. The aim of this research, with special reference to the British Isles, is to provide systematic data showing qualitatively and quantitatively the nature and scope of the problem. It is anticipated that such information will provide the necessary evidence to support an early introduction of proposed control measures, such as those contained in Annexe V of the 1973 MARPOL Convention as amended by 1978 Protocol. Furthermore, the development of a marine litter surveillance system would enable an evaluation of the effectiveness of such controls, if they are introduced, by monitoring changes. The immediate objectives of the programme are: (1) The development of standardized field survey techniques and analytical methods for the surveillance of marine litter by beach surveys; (2) The identification of major trends in the composition, distribution and origin of litter occurring in the coastal and oceanic waters of Western Europe. The programme began in 1973 with a study of marine litter on a Kent beach and the initial development of surveillance methods. The second stage was completed by 1980 following area studies of beach litter on the shores of the English Channel at the Cherbourg Peninsula (France) and North Sea at West Jutland (Denmark). The third stage, also completed in 1980, followed observations of beach litter by volunteers at 797 coastal sites in the British Isles. Subsequent stages will include further area studies on the shores of the North Atlantic Ocean in Portugal and around the Western Isles of Scotland.
Method of Approach To date three approaches have been used to investigate the composition, quantity and distribution of litter in the marine environment. The first approach was to estimate the types and quantities of solid wastes generated aboard ships and pleasurecraft. This was accomplished by multiplying the number of people at sea in a given activity by the average amounts of solid wastes that the activity generates. Sample values were extrapolated to estimate total inputs of litter into the marine environment. The major limitation of this approach is the validity of assumptions regarding the composition of the world fleet of ships and pleasurecraft, the sizes of ships and their crews, the types and quantities of solid wastes generated and the fate of these materials. Interpretation of these data required caution. The second approach was observations on or collections of surface floating litter at sea. This method of litter assessment is dependent on suitable weather and sea conditions which inevitably lead to high costs in expenditure and effort to achieve a representative sample over a large enough area. The third approach is beach surveys which are known to give a distorted picture of the composition of marine litter. This is due to the varying fate of materials following discard at sea. Vegetable matter, paperboard and fibreboard items
Volume 12/Number 9/September 1981
tend to degrade rapidly at sea; they are not therefore usually visible in significant quantities on the shore although they constitute a large proportion of discards at sea. Other materials may settle on the sea floor, be ingested by marine organisms or become suspended in the water column. There can also be considerable confusion regarding the sources of beach litter, some originating from local discards by holidaymakers and other items reaching the shore from land-based sources via nearby rivers and outfalls. Despite the inherent biases of beach surveys, this method of approach was adopted in the marine litter research programme for the following reasons: (1) Sampling constraints are more easily overcome because representative areas of shoreline can be surveyed more easily and accurately than water masses and under most weather conditions; (2) Litter tends to accumulate on beaches, therefore statistically viable samples can be collected at any given time, thereby avoiding uncertain extrapolations from small samples; (3) Durable non-floating items of litter may ultimately become stranded on the shore and can therefore be incorporated into composition assessments which cannot be accomplished in any other way.
Selection of study areas In selecting study areas for beach surveys of marine litter, careful consideration should be given to a variety of physical and anthropogenic parameters. Prevailing winds are known to be important in transporting surface pollutants. Hence study areas were selected where the directions of prevailing winds and surface residual currents are onshore. Uusually, surveys were timed to coincide with periods of onshore winds. Beach type is another important parameter. Containers of different fabrication material and dimension remain stranded on moderate to low energy sandy beaches for consistently longer periods than high energy shingle beaches. Hence sandy beaches characterized by wide reach zones and shallow beach face gradients where litter might be expected to accumulate were surveyed. Study areas have also been chosen on the basis of their close proximity to maj or shipping routes or fishing grounds and therefore close to the points of marine litter discharge. Selection of sampfing sites The main consideration is that sample sites should be selected randomly, for statistical analyses of resultant data and uniformity of beach topography for data comparability. A semi-random method of stratified sampling is employed for sample site selection. Study areas are divided into varying numbers of enumeration areas on the basis of the beach characteristics already outlined. Potential sampling sites are identified by the degree of accessibility to the shore and their remoteness from landgenerated litter sources, such as bathing or camping areas. The sites surveyed are then randomly selected from the total number of potential sites in each enumeration area. Ideally the position of shore sampling sites should be selected randomly, but in practice subjective judgements are made on the basis of the amounts of litter on the beach face. Frequently the quantities of litter are too great to sample within the constraints of available time and personnel.
Sampling methods and data collection In area surveys two sampling methods are employed. At each sample site three 5 m wide belt transects are established at right angles to the shore using measuring tapes and markers. Each transect extends across the foreshore to include all visible high water marks with an additional 30 m shorewards section extending into the foredunes of the backshore zone where litter removed from the shore by wind action accumulates. The following data are recorded from litter accumulations along each transect: (1) Total wet weights of the main fabrication materials and the densities of litter in each foreshore transect, excluding items over 15 kg and timber; (2) Item frequency, fabrication materials, geographical origins, ages and original contents of containers; (3) The distribution of plastic fragments by their presence or absence in 1 m square plots along the transect line. More extensive searches are employed to collect samples of containers for dating. At each site 2-4 observers walk along the foreshore parallel to high water marks for a distance of approximately l km. All containers are examined and suitable specimens collected. The procedure is then repeated in the foredunes of the backshore zone at each site. Two methods of dating containers are employed: relative dating based upon frequent changes in container designs or markings, knowing the period of manufacture of each type; absolute dating from the interpretation of individual date codes marked on containers and showing their dates of manufacture. Methods of identifying container contents, fabrication materials and geographical origins have been discussed in earlier papers.
The Characteristics of Litter on West European Beaches Having developed a system capable of assessing the problems of marine litter on beaches, what signs are there that international measures are required to reduce its impact? The analysis of data collected so far show several features which suggest that marine litter has lost its national identity and joined the multinationals. Several recurrent trends in the composition, ages and distributions of litter have been identified from surveys completed to date. The composition of litter on beaches is diverse; the main constituents being containers of all types and sizes, polythene sheeting, rope, wire, fibreboard, paperboard, light bulbs, fishing gear, out-dated pyrotechnics, packaged hazardous goods and occasionally partly used drugs (Table 1). The mean foreshore density from 150 transects on the beaches of the Cherbourg Peninsula, excluding items over 15 kg, was 27.14 g m -2. The corresponding value for West Jutland beaches was 103 g m-2 for 120 transects. Containers made from plastics, glass, metal and wood accounted for over 80°7o of beach litter samples by weight. Of these, more than 44°7o were plastics, mostly high and low density polyethylene moulded bottles and smaller numbers of polyvinylchloride and polystyrene containers. The original contents of plastic containers collected from sampling sites on a selection of West European beaches are shown in Table 2. Lavatory cleaner and household cleaner 291
Marine Pollution Bulletin
TABLE 1
TABLE 3
Partly used drugs found on a 3 km stretch of beach at Sandwich Bay, Kent, 1978-1979.
The geographical origins of container samples collected from west European beaches (percentage of the identified sample).
Product name Magnacid Pulver *Aspirine U P S A
Drug or type
Country of origin
Magnesium silicate powder/antacid
Netherlands
Acetylsalicylic acid (Aspirin tablets)
France
Sandwich Cherbourg West U.K.National Bay, Kent Peninsula Jutland Survey 1973-1976 August 1978 April 1979 1978-1979 Sample number (n)
989*
1619
2079
6410¢
United Kingdom
28.6
36.3
51.5
71.0
France
24.2
34.7
10.4
10.5
Antibiotic/cortisone (eardrops)
Brazil
Benelux
21.5
8.8
8.3
5.1
Antimalaria tablets
United Kingdom
West Germany
12.6
7.7
8.5
4.4
Deltarhinol
Corticosteroid nose drops
Belgium
Mylanta
Antacid-antiflatulent
USA
Aft-B-Total
Vitamin B Complex tablets Norway
Other European countries (excluding USSR)
Otomicina *Paludrine
10.6
6.6
12.2
5.9
North and South America
1.8
2.8
4.9
1.2
0.4
1.4
1.7
1.0
0.3
1.1
1.7
0.5
Purganol Daguin
Laxative tablets
France
Albyl Setlers
Aspirin tablets
Sweden
Unknown
Sulphadimidine tablets
Netherlands
Asia (including USSR)
Codeine tablets
Netherlands
Oceania
*Calcipen Leo
Penicillin tablets
Scandinavia
Africa
*Pfizers Terramycin
Antibiotic
Unknown
Total
*Kodinfentabletter
Biseririte tablets *Riabal tablets
Antacid tablets
West Germany
Anticholinergic agent
France
Vitamin C tablets
Spain
*Pirocrid
Protizinic acid
France
*Tetrabromethan
Tetrabromathene
West Germany
*Benadryl Capsules
Antihistamine
USA
*J uvapyrin Dolder
Anti-pyretic and analgesic
Switzerland
*Ovran
Oral contraceptive tablets
United Kingdom
Redoxon tablets
*Medium to high hazard rating based on the quantity found and its toxicity if taken orally,
bottles, with capacities ranging from 0.2 to 4.5 I. occupy the first and second rank orders of abundance in each sample. Other containers frequently found include wooden and plastic fish boxes, metal drums of petroleum products, especially marine diesel and lubricating oils, paperboard milk cartons and glass spirits bottles. The original contents of container samples collected from the beaches of the Cherbourg Peninsula and West Jutland were compared statistically. There was no significant difference.
TABLE 2 The original contents of plastic container samples collected from west European beaches (percentage of the total sample). Sandwich Cherbourg West U.K.National Bay, Kent Peninsula Jutland Survey 1973-1976 August 1978 April 1979 1978-1979 Sample number (n)
1134
1378
1259
8381
Lavatory cleanser
30.4
19.5
15.7
11.9
Household cleaners
16.4
14.0
19.1
11.7
Mineral waters
9.4
9.1
5.1
2.2
Dairy products (excluding milk)
3.8
5.1
3.1
7.2
Cosmetics and toiletries
6.8
4.3
3.6
3.1
Milk
4.5
8.5
7.0
3.6
Wine
5.5
7.5
2.3
0.3
Others
16.7
18.8
24.9
9.8
6.5
13.4
19.4
50.5
Unidentified Total
292
100
100
100
100
0 100
0.6 100
0.8 100
0.5 100
*Plastic containers only. l- Plastic and metal containers only.
A comparison of the geographical origins of container samples collected from Cherbourg and West Jutland beaches, shown in Table 3, also showed that there was no significant difference. In each sample there was a global scale of container manufacturing sites, including specimens from Australia, Brazil, Canada, China, Japan, South Africa, USA, USSR, Venezuela and New Zealand. In order to assess the persistence of litter in the marine environment, the ages of container samples fabricated from various materials have been deduced. The criteria for selecting specimen brands for dating include the following: (1) they have been marketed continuously for more than 10 years in disposable (one-journey) packages; (2) they are usually market leaders for each type of product including lavatory cleansers, household cleaners, long life milk and spirits; (3) they are usually marketed in large quantities (8-10 x 106 units per annum) in several countries. Relative dating methods show that more than 85°7o of each of four container samples collected from West European beaches have been current production types. Absolute dating of smaller samples has shown that more than 68°7o are less than 4 years old (Table 4). This would suggest that plastic containers, particularly those made from high density polyethylene, are relatively short lived contaminants of the marine environment, if a dating scale in years is regarded as small. Some trends have been deduced concerning the fate of plastic bottles in the marine environment. Fragmented specimens were found in sample collections on the French and Danish beaches with frequencies of 17.7% and 15.7% respectively. They were more prominent in bottle samples collected from backshore than foreshore locations. Statistical analysis showed that for each study area disproportionately higher frequencies of older plastic containers, those over 4 years, were fragmented. Also these older plastic containers were more prominent in samples collected from backshore rather than foreshore locations.
Volume 12/Number 9/September 1981 TABLE 4 Age of container samples collected from west European beaches (cumulative percentages). Sandwich Bay, Kent 1973-1976
Cherbourg Peninsula August 1978
240*
802
954
0- l
47.5
22.9
24.8
12.2
l- 2
84.2
61.7
63.6
32.0
2- 3
92.1
77.9
78.3
58.1
3 -4
97.9
85.8
84.9
68.6
Sample number (n)
West U.K.National Jutland survey April1979 1978-1979 188
Age (years)
4- 5
100
92.5
89.9
80.4
5 -6
100
94.5
95.0
85.1
6- 7
100
95.5
97.1
87.8
7 --8
100
96.5
97.8
91.6
8 -9
100
97.3
98.5
94.8
9 - 10 10 - 11
100 100
98.5 99.1
98.9 99.5
95.8 97.9
11 - 12
100
99.6
99.6
98.5
12 - 13
100
13 - 14
100
99.8 100
99.8
99.5
100
100
*Sample of 240 polyethylene bottles.
This field evidence suggests that bottles made from the major thermoplastics, especially high density polyethylene, are photodegradable out of water. Photodegradation causes the embrittlement of plastics followed by fragmentation, probably within 2 years of them being discarded in West European waters. If there is an accumulation of plastic bottles, it is of a duration of less than 2 years and takes place beyond the reach of normal wave action in the backshore zones of beaches. Differences in the rates of degradation of plastic, glass and paperboard containers appears to be minimal when the mean ages of samples with individual date codes are compared (Table 5).
TABLE 5 The mean ages of container samples fabricated from different materials. Cherbourg Peninsula August 1978 Glass* Paperboard t Plastics $
2.50 1.07 2.95
ll3 44 645
0.10 0.04 0.09
West Jutland April 1979 2.17 1.17 2.86
108 35 811
0.09 0.06 0.07
~ Mean age in years. n Sample size. ag Standard error of sample mean. * Mostly white flint spirits bottles. t Mainly milk cartons. ~: Mostly high density polyethylene bottles.
Another major concern is the widespread distributions of marine litter, especially plastic fragments, in the areas surveyed. Plastic pieces were found in 94% of transects on the French and Danish beaches, and were generally distributed across both foreshore and backshore zones. In the United Kingdom national survey plastic fragments were reported at 77.8% of the 797 sample sites, compared with frequencies of 34.2% for oil, 62.7O/o for wood (including driftwood) and 84.8% for one or more plastic containers. It has yet to be established whether the plastic fragments originate from photodegraded plastic bottles in situ.
The trends in composition and geographical origin of container samples indicates that the source of discard is ships and pleasurecraft at sea. More direct evidence of this source is frequently available in the form of out-dated pyrotechnics and lifeboat rations, fishing gear, drug containers bearing the names of ships' dispensing chemists and labels on spirits bottles indicating that the contents are to be consumed only by ships' crews. Although holidaymakers contribute to beach litter, this is usually only during the summer months and in locations with easy access by road. The composition of discards originating from this source is characterized by a high proportion of metal drinks containers, especially metallic with ring pull tops. These are generally evenly distributed across foreshore and backshore zones of beaches.
Marine Litter Controls At the moment there are few, if any, effective means of controlling or preventing litter dumping. In some parts of the world marine litter levels have been high enough to warrant beach cleaning operations. The extent of such remedial action and the costs incurred have yet to be determined. In parts of the Eastern Mediterranean ground nut harvesters have been adapted for use as beach cleaners. Elsewhere, larger purpose-built machines have been developed, the latest weighing 23 tonnes and capable of cleaning up to 2 hectares of shore an hour. Usually, to justify expenditure, only the most popular bathing beaches are cleaned regularly during the summer season. Hence beach cleaning is unlikely to have any significant effect upon the present levels or distributions of marine litter. A more worrying aspect of litter appearing on beaches was illustrated recently in southern England where local authorities are having to collect and safely dispose of a variety of packaged hazardous chemicals which are now regularly washed ashore. Clearance operations on the Isle of Wight have cost up to £8000 per annum. This expenditure has not been recovered in accordance with the "polluter pays" principle because, in most cases, package labels have been lost and consequently the owners or shippers of the materials cannot be identified. Other issues, concerning compensation and liability arrangements following beach pollution by packaged hazardous goods lost from ships at sea, have been discussed in earlier papers. The available evidence suggests preventative measures are the only effective means of controlling litter in both terrestrial and marine environments. As packaging is a major constituent of litter, changes in the types and uses of packaging have been proposed and in some cases implemented. But on a small scale one approach has been to limit or even prohibit the use of certain types of disposable packaging. For example, in Denmark the uses of metal beverage containers are already restricted and they will not be used for the home market from 1982. Plastics materials, which are the major constituent of packaging and hence litter, have been developed with enhanced degradability. The three major thermoplastics packaging materials can be made to degrade faster on exposure to ultra-violet light. This has been accomplished by compounding existing components with photosensitive additives or by the incorporation of minor amounts of 293
Marine Pollution Bulletin
comonomers containing photosensitive groups. It has been established that a bottle made from one of these materials will degrade to a fragmentable condition within 3 months compared with 3 years for its unmodified counterpart. If plastics with enhanced degradability are used extensively for packaging, they may well reduce the persistence of these materials in the marine environment but any benefits could well be offset by increases in the quantities used and therefore disposed of at sea. The evidence available suggests that enhanced degradability plastics would not be a commercial success because: (1) They prevent the re-use of packaging materials by encouraging further development of disposable ones; (2) There are technical problems in ensuring that degradation will not occur during the required life of the new materials; (3) It remains to be established whether new materials prevent any toxic or tainting hazards during use, particularly when used in food packaging, or ecological hazards after disposal; (4) The new materials are expected to cost more than their unmodified counterparts, and this may well reduce their commercial and social acceptance. All of these arguments are contested by the manufacturers of rapidly degrading plastics. Akerlund & Hausing of Sweden, the manufacturers of "Ende-plast", which degrades by natural photochemical, thermal and microbiological action when exposed to ultra-violet radiation, claim that the additives are harmless to mankind and the environment, as also are the end products of degradation, so that no adverse reaction of any kind may be expected from their use. With increased raw material costs the makers of conventional plastics are pursuing various ideas to conserve raw materials. If these ideas are implemented the environmental impacts of plastic materials could well be reduced at a point higher up the chain than the main culprit, the consumer. A new approach by plastic manufacturers includes: (l) Reducing container weights by using a foam structure; (2) Incorporating suitable extenders which are cheaper than base polymers; (3) Reducing container wall thicknesses; (4) Using multi-layer structures of various plastics materials; (5) Using biaxial orientation of the base polymer such as polyethylene terephthalate (PET) which is presently used for carbonated beverage containers. Failing these moves, which would presumably be financially controlled, a more direct preventative approach is to reduce or eliminate inputs of litter into the marine environment from ships. At the present time the routine disposal of shipboard-generated solid wastes at sea does not constitute an offence under IMCO Conventions in force. However, Annexe V of the 1973 MARPOL Convention, as amended by the 1978 Protocol, does contain provisions regarding the disposal of shipboardgenerated garbage and the prevention of this type of pollution. These provisions state: (1) The disposal of plastics materials anywhere at sea is prohibited; (2) The disposal of other garbage including paper products, glass, metal and bottles is to be more than 12 294
nautical miles from the nearest land, unless passed through a comminuter or grinder, and 25 nautical miles for dunnage, lining and packing materials which will float; (3) Governments that are Parties to the Convention are urged to take appropriate action to ensure the enforcement of the provisions, as early as possible, by providing adequate facilities for the reception of garbage from ships. Unfortunately the effectiveness of these proposals in real terms is questionable. Firstly, Annexe V of the MARPOL Convention is optional and not an obligatory annexe and therefore this intentional distinction may well delay the implementation of the regulations contained in it. Secondly, economic, technical and legal difficulties have been reported which will affect the implementation of the proposals; for example, the types of solid waste storage or disposal systems used by ships on long haul routes. Systems have not yet been developed which can process shipboard-generated solid wastes to the point of zero discharge of waste into the sea. In particular the segregation and disposal of plastics materials is expected to be a major difficulty within the constraints of available time and space. Problems have also been reported with the use of compactors to store wastes, primarily poor reliability and unsatisfactory sanitary standards. Thirdly, it has yet to be established whether ports can provide the necessary facilities for disposal ashore of shipboardgenerated solid wastes. Some ports and even states still insist that ships' garbage is disposed of at sea as a public health measure. Fourthly, it will be difficult, if not impossible, to enforce the regulations governing the disposal of wastes at sea. Lastly, the economic implications regarding the construction of reception facilities, the equipment requirements of existing ships and the training of personnel have yet to be fully explored. Despite these apparently intractable problems some progress has been made on short sea routes following the introduction of voluntary codes of practice. The large United Kingdom ferry operators Sealink (UK) and Townsend-Thoresen now store most shipboard-generated solid wastes, other than food wastes, in compactors for disposal ashore. The equipment used has met the required operating standards and has proved to be very reliable. With regard to hazardous wastes the United Kingdom's Department of Trade has recognized the dangers and serious consequences of pyrotechnics if they are found and improperly handled by members of the public, especially children. Consequently, in a notice to mariners (Merchant Shipping Notice - M 787, November 1976, Disposal of outof-date pyrotechnics) guidelines have been laid down for the correct disposal of these items from UK registered ships. Another recommendation urges Masters and Shipowners to report incidents involving losses of packaged hazardous goods at sea (Merchant Shipping Notice M 953. Reports on incidents involving packaged dangerous goods). This is in addition to the existing IMCO Cargo Loss Reporting Scheme which has proved inadequate as an early warning system to prevent beach pollution by these materials. This recommendation was due largely to recent incidents involving packaged hazardous chemicals washed ashore onto the beaches of southern England following losses from ships at sea. Unilateral actions of this type by the United
Volume12/Number9/September 1981 Kingdom will have limited success because it can only apply to 10-15 % of coastal traffic around the British Isles. In the absence of any effective marine litter controls at the present time and probably during much of the next decade, litter abatement agencies and environmental pressure groups are initiating campaigns to try and correct the situation. In the United Kingdom the Keep Britain Tidy
Group is promoting voluntary codes of practice, which apply to all seacraft, which seek to eliminate the disposal of litter at sea. More research will be undertaken to assess the environmental impacts of marine litter and establish a quantitative basis for a comprehensive surveillance system. The pollutants change with progress but the proximate cause is unaltered.
Marine Pollution Bulletin, Vol. 12, No. 9, pp. 295-301, 1981 Printed in Great Brilain
0025 - 326X / 81/090295--07 $02.00/0 © 1981 Pergamon Press Ltd.
Present State of Oil Pollution in the Northern Indian Ocean R. SEN GUPTA and TARIQ W. KUREISHY National Institute o f Oceanography, Dona Paula, Goa 403004, India
A consolidated picture of oil pollution for the northern Indian Ocean is presented. Oil slicks were sighted on 5582 observations, about 83.5% of the total observations of 6689. The range of concentrations, of the floating tar balls, is 0-6.0 mg/m 2 in the Arabian Sea. Similarly, the oil tanker route in the Bay of Bengal has the range of 0-69.75 mg/m 2. North of this route, the Bay of Bengal is comparatively free from this floating tar. Mean concentrations of dissolved and dispersed hydrocarbons for 0-20 m are 32.5 and 24.1 ~g kg -t, respectively, in the Arabian Sea and the Bay of Bengal.
Since the initiation of Marine Pollution (Petroleum) Monitoring Pilot Project (MAPMOPP) of the Integrated Global Ocean Station System (IGOSS), several reports on the progress of the project and the state of oil pollution in different ocean areas of the world have been published (Sleeter et al., 1974, 1976; Levy & Walton, 1976; Wong et al., 1976; Levy, 1979, 1980; Suzuoki & Shirakawa, 1979; Sano et al., 1979; Shigehara et al., 1979; Gerard, 1979; Kohnke, 1980; Sobchenko et al., 1980; Oostdam, 1980). Most of these reports analysed the data collected from specific areas. Only two reports (Kohnke, 1980; Levy, 1980) cover all the oceanic areas and include the data collected by all the participating countries on the three MAPMOPP parameters, i.e. visual observations of oil slicks and other floating pollutants, particulate petroleum residues (tar balls), and dissolved and dispersed hydrocarbons. Data from a few series of observations from the Arabian Sea and the Bay of Bengal, mainly from the two oil tanker routes across them, have been published recently (Sen Gupta et al., 1978, 1980; Qasim & Sen Gupta, 1980; Fondekar et al., 1980). These reports have mainly dealt with the dissolved
and dispersed hydrocarbons and no attempt has been made so far to present a consolidated picture of oil pollution, covering all the MAPMOPP parameters, in the Indian Ocean incorporating the data collected by all the participating countries in the region. This report is an attempt to present an analysis of the data collected from the Indian Ocean during MAPMOPP. Since the data available with the Japan Oceanographic Data Centre, which was nominated as Responsible National Oceanographic Data Centre (RNODC) for the Indian Ocean region by IGOSS, covered only the area north of the equator (Fig. 1), this report is entitled 'Present State of Oil Pollution in the northern Indian Ocean". Data on all the three MAPMOPP parameters, collected from this area up to June 1980, are analysed in detail in this report. The areas covered are 00-30 ° N and 50°-100 ° E for oil slicks and 5 °20 ° N amd 69 °-99 ° E for floating tar and dissolved/dispersed hydrocarbons. The fourth MAPMOPP parameter, beach tar, is not included in this report since these results have been published earlier (Dhargalkar etal., 1977). India, Thailand and Malaysia are the three countries most actively participating in this project in the Indian Ocean region. While India has submitted to Japan RNODC data on all the three parameters from 1977 onwards, Thailand has submitted data on dissolved and dispersed hydrocarbons from 1978 and Malaysia data on oil slicks and other floating pollutants from 1979. However, the number of participating countries from the region is gradually increasing. A total of 6689 observations of oil slicks and other floating pollutants, collected by ships from the participating countries in the region and by many other merchant ships participating in the 'Ships of Opportunity' programme of 295
the monitoring of slicks during a spill, as well as being of general interest. Another Paper in the series has recently been published. This deals with the use of booms in combating oil spills. A third dealing with the aerial spraying of dispersants will soon be available. Both are again illustrated with colour photographs and diagrams. Subjects being considered for future Papers include: oil collection devices; dispersants and their application; recognition and assessment of oil on shorelines; shore cleanup techniques; disposal of oil and debris from spills; sampling, analysis and identification of oils; guide to studies on biological effects; oil spill movement; and remote sensing. Of a less technical and more general nature there are such subjects as contingency planning and legal and compensation aspects. Persons wishing to obtain copies of the Papers or information on the series should contact: International Tanker Owners Pollution Federation Ltd., Staple Hail, 87-90 Houndsditch, London EC3A 7AX, UK.
Round-the-World News Saudi Arabia A spill of 7500 gallons of oil resulted when the Liberian tanker Ogden Sungari rammed and damaged a Single Buoy Mooring at Juiaymah in the Persian Gulf.
USA The accidental opening of a valve during routine washing of empty wing tanks aboard the US tanker Meton resulted in the discharge of 46000 gallons of bunker C fuel about 100 km off the Virginia Coast. The valve connected the fuel oil tanks with the empty wing tanks and before the mistake was spotted the fuel had been allowed to mix with washing effluent and drain into the sea for seven hours. 20 000 gallons of crude oil polluted the Mission River, Texas, following a leak from a corroded storage tank. The oil impacted a 72 km stretch of the river before booms were able to contain the spill.
Marine Pollution Bulletin, Vol. 12, No. 9, pp. 289-295, 1981
C025-326X/81/090289-07 $02.00/0 Pergamon Press Ltd.
Printed in Great Britain.
Viewpoint is a column which allows authors to express their own opinions about current events.
Marine Litter Surveillance TREVOR R. DIXON and T. J. DIXON Trevor R. Dixon is a Lecturer in Environmental Studies at the Buckinghamshire College of Higher Education and Director of the Keep Britain Tidy Group's Marine Litter Research Programme. T. J. Dixon is assisting with this programme and is a member of the Nature Conservancy Council's Seabirds at Sea Team based in Aberdeen. During the last decade there has been an increasing interest in the presence of solid wastes in the marine environment. Most reports in the literature have been concerned with the composition and distribution of plastic fragments in oceanic waters; the northern and eastern Pacific Ocean, the eastern North Atlantic Ocean and more recently the Cape Basin area of the South Atlantic. A maximum concentration of 1.771 kg km -2 has been reported. Samples collected by net tows have included polystyrene spherules and polyethylene cylinders. These have also been found in coastal waters and on beaches in many parts of the world and have been identified as the bulk materials of the plastics fabrication industry. Hence their most likely source has been attributed to wastewater discharges to rivers in industrial areas and into the sea. An alternative viewpoint, using beach observations, shows that the composition of marine litter is more varied nearer the shore. It includes primary and secondary packaging, cargo-associated and engine-room wastes as well
as fishing gear. A high proportion of these materials are discarded at sea as shipboard-generated solid wastes. These are produced in quantities ranging from 111 to 2.6 kg person-1 day-L with an additional 290 tonnes of cargo-associated wastes per ship per annum. The total amount of litter generated in the world's oceans each year, assuming all ships' solid wastes are disposed of overboard, has been estimated at 6.5 × l06 tonnes per annum. This is distributed unevenly, mostly within 400 km of land in the northern helnisphere. Marine litter levels are expected to increase with the general growth in marine traffic and our increasing use of plastic disposable (one-j ourney) packaging. The lifetimes of solid wastes in the marine environment are highly variable depending on their fabrication materials, physical conditions and rates of biological and chemical decomposition. Plastics cause most concern because of their widespread uses and intrinsic properties. These properties include low specific gravities, usually between 0.8 and 0.96, which causes them to float, they are non-biodegradable and 289
Marine PollutionBulletin only slowly photodegradable when exposed to ultra-violet radiation. Furthermore, the service lives of some thermoplastics have been extended by the incorporation of ultra-violet light stabilizers and anti-oxidants. The environmental impact of marine litter has yet to be comprehensively assessed. The most obvious impact is the aesthetic degradation of coastal amenities, particularly leisure and recreational beaches. Our knowledge of the ecological impacts of marine litter is based largely on observations from many parts of the world which have been reviewed by NAS 1975, assessing potential ocean pollutants. Larval and juvenile fish have ingested plastic particles without any apparently harmful effects although some materials block the gills of fish and crustaceans. Plastic cups have been found in the stomachs of fish caught off the south coast of England while fibreglass straps have been seen on sharks in Western Australian waters. Rubber thread cuttings have been found in the alimentary tracts of puffins Fratercula arctica, plastic fragments in gull and tern pellets and even a small toy in the gizzard of another seabird. Such items may cause local ulcerations. Mortalities of seabirds caught in discarded or lost fishing nets have been well documented. More recently there have been several reports of marine mammals becoming entangled in a variety of man-made objects. In the waters off Southern Africa, string, monofilament line, fishing net, rope, rubber rings and wire have been seen wrapped around the bodies, especially the necks, of hundreds of Cape fur seals Arctocephaluspusillus. There have been similar reports involving net fragments on whales off Newfoundland, rope collars around seals at Bird Island, South Georgia and plastic bands around northern fur seals Callorhinus ursinus in the North Pacific Ocean. In many instances the entanglements have caused injury to the victims. Human injuries, following encounters with litter on beaches, have been reported occasionally, particularly foot lacerations when bathers have trodden on discarded ring pull tabs from drinks containers or broken glass bottles. There have also been incidents involving packaged hazardous goods, lost or dumped from ships at sea and subsequently washed ashore. At Sandown, in southern England on 6 March 1976, 43 people were called to hospital for medical examinations following exposure to concentrated ethyl mercaptan fumes from a leaking, unlabelled jerrycan washed ashore. More recently 25 canisters of arsenic trichloride, which could have given off lethal fumes if exposed to the atmosphere, were washed ashore without warning onto bathing beaches in southern England. Economic losses from marine litter include the fouling of trawl nets by bottom debris, the blocking of water intake pipes by plastic sheeting and damage to ships and pleasurecraft following collisions with metal drums or wooden pallets at sea, as well as propellor fouling by floating or semi-submerged nylon ropes and net fragments.
Marine Litter Research Programme Because of the widening environmental impacts of marine litter and the absence of any international agreement to control it, the 1978 Clean World International Conference passed a resolution recommending its members 290
should do all they could to eliminate the improper disposal of litter at sea. The Keep Britain Tidy Group (the United Kingdom's litter abatement agency) responded to this initiative by extending its marine litter research programme. The aim of this research, with special reference to the British Isles, is to provide systematic data showing qualitatively and quantitatively the nature and scope of the problem. It is anticipated that such information will provide the necessary evidence to support an early introduction of proposed control measures, such as those contained in Annexe V of the 1973 MARPOL Convention as amended by 1978 Protocol. Furthermore, the development of a marine litter surveillance system would enable an evaluation of the effectiveness of such controls, if they are introduced, by monitoring changes. The immediate objectives of the programme are: (1) The development of standardized field survey techniques and analytical methods for the surveillance of marine litter by beach surveys; (2) The identification of major trends in the composition, distribution and origin of litter occurring in the coastal and oceanic waters of Western Europe. The programme began in 1973 with a study of marine litter on a Kent beach and the initial development of surveillance methods. The second stage was completed by 1980 following area studies of beach litter on the shores of the English Channel at the Cherbourg Peninsula (France) and North Sea at West Jutland (Denmark). The third stage, also completed in 1980, followed observations of beach litter by volunteers at 797 coastal sites in the British Isles. Subsequent stages will include further area studies on the shores of the North Atlantic Ocean in Portugal and around the Western Isles of Scotland.
Method of Approach To date three approaches have been used to investigate the composition, quantity and distribution of litter in the marine environment. The first approach was to estimate the types and quantities of solid wastes generated aboard ships and pleasurecraft. This was accomplished by multiplying the number of people at sea in a given activity by the average amounts of solid wastes that the activity generates. Sample values were extrapolated to estimate total inputs of litter into the marine environment. The major limitation of this approach is the validity of assumptions regarding the composition of the world fleet of ships and pleasurecraft, the sizes of ships and their crews, the types and quantities of solid wastes generated and the fate of these materials. Interpretation of these data required caution. The second approach was observations on or collections of surface floating litter at sea. This method of litter assessment is dependent on suitable weather and sea conditions which inevitably lead to high costs in expenditure and effort to achieve a representative sample over a large enough area. The third approach is beach surveys which are known to give a distorted picture of the composition of marine litter. This is due to the varying fate of materials following discard at sea. Vegetable matter, paperboard and fibreboard items
Volume 12/Number 9/September 1981
tend to degrade rapidly at sea; they are not therefore usually visible in significant quantities on the shore although they constitute a large proportion of discards at sea. Other materials may settle on the sea floor, be ingested by marine organisms or become suspended in the water column. There can also be considerable confusion regarding the sources of beach litter, some originating from local discards by holidaymakers and other items reaching the shore from land-based sources via nearby rivers and outfalls. Despite the inherent biases of beach surveys, this method of approach was adopted in the marine litter research programme for the following reasons: (1) Sampling constraints are more easily overcome because representative areas of shoreline can be surveyed more easily and accurately than water masses and under most weather conditions; (2) Litter tends to accumulate on beaches, therefore statistically viable samples can be collected at any given time, thereby avoiding uncertain extrapolations from small samples; (3) Durable non-floating items of litter may ultimately become stranded on the shore and can therefore be incorporated into composition assessments which cannot be accomplished in any other way.
Selection of study areas In selecting study areas for beach surveys of marine litter, careful consideration should be given to a variety of physical and anthropogenic parameters. Prevailing winds are known to be important in transporting surface pollutants. Hence study areas were selected where the directions of prevailing winds and surface residual currents are onshore. Uusually, surveys were timed to coincide with periods of onshore winds. Beach type is another important parameter. Containers of different fabrication material and dimension remain stranded on moderate to low energy sandy beaches for consistently longer periods than high energy shingle beaches. Hence sandy beaches characterized by wide reach zones and shallow beach face gradients where litter might be expected to accumulate were surveyed. Study areas have also been chosen on the basis of their close proximity to maj or shipping routes or fishing grounds and therefore close to the points of marine litter discharge. Selection of sampfing sites The main consideration is that sample sites should be selected randomly, for statistical analyses of resultant data and uniformity of beach topography for data comparability. A semi-random method of stratified sampling is employed for sample site selection. Study areas are divided into varying numbers of enumeration areas on the basis of the beach characteristics already outlined. Potential sampling sites are identified by the degree of accessibility to the shore and their remoteness from landgenerated litter sources, such as bathing or camping areas. The sites surveyed are then randomly selected from the total number of potential sites in each enumeration area. Ideally the position of shore sampling sites should be selected randomly, but in practice subjective judgements are made on the basis of the amounts of litter on the beach face. Frequently the quantities of litter are too great to sample within the constraints of available time and personnel.
Sampling methods and data collection In area surveys two sampling methods are employed. At each sample site three 5 m wide belt transects are established at right angles to the shore using measuring tapes and markers. Each transect extends across the foreshore to include all visible high water marks with an additional 30 m shorewards section extending into the foredunes of the backshore zone where litter removed from the shore by wind action accumulates. The following data are recorded from litter accumulations along each transect: (1) Total wet weights of the main fabrication materials and the densities of litter in each foreshore transect, excluding items over 15 kg and timber; (2) Item frequency, fabrication materials, geographical origins, ages and original contents of containers; (3) The distribution of plastic fragments by their presence or absence in 1 m square plots along the transect line. More extensive searches are employed to collect samples of containers for dating. At each site 2-4 observers walk along the foreshore parallel to high water marks for a distance of approximately l km. All containers are examined and suitable specimens collected. The procedure is then repeated in the foredunes of the backshore zone at each site. Two methods of dating containers are employed: relative dating based upon frequent changes in container designs or markings, knowing the period of manufacture of each type; absolute dating from the interpretation of individual date codes marked on containers and showing their dates of manufacture. Methods of identifying container contents, fabrication materials and geographical origins have been discussed in earlier papers.
The Characteristics of Litter on West European Beaches Having developed a system capable of assessing the problems of marine litter on beaches, what signs are there that international measures are required to reduce its impact? The analysis of data collected so far show several features which suggest that marine litter has lost its national identity and joined the multinationals. Several recurrent trends in the composition, ages and distributions of litter have been identified from surveys completed to date. The composition of litter on beaches is diverse; the main constituents being containers of all types and sizes, polythene sheeting, rope, wire, fibreboard, paperboard, light bulbs, fishing gear, out-dated pyrotechnics, packaged hazardous goods and occasionally partly used drugs (Table 1). The mean foreshore density from 150 transects on the beaches of the Cherbourg Peninsula, excluding items over 15 kg, was 27.14 g m -2. The corresponding value for West Jutland beaches was 103 g m-2 for 120 transects. Containers made from plastics, glass, metal and wood accounted for over 80°7o of beach litter samples by weight. Of these, more than 44°7o were plastics, mostly high and low density polyethylene moulded bottles and smaller numbers of polyvinylchloride and polystyrene containers. The original contents of plastic containers collected from sampling sites on a selection of West European beaches are shown in Table 2. Lavatory cleaner and household cleaner 291
Marine Pollution Bulletin
TABLE 1
TABLE 3
Partly used drugs found on a 3 km stretch of beach at Sandwich Bay, Kent, 1978-1979.
The geographical origins of container samples collected from west European beaches (percentage of the identified sample).
Product name Magnacid Pulver *Aspirine U P S A
Drug or type
Country of origin
Magnesium silicate powder/antacid
Netherlands
Acetylsalicylic acid (Aspirin tablets)
France
Sandwich Cherbourg West U.K.National Bay, Kent Peninsula Jutland Survey 1973-1976 August 1978 April 1979 1978-1979 Sample number (n)
989*
1619
2079
6410¢
United Kingdom
28.6
36.3
51.5
71.0
France
24.2
34.7
10.4
10.5
Antibiotic/cortisone (eardrops)
Brazil
Benelux
21.5
8.8
8.3
5.1
Antimalaria tablets
United Kingdom
West Germany
12.6
7.7
8.5
4.4
Deltarhinol
Corticosteroid nose drops
Belgium
Mylanta
Antacid-antiflatulent
USA
Aft-B-Total
Vitamin B Complex tablets Norway
Other European countries (excluding USSR)
Otomicina *Paludrine
10.6
6.6
12.2
5.9
North and South America
1.8
2.8
4.9
1.2
0.4
1.4
1.7
1.0
0.3
1.1
1.7
0.5
Purganol Daguin
Laxative tablets
France
Albyl Setlers
Aspirin tablets
Sweden
Unknown
Sulphadimidine tablets
Netherlands
Asia (including USSR)
Codeine tablets
Netherlands
Oceania
*Calcipen Leo
Penicillin tablets
Scandinavia
Africa
*Pfizers Terramycin
Antibiotic
Unknown
Total
*Kodinfentabletter
Biseririte tablets *Riabal tablets
Antacid tablets
West Germany
Anticholinergic agent
France
Vitamin C tablets
Spain
*Pirocrid
Protizinic acid
France
*Tetrabromethan
Tetrabromathene
West Germany
*Benadryl Capsules
Antihistamine
USA
*J uvapyrin Dolder
Anti-pyretic and analgesic
Switzerland
*Ovran
Oral contraceptive tablets
United Kingdom
Redoxon tablets
*Medium to high hazard rating based on the quantity found and its toxicity if taken orally,
bottles, with capacities ranging from 0.2 to 4.5 I. occupy the first and second rank orders of abundance in each sample. Other containers frequently found include wooden and plastic fish boxes, metal drums of petroleum products, especially marine diesel and lubricating oils, paperboard milk cartons and glass spirits bottles. The original contents of container samples collected from the beaches of the Cherbourg Peninsula and West Jutland were compared statistically. There was no significant difference.
TABLE 2 The original contents of plastic container samples collected from west European beaches (percentage of the total sample). Sandwich Cherbourg West U.K.National Bay, Kent Peninsula Jutland Survey 1973-1976 August 1978 April 1979 1978-1979 Sample number (n)
1134
1378
1259
8381
Lavatory cleanser
30.4
19.5
15.7
11.9
Household cleaners
16.4
14.0
19.1
11.7
Mineral waters
9.4
9.1
5.1
2.2
Dairy products (excluding milk)
3.8
5.1
3.1
7.2
Cosmetics and toiletries
6.8
4.3
3.6
3.1
Milk
4.5
8.5
7.0
3.6
Wine
5.5
7.5
2.3
0.3
Others
16.7
18.8
24.9
9.8
6.5
13.4
19.4
50.5
Unidentified Total
292
100
100
100
100
0 100
0.6 100
0.8 100
0.5 100
*Plastic containers only. l- Plastic and metal containers only.
A comparison of the geographical origins of container samples collected from Cherbourg and West Jutland beaches, shown in Table 3, also showed that there was no significant difference. In each sample there was a global scale of container manufacturing sites, including specimens from Australia, Brazil, Canada, China, Japan, South Africa, USA, USSR, Venezuela and New Zealand. In order to assess the persistence of litter in the marine environment, the ages of container samples fabricated from various materials have been deduced. The criteria for selecting specimen brands for dating include the following: (1) they have been marketed continuously for more than 10 years in disposable (one-journey) packages; (2) they are usually market leaders for each type of product including lavatory cleansers, household cleaners, long life milk and spirits; (3) they are usually marketed in large quantities (8-10 x 106 units per annum) in several countries. Relative dating methods show that more than 85°7o of each of four container samples collected from West European beaches have been current production types. Absolute dating of smaller samples has shown that more than 68°7o are less than 4 years old (Table 4). This would suggest that plastic containers, particularly those made from high density polyethylene, are relatively short lived contaminants of the marine environment, if a dating scale in years is regarded as small. Some trends have been deduced concerning the fate of plastic bottles in the marine environment. Fragmented specimens were found in sample collections on the French and Danish beaches with frequencies of 17.7% and 15.7% respectively. They were more prominent in bottle samples collected from backshore than foreshore locations. Statistical analysis showed that for each study area disproportionately higher frequencies of older plastic containers, those over 4 years, were fragmented. Also these older plastic containers were more prominent in samples collected from backshore rather than foreshore locations.
Volume 12/Number 9/September 1981 TABLE 4 Age of container samples collected from west European beaches (cumulative percentages). Sandwich Bay, Kent 1973-1976
Cherbourg Peninsula August 1978
240*
802
954
0- l
47.5
22.9
24.8
12.2
l- 2
84.2
61.7
63.6
32.0
2- 3
92.1
77.9
78.3
58.1
3 -4
97.9
85.8
84.9
68.6
Sample number (n)
West U.K.National Jutland survey April1979 1978-1979 188
Age (years)
4- 5
100
92.5
89.9
80.4
5 -6
100
94.5
95.0
85.1
6- 7
100
95.5
97.1
87.8
7 --8
100
96.5
97.8
91.6
8 -9
100
97.3
98.5
94.8
9 - 10 10 - 11
100 100
98.5 99.1
98.9 99.5
95.8 97.9
11 - 12
100
99.6
99.6
98.5
12 - 13
100
13 - 14
100
99.8 100
99.8
99.5
100
100
*Sample of 240 polyethylene bottles.
This field evidence suggests that bottles made from the major thermoplastics, especially high density polyethylene, are photodegradable out of water. Photodegradation causes the embrittlement of plastics followed by fragmentation, probably within 2 years of them being discarded in West European waters. If there is an accumulation of plastic bottles, it is of a duration of less than 2 years and takes place beyond the reach of normal wave action in the backshore zones of beaches. Differences in the rates of degradation of plastic, glass and paperboard containers appears to be minimal when the mean ages of samples with individual date codes are compared (Table 5).
TABLE 5 The mean ages of container samples fabricated from different materials. Cherbourg Peninsula August 1978 Glass* Paperboard t Plastics $
2.50 1.07 2.95
ll3 44 645
0.10 0.04 0.09
West Jutland April 1979 2.17 1.17 2.86
108 35 811
0.09 0.06 0.07
~ Mean age in years. n Sample size. ag Standard error of sample mean. * Mostly white flint spirits bottles. t Mainly milk cartons. ~: Mostly high density polyethylene bottles.
Another major concern is the widespread distributions of marine litter, especially plastic fragments, in the areas surveyed. Plastic pieces were found in 94% of transects on the French and Danish beaches, and were generally distributed across both foreshore and backshore zones. In the United Kingdom national survey plastic fragments were reported at 77.8% of the 797 sample sites, compared with frequencies of 34.2% for oil, 62.7O/o for wood (including driftwood) and 84.8% for one or more plastic containers. It has yet to be established whether the plastic fragments originate from photodegraded plastic bottles in situ.
The trends in composition and geographical origin of container samples indicates that the source of discard is ships and pleasurecraft at sea. More direct evidence of this source is frequently available in the form of out-dated pyrotechnics and lifeboat rations, fishing gear, drug containers bearing the names of ships' dispensing chemists and labels on spirits bottles indicating that the contents are to be consumed only by ships' crews. Although holidaymakers contribute to beach litter, this is usually only during the summer months and in locations with easy access by road. The composition of discards originating from this source is characterized by a high proportion of metal drinks containers, especially metallic with ring pull tops. These are generally evenly distributed across foreshore and backshore zones of beaches.
Marine Litter Controls At the moment there are few, if any, effective means of controlling or preventing litter dumping. In some parts of the world marine litter levels have been high enough to warrant beach cleaning operations. The extent of such remedial action and the costs incurred have yet to be determined. In parts of the Eastern Mediterranean ground nut harvesters have been adapted for use as beach cleaners. Elsewhere, larger purpose-built machines have been developed, the latest weighing 23 tonnes and capable of cleaning up to 2 hectares of shore an hour. Usually, to justify expenditure, only the most popular bathing beaches are cleaned regularly during the summer season. Hence beach cleaning is unlikely to have any significant effect upon the present levels or distributions of marine litter. A more worrying aspect of litter appearing on beaches was illustrated recently in southern England where local authorities are having to collect and safely dispose of a variety of packaged hazardous chemicals which are now regularly washed ashore. Clearance operations on the Isle of Wight have cost up to £8000 per annum. This expenditure has not been recovered in accordance with the "polluter pays" principle because, in most cases, package labels have been lost and consequently the owners or shippers of the materials cannot be identified. Other issues, concerning compensation and liability arrangements following beach pollution by packaged hazardous goods lost from ships at sea, have been discussed in earlier papers. The available evidence suggests preventative measures are the only effective means of controlling litter in both terrestrial and marine environments. As packaging is a major constituent of litter, changes in the types and uses of packaging have been proposed and in some cases implemented. But on a small scale one approach has been to limit or even prohibit the use of certain types of disposable packaging. For example, in Denmark the uses of metal beverage containers are already restricted and they will not be used for the home market from 1982. Plastics materials, which are the major constituent of packaging and hence litter, have been developed with enhanced degradability. The three major thermoplastics packaging materials can be made to degrade faster on exposure to ultra-violet light. This has been accomplished by compounding existing components with photosensitive additives or by the incorporation of minor amounts of 293
Marine Pollution Bulletin
comonomers containing photosensitive groups. It has been established that a bottle made from one of these materials will degrade to a fragmentable condition within 3 months compared with 3 years for its unmodified counterpart. If plastics with enhanced degradability are used extensively for packaging, they may well reduce the persistence of these materials in the marine environment but any benefits could well be offset by increases in the quantities used and therefore disposed of at sea. The evidence available suggests that enhanced degradability plastics would not be a commercial success because: (1) They prevent the re-use of packaging materials by encouraging further development of disposable ones; (2) There are technical problems in ensuring that degradation will not occur during the required life of the new materials; (3) It remains to be established whether new materials prevent any toxic or tainting hazards during use, particularly when used in food packaging, or ecological hazards after disposal; (4) The new materials are expected to cost more than their unmodified counterparts, and this may well reduce their commercial and social acceptance. All of these arguments are contested by the manufacturers of rapidly degrading plastics. Akerlund & Hausing of Sweden, the manufacturers of "Ende-plast", which degrades by natural photochemical, thermal and microbiological action when exposed to ultra-violet radiation, claim that the additives are harmless to mankind and the environment, as also are the end products of degradation, so that no adverse reaction of any kind may be expected from their use. With increased raw material costs the makers of conventional plastics are pursuing various ideas to conserve raw materials. If these ideas are implemented the environmental impacts of plastic materials could well be reduced at a point higher up the chain than the main culprit, the consumer. A new approach by plastic manufacturers includes: (l) Reducing container weights by using a foam structure; (2) Incorporating suitable extenders which are cheaper than base polymers; (3) Reducing container wall thicknesses; (4) Using multi-layer structures of various plastics materials; (5) Using biaxial orientation of the base polymer such as polyethylene terephthalate (PET) which is presently used for carbonated beverage containers. Failing these moves, which would presumably be financially controlled, a more direct preventative approach is to reduce or eliminate inputs of litter into the marine environment from ships. At the present time the routine disposal of shipboard-generated solid wastes at sea does not constitute an offence under IMCO Conventions in force. However, Annexe V of the 1973 MARPOL Convention, as amended by the 1978 Protocol, does contain provisions regarding the disposal of shipboardgenerated garbage and the prevention of this type of pollution. These provisions state: (1) The disposal of plastics materials anywhere at sea is prohibited; (2) The disposal of other garbage including paper products, glass, metal and bottles is to be more than 12 294
nautical miles from the nearest land, unless passed through a comminuter or grinder, and 25 nautical miles for dunnage, lining and packing materials which will float; (3) Governments that are Parties to the Convention are urged to take appropriate action to ensure the enforcement of the provisions, as early as possible, by providing adequate facilities for the reception of garbage from ships. Unfortunately the effectiveness of these proposals in real terms is questionable. Firstly, Annexe V of the MARPOL Convention is optional and not an obligatory annexe and therefore this intentional distinction may well delay the implementation of the regulations contained in it. Secondly, economic, technical and legal difficulties have been reported which will affect the implementation of the proposals; for example, the types of solid waste storage or disposal systems used by ships on long haul routes. Systems have not yet been developed which can process shipboard-generated solid wastes to the point of zero discharge of waste into the sea. In particular the segregation and disposal of plastics materials is expected to be a major difficulty within the constraints of available time and space. Problems have also been reported with the use of compactors to store wastes, primarily poor reliability and unsatisfactory sanitary standards. Thirdly, it has yet to be established whether ports can provide the necessary facilities for disposal ashore of shipboardgenerated solid wastes. Some ports and even states still insist that ships' garbage is disposed of at sea as a public health measure. Fourthly, it will be difficult, if not impossible, to enforce the regulations governing the disposal of wastes at sea. Lastly, the economic implications regarding the construction of reception facilities, the equipment requirements of existing ships and the training of personnel have yet to be fully explored. Despite these apparently intractable problems some progress has been made on short sea routes following the introduction of voluntary codes of practice. The large United Kingdom ferry operators Sealink (UK) and Townsend-Thoresen now store most shipboard-generated solid wastes, other than food wastes, in compactors for disposal ashore. The equipment used has met the required operating standards and has proved to be very reliable. With regard to hazardous wastes the United Kingdom's Department of Trade has recognized the dangers and serious consequences of pyrotechnics if they are found and improperly handled by members of the public, especially children. Consequently, in a notice to mariners (Merchant Shipping Notice - M 787, November 1976, Disposal of outof-date pyrotechnics) guidelines have been laid down for the correct disposal of these items from UK registered ships. Another recommendation urges Masters and Shipowners to report incidents involving losses of packaged hazardous goods at sea (Merchant Shipping Notice M 953. Reports on incidents involving packaged dangerous goods). This is in addition to the existing IMCO Cargo Loss Reporting Scheme which has proved inadequate as an early warning system to prevent beach pollution by these materials. This recommendation was due largely to recent incidents involving packaged hazardous chemicals washed ashore onto the beaches of southern England following losses from ships at sea. Unilateral actions of this type by the United
Volume12/Number9/September 1981 Kingdom will have limited success because it can only apply to 10-15 % of coastal traffic around the British Isles. In the absence of any effective marine litter controls at the present time and probably during much of the next decade, litter abatement agencies and environmental pressure groups are initiating campaigns to try and correct the situation. In the United Kingdom the Keep Britain Tidy
Group is promoting voluntary codes of practice, which apply to all seacraft, which seek to eliminate the disposal of litter at sea. More research will be undertaken to assess the environmental impacts of marine litter and establish a quantitative basis for a comprehensive surveillance system. The pollutants change with progress but the proximate cause is unaltered.
Marine Pollution Bulletin, Vol. 12, No. 9, pp. 295-301, 1981 Printed in Great Brilain
0025 - 326X / 81/090295--07 $02.00/0 © 1981 Pergamon Press Ltd.
Present State of Oil Pollution in the Northern Indian Ocean R. SEN GUPTA and TARIQ W. KUREISHY National Institute o f Oceanography, Dona Paula, Goa 403004, India
A consolidated picture of oil pollution for the northern Indian Ocean is presented. Oil slicks were sighted on 5582 observations, about 83.5% of the total observations of 6689. The range of concentrations, of the floating tar balls, is 0-6.0 mg/m 2 in the Arabian Sea. Similarly, the oil tanker route in the Bay of Bengal has the range of 0-69.75 mg/m 2. North of this route, the Bay of Bengal is comparatively free from this floating tar. Mean concentrations of dissolved and dispersed hydrocarbons for 0-20 m are 32.5 and 24.1 ~g kg -t, respectively, in the Arabian Sea and the Bay of Bengal.
Since the initiation of Marine Pollution (Petroleum) Monitoring Pilot Project (MAPMOPP) of the Integrated Global Ocean Station System (IGOSS), several reports on the progress of the project and the state of oil pollution in different ocean areas of the world have been published (Sleeter et al., 1974, 1976; Levy & Walton, 1976; Wong et al., 1976; Levy, 1979, 1980; Suzuoki & Shirakawa, 1979; Sano et al., 1979; Shigehara et al., 1979; Gerard, 1979; Kohnke, 1980; Sobchenko et al., 1980; Oostdam, 1980). Most of these reports analysed the data collected from specific areas. Only two reports (Kohnke, 1980; Levy, 1980) cover all the oceanic areas and include the data collected by all the participating countries on the three MAPMOPP parameters, i.e. visual observations of oil slicks and other floating pollutants, particulate petroleum residues (tar balls), and dissolved and dispersed hydrocarbons. Data from a few series of observations from the Arabian Sea and the Bay of Bengal, mainly from the two oil tanker routes across them, have been published recently (Sen Gupta et al., 1978, 1980; Qasim & Sen Gupta, 1980; Fondekar et al., 1980). These reports have mainly dealt with the dissolved
and dispersed hydrocarbons and no attempt has been made so far to present a consolidated picture of oil pollution, covering all the MAPMOPP parameters, in the Indian Ocean incorporating the data collected by all the participating countries in the region. This report is an attempt to present an analysis of the data collected from the Indian Ocean during MAPMOPP. Since the data available with the Japan Oceanographic Data Centre, which was nominated as Responsible National Oceanographic Data Centre (RNODC) for the Indian Ocean region by IGOSS, covered only the area north of the equator (Fig. 1), this report is entitled 'Present State of Oil Pollution in the northern Indian Ocean". Data on all the three MAPMOPP parameters, collected from this area up to June 1980, are analysed in detail in this report. The areas covered are 00-30 ° N and 50°-100 ° E for oil slicks and 5 °20 ° N amd 69 °-99 ° E for floating tar and dissolved/dispersed hydrocarbons. The fourth MAPMOPP parameter, beach tar, is not included in this report since these results have been published earlier (Dhargalkar etal., 1977). India, Thailand and Malaysia are the three countries most actively participating in this project in the Indian Ocean region. While India has submitted to Japan RNODC data on all the three parameters from 1977 onwards, Thailand has submitted data on dissolved and dispersed hydrocarbons from 1978 and Malaysia data on oil slicks and other floating pollutants from 1979. However, the number of participating countries from the region is gradually increasing. A total of 6689 observations of oil slicks and other floating pollutants, collected by ships from the participating countries in the region and by many other merchant ships participating in the 'Ships of Opportunity' programme of 295