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Previously, the resources of the North Sea could be used with very little conflict arising among resource users. With increased populations, growth in industrial activity, and vastly expanded technical capability, these resources are nearly overly exploited and are also, in management terms, in conflict with one another.
The fisheries of the North Sea, for example, have visibly declined, and the amount and nature of the wastes that are finding their way into the sea are causing concern regarding possible long-term impacts on food-chains, ecology, and overall human well-being. Waste and pollution enter the North Sea through several pathways.
An element of overfishing is almost an inevitable consequence of a commons resource, where regulation of access tends to await a demonstrable decline in stocks and where international regimes have influence by virtue of the necessity to guarantee fair play. The future of North Sea commercial fish stocks, notably the demanded species of white fish, is problematic, with signs pointing to a contracting industry, higher prices, and only very slow recovery. Either the fish market will have to shift to unpopular species or the industry will have to restructure to a relatively small number of licensed boats, or both. Currently, the Common Fisheries Policy is still in a state of flux, with the politicians erring on the side of optimism and the fisheries biologists leaning towards caution.
There is no prospect of any immediate solution to this dilemma, although the European Union does at least control its own member states, namely Germany, the Netherlands, France, Denmark, Belgium, and the United Kingdom. Norway and Sweden are not yet members of the Union (though both may apply within this decade) and operate through the North East Atlantic Fisheries Commission along with their European Union partners. This is a less satisfactory forum from the viewpoint of sound science and well-adjusted management, but at least it provides a common negotiating arena. The main difficulty lies in rationalizing the industry in those areas in which fishing is still very much part of the local economy and culture - in Scotland, north-east England, and southern Norway. Inevitably, these historic fishing regions will slowly decline - as have other now-exhausted extractive industries - with a slow reorganization of the local economy towards other activities, helped by redundancy payments, job retraining, and the general mobility of job opportunities in the modern post-industrial society.
Pollution of the North Sea
Significant environmental attention is currently being devoted to the pollution of the North Sea. Even though this pollution has less demonstrable impact than the decline of a once-profitable fishing industry, it is a feature of the contemporary environmental scene that harm to food-chains and ecological systems generally now receives weighting equal to damage to human life and property. This is not to say that the modern environmentalist is callous; merely that ecological indicators of natural health are nowadays taken seriously and are protected in law. It is of some significance that the definition of environmental "harm" in European law generally extends to the viability of non-human life-forms.
The most significant areas for concern regarding pollution are the dumping of sewage sludge at sea, the incineration of toxic wastes in the open sea, the discharge of toxic and eutrophic substances in waterways leading to the North Sea, and the deposition of both toxic and eutrophic pollutants from both dry and wet precipitation in the open atmosphere.
The Dutch MANS project is currently attempting to gather a complete picture of the total contribution of pollutants entering the North Sea. This task was initiated by the North Sea Conference in the mid-1980s, but it is still a long way from completion. Indeed, much original research is still being conducted on the pathways of pollution flows, especially in the open North Sea. The regional research of the North Sea Task Force is also contributing to the level of knowledge about the open sea.
An important difference of opinion divides the basin states as to the grounds for controlling pollution in a vast commons such as the North Sea. The British, and to some extent the French, tend to rely on scientific research and estimates of the capacity of ecosystems to assimilate pollutants. Assimilative capacity has two main interpretations, namely rendering harmless by decomposition or rendering harmless by dispersal and dilution. The British line is to try to develop detailed proper scientific audits, estimate rates of assimilation, and take action where likely benefits are offset by predicted costs. This can be a recipe for postponement and may result in unnecessary damage on the basis of insufficient knowledge. It is also a position that invites delaying action by vested interests. Nevertheless, it may also be seen as a pathway to least-cost management.
However, this is not a popular position any more. The continental approach favoured by the Germans, the Danes, and the Dutch is that of precaution, taking preventive action ahead of scientific certainty on the grounds of its being better to be safe than sorry. This approach is based more on moral principles of ecological integrity rather than on strict cost-benefit principles. But it is finding favour because it reflects the mood of the modern age, most notably where toxic, persistent, and bio-accumulative substances are concerned. As such, it has now become the dominant approach to North Sea management, though the scientific mode still has its strong supporters. Despite what is discussed below, as far as toxic substances are concerned, North Sea basin states, including the United Kingdom, are committed to the principle of precaution. In practice there is nothing but advantage in trying to combine the two approaches, hence the growth in scientific audits, predictive models, and cost-benefit analyses.
It is interesting to record the shift in position between Britain and its European Union partners over the matter of environmental objectives, based on assimilative capacity and fixed emission standards, linked to fair competition and harmonious application of regulation. At the heart of this dispute lies the distinction between what the British like to regard as environmentally sensitive cost-benefit analyses, in which the consequences of pollution reduction are set against societal gains, and command-and-control regulation, which is increasingly being tied to best-available technology (or techniques). In practice, however, Britain does not use a cost-benefit approach at all seriously. The point is political and rhetorical, designed to sharpen debate and to maintain an important sense of perspective on the role of science in environmental policy-making.
The continentals are apparently less concerned over the possible severe costs of implementing directives aimed at reducing pollution at source. The British like to weigh different options in relation to least overall cost. The precautionary principle is very much the middle course. Eventually some combination of all three approaches is likely to prove the most workable. Meanwhile, the cost-benefit approach to setting emission controls is only slowly becoming recognized (Boehmer-Christiansen 1990).
Behind this argument between science and precaution are important political nuances. In Germany, Denmark, and the Netherlands, the composition of national parliaments is notably more "green" than in Britain and France. The view taken by these "greener" parliaments favours equal treatment: namely, if their country is being forced to clean up expensively, then all countries sharing a common resource should do the same. To begin with, attention was on the obvious "soft" targets of oil and gas production platforms. But they apply only to the United Kingdom and Norway.
In the Netherlands, considerable public alarm attends the decline of fish and mammal species in the North Sea, and general concern prevails over the increase in nutrients from sewage works and agricultural activity. The growth in algal blooms is seen as a consequence of all this, whereas in the United Kingdom the scientific evidence is interpreted much more narrowly. Most blooms are regarded as the consequences of historical fluctuations in growth and productivity, as well as of fluctuations in sunlight, temperature, and the movement of nutrient-rich currents from the north-east Atlantic. The British position is that only a small and localized amount of nutrient build-up, mostly in the shallow seas around Denmark and southern Sweden, is serious.
Just as significant here is the role of the scientist and the scientific model. In some continental countries, scientists tend to be closer to the political centre on account of governmental funding patterns and advisory positions. More important, perhaps, regulations tend to be fairly formal, based on scientific evidence. In the United Kingdom especially, scientists are featured as more independent and are seen as the source of cautious advice. However, the UK government has a policy of acquiring both official and non-official scientific advisers whose role can be very influential. Scientific models are now popular everywhere, but the Dutch build impressive computerized edifices on limited data, unlike the British who tend to build models as the scientific evidence evolves. The result is a tension between the role of science and predictive models in the management of the resource. For toxic substances, and for incineration issues, consensus favours precaution. For nutrients, and to a lesser extent ocean disposal of industrial wastes, far greater divergence prevails.
It is now estimated that as much as half of all the toxic wastes discharged into the North Sea comes from the atmosphere in the form of aerosols falling as dry matter or precipitated as rain. This has been discovered only over the past 20 years as a result of new monitoring and recording techniques.
It is important to exercise some degree of caution about the accuracy of these values since they are often based on extrapolation and estimation. Usually maximum and minimum values are expressed to give a general idea (table 8.7). Estimates are obtained mainly from measurements of wet deposition and air concentration at coastal stations, although this varies according to which text is consulted. Table 8.7 shows quantities of atmospheric pollutants in the North Sea as submitted for the International North Sea Conference in 1990.
Several recent attempts have calculated atmospheric inputs into the North Sea by means of atmospheric transport models (van Aalst, Duyzer, and Veldt 1983; van Jaarsveld, van Aalst, and Onderdelinden 1986). The models calculate annually or seasonally averaged concentrations and depositions from emissions and meteorological data. However, windspeed, atmospheric stability, mixing-layer depth, and precipitation at sea generally differ from those of the surrounding land (Höhn 1973; Joffre 1985; RSU 1980) and from the different types of water masses in the North Sea (Sibthorp 1975). This will inevitably introduce errors additional to the uncertainty of factors such as accurate emission values.
Deposition maps calculated by van Jaarsveld, van Aalst, and Onderdelinden (1986) show a strong north-south gradient in depositional flux and indicate that measurements taken at coastal stations in the Netherlands, Belgium, and the United Kingdom are likely to be higher by a factor of 2-4 than the average flux into the North Sea. Adjusting for the differences, the measured values are comparable with the modelled values.
Knowledge is limited, however, owing to the lack of:
1. adequate and representative measuring data of concentrations in air and precipitation;
2. insight into and quantitative parameters for dry deposition of gases and particles over the sea; 3. accurate data on all European emissions.
Table 8.8 shows the relative contribution of heavy metals from the North Sea states by atmospheric deposition, revealing that the United Kingdom contributes the greatest quantity. The amounts of nitrogen entering the North Sea via the atmosphere from various countries is shown in table 8.9.
Table 8.7 Atmospheric pollution in the North Sea (tonnes)
|Estimates based on 1988 deposition measurements:b|
|Estimates based on emission values for various years (1982-1986):b|
Source: IQSR (1990).
a No information is available on phosphorus, mercury, chromium, nickel, arsenic, hexachlorohexane, or polychlorinated biphenyls.
b. Minimum and maximum estimates result from different calculation methods, calculated for an area of 525,000 km² north of the Straits of Dover.
Considerable quantities of naturally occurring radionuclides, such as potassium 40, rubidium 87, uranium, radium, and nuclides of the decayed series of uranium and thorium, exist in sea water and other environments. As a result of the human utilization of the nuclear fission process, so-called artificial or man-made radionuclides are to be found in measurable quantities in sea water.
Table 8.8 Calculated relative contribution of some countries to the total deposition in the North Sea (%)
Source: Adapted from van Aalst (1988, 280).
a. Pre-unification West Germany.
Table 8.9 Nitrogen (reduced and oxidized) entering the North Sea by air, 1988 ('000 tonnes)
|Country of source||Amount|
Source: Rose (1990, 75).
The principal sources of radionuclide discharge have changed over the past 30 years. Major inputs initially originated via the fallout from nuclear bomb testing in the 1960s, then from the emergence of nuclear power stations and nuclear fuel reprocessing plants during the 1970s, and recently from the accident at Chernobyl in 1986. Other sources, such as the use of radioisotopes in hospitals, science, and industry, contribute relatively small amounts. Since the North Sea is geographically far removed from the major testing sites of the atomic bomb explosions that took place in the Pacific islands in the 1960s, radionuclides from these sources caused only a slight increase in background radiation in the basin states. In the second half of the 1960s, after the practical cessation of atmospheric atomic bomb tests, the introduction of radionuclides from fallout was still only slight and the activity concentrations of those substances decreased markedly in the North Sea (Kautsky 1988, 391).
In 1970 in the southern North Sea and in 1971 in the north-western North Sea, an increase in caesium-137 concentrations was observed (Kautsky 1988). After thorough investigations, it became clear that they had originated from the nuclear fuel reprocessing plants at Sella-field in Cumbria and at Cap la Hague in France. The Sellafield plant was emitting into the Irish Sea waste that followed the oceanic currents and entered the northern North Sea, whereas the French installation was discharging into the English Channel and hence into the southern North Sea. Since this time, a reduction in the concentrations of caesium-134 and caesium-137 from the Sellafield works has been attributed to the installation of the SIXEP (Site Ion Exchange Effluent Plant), which treats water contaminated with radioactive waste from various irradiated fuel storage ponds and other related facilities (BNF 1985).
The most recent large addition of radioactivity to the North Sea came from the disaster at Chernobyl in May 1986. Clouds of radioactive material travelled across the North Sea and also contaminated some areas of the British uplands. As a result, caesium-137 values of 100205 Bq per m³ were measured in the German Bight and along the coast of Jutland, Denmark (Becker 1987). Owing to the constant water-exchange process, however, the radionuclides that entered North Sea waters via fallout have in the meantime largely been transported away. Caesium-134 and caesium-137 occur largely in soluble form. Loss of caesium-137 from the sea water by absorption into particulate matter or bottom sediments is, therefore, expected to be in the low range of no more than around 5-10 per cent.
Table 8.10 Estimated annual inputs of petroleum hydrocarbons to the North Sea, 1980 and 1986 ('000 tonnes)
|Accidental shipping losses||15||5-12|
|Dumped sewage sludge||5||Not included|
|Dredge spoils||2.8||Not included|
|Natural seeps||Not included||0.3-0.8|
|Other coastal industrial effluents||Not included||9|
Sources: Read and Blackman (1980); Bedborough and Blackman (1986); Dicks, Bakke, and Dixon (1988), 525.
The recent oil exploration and production now under way in the North Sea have inevitably introduced oil into the marine environment. Oil is extracted, shipped throughout the North Sea, and refined at many coastal locations, increasing the risk of spills from these installations as well as from offshore fields. Other sources of oil entering the North Sea and the amounts of petroleum hydrocarbon contained within them are listed in table 8.10, which provides data for 1980 and 1986. During that period, accidental losses decreased by a factor of 2 and offshore activities increased oil-spills by a factor of 10. These statistics are disputed by Greenpeace (Rose 1990), which claims that 72 per cent of oil pollution from shipping is due to deliberate discharges.
The Interim Quality Status Report (IQSR 1990) estimates that illegal oil discharges were between 1,100 and 60,000 tonnes and legal discharges between 1,000 and 1,500 tonnes. States signatory to the Paris Convention have set a limit for oil discharges from oil rigs and other exploration structures of 40 mg oil per litre of sea water. The United Kingdom is well above the other countries in this respect, although it is unclear whether it is exceeding the limit.
The oil-slick resulting from the Gulf conflict in 1991, described by many environmentalists as one of the world's worst ecological disasters, illustrates the great risk that similar oil-spills and accidents could create similar environmental destruction, albeit on a smaller scale, in the North Sea. Except perhaps for the Ekofisk Bravo blow-out in 1977, which spilled 15,000-22,000 tonnes of oil over seven days (Grahl-Nielsen 1978), the North Sea enjoyed a long period free of massive oil-slicks, although many smaller spills have occurred. In January 1993 a supertanker carrying about 25 million gallons of crude oil ran aground off the southern tip of the Shetland Isles (INER 1993a). The incident prompted environment and transport ministers to step up ongoing efforts to produce "a common policy on safe seas" (INER 1993b, 37).
On the basis of information provided by North Sea states, there are no clear or significant trends in observed slicks that can be detected in the North Sea area since the 1987 Conference (IQSR 1990). Annual surveys show that the United Kingdom achieved a 44 per cent reduction in the number of oil pollution incidents between 1980 and 1987. With regard to other North Sea states, Denmark shows no clear trends, whereas reports for the Netherlands indicate no significant changes in the pattern of oil-slicks during 1986-1988. For the German Bight, results of airborne surveillance operations show a decrease in oil pollution in terms of area covered and quantities involved. The Swedish Coast Guard reports that, compared with 1987, 1988 showed a 49 per cent increase in oil pollution on the west coast of the country. In Norway, the number of recorded oil pollution incidents increased, but the increase was attributed to the introduction of new reporting routines for spills smaller than 1 cubic metre (i.e. they all require notification) and the extended reporting of spills by local authorities and private persons (IQSR 1990).
There was no consensus among North Sea states on estimations of accidental oil discharges from ships, and no information has become available to improve the estimations presented in the 1987 QSR.
Direct inputs and river inputs
Direct inputs are those discharges that come straight into the North Sea, usually via a large effluent transport pipe. These discharges may include concentrations of, for example, heavy metals, nutrients, and organohalogens. The chemicals are discharged into the North Sea from rivers and by direct dumping. The quantities involved are examined below.
The 1987 Quality Status Report gave estimates of inputs from these sources over the years 1984, 1985, and 1986. It is surmised that, of the 400,000 million litres per day of water flowing into the North Sea, 80 per cent is accounted for.
Statistics for the total riverine inputs into the North Sea are somewhat unreliable. This is because not all rivers are included in the assessments, there are no estimates of data reliability, and the French rivers do not discharge directly into the North Sea (but into the Dover Straits).
Data for direct inputs are more diverse and more incomplete than those for rivers. In general, there seems to be an increase in most of the substances in the update of the figures presented at the third international conference in the Interim QSR (IQSR 1990) (see table 8.11).
The major exporters of substances via this route are West Germany, the Netherlands, and the United Kingdom. This is obviously due to several factors, including the geographical position of the rivers, the extent of industrialization on the banks of the rivers, and the countries through which the rivers and their tributaries pass. The IQSR made no estimation of the eastern European contribution.
Disposal of industrial wastes
Direct disposal of industrial waste is now largely controlled through international agreement. In the mid-1980s, West Germany was the principal discharger of such wastes (table 8.12). The largest and most important source was titanium dioxide emanating from both Belgium and West Germany. By the late 1980s, a reduction of 43 per cent had occurred in total industrial wastes discharged into the North Sea, with a corresponding reduction in the disposal of heavy metals (e.g. from 40 per cent for cadmium, 60 per cent for copper, to the nearly total removal of arsenic).
The United Kingdom remains the only North Sea basin state to dispose of solid industrial waste, most of which is associated with coastal coal workings and with fly ash from power-station residues. Despite the agreement of the 1987 North Sea Conference to end all disposal of industrial waste by 1990 (except for materials of natural origin or those that can be shown to produce no environmental harm), Britain continues to dump colliery waste on the grounds that it is an inert material. It is only a matter of time before Britain will be forced to abandon this practice and to come in line with the rest.
Table 8.11 Direct river inputs to the North Sea (tonnes)
|Belgium 1988||Denmark 1986||FRG 1988||Netherlands 1988||Norway 1988||Sweden 1988||UK 1986||Total|
|Cadmium||4.1||0.4||14||26||0.2||0.3||< 28||< 73|
|Mercury||1.8||0.2||16||6.6||0.2||0.02||< 7.9||< 33|
|Lead||62||4.3||250||330||17.3||9.5||< 320||< 994|
|Zinc||495||44||3,000||3,900||337||210||< 2,300||< 10,290|
|Hexachlorohexane||0.1||-a||0.7||1.4||-a||-a||< 0.4||< 2.6|
|Polychlorinated biphenyls||0.05||-a||< 0.2||0.2||0.09||0.09||-a||< 0.6|
Source: lQSR (1990, 216).
a. No information.
Table 8.12 Disposal of liquid industrial wastes into the North Sea (tonnes)
|Country of source||Amount dumped||Year||Cadmium||Mercury||Copper||Lead||Zinc||Chromium||Nickel||Arsenic|
Source: IQSR (1990, 152).
Again, this matter highlights the difference of opinion between UK and continental practice over the appropriate means of protecting the North Sea.
Disposal of dredged materials
Shipping demands minimal water action or currents within harbour basins and therefore creates the optimal conditions for the sedimentation of river- or seaborne materials. It follows that it is necessary to maintain ports and channels in order to keep them accessible to (marine) shipping. Such material is removed by dredging (van Driel, Kerdijk, and Salomons 1984), which also takes place during the construction of new harbours/ports or extensions to existing ones.
A 1979 survey (Förstner and Salomons 1988) based on responses from 37 countries showed that around 350 million tonnes of maintenance dredging occurred that year. It was estimated that approximately 230 million tonnes of this comprised the average annual quantity of dredged materials. The survey showed also that dredged material was disposed of via a marine route, being deposited on wetlands and near-shore areas (Förstner and Salomons 1988).
Of the countries surrounding the North Sea, it is Belgium that dumps the largest proportion of dredged materials into the sea (IQSR 1990). There is concern that the dumping of dredged materials is yet another pathway for pollutants to enter the marine environment. The sediments being removed may well contain large amounts of heavy metals and PCBs, and records document an increase in the cadmium concentrations dredged from the mouth of the Rhine since 1920.
Suspended matter originates from the weathering and erosion of soils and rocks as well as from anthropogenic sources and consists of a variety of compounds (e.g. clay minerals, carbonates, quartzes, feldspars, and organic solids). These are usually coated with either hydrous manganese, iron oxides, or organic substances. The coating affects the interaction process between solids and dissolved components. Depending on the external and internal conditions of the sedimentary environment, the redistribution of trace metals, nutrients, and organic components takes place during the formation of the resulting sediments. Dredging is essentially a relocation of seabed materials, and the amount dumped varies annually owing to hydrological conditions, capital dredging programmes, and maintenance dredging schemes.
It is difficult to draw definite conclusions regarding the extent of contamination, and it is impossible to quantify the impact of dredged material. The amount of contamination released into the marine environment is unknown and depends on a variety of factors, such as local chemical conditions.
Certain dumping operations constitute not an increase in the contaminant load to the marine environment, only a relocation of substances. The IQSR (1990) concludes that dredging as such does not significantly increase the pollutant transport to the North Sea, as, even without dredging and harbour construction, the pollutant load would reach the sea eventually. The environmental impact of dumping dredged materials is difficult to assess as the most problematic constituents tend not to stay in the vicinity of the dumpsite.
In future years, contaminated dredged spoils may show a decrease owing to a relative reduction in the pollution of the North Sea, its rivers, and estuaries. A more systematic monitoring programme, however, is still required to identify the pathways of such pollutants and their environmental consequences.
Disposal of sewage sludge
Until an effective sanitary and sewer system was established, sewage was a menace to public health and unacceptable from an aesthetic point of view. The large, integrated sewage treatment works that we have today are the outcome.
The problems of sewage sludge disposal, however, have become pressing since the nineteenth century when liquid industrial waste was diverted into domestic sewers. Although this allowed the degradation of many substances, it has also added another route by which toxic contaminants can enter established disposal routes.
The choice of a disposal route for sewage sludge varies for each North Sea state (table 8.13) but is related to environmental, social, and economic costs. In densely populated areas, which account for many of the North Sea states, and especially those in the southern North Sea area, marine dumping or incineration is favoured owing to obvious land constraints. The lack of access to relatively short coastlines and sensitive littoral ecologies (e.g. the Waddensea in the Netherlands, West Germany, and Denmark) limits marine disposal in most countries (Parker 1988). Countries such as the Netherlands and the United Kingdom have dense coastal populations, and, in the case of the United Kingdom, disposal sites are located approximately 5-10 miles offshore, situated adjacent to major coastal towns, which explains why this route is favoured (Cotter 1988).
Table 8.13 Sewage sludge disposal in countries bordering the North Sea and m some other Oslo Convention signatory states
|Country||Sludge production ('000 tonnes/ year)||Disposal routes (% of total)||Population density (nos/ha)a||Land usage indexb||Length of coastline (km)||Coastline per unit land area ('000)|
|Agriculture||Sanitary landfill||Incineraion||Pipeline to sea||Dumped at sea||Unspecified|
|Countries bordering the North Sea|
|Other OSCOM countries:|
Sources: Parker (1988, 249); note that Parker cites three
additional sources: for sludge production and disposal routes,
Vincent and Critchely (1982); for land area, Whitaker's almanac
(1986); for length of coastline, US Department of State (1969).
a. Population divided by total land area (exclusive of offshore islands and large lakes); this ignores differences in habitability or usage of land.
b. The "land usage index" is derived from (total sludge production x percentage diverted to agriculture and tipping) divided by total land areas (units of tonnes/hectare/year). This provides a very crude measure of the significance of land disposal in terms of usage of land area, ignoring variations in suitability of land for agriculture or tipping. Norway is badly treated by this index because of its very high proportion of mountainous land, but, in association with the population density figures, the index provides a guide to the constraints in other countries.
c. Excluding islands.
d. Of which c. 350 km on the North Sea.
e. Of which c. 400 km on the North Sea.
f. Of which c. 1,600 km on the English Channel/Atlantic.
g. Of which c. 900 km on the Atlantic.
h. All in the Kattegat/Baltic.
Options for the use of sewage sludge as a fertilizer on the land are often impractical owing to the extensive urban areas that may have to be traversed in order to reach agricultural areas. Furthermore, sludge is prone to contamination by toxic residues that render most of it (legally) harmful and thus unacceptable for use as fertilizer. Indeed, the growing prominence of heavy metals in domestic refuse means that the sludge of even small, rural catchments is often not usable as fertilizer. In addition, sewage sludge, if processed incorrectly, smells. The odour is likely to be unacceptable both to local residents and to the public at large. Therefore, where appropriate, disposal at sea is a preferred option, since it involves a single sea trip from a jetty adjoining the works to the dumping site.
Around one-third of the sewage sludge arising in the United Kingdom after treatment is disposed to the sea by ship. The amount dumped in 1987 was around 5,077,000 tonnes, a slight increase as compared with 1985 (QSR 1987). The United Kingdom is the only remaining North Sea country that dumps sewage sludge from vessels into the North Sea. West Germany ceased this practice in 1981 on the grounds that it was damaging the sensitive ecology of the German Bight.
When sewage is dumped into the sea, it usually contains 3-5 per cent solids, a "black milk" that is easily pumpable and readily dispersed at sea. The rationale behind marine dumping is that, because sludge contains primarily organic matter, natural processes will break it down and oxidize it. The same reasoning provides justification for some discharging of raw sewage via outfall pipes running into the North Sea. Sewage sludge contains less than 10 per cent of the toxic materials load currently entering the North Sea and only about 1 per cent of all the heavy metal pollution. Removal of this waste stream cannot scientifically be justified on "narrow" environmental grounds (though it may be on ethical grounds and upon some variant of precaution).
All the same, the 1990 North Sea Conference moved to ban all North Sea sewage sludge dumping by 1998. This example reflects the failure of the assimilative approach to cost-benefit calculation as compared with equal, country-by-country treatment. Politics and a collective inclination to buttress a new morality aimed at protecting the North Sea on precautionary grounds have prevailed. It is highly doubtful that the sludge decision can be justified in terms of economics or natural science, but it may well force a reconsideration of the separation of waste at source and promote the cause of clean technologies.
After putting up a struggle on the basis that the scientific evidence did not warrant such action, the British government reluctantly yielded in order to maintain good relations with its North Sea neighbours. Currently, all sludge-dumping licences are being reviewed with the prospect of early termination. The need to repatriate this sludge has highlighted the dilemma of contamination. About one-half of the total is not disposable on land because it contains a sufficient quantity of residues to be classified as controlled waste and, hence, disposable only at approved sites.
The preferred option for the larger sewage treatment works, such as London, is incineration. This involves no third party for eventual disposal, the technology is deemed satisfactory, and the in-plant production of energy reduces overall costs. The trouble is that local residents are generally of the "Not-In-My-Back-Yard" (NIMBY) disposition and do not want incinerators - regarded nowadays as having a stigma effect similar to that of radioactive waste disposal - in the* midst. This means that any proposal for an incinerator is likely to provoke fierce opposition in the form of a local planning inquiry.
At the heart of this dilemma are two issues. One is the need for a proper environmental audit of disposal options, covering comparative risks, energy requirements, and nutrient flows and toxic residues that are genuinely not recyclable, even with the most advanced processes and technology. The other is the application of price-control regulations to force industry to reorganize its waste streams at source so as to minimize the amount and constitution of toxic materials discharged to a sewer. In this way, and over time, it may be possible to create a sludge that is acceptable even for garden use or for land-reclamation purposes, confining incineration to a small quantity of otherwise non-recyclable materials. Currently, these two approaches are receiving only limited examination, since no mechanism exists for ensuring pursuit of the best practicable disposal option. The United Kingdom government has now adopted a policy of applying best available technology to the removal of the so-called "red list" substances as defined by the European Communities' directives. This move means that increasing attention will be given to removing hazardous substances at source rather than waiting for treatment at the end of the pipe.
Incineration at sea
After World War II, the chemical industry grew rapidly and with it the production of organochlorines. It was common practice to dispose of such waste residues (e.g. EDC-tar, which contains 60-70 per cent chlorine) by dumping, especially in the North Sea and in the Gulf of Mexico. After the Stella Maris incident and the formation of the Oslo Commission and London Dumping Convention, however, organochlorines were placed on "black lists" and incineration at sea was recommended as an "interim technology" (Compaan 1988).
Sea incinerators do not have stack gas-scrubbing equipment because the hydrogen chloride fumes released are neutralized on contact with the sea. This makes them less expensive to run and offers advantages for the disposal of substances (e.g. chemicals with a high chlorine content or fluoridated and salt-rich wastes) that give off large quantities of highly corrosive fumes.
High-temperature combustion or incineration of wastes at sea began in 1969, mainly to dispose of liquid organochlorines (e.g. vinyl chloride and chlorobenzene), relatively stable compounds that are difficult to deal with by any other method. The waste problem has been made more serious by the necessary destruction of relatively pure organochlorines that are no longer permitted for use in the Western world; these substances include trichlorophenol-based herbicides, PCBs, and DDT. The North Sea has received for incineration more waste than have other seas around the world (Compaan 1988, 259). The total amount of incinerated waste at sea oscillates around 100,000 tonnes per year, though there has been a decreasing trend since 1986 in every country that uses this disposal method.
There are three vessels built specifically to deal with the waste, around 68 per cent of which is loaded at the port of Antwerp. The waste is transported to Antwerp by various means, including road, rail, rivers, canals, and sea.
On the basis of the Ministerial Declaration of the Second International North Sea Conference and in accordance with rule 2(3) of Annex IV of the Oslo Convention, the Oslo Commission decided to reduce and ultimately terminate incineration at sea by 1993 (INSC 1990). The decrease in incineration observed between 1986 and 1988 will, therefore, continue.
Countries such as Norway, Sweden, and the former West Germany have already phased out the use of marine incineration, while the Netherlands and France are very close. Switzerland, the United Kingdom, and Belgium are "progressing well," and expect a 65 per cent reduction by 1991 and termination by the required date. The decision to end the marine incineration practice has led to a new challenge to find alternative methods of disposal, usually meaning land incineration. This, in turn, has sparked vociferous complaints by coalitions of active groups that companies are not doing enough to reduce the residuals as a matter of principle. It is likely that the British government will insist on a sharing approach to waste incineration, in which each major waste-producing area will be expected to dispose of its residues locally, rather than seek external locations. Similarly, the European Commission is seeking to establish a policy by which each member state must have its own waste-disposal facilities, even where it is more economic to export wastes across borders. Beyond this, the Commission of the European Communities is proposing a tough civil liability directive that would require waste producers to be responsible for waste-related contamination, irrespective of good practice and whenever it might occur.
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