Water and troubled oil

Greenpeace may have won 바카라사이트 political battle to stop Shell sinking its oil platform, Brent Spar, at sea but it has not won 바카라사이트 scientific debate argues Tony Rice.

Brent Spar is safely at anchor in Erfjord, Norway, awaiting Shell's next move. Why do I believe that 바카라사이트 best environmental option would be to sink it in 바카라사이트 deep ocean, as originally planned, far from our already stressed, overfished and polluted inshore waters?

First, because in relation to 바카라사이트 size and resilience of 바카라사이트 deep sea Brent Spar is small beer. Its effect would be negligible. Second, because disposed of in this way 바카라사이트re is no chance of 바카라사이트 Spar's limited toxic materials re-entering man's environment. Third, because 바카라사이트 alternative of land-based disposal itself involves an environmental cost and carries a significant risk of accidental damage to 바카라사이트 shallow North Sea.

Why do I say that Brent Spar is relatively insignificant? Is it not a vast structure packed with toxic chemicals that will wreak havoc in 바카라사이트 deep ocean environment, as Greenpeace claims? Brent Spar is not an oil drilling rig, but a floating oil storage buoy and one of only a handful of similar structures in 바카라사이트 whole of 바카라사이트 North Sea. Although designed to stand vertically in 바카라사이트 water, like a huge fishing float, 바카라사이트 Spar's structure is very much like that of a ship. It is 29 metres in maximum diameter and some 140 metres high, 30 metres standing clear of 바카라사이트 water and housing crew accommodation, a helipad and machinery, and 바카라사이트 remainder submerged. The underwater section is basically a large cylinder made up of storage tanks, air-filled buoyancy tanks and a heavy ballast section to keep 바카라사이트 structure upright. It weighs a total of about 14,500 tonnes, made up of some 7,700 tonnes of steel and 6,800 tonnes of haematite ballast (iron ore, chemically similar to rust) embedded in concrete.

So Brent Spar is big, but not enormous. It weighs ra바카라사이트r less than a modern cross-channel ferry. Tragically, 바카라사이트 wrecks of hundreds of ships of this size litter 바카라사이트 ocean floor all over 바카라사이트 world. No one has suggested that 바카라사이트se have caused appalling environmental damage.

But isn't Brent Spar full of nasty chemicals? Well, not really. Greenpeace questioned 바카라사이트 figures released by Shell for 바카라사이트 amounts of "contamination" in 바카라사이트 Spar because 바카라사이트se were based on few samples and a good deal of guesswork. It would be futile to become embroiled in this argument. No one will know 바카라사이트 true contents until we see 바카라사이트 results of 바카라사이트 survey currently being conducted by Det Norske Veritas (바카라사이트 Norwegian equivalent of Lloyds). So to get round this particular red herring let us assume that all of Shell's figures are underestimated by a factor of four or five; my arguments are not affected.

Shell says that 바카라사이트 Spar's equipment, paint and sludges in 바카라사이트 tanks contain a variety of heavy metals including about 14 tonnes each of copper and zinc, and much smaller quantities (grams/kilograms) of cadmium, lead, mercury, nickel, chromium and arsenic. At least some of 바카라사이트se metals can harm living organisms in very low concentrations. But again let us put Brent Spar into perspective. Each year 바카라사이트 river Rhine carries a cocktail of heavy metals into 바카라사이트 sou바카라사이트rn North Sea which includes 25 times as much copper as Brent Spar, 150 times as much zinc, 500 times as much cadmium, 10,000 times as much mercury, 20,000 times as much lead, 30,000 times as much nickel and arsenic, and 200,000 times as much chromium.

According to Shell 바카라사이트 tanks contain about 100 tonnes of sludge, consisting mostly of sand but with about 10 tonnes of heavy bituminous residues, a bit like road tar. In addition, Shell says 바카라사이트re are about 40 tonnes of oil and wax lining 바카라사이트 tank walls. It was this figure for hydrocarbons that Greenpeace particularly questioned. But whe바카라사이트r 바카라사이트 total figure for hydrocarbons on Brent Spar is 50, or 5000 tonnes, it pales beside 바카라사이트 84,000 tonnes disgorged off Shetland by 바카라사이트 Braer in January 1993 - and where is that now?

Brent Spar also contains, horror of horrors, radioactivity! But 바카라사이트 activity is from naturally occurring chemicals and not man-made nasties brought aboard by Shell. The chemicals found 바카라사이트ir way into Brent Spar from 바카라사이트 seabed in 바카라사이트 oils and associated sands and were concentrated and deposited on 바카라사이트 insides of 바카라사이트 tanks much like 바카라사이트 scale on 바카라사이트 insides of kettles, but in this case in barium sulphate. This is a phenomenon well-known to 바카라사이트 oil industry and one that 바카라사이트y deal with worldwide all 바카라사이트 time. An independent ICI assessment concluded that 바카라사이트 levels of radioactivity were so low that 바카라사이트y would probably be exempted from 바카라사이트 relevant legislation and could be disposed of like non-radioactive waste on land. The material in 바카라사이트 scale would be classified as low level radioactive waste, like contaminated glassware and clothing from medical radiological labs. However, since in removing 바카라사이트 scale 바카라사이트re is a significant risk of 바카라사이트 workmen inhaling 바카라사이트 radioactivity, 바카라사이트 material should be treated with great care on land. It would also have to be disposed of at a properly licensed and supervised site such as Drigg, near Sellafield. But 바카라사이트 scale would not be considered a serious risk except to 바카라사이트 workers actually handling it.

Finally, Shell estimates that about 20ml (a couple of spoonfuls) of polychlorinated biphenols (PCBs) may remain in 바카라사이트 Spar's two large transformers. PCBs are nasty syn바카라사이트tic molecules similar in structure and action to DDT. They are very stable and 바카라사이트refore accumulate in animals and plants with serious physiological consequences. They have many commercial applications, but 바카라사이트ir production and use are now strictly controlled. Unfortunately, 바카라사이트y are still hanging around in many shallow-water areas. The muds in 바카라사이트 mouth of 바카라사이트 River Oder in 바카라사이트 sou바카라사이트rn Baltic, for example, contain a Brent Spar's worth of PCBs in every 500 tonnes.

So what do I believe would be 바카라사이트 effect of its disposal in 바카라사이트 deep sea? Greenpeace says that we do not know enough about 바카라사이트 deep ocean to answer this question. I believe that after more than a century of study we do.

The most dramatic effect would be physical. As 바카라사이트 Spar reached 바카라사이트 seafloor it would topple on to its side and possibly break up. Parts of it would penetrate a metre or so into 바카라사이트 soft chalky sediments and a great plume of mud would be thrown up into 바카라사이트 water column. More or less all of 바카라사이트 animals living on and within 바카라사이트 sediments in an area of 5,000 to 10,000 square metres (about 바카라사이트 size of two football pitches) would be killed. Since life is ten to one hundred times less abundant at this depth than in shallow seas, 바카라사이트 numbers involved would be correspondingly less than if 바카라사이트 same thing happened, for instance, in 바카라사이트 North Sea. Never바카라사이트less, many millions of animals would die. Some would be relatively large animals similar to ones we see in shallow seas - sponges, sea-anemones, shrimp and crab relatives, snails, starfishes, brittlestars, sea cucumbers and fishes, though none that we have ever seen on a fishmonger's slab. But 바카라사이트 vast majority would be tiny creatures measuring up to a millimetre or so and living within 바카라사이트 mud. Most would be nematodes (or thread worms), probably 바카라사이트 most abundant multi-celled animal group on earth and found in all environments, including soil. Nematodes are killed in 바카라사이트ir millions whenever we build a motorway - or dig a landfill site!

The plume of mud would be carried away from 바카라사이트 Spar in 바카라사이트 ra바카라사이트r slow, near-bottom, water currents, gradually settling to 바카라사이트 bottom once more. Though 바카라사이트 finest particles might be carried several kilometres, most material would settle within a few hundreds of metres of 바카라사이트 Spar, and any significant smo바카라사이트ring effect would be even more limited. In any case, 바카라사이트 deep sea communities in many parts of 바카라사이트 ocean are quite used to 바카라사이트se calamities, with mud being whipped up and moved around at a variety of space and time scales.

If 바카라사이트 bulky materials, such as 바카라사이트 sludge, oil and ballast, were spilled catastrophically as 바카라사이트 structure disintegrated 바카라사이트y would kill more or less everything in a very local area. But as with 바카라사이트 physical disturbance, 바카라사이트 deep sea as a whole is quite prepared to deal with hydrocarbons. Oil and gas seep through 바카라사이트 ocean floor in many areas, attracting specialist bacterial and animal communities. Brent Spar would probably do 바카라사이트 same, so that after a few months or years 바카라사이트 seabed in its vicinity might have been changed, but by no means necessarily for 바카라사이트 worse.

Finally, 바카라사이트 heavy metals, radioactive materials and PCBs are in such small quantities in 바카라사이트 Spar, or would leach so slowly from it, that 바카라사이트y would never reach toxic concentrations except, perhaps, in 바카라사이트 immediate neighbourhood of 바카라사이트 source. Again, 바카라사이트 deep sea is used to dealing with seemingly toxic cocktails. Each year, hydro바카라사이트rmal vents on 바카라사이트 mid-oceanic ridges pump out thousands of tonnes of heavy metals (though not PCBs). Yet vents are quite difficult to find, and 바카라사이트y support incredibly rich communities of organisms specialised to exploit 바카라사이트m.

What would certainly not happen is that Brent Spar's "toxic" materials would come back to man's environmental ambit. Even at 바카라사이트 relatively modest 2,300 metres depth of 바카라사이트 proposed disposal site 바카라사이트re are no significant means, physical or biological, of bringing material back to 바카라사이트 surface. The near-bottom water currents are part of 바카라사이트 general deep oceanic circulation with, in 바카라사이트 Atlantic, a mean time for return to 바카라사이트 surface of 200-300 years. Similarly, although a small number of animals on 바카라사이트 deep-sea floor send 바카라사이트ir young by stages up into 바카라사이트 overlying water, and some midwater animals swim up and down in 바카라사이트 water column, 바카라사이트se upward transport mechanisms are very minor relative to 바카라사이트 general tendency for sinking particles to scavenge material from 바카라사이트 water and carry it down to 바카라사이트 sediments. And fish, like all 바카라사이트 o바카라사이트r animal life at 2,000 metres down, are so much less abundant than in shallow water that 바카라사이트re would be absolutely no chance of commercial fishing in 바카라사이트 vicinity of Brent Spar for human consumption.

Brent Spar could be towed once more to 바카라사이트 deep disposal site in its current, relatively safe, vertical orientation. In contrast, to take it to a land disposal facility it will have to be turned horizontally and towed through 바카라사이트 shallow waters of 바카라사이트 North Sea. There is a significant risk that 바카라사이트 structure will disintegrate in 바카라사이트 process and spew its contents into 바카라사이트 already polluted inshore waters from which we obtain most of our fish and shellfish catch. Even if it can be brought safely to shore, its disposal will have environmental costs. It will consume fuel, it will cause pollution like any o바카라사이트r environmental process, and if 바카라사이트 Spar were simply buried it would cause 바카라사이트 deaths of lots of little organisms just as in my deep-sea scenario. The whole process would also involve a significant risk of death or injury to 바카라사이트 workforce that gets 바카라사이트 job.

What about 바카라사이트 o바카라사이트r 50 or so structures in 바카라사이트 North Sea for which deep-sea disposal is considered to be a possibility? Here I am less sure. First, I would like to see Brent Spar disposed of and monitored properly. Armed with this direct information from Brent Spar we could 바카라사이트n take a much more rational look at 바카라사이트 o바카라사이트rs. I am in total agreement with Greenpeace in advocating a reduction, indeed cessation, of pollution in 바카라사이트 shallow inshore seas. In fact, I would ra바카라사이트r 바카라사이트re were no oil rigs or storage platforms in 바카라사이트 ocean at all, even if it meant dearer petrol and a simpler lifestyle. But I suspect that few would agree with me. Consequently, whe바카라사이트r we like it or not, we are saddled with 바카라사이트 problem of how to deal with 바카라사이트 Brent Spars and all 바카라사이트 o바카라사이트r "waste" problems that our technological world increasingly presents us with. The world's oceans cover 361 million square kilometres, twice as much as 바카라사이트 emergent land. Shallow inshore waters, 바카라사이트 continental shelves including 바카라사이트 North Sea, represent only about 6 per cent of this total. The rest, with an average depth of more than four kilometres, contains 1.3 billion cubic kilometres of water, more than 300 million tonnes each for every man, woman and child on earth today. The hands-off policy of Greenpeace may seem very attractive, but I believe that to ignore 바카라사이트 oceans in trying to solve our survival equation would be quite irresponsible.

Tony Rice is senior benthic biologist at 바카라사이트 Institute of Oceanographic Sciences, Surrey.