Homage to Gaia (39 page)

I flew to Hamburg in 1973 and a scientist from the ship met me, and took me to a pension near the port where many of the ship’s company were staying. I was deeply aware that in the Second World War Hamburg had suffered the greatest civilian casualties of any bombing raid during the whole of that war, even more than were caused by the atom bombs in Japan. Close to 250,000 died in one night of intensive bombing, far beyond anything we had suffered in London. I was amazed at the extent to which they had rebuilt the city. No scars were visible to me in my journeys across it, nor did I detect any personal animosity towards me as a representative of the tribe that had so barbarously executed the terror bombing.

The next day, after breakfast, we climbed into a station wagon with our suitcases full of personal belongings and clothes to wear on the voyage. I had some spare old clothes, one good jacket in case of need, and some books to read. The journey to the dock was short, and soon we were wending our way past port cranes hunched mournfully against the morning sky, and past warehouses full of boxes and men with forklift trucks. Of all the working scenes, none has quite the capacity to move me like that of a dock area. The foreplay of
preparation for a sea voyage has an excitement more than that of any other journey. Air travel is a dull thing by comparison; mostly a set of encounters with officials and bureaucrats in a peculiar kind of
air-conditioned
office called an airport. If all one’s papers satisfy them they dispatch you down a pipe like one of those pneumatic account carriers that added mystery to the old-fashioned department store.

We left the car and looked at the sizeable bulk of the
Meteor,
not at all like the tiny
Shackleton.
Here was a shipshape floating palace full of laboratories. One of the ship’s officers took me up the gangway and to a spacious top deck cabin, and here I met Dr Rai Rasmussen, an American scientist who was to share the cabin with me for the voyage. I was somewhat dismayed to be sharing a cabin. I am a private person and do not like sharing living quarters with strangers, but there was little I could do about it. As it happened, I soon found that Rai Rasmussen was a quiet and courteous person at close quarters. We soon, as the only two foreigners aboard the ship, were driven together and spent the voyage amicably. After settling in I went down to the lab assigned to me where I found the box with all of my equipment waiting. I spent the rest of the morning connecting it up, and by lunchtime my gas Chromatograph was running. There was a spacious bench for me, and an excellent drawer and cupboard space below it. A friendly German graduate student who, like so many Germans, spoke English better than many of my countrymen, occupied the other half of the lab.

There was a spacious and well-equipped dining room on the
Meteor
and I looked forward to an encounter here with the German scientists who were to travel with me down the Atlantic to Santo Domingo. I had hoped to improve my German during the voyage to the point of colloquial conversation. It was not to be. Not even the sailors on deck would speak to me in anything but English. They always replied to my halting German phrases with a rejoinder in near perfect English, not rudely, but because life was too short to waste time over a mismatch in language. Lunch, indeed all lunches on the
Meteor,
were substantial German meals. To my taste, they were disappointing and too rich, but they were more than adequate for health. I missed the near gourmet food of the
Shackleton
and of the Navy ships. Breakfast, thankfully, was no continental breakfast of coffee and rolls. There was more, and it was adequate. The other meal, high tea at 5 o’clock, was the hardest to cope with: just quantities of bread and butter and a variety of cold sausages. I longed for some fresh fruit and vegetables, but there were
none. Food is very much a cultural affair, and no doubt Hans, my companion on the
Shackleton,
would have found something to complain about with our food. There was a shop on the ship where Rasmussen and I bought chocolate to satisfy our craving for
something
sweet.

We set sail soon after we had boarded the ship, and in the afternoon I saw something of the flat landscape that bordered the Elbe estuary. It was a clear day and a wide sky, so beloved of Flemish painters, illuminated the smooth movement of the ship. The open decks were spacious and there was plenty of room to walk and to explore. In the evening I made the first chlorofluorocarbon measurements and found them to be well over 300 parts per trillion. This was unbelievable, for we were already out in the North Sea and the wind was off the sea, not the land. I soon discovered that the CFC level in the ship itself was so high, approaching one part per million, that measurement of CFCs in the lab on the
Meteor
was all but impossible with the equipment I had brought with me. The heavy halocarbon contamination came from several sources: some meteorologists aboard the ship had filled Dewar flasks with chlorofluorocarbons, from which CFCs vented to the ship’s air. Other scientists were using carbon tetrachloride as a solvent for Vaseline, which they coated on glass slides. The sticky slides were then used to collect aerosol particles in the air the ship passed through. Most of the ship’s company also used aerosol sprays
powered
by chlorofluorocarbons as deodorants and for shaving soap. The tightly closed and air-conditioned quarters of the ship kept the air inside and these rich sources caused the
Meteor
to have the highest concentration of halocarbons in any air I have ever measured. It was not the place to monitor atmospheric CFCs.

I had looked forward to seeing the Straits of Dover as we passed through that narrow part of the Channel, but it was dark and all that I could see were faint lights on shore. The ship moved comfortably in the Atlantic swell that came up the Channel. It was a more stable platform to work on than the
Shackleton
had been. I noticed no one seasick, even on the first day, and the whole voyage seemed to be one of unusually calm weather. Rai Rasmussen was busy measuring
hydrocarbons
in the air and in the water. He used a far more expensive and complicated commercial gas Chromatograph. He was curious about my simple gas Chromatograph and astonished to find it over a
thousand
times more sensitive than the equipment that he was using. It may have been his first encounter with electron capture gas
chromatography. The ECD was so sensitive, so unpredictable, and so little understood that analysts regarded it with suspicion.

Science to me has always been something to wonder about and to have the daily ration of curiosity satisfied by successful experiments: to speculate then experiment, measure, or calculate. To my travel companion, science was a battleground, with castle walls to be
breached
or clambered over. He looked like his name, Rasmussen, a Viking. He had the Viking’s untamed ambition and desire to win whatever the cost. When I said I would abandon my
chlorofluorocarbon
study because of the ship’s excessive contamination, his response was to urge me to demand immediately the banning of aerosols by the crew and scientists aboard. Fortunately for both of us, I knew how easy it is to upset a ship’s company. It would not be a good idea to interfere with the daily routine of life unless the cause was truly serious; moreover, we were guests on a German ship. When I said, ‘No, I’m going to find some other project to occupy me on this voyage and forget the CFCs’, I think Rai Rasmussen regarded me as a wimp, albeit a talented one.

What makes me an unusual scientist is a capacious and immediately accessible memory. Anything I read, or hear, or see that interests me stays with me and is available. I have never used card indexes or computer databanks. I try to keep it all in my head. It says something of the deficiencies of my character that this memory is not available for people’s names, which I forget within seconds of hearing them. My memory, and some forethought during packing at Bowerchalke before the voyage, gave me a second project. I had included in the box sent to the ship several gas Chromatograph columns that were suited to the analysis of other compounds than the
chlorofluorocarbons.
I did this because I expected to find on the voyage some other interesting substances in the air or the sea. The speed with which substances pass through a gas Chromatograph column and appear at the detector is characteristic of their nature and can help to identify them. With several different columns, each of which has a different speed of passage for any given substance, the identification becomes more certain.

I noticed that after standing on the deck my skin and my shirt had a strong chlorine-like odour and I remembered that the notorious air pollutant called PAN smelt like chlorine. This is a peculiar substance, discovered as a major component of Los Angeles smog by the American scientist, ER Stephens in 1956. The pure substance is so
dangerous that experimenters usually handle it as a dilute
concentration
in air or some inert gas. Pure PAN explodes violently at any number of pretexts, which include contact with rough surfaces,
exposure
to bright lights or sudden warmth. Therefore, we avoid ever using it. For those interested, the letters PAN are the initials of the word peroxy-acetyl-nitrate.

It so happened that I had brought with me a column just right for the analysis of PAN. It was filled with a powder coated with
polyethylene
glycol. I joined it up in place of the CFC column of my gas Chromatograph, went on deck, and collected a few air samples. Sure enough, when I applied them to the Chromatograph a peak appeared on the recorder at the time that I expected PAN to appear from the column. There were also three other peaks whose identity I did not know. I tried the same measurement a few more times and with the same result. I speculated that if this were PAN then it was in an air mass that had drifted from Europe into the air above the Atlantic. Here was a simple project for me. I could take daily measurements and follow the ship’s passage through and out of the polluted air mass. I wished that I could have measured chlorofluorocarbons as well, to confirm the urban origins of the PAN, but it was not to be.

As the days went by, we moved west and south, ever further out into the Atlantic. To my surprise, the PAN in the air increased rather than decreased and was present even when the air was obviously clear, sparkling, and free of smog. My guess that it came from some distant pollution source looked to be wrong. Where could it have come from, so far out over the ocean? As we sailed further south, the sunlight increased, and it became warm enough on deck for open shirts and shorts. The PAN increased still more in abundance, although we were further than ever from land. It could not have come from a maritime industrial source, such as a fleet of fishing vessels and factory ships, for we were now in the notorious Bermuda Triangle, where few ships ever go. I asked permission to go out far away from the
Meteor
in a rubber boat and collect just a few CFC samples to confirm that we were truly away from urban industrial air masses. Permission was given and a German sailor took me in a zodiac-type craft about a mile away from the ship, which was at the time stationary. It was quite eerie to be in this boat and look back across a mile of empty ocean towards the small image of the
Meteor
waiting there. I felt as the astronauts must have done on seeing the Earth from the Moon, so small it was and so far away. I hastily gathered my clean air samples and the German sailor
grinned and pointed to the
Meteor.
He was glad, like me, to be returning to our home.

When I analysed the clean air samples they showed the expected northern hemispheric background level of CFCs, about sixty parts per trillion: this was no smoggy air mass. I began to collect PAN samples throughout the day and soon found that the level varied with the position of the sun. There was little at dawn or dusk and the
maximum
in the early afternoon. So the photochemistry that made it must be local; the sea must be emitting hydrocarbons and nitrogen compounds. Rasmussen confirmed that the sea was a source of hydrocarbons and I now know from the work of my friend, Peter Liss, that it is also a source of amines. These nitrogen compounds would oxidize in the atmosphere to give the nitrogen dioxide from which PAN can form.

We were now well into the Sargasso Sea; everywhere were fronds of seaweed, Fucus-like, with bladders to keep them afloat. They were not dense and entangling but sprinkled over the waters of a clear blue sea. Nature has a way of leading scientists up the garden path and then suddenly removing the garden. For reasons I now forget, I sampled the air the next day with a polypropylene syringe, instead of the glass ones I usually used. To my dismay, the PAN had vanished. I tried again with the glass syringe, and there it was back again. Was the polypropylene surface destroying PAN? Unlikely, I thought. I would have expected the reverse, for PAN decomposes on glass surfaces but is stable towards polypropylene. I then tried
incorporating
a piece of glass wool into the polypropylene syringe and the PAN came back again in full quantity. It looked as if what I had thought was PAN in the air was in fact PAN coming from the reaction of
something
in the air with a glass surface. This was even more mysterious. What could be in the air out over the ocean that reacted so rapidly on the surface to make PAN? I could only guess that it was a mixture of nitrogen dioxide and a free radical precursor such as the acetyl peroxy radical. I knew that the methyl peroxy radical was a common product of methane oxidation, which goes on everywhere. Was the product of its reaction with nitrogen oxide also present? There was certainly always a peak well before PAN which, like PAN, was present only when the sun shone. Having no means of proving it or its precursor’s presence, I can only guess that methyl peroxy nitrate was also there, forming on surfaces in this clear remote place. This odd phenomenon kept me occupied until we reached our destination, Santo Domingo.
The results of these preliminary investigations appeared in a
Nature
Letter, called ‘PAN over the Atlantic and the smell of clean linen’ in 1974.