TUESDAY. Watching the sun set from 25,000 feet over Moscow on my way to Irkutsk, central southern Siberia, I find myself trying, somewhat unsuccessfully, to put to the back of my mind a recent television documentary on vodka-swilling Aeroflot pilots. Although the flight should take about six hours, the good news is that the stewardess has put me in what passes for business class in a Tupolov Ty-154. The bad news is that she adamantly refuses to serve me alcohol.

WEDNESDAY. Met from the plane by my host, Paval Koval of the Vinogradov Geochemical Institute, Irkutsk, only to be told that we would be leaving immediately for the field. With barely time to change, I am bundled into the back of a Soviet army jeep and driven for nine hours through the Siberian interior to Olkhon, the largest island in Lake Baikal. A welcome break from the heat and petrol fumes when a stone shattered the windscreen. Reprieve, alas, was temporary as within a few minutes the vehicle was filled with road dust. The drive was punctuated by stops for chai (tea). Arrival at Olkhon Island, after a short ferry trip, was celebrated by vodka and an offering of roubles and cigarettes to the Gods of Baikal.

THURSDAY. We have set up camp on the shore of Baikal - a beautiful sandy beach looking west towards mainland Siberia. There are 12 of us here, four scientists, seven ancillary staff including two drivers, and two women who do all the cooking, and a mystery man whose sole purpose seems to be to play a relentless succession of Russian love ballads as loudly as possible from a transistor radio rigged to his car battery. The food, mostly a mixture of salad, potatoes and baked fish, is very good. Unfortunately, I am still not quite ready for breakfasting on neat vodka. Spent most of the day collecting soil samples for heavy metal analysis, and making measurements of radon gas.

FRIDAY. Woken at about two am by the most incredible thunderstorm. I knew we were in trouble when Poval suggested we use our plastic groundsheet to supplement the canvas of our tent. So, out we got in our underwear. The noise from the thunder was incredible. I have never been saturation bombed by a squadron of B-52s, but I bet it is not dissimilar. As the guest westerner, I was given the one camp bed to sleep on, so at least I am not lying in soaking wet sand.

ÁñÁ«ÊÓƵ

SATURDAY. Today I was cleansed. This process of spiritual redemption involved clambering from one side of a large lump of lake-side rock to the other side through a tunnel, in near-total darkness. The rock is one of Buddhism's most holy sites. With typical respect for the religious feelings of the native Buryat people, Soviet authorities turned it into a dock to unload diesel fuel. The most fraught moment occurred when I realised the tunnel beneath my feet had all but vanished, leaving me stranded in blackness. One false step and I would have crashed on to rocks below. Somehow I made it through the tunnel, noting as my eyes got used to the dark that many of the large boulders hanging precariously in the roof were only held there by rotting timber. Emerging I was met on the other side by a small child gutting a fish, and looking distinctly unimpressed. Apparently, the passage was discovered long ago by a local shaman, who could negotiate his way through the rock so quickly that the local inhabitants came to regard him as a demi-god.

SUNDAY. Travelled south to the main settlement of Khuzhir, pausing only briefly to pick up a happy camper who had managed to remove a section of his left foot while chopping wood. The United States ambassador to Russia, one Thomas R. Pickering, is also in town today, apparently to discuss the future of US funding of environmental research. The US Agency for International Development is currently financing a four-year, $3-million project to promote environmentally sustainable economic progress around the lake, the biggest body of fresh water on earth. The problem is that if Congress goes ahead with its proposed cuts in foreign aid, the Baikal project will face the axe.

ÁñÁ«ÊÓƵ

MONDAY. Morning spent collecting more soil samples, and cataloguing many of the species of grass that grow around the island. Geographically, the region is similar to the Mongolian Steppe, some 500km to the south. Our botanist, Gregory, tells me that much of the flora found here is similar to that of English chalk.

His ambition is to come to England and walk the downs. The scenery, with its softly undulating hills, is very similar. In the afternoon we made an unscheduled stop at a local farm. It took me a while to realise that we were there to collect our food for the following week - the only problem being that it was still alive.

The Mongolian way of killing a sheep is not for the squeamish, but involves surprisingly little bloodletting. After witnessing the slaughter, and as the carcass was hacked into transportable chunks, I realised that if I were ever destined to be a vegetarian it must surely be now.

TUESDAY. I am sick of sheep meat already.

NICK PETFORD Senior lecturer in the school of geological sciences, Kingston University.

ÁñÁ«ÊÓƵ