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There And Back Again: Returning To The South Pacific

Last year I was told that my fieldwork in Samoa and New Caledonia was the best I’d ever experience; turns out that was a lie. This year I was fortunate enough to return to Samoa, and even more fortunate to go to the small island of Atiu in the Cook Islands. There was one very simple reason for me, along with Prof. David Sear and Dr Pete Langdon, to return to the South Pacific: we needed more sediment from the lakes on these islands. This sediment is crucial to determine how a massive band of rain – called the South Pacific Convergence Zone (SPCZ) – has moved in the past. Millions of people are dependent on the SPCZ for drinking water. Data from satellites has shown that various climatic phenomena that operate in the Pacific Ocean cause the South Pacific Convergence Zone to move. With future climate change likely to strongly affect the SPCZ and cause it to move, it is vital that we understand how it has moved in the past so that we can predict how it will move in the future.

We left London Heathrow for a somewhat gruelling 30-hour transit to Atiu to take cores from Lake Teroto. Shortly after arriving we began work obtaining wood from the local coffin maker to make our coring platform. We needed this to not only support us but to hold aluminium casing which we would be sending the corer down. It was at this point that we discovered the value of our helper Koro – a truly remarkable man. Koro is one of an increasing number of Polynesians who is navigating the Pacific on double-hulled canoes using the stars as his guide just like his ancestors did. He helped us create our coring platform; had an intuitive knowledge of what we needed help with before even asking; and climbed up coconut trees to get us fresh coconuts to drink from when working under the tropical sun. With his help we managed to obtain eight metres of sediment from the bottom of the lake: more than enough for me to work on over the remainder of my Ph.D.! What was even more exciting than the amount of mud we obtained was that we found some of it had distinct layers. This is really intriguing as layers such as those could indicate that sediment was being deposited at specific times of the year, allowing us to look at annual changes in the Lake Teroto record.

Following our week in Atiu we went on to Samoa to collect samples from Lake Lanoto’o. Having been to this lake last year we were well prepared for what was in store: red mud that got absolutely everywhere, and leeches that had a remarkable knack for getting in unusual places. It was in Samoa that we were joined by Georgia Eves – an undergraduate student who will be working on the samples obtained here for her dissertation. Georgia did a fantastic job, getting her first chance at using a corer and obtaining sediment from this fascinating lake. We managed to obtain three metres of sediment from the lake – the most that has been taken to date! Following this success we immersed ourselves in Samoan culture, visiting the local flea market for souveniers – a coconut bra or two may have been purchased… We spent our final night in a beach fale, this being a hut on a beach, and watching Samoan firedancing: a truly spectacular sight.

At times gruelling, yet always enjoyable, this fieldwork expedition was not only our most successful but definitely the most enjoyable. Here’s to hoping we can return to the South Pacific again soon.

BEARS, BUGS & BUSH PLANES – LAC FIELDWORK IN ALASKA

Ruppert Lake.  Photo: K. Davies

Ruppert Lake. Photo: K. Davies

When the floatplane left us at Walker Lake, it was just the five of us and a large pile of camping and coring kit that would keep us busy for the next twelve days or so. As the humming of the engine and the waves died away things became very quiet for a moment and we were all awed by the view over Walker Lake against the backdrop of the Brooks Range. Welcome to one of the last wild places in the world! This quiet, contemplative moment only lasted briefly as a cloud of mosquitoes formed around us.

We had come to this place at the southern margin of the Brooks Range to core three lakes. We hoped that the sediments in those lakes would contain an environmental history of the past 10.000 years. Our NERC-funded project, Lakes and the Arctic Carbon cycle (LAC), had just started and we were going to investigate how large-scale changes in the landscape had influenced lakes in the past. As a result of changes in temperature and precipitation the vegetation in the Arctic has changed dramatically since the last ice age, going from tundra, to shrub-tundra to boreal forest. In turn, this led to an increase of soil development and nitrogen fixing by species like alder. We know how these processes work to some extent from previous research projects, but we don’t know yet how these developments on the landscape scale influence lakes. We want to know about lakes because they can play an important role in storing carbon in their sediments (dead plants and animals) or releasing it to the atmosphere (CO2 and CH4). By coring lakes we can create records of vegetation change using pollen and plant macrofossils that are preserved in the sediment. Next, we can compare these with records of in-lake changes using remains of diatoms (a group of algae), invertebrates and pigments. We can also look at the geochemistry of the sediments using techniques such as XRF scanning (X-rays of the cores), and stable isotope analysis (Check here for a great explanation of stable isotopes and another great science website!). This way we can try to understand how they are related to each other, which will also inform us about similar processes that are going on today as climate change strongly affects high latitude regions. By coring lakes across the Arctic we hope to get a larger picture, which is why colleagues have already cored lakes in Greenland and Siberia, and why we are here in Gates of the Arctic National Park, Alaska.

The park ranger had told us very clearly that we would have to keep a clean camp and to have different places for sleeping, cooking, and storing food. The reason for this is that food, fuel, and other human items like toothpaste smell irresistibly interesting to bears. It would perhaps have been nice to see a bear in the distance at some point, but we were so well equipped to keep bears away that the chance we’d see one was rather slim. We had bear-proof barrels to store our food, an electric fence around the stored food, at least one can of pepper spray each, jingling bells, a shotgun (and training to use it), and a motion sensor alarm (“Critter Gitter”). The latter gave us a couple of sleepless nights chasing off birds, branches, and perhaps (?) a bear. Twice, a moose came grazing when we were coring and one of our lakes was home to a beaver, but we never saw a bear during our trip.

The most unexpected thing we experienced in the arctic was the intense heat and baking sun. Which is great if you’re on holiday, but not ideal when you’re carrying several 20-30 kg kit packs half a mile uphill, wearing long sleeves and a mosquito net that prevents you to breathe in fresh air. But we really needed all of our equipment: two boats, boards and ropes to build a platform. The adjustable sediment corer with several meters of extension rods, liners, pistons, and cable. Tools and water sampling equipment. Material to extrude, wrap and package cores. Plus an extra boat to shuttle kit and people to and from the platform.

After taking several cores totalling 12 m of mud at Ruppert Lake, we moved everything another half a mile through thick brush to three previously unstudied lakes that we hoped would have enough sediment in them. At one lake we were successful in retrieving 2.25 m of sediment until we were stopped by a layer of coarse wood (for which we wanted to baptize the lake ‘Woody Bottom Pond’, but in the end gave it the much more exciting name ‘Lake 3’). In all, we brought back almost 25m of sediment weighing 150 kg, that will keep us and other project partners busy for a while.

There is one thing that is so easily forgotten when you’re focused on getting all the right cores. And that is to look around you, to take in the landscape, the reflection of the trees and the mountains in the water, the raven flying in the distance. Listen quietly to the silence, and draw in fresh air. The Arctic has always attracted me, perhaps because life seems more simple there, uncontaminated by the modern day rat race. You will need to survive, of course. Survive the cold and dark winters, the wild animals, the bugs, the alcohol. Call me a romantic fool, but life is different out there. And at the end of the day the most fantastic thing to do is bathing in the clear, cold, still water of Walker Lake. The midnight sun setting in warm purple colours below the mountain tops.