On the RV lance, our days are alternately spent in open water and surrounded by mesmerising fields of sea ice. The ice takes many forms – glittering bright white sculptures rising from turquise pedestals, broken jigsaw pieces of a flat crust, slushy grey platelets, a near invisible film creeping over the water surface…The larger pieces bang and shriek against the thickened steel bows, behind which our labs are located.
As part of the ACCACIA project, some of us on board are investigating how biological and chemical processes in waters at the ice edge affect the atmosphere above. The spring melt of the ice brings with it a burst of life, as microscopic marine plants (phytoplankton) begin to multiply. To keep track of this change, we will measure the levels of nutrients and the plant pigment, chlorophyll-a, in the water. Anna Dimond is responsible for the round the clock collection and preparation of these samples.
Steve Andrews is analysing air and water samples on board, looking for atmospherically active trace gases such as dimethyl sulphide (DMS) and halocarbons that are produced by the phytoplankton. Between filtering and freezing samples, Anna is also finding time to test for levels of an enzyme implicated in the production of some of these gases.
I am isolating organic matter from seawater, and will compare the compounds I find to those in tiny airborne particles. To collect the latter, I have set up a sampler not unlike a vacuum cleaner on the highest deck of the ship. I hope to discover more about the nature and source of these compounds, as they are thought to affect the properties of the particles, and perhaps ultimately cloud formation.
Each day begins with a CTD cast. A rosette of 12 ten litre bottles, plus an assortment of sensors monitoring temperature, salinity, pressure and light, is lowered over the side of the ship and down into the chilly water. In the ice, the water temperature reads -1.6 degrees Celsius. Once the rosette is back on board and secured in its heated tent to prevent it freezing up, our day of filtering, dripping and bubbling water begins.
Work is punctuated with three excellent hot meals a day, rivers of tea (our Norwegian crew have asked if it is healthy to drink so much!) and trips up to the bridge to scan the horizon for polar bears. We haven’t seen one yet, but are keeping our fingers crossed for the last few days in the ice, before we head back to Tromsø and home. We have seen some whales and dolphins though!