Scientists are looking at what impact volcanic ash from the recent eruption in Iceland has had on marine biology.
A team of researchers will spend a month at sea, studying a region of water in the North Atlantic.
They say the information will provide "unique data" on how the dust affects the chemistry and biology of seawater.
The eruption under a glacier in south-west Iceland created a vast ash cloud that spread across northern Europe.
"It is a very interesting and unique situation that we find ourselves in," said Eric Achterberg from the UK's National Oceanography Centre, which is leading the study.
"It will provide an angle that we did not expect."
Professor Achterberg said that the research cruise was originally planned about three or four years ago, and it was by chance that the study coincided with the eruption.
"We are interested in the sub-polar region of the North Atlantic, which is the area just south of Iceland and Greenland.
"We will be sampling the particles in the atmosphere and chemicals in the rainwater," he told BBC News.
"This means that we can calculate what is falling into the oceans. We will also measure the chemicals in the ocean, and we're particularly interested in elements like iron, but also nitrogen, phosphorous and silicon."
The team will use the measurements to link them to the rate of growth of phytoplankton - microscopic plants.
"It is a region of water that normally has very low inputs of iron and other nutrients from the atmosphere," Professor Achterberg explained.
"Our assumption is that phytoplankton are growing in a sub-optimum manner because of a lack of iron. It is like your garden; if you do not add enough manure, then the plants do not grow as well."
However, he suggested that iron contained in the ash cloud from last month's eruption of the volcano beneath the Eyjafjallajokull glacier could trigger prolonged phytoplankton blooms.
Focus on CO2
"You may have an extra input of iron, which will upset our original hypothesis that the region runs out of iron during the summer."
The expedition - aboard the RRS Discovery, a Natural Environment Research Council (Nerc) vessel - is part of a climate change project that is looking at the efficiency of phytoplankton to absorb atmospheric CO2 and sequester it in the deep ocean.
"The plants take up an awful lot of CO2 from the atmosphere," Professor Achterberg said.
"So if they are growing at a sub-optimal level, then they are not taking up all of the CO2 that they potentially could."
The 26-strong team of researchers and technicians will return to the UK at the end of May, and plan to release its findings soon after.