Leicester geoscientists return from expedition following successful offshore operations
The Liftboat Robert. Photo: Everest@ECORD_IODP3_NSF
An expedition to collect samples of water sealed below the sea floor for potentially thousands of years that University of Leicester scientists played a key role in has completed its offshore phase successfully.
Seventy-four days offshore, 718 cores, 871.83 meters of total core from three locations – this is the first outcome after the end of offshore operations of IODP³-NSF Expedition 501 ‘New England Shelf Hydrogeology’. The goal of the expedition was to take samples not only of sediment cores, but also of the water stored in sediment, both sandy aquifers and clayey aquitards beneath the ocean floor. Their existence has been known for decades but they remained virtually unexplored – until now.
The expedition is a joint collaboration between the International Ocean Drilling Programme (IODP³) and the US National Science Foundation (NSF). For the first time scientists managed to take water and sediment samples from beneath the ocean floor on the New England Shelf with the intention of understanding this offshore aquifer system.
Together with its IODP3 operator partners from the British Geological Survey, MARUM (University of Bremen, Germany), and the University of Montpellier (France), the University of Leicester facilitated this international expedition. Four geoscientists from the University of Leicester worked in shifts onboard the science vessel, the Liftboat Robert, measuring and studying the physical and chemical properties of solids (e.g. the sediments) and liquids (e.g. water).
Professor Sarah Davies, Professor of Sedimentology and lead of the IODP3 group at Leicester, says: “Leicester’s specific expertise and contributions, working in collaboration with colleagues from Montpellier, will be critical in helping to unravel the story behind these groundwater systems. Our measurements, both on core samples brought back to the surface and directly from the borehole below the seabed, play a key role in this effort. For example, we can align cores with the borehole using natural gamma ray data, while resistivity measurements are particularly important for this expedition as they relate to the changing interstitial water salinities.
“In addition, we introduced new techniques, including the downhole Borehole Magnetic Resonance measurements to understand porosity and permeability of the sediments.
“This offshore phase of the expedition provided the operations and science teams with new and exciting challenges which ultimately led to a highly successful expedition. The success is a testament to the dedication, expertise and enthusiasm from an innovative team. The next expedition phases in the year ahead are going to be full of more new and exciting discoveries.”
Expedition Science Team at the expedition start. Photo: Everest@ECORD_IODP3_NSF
Professor Brandon Dugan, Co-Chief Scientist of the expedition, adds: “We set out with ambitious goals to understand the origin and age of this offshore freshened groundwater system. It was challenging to operate in difficult drilling environments consisting of loose sand and mud. Thanks to great teamwork among the IODP3 technical staff, the science team, and the drilling crew, we managed to get great samples including through multiple groundwater pumping tests. Those tests were a critical to the Expedition and a first for scientific ocean drilling. And we did it! Now we have the samples for the science team to really dive into the data and understand the system, which will be helpful for understanding other offshore freshened groundwater systems around the world.”
Fellow Co-Chief Scientist Professor Rebecca Robinson continues: “The pump tests were challenging and required us to adapt our processes to get the best possible samples of the groundwater. In the end we pumped nearly 50,000 liters of water from nine distinct places, in terms of location and depth below seafloor – a huge success story for something so novel. For me in particular, as a geochemist not a hydrogeologist, I am so appreciative to everyone that leant their expertise. Especially the team of hydrogeologists from the British Geological Survey were outstanding.”
Professor Karen Johannesson, the third Co-Chief Scientist, explains: “Some of the groundwaters were remarkably dilute with salinities around and even below 1 psu (practical salinity unit). To put this into a context that most can understand, 1 psu is the same as 1 gram of total dissolved solids per liter. Seawater averages about 35 psu. Groundwaters with total dissolved solids less than 1 psu are fit for human consumption as a drinking water resource, whereas water with around 1 psu are fit for livestock. The presence of freshened groundwater in sandy, unconsolidated Paleogene and even Cretaceous continental shelf sediments 20 to 50 miles offshore is exciting. I look forward to discovering how these groundwaters are and what the past climate was like when these groundwaters entered these offshore aquifers.”
During the expedition, the science team rotated on and off the Liftboat Robert transported by helicopter or supply vessel. The entire science team will meet for the onshore operations at the Bremen Core Repository, at MARUM – Center for Marine Environmental Sciences at the University of Bremen (Germany) in January and February 2026 to split, sample, and analyze the sediment cores and water collected. The cores will be archived and made accessible for further scientific research for the scientific community after a one year-moratorium period. All expedition data will be open access in the IODP³ MSP data portal in the PANGAEA database, and resulting outcomes will be published.
International approach
41 science team members from 13 nations (Australia, China, France, Germany, India, Italy, Japan, Netherlands, Portugal, Sweden, Switzerland, United Kingdom, USA) take part in the expedition that consists of two phases: offshore and onshore operations. Offshore Operations has taken place between May and early August 2025. The expedition is conducted by the European Consortium for Ocean Research Drilling (ECORD) as part of the International Ocean Drilling Programme (IODP³), funded by IODP³ and the US National Science Foundation (NSF).More Information:
About the international research collaboration
About the European part of the program