This dataset consists of silicon isotope data from deep-sea sediment cores taken off southeast Iceland. Samples of sea sponges were collected using piston cores and sediment cores aboard the RV Celtic Explorer in 2008 and dried or frozen for transportation. Organic matter was removed and samples were preserved for later analysis. Sample analysis occurred in 2012 as part of a comprehensive study of the carbon cycle. The data collected form the field component of the NERC-funded project "Unravelling the carbon cycle using silicon isotopes in the oceans". The project aimed to investigate deep sea sponges and the silicon they produce, in an effort to piece together the links between the supply of vital nutrients in different parts of the ocean and the crucial role other marine organisms play in absorbing CO2 from the atmosphere and storing it in deep sea sediments as organic carbon. The Discovery Science project was composed of New Investigators (FEC) Grant reference NE/J00474X/1 led by Dr. Katherine Rosemary Hendry of Cardiff University, School of Earth and Ocean Sciences. The project ran from 26 January 2012 to 30 September 2013. The silicon isotope data have been received by BODC as raw files, and will be processed and quality controlled using in-house BODC procedures and made available online in the near future. The raw files are available on request.

The cross-disciplinary themes will result in a diverse data catalogue. The ship collected data will be in the form of sea surface meteorology (2-D wind speed and direction, total irradiance, Photosynthetically Active Radiation/PAR, air temperature, atmospheric pressure, humidity); atmospheric carbon dioxide (pCO2); biological, chemical and physical properties and processes in the marine photic zone (carbonate chemistry - pCO2, total alkalinity, pH, DIC; dissolved gases - oxygen; nutrient concentrations, ammonium regeneration, nitrification, nitrogen fixation, zooplankon ecology, chlorophyll concentration, photosynthetic pigment composition, bacterial production, phytoplankton and bacterial speciation, concentrations of biogenic trace compounds such as dimethyl sulphide/DMS and dimthylsulphoniopropionate/DMSP, salinity, temperature, zooplankon ecology) and bioassays of these same parameters under different future IPCC CO2 and temperature scenarios. The long-term (18 month) laboratory based mesocosm experiments will include data on individual organism response (growth, immune response, reproductive fitness) under different future IPCC CO2 and temperature scenarios in rocky intertidal, soft sediment and calcareous biogenic habitats, as well as the effects on commercially important species of fish and shellfish. The analysis of sediment cores will provide greater resolution of the paleo record during the Paleocene-Eocene Thermal Maximum (PETM). Data will be used to aid the parameterisation of coastal and continental shelf seas (Northern Europe and the Arctic) model runs as well as larger scale global models. The shipboard fieldwork will take place around the UK, in the Arctic Ocean and the Southern Ocean. The mesocosms will look at temperate marine species common to UK shelf seas. Sediment cores have been collected from Tanzania. The models will look from the coastal seas of Northern Europe to the whole globe. Data to be generated will include data collected at sea, short-term (2-3 day) ship-board bioassays, from long-term (18 month) laboratory based mesocosm experiments and reconstructed paleo records from sediment cores. The 5 year UK Ocean Acidification Research Programme is the UK’s response to growing concerns over ocean acidification. Aims: 1 - to reduce uncertainties in predictions of carbonate chemistry changes and their effects on marine biogeochemistry, ecosystems and other components of the Earth System; 2 - to understand the responses to ocean acidification, and other climate change related stressors, by marine organisms, biodiversity and ecosystems and to improve understanding of their resistance or susceptibility to acidification; 3 - to provide data and effective advice to policy makers and managers of marine bioresources on the potential size and timescale of risks, to allow for development of appropriate mitigation and adaptation strategies. The study unites over 100 marine scientists from 27 institutions across the UK. It is jointly funded by Department for Environment, Food and Rural Affairs (Defra), the Natural Environment Research Council (NERC) and Department of Energy and Climate Change (DECC).