Microfluorination for Oxygen isotopes in Biogenic Silica (MOBiS)

Human-induced climate change has altered natural environments and human systems around the world, with widespread and increasingly severe impacts that are beyond natural climate variability. To develop a greater understanding of what drives environmental change and the influence it will have on ecosystems and Earth-processes (e.g. movement and storage of water and carbon), we can use natural archives (e.g. ocean and lake sediment records) that contain chemical variations of specific elements (isotopes) that relate to past climate change. The response of natural environments to climate change in the past can provide crucial information to investigate how the same environments might change in the future under different scenarios for global warming. For example, examining polar regions where melting ice caps contribute significantly to accelerating global sea level rise. Investigating polar ice melting in response to climate change in the geological past, including in periods that had a warmer climate than today, provides crucial information to identify the main controls on ice melting and determine the likelihood of future events in response to global warming. Information about past environmental change can also be used to assess the condition of an ecosystem before major human impact and the natural levels of variability that have occurred in past millennia, how the environment has changed due to human activity, how we can monitor and restore ecosystems today, and protect against future impacts from human activity.

The particular amount of specific chemical elements (isotopes) that natural materials are made of is determined by prevailing environmental conditions and this information is locked in to their structure as they grow. For example, the shells and skeletons of microscopic organisms living in the ocean record the ratio of oxygen isotopes in the water which they formed in. Over time (hundreds to millions of years), changes in climate lead to variations in the oxygen isotope composition of ocean waters and these are in turn preserved in the remains of creatures that have sunk and built up in ocean floor sediments. Layer-by-layer these remains accumulate preserving changes the signature of water chemistry in a time-ordered sequence; the deeper under the ocean floor the older the sediment. We can recover this sediment in sequence and investigate how isotopes in the skeletal remains change through the record, which allows for past changes in climate to be reconstructed. The more layers that can be analysed from a sediment sequence, the more detail we can obtain about past climate change.

The oxygen isotope composition of microscopic organisms that grow in any body of water and build skeletons made of glass (biogenic silica) is controlled by prevailing environmental conditions and is routinely used to reconstruct past climate. The extraction and measurement of oxygen isotopes from this material is a highly specialised technique, but requires large samples, dangerous chemicals, and is time and energy inefficient. Sediment archives are collected at great expense and difficultly, and produce limited sample material. Combined with the existing extraction method, this limits the amount of information available from oxygen isotopes in biogenic silica to answer important questions about past climate change.

To tackle this issue, we will purchase a new system that combines an automated, high-temperature sample reaction device and high precision isotope measurement instrument that do not require the use of dangerous chemicals, provide substantially higher sample throughput, and require significantly reduced sample sizes. The new system will enable a step-change from the existing method allowing BGS to process many more samples from each sediment sequence and also expand the range of environmental samples that can be analysed, e.g. from ocean, land and lake settings, that do not have high concentrations of biogenic silica.