Soils in natural temperate ecosystems store substantial amounts of carbon in the form of soil organic matter. This represents a vital service by these ecosystems (including forest, grasslands as well as wetlands), as these organic matter reservoirs have been built up from decaying vegetation that previously fixed carbon in its biomass from atmospheric CO2. There is significant uncertainty regarding the persistence of this reservoir of carbon in soils, both from climatic influences and changes in land use. The influence of temperature on the formation of plant biomass as well as decay processes are well researched, but have so far been largely considered separately. More recently, it has emerged that fundamental differences in the way in which vegetation interacts with microbial organisms in the soil have significant impact on the storage of carbon in soil organic matter. The symbiotic relationship of plants with particular forms of fungi (mycorrhizas) is of particular interest. The role of these fungi in the supply of nutrients to plants is well established, but recent findings highlight important influences of these organisms also on the formation and decomposition of organic matter. Changes in vegetation form can drastically influence the type of fungal (i.e. mycorrhizal) diversity in the soil, with direct implications for organic matter formation and decay. However, the interaction between vegetation form, fungal association and soil organic matter storage has not been investigated systematically. This research addresses the way in which changes in vegetation that also alter the type of mycorrhizal fungal association results in changes in organic matter storage. Specifically, we will investigate a switch from grasslands to coniferous forests. This kind of vegetation change is relatively common in temperate regions due to an encroachment of trees near treelines, following a warming climate, and managed land use changes where upland pasture may be planted with commercial forestry or for 'rewilding' efforts. Our methodology combines experimental decomposition studies with ecosystem model development to enable a new generation of predictive models (based on existing modelling tools) able to incorporate plant-microbial interactions. Land managers and policy makers alike require a full understanding of the consequences of this kind of vegetation change on soil carbon storage, as apparent benefits in carbon uptake by vegetation may be annulled by corresponding losses in storage within the soil.

Erosion processes mobilize and deliver organic carbon (OC) from soils and plants and can supply it to rivers. The resultant discharge of carbon by rivers to the world's oceans is globally significant, with current estimates of 160 Mega tonnes of carbon per year in particulate OC (POC, larger than 0.2 microns) and 200 Mega tonnes of carbon per year in dissolved OC (DOC, smaller than 0.2 microns). These estimates, however, do not account for material larger than about half a centimeter, including pieces of large wood. Few studies have investigated the large-scale patterns of wood delivery, decay, and transport in rivers, and so we have limited knowledge of how large wood influences OC discharge to the ocean. This knowledge gap leads to our primary research goals, which are to (i) quantify annual carbon discharge in the form of large wood versus other sources of DOC and POC from the Mackenzie River drainage of Canada to the Arctic Ocean and (ii) estimate storage volume, residence time, and decay rates of large wood in the drainage basin. Our focus on the Mackenzie River is based on the fact it is the largest source of river sediment and POC to the Arctic Ocean, and anecdotally has large volumes of wood moving through its delta to the ocean, but these fluxes have not been measured. The transformative aspects of the proposed research are: (1) quantification of proportions of OC exported as wood versus finer material from a large river, providing insight into the relative importance of different sources of OC under modern day conditions, and (2) the first assessment of the relative ages of material across the full range of particulate sizes carried by a large river from < 500 microns to large wood, providing a clearer basis for predicting how changes in the fate of coarser OC and large wood may impact the carbon cycle under a warming climate. This project will also substantially advance understanding of wood dynamics in large river basins under a warming climate that will alter wood recruitment, transport, and deposition processes, altering timing, volume, and placement of wood exports to the Mackenzie Delta and the Arctic.

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

Every year, fires burn more than 500 million ha of the land surface on Earth. These fires leave residues of partially burned biomass which are deposited on the soil surface as "pyrogenic carbon" (PyC). It is estimated that as much as 114 to 379 Tg of PyC are added to soils each year, and global models predict that fire frequency and intensity will increase in many areas. Much of this PyC is deposited on to the soil surface and subsequently incorporated into deeper layers, so that it can account for as much as 50% of total carbon stored in soils in some fire prone ecosystems such as tropical savannahs. Storage of pyrogenic carbon in soils matters a lot to the way in which natural and managed ecosystems interact with the global climate system. PyC has an inherently slow turnover once it is in the soil, meaning that it will persist much longer than organic matter deposited on or in soils that have not been exposed to fire. Remarkably, however, we largely ignore the fate and overall contribution of PyC to global carbon cycling. This is due to the fact that the scientific community so far only has a rudimentary understanding of what determines PyC distribution and turnover in soils. There have been significant advances in understanding the role of charred biomass added to soil as an agricultural practice, and we have a reasonable understanding of these systems and how it interacts with soil organisms and physical factors. However, we require a much better understanding of processes underlying the changes of PyC particles, and stabilisation of carbon introduced to the soil after fire, in order to model current PyC dynamics, and be able to forecast these under future climates. Particularly biological processes, such as the role of invertebrate soil animals and different groups of soil microbial organisms have so far not received sufficient attention. We propose a programme of research directed at creating a novel soil-PyC model that can be linked to regional and global carbon-climate models, which so far ignore PyC. We will achieve this through a number of experiments based in a tropical savannah system in Gabon. This provides an ideal experimental set-up, as these fire prone systems have a significant abundance of PyC in the soil profile, and we will be able to link to a long-term fire manipulation field experiments in the Lopé National Park. Using targeted soil coring for contrasting fire return intervals, combined with the determination of the age of PyC (usingnatural 14C abundance) across the profile, we will be able to derive residence times of this stable soil carbon reservoir. By using isotopically labelled PyC (based on plants grown under enrichment with 13C, a non-harmful, stable isotope of carbon), we aim to gain a better mechanistic and quantitative understanding of soil PyC dynamics. This approach is linked to manipulations of soil animal presence, as these are hypothesised to have a significant influence over the distribution and turnover of PyC in the soil. Insights from the isotopic tracer study will be used to develop a novel soilorganic matter model to incorporate PyC dynamics for the first time, We will be able to parameterise this new model with our experimental data and validate simulated turnover against our independently assessed turnover time of PyC pools.

"The importance of the physical sciences to advance life sciences has never been greater", and inventive chemistry is continuously needed to program, understand and control function. This proposal fits within this context with innovation in the field of radiochemistry to advance molecular imaging. Positron-emission tomography (PET) is a functional and quantitative molecular imaging technology to interrogate biological processes in vivo, facilitate drug discovery and experimental medicine, enable early-stage clinical trials, and guide clinical practice (e.g. cancer and neurological disorders diagnosis, staging, and response to treatment). Combined with other diagnostic tests, this technology can facilitate for example the diagnosis of cancer, evaluate epilepsy, Alzheimer's disease and coronary artery disease. PET scans are routinely performed in the clinic and to support pharmaceutical drug discovery programs. A radiopharmaceutical (radioactive tracer) is required to perform these scans because the technique relies on the emission of gamma rays. These radioactive molecules must be prepared in specialist laboratories that performs radiochemistry with a cyclotron-produced positron emitting radioisotope such as commonly used 18F. Since the half-life of 18F is short (just under 110 minutes), the chemistry involved is challenging. Many groups including our laboratory have focused on novel radiochemical transformations for 18F-labelling because fluorine substitution is frequently encountered in pharmaceutical drugs. Labelling strategies that make use of ubiquitous precursors are the most sought-after, especially if these precursors are amenable to divergent radiochemistries. This is exactly what we will achieve with this project. We propose to develop novel 18F-radiochemistries using ubiquitous primary amines to accelerate PET ligand and radiopharmaceutical discovery. Our strategy consists of converting amines into pyridinium salts that are highly versatile synthetic intermediates acting either as electrophiles or as redox-active precursors. This rich reactivity profile offers the possibility to access a large diversity of 18F-labelled molecules through either direct 18F-fluorination or 18F-fluoroalkylation/arylation from primary amines. Such radiochemistry will streamline access to molecules that are either difficult to label or not possible to label with current technologies. All labelling reactions will be performed on an automated platform that is widely used in the UK and in the world. This aspect of the project is very important to ensure rapid translation of the novel radiochemistry proposed from a research laboratory to the clinic for immediate impact and use to improve patient healthcare, and ultimately for the manufacturing of new PET diagnostics or radioligands.