Climate Change Literature Review 2019

New methods to understand climate change over previous millennia are providing researchers with a context and framework to tackle our current environmental challenges.

Analysis of airborne dust extracted from deep ice cores provides researchers with valuable data on our climate history. Antarctic ice cores provide the best information on global environmental conditions going back many thousands of years, but technical issues such as the small quantities and complexity of the study materials, and the need for close international co-operation, have proved challenging. However, recent collaboration between Diamond and Italian researchers has allowed development of new ‘clean room’ techniques to prepare and handle samples to minimise contamination before and during analysis. The researchers used a variety of techniques at Diamond including synchrotron radiation analysis using X-ray Fluorescence (XRF), X-ray Absorption Spectroscopy (XAS) and X-ray Powder Diffraction (XRD) on beamline B18. The team were also able to produce a set of consistent data which may provide a reference point for further significant developments in this important research field.

Professor Giovanni Baccolo and his team have also provided preliminary analytical data on deep ice core samples that may be up to 800,000 years old. The group showed that combining synchrotron radiation-based techniques, particularly XRF and X-ray absorption near edge structure spectroscopy (XANES), together with traditional grain size analysis show great promise for ice core science.

The biochemical composition of plankton shells provides another valuable indicator of past climate. A team from the University of Cambridge has worked with Diamond researchers to gain greater understanding of the processes controlling biogenic calcite deposition and trace element incorporation as well as post-mortem chemical alterations that could change the chemical composition of the shells. The researchers used phase contrast synchrotron tomography on beamline I13-2 to provide initial findings that will add to the existing body of data on prehistoric climate change.

Air pollution comes from many sources and Diamond provides a comprehensive range of expertise to support researchers in all aspects of atmospheric research. In particular, there is an urgent need to develop new, efficient systems to capture, store and manage carbon dioxide and sulphur dioxide emissions which contribute heavily to global environmental problems and health risks.

A China/UK study provided insights into the direct hydrogenation of carbon dioxide to methanol. These processes have the potential to reduce the greenhouse effect and allow storage of clean synthetic fuels. The researchers studied a stable copper-based catalyst on beamline B18 with Extended X-ray Absorption Fine Structure (EXAFS) which produces efficient carbon dioxide adsorption and enhances copper dispersion. Further studies on this potentially useful catalyst are ongoing.

Metal Organic Frameworks (MOF) are new materials with high surface area that are showing great potential for gas adsorption and storage. An international team from the UK, China, Russia and the USA collaborated to assess the efficiency of a novel MOF (MFM-305- CH3) using beamlines I11 and B22. The study included a range of techniques of in situ synchrotron X-ray and neutron powder diffraction, inelastic neutron scattering, synchrotron infrared and 2H (Hydrogen) NMR (nuclear magnetic resonance) spectroscopy and theoretical modelling to reveal the binding domains of carbon dioxide and sulphur dioxide in these materials. The study provides an important initial step into the design of new systems to limit atmospheric pollution.

Cerium oxide nanoparticles are used in some diesel fuel additives to improve fuel combustion efficiency and exhaust filter operation. However, these particles have been detected in air samples raising concerns about their potential human health impact. Previous studies have focused on particles larger than those emitted from vehicles and so a new study by the University of Birmingham, Northwestern University, Chicago and the Centre for Radiation, Chemical and Environmental Hazards at Harwell looked at particles of a more environmentally relevant size using a combination of methods. The study was funded by the UKs Natural Environment Research Council and supported by Public Health England.

Aerosol exposure and impact on lung tissue was assessed in an animal model exposed to cerium oxide aerosols using a combination of methods including synchrotron microfocus X-ray spectroscopy on beamline I18. Histopathology indicated mild lung inflammation with the correlated synchrotron analysis identifying the speciation of the cerium oxide particles. This initial study suggests that inhalation of these particles could produce long-term effects and further inhalation studies are urgently needed.
 

Production and use of bio-fuels is another approach in the fight against climate change and atmospheric pollution. For example, bio-diesel produced from vegetable oils or animal fats has numerous potential advantages over diesel fuel including energy security, improving air quality and providing safety benefits. However, there are numerous challenges to its use in modern internal combustion engines. One of these is that bio-diesel can crystallise and block fuel filters and fuel injection nozzles to cause engine failure. A UK study used Raman spectroscopy and X-ray powder diffraction on beamline I15, supplemented with neutron powder diffraction at ISIS Muon and Neutron Source to understand the crystallisation process of biodiesel in the attempt to design a more efficient product. These studies are ongoing.

Another UK study investigated the potential uses of glycerol which is the main by-product of bio-fuel production. One potential application is the production of hydrogen using proton exchange membrane fuel cell technology, whereas current industrial processes used to produce hydrogen result in high carbon dioxide emissions and add to the depletion of fossil fuel reserves. Glycerol can also be used to produce useful liquid products for the food, cosmetic and pharmaceutical industries. The researchers were able to show that a platinum-based nano-particle catalyst can be used to finetune the aqueous phase reforming of glycerol to form useful oxygenated liquid chemical or gas phase feedstocks. The study used the B18 Core EXAFS beamline with support and resources provided through the UK Catalysis Hub Consortium.

Managing the waste products of the nuclear industry remains one of the most challenging environmental issues that will have an impact over many thousands of years.

Uranium is typically the major component in spent nuclear fuels and many radioactive wastes. There is an urgent need to understand how uranium products corrode and how this affects its potential mobility into the environment during storage. An international team from the UK, USA and Germany characterised the products of metallic uranium corrosion formed under anaerobic, alkaline conditions, and investigated the reaction between the uranium corrosion products and silicate which is present in large quantities in all groundwater. The team used beamline B18 using X-ray absorption spectroscopy and other techniques to analyse particle sizes. The study showed that silicate can stabilize uranium dioxide as a colloid under environmentally relevant conditions with the extreme normal pH levels experienced in spent nuclear fuel storage. This work provides further understanding in this complex area which will lead to safer storage of radioactive materials.

A team from the University of Manchester assessed the value of iron nanoparticles (<100 nm) in treating groundwater contaminated with technetium which is a common problem at nuclear sites. Part of the study included use of XAS (X-ray absorption spectroscopy) on beamline B18. Addition of iron nanoparticles to samples from the Sellafield site in Cumbria stimulated the microbial community in sediment and proved to be an efficient method of removing technetium from groundwater. This could prove to be a highly effective means of environmental restoration in the future and these methods may be transferable into use against other environmental pollutants.

A collaborative project between a number of UK universities and the Japanese Atomic Energy Authority has provided valuable new information on the legacy of the Fukushima nuclear power plant disaster in 2011. Analysis of samples gathered close to the accident site have provided detailed understanding of the reactor damage and radioactive fallout behaviour following the accident and in subsequent years. The study included use of the I13-1 (coherence imaging) and the I18 (micro-focus imaging) beamlines using a range of complex techniques, including XANES, available at Diamond. These findings add to the international knowledge base as scientists design the next generation of nuclear power plants.

Mine waste is a common and damaging source of environmental pollution. A number of studies have been carried out at Diamond to understand the impacts of mine waste spills and to design effective treatments.

Failure of mining waste containment ponds can have significant impacts on the local environment. Vanadium is a valuable metal used in many industries but high concentrations of vanadium are extremely toxic to plant and animal life and it is classified in international guidelines as a priority environmental risk. A UK/Canadian team analysed samples from the Mount Polley mine tailings spill in Canada in 2014 in order to understand the cycling of vanadium in mine-affected environments and to aid land restoration and management schemes. Microfocus XANES spectra for magnetite, titanite and iron oxyhydroxide grains were collected on beamline I18. These findings allowed production of a detailed model of the origin and fate of vanadium that could be used in other river systems in the future.

Vanadium can also be released in high concentrations from residues of fossil fuel burning and steel making and is a considerable problem in leachate from storage sites with high pH, trace metals and solids damaging the environment. A joint research team from a number of UK universities also used Diamond beamline I18 to collect XAS spectra to study the impact and behaviour of steel slag leachate at the former steelworks at Consett, County Durham, UK. They found sufficiently high concentrations of vanadium to be of concern, but also natural processes that were able to minimise any harm, thus adding to the growing body knowledge of vanadium transport from mining leachate.

An Italian study has provided more information on the role of marine bivalves in environmental monitoring and the impact of mine waste pollution on the seabed. Samples taken from the Malfidano mining area in south west Sardinia were analysed on beamline I08 using scanning X-ray microscopy to assess the take up of zinc into bivalve shells. These techniques were useful in understanding bivalve biomineralization and highlight the ongoing importance of these species in environmental monitoring, and in particular the impact of marine pollution.

A number of different approaches to cleaning up water pollution have been explored at Diamond over the past year.

A Spanish research group has designed a new Metal Organic Framework (MOF) using small molecule single crystal diffraction on beamline I19. The new material could be used to remove a wide range of pollutants from water resources including inorganic heavy metals and organic dyes.

Another research study from a joint UK/Romanian research team examined the effectiveness of zinc adsorption using Fucus vesiculosis, a common seaweed species also known as bladder wrack or kelp. The team analysed the seaweed using synchrotron X-ray Fluorescence and X-ray Absorption Spectroscopy measurements of zinc on the I18 beamline, confirming that alginate is one of the main algae components responsible for metal binding. Further studies are looking at the potential for this seaweed to be used in the removal of zinc from contaminated waters and during waste water treatment.

A study from Leeds Univeristy highlights the potential of humic acids extracted from lignite and peat soil in cleaning up groundwater contaminated with chromium. The metal is widely used in industry and is the cause of much groundwater pollution across the world. It has two environmentally stable oxidation states; Chromium (Cr)VI which is toxic to plants and animals and Cr III which is an essential trace element for living organisms.

XAS spectra were collected from humic acid samples on beamlines I18 and B18 at Diamond. The study found that chromium is reduced from Cr VI to Cr III by reaction to humic acids over a wide range of pH values found in the environment, demonstrating that natural soil organic matter will reduce chromium. In addition, humic acids could be used as the basis of an engineered treatment scheme; further studies are required to design such systems.

Read more about the latest research from Diamond in our Science Highlights.