Towards ultra-trace element measurements in organic-rich samples: tracing past and modern environmental changes

点击翻译按钮获取中文摘要

Earth's environment is everchanging. The causes and consequences of environmental changes are complex and represent a significant research frontier from which significant academic and societal impact can be derived if overcome. However, our capacity to study them are currently limited by our ability to measure a range of key biogeochemical tracers in environmental archives using state-of-art techniques. We aim to take a new step in analytical environmental geochemistry by setting up an ultra-trace element measurement facility specifically designed to interogate samples tracing past and present environmental change to understand i) how the Earth became habitable; ii) how anthropogenic activity affects climate, oceans, soils and groundwater and; iii) fingerprint sources of critical metals for a greener economy. Current limitations hinge around the challenging aspect of environmental archives which are typically rich in organic material difficult to digest, and the fact that key biogeochemical tracers are both in very low-abundance and affected by detrimental interferences in mass spectrometers. We will remedy these issues by setting up Microwave Digestion triple quadrupole ICP-MS facility (MD-Qubed) specifically designed to measure very low-abundance of technically challenging trace-elements in organic-rich samples. By allowing the quantification of the cycling of key biogeochemical tracers present in ultra-low level in environmental archives across the entire periodic table, this unique analytical facility will enable groundbreaking studies to tackle first order challenges pertaining to Earth's past, present and future environmental changes. Indeed, if some compounds like phosphate and nitrate are critical nutrients for life, others like uranium or arsenic are poisonous. Determination of the abundance of such geochemical tracers in organic-rich sediments precipitated from the oceans can act as fingerprints of past ocean chemistry. For instance, phosphate-levels in these samples can inform about nutrient limitation in past oceans and help decipher controls on the evolution of life. Other elements, like uranium, selenium and molybdenum, in the same sediments, or boron and lithium in marine carbonate archives (e.g., foraminifera, corals), may respectively tell about oxygen and carbon level of the oceans and atmosphere. Similarly, we aim to understand the distribution and mobility of anthropogenically-derived poisonous elements (e.g: uranium, arsenic, cadmium, cobalt...) in water, soils and sediments, and their impact on modern life-forms. Thus, studying elements in geological and modern samples is critical for tracing both past and modern environmental changes. A key aim of our facility will also be to develop methods to trace anthropogenic pollution related to mining and industrial activities but also sources of critical metals for a greener future. The improved detection limits of the MD-Qubed facility will allow tracing of key trace metals such selenium and tellurium in soils, elements that are necessary for a transition towards the green technology revolution. We will also take advantage of this technology to trace radionuclides (e.g., uranium, plutonium,...) in samples and marine organisms to examine potential toxicity and mobility through the Earth System. Such studies will work towards adapting viable mining approaches and the potential for pollution remedies for a greener sustainable future environment.Finally, setting up such a unique facility in Wales and the South West of the UK will benefit a large range of research groups interested in environmental changes, both regionally and nationally. It will also complement the newly set-up Cardiff Earth Laboratory for Trace Element and Isotope Chemistry (CELTIC) and doing so establish a new cutting-edge analytical facility in this region.