| Elucidating environmental processes at the molecular level is key to understanding a range of larger processes including carbon sequestration and cycling, contaminant transport and fate, and agricultural productivity. Unfortunately, environmental matrices, such as soil, are highly complex, heterogeneous, and often contain multiple phases (liquids, gels and solids) making their analysis by conventional methods challenging. Nuclear Magnetic Resonance (NMR) spectroscopy is arguably one of the most powerful and versatile tools in modern science, with the potential to provide unprecedented levels information as to structures and molecular interactions in complex environmental matrices. Despite this potential NMR is not as widely applied in the environmental research as other fields such as medicine and organic chemistry, in part due to the lack of experimental approaches specifically developed for environmental analysis. This thesis aims to develop a series of fundamental NMR experimental approaches that can improve the reliability, efficiency and information gained from environmental samples. Specifically, it introduces a novel and efficient optimization approach for the determination of fundamental NMR parameters. Following this it develops on a novel approach based on supercooled water to help assign chemical structures in complex mixtures was developed. The method presented enhances intramolecular spatial interactions and uses the resulting spatial correlations to edit mixtures and expands the range of molecules that can be assigned in situ without physical separation of mixtures. Subsequently, it discusses the optimization of high-resolution magic angle spinning (HR-MAS) for environmental samples and allows the transition from the study of static samples (solutions) to those containing more than one phase (liquids and gels). Ultimately while studying solutions and gels in situ is very important to study natural samples holistically in their native state. As such the ability to study all phases (liquids, gels and solids) at the same time is required. This necessitated the development of the comprehensive multiphase technology (CMP), which allows study of all bonds in all phases and is used to paint a molecular-level picture of an oil-contaminated soil along with the aforementioned improvements. The advances shown here in conjunction with CMP technology should prove invaluable in all future studies that require molecular-level information concerning any unaltered complex system. |
