CAOG - PhD Students

Miss Dawn White

The use of stable isotopes for the characterisation of Natural Organic Matter (NOM)

This PhD project aims to develop and test the utility of stable isotopic analysis for characterising and establishing the main precursors of dissolved organic carbon (DOC). Stable isotopic data of NOM will be obtained on both a whole sample and a compound specific basis to investigated the utility of stable isotope analysis for studying the source input, temporal and spatial dynamics (e.g., bioproductivity), transportation and fate of organic material in source water systems. A range of NOM samples will be studied since the chemical and physical nature of NOM is dependent on the source materials and surrounding environmental conditions, hence NOM from different locations can vary considerably in structure and behaviour. NOM fractions will be separately studied to establish the relationship between the structural moieties of NOM and specific organic precursors. A correlation of the source inputs of organics in the source waters with the subsequent occurrence of certain DBPs following treatment may also help identify which precursors are most significant with respect to DBP formation. For isotope analyses complex organics such as NOM often need to be separated into simplistic fractions prior to analysis. This can be achieved by chemical degradation (e.g. CuO) or off-line pyrolysis followed by column chromatography to produce less complex fractions on the basis of solubility in solvents of different polarity. New chemical and enzymatic degradation techniques, which selectively target specific structural bonds (e.g., C-N, C-O, C-S bonds), will be developed to produce relatively clean fractions suitable for compound specific isotope analysis (CSIA).

The utility of stable isotope analysis for following seasonal and geographical variations of organic species will be examined. The organic composition of source waters is likely influenced by a number of variables including the catchment environment, climate, seasons, etc. NOM will be periodically collected and isolated from selected source waters to cover seasonal and climatic variations.

Supervisors

Professor K. Grice

Co-Supervisors

Professor K. Grice, Dr Paul Greenwood

Associate Supervisors

Dr Rino Trolio (Water Corporatio), Professor Robert Kagi

Funding

CRC-WQT/ CIRIS