The application and improvement of environmental methods of analysis

There exist numerous environmental problems demanding the attention of multi-disciplinary teams of scientists. By applying analytical methods, developing new methods or new technology, analytical chemists enable these teams to answer crucial questions leading to the solution of a problem. The research presented in this dissertation reports new knowledge gained and advancements made concerning the analyses of two classes of environmentally important compounds, namely herbicides and humic substances.; Gas chromatography-mass spectrometry (GC-MS) methods were adapted and applied to quantitatively analyze alachlor concentrations in field mesocosms. The results allowed for the determination of aquatic alachlor decay rates subjected to various controlled nutrient conditions. The decay rates showed strong correlation with the data trends for other monitored parameters, e.g. water chemistry and microbial conditions, which led to the conclusion that biotransformation was the dominant mechanism of alachlor degradation. A liquid chromatography-MS method for the analysis of two major alachlor metabolites, alachlor ethanesulfonic acid and alachlor oxanilic acid, was developed.; Several humic substances were characterized by quantitative 13 C and qualitative 31P nuclear magnetic resonance spectroscopy (NMR). Diffusion coefficient determinations of humic substances by pulsed-field gradient NMR were improved by implementing CONTIN software, which analyzes the data in a manner that considers the polydisperse nature of these complex mixtures. This method of data analysis was demonstrated and validated using standard humic substances. Subsequently, the CONTIN method was applied to investigate the aggregation behavior of humic acid pseudo-micelles and their interactions with small hydrophobic pollutants. Results from these aggregation studies indicated the presence of novel pseudo-phases for the humic acids. Therefore, an expansion of the membrane-micelle model of humus was proposed to include behavior similar to that displayed by associative polymers.