Methyl halides: Concentrations, fluxes and stable carbon isotope ratios measured in the atmosphere, coastal waters, and soils

Methyl chloride and methyl bromide are trace atmospheric gases with both natural and anthropogenic sources. They are significant sources of chlorine and bromine to the stratosphere where they participate in catalytic ozone destruction. An understanding of their global budgets is important in order to predict future disruption to the ozone layer. The research presented in this dissertation focused on concentrations of methyl chloride and methyl bromide as well as the stable carbon isotope ratio of methyl chloride (delta 13C-CH3Cl) in the atmosphere and local waters. Latitudinal profiles of atmospheric concentrations over the Atlantic and Pacific Oceans resulted in expected distributions of methyl halide mixing ratios; higher concentration in the tropics for methyl chloride and higher concentration in the Northern Hemisphere for methyl bromide. The mean atmospheric delta 13C-CH3Cl measured was -39.8 +/- 1‰, with lower delta 13C-CH3Cl observed in the tropics. A global mass balance of delta13C-CH3Cl was analyzed.; During the course of this research, attention was also given to methods and instrumentation. A variation of soil flux measurement methodology involving a large-volume collapsible flux chamber was investigated and found to be suitable with minor alterations. During the course of this research, the instrument used for concentration measurements was automated and re-built. Flame sealed glass ampoules were investigated as a sampling and storage device for water samples and found to be inadequate, introducing as much as 70% uncertainty in one case.