Wildfire is a spatially and temporally complex phenomenon that has served a vital role in ecosystem function for millennia. However, drinking water providers have become increasingly aware of wildfire’s impacts on the quality of surface water. Increased loads of organic and inorganic constituents, transported by stormflow, are common in streams within burned catchments. As changes in climatic conditions and increased development in wildfire prone areas continues, drinking water providers will need a better understanding of these changes in order to adapt.
Dissolved organic matter (DOM) has the propensity to react with chemical disinfectants to form toxic disinfection byproducts (DBPs). However, wildfire induced chemical changes to DOM can potentially encourage the formation of haloacetonitriles; unregulated DBPs with a lower threshold of toxicity. The goal of the first section in this thesis was to isolate wildfire heating temperature, to better understand how it changes the solubility and reactivity of DOM originating from mineral soil. This was achieved by collecting mineral soil samples from fire prone locations and artificially heating them in a muffle furnace. DOM solubility was heightened at moderate (250°C-350°C) heating temperatures. Additionally, dichloroacetonitrile (DCAN) and dichloroacetic acid (DCAA) formation were stimulated at moderate (250°C) and high (450°C) heating temperatures. To further explore this phenomenon, optical properties were employed to better understand the intrinsic qualities of DOM. Although we identified some surprising correlations between these optical properties and DBP yield, there is still much work to be done to understand the underlying mechanisms.
Heavy metal contamination can be highly detrimental to the utilitarian and aesthetic qualities of surface water. In several cases, heavy metals have been detected at problematic levels in surface waters as a result of wildfire. However, the concentration and species of these heavy metals is controlled by several complex, spatially heterogenous interactions. Therefore, there exists a need to perform more catchment level studies to contribute knowledge to this complicated issue, as well as inform local water utilities. In the second part of this thesis, the leachability of several heavy metals was assessed from mineral soil and ash samples collected from the Colorado Ryan Fire.</p
